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_3 value "Sequencing identified 4 differentially expressed genes enhanced by tracheal ligation: hepatoma-derived growth factor (HDGF), ribosomal protein S24, stathmin, and parathyroid hormone (PTH)." provenance.
_3 value "Sequencing identified 4 differentially expressed genes enhanced by tracheal ligation: hepatoma-derived growth factor (HDGF), ribosomal protein S24, stathmin, and parathyroid hormone (PTH)." provenance.
_3 value "CD163 expression is also suppressed by proinflammatory mediators like lipopolysaccharide (LPS), interferon-gamma (IFN-gamma), and tumor necrosis factor alpha, whereas IL-6 and the antiinflammatory cytokine interleukin-10 (IL-10) strongly up-regulate CD163 mRNA in monocytes and macrophages." provenance.
_5 value "B9 clones expressing either wild-type FGFR3 at high levels or mutant FGFR3 displayed increased phosphorylation of STAT3 and higher levels of bcl-x(L) expression than did parental B9 cells after cytokine withdrawal." provenance.
_6 value "B9 clones expressing either wild-type FGFR3 at high levels or mutant FGFR3 displayed increased phosphorylation of STAT3 and higher levels of bcl-x(L) expression than did parental B9 cells after cytokine withdrawal." provenance.
_3 value "Retrovirally expressed Hox B3 promotes tumor-induced angiogenesis in vivo." provenance.
_5 value "Observations in obese men suggest enhanced inactivation of cortisol by 5alpha-reductase and altered reactivation of cortisone to cortisol by 11betahydroxysteroid dehydrogenase type 1 (11betaHSD1" provenance.
_4 value "We conclude that greater inactivation of glucocorticoids by 5alpha-reductase in liver and 11betaHSD2 in kidney combined with impaired reactivation of glucocorticoids by 11betaHSD1 in liver may increase the MCR of glucocorticoids and decrease local glucocorticoid concentrations at these sites." provenance.
_6 value "enhanced 11betaHSD1 in omental adipose tissue may increase local glucocorticoid receptor activation and promote obesity." provenance.
_3 value "PGDH promoter was strongly induced by phorbol ester" provenance.
_3 value "TR and the other two [13-cis-retinoic acid/isotretinoin and all trans-retinoic acid] retinoids dose-dependently induced tenascin-C expression in the fibroblasts." provenance.
_5 value "The glial cell line-derived neurotrophic factor (GDNF) family ligands (GFLs) (GDNF, neurturin, artemin, and persephin) are critical regulators of neurodevelopment and support the survival of midbrain dopaminergic and spinal motor neurons in vitro and in animal disease models making them attractive therapeutic candidates for treatment of neurodegenerative diseases. The GFLs signal through a multicomponent receptor complex comprised of a high affinity binding component (GDNF-family receptor alpha-component (GFRalpha1-GFRalpha4)) and the receptor tyrosine kinase RET." provenance.
_5 value "Furthermore, IL-18R at least partly shares the signal transducing system with IL-1R. Thus, the IL-18-IL-18R system has a striking similarity to the IL-1-IL-1R system. From entrez gene summary of IL1R1: The protein encoded by this gene is a cytokine receptor that belongs to the interleukin 1 receptor family. This protein is a receptor for interleukin alpha (IL1A), interleukin beta (IL1B), and interleukin 1 receptor, type I(IL1R1/IL1RA). It is an important mediator involved in many cytokine induced immune and inflammatory responses." provenance.
_7 value "We report in this study that CDK9, the cyclin T associated kinase, which phosphorylates and activates RNA-Polymerase II, suppresses B-Myb autoregulation through direct interaction with the carboxyl-terminus of the B-Myb protein." provenance.
_4 value "At the time of disease onset (day 7), a 2 to 5-fold increase in expression of CCR2 was observed. In GL3-treated mice, reduced levels of CCR2 was observed on day 6 and remained lower than in the EAE controls on day 7." provenance.
_5 value "A STAT3 peptide was efficiently phosphorylated on Ser727 in a CNTF-dependent manner by mTOR, but not by a kinase-inactive mTOR mutant or by p70 S6 kinase." provenance.
_5 value "P311 mRNA expression was decreased sharply in both neural and smooth muscle cells when the cells were transformed by coexpression of the oncogenic tyrosine kinase receptor Met and its ligand hepatocyte growth factor/scatter factor." provenance.
_6 value "In transient transfection assays, AES repressed p65-driven gene expression. AES also inhibited NF-kappaB-dependent gene expression" provenance.
_5 value "Furthermore, Erk-2 phosphorylated threonine 1179 and serine 1185 (and to a lesser extent, serine 395) in vitro, suggesting the importance of this pathway for SRC-1 regulation." provenance.
_5 value "PhosphoElm data from PMID 15212693" provenance.
_4 value "NGF induces PTEN expression of PC12 cells" provenance.
_3 value "Resveratrol inhibited PMA-mediated activation of protein kinase C and the induction of COX-2 promoter activity by c-Jun." provenance.
_2 value "In atherogenesis, elevated plasma levels of low density lipoprotein (LDL) lead to the chronic presence of LDL in the arterial wall. There, LDL is modified (eg, oxidized), and these modified lipoproteins activate endothelial cells, which attract circulating monocytes. These monocytes enter the vessel wall, differentiate into macrophages, and subject the modified lipoproteins to endocytosis through scavenger receptor pathways. This unrestricted uptake, which is not limited by intracellular cholesterol levels, eventually leads to the formation of lipid-filled foam cells, the initial step in atherosclerosis" provenance.
_4 value "jubilant" provenance.
_4 value "IGF-I (10 nM) stimulation of MCF-7 breast cancer cells caused a transient tyrosine phosphorylation of IRS-1 that was maximal at 15 min and decreased thereafter." provenance.
_6 value "Furthermore, expression of the activated Rac1(V12) in NIH 3T3 cells leads to an increased A6/twinfilin localization to nucleus and cell cortex, whereas a dominant negative form of Rac1(V12,N17) induces A6/twinfilin localization to cytoplasm." provenance.
_5 value "calcineurin up-regulates slow muscle fiber genes in cultured C2C12 muscle cells Transcriptional activation of the myoglobin and slow troponin I (TnI) genes by calcineurin was dependent on adjacent binding sites for NFAT and MEF2." provenance.
_6 value "Treatment of human umbilical vein endothelial cells (HUVEC) with vascular endothelial growth factor (VEGF, 25 ng/ml) promoted tyrosine phosphorylation and activation of KDR which associates with PLC-gamma and phosphorylates at tyrosine residue. This effect was inhibited by SU5416, a specific KDR antagonist. It was also shown that either (N or C-terminal) SH2 may mediate interaction with tyrosine 951 in KDR; tyrosine 1175 also fosters KDR/PLC-gamma interaction. Treatment with PlGF (Flt1 agonist) had no effect, suggesting that VEGF induces activation of PLC-gamma is mediated via KDR receptor." provenance.
_5 value "# Ariadne: Other orphan receptors including RORalpha2, RORgamma and COUP-TFI are also potentiated by CaMKIV. [Regulation]" provenance.
_4 value "The 52kDa isoform of Shc was phosphorylated in response to insulin or EGF stimulation." provenance.
_3 value "we have previously mapped taxol induced phosphorylation sites to be Ser-70 and 87 residues of Bcl2 protein" provenance.
_3 value "Moreover, the expression of Drg-1 is controlled by several known cell differentiation reagents, such as ligands of peroxisome proliferator-activated receptor gamma (troglitazone and BRL46593) and of retinoid X receptor (LG268), and histone deacetylase inhibitors (trichostatin A, suberoylanilide hydroxamic acid, and tributyrin)." provenance.
_5 value "High concentrations of stauro of up to 1 microM only partially inhibit IL-3-stimulated Bcl2 phosphorylation but completely block PKC-mediated Bcl2 phosphorylation in vitro" provenance.
_3 value "COX-2 is inducible by oncogenes ras and scr, interleukin-1, hypoxia, benzo[a]pyrene, ultraviolet light, epidermal growth factor, transforming growth factor beta, and tumor necrosis factor alpha." provenance.
_3 value "COX-2 synthesizes prostaglandin E2 (PGE2) which stimulates bcl-2 and inhibits apoptosis, and induces interleukin-6 (IL-6) which enhances haptoglobin synthesis. PGE2 is associated with tumor metastases, IL-6 with cancer cell invasion, and haptoglobin with implantation and angiogenesis" provenance.
_3 value "COX-2 synthesizes prostaglandin E2 (PGE2) which stimulates bcl-2 and inhibits apoptosis, and induces interleukin-6 (IL-6) which enhances haptoglobin synthesis. PGE2 is associated with tumor metastases, IL-6 with cancer cell invasion, and haptoglobin with implantation and angiogenesis" provenance.
_3 value "COX-2 synthesizes prostaglandin E2 (PGE2) which stimulates bcl-2 and inhibits apoptosis, and induces interleukin-6 (IL-6) which enhances haptoglobin synthesis. PGE2 is associated with tumor metastases, IL-6 with cancer cell invasion, and haptoglobin with implantation and angiogenesis" provenance.
_4 value "Ligation of alpha 5 beta 1 using activating mAb JBS5 (which acts as agonist similar to FN N-terminal fragment) up-regulates the inflammatory mediators such as NO and PGE2 as well as the cytokines, IL-6 and IL-8. Furthermore, up-regulation of these proinflammatory mediators by alpha 5 beta1 integrin ligation is mediated via induction and autocrine production of IL-1 beta, because type II soluble IL-1 decoy receptor inhibits their production." provenance.
_7 value "Ligation of alpha 5 beta 1 using activating mAb JBS5 (which acts as agonist similar to FN N-terminal fragment) up-regulates the inflammatory mediators such as NO and PGE2 as well as the cytokines, IL-6 and IL-8. Furthermore, up-regulation of these proinflammatory mediators by alpha 5 beta1 integrin ligation is mediated via induction and autocrine production of IL-1 beta, because type II soluble IL-1 decoy receptor inhibits their production." provenance.
_4 value "IL-18 increased IgE production. A significant 5-fold increase was observed as compared with the 54.4 6 ng/ml total serum IgE concentration of the PBS-treated naive mice." provenance.
_4 value "Treatment with IL-18 increased the production of IFNG, IL-4 and IL-5." provenance.
_4 value "The CIN85-c-Cbl association was enhanced shortly after stimulation of 293 cells with epidermal growth factor (EGF) and gradually diminished to a basal level, which correlated with a tyrosine phosphorylation level of c-Cbl." provenance.
_4 value "Pubmed:gene: Mouse peroxiredoxin V is a thioredoxin peroxidase that inhibits p53-induced apoptosis." provenance.
_7 value "We conclude that PKC mediates the FGF-2-induced effects on cardiac GJs and that PKCepsilon likely interacts with and phosphorylates cardiac Cx43 at sites of intercellular contact." provenance.
_4 value "The suppressive effect of IL-18 on PGE(2) production was mediated by interferon (IFN)-gamma because anti-human IFN-gamma-antibody prevented IL-18-induced reduction in PGE(2)." provenance.
_5 value "In MKN45, KATOIII and LS174T, cotransfection with TFF reporter genes and GATA-6 expression vectors revealed that GATA-6 activates TFF1 and TFF2 4-6-fold, without an effect on TFF3." provenance.
_4 value "PC-12 cells treated with 100 ng/ml of NGF for 5 minutes showed increased tyrosine phosphorylation of Shc1." provenance.
_4 value "PC-12 cells treated with 100 ng/ml of NGF for 5 minutes showed increased tyrosine phosphorylation of Shc1." provenance.
_6 value "Furthermore, Etk activated STAT3-mediated gene expression in synergy with this Src mutant." provenance.
_3 value "In cultured cells, HIG1 and HIG2 expression is induced by hypoxia and by glucose deprivation, but their expression is not induced by serum deprivation, UV, or ionizing radiation." provenance.
_4 value "It was found that 5-LO in the Epstein-Barr virus-transformed B-lymphocytic cell line BL41-E95-A is activated by addition of hydrogen peroxide or xanthine/xanthine oxidase and after increasing the oxidative state of the cell" provenance.
_6 value "after the epidermal growth factor stimulation, Chat and Cas were colocalized with actin filaments at ruffling membranes Chat transduces signals of tyrosine kinases and MAP kinases to Cas signaling pathway" provenance.
_5 value "in Chat-overexpressed cells, the activity of c-Jun N-terminal kinase was up-regulated" provenance.
_5 value "treatment of cells with epidermal growth factor or nerve growth factor increased the phosphorylation level of Chat, phosphorylation of Chat by MAP kinase" provenance.
_4 value "Phorbol-12-myristate-13-acetate, a PKC activator, robustly increased RGS2. This signal was attenuated by the PKC inhibitor GF 109203X (50 +/- 4%) and by phorbol-12, 13-dibutyrate-mediated down-regulation of PKC" provenance.
_4 value "Phorbol-12-myristate-13-acetate, a PKC activator, robustly increased RGS2. This signal was attenuated by the PKC inhibitor GF 109203X (50 +/- 4%) and by phorbol-12, 13-dibutyrate-mediated down-regulation of PKC" provenance.
_6 value "Simultaneous treatment with OA plus dibutyryl cAMP caused a synergistic up-regulation of steady-state levels of HO-1 mRNA, and the specific protein kinase A inhibitor KT5720 markedly reduced the OA-dependent HO-1 mRNA induction." provenance.
_5 value "Simultaneous treatment with OA plus dibutyryl cAMP caused a synergistic up-regulation of steady-state levels of HO-1 mRNA, and the specific protein kinase A inhibitor KT5720 markedly reduced the OA-dependent HO-1 mRNA induction." provenance.
_5 value "Modified assertion" provenance.
_3 value "The icv NPY-induced food intake was remarkably reduced in Y1-/- mice The Y1 receptor therefore plays a dominant role in NPY-induced feeding" provenance.
_5 value "The icv NPY-induced food intake was remarkably reduced in Y1-/- mice The Y1 receptor therefore plays a dominant role in NPY-induced feeding" provenance.
_7 value "oestrogenic conditions SRC-1 preferentially binds to the ER which effectively sequesters it thereby reducing enhancer activity" provenance.
_6 value "PDK1 has now been shown to play a central role in activating many of the AGC subfamily members (reviewed in [150,151]). Apart from phosphorylating PKB on Thr308, PDK1 phosphorylates the equivalent residues on PKC isoforms [48,152,153], p70-S6K [32,154], the three isoforms of SGK [27,28,155] and PKA [156] (Figure 6)." provenance.
_4 value "# Ariadne: Furthermore, Ang II stimulated the expression of immediate-early genes, including c- fos , c- jun , jun B , Egr-1 , and c- myc (Sadoshima and Izumo, 1993 )" provenance.
_4 value "# Ariadne: Furthermore, Ang II stimulated the expression of immediate-early genes, including c- fos , c- jun , jun B , Egr-1 , and c- myc (Sadoshima and Izumo, 1993 )" provenance.
_4 value "# Ariadne: Furthermore, Ang II stimulated the expression of immediate-early genes, including c- fos , c- jun , jun B , Egr-1 , and c- myc (Sadoshima and Izumo, 1993 )" provenance.
_6 value "Once activated, Raf-1 phosphorylates serines in the catalytic sites of MKK/MEK [345,367]. MKK1/MEK1 and MKK2/MEK2 activate members of the MAP kinase family (ERK-1/ERK-2)," provenance.
_6 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_4 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_6 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_3 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_3 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_3 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_3 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_3 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_3 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_3 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_3 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_3 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_4 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_4 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_3 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_3 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_3 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_3 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_3 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_4 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_5 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_3 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_3 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_5 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_3 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_3 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_3 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_3 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_3 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_3 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_3 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_6 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.
_3 value "Simultaneous overexpression of selenophosphate synthetase and phospholipid-hydroperoxide GSH peroxidase (PHGPx) [250] blocks activation of NF-kB by IL-1. Overexpression of SOD [84] or GSH peroxidase [81, 211] abolished NF-kB activation by preventing degradation of IkB after stimulation with TNF-a. The precise mechanism(s) through which oxidants and reductants influence activation of NF-kB is presently unknown; however, there is evidence that antioxidant enzyme (AOE372), a redox-sensitive thioredoxin peroxidase, regulates IkB phosphorylation [246]. Phosphatases The phosphatases are an important component of most signal transduction pathways, because failure to reverse kinase actions can disrupt normal cellular functions. For example, transfection of human fibroblasts with constitutively active ras (hRasV12) inhibits cell growth and ultimately results in a senescentlike phenotype [441]. Similarly, constitutive ERK activation has an inhibitory effect on cell cycle progression [442,443]. Both the serine/threonine phosphatases and the PTPs are known to be redox-sensitive [82,144,153,156,271,281, 444-449]. The mechanism of redox effects on activity is probably best understood for the PTPs. Without exception, the PTPs contain a highly conserved region of 11 amino acid residues in their catalytic domain; specifi- cally, (Ile/Val)-His-Cys-X-Ala-Gly-X-X-Arg-(Ser/Thr)- Gly, where X is a nonconserved amino acid [17]. Either oxidation or mutation of the cysteine renders these molecules inactive [17,281]. H2O2 is a potent inhibitor of PTPs. As in the case of other oxidants, H2O2 probably oxidizes the thiolate anion at the catalytic site [280]. Because formation of a phosphorylcysteine intermediate seems to be critical to PTP activity [450-452], blocking it through oxidation of the cysteine inactivates the molecules. In many cases, treatment of cells with H2O2 stimulates increases in protein phosphorylation by inhibiting phosphatase-catalyzed removal of phosphate groups. Furthermore, mitogens that increase cellular ox- idant production may stimulate phosphorylation indirectly by decreasing phosphatase activity. Additional mechanisms are involved in stimulation of pathways activated by growth factors that increase oxidant production, however, because there are known instances in which the oxidants they produce have no effect on protein phosphorylation. For example, TGF-b1 stimulates phosphorylation of numerous proteins and has been shown to cause a large increase in H2O2 production; however, its effects on protein phosphorylation are not blocked by catalase [453]. Furthermore, H2O2 is effective in promoting phosphorylation of phospholipase D, the PDGF receptor, and PKC-a even after pretreatment of Swiss 3T3 fibroblasts with orthovanadate to inhibit phosphatases [454]. Thus, although diminished phosphatase activity may partially account for increased phosphorylation in some cases, it cannot totally account for oxidation effects on phosphorylation in every case. SPECIFICITY In general, there is good agreement between studies on redox effects on any given gene; albeit, not all oxidizing or reducing treatments exert equivalent effects. This is clearly demonstrated in studies of pag , which encodes a protein associated with cellular proliferation. Pag protein inhibits the tyrosine kinase activity of the Abelson (abl ) protein by binding to its SH3-binding domain [455]. BSO, menadione, sodium arsenate, and diethyl maleate all stimulate pag expression, but H2O2 does not [269]. Conversely, H2O2 stimulates c-fos expression (Table 1), although 4-hydroynonenal (a product of v-6-polyunsaturated fatty acid peroxidation) not only fails to induce c-fos expression but is actually inhibitory to c-fos induction by EGF and PDGF [185]. Similarly, some oxidants such as diamide decrease hypoxia-induced signals [201], although others such as H2O2 increase them [124]. As might be expected, the effects of any stimu..." provenance.

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