Response to oxidative stress

The importance of having adequate supplies of NADPH for the regeneration of these various enzymes cannot be over emphasized. In normal situations this cofactor can be adequately provided by the reductive pentose phosphate pathway. Monitoring the activity of the pentose phosphate pathway has been proposed as a unique way to study the metabolic response to oxidative stress, since the glutathione peroxidase activity is coupled via glutathione reductase to the enzyme glucose-6-phosphate dehydrogenase (Ben Yoseph et ah, 1994). 

IO.4 Importance of Cell Type in Response to Oxidative Stress... 

In biochemical systems, acid-base and redox reactions are essential. Electron transfer plays an obvious, crucial role in photosynthesis, and redox reactions are central to the response to oxidative stress, and to the innate immune system and inflammatory response. Acid-base and proton transfer reactions are a part of most enzyme mechanisms, and are also closely linked to protein folding and stability. Proton and electron transfer are often coupled, as in almost all the steps of the mitochondrial respiratory chain. 

Shenton, D., Smirnova, J. B., Selley, J. N., Carroll, K., Hubbard, S. J., Pavitt, G. D., Ashe, M. P., and Grant, C. M. (2006). Global translational responses to oxidative stress impact upon multiple levels of protein synthesis. J. Biol. Chem. 281, 29011—29021. 

Numerous excellent reviews on the possible role of oxygen radicals in cancer and carcinogenesis have been published 10-20 years ago [147-153], Earliest studies have been much concerned with the role of SOD in tumor cells. Despite some contradictory results, it is general conclusion that tumor cells are usually characterized by lowered CuZnSOD activity and always by lowered MnSOD activity [147]. The origin of SOD declining in cancer cells is unknown. It has been suggested that MnSOD is not induced in cancer immortalized cells in response to oxidative stress, but the reason of this is uncertain [154],... 

Bulteau, A. L., Szweda, L. I., and Friguet, B. (2006). Mitochondrial protein oxidation and degradation in response to oxidative stress and aging. Exp. Gerontol. 41, 653-657. 

Mitochondria are also involved in the cell s response to oxidative stress. As we have seen, several steps in the path of oxygen reduction in mitochondria have the potential to produce highly reactive free radicals that can damage cells. The passage of electrons from QH2 to cytochrome bL through Complex III, and passage of electrons from Complex I to QH2, involve the radical Q as an intermediate. The Q can, with a low probability, pass an electron to 02 in the reaction... 

Zhang J, Ohta T, Maruyama A, Hosoya T, Nishikawa K, Maher JM, Shibahara S, Itoh K, Yamamoto M. 2006. BRG1 interacts with Nrf2 to selectively mediate HO-1 induction in response to oxidative stress. Mol Cell Biol 26 7942-7952. 

Numazawa S., Ishikawa M., Yoshida A., Tanaka S., and Yoshida T. (2003). Atypical protein kinase C mediates activation of NF-E2-related factor 2 in response to oxidative stress. Am. J. Physiol. Cell Physiol. 285 C334-C342. 

These results highly suggested that S100A2 oxidation and translocation is associated with early cellular responses to oxidative stress. 

Houle F, Rousseau S, Morrice N, Luc M, Mongrain S, Turner CE, Tanaka S, Moreau P, Huot J. Extracellular signal-regulated kinase mediates phosphorylation of tropomyosin-1 to promote cytoskeleton remodeling in response to oxidative stress Impact on membrane blebbing. Mol Biol Cell 2003 14 1418-1432. 

Yeh, G.C. et al. (1987) Adriamycin resistance in human tumor cells associated with marked alterations in the regulation of the hexose monophosphate shunt and its response to oxidant stress, Cancer Res. 47, 5994-5999. 

Ml. Ma, Y. S., Studies of the response to oxidative stress of the cybrids harboring the A8344G mitochondrial DNA mutation. Master s thesis. Institute of Biochemistry, National Yang-Ming University, Taipei, Taiwan, 1997. 

Increase in TAC is not always a good prognostic it may simply indicate an initial response to oxidative stress, as with concentrations of individual antioxidants and activities of antioxidant enzymes, or when it is due to disturbances in uric acid metabolism. Because uric acid is the main determinant of TAC of blood plasma, TAC increases in situations when the concentration of urate is increased, for example, in metabolic disorders and kidney failure. TAC is increased in urine from renal transplant recipients with delayed graft function (SI6). Ischemia of small intestine leads to an increase in TAC of rat blood serum, which is maximal (almost twofold) immediately after termination of 45-min ischemia (S22). TAC of blood plasma of rats poisoned with a high dose of carbon tetrachloride (1200 mg/kg, intraperitoneal injection, measurement 16 hr after injection) was significantly (over twofold) increased (Kl). These apparently paradoxical effects can be explained, however, by release of antioxidants from cells undergoing necrosis. Increase in TAC after intensive physical exercise also may be a marker of tissue... 

Understandably, there are examples of oxygen-tolerant cell lines which have much higher levels of constitutive antioxidant enzymes than normal [249]. The ability of other cells to protect themselves by means of antioxidant enzymes is limited by their biosynthetic response to oxidative stress. In vitro exposure to paraquat induces an increase in SOD and catalase activities in human and hamster fibroblasts [250,251]. In cultured HeLa cells, a chronic exposure to paraquat induces a simultaneous increase in Mn- and Cu/Zn-SOD activities in surviving cells [252], Interestingly, such cells have apparently acquired resistance to paraquat, and their higher level of SOD activities persists for many months following the exposure to paraquat. In Chinese hamster fibroblasts, a chronic exposure to H2O2 results in a 5-40-fold increase in catalase activity [253], which... 

McAinsh, M.R., Clayton, H., Mansfield, T.A., and Hetherington, A.M., 1996, Changes in Stomatal Behavior and Guard Cell Cytosolic Free Calcium in Response to Oxidative Stress. Plant Physiol. Ill 1031-1042. 

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