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  • Title: Roles of Ras-Erk in apoptosis of PC12 cells induced by trophic factor withdrawal or oxidative stress.
    Author: Jiang H, Zhang L, Koubi D, Kuo J, Groc L, Rodriguez AI, Hunter TJ, Tang S, Lazarovici P, Gautam SC, Levine RA.
    Journal: J Mol Neurosci; 2005; 25(2):133-40. PubMed ID: 15784961.
    Abstract:
    To understand the role of Ras-MAPK (mitogen-activated protein kinase) in trophic factor withdrawal- and oxidative stress-induced apoptotic cell death processes, undifferentiated rat pheochromocytoma PC12 cells and a PC12 variant cell line stably expressing the Ras dominant-negative mutant (M-M17-26) were subjected to serum withdrawal in the absence or presence of H2O2 treatment. The extent of cell death was analyzed by lactate dehydrogenase release, internucleosomal DNA fragmentation, and caspase-3 assays. Both serum withdrawal and H2O2 treatment induced apoptotic cell death in PC12 cells, and the extent of cell death was greatly enhanced in M-M17-26 cells. DNA fragmentation induced by serum withdrawal or H2O2 treatment was blocked completely by a general caspase inhibitor, Z-VAD-FMK. A selective MAPK kinase inhibitor, U0126, blocked the H2O2-induced phosphorylation of Erk1/2 (extracellular signal-regulated kinase) in PC12 cells and increased the levels of active caspase-3 in M-M17-26 under serum withdrawal or H2O2 treatment. In addition, the short-term H2O2 treatment (5-30 min) was sufficient to cause DNA fragmentation in M-M17-26 cells even though H2O2 was removed and cells were incubated in regular growth medium with complete serum for 24 h. However, similar, short-term H2O2 treatment of PC12 cells did not induce DNA fragmentation 24 h later. These results suggest that the Ras-Erk pathway is critical in mediating protection against apoptotic cell death induced by either trophic factor withdrawal or increased oxidative stress.
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