SIGNALING MOLECULES IN STRESS-INDUCED APOPTOSIS

다국어 초록 (Multilingual Abstract)

It is well known that exposure of cells to various environmental stresses such as heat shock and oxidant, hypoxia, heavy metals, growth factors, death surface receptors and various chemicals, can induce apoptotic cell death. However, it is suggested that the apoptotic signaling pathways in response to various stresses are differnt. We investigated the cellular changes by heat shock, ceramide and oxident(H₂O₂ and diamide) in thermotolerant radiation induced fibrosarcoma cells(TR-RIF-1) which have elevated levels of heat shock proteins(hsps). Thermotolerant cells were significantly resistant to apoptosis induced by heat shock and diamide, but no differnt response to ceramide and H₂O₂. To elucidate these differences, the biochemical changes in cells exposed to various stresses were investigated: the extents of apoptosis, protein synthesis, hsp formation, activation of SAPK and ERK activation, no oxidation mediated, on the other hand, membrane disturbing agent ceramide and non-specific oxident H₂O₂ have different pathways as protein denaturants. Simultaneously, the oxidized proteins in cells exposed to oxidants were identified by labeling the active site of glyceraldehyde-3-phosphate dehydrogenase(GAPDH) is a target of oxidants and could be a turn on/off switch of cell death and survival. The cellular signaling mechanism in response to these oxidants were investigated by MALDI-TOF-MS and identified that vimentin, tubulin and 14-3-3 protein are involved in the apoptosis induced by protein denaturation and ROS formation by growth factors.
Rac 1 is one of the Rho family members, which acts as a molecular switch to control various cellular processes, including the reorganization of actin cytoskeleton, gene transcription, oncogenicity, cell cycle etc. It is also known that the activation of c-jun N-terminal kinase(JNK) by growth factor is mediated by Rac 1 and phosphoinositide 3-kinase(PI3K), the upstream regulator of rac 1. In this study, the relationship between heat shock responses and rac 1 has been examined. We used rat2, mouse fibroblast cells which permanently overexpress the dominant negative mutant, RacN17. We found that rat2 cells overexpressing RacN17 were tolerant to heat shock and the mechanism of (이후원문누락)