Accelerated metabolism and exclusion of 4-hydroxynonenal through inductionof RLIP76 and hGST5.8 is an early adaptive response of cells to heat and oxidative stress.

To explore the role of lipid peroxidation (LPG) products in the initial pha se of stress mediated signaling, we studied the effect of mild, transient o xidative or heat stress on parameters that regulate the cellular concentrat ion of 4-hydroxynonenal (4-HNE). When K562 cells were exposed to mild heat shock (42 degreesC, 30 min) or oxidative stress (50 mum H2O2,20 min) and al lowed to recover for 2 h, there was a severalfold induction of hGST5.8, whi ch catalyzes the formation of glutathione-4-HNE conjugate (GS-HNE), and RLI P76, which mediates the transport of GS-HNE from cells (Awasthi, S., Cheng, J., Singhal, S. S., Saini, M. K., Pandya, U., Pikula, S., Bandorowicz-Piku la, J., Singh, S. V., Zimniak, P., and Awasthi, Y. C. (2000) Biochemistry 3 9, 9327-9334). Enhanced LPO was observed in stressed cells, but the major a ntioxidant enzymes and HSP70 remained unaffected. The stressed cells showed higher GS-HNE-conjugating activity and increased efflux of GS-FINE. Stress -pre-conditioned cells with induced hGST5.8 and RLIP76 acquired resistance to 4-HNE and H2O2-mediated apoptosis by suppressing a sustained activation of c-Jun N-terminal kinase and caspase 3. The protective effect of stress p re-conditioning against apoptosis was abrogated by coating the cells with a nti-RLIP76 IgG, which inhibited the efflux of GS-HNE from cells, indicating that the cells acquired resistance to apoptosis by metabolizing and exclud ing 4-HNE at a higher rate. Induction of hGST5.8 and RLIP76 by mild, transi ent stress and the resulting resistance of stress-pre-conditioned cells to apoptosis appears to be a general phenomenon since it was not limited to K5 62 cells but was also evident in lung cancer cells, H-69, H-226, human leuk emia cells, HL-60, and human retinal pigmented epithelial cells. These resu lts strongly suggest a role of LPO products, particularly 4-HNE, in the ini tial phase of stress mediated signaling.