Apoptosis in raw 264.7 cells exposed to 4-hydroxy-2-nonenal: Dependence oncytochrome c release but not p53 accumulation

The toxic reactive aldehyde lipid peroxidation byproduct 4-hydroxy-2-nonena l (HNE) is thought to be a major contributor to oxidant stress-mediated cel l injury. HNE induced apoptosis in RAW 264.7 murine macrophage cells in a d ose-dependent manner within 6-8 h after exposure. Expression of the antiapo ptotic protein Bcl-2 in stably transfected RAW 264.7 cells prevented HNE-in duced internucleosomal DNA fragmentation and apoptosis. and these cells res ume growth after a temporary (24-48 h) growth delay. While parental RAW 264 .7 cells released mitochondrial cytochrome c within 3 h after HNE exposure, expression of Bcl-2 prevented cytochrome c release. In control cells, p53 protein levels peaked at 6-9 h after HNE exposure and then declined, while in Bcl-2 expressing cells, p53 levels were maximal at 6-9 h and remained el evated up to 96 h. Expression of SV40 large T-antigen, which forms a stable complex with p53 protein, via stable transfection-blocked transactivation of the p53-regulated gene p21(WAF1/CIP1), hut did not affect induction of a poptosis by HNE. suggesting that p53 function is not important in HNE-induc ed apoptosis. These results suggest that cytochrome c release, but not p53 accumulation, plays an essential role in HNE-induced apoptosis in RAW 264.7 cells. (C) 2001 Elsevier Science Inc.