Transfection of mGSTA4 in HL-60 cells protects against 4-hydroxynonenal-induced apoptosis by inhibiting JNK-mediated signaling

The mammalian alpha-class glutathione S-transferase (GST) isozymes mGSTA4-4 , rGSTA4-4, and hGSTA4-4 are known to utilize 4-hydroxynonenal (4HNE) as a preferred substrate. During the present studies, we have examined the effec t of transfecting human myeloid HL-60 cells with mGSTA4, on 4-HNE-induced a poptosis and the associated signaling mechanisms. Results of these studies show that treatment of the wild-type or vector-only-transfected HL-60 cells with 20 muM 4-HNE caused apoptosis within 2 h. The cells transfected with mGSTA4 did not undergo apoptosis under these conditions even after 4 h. In the wild-type and vector-transfected cells, apoptosis was preceded by JNK a ctivation and c-Jun phosphorylation within 30 min, and an increase in AP-1 binding within 2 h of treatment with 20 muM 4-HNE. In mGSTA4-transfected ce lls, JNK activation and c-Jun phosphorylation were observed after I h, and increased AP-1 binding was observed after 8 h under these conditions. In th e control cells, 20 muM 4-HNE caused caspase 3 activation and poly(ADP-ribo se) polymerase cleavage within 2 h, while in mGSTA4-transfected cells, a le sser degree of these effects was observed even after 8 h. Transfection with mGSTA4 also provided protection to the cells from 4-HNE and doxorubicin cy totoxicity (1.6- and 2.6-fold, respectively). These results show that 4-HNE mediates apoptosis through its effects on JNK and caspase 3, and that 4-HN E metabolizing GST isozyme(s) may be important in the regulation of this pa thway of oxidative-stress-induced apoptosis. (C) 2001 Academic Press.