ACIDIC FIBROBLAST GROWTH-FACTOR ENHANCES PEROXYNITRITE-INDUCED APOPTOSIS IN PRIMARY MURINE FIBROBLASTS

Oxidative stress is considered a major mediator of apoptosis in severa l cellular systems. Peroxynitrite is a highly toxic oxidant formed by the reaction of nitric oxide with superoxide. Primary embryonic murine fibroblasts, exposed to 1 mM peroxynitrite, resulted in delayed cell death characterized by membrane blebbing, cytoplasmic shrinkage, nucle ar condensation, and DNA fragmentation that were more characteristic o f apoptosis than necrosis. In addition, both morphological alterations and DNA fragmentation were inhibited by the endonuclease inhibitor au rintricarboxylic acid. Pretreatment of fibroblasts with acidic fibrobl ast growth factor (FGF-1) markedly enhanced peroxynitrite-induced apop tosis, an observation restricted to immediate-early transcriptional an d activated tyrosine phosphorylation processes. FGF-1 pretreatment had no modulatory effect on cell death elicited by other reactive oxygen species, suggesting that enhancement of apoptosis involves a unique re lationship between peroxynitrite and the growth factor, Exposure of ce lls to peroxynitrite resulted in immediate tyrosine nitration of sever al polypeptides, including major targets with estimated molecular mass es of 62, 68, and 77 kDa. Pretreatment with FGF-1 did not alter target s of peroxynitrite-mediated tyrosine nitration, but rather increased t he total amount of this amino acid modification, Treatment with other reactive oxygen species failed to induce tyrosine nitration. Collectiv ely, these efforts demonstrate that FGF-1 transiently renders primary fibroblasts more sensitive to peroxynitrite-induced apoptosis, In addi tion, results presented here predict a pivotal role for FGF-1 and pero xynitrite-induced cytotoxicity during the resolution of inflammation a nd repair processes in vivo. (C) 1996 Academic Press, Inc.