Bax cleavage implicates caspase-dependent H2O2-induced apoptosis of hepatocytes.

Abstract

Oxidative stress plays an important role in the development of ischemia/reperfusion (I/R)-induced apoptosis of hepatocytes. We aimed to examine the involvement of caspases and calpains in H2O2-induced hepatic cell apoptosis. TUNEL-positive apoptotic cells appeared in parallel with poly(ADP-ribose) polymerase (PARP) cleavage and procaspase-3 proteolysis by H2O2 treatment in a dose-dependent manner (250-1,000 micro M). Bcl-xL and intact Bax expression levels decreased when H2O2 was >250 micro M. The cleaved form of Bax appeared prior to caspase-3 activation, increasing in a dose-dependent manner. A pan-caspase inhibitor, Z-VAD-fmk, completely blocked H2O2-induced procaspase-3 proteolysis and PARP cleavage without changing Bax cleavage, but partially attenuated H2O2-induced apoptosis. Calpeptin, a calpain inhibitor, did not inhibit caspase-3 activation, Bax cleavage or apoptosis. Our results indicate that Bax cleavage is upstream signal of caspase-dependent apoptosis in hepatocytes exposed to H2O2, but not independent upon calpain. Molecular targeting of Bax cleavage may allow the development of strategies to prevent hepatic I/R injury.

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@article{Tamura2003BaxCI, title={Bax cleavage implicates caspase-dependent H2O2-induced apoptosis of hepatocytes.}, author={Hiroaki Tamura and Akira Ohtsuru and Yukio Kamohara and Hikaru Fujioka and Katsuhiko Yanaga and Takashi Kanematsu and Shunichi Yamashita}, journal={International journal of molecular medicine}, year={2003}, volume={11 3}, pages={369-74} }