Reactive Oxygen Species and P38 Mapk Activate Bax to Induce Mitochondrial Cytochrome C Release and Apoptosis in Response to Malonate

Malonate, an inhibitor of mitochondrial complex II, is a widely used toxin to study neurodegeneration in Huntington’s disease and ischemic stroke. We have previously shown that malonate increased reactive oxygen species (ROS) production in human SH-SY5Y neuroblastoma cells, leading to oxidative stress, cytochrome-c release, and apoptotic cell death. Expression of a Green Fluorescent Protein-Bax fusion protein in SH-SY5Y neuroblastoma cells demonstrated a Bax redistribution from the cytosol to mitochondria after 12 – 24 h of malonate treatment that coincided with mitochondrial potential collapse and chromatin condensation. Inhibition of Bax translocation using furosemide, as well as Bax gene deletion afforded significant protection against malonate-induced apoptosis. Further experiments revealed that malonate induced a prominent increase in the level of activated p38 MAP kinase, and that treatment with the p38 MAP kinase inhibitor SKF86002 potently blocked malonate-induced Bax translocation and apoptosis. Treatment with vitamin E diminished ROS production, reduced the activation status of p38 MAP kinase, inhibited Bax translocation and protected against malonate-induced apoptosis. Our data suggest that malonate-induced ROS production and subsequent p38 MAP kinase activation mediates the activation of the pro-apoptotic Bax protein to induce mitochondrial membrane permeabilisation and neuronal apoptosis. This article has not been copyedited and formatted. The final version may differ from this version. Molecular Pharmacology Fast Forward. Published on December 15, 2006 as DOI: 10.1124/mol.106.030718 at A PE T Jornals on O cber 9, 2017 m oharm .aspeurnals.org D ow nladed from