Voltage Dependent Anion Channel 3 (VDAC3) protects mitochondria from oxidative stress

Unraveling the role of VDAC3 within living cells is challenging and still requires a definitive answer. UnlikeVDAC1 and VDAC2, the outer mitochondrial membrane porin 3 exhibits unique biophysical features that suggestunknown cellular functions. Electrophysiological studies on VDAC3 carrying selective cysteine mutations andmass spectrometry data about the redox state of such sulfur containing amino acids are consistent with a putativeinvolvement of isoform 3 in mitochondrial ROS homeostasis. Here, we thoroughly examined this issue andprovided for the first time direct evidence of the role of VDAC3 in cellular response to oxidative stress. Depletionof isoform 3 but not isoform 1 significantly exacerbated the cytotoxicity of redox cyclers such as menadione andparaquat, and respiratory complex I inhibitors like rotenone, promoting uncontrolled accumulation of mitochondrialfree radicals. High-resolution respirometry of transiently transfected HAP1-?VDAC3 cells expressingthe wild type or the cysteine-null mutant VDAC3 protein, unequivocally confirmed that VDAC3 cysteines areindispensable for protein ability to counteract ROS-induced oxidative stress.