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. Unlike
VDAC1 and VDAC2, the outer mitochondrial membrane porin 3 exhibits unique biophysical features that suggest
unknown cellular functions. Electrophysiological studies on VDAC3 carrying selective cysteine mutations and
mass spectrometry data about the redox state of such sulfur containing amino acids are consistent with a putative
involvement of isoform 3 in mitochondrial ROS homeostasis. Here, we thoroughly examined this issue and
provided for the first time direct evidence of the role of VDAC3 in cellular response to oxidative stress. Depletion
of isoform 3 but not isoform 1 significantly exacerbated the cytotoxicity of redox cyclers such as menadione and
paraquat, and respiratory complex I inhibitors like rotenone, promoting uncontrolled accumulation of mitochondrial
free radicals. High-resolution respirometry of transiently transfected HAP1-?VDAC3 cells expressing
the wild type or the cysteine-null mutant VDAC3 protein, unequivocally confirmed that VDAC3 cysteines are
indispensable for protein ability to counteract ROS-induced oxidative stress.