VDAC phosphorylation, a lipid sensor influencing the cell fate

The voltage-dependent anion channel (VDAC) or porin is a major membrane protein integrated into the mitochondrial outer membrane in eukaryotes. It is encoded as three isoforms (VDAC1 to 3), which play differential roles in metabolism and cell death. As a channel, VDAC mediates metabolites, ions and water movements through the outer membrane in physiological conditions, but it can also participate to mitochondrial membrane permeabilization, an apoptotic checkpoint in stress and pathological conditions. Indeed, due to its subcellular location, VDAC interacts with many molecules as diverse as NAD+, lipids and cytosolic proteins such as hexokinase, tubulin, GSK3, Bax and Bcl-2 family members and mitochondrial proteins, such as the adenine nucleotide translocase (ANT). All these interactions can influence VDAC role in cell fate determination. In the recent past, major efforts focused on VDAC1 channel function and regulation by calcium and reactive oxygen species, and comparatively, fewer studies have been undertaken on VDAC2 and 3 and their pathophysiological involvement. Here, we review recent insights into the role of VDAC isoforms in cell death, and its regulation by phosphorylation or protein-lipid interactions and discuss the putative consequences of this post-translational modification on cell fate, notably in the context of lipid accumulation. This might have important implications for the understanding of basic mechanisms of mitochondrial lipid sensing and might contribute to define a novel therapeutic target for future investigation.