BAG6 deficiency induces mis‐distribution of mitochondrial clusters under depolarization

Accumulation of damaged mitochondria is implicated in a number of neurodegenerative disorders, including Parkinson's disease. Therefore, the machinery for mitochondrial quality control is important for the prevention of such diseases. It has been reported that Parkin‐ and p62/sequestosome 1 (SQSTM1)‐mediated clustering and subsequent elimination of damaged mitochondria (termed mitophagy) are critical for maintaining the quality of mitochondria under stress induced by uncoupling agents such as carbonyl cyanide m‐chlorophenyl hydrazone. However, the molecular mechanisms underlying mitochondrial translocation to the perinuclear region during mitophagy have not been adequately addressed to date. In this study, we found that BCL2‐associated athanogene 6 (BAG6; also known as BAT3 or Scythe) is required for this process. Indeed, RNA interference‐mediated depletion of endogenous BAG6 prevented Parkin‐dependent relocalization of mitochondrial clusters to the perinuclear cytoplasmic region, whereas BAG6 knockdown did not affect the translocation of Parkin and p62/SQSTM1 to the depolarized mitochondria and subsequent aggregation. These results suggest that BAG6 is essential for cytoplasmic redistribution, but not for clustering, of damaged mitochondria. Under depolarized conditions, damaged mitochondria form clusters in a Parkin‐ and p62‐dependent manner and accumulate at the perinuclear region. However, the molecular mechanism by which depolarized mitochondrial clusters translocate has not been elucidated yet. In this study, we found that BCL2‐associated athanogene 6 is responsible for translocation of mitochondrial clusters toward the perinuclear region of the cell.