Mitochondrial retrograde signaling to the endoplasmic-reticulum regulates unfolded protein responses

Unfolded protein response (UPRs) directs adaption or apoptosis depending on the severity of endoplasmic-reticulum (ER) stress. We found that apoptotic signaling by inositol requiring enzyme 1 alpha (IRE1 alpha), a transducer of UPRs, is suppressed by mitochondrial ubiquitin ligase MITOL/MARCH5 on ER-mitochondria contacts, suggesting that mitochondria regulate cell fate under ER stress.