cIAPs promote the proteasomal degradation of mutant SOD1 linked to familial amyotrophic lateral sclerosis.

Although the ubiquitin-proteasome system is believed to play an important role in the pathogenesis of familial amyotrophic lateral sclerosis (FALS), caused by mutations in Cu/Zn-superoxide dismutase 1 (SOD1), the mechanism of how mutant SOD1 protein is regulated in cells is still poorly understood. Here we have demonstrated that cellular inhibitor of apoptosis proteins (cIAPs) are specifically associated with FALS-linked mutant SOD1 (mSOD1) and that this interaction promotes the ubiquitin-dependent proteasomal degradation of mutant SOD1. By utilizing cumate inducible SOD1 cells, we also showed that knock-down or pharmacologic depletion of cIAPs leads to HO induced cytotoxicity in mSOD1 expressing cells. Altogether, our results reveal a novel role of cIAPs in FALS-associated mutant SOD1 regulation.