Small heat shock proteins (HSPBs) sequestration at the outer mitochondrial membrane abrogates oxidative stress induced intrinsic apoptosis by preventing the release of cytochrome c from the mitochondria.

Small heat shock proteins (HSPBs) are ATP-independent chaperones that are involved in maintaining the proteome integrity by preventing aberrant protein aggregation. They form highly dynamic, polydisperse oligomeric ensembles, and contain long intrinsically disordered regions. Experimental challenges posed by these aforementioned properties have greatly hindered our understanding of HSPBs. Unpublished work from our lab has shown that HSPBs execute an unexpected dual role in mitochondrial protein quality control. We found out that HSPBs are able to translocate to the mitochondrial intermembrane space (IMS) under basal condition where they prevent protein aggregation; however, after heat shock (42°C for 1 hour) to induce protein misfolding, they immediately translocate to the outer mitochondrial membrane (OMM) for a reason that is unknown. Remarkable is that a P182L mutant of HSPB1 (causing peripheral neuropathy) exhibits the enrichment of the HSPB1 protein on the OMM even under the basal condition, triggering mis-signaling of an unknown pathway that subsequently leads to mitochondrial dysfunctions. In this PhD proposal, I will systematically characterize the function of HSPBs on the OMM, identify their upstream regulators for immediate translocation to the OMM post heat shock and the turn of events following it, which is particularly relevant under different cellular states.

Keywords:INHERITED PERIPHERAL NEUROPATHIES, HEAT SHOCK PROTEINS, MITOCHONDRIA

Disciplines:Genetics, Molecular and cell biology not elsewhere classified, Cell physiology