PINK1 and Parkin Ameliorate the Loss of Motor Activity and Mitochondrial Dysfunction Induced by Peripheral Neuropathy-Associated HSPB8 Mutants in Models.

Charcot-Marie-Tooth disease (CMT) is a group of inherited peripheral nerve disorders characterized by progressive muscle weakness and atrophy, sensory loss, foot deformities and steppage gait. Missense mutations in the gene encoding the small heat shock protein HSPB8 (HSP22) have been associated with hereditary neuropathies, including CMT. HSPB8 is a member of the small heat shock protein family sharing a highly conserved α-crystallin domain that is critical to its chaperone activity. In this study, we modeled mutant-induced neuropathies in . The overexpression of human HSPB8 mutants in neurons produced no significant defect in fly development but led to a partial reduction in fly lifespan. Although these mutant genes failed to induce sensory abnormalities, they reduced the motor activity of flies and the mitochondrial functions in fly neuronal tissue. The motor defects and mitochondrial dysfunction were successfully restored by and , which are Parkinson's disease-associated genes that have critical roles in maintaining mitochondrial function and integrity. Consistently, kinetin riboside, a small molecule amplifying PINK1 activity, also rescued the loss of motor activity in our mutant model.