HSP40 Ameliorates Impairment of Insulin Secretion by Inhibiting Huntingtin Aggregation in a HD Pancreatic β Cell Model

Diabetes frequently develops in Huntington’s disease patients. Here, we found that mutant huntingtin forms aggregates in the cytoplasm and reduces insulin secretion from huntingtin transfected pancreatic β cell lines, NIT-1 cells. Activity of the pro-survival factor, Akt, is enhanced in these cells, which might improve the maintenance of insulin content. Overexpression of heat shock protein 40 (HSP40) inhibits aggregation, reverses impaired insulin release, and blocks the enhancement of Akt activity. These results suggest that impairment of β cells is mostly linked with the aggregate formation of mutant huntingtin, and that HSP40 ameliorates the malfunction of pancreatic β cells by inhibiting aggregation.