AS160 Overexpression Protects Against β-Cell Failure in Hyperglycemic Mice by Interacting With HSPA8 to Regulate...

Insulin deficiency due to pancreatic β-cell loss and dysfunction is a key event in the pathogenesis of T1DM and a progressive driver of T2DM. This study aims to investigate the role of AS160 in regulating mitochondrial homeostasis and insulin secretion in pancreatic β-cells, and to elucidate the underlying molecular mechanism involving its interaction with HSPA8 and activation of PINK1-Parkin-mediated mitophagy.

Insulin and AS160 levels in islets were analyzed by immunofluorescence staining. β cell-specific AS160 overexpression mice were generated via lentivirus injection, and their metabolic phenotypes were characterized. In vitro, AS160 was overexpressed or knocked down to assess its impact on cell proliferation, insulin secretion, and mitochondrial function. AS160-interacting proteins were identified by immunoprecipitation-mass spectrometry (IP-MS).

AS160 expression was significantly decreased in islet and correlated positively with insulin levels in hyperglycemic mice. Specific overexpression of AS160 in β-cells exhibited novel protective effects for the islets and insulin levels in hyperglycemic mice. Mechanistically, AS160 overexpression in β-cells increased mitophagy and preserved mitochondrial biogenesis to maintain healthy mitochondrial homeostasis and insulin secretion. At the molecular level, HSPA8 was identified as a novel AS160-interacting protein that enhances PINK-dependent mitophagy. Knockdown of HSPA8 reversed the overexpression of AS160-induced mitophagy and mitochondrial biogenesis.

Collectively, this work identifies the AS160-HSPA8 interaction as a key mechanism that sustains mitochondrial homeostasis through regulating mitophagy and mitochondrial biogenesis, thus preserving β-cell mass and function. These findings suggest that AS160 emerges as a pivotal regulator of mitochondrial homeostasis in pancreatic β-cell in vivo.