TALK-1-mediated alterations of β-cell mitochondrial function and insulin secretion impair glucose homeostasis on a diabetogenic diet

Summary

Mitochondrial Ca²⁺ ([Ca²⁺]_m) homeostasis is critical for β-cell function and becomes disrupted during the pathogenesis of diabetes. [Ca²⁺]_m uptake is dependent on elevations in cytoplasmic Ca²⁺ ([Ca²⁺]_c) and endoplasmic reticulum Ca²⁺ ([Ca²⁺]_ER) release, both of which are regulated by the two-pore domain K⁺ channel TALK-1. Here, utilizing a novel β-cell TALK-1-knockout (β-TALK-1-KO) mouse model, we found that TALK-1 limited β-cell [Ca²⁺]_m accumulation and ATP production. However, following exposure to a high-fat diet (HFD), ATP-linked respiration, glucose-stimulated oxygen consumption rate, and glucose-stimulated insulin secretion (GSIS) were increased in control but not TALK1-KO mice. Although β-TALK-1-KO animals showed similar GSIS before and after HFD treatment, these mice were protected from HFD-induced glucose intolerance. Collectively, these data identify that TALK-1 channel control of β-cell function reduces [Ca²⁺]_m and suggest that metabolic remodeling in diabetes drives dysglycemia.