SWELL1 is a glucose sensor regulating β-cell excitability and systemic glycaemia

Insulin secretion is initiated by activation of voltage-gated Ca2+ channels (VGCC) to trigger Ca2+-mediated insulin vesicle fusion with the beta-cell plasma membrane. The firing of VGCC requires beta-cell membrane depolarization, which is regulated by a balance of depolarizing and hyperpolarizing ionic currents. Here, we show that SWELL1 mediates a swell-activated, depolarizing chloride current (I-Cl, (SWELL)) in both murine and human beta-cells. Hypotonic and glucose-stimulated beta-cell swelling activates SWELL1-mediated I-Cl,I- SWELL and this contributes to membrane depolarization and activation of VGCC-dependent intracellular calcium signaling. SWELL1 depletion in MIN6 cells and islets significantly impairs glucose-stimulated insulin secretion. Tamoxifen-inducible beta-cell-targeted Swell1 KO mice have normal fasting serum glucose and insulin levels but impaired glucose-stimulated insulin secretion and glucose tolerance; and this is further exacerbated in mild obesity. Our results reveal that beta-cell SWELL1 modulates insulin secretion and systemic glycaemia by linking glucose-mediated beta-cell swelling to membrane depolarization and activation of VGCC-triggered calcium signaling.