KCNH6 is essential for insulin secretion by regulating intracellular ER Ca2+ store

Abstract

Appropriate Ca²⁺ concentration in the endoplasmic reticulum (ER), modulating cytosolic Ca²⁺ signal, serves significant roles in physiological function of pancreatic β cells. To maintaining ER homeostasis, Ca²⁺ movement across the ER membrane is always accompanied by a simultaneous K⁺ flux in the opposite direction. KCNH6 was proven to modulate insulin secretion by controlling plasma membrane action potential duration and intracellular Ca²⁺ influx. Meanwhile, the specific function of KCNH6 in pancreatic β-cells remains unclear. In this study, we found that KCNH6 exhibited mainly ER localization and Kcnh6 β-cell-specific knockout (βKO) mice suffered from abnormal glucose tolerance and impaired insulin secretion in adulthood. ER Ca²⁺ store was overloaded in islets of βKO mice, which contributed to ER stress and ER stress-induced apoptosis in β cells. Next, we verified that ethanol treatment induced increases in ER Ca²⁺ store and apoptosis in pancreatic β cells, whereas adenovirus-mediated KCNH6 overexpression in islets attenuated ethanol-induced ER stress and apoptosis. In addition, tail-vein injections of KCNH6 lentivirus rescued KCNH6 expression in βKO mice, restored ER Ca²⁺ overload and attenuated ER stress in β cells, which further confirms that KCNH6 protects islets from ER stress and apoptosis. These data suggest that KCNH6 on the ER membrane may help to stabilize intracellular ER Ca²⁺ stores and protect β cells from ER stress and apoptosis. In conclusion, our study reveals the protective potential of KCNH6-targeting drugs in ER stress-induced diabetes.

Keywords: ER Ca2+ store; ER stress; KCNH6; apoptosis; insulin secretion.