Abstract
Here, we demonstrate that the voltage-gated proton channel Hv1 represents a regulatory mechanism for insulin secretion of pancreatic islet β cell. In vivo, Hv1-deficient mice display hyperglycemia and glucose intolerance due to reduced insulin secretion, but normal peripheral insulin sensitivity. In vitro, islets of Hv1-deficient and heterozygous mice, INS-1 (832/13) cells with siRNA-mediated knockdown of Hv1 exhibit a marked defect in glucose- and K+-induced insulin secretion. Hv1 deficiency decreases both insulin and proinsulin contents, and limits glucose-induced Ca2+ entry and membrane depolarization. Furthermore, loss of Hv1 increases insulin-containing granular pH and decreases cytosolic pH. In addition, histologic studies show a decrease in β cell mass in islets of Hv1-deficient mice. Collectively, our results indicate that Hv1 supports insulin secretion in the β cell by calcium entry, membrane depolarization and intracellular pH regulation.
SIGNIFICANCE STATEMENT The voltage-gated proton channel Hv1 is highly expressed in insulin-containing granules in pancreatic β cells. Hv1 supports insulin secretion in the β cell by calcium entry, membrane depolarization and regulation of intragranular and cytosolic pH, which represents a regulatory mechanism for insulin secretion of pancreatic islet β cell. Our research demonstrates that Hv1 expressed in β cell is required for insulin secretion and maintains glucose homeostasis, and reveals a significant role for the proton channel in the modulation of pancreatic β cell function.
