Voltage-gated K+ channel KCNQ1 regulates insulin secretion in MIN6 β-cell line

KCNQ1, located on 11p15.5, encodes a voltage-gated K+ channel with six transmembrane regions, and loss-of-function mutations in the KCNQ1 gene cause hereditary long QT syndrome. Recent genetic studies have identified that single nucleotide polymorphisms located in intron 15 of the KCNQ1 gene are strongly associated with type 2 diabetes and impaired insulin secretion. In order to understand the role of KCNQ1 in insulin secretion, we introduced KCNQ1 into the MIN6 mouse β-cell line using a retrovirus-mediated gene transfer system. In KCNQ1 transferred MIN6 cells, both the density of the KCNQ1 current and the density of the total K+ current were significantly increased. In addition, insulin secretion by glucose, pyruvate, or tolbutamide was significantly impaired by KCNQ1-overexpressing MIN6 cells. These results suggest that increased KCNQ1 protein expression limits insulin secretion from pancreatic β-cells by regulating the potassium channel current.

► KCNQ1 encodes a voltage-gated K+ channel, and loss-of-function mutations in the KCNQ1 gene cause hereditary long QT syndrome.
► Recent genome-wide association studies identified that polymorphisms of the KCNQ1 gene are associated with type 2 diabetes and impaired insulin secretion.
► In the present study, we introduced KCNQ1 into the MIN6 mouse β-cell line using a retrovirus-mediated gene transfer system.
► In KCNQ1-transferred MIN6 cells, the density of KCNQ1 current was significantly increased and insulin secretion by glucose, pyruvate, or tolbutamide was significantly impaired.
► These results indicate that KCNQ1 expression plays an important role in insulin secretion by pancreatic β-cells.