Glucose enhances collectrin protein expression in insulin-producing MIN6 beta cells

Collectrin is a novel target gene of hepatocyte nuclear factor-1alpha in pancreatic beta-cells and controls insulin exocytosis. Although glucose is known to stimulate the expression of genes of the insulin secretory pathway, there is no information on how glucose regulates collectrin expression. We investigated the effects of glucose on the expression of collectrin in MIN6 beta-cell line. Glucose, in a dose-dependent manner, increased collectrin protein levels without changing collectrin mRNA levels and protein stability, indicating that glucose stimulation of collectrin protein expression is primarily mediated at a translational level. Although mannose and pyruvate also increased collectrin protein expression level, neither 2-deoxyglucose, mitochondrial fuels leucine and glutamate, sulphonylurea nor Ca(2+) channel blockers, mimicked the effects of glucose. These data indicate the involvement of mitochondrial TCA cycle intermediates, distal to pyruvate, in the regulation of collectrin protein expression in beta-cells.