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[Involvement of Diacylglycerol Kinase on the Regulation of Insulin Secretion in Pancreatic β-Cells during Type 2 Diabetes].

par Kaneko, Yukiko;Sawatani, Toshiaki ;Ishikawa, Tomohisa
Référence Yakugaku zasshi, 142, 5, page (457-463)
Publication Publié, 2022

Article révisé par les pairs

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Résumé :

Depression of lipid metabolism in β-cells has been indicated to be one of the causes of impaired insulin secretion in type 2 diabetes. Diacylglycerol (DAG) is an important lipid mediator and is known to regulate insulin secretion in pancreatic β-cells. Intracellular DAG accumulation is involved in β-cell dysfunction in the pathogenesis of type 2 diabetes; thus, the regulation of intracellular DAG levels is likely important for maintaining the β-cell function. We focused on diacylglycerol kinases (DGKs), which strictly regulate intracellular DAG levels, and analyzed the function of type I DGKs (DGKα, γ), which are activated by intracellular Ca2+ and expressed in the cytoplasm, in β-cells. The suppression of the DGKα and γ expression decreased the insulin secretory response, and the decreased expression of DGKα and γ was observed in islets of diabetic model mice. In the pancreatic β-cell line MIN6, 1 μM R59949 (a type I DGK inhibitor) and 10 μM DiC8 (a cell permeable DAG analog) enhanced glucose-induced [Ca2+]i oscillation in a PKC-dependent manner, while 10 μM R59949 and 100 μM DiC8 suppressed [Ca2+]i oscillation and voltage-dependent Ca2+ channel activity in a PKC-independent manner. These results suggest that the intracellular accumulation of DAG by the loss of the DGKα and γ functions regulates insulin secretion in a dual manner depending on the degree of DAG accumulation. The regulation of the insulin secretory response through DAG metabolism by type I DGKs may change depending on the degree of progression of type 2 diabetes.