ABSTRACT

Objective: Investigate the involvement of the fatty acids receptor GPR40 in the assembly and activation of NADPH oxidase and the implications on pancreatic β-cell function.

Methods: BRIN-BD11 β-cells were exposed to GPR40 agonist (GW9508) or linoleic acid in different glucose concentrations. Superoxide and H₂O₂ were analyzed, respectively, by DHE fluorescence and by fluorescence of the H₂O₂ sensor, roGFP2-Orp1. Protein contents of p47^phox in plasma membrane and cytosol were analyzed by western blot. NADPH oxidase role was evaluated by p22^phox siRNA or by pharmacological inhibition with VAS2870. NOX2 KO islets were used to measure total cytosolic calcium and insulin secretion.

Results: GW9508 and linoleic acid increased superoxide and H₂O₂ contents at 5.6 and 8.3 mM of glucose. In addition, in 5.6 mM, but not at 16.7 mM of glucose, activation of GPR40 led to the translocation of p47^phox to the plasma membrane. Knockdown of p22^phox abolished the increase in superoxide after GW9508 and linoleic acid. No differences in insulin secretion were found between wild type and NOX2 KO islets treated with GW9508 or linoleic acid.

Discussion: We report for the first time that acute activation of GPR40 leads to NADPH oxidase activation in pancreatic β-cells, without impact on insulin secretion.

摘要

目的：研究脂肪酸受体GPR40参与NADPH氧化酶的组装和激活及其对胰腺β细胞功能的影响。

方法：将BRIN-BD11β细胞暴露于不同葡萄糖浓度的GPR40激动剂（GW9508）或亚油酸中。通过DHE荧光和H ₂ O ₂传感器roGFP2-Orp1的荧光分别分析了超氧化物和H ₂ O ₂。用蛋白质印迹法分析质膜和细胞质中p47 ^phox的蛋白质含量。NADPH氧化酶的作用通过p22 ^phox siRNA或通过VAS2870的药理抑制来评估。NOX2 KO胰岛用于测量总胞质钙和胰岛素分泌。

结果： GW9508和亚油酸在葡萄糖分别为5.6和8.3 mM时增加了超氧化物和H ₂ O ₂含量。此外，在5.6 mM的葡萄糖中（但不是在16.7 mM的葡萄糖中），GPR40的激活导致p47 ^phox转运到质膜。在GW9508和亚油酸后，抑制p22 ^phox消除了超氧化物的增加。在野生型和用GW9508或亚油酸处理的NOX2 KO胰岛之间未发现胰岛素分泌的差异。

讨论：我们首次报道GPR40的急性激活会导致胰腺β细胞中NADPH氧化酶的激活，而不会影响胰岛素的分泌。