Oleic acid interacts with GPR40 to induce Ca2+ signaling in rat islet β-cells:: mediation by PLC and L-type Ca2+ channel and link to insulin release
Oleic acid interacts with GPR40 to induce Ca2+ signaling in rat islet β-cells:: mediation by PLC and L-type Ca2+ channel and link to insulin release
复制标题
DOI：
10.1152/ajpendo.00035.2005
复制
发表时间：
2005-10-01
影响因子：
5.1
通讯作者：
Yada, T
中科院分区：
文献类型：
--
作者：
Fujiwara, K;Maekawa, F;Yada, T
长期以来，人们一直认为长链游离脂肪酸（FFA）通过涉及其在胰腺β细胞中代谢的机制刺激胰岛素分泌。最近，据报道，FFA作为GPR 40（G蛋白偶联受体）的内源性配体，在胰岛素瘤细胞系和大鼠胰岛中放大葡萄糖刺激的胰岛素分泌。然而，GPR 40在β细胞中的信号转导机制知之甚少。本研究的目的是阐明GPR 40相关的Ca 2+信号转导机制在大鼠胰腺β细胞。我们采用油酸（OA），一种对大鼠GPR 40具有高亲和力的FFA，并通过Fura 2荧光成像检查其对单个β细胞中胞质Ca 2+浓度（[Ca 2 +]（i））的影响。OA在1 - 10 μ M浓度依赖性增加[Ca 2 +]（i）在存在5.6，8.3，和11.2 mM，但不是2.8 mM，葡萄糖。在用靶向大鼠GPR 40 mRNA的小干扰RNA转染的β细胞中，在11.2 mM葡萄糖下OA诱导的[Ca 2 +]（i）增加受到抑制。磷脂酶C（PLC）抑制剂U 73122和新霉素、无钙条件和L型钙通道阻滞剂尼群地平也能抑制OA诱导的[Ca ~（2+）]（i）升高。此外，OA在8.3 mM葡萄糖下增加胰岛的胰岛素释放，PLC和L-型Ca 2+通道抑制剂可明显减弱OA的作用。这些结果表明，OA与GPR 40相互作用，通过PLC-和L-型Ca 2+通道介导的途径增加大鼠胰岛β细胞中的[Ca 2 +]（i），这可能与胰岛素释放有关。
It has long been thought that long-chain free fatty acids (FFAs) stimulate insulin secretion via mechanisms involving their metabolism in pancreatic beta-cells. Recently, it was reported that FFAs function as endogenous ligands for GPR40, a G protein-coupled receptor, to amplify glucose-stimulated insulin secretion in an insulinoma cell line and rat islets. However, signal transduction mechanisms for GPR40 in beta-cells are little known. The present study was aimed at elucidating GPR40-linked Ca2+ signaling mechanisms in rat pancreatic beta-cells. We employed oleic acid (OA), an FFA that has a high affinity for the rat GPR40, and examined its effect on cytosolic Ca2+ concentration ([Ca2+](i)) in single beta-cells by fura 2 fluorescence imaging. OA at 1 - 10 mu M concentration-dependently increased [Ca2+](i) in the presence of 5.6, 8.3, and 11.2 mM, but not 2.8 mM, glucose. OA-induced [Ca2+](i) increases at 11.2 mM glucose were inhibited in beta-cells transfected with small interfering RNA targeted to rat GPR40 mRNA. OA-induced [Ca2+](i) increases were also inhibited by phospholipase C (PLC) inhibitors, U73122 and neomycin, Ca2+-free conditions, and an L-type Ca2+ channel blocker, nitrendipine. Furthermore, OA increased insulin release from isolated islets at 8.3 mM glucose, and it was markedly attenuated by PLC and L-type Ca2+ channel inhibitors. These results demonstrate that OA interacts with GPR40 to increase [Ca2+](i) via PLC- and L-type Ca2+ channel-mediated pathway in rat islet beta-cells, which may be link to insulin release.