Impaired Insulin Secretion by Diphenyleneiodium Associated with Perturbation of Cytosolic Ca2+ Dynamics in Pancreatic β-Cells
Impaired Insulin Secretion by Diphenyleneiodium Associated with Perturbation of Cytosolic Ca2+ Dynamics in Pancreatic β-Cells
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DOI：
10.1210/en.2008-0186
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发表时间：
2008-11-01
期刊：
影响因子：
4.8
通讯作者：
Iida, Mitsuo
中科院分区：
文献类型：
--
作者：
Imoto, Hirofumi;Sasaki, Nobuhiro;Iida, Mitsuo
胰岛表达产生超氧化物的烟酰胺腺嘌呤二核苷酸磷酸（NADPH）氧化酶系统，但其作用仍然未知。为了解决这一问题，我们研究了NADPH氧化酶抑制剂二苯乙炔（DPI）诱导的胰岛素分泌受损的机制。我们研究了DPI对大鼠胰岛和β细胞系RINm 5 F细胞中葡萄糖和非燃料刺激的胰岛素分泌、胰岛葡萄糖代谢和细胞内Ca 2+浓度（[Ca 2 +]（i））动态的影响。DPI在3.3mM葡萄糖下不影响胰岛素分泌，但完全抑制由16.7mM葡萄糖刺激的胰岛素分泌（对照百分比，9.2 +/-1.2%; P < 0.001）。DPI还通过高K+诱导的膜去极化抑制胰岛素释放（对照百分比，36.0 +/- 5.3%; P < 0.01）和蛋白激酶C活化（对照组30.2 ± 10.6%，P < 0.01）;对照组的百分比，在不存在细胞外Ca 2+的情况下为42.0 +/-4.7%，P < 0.01）。然而，DPI没有影响mastoparan诱导的胰岛素分泌在3.3和16.7 mM的葡萄糖在无钙条件下。DPI通过其对线粒体呼吸链中复合物I的已知抑制作用显著抑制胰岛葡萄糖氧化和ATP含量。另一方面，DPI改变了响应于高糖和膜去极化的[Ca 2 +]（i）动力学，并且DPI本身剂量依赖性地增加[Ca 2 +]（i）。DPI诱导的[Ca ~（2+）]（i）升高与胰岛素分泌的瞬时增加有关，并通过去除细胞外Ca ~（2+）、L型电压依赖性Ca ~（2+）通道阻滞剂、线粒体抑制剂或外源性加入0.1或1.0 μ M H_2O_2而减弱。我们的研究结果表明，DPI胰岛素分泌的损害涉及改变Ca 2+信号，这表明NADPH氧化酶可能调节β细胞中的Ca 2+信号。（内分泌学149：5391-5400，2008）
Pancreatic islets express the superoxide-producing nicotinamide adenine dinucleotide phosphate (NADPH) oxidase system, but its role remains unknown. To address this, we studied the mechanisms of impaired insulin secretion induced by diphenyleneiodium (DPI), an NADPH oxidase inhibitor. We investigated the effects of DPI on glucose- and nonfuel-stimulated insulin secretion, islet glucose metabolism, and intracellular Ca2+ concentration ([Ca2+](i)) dynamics in rat islets and beta-cell line RINm5F cells. DPI did not affect insulin secretion at 3.3 mM glucose but totally suppressed insulin secretion stimulated by 16.7 mM glucose ( percentage of control, 9.2 +/- 1.2%; P < 0.001). DPI also inhibited insulin release by high K+-induced membrane depolarization (percentage of control, 36.0 +/- 5.3%; P < 0.01) and protein kinase C activation (percentage of control, 30.2 +/- 10.6% in the presence of extracellular Ca2+, P < 0.01; percentage of control, 42.0 +/- 4.7% in the absence of extracellular Ca2+, P < 0.01). However, DPI had no effect on mastoparan-induced insulin secretion at 3.3 and 16.7 mM glucose under Ca2+-free conditions. DPI significantly suppressed islet glucose oxidation and ATP content through its known inhibitory action on complex I in the mitochondrial respiratory chain. On the other hand, DPI altered [Ca2+](i) dynamics in response to high glucose and membrane depolarization, and DPI per se dose-dependently increased [Ca2+](i). The DPI-induced [Ca2+](i) rise was associated with a transient increase in insulin secretion and was attenuated by removal of extracellular Ca2+, by L-type voltage-dependent Ca2+ channel blockers, by mitochondrial inhibitors, or by addition of 0.1 or 1.0 mu M H2O2 exogenously. Our results showed that DPI impairment of insulin secretion involved altered Ca2+ signaling, suggesting that NADPH oxidase may modulate Ca2+ signaling in beta-cells. (Endocrinology 149: 5391-5400, 2008)