Mitochondrial succinate dehydrogenase is involved in stimulus-secretion coupling and endogenous ROS formation in murine beta cells
Mitochondrial succinate dehydrogenase is involved in stimulus-secretion coupling and endogenous ROS formation in murine beta cells
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DOI：
10.1007/s00125-015-3577-9
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发表时间：
2015-07-01
期刊：
影响因子：
8.2
通讯作者：
Duefer, Martina
中科院分区：
文献类型：
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作者：
Edalat, Armin;Schulte-Mecklenbeck, Philipp;Duefer, Martina
目的/假设产生还原当量是营养素刺激胰岛素分泌的先决条件。线粒体琥珀酸脱氢酶（SDH）在线粒体能量供应方面具有双重功能：（1）该酶是线粒体呼吸链的一部分;（2）它在克雷布斯循环中催化琥珀酸氧化为富马酸。本研究的目的是阐明SDH在β细胞刺激-分泌偶联（SSC）中的意义。活性氧（ROS）和胞浆Ca 2+浓度结果3-硝基丙酸（3-NPA）对C57 Bl/6 N小鼠胰岛细胞SDH的抑制作用明显高于对照组（P <0.05），而对C57 Bl/6 N小鼠胰岛细胞SDH的抑制作用明显低于对照组（P <0.05）。或富马酸单乙酯（MEF）减少葡萄糖刺激的胰岛素分泌。ATP敏感性K+通道（K-ATP通道）的抑制部分阻止了这种效应，而超氧化物歧化酶模拟物（TEMPO和mito-TEMPO）或核因子红细胞2相关因子2（Nrf-2）介导的抗氧化酶（奥替普拉，叔丁基羟基醌）上调的抗氧化防御增强并没有减少3-NPA的抑制作用。阻断SDH可降低葡萄糖刺激的细胞内FADH（2）浓度的增加，而不改变NAD（P）H。此外，3-NPA和MEF显著降低葡萄糖诱导的线粒体膜电位超极化，表明ATP产生减少。因此，葡萄糖刺激的[Ca 2 +]（c）升高显著延迟和降低。急性应用3-NPA中断葡萄糖驱动的[Ca 2 +]振荡（c）。3-NPA本身并没有提高细胞内ROS，而是阻止葡萄糖诱导的ROS accumulation.Conclusions/interpretation SDH是胰岛素分泌和ROS产生的重要调节因子。SDH的抑制中断了膜电位依赖性SSC，表明线粒体FAD/FADH（2）稳态在维持血液动力学控制中起着关键作用。
Aims/hypothesis Generation of reduction equivalents is a prerequisite for nutrient-stimulated insulin secretion. Mitochondrial succinate dehydrogenase (SDH) fulfils a dual function with respect to mitochondrial energy supply: (1) the enzyme is part of mitochondrial respiratory chains; and (2) it catalyses oxidation of succinate to fumarate in the Krebs cycle. The aim of our study was to elucidate the significance of SDH for beta cell stimulus-secretion coupling (SSC).Methods Mitochondrial variables, reactive oxygen species (ROS) and cytosolic Ca2+ concentration ([Ca2+](c)) were measured by fluorescence techniques and insulin release by radioimmunoassay in islets or islet cells of C57Bl/6N mice.Results Inhibition of SDH with 3-nitropropionic acid (3-NPA) or monoethyl fumarate (MEF) reduced glucose-stimulated insulin secretion. Inhibition of the ATP-sensitive K+ channel (K-ATP channel) partly prevented this effect, whereas potentiation of antioxidant defence by superoxide dismutase mimetics (TEMPOL and mito-TEMPO) or by nuclear factor erythroid 2-related factor 2 (Nrf-2)-mediated upregulation of antioxidant enzymes (oltipraz, tert-butylhydroxyquinone) did not diminish the inhibitory influence of 3-NPA. Blocking SDH decreased glucose-stimulated increase in intracellular FADH(2) concentration without alterations in NAD(P)H. In addition, 3-NPA and MEF drastically reduced glucose-induced hyperpolarisation of mitochondrial membrane potential, indicative of decreased ATP production. As a consequence, the glucose-stimulated rise in [Ca2+](c) was significantly delayed and reduced. Acute application of 3-NPA interrupted glucose-driven oscillations of [Ca2+](c). 3-NPA per se did not elevate intracellular ROS, but instead prevented glucose-induced ROS accumulation.Conclusions/interpretation SDH is an important regulator of insulin secretion and ROS production. Inhibition of SDH interrupts membrane-potential-dependent SSC, pointing to a pivotal role of mitochondrial FAD/FADH(2) homeostasis for the maintenance of glycaemic control.