Low lactate dehydrogenase and high mitochondrial glycerol phosphate dehydrogenase in pancreatic beta-cells. Potential role in nutrient sensing.
Low lactate dehydrogenase and high mitochondrial glycerol phosphate dehydrogenase in pancreatic beta-cells. Potential role in nutrient sensing.
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DOI：
10.1016/s0021-9258(17)37629-9
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发表时间：
1994-02
期刊：
影响因子：
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通讯作者：
N. Sekine;V. Cirulli;R. Regazzi;L. Brown;E. Giné;J. Tamarit-Rodriguez;Milena Girotti;S. Marie;M. MacDonald;C. Wollheim;G. Rutter;G. Rutter
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文献类型：
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作者：
N. Sekine;V. Cirulli;R. Regazzi;L. Brown;E. Giné;J. Tamarit-Rodriguez;Milena Girotti;S. Marie;M. MacDonald;C. Wollheim;G. Rutter;G. Rutter
在纯化的大鼠胰岛β-和非β-细胞、β-细胞系和肝细胞中检查了胰岛素分泌方面的营养代谢。在葡萄糖敏感性INS-1细胞系（15.7）和β细胞（22.3）中，乳酸脱氢酶（LDH）活性（nanomoles.min-1.mg protein-1）显著较低。因此，β细胞LDH分别比胰岛非β、肝脏、HIT-T15和RINm 5 F细胞低8倍、122倍、17倍和136倍。β-或INS-1细胞的质膜乳酸转运活性比其他细胞类型低3-10倍。相反，线粒体甘油磷酸脱氢酶仅在β-和INS-1细胞中强烈表达。使用INS-1细胞作为天然β-细胞的模型来探索这些发现对营养素识别的意义。葡萄糖刺激的乳酸输出和葡萄糖利用率，分别为12-和5-倍低INS-1比RINm 5 F细胞。在INS-1细胞中，每个过程都被呼吸链抑制剂完全阻断，而在RINm 5 F细胞中，葡萄糖利用几乎没有受到影响，乳酸输出受到刺激。葡萄糖氧化在INS-1细胞中占总利用率的73%，但在RINm 5 F细胞中仅占9%。葡萄糖氧化的绝对速率和线粒体NAD（P）还原的程度在两种细胞类型中相似，葡萄糖刺激INS-1细胞胰岛素分泌1.9倍，RINm 5 F细胞胰岛素分泌1.4倍。线粒体底物琥珀酸单甲酯、丙酮酸和亮氨酸各自触发INS-1细胞中的分泌。因此，LDH、质膜乳酸转运和线粒体甘油磷酸脱氢酶活性的平衡在β-和INS-1细胞葡萄糖识别中似乎是重要的，以确保线粒体氧化是糖酵解产生的丙酮酸和NADH的主要命运。糖酵解与线粒体氧化的紧密耦合解释了β细胞中不存在克拉布特里和巴斯德效应。
Nutrient metabolism was examined with regard to insulin secretion in purified rat islet beta- and non-beta-cells, beta-cell lines, and hepatocytes. Lactate dehydrogenase (LDH) activity (nanomoles.min-1.mg protein-1) was remarkably low in the glucose-sensitive INS-1 cell line (15.7) and in beta-cells (22.3). Thus, beta-cell LDH was respectively 8-, 122-, 17-, and 136-fold lower than in islet non-beta, liver, HIT-T15, and RINm5F cells. Plasma membrane lactate transport activity was 3-10-fold lower in beta- or INS-1 cells than in the other cell types. Conversely, mitochondrial glycerol phosphate dehydrogenase was strongly expressed only in beta- and INS-1 cells. The significance of these findings to nutrient recognition was explored using INS-1 cells as a model of native beta-cells. Glucose-stimulated lactate output and glucose utilization were, respectively, 12- and 5-fold lower in INS-1 than in RINm5F cells. Each process was entirely blocked by respiratory chain inhibitors in INS-1 cells, whereas glucose utilization was barely affected and lactate output stimulated in RINm5F cells. Glucose oxidation represented 73% of total utilization in INS-1 cells, but only 9% in RINm5F cells. Absolute rates of glucose oxidation, and the extent of mitochondrial NAD(P) reduction, were similar in the two cell types, and glucose stimulated insulin secretion 1.9-fold in INS-1 and 1.4-fold in RINm5F cells. The mitochondrial substrates, monomethyl succinate, pyruvate, and leucine, each triggered secretion in INS-1 cells. The balance of LDH, plasma membrane lactate transport, and mitochondrial glycerol phosphate dehydrogenase activities therefore appear to be important in beta- and INS-1 cell glucose recognition to ensure that mitochondrial oxidation is the principle fate of pyruvate and NADH produced by glycolysis. The resultant close coupling of glycolysis with mitochondrial oxidation explains the absence in beta-cells of Crabtree and Pasteur effects.