Meglasson M D, Smith K M, Nelson D, Erecinska M
Diabetes Research Center, University of Pennsylvania School of Medicine, Philadelphia 19104.
Am J Physiol. 1989 Jan;256(1 Pt 1):E173-8. doi: 10.1152/ajpendo.1989.256.1.E173.
It has been proposed that the alpha-glycerophosphate (alpha-GOP) shuttle plays a crucial role in regulation of glycolysis in beta-cells by linking reoxidation of cytosolic NADH to formation of ATP in the electron transport chain (J. Biol. Chem. 265: 8287, 1981). Direct evidence for this suggestion is still lacking, however. In this work the operation of the alpha-GOP shuttle was investigated in the insulin-secreting cell line HIT-T15. The constituent enzymes of the pathway were found to be present in HIT cells. Flavin-linked alpha-GOP dehydrogenase was associated with the mitochondrial fraction, whereas NAD+-dependent alpha-GOP dehydrogenase was localized in the cytosol. In the presence of amobarbital (used to preserve the function of the alpha-GOP shuttle under conditions where oxidation of NADH by the respiratory chain was blocked), glucose increased insulin secretion, O2 consumption, and the cell [ATP]/[ADP] when compared with amobarbital alone. These results indicate that the alpha-GOP shuttle contributes to ATP generation in HIT cells and that its activation may be necessary for the initiation of insulin secretion by glucose.
有人提出，α-甘油磷酸穿梭在β细胞糖酵解调节中起着关键作用，它将胞质NADH的再氧化与电子传递链中ATP的形成联系起来（《生物化学杂志》265:8287,1981）。然而，这一观点仍缺乏直接证据。在这项研究中，我们在胰岛素分泌细胞系HIT-T15中研究了α-甘油磷酸穿梭的运行情况。发现该途径的组成酶存在于HIT细胞中。黄素连接的α-甘油磷酸脱氢酶与线粒体部分相关，而NAD+依赖的α-甘油磷酸脱氢酶定位于胞质溶胶中。在存在异戊巴比妥（用于在呼吸链氧化NADH受阻的条件下维持α-甘油磷酸穿梭的功能）的情况下，与单独使用异戊巴比妥相比，葡萄糖增加了胰岛素分泌、氧气消耗和细胞内[ATP]/[ADP]比值。这些结果表明，α-甘油磷酸穿梭有助于HIT细胞中ATP的生成，其激活可能是葡萄糖引发胰岛素分泌所必需的。
