Role of Phospholipase D in Glut-4 translocation

描述（由申请方提供）：肌肉和脂肪组织中胰岛素刺激的葡萄糖摄取主要由胰岛素应答葡萄糖转运蛋白亚型Glut-4介导。在基础状态下，Glut-4缓慢循环，大部分蛋白质被隔离到细胞内储存位点。响应于胰岛素，Glut-4胞吐的速率变得显著增加，导致Glut-4在细胞表面的大量积累。最近的研究结果表明，这一易位过程可能是由磷脂酶D（PLD），膜相关酶，也被胰岛素激活的调节。PLD催化最丰富的膜磷脂--磷脂酰胆碱水解生成信号脂质磷脂酸（PA）。PA被认为具有多种细胞功能，包括促进膜囊泡运输。哺乳动物有两个PLD基因，PLD 1和PLD 2。我们最近表明，PLD 1促进融合的神经内分泌颗粒到质膜在调节胞吐和这两个基因促进调节胞吐肥大细胞含组胺颗粒。重要的是，控制这些分泌颗粒的融合机制与胰岛素刺激的Glut-4囊泡的质膜融合具有许多共同的特征，并且我们最近发现PLD 1和PLD 2的激活或抑制改变胰岛素刺激的Glut-4向质膜的转运。基于这些新的数据，我们建议系统地检查PLD的功能，作为一个关键的监管组成部分，在胰岛素刺激的运输的Glut-4的开发重建试验和建立PLD的作用，在生理相关的背景。

DESCRIPTION (provided by applicant): Insulin-stimulated glucose uptake in muscle and adipose tissue is primarily mediated by the insulin-responsive glucose transporter isoform, Glut-4. In the basal state, Glut-4 slowly cycles with the majority of the protein sequestered into intracellular storage sites. In response to insulin, the rate of Glut-4 exocytosis becomes markedly increased, resulting in a large accumulation of Glut-4 at the cell surface. Recent findings have suggested that this translocation process may be regulated by Phospholipase D (PLD), a membrane-associated enzyme that is also activated by insulin. PLD catalyzes the hydrolysis of phosphatidylcholine, the most abundant membrane phospholipid, to generate the signaling lipid phosphatidic acid (PA). PA has been proposed to have several cellular functions including the facilitation of membrane vesicle trafficking. There are two mammalian PLD genes, PLD1 and PLD2. We have recently shown that PLD1 facilitates the fusion of neuroendocrine secretory granules into the plasma membrane during regulated exocytosis and that both genes facilitate regulated exocytosis of mast cell histamine-containing granules. Importantly, the fusion mechanisms controlling these secretory granules have many features in common with the insulin-stimulated plasma membrane fusion of Glut-4 vesicles, and we have found recently that PLD1 and PLD2 activation or inhibition alters insulin-stimulated Glut-4 translocation to the plasma membrane. Based upon these novel data, we propose to examine systematically the function of PLD as a key regulatory component in the insulin-stimulated trafficking of Glut-4 by developing reconstitution assays and establishing the role of PLD in physiologically relevant contexts.