Clip R-59: a novel regulator of Akt signaling

描述（由申请人提供）：我们研究了Akt，它是PI 3 K的直接效应子，也是胰岛素代谢作用的主要介质。在这些研究的过程中，我们分离了ClipR-59，其表达在脂肪细胞分化过程中升高，在肥胖发展过程中降低，作为Akt相互作用蛋白。ClipR-59不涉及Akt激活。相反，它调节Akt活化后的Akt细胞区室化，特别是Akt膜缔合。ClipR-59对Akt膜结合的调节对于葡萄糖转运至关重要，如通过以下发现所证明的：ClipR-59的强制表达促进脂肪细胞葡萄糖转运，而ClipR-59的沉默损害脂肪细胞葡萄糖转运。脂肪细胞葡萄糖摄取对于维持全身葡萄糖稳态是必不可少的。由于肥胖症的流行，II型糖尿病已成为流行病和主要的公共卫生负担。鉴于ClipR-59与Akt相互作用并调节葡萄糖转运，因此有必要对ClipR-59进行进一步研究。我们目前的研究表明，a）ClipR-59在小鼠脂肪组织中的表达导致脂肪量减少和葡萄糖耐量增加，这表明ClipR-59可能在维持全身葡萄糖稳态中起作用; B）可能由蛋白棕榈酰转移酶DHHC 17介导的ClipR-59的棕榈酰化对于ClipR-59调节Akt细胞膜结合是关键的，暗示DHHC 17对ClipR-59棕榈酰化的调节构成ClipR-59调节Akt信号传导的重要机制;和c）ClipR-59与AS 160复合，AS 160是连接胰岛素信号传导和Glut 4囊泡的Rab-GAP蛋白。由于ClipR-59也直接与Akt相互作用，因此ClipR-59可能作为支架蛋白将Akt信号传导连接到AS 160。为了进一步研究ClipR-59的功能和调控，我们提出了以下具体问题的实验：1。确定脂肪组织中ClipR-59的强制表达对全身葡萄糖稳态以及肥胖、胰岛素抵抗和糖尿病的发展和进展的影响; 2.通过调节ClipR-59棕榈酰化来确定蛋白棕榈酰转移酶DHHC 17在Akt信号传导和脂肪细胞葡萄糖转运中的作用;以及3.确定ClipR-59和AS 160在脂肪细胞葡萄糖转运中相互作用的功能重要性。总体而言，本文提出的研究将证明ClipR-59如何调节全身葡萄糖稳态和脂肪细胞功能，从而深入了解特定Akt信号在胰岛素作用中的重要性。

DESCRIPTION (provided by applicant): We have studied Akt, the direct effector of PI3K and the primary mediator of insulin's metabolic actions. In the course of those studies, we isolated ClipR-59, whose expression is elevated during adipocyte differentiation and decreased during development of obesity, as an Akt interaction protein. ClipR-59 does not involve Akt activation. Instead, it modulates Akt cellular compartmentalization following Akt activation, in particular, Akt membrane association. The regulation of Akt membrane association by ClipR-59 is critical for glucose transport, as evidenced by the finding that forced expression of ClipR-59 promotes, whereas silencing of ClipR-59 impairs, adipocyte glucose transport. Adipocyte glucose uptake is essential for the maintenance of whole-body glucose homeostasis. Due to the prevalence of obesity, type II diabetes has become epidemic and a major public health burden. Given that ClipR-59 interacts with Akt and regulates glucose transport, further studies of ClipR-59 are warranted studies. Our current studies indicated that a) expression of ClipR-59 in adipose tissue in mice results in reduced fat mass and increased glucose tolerance, an indication that ClipR-59 might play a role in maintaining whole-body glucose homeostasis; b) palmitoylation of ClipR-59, likely mediated by protein palmitoyltransferase DHHC17, is critical for ClipR-59 to modulate Akt cellular membrane association, implying that regulation of ClipR-59 palmitoylation by DHHC17 constitutes an important mechanism by which ClipR-59 modulates Akt signaling; and c) ClipR-59 is complexed with AS160, a Rab-GAP protein that connects insulin signaling and Glut4 vesicles. Because ClipR-59 also interacts directly with Akt, ClipR-59 may function as a scaffold protein to connect Akt signaling to AS160. To further study the function and regulation of ClipR-59, we proposed the experiments to address following specific questions: 1. Determine the impact of forced expression of ClipR-59 in adipose tissue on whole-body glucose homeostasis and on the development and progression of obesity, insulin resistance, and diabetes; 2. Determine the role of protein palmitoyltransferase DHHC17 in Akt signaling and adipocyte glucose transport by modulating ClipR-59 palmitoylation; and 3. Determine the functional importance of the interaction between ClipR-59 and AS160 in adipocyte glucose transport. Overall, the studies proposed here will demonstrate that how specified Akt insulin signaling by ClipR-59 modulates whole body glucose homeostasis and adipocyte function thereby, providing insight knowledge into the importance of specified Akt signaling in insulin action.