protein kinase Dnu in regulated GLUT4 trafficking

胰岛素的基本作用是促进葡萄糖从血流中摄取到脂肪和肌肉的胰岛素反应组织。在此过程中，胰岛素主要通过刺激促进性葡萄糖转运蛋白同种型GLUT 4向质膜的募集来发挥作用。这一过程的异常是胰岛素抵抗和2型糖尿病的基础。因此，深入了解潜在的信号转导机制将为这些疾病的发病机制和治疗提供重要信息。蛋白激酶D（PKD）是一个新近发现的丝氨酸/苏氨酸激酶家族，参与蛋白质的转运。我们的特点是一种新的异构体PKD，PKDnu，在生化和细胞水平。我们的建议是基于我们的初步发现，PKDnu是由蛋白激酶C（PKC）激活， 一种调节胰岛素刺激的GLUT 4运输的必需酶。此外，我们发现PKDnu直接与囊泡相关膜蛋白2（VAMP 2）相互作用，这是一种关键的GLUT 4囊泡定位蛋白，介导膜融合和GLUT 4运输。因此，我们建议确定PKDnu在胰岛素和佛波酯调节的GLUT 4运输中的作用。我们假设PKDnu在响应胰岛素和佛波酯治疗时，通过其与胰岛素响应细胞中的VAMP 2的相互作用促进含有GLUT 4-VAMP 2的囊泡转运至质膜。这项研究的长期目的是确定PKD如何调节膜运输，并确定治疗蛋白质转运失调疾病的新分子靶点。该研究将为介导胰岛素调节的GLUT 4运输的分子信号机制提供见解。 我们将致力于实现以下具体目标： 目标1.为了验证以下假设：在胰岛素应答细胞中，PKDnu通过PKC依赖性途径被佛波醇酯和胰岛素激活。 目标2.为了检验VAMP 2是胰岛素应答细胞中PKDnu的下游靶标的假设。 目标3.检验PKC/PKDnu/VAMP 2信号通路有助于佛波酯和胰岛素调节的GLUT 4向质膜募集和葡萄糖摄取的假设。

A fundamental role of insulin is to facilitate the uptake of glucose from the blood stream to the insulin-responsive tissues of fat and muscle. In this process, insulin acts mainly by stimulating the recruitment of the facilitative glucose transporter isoform GLUT4 to the plasma membrane. Abnormalities in this process underlie insulin-resistance and type 2 diabetes. Thus, deeper understanding of the underlying signaling mechanisms will provide important information for the pathogenesis and treatment of these diseases. Protein kinase D (PKD) is a newly identified serine/threonine kinase family that has been implicated in protein transport. We have characterized a novel isoform of PKD, PKDnu, at both biochemical and cellular levels. Our proposal is based on our preliminary findings that PKDnu is activated by protein kinase C (PKC), an essential enzyme that regulates insulin-stimulated GLUT4 trafficking. Furthermore, we show that PKDnu directly interacts with the vesicle-associated membrane protein 2 (VAMP2), a critical GLUT4 vesicle-localized protein that mediates membrane fusion and GLUT4 trafficking. Therefore, we propose to determine the role of PKDnu in insulin and phorbol ester regulated GLUT4 trafficking. We hypothesize that PKDnu in response to insulin and phorbol ester treatment, promotes the transport of GLUT4-VAMP2-containing vesicles to the plasma membrane via its interaction with VAMP2 in insulin-responsive cells. The long-term interest of the study is to determine how PKD regulates membrane trafficking and to identify novel molecular targets for the treatment of diseases with deregulated protein transport. The study will provide insights to the molecular signaling mechanisms that mediate insulin-regulated GLUT4 trafficking. We will address the following specific aims: Aim 1. To test the hypothesis that PKDnu is activated by phorbol esters and insulin through a PKC-dependent pathway in insulin-responsive cells. Aim 2. To test the hypothesis that VAMP2 is a downstream target of PKDnu in insulin-responsive cells. Aim 3. To test the hypothesis that the PKC/PKDnu/VAMP2 signaling pathway contributes to phorbol ester and insulin-regulated recruitment of GLUT4 to the plasma membrane and glucose uptake.