Protein kinase Dnu in regulated GLUT4 trafficking

胰岛素的一个基本作用是促进葡萄糖从血液中吸收到脂肪和肌肉中对胰岛素有反应的组织。在这个过程中，胰岛素主要通过刺激促进性葡萄糖转运体亚型GLUT4到质膜上的募集来发挥作用。这一过程中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)是一个新发现的丝氨酸/苏氨酸激酶家族，与蛋白质转运有关。我们在生化和细胞水平上鉴定了一种新的PKD亚型--PKDnu。我们的建议是基于我们的初步发现，即PKDnu由蛋白激酶C(PKC)激活， 调节胰岛素刺激的GLUT4转运的一种重要酶。此外，我们发现PKDnu直接与囊泡相关膜蛋白2(VAMP2)相互作用，VAMP2是一种关键的GLUT4囊泡定位蛋白，介导膜融合和GLUT4转运。因此，我们建议确定PKDnu在胰岛素和佛波酯调节的GLUT4转运中的作用。我们推测，在胰岛素和佛波酯治疗后，PKDnu通过与胰岛素反应细胞中的VAMP2相互作用，促进含有GLUT4-VAMP2的囊泡向质膜的运输。这项研究的长期兴趣是确定PKD如何调节膜运输，并确定新的分子靶点，用于通过解除调节的蛋白质运输来治疗疾病。这项研究将为调节胰岛素调节的GLUT4转运的分子信号机制提供见解。 我们将解决以下具体目标： 目的1.在胰岛素反应细胞中，验证佛波酯和胰岛素通过PKC依赖途径激活PKDnu的假说。 目的2.验证VAMP2是胰岛素反应细胞中PKDnu下游靶点的假设。 目的3.验证PKC/PKDnu/VAMP2信号通路参与佛波酯和胰岛素调节的GLUT4向质膜的募集和葡萄糖摄取的假说。

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.