Protein Kinase C (PKC) Zeta and the Pancreatic Beta Cell

描述(申请人提供)：糖尿病是由于缺乏功能性的β细胞所致。旨在分析关键生长因子/激素和细胞内信号分子如何促进β细胞增殖、防止β细胞丢失和促进胰岛素释放的研究，对于未来的糖尿病治疗方法至关重要。在这项研究中，我们关注的是磷脂酰肌醇3‘-激酶的一个重要下游靶点--非典型蛋白激酶C(PKC)信号通路。这一途径的激活增强了多种细胞类型的增殖、功能和存活。重要的是，在β细胞中，我们已经证明了生长因子和葡萄糖等营养物质激活了非典型亚型PKC Zeta(？)。然而，该信号通路在β细胞中的作用仍处于早期阶段。是PKC吗？在体外和体内葡萄糖介导的β细胞增殖和功能中起关键作用？我们的初步结果表明，葡萄糖确实需要PKC？促进小鼠和人的β细胞体外增殖。此外，PKC？在体外，小鼠和人的胰岛中的β细胞的增殖和胰岛素的分泌增加。它在体内也会发生吗？在目前的方案中，使用一种新的四天葡萄糖输注模型和表达显性阴性或结构性活性PKC的转基因小鼠？在β细胞中的异构体，我们将充分表征PKC？胰岛移植环境中基础和葡萄糖介导的β细胞生长和功能及其治疗潜力。为了发展这个项目，我们将实现以下具体目标：1.界定PKC的角色？体内葡萄糖介导的β细胞增殖。2.评价PKC结构性激活的作用。在体外和体内对β细胞的增殖、功能和存活的影响。3.评价PKC结构性激活的疗效。在SCID小鼠胰岛移植的边缘质量模型中改善小鼠和人类胰岛移植的结果。我们的初步结果证明了PKC的核心和关键作用。β细胞生长和功能的信号转导。因此，拟议的研究将提供关于PKC影响的宝贵信息？关于β细胞的增殖、功能、存活和胰岛移植。如果翻译成人类，PKC的结构性激活？可能是一种有吸引力的治疗策略，可以扩大糖尿病患者的β细胞质量和功能。公共卫生相关性：我们已经证明，生长因子和营养物质，如葡萄糖，可以激活非典型的PKC Zeta(？)在贝塔细胞中。激活PKC？结果增加了小鼠，最重要的是，在体外人类β细胞的增殖。目前提案中的研究将破译：(I)PKC的影响？体内的β细胞；(Ii)PKC的潜在机制？对β细胞的影响；以及(Iii)其在胰岛移植环境中的治疗潜力。拟议的研究将提供关于PKC影响的宝贵信息？关于β细胞的增殖、功能、存活和胰岛移植。如果翻译成人类，PKC的激活？可能是一种有吸引力的治疗策略，可以扩大糖尿病患者的β细胞质量和功能。

DESCRIPTION (provided by applicant): Diabetes results from a deficiency of functional beta cells. Studies aimed at analyzing how key growth factors/hormones and intracellular signaling molecules can increase beta cell proliferation, prevent beta cell loss and enhance insulin release are essential for future therapeutic approaches for diabetes. In this proposal, we focus on one of the important downstream targets of phosphatidylinositol 3'-kinase, the atypical protein kinase C (PKC) signaling pathway. Activation of this pathway enhances proliferation, function and survival in numerous cell types. Importantly, in the beta cell, we have shown that growth factors and nutrients such as glucose activate the atypical isoform PKC zeta (?). However, the role of this signaling pathway in the beta cell is still in its early infancy. Is PKC ? crucial in glucose-mediated beta cell proliferation and function in vitro and in vivo? Our preliminary results indicate that glucose indeed requires PKC ? to increase mouse and human beta cell proliferation in vitro. Furthermore, constitutive activation of PKC ? in beta cells results in increased mouse and human beta cell proliferation and insulin secretion in vitro in mouse islets. Does it occur in vivo as well? In the current proposal, using a novel four-day glucose infusion model and transgenic mice expressing dominant-negative or constitutively active PKC ? isoforms in the beta cell, we will fully characterize the role of PKC ? on basal and glucose-mediated beta cell growth and function and its therapeutic potential in an islet transplant setting. To develop this project, we will implement the following Specific Aims: 1. To define the role of PKC ? in glucose-mediated beta cell proliferation in vivo. 2. To assess the effect of constitutive activation of PKC ? in beta cell proliferation, function and survival in vitro and in vivo. 3. To evaluate the efficacy of constitutive activation of PKC ? in improving mouse and human islet transplant outcomes in a marginal mass model of islet transplantation in SCID mice. Our preliminary results demonstrate a central and critical role for PKC ? signaling in beta cell growth and function. Thus, the proposed studies will provide invaluable information on the impact of PKC ? on beta cell proliferation, function, survival and islet transplantation. If translated into humans, constitutive activation of PKC ? may be an attractive therapeutic strategy for expanding beta cell mass and function in patients with diabetes. PUBLIC HEALTH RELEVANCE: We have shown that growth factors and nutrients such as glucose activate atypical PKC zeta (?) in beta cells. Activation of PKC ? results in increased mouse and, most importantly, human beta cell proliferation in vitro. Studies in the current proposal will decipher: (i) the effects of PKC ? in the beta cell in vivo; (ii) the mechanisms underlying PKC ? effects in the beta cell; and, (iii) its therapeutic potential in an islet transplant setting. The proposed studies will provide invaluable information on the impact of PKC ? on beta cell proliferation, function, survival and islet transplantation. If translated into humans, activation of PKC ? may be an attractive therapeutic strategy for expanding beta cell mass and function in patients with diabetes.