mTOR signaling and regulation of alpha-cell mass and function

糖尿病是影响人类健康的最常见疾病之一，21世纪退伍军人也不例外 世纪。我们努力了解这种疾病的发病机制和治疗方法的大部分重点是 重点关注两个主要组成部分：胰岛素敏感性和胰岛素分泌。然而，胰高血糖素的失调 分泌物是糖尿病的主要成分。高血糖在糖尿病的发病机制中起关键作用 2型糖尿病中的高血糖，并在血糖波动和易感性方面有重要影响 1型糖尿病患者的低血糖。我们在当前资金期发表的观察结果表明， 在胰岛素/Akt下游，营养敏感通路(mTOR/Raptor或mTORC1)在 α细胞质量和胰升糖素分泌的调节。然而，mTORC1如何作用于关键下游 靶点(4E-BPS和S6K)调节体内α细胞的功能和质量及其可能的贡献 其中调控糖代谢的靶点尚不清楚。这些研究的长期目标是 揭示营养敏感的胰岛素/Akt/mTORC1轴如何调节α细胞质量和胰升糖素的分泌 在啮齿动物模型和人类身上。我们的研究表明，阿尔法细胞mTORC1功能的丧失会导致 阿尔法细胞团和胰高血糖素分泌的主要异常。我们还证明了mTORC1的增益 结果导致慢性高血糖素血症和阿尔法细胞团扩张，表明这一信号通路是 对阿尔法细胞团和胰升糖素的分泌至关重要。基于这些观察，我们假设 MTORC1主要通过S6K和4E-BP信号之间的平衡来调节α细胞质量。具体目标 将通过建立以下角色来评估mTORC1下游目标的单独贡献 MTORC1/4E-BP/eIF4E轴在α细胞质量、胰高血糖素分泌和适应中的作用 使用新的阿尔法细胞特异性模型的糖尿病发生条件。此外，我们还将确定 MTORC1/S6K通过产生新的模型控制α细胞质量和胰升糖素分泌 阿尔法细胞中S6K函数的感应增益。最后，mTORC1激活如何改变人类阿尔法细胞 将使用人胰岛移植模型在前房确定反应。 老鼠眼。这一提议将对控制阿尔法细胞的分子机制提供重要的见解。 质量膨胀由mTORC1.此信息可用于发现可用于 糖尿病的治疗和设计干预措施以挽救胰高血糖素分泌缺陷 糖尿病患者的低血糖。

Diabetes mellitus is one of the most prevalent conditions affecting human health including veterans in the 21st century. Most of the focus of our efforts to understand the pathogenesis and therapy of the disease has focused on two major components: insulin sensitivity and insulin secretion. However, dysregulation in glucagon secretion is a major component in diabetes. Hyperglucagonemia plays key roles in the pathogenesis of hyperglycemia in type 2 diabetes and has a major impact in the glycemic volatility and susceptibility to hypoglycemia in type 1 diabetes. Our observations published during the current funding period suggest that downstream of insulin/Akt, the nutrient sensitive pathway (mTOR/Raptor or mTORC1) plays a major role in regulation of alpha cell mass and glucagon secretion. However, how mTORC1 acting on key downstream targets (4E-BPs and S6K) regulates the function and mass of alpha-cells in vivo and the potential contribution of these targets to the regulation of glucose metabolism remain unclear. The long-term goal of these studies is to uncover how the nutrient sensitive insulin/Akt/mTORC1 axis regulates α-cell mass and glucagon secretion in rodent models and humans. Our studies showed that loss of mTORC1 function in alpha-cells results in major abnormalities in alpha-cell mass and glucagon secretion. We also demonstrate that gain of mTORC1 results in chronic hyperglucagonemia and alpha cell mass expansion suggesting that this signaling pathway is critical for alpha cell mass and glucagon secretion. Based on these observations, we hypothesize that mTORC1 regulates alpha-cell mass mainly by a balance between S6K and 4E-BP signaling. The specific aims will assess the individual contribution of downstream targets of mTORC1 by establishing the role of mTORC1/4E-BP/eIF4E axis in regulation of alpha-cell mass, glucagon secretion and adaptation to diabetogenic conditions using novel alpha cell specific models. In addition, we will also identify the importance of mTORC1/S6K on the control of alpha-cell mass and glucagon secretion by generation of novel models with inducible gain of S6K function in alpha cells. Finally, how mTORC1 activation alters human alpha-cell responses will be determined using a model of human islet transplantation in the anterior chamber of the mouse eye. This proposal will provide important insights into the molecular mechanisms that govern alpha-cell mass expansion by mTORC1. This information can be used to uncover novel targets that can be used for treatment of diabetes and design interventions to rescue the defects in glucagon secretion in response to hypoglycemia in patients with diabetes.