Novel Regulators of Islet Beta-Cell Function in Health and Diabetes

健康和糖尿病中胰岛β细胞功能的新型调节剂

• 批准号: 8921631
• 负责人: Anjaneyulu Kowluru
• 金额: --
• 依托单位: JOHN D DINGELL VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8921631
• 关键词: Address; Anabolism; Animal Model; Apoptosis; Apoptotic; Area; Attenuated; Beta Cell; Biochemical; Biological; Biology; C-terminal; Carbon; Cell Survival; Cell membrane; Cell physiology; Cells; Ceramides; Cholesterol; Complement; Coupling; Cysteine; Cytoplasmic Granules; Data; Defect; Development; Diabetes Mellitus; Diet; Docking; Endocrine; Event; Fatty acid glycerol esters; Functional disorder; Funding; GTP-Binding Proteins; Glucose; Goals; Guanine Nucleotide Dissociation Inhibitors; Guanine Nucleotide Exchange Factors; Health; Human; In Vitro; Insulin; Insulin Resistance; Investigation; Laboratories; Lead; Lipids; MAPK11 gene; MAPK8 gene; Mediating; Metabolic; Metabolic stress; Mitochondria; Modification; Molecular; Monomeric GTP-Binding Proteins; Movement; Mus; NADPH Oxidase; Non-Insulin-Dependent Diabetes Mellitus; Nutrient; Obesity; Pancreas; Pathway interactions; Phagocytes; Phosphotransferases; Physiological; Prevention; Preventive Intervention; Protein Isoprenylation; Proteins; Resistance; Rodent; Role; Secretory Vesicles; Seminal; Signal Pathway; Signal Transduction; Signaling Protein; Stimulus; Stress; Testing; Therapeutic Intervention; base; caspase-3; diabetic; endoplasmic reticulum stress; feeding; in vivo; in vivo Model; inhibitor/antagonist; innovation; insight; insulin granule; insulin secretion; islet; mitogen-activated protein kinase p38; mutant; novel; novel therapeutics; prenylation; prevent; protein activation; protein farnesyltransferase; public health relevance; research study; therapeutic development; thermozymocidin; trafficking

 DESCRIPTION (provided by applicant): Original contributions from our laboratory have established novel roles for small G-proteins [e.g., Rac1, Cdc42] in glucose-stimulated insulin secretion [GSIS] from normal rodent and human islets. We provided the first evidence to suggest that these G-proteins undergo post-translational lipidation via incorporation of farnesyl or geranylgeranyl groups at their C-termini. Recent studies from our laboratory have demonstrated novel regulatory roles for protein farnesyltransferase [FTase] and geranylgeranyltransferase [GGTase] in ß-cell function including GSIS. Our efforts have also led to the identification of novel regulatory factors for these G-proteins including GDP-dissociation inhibitors [GDIs] and guanine nucleotide exchange factors [GEFs], which appear to precisely control signaling steps leading to GSIS. During the course of these investigations, we noticed significant defects in FTase/GGTase signaling pathways in in vitro and in vivo models of glucolipotoxicity, endoplasmic reticulum [ER] stress and T2DM. As a logical extension of the previously funded studies, and based on recently accrued exciting preliminary evidence we propose to test the overall hypothesis that glucolipotoxic and ER stress conditions induce defects in the FTase/GGTase signaling cascade leading to sustained activation of small G-proteins [Rac1] and mitochondrial dysregulation and demise of the islet ß-cell. We will accomplish this goal via experiments described under three Specific Aims. In Aim 1, we will determine if glucolipotoxic and ER stress conditions promote alterations in the FTase/GGTase signaling pathway leading to the metabolic dysfunction and apoptosis of the islet ß-cell. In its support, we present preliminary evidence to suggest significant reduction of FTase/GGTase activity and sustained activation of small G-proteins [Rac1] in pancreatic ß-cells under glucolipotoxic conditions. Studies in Aim 2 will delineate the mechanisms underlying sustained activation of G-proteins and accelerated stress kinase signaling steps [JNK1/2, p38 MAP kinase] in the islet ß-cell under conditions of glucolipotoxicity and ER stress. Our preliminary evidence also suggests that inhibitors of Tiam1 [NSC23766] and Vav2 [Ehop-016], two known GEFs for Rac1, significantly attenuated glucotoxic effects in islet ß-cells. Experiments described under Aim 3 will determine if pharmacological intervention and prevention of alterations in FTase/GGTase signaling axis, sustained [constitutive] activation of G-proteins, and abnormalities in downstream metabolic events restore normal ß-cell function in animal models of diet-induced obesity and T2DM. The proposed studies are innovative and carry significant translational impact as they will provide novel insights into the underlying mechanisms for defective FTase/GGTase signaling events leading to islet dysfunction in T2DM, and the data accrued from these studies will form the basis for the identification of novel targets in the FTase/GGTase and G-protein signaling cascades for development of therapeutics to treat T2DM in humans. Our long-standing expertise in the area of G-protein prenylation in islet function including GSIS gives us a unique opportunity to address these important aspects of islet function in health and in diabetes.

 描述（由申请人提供）： 我们实验室的原始贡献已经为小G蛋白建立了新的作用[例如， Rac 1，Cdc 42]在正常啮齿动物和人类胰岛葡萄糖刺激的胰岛素分泌[GSIS]中的作用。我们提供的第一个证据表明，这些G-蛋白通过在其C-末端掺入法尼基或香叶基香叶基进行翻译后脂质化。 我们实验室最近的研究已经证明了蛋白法尼基转移酶[FTase]和香叶基香叶基转移酶[GGT]在包括GSIS在内的胰岛细胞功能中的新的调节作用。我们的努力还导致了这些G蛋白的新的调节因子的鉴定，包括GDP解离抑制剂[GDIs]和鸟嘌呤核苷酸交换因子[GEFs]，它们似乎精确地控制导致GSIS的信号步骤。在这些研究的过程中，我们注意到在体外和体内模型的糖脂毒性，内质网[ER]应激和T2 DM的FTase/GGT酶信号通路的显着缺陷。作为先前资助的研究的逻辑延伸，并且基于最近积累的令人兴奋的初步证据，我们建议测试以下总体假设：糖脂毒性和ER应激条件诱导FTase/GGT酶信号级联中的缺陷，导致小G蛋白[Rac 1]的持续激活和线粒体失调以及胰岛β细胞的死亡。我们将通过三个具体目标下描述的实验来实现这一目标。在目标1中，我们将确定糖脂毒性和ER应激条件是否促进FTase/GGT酶信号通路的改变，导致胰岛β细胞的代谢功能障碍和凋亡。在其支持下，我们提出了初步证据，表明在糖脂毒性条件下，胰腺癌细胞中FTase/GGT酶活性显著降低，小G蛋白[Rac 1]持续活化。目的2中的研究将描述在糖脂毒性和ER应激条件下胰岛β细胞中G蛋白持续活化和应激激酶信号步骤[JNK 1/2，p38 MAP激酶]加速的潜在机制。我们的初步证据还表明，Tiam 1 [NSC 23766]和Vav 2 [Ehop-016]（Rac 1的两种已知GEF）的抑制剂显著减弱了胰岛β细胞中的葡萄糖毒性作用。目标3下描述的实验将确定药物干预和预防FTase/GGT酶信号传导轴的改变、G蛋白的持续[组成性]激活和下游代谢事件的异常是否恢复饮食诱导的肥胖和T2 DM动物模型中正常的胰岛细胞功能。拟议的研究具有创新性，并具有重大的转化影响，因为它们将为T2 DM中导致胰岛功能障碍的缺陷性FTase/GGT酶信号传导事件的潜在机制提供新的见解，并且从这些研究中获得的数据将形成识别新靶点的基础 在FTase/GGT酶和G蛋白信号级联中用于开发治疗人类T2 DM的疗法。我们在包括GSIS在内的胰岛功能中G蛋白异戊二烯化领域的长期专业知识为我们提供了一个独特的机会来解决健康和糖尿病中胰岛功能的这些重要方面。