GAD AND GABA IN ISLET CELL DEVELOPMENT AND FUNCTION

GAD 和 GABA 在胰岛细胞发育和功能中的作用

• 批准号: 6238986
• 负责人: STEINUNN BAEKKESKOV
• 金额: $ 25.09万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-09-17 至 1998-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6238986
• 关键词: NOD mouse; animal genetic material tag; autoimmunity; cell differentiation; gamma aminobutyrate; gene expression; gene targeting; genetically modified animals; glutamate decarboxylase; immune tolerance /unresponsiveness; immunocytochemistry; insulin dependent diabetes mellitus; intracellular transport; molecular pathology; pancreatic islet function; pancreatic islets; polymerase chain reaction; posttranslational modifications; protein sequence; protein structure function; tissue /cell culture

Pancreatic beta cells and GABA-ergic neurons express the synthesizing enzyme for the inhibitory neurotransmitter GABA, glutamic acid decarboxylase. Pancreatic alpha cells and perhaps also delta cells express GABA/A receptors and GABA may function as a paracrine signaling molecule for communication among the endocrine cells in the pancreas. GAD is encoded by two distinct genes, GAD65 and GAD67, which differ mainly in the first 100 amino acids but share extensive homology in the remainder of the proteins. Human beta cells only express GAD65 and this form of the enzyme is a target of autoantibodies associated with early and late phases of beta cell destruction resulting in type 1 diabetes. Furthermore GAD65 has been shown to be an important T-cell autoantigen in the NOD-mouse model of type 1 diabetes. This project examines the role of GAD65 and GAD67, and GABA in islet cell development, function and beta cell autoantigenicity focusing on the cell biology of the GAD proteins and use of transgenic mouse models of aberrant GAD and GABA expression. The first aim is to characterize the topology of the GAD65 molecule which is synthesized as a hydrophilic soluble molecule, but is post- translationally modified and processed to become anchored to the membrane of synaptic like microvesicles. The second aim is to characterize the signaling and targeting sequences and the modification(s) that confer the subcellular localization of GAD65. The third aim is to characterize transgenic mouse models of over expression of GAD65 in beta cells and the consequences of such expression on islet cell development, function and autoantigenicity. The fourth aim is to generate transgenic mouse models over-expressing GAD65 late in development, and examine the consequences for tolerance development and autoantigenicity. The fifth aim is to characterize the islet cell and neurological function of GAD65 knock out mice and the consequences of rescue by wild type and mutant forms of GAD65. The overall goal is to elucidate the molecular mechanisms of function, subcellular localization and autoantigenicity of the GABA-ergic system in the pancreas.

胰腺β细胞和GABA能神经元表达合成 抑制性神经递质GABA、谷氨酸的酶 脱羧酶 胰腺α细胞和δ细胞 表达GABA/A受体，GABA可能起旁分泌信号作用 胰腺内分泌细胞之间的通讯分子。 GAD由两个不同的基因GAD 65和GAD 67编码，它们不同 主要在前100个氨基酸中，但在前100个氨基酸中具有广泛的同源性。 剩下的蛋白质。 人β细胞仅表达GAD 65， 这种酶的形式是与早期糖尿病相关的自身抗体的靶点。 以及导致1型糖尿病的β细胞破坏的晚期阶段。 此外，GAD 65已被证明是重要的T细胞自身抗原 NOD小鼠1型糖尿病模型中。 本课题研究GAD 65、GAD 67和GABA在胰岛细胞中的作用， 发育、功能和β细胞自身抗原性集中在细胞上 GAD蛋白的生物学和GAD蛋白的转基因小鼠模型的应用 异常GAD和GABA表达。 第一个目的是表征GAD 65分子的拓扑结构， 是作为亲水性可溶性分子合成的，但在 经修饰和加工后固定在膜上 突触状微泡的结构 第二个目的是表征信号和靶向序列 和赋予的亚细胞定位的修饰 GAD65。 第三个目的是表征过度表达的转基因小鼠模型。 β细胞中GAD 65的表达和这种表达的后果 对胰岛细胞发育、功能和自身抗原性的影响。 第四个目标是建立过表达 GAD 65在发展中的后期，并检查耐受性的后果 发育和自身抗原性。 第五个目的是表征胰岛细胞和神经功能 GAD 65敲除小鼠的存活率和野生型和 GAD 65的突变形式。 总体目标是阐明功能的分子机制， GABA能系统的亚细胞定位和自身抗原性 在胰腺中。