IDENTIFICATION AND CHARACTERIZATION OF THE GLEPP1/RECEPTOR LIGAND

GLEPP1/受体配体的鉴定和表征

• 批准号: 6338751
• 负责人: ROGER Charles WIGGINS
• 金额: $ 14.5万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-08-01 至 2001-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6338751
• 关键词: cell line; chimeric proteins; crosslink; expression cloning; genetic library; glomerular filtration; guinea pigs; immunoelectron microscopy; in situ hybridization; intercellular connection; laboratory rabbit; laboratory rat; ligands; membrane proteins; molecular cloning; molecular pathology; nephrotic syndrome; posttranslational modifications; protein binding; protein sequence; protein tyrosine phosphatase; proteinuria; renal glomerulus; transfection; western blottings

Progression to ESRD of diabetic glomerulosclerosis and other sclerosing glomerular diseases (e.g. FSGS) is associated with a leak of protein through the glomerular filter (the Nephrotic Syndrome). A major cell responsible for maintaining the integrity of the glomerular filter is the podocyte, whose interdigitating foot processes about the glomerular basement membrane, and between which the glomerular filtrate is formed. With prior support from the Renal Center we have identified, cloned and sequenced two major proteins of importance for the function of the glomerular filter. These are a novel podocyte foot process receptor tyrosine phosphatase (called GLEPP1) and podocalyxin (the major negatively charged molecule of the foot process originally identified by Farquhar and colleagues which is responsible for keeping foot processes apart by charge repulsion). Recent analysis of the GLEPP1 receptor shows that antibodies to the GLEPP1 receptor-like PTPase cause the glomerulus to become more permeable to albumin (leaky), probably in part by inhibiting the PTPase function of the enzyme. Thus a direct and previous unknown mechanism of control of the glomerular filter has been identified. At the same time new information shows that in other cells PTPases regulate intercellular junctions that are analogous to the slit diaphragms (specialized intercellular junctions) that serve as filtration devices between the foot processes of the podocyte. In this application we propose (a) to identify the GLEPP1 ligand using a recombinant GLEPP1 extracellular domain construct and a mammalian cDNA expression cloning strategy, and (b) to test the hypothesis that interference with the GLEPP1-ligand interaction modulates glomerular filter permeability using an isolated glomerular permeability assay. The long term goal will be to develop pharmacologic agents which can modulate glomerular permeability through this mechanism.

糖尿病肾小球硬化症和其他硬化症进展为 ESRD 肾小球疾病（例如 FSGS）与蛋白质泄漏有关 通过肾小球滤过器（肾病综合症）。一个主要细胞 负责维持肾小球滤过器完整性的是 足细胞，其指状足突围绕肾小球 基底膜，其间形成肾小球滤液。 在肾脏中心的事先支持下，我们已经鉴定、克隆和 对两种对功能具有重要意义的主要蛋白质进行了测序 肾小球滤过器。这些是一种新型足细胞足突受体 酪氨酸磷酸酶（称为 GLEPP1）和足萼蛋白（主要的负面影响） 最初由 Farquhar 发现的足突带电分子和 负责通过电荷保持足突分开的同事 排斥力）。最近对 GLEPP1 受体的分析表明，抗体 GLEPP1 受体样 PTPase 导致肾小球变得更加 可渗透白蛋白（渗漏），可能部分是通过抑制 PTPase 酶的功能。因此，一种直接且先前未知的机制 肾小球滤过器的控制已被确定。同时新 信息表明，在其他细胞中，PTPases 调节细胞间质 类似于狭缝隔膜的结点（专门 细胞间连接）作为足部之间的过滤装置 足细胞的过程。在此应用中，我们建议 (a) 确定 使用重组 GLEPP1 胞外域的 GLEPP1 配体 构建哺乳动物 cDNA 表达克隆策略，以及 (b) 检验干扰 GLEPP1-配体相互作用的假设 使用分离的肾小球调节肾小球滤过器的渗透性 渗透性测定。长期目标是开发药理学 可以通过这种机制调节肾小球通透性的药物。