Glomerular Disease Mechanisms mediated by Podocyte TRPC6

足细胞 TRPC6 介导的肾小球疾病机制

• 批准号: 8529507
• 负责人: Jochen Reiser
• 金额: $ 30.34万
• 依托单位: RUSH UNIVERSITY MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-10 至 2015-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8529507
• 关键词: Actins; Address; Affect; Applications Grants; Binding; Biochemical; Biological Preservation; Calcineurin; Calcineurin Pathway; Cathepsin L; Cell membrane; Cyclic AMP-Dependent Protein Kinases; Cytoskeleton; Data; Development; Disease; Dominant-Negative Mutation; Elements; Enzymes; F-Actin; Feedback; Focal Segmental Glomerulosclerosis; Foot Process; Forskolin; Genes; Goals; Human; Hyperactive behavior; Inherited; Injury; Ion Channel; Kidney; Kidney Diseases; Kidney Failure; Knock-out; Lead; Lesion; Mediating; Membrane; Modeling; Molecular Biology; Mus; Mutate; Mutation; Nephrotic Syndrome; Pathway interactions; Patients; Permeability; Pharmaceutical Preparations; Phenotype; Phosphorylation; Physiological; Play; Protein Dephosphorylation; Proteins; Proteinuria; Regulation; Renal glomerular disease; Resistance; Rodent; Role; Signal Transduction; Small Interfering RNA; System; Testing; Work; calcineurin phosphatase; calmodulin-dependent protein kinase II; gain of function mutation; in vivo; mutant; novel; overexpression; podocyte; public health relevance; response; slit diaphragm; synaptopodin

DESCRIPTION (provided by applicant): This project aims to delineate disease causing mechanisms of dysfunctional ion channel TRPC6 in podocytes. TRPC6 is part of the slit diaphragm relating Ca2+ signals into podocyte foot processes and mutated TRPC6 or induced expression of wild type TRPC6 protein can cause hereditary and acquired proteinuric diseases, respectively. Thus, (dys-) regulation of TRPC6 likely affects millions of patients with glomerular disease. We have generated novel preliminary data demonstrating a unique functional interaction between TRPC6 and synaptopodin producing a regulatory loop, that coordinates physiological podocyte function but triggers podocyte injury in the case of dysregulated TRPC6 mediated Ca2+ signals. We propose to test our central hypothesis that TRPC6 and synaptopodin cooperate in the regulation of the dynamic podocyte actin cytoskeleton. While synaptopodin binds to TRPC6 and regulates its membrane expression, TRPC6 mediated Ca2+ influx determines the stability of synaptopodin through Ca2+ sensitive enzymes calcineurin and protein kinase A (PKA). According to our novel data, increased TRPC6 channel activity disrupts normal podocyte actin cytoskeletal dynamics via the activation of calcineurin that in turn leads to the degradation of synaptopodin thereby causing proteinuric kidney disease. In addition, diminished TRPC6 mediated Ca2+ influx into podocytes leads to reduced activity of PKA and thus reduced protective synaptopodin phosphorylation with its subsequent degradation. Normal Ca2+ transport of TRPC6 maintains physiological synaptopodin levels that allow a dynamic regulation of the podocyte foot process system and kidney barrier. Specific Aim 1 will address how TRPC6 regulates synaptopodin-mediated actin cytoskeletal dynamics. Specific Aim 2 seeks to define how synaptopodin affects TRPC6 channel activity and localization. In Specific Aim 3, we will study the consequences of TRPC6 deficiency and TRPC6 hyperactivity on podocyte actin cytoskeletal dynamics and glomerular barrier function in vivo. Our work will clarify an important downstream mechanism that permits podocyte injury originating from dysregulated TRPC6. Our findings may have broad implications for the understanding of the pathobiology of TRPC6-related human kidney diseases including Focal Segmental Glomerulosclerosis (FSGS) and promote the development of anti-proteinuric drugs interfering with TRPC6 and its cellular effects on podocytes. PUBLIC HEALTH RELEVANCE: The broad, long-term goal of this grant proposal is to advance our understanding of podocyte biology and the molecular mechanisms leading to proteinuria and nephrotic syndrome that originate from podocyte injury. If our hypothesis is correct, our work may have broad implications for the understanding of the pathobiology of TRPC6-related human kidney diseases including Focal Segmental Glomerulosclerosis (FSGS) and promote the development of anti-proteinuric drugs interfering with TRPC6 channel function.

描述（由申请人提供）：该项目旨在描述足细胞中功能失调的离子通道 TRPC6 的致病机制。 TRPC6 是将 Ca2+ 信号关联到足细胞足突的裂隙隔膜的一部分，突变的 TRPC6 或野生型 TRPC6 蛋白的诱导表达可分别导致遗传性和获得性蛋白尿疾病。因此，TRPC6 的（失调）调节可能会影响数百万肾小球疾病患者。我们已经生成了新的初步数据，证明 TRPC6 和突触蛋白之间产生调节环路的独特功能相互作用，该调节环路协调生理足细胞功能，但在 TRPC6 介导的 Ca2+ 信号失调的情况下触发足细胞损伤。我们建议测试我们的中心假设，即 TRPC6 和突触蛋白在动态足细胞肌动蛋白细胞骨架的调节中合作。虽然突触足蛋白与 TRPC6 结合并调节其膜表达，但 TRPC6 介导的 Ca2+ 内流通过 Ca2+ 敏感酶钙调神经磷酸酶和蛋白激酶 A (PKA) 决定了突触足蛋白的稳定性。根据我们的新数据，TRPC6 通道活性增加通过激活钙调神经磷酸酶破坏正常足细胞肌动蛋白细胞骨架动力学，进而导致突触足蛋白降解，从而引起蛋白尿肾病。此外，TRPC6 介导的 Ca2+ 流入足细胞的减少导致 PKA 活性降低，从而减少保护性突触蛋白磷酸化及其随后的降解。 TRPC6 的正常 Ca2+ 转运维持生理突触蛋白水平，从而动态调节足细胞足突系统和肾屏障。具体目标 1 将解决 TRPC6 如何调节突触蛋白介导的肌动蛋白细胞骨架动力学。具体目标 2 旨在定义突触蛋白如何影响 TRPC6 通道活动和定位。在具体目标 3 中，我们将研究 TRPC6 缺乏和 TRPC6 过度活跃对体内足细胞肌动蛋白细胞骨架动力学和肾小球屏障功能的影响。我们的工作将阐明一个重要的下游机制，该机制允许源自失调的 TRPC6 的足细胞损伤。我们的研究结果可能对理解 TRPC6 相关人类肾脏疾病（包括局灶节段性肾小球硬化症 (FSGS)）的病理学具有广泛的意义，并促进干扰 TRPC6 及其对足细胞的细胞效应的抗蛋白尿药物的开发。 公共健康相关性：这项拨款提案的广泛、长期目标是增进我们对足细胞生物学以及足细胞损伤导致蛋白尿和肾病综合征的分子机制的理解。如果我们的假设正确，我们的工作可能对理解 TRPC6 相关人类肾脏疾病（包括局灶节段性肾小球硬化症 (FSGS)）的病理学产生广泛的影响，并促进干扰 TRPC6 通道功能的抗蛋白尿药物的开发。