The role of dendrin in glomerular disease progression

 描述(申请人提供)：确定适当的治疗靶点治疗肾小球疾病的一个关键障碍是对调节足细胞损伤和肾脏存活的信号级联反应的有限了解。我们的长期目标是通过阐明调控足细胞损伤和存活的关键信号通路的细节和功能意义，加强可用于治疗人类肾小球疾病的假定治疗靶点的管道。我们的初步数据已经确定树突蛋白是一个关键的促损伤信号分子，它促进足细胞耗竭，并参与足细胞系膜细胞的串扰。我们已经鉴定出与家族性激素耐药局灶性节段性肾小球硬化(FSGS)分离的人类树突状蛋白基因变异，并发现促进生存的河马途径效应蛋白YAP(YAP)是树突状蛋白功能的抑制因子。本应用的总体目标是确定树突蛋白作为致病足细胞系膜细胞串扰和随后的肾小球疾病进展的关键介质的作用。我们的中心假设是树突蛋白以磷酸化依赖的方式被YAP调节，其中与疾病相关的树突状蛋白突变可能通过降低YAP抑制而诱导足细胞损伤。Dendrin调节的足细胞可溶性因子促进系膜细胞纤维连接蛋白的分泌，导致系膜基质扩张和肾小球疾病进展。这项拟议研究的基本原理是，明确YAP是如何抑制树突状蛋白功能的，并表征其在肾小球疾病进展中的作用，将促进对肾小球疾病进展的了解，以及寻求可用于临床的新的治疗靶点。我们的假设将通过追求两个特定的目标来验证：目标1将探索YAP对野生型和FSGS相关树突变体的抑制作用。我们将定义磷酸化的YAP和树突蛋白亚型之间的分子相互作用，并在细胞存活和树突蛋白亚细胞定位和功能的背景下表征结合的后果。我们还将在体内测试YAP在足细胞中的转基因表达是否通过抑制树突蛋白功能来减缓小鼠肾小球疾病的进展。在目标2中，我们将使用我们建立的新的体外细胞系统以及可诱导的转基因小鼠串扰模型来确定树突状蛋白在致病足细胞系膜细胞串扰中的作用。我们的创新方法利用最先进的蛋白质组学技术从足细胞中识别树突蛋白调节的可溶性因子，诱导系膜细胞纤维连接蛋白的分泌。这些贡献意义重大，因为它们代表了一系列研究的第一步，这些研究有望促进对肾小球疾病进展的了解，并确定治疗目标和策略，以改善临床结果。

 DESCRIPTION (provided by applicant): A critical barrier to the identification of appropriate therapeutic targets to treat glomerular disease is the limited understanding of signaling cascades that regulate podocyte injury and renal survival. Our long term goal is to enhance the pipeline of putative therapeutic targets available to tackle human glomerular disease by elucidating the details and functional significance of key signaling pathways that regulate podocyte injury and survival. Our preliminary data have identified dendrin as a key pro injury signaling molecule that promotes podocyte depletion and is involved in podocyte mesangial cell crosstalk. We have identified human dendrin gene variants that segregate with familial steroid resistant focal segmental glomerulosclerosis (FSGS) and identified the pro survival Hippo pathway effector Yes associated protein (YAP) as an inhibitor of dendrin function. The overall objective of this application is to define the role of dendrin as a key mediator of pathogenic podocyte mesangial cell crosstalk and subsequent glomerular disease progression.Our central hypothesis is that dendrin is regulated in a phosphorylation dependent manner by YAP, where disease associated dendrin mutants may induce podocyte injury though decreased YAP inhibition. Dendrin regulated soluble factors from podocytes promote mesangial cell fibronectin secretion, leading to mesangial matrix expansion and glomerular disease progression. The rationale for the proposed research is that defining how dendrin function is inhibited by YAP and characterizing its role in glomerular disease progression will advance understanding of glomerular disease progression as well as the quest for novel therapeutic targets available for clinical use. Our hypothesis will be tested by pursuing two specific aims: Aim 1 will explore the inhibition of wild type and FSGS associated dendrin mutants by YAP. We will define the molecular interaction between phosphorylated YAP and the dendrin isoforms and characterize the consequences of binding in the context of cell survival and dendrin subcellular localization and function. We will also test in vivo whether transgenic expression of YAP in podocytes slows murine glomerular disease progression by inhibiting dendrin function. In Aim 2 we will define the role of dendrin in pathogenic podocyte mesangial cell crosstalk using our novel established in vitro cell systems as well as an inducible transgenic mouse model of crosstalk. Our innovative approach utilizes state of the art proteomics technology to identify dendrin regulated soluble factors from podocytes that induce mesangial cell fibronectin secretion. These contributions are significant because they represent the first step in a continuum of research that is expected to advance understanding of glomerular disease progression and identify therapeutic targets and strategies to improve clinical outcomes.