Regulation of Podocyte Actin Cytoskeleton

描述(由申请人提供)： 终末期肾病(ESRD)是一个重要的公共卫生问题。根据USRDS 2005年的数据，ESRD患者使用了19.2%的医疗保险支出(213亿美元)。糖尿病肾病和肾小球肾炎约占透析患者的56.5%。肾小球是肾脏的过滤单位。足细胞是形态独特的细胞，具有章鱼样的突起(足突)，这些突起交错形成裂开的横隔膜。大多数肾小球疾病表现为蛋白尿和足细胞足突消失。我们的实验室已经确定了缝隙横隔膜蛋白用来调节足细胞肌动蛋白细胞骨架的信号机制。这些信号机制似乎对维持该细胞的独特结构和功能至关重要。其中几种基因产物的人类突变，如Neph in、Podocin和α-Actinin-4，会导致足突消失和蛋白尿，并导致肾脏瘢痕形成，导致肾功能衰竭，最终导致需要透析的终末期肾脏疾病。这一应用的指导性假设是缝隙横隔膜蛋白复合体调节足细胞肌动蛋白细胞骨架动力学。在前期工作的基础上，本项目将重点研究这一机制的几个方面。具体地说，我们将：(1)研究NePhin和Neph1在肌动蛋白聚合中协同作用的信号机制。我们的初步数据表明，nWASP和Cortactin在NePhin/Neph1介导的肌动蛋白聚合中发挥了作用。已知这些蛋白质可以组装、促进、调节和稳定肌动蛋白聚合复合体。利用生化和细胞生物学技术，我们将表征这两种蛋白质与Nephin和Neph1的相互作用。(2)探讨cofilin在足细胞肌动蛋白细胞骨架动力学中的作用。我们的初步数据显示了Nephin和Cofilin之间的信号关系。粘附素是肌动蛋白聚合和重塑所必需的。3.为了进一步研究足细胞中cofilin在发育和损伤中的生理作用，我们将以足细胞特有的方式对小鼠进行基因工程和表型鉴定。

DESCRIPTION (provided by applicant): End stage renal disease (ESRD) is an important public health issue. Based on 2005 USRDS data ESRD patients utilize 19.2 percent of medicare spending (21.3 billion dollars). Diabetic nephropathy and glomerulonephritis contributes about 56.5 percent of the incident patients on dialysis. Glomerulus is the filtering unit of the kidney. Podocytes are morphologically unique cells, which have octopus-like processes (foot processes) which interdigitate to form the slit diaphragm. Most glomerular diseases present with proteinuria and podocyte foot process effacement. Our lab has identified signaling mechanisms employed by slit diaphragm proteins to regulate the actin cytoskeleton of the podocyte. These signaling mechanisms appear to be essential for maintaining the unique structure and function of this cell. Human mutations of several of these gene products such as Nephrin, Podocin, and alpha actinin-4 lead to foot process effacement and proteinuria and result in scarring of the kidney causing renal failure and eventually end stage renal disease requiring dialysis. The guiding hypothesis of this application is that the slit diaphragm protein complex regulates podocyte actin cytoskeletal dynamics. Based on our preliminary work, this project will focus on several aspects of this mechanism. Specifically we will: (1) Investigate signaling mechanisms by which Nephrin and Neph1 cooperate in actin polymerization. Our preliminary data suggests a role for nWASP and cortactin in Nephrin/Neph1 mediated actin polymerization. These proteins are known to assemble, promote, regulate and stabilize the actin polymerization complex. Using biochemical and cell biological techniques we will characterize the interaction of these two proteins with Nephrin and Neph1. (2) Investigate the role of cofilin in podocyte actin cytoskeletal dynamics. Our preliminary data shows a signaling relationship between Nephrin and cofilin. Cofilin is necessary for actin polymerization and remodeling. 3. To further characterize the physiological role of cofilin in podocytes in development and in podocyte injury, we will engineer and phenotye mice deleted of cofilin in a podocyte-specific fashion.