The Role of Endocytosis and Actin Regulation in Podocytes

描述（由申请人提供）：慢性肾脏疾病（CKD）经常导致肾功能不可逆转的恶化，并经常发展为终末期肾脏疾病（ESKD）。CKD已经成为一个严重的公共卫生问题，从USRDS获得的数据显示，到2015年，美国ESKD的新病例数预计将超过70万例。由于继发于足细胞功能障碍的肾小球疾病占所有ESKD的80%，一种详细的分子和遗传学方法来确定足细胞发育和修复的机制可能为我们开发治疗药物提供新的靶点。最近的细胞培养模型描述了足细胞内吞作用的可能作用。为了进一步确定其重要性，我们确定了调节内吞作用、synaptojanin 1和dynamin的重要基因，这些基因在小鼠中缺失会导致严重的蛋白尿和足突消失。我们还通过蛋白质组学筛选发现了嗜内啡肽，一种突触蛋白1和动力蛋白的相互作用物，嗜内啡肽的缺失也会导致严重的蛋白尿。有趣的是，其他蛋白质如CD2AP和Myo1e是动力蛋白和突触蛋白1的相互作用物，通过人类遗传研究，它们是足突完整性的核心。在目标1中，我们将定义内吞调节缺失如何导致足细胞功能障碍的基本机制。在Aim 2中，我们将描述嗜内蛋白在肾小球生物学中的作用，并研究足细胞内吞作用和肌动蛋白之间的联系。最后，在Aim 3中，我们将采用小鼠肾小球损伤模型来确定损伤后内吞作用的影响。我们的研究结果强烈暗示了在肾小球滤过屏障形成和维持过程中控制网格蛋白介导的内吞作用的蛋白质网络。通过完成这些目标，我们将有机会进一步扩展我们对足细胞稳态至关重要的内吞途径的知识。

DESCRIPTION (provided by applicant): Chronic kidney disease (CKD) often leads to irreversible deterioration of renal function that often progresses to End Stage Kidney Disease (ESKD). CKD has emerged as a serious public health issue and data obtained from the USRDS reveals that the number of new cases of ESKD in the United States is projected to exceed 700,00 patients by year 2015. As glomerular diseases secondary to podocyte dysfunction contribute up to 80% of all ESKD, a detailed molecular and genetic approach to identify mechanisms for podocyte development and repair may give us new targets for developing therapeutic agents. Recent cell culture models have described the possible role of endocytosis in podocytes. To further determine its importance, we identified important genes regulating endocytosis, synaptojanin 1, and dynamin, which when deleted in mice results in severe proteinuria and foot process effacement. We also identified endophilin, an interactor of synaptojanin 1 and dynamin through a proteomic screen, and loss of endophilin also results in severe proteinuria. Interestingly, other proteins such as CD2AP and Myo1e, which are central to the integrity of foot processes via genetic studies in humans are dynamin and synaptojanin 1 interactors. In Aim 1, we will define the fundamental mechanisms on how loss of endocytic regulation contributes to podocyte dysfunction. In Aim 2, we will characterize the role of endophilin in glomerular biology, and investigate the link between endocytosis and actin in podocytes. Lastly, in Aim 3, we will incorporate mice glomerular injury models to identify the impact of endocytosis after injury. Our results strongly implicate a protein network that controls clathrin-mediated endocytosis in the formation and maintenance of the glomerular filtration barrier. By completing these aims, we will have an opportunity to further expand our knowledge of endocytic pathways vital for podocyte homeostasis.