Role of dynamin oligomerization in podocyte structure and function

 描述（由申请人提供）：慢性肾脏疾病的全球流行正在以惊人的速度发展。仅在美国，肾小球肾病就影响了大约2000万人，并且这个数字在过去二十年中大约翻了一番。事实上，与肾脏有关的疾病正在迅速地远离目前的治疗选择和资源。因此，发现治疗慢性肾脏疾病的新疗法是高度优先的。足细胞是肾小球内的特化细胞，对肾脏超滤至关重要。它们形成fot过程（FP），高度动态的肌动蛋白为基础的细胞延伸，由狭缝隔膜连接。大多数形式的蛋白尿和肾病综合征的特征在于由于肌动蛋白细胞骨架的失调（称为FP消失），足细胞FP转化为细胞质条带。这项建议的工作是基于我们最近鉴定的GTdR动力蛋白作为足细胞肌动蛋白动力学的主要调节因子。该实验室的研究表明，动力蛋白功能的保留足以逆转FP消失，恢复功能性足细胞，并改善蛋白尿。我们已经表明，发动蛋白直接调节足细胞中的肌动蛋白细胞骨架。此外，我们已经确定了小分子，促进发动蛋白寡聚成环，这反过来又保护了足细胞中的肌动蛋白细胞骨架。我们最近发现，在各种慢性肾脏疾病动物模型中，动力蛋白特异性小分子的给药逆转了FP消失并改善了蛋白尿。最初，我们专注于动力蛋白在调节足细胞肌动蛋白细胞骨架中的作用。在这个补助金申请中，我们扩大了我们原来的观察重点的作用，动力肌动蛋白的相互作用，动力寡聚化，和动力特异性分子发挥调节网格蛋白介导的内吞作用。内吞作用是所有真核生物中的一个关键过程，通过该过程，质膜的部分沿着胞外物质被内化。它在调节起源于质膜的信号通路中起重要作用。在具体目标1中，我们研究了发动蛋白在调节足细胞肌动蛋白依赖性内吞作用中的作用。在特定目标2中，我们研究了内吞作用是否在足细胞和肾小球内皮细胞之间的串扰中起作用。在特定目标3中，我们通过研究动力蛋白特异性小分子在进行性肾损伤啮齿动物模型中的作用，研究肌动蛋白依赖性内吞作用是否在逆转肾小球损伤的早期体征（如系膜基质扩张和IV型胶原沉积）中起作用。

 DESCRIPTION (provided by applicant): The global epidemic of chronic kidney disease is progressing at an alarming rate. In the United States alone, glomerular kidney diseases affect some 20 million people, and this number has roughly doubled in the last two decades. Indeed, kidney-related diseases are rapidly eluding present treatment options and resources. Thus, it is a high priority to uncover novel therapeutics to treat chronic kidney diseases. Podocytes are specialized cells within the glomerulus that are essential for kidney ultrafiltration. They form fot processes (FPs), highly dynamic actin-based cellular extensions that are connected by slit diaphragms. Most forms of proteinuria and nephrotic syndromes are characterized by the transformation of podocyte FPs into bands of cytoplasm due to dysregulation of the actin cytoskeleton (referred to as FP effacement). The work in this proposal is based on our recent identification of the GTPase dynamin as a major regulator of actin dynamics in podocytes. Studies from this laboratory suggest that preservation of dynamin function is sufficient to reverse FP effacement, restore functional podocytes, and ameliorate proteinuria. We have shown that dynamin directly regulates the actin cytoskeleton in podocytes. In addition, we have identified small molecule that promotes dynamin oligomerization into rings, which in turn protects the actin cytoskeleton in podocytes. We have recently shown that administration of dynamin-specific small molecule reversed FP effacement and ameliorated proteinuria in diverse animal models of chronic kidney diseases. Originally, we focused on the role of dynamin in regulating the actin cytoskeleton in podocytes. In this grant application we expand our original observation by focusing on the role that dynamin-actin interaction, dynamin oligomerization, and dynamin-specific molecules play in regulating clathrin-mediated endocytosis. Endocytosis is a key process in all eukaryotes by which portions of the plasma membrane, along with extracellular material, are internalized. It plays an essential role in regulating signaling pathwas that originate at the plasma membrane. In Specific Aim 1 we investigate the role that dynamin plays in regulating actin-dependent endocytosis in podocytes. In Specific Aim 2 we investigate whether endocytosis plays a role during crosstalk between podocytes and glomerular endothelial cells. In Specific Aim 3 we investigate whether actin-dependent endocytosis plays a role in reversing early signs of glomerular injury such as mesangial matrix expansion and deposition of collagen IV by examining the effects of dynamin-specific small molecules in rodent models of progressive kidney injury.