Use of small molecules that stabilize dynamin rings in podocytopathies

描述（由申请人提供）：慢性肾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增加了一倍。事实上，与肾脏相关的疾病正在迅速摆脱现有的治疗选择和资源。因此，发现治疗慢性肾脏疾病的新疗法是当务之急。足细胞是肾小球内的特殊细胞，对于肾脏超滤至关重要。它们形成足突（FP），这是一种基于肌动蛋白的高度动态的细胞延伸，通过狭缝隔膜连接。大多数形式的蛋白尿和肾病综合征的特征是由于肌动蛋白细胞骨架的失调（称为FP消失），足细胞FP转变为细胞质带。本提案中的工作基于我们最近确定的 GTP 酶动力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，保留动力功能足以逆转 FP 消失、恢复功能性足细胞和改善蛋白尿。我们最近发现动力蛋白直接调节足细胞中的肌动蛋白细胞骨架。此外，我们还发现了促进动力蛋白寡聚成环的小分子，这反过来又保护足细胞中的肌动蛋白细胞骨架。在这项拨款申请中，我们测试了动力环稳定剂药物在不同的蛋白尿肾病啮齿动物模型中逆转 FP 消失和改善蛋白尿的能力。在具体目标 1 中，我们测试了动力药物在蛋白尿肾病诱导模型中的功效，例如嘌呤霉素氨基核苷 (PAN) 肾病大鼠模型和阿霉素肾病大鼠模型。在具体目标 2 中，我们测试了动力环稳定剂药物在蛋白尿肾病遗传模型中的功效，例如（1）小鼠模型，其中肌动蛋白细胞骨架由于“功能获得”1-肌动蛋白 4 突变体的表达而被错误调节； (2) 缺乏CD2AP（参与调节肌动蛋白细胞骨架和足细胞信号转导的适配器蛋白）的小鼠； (3)表达高水平TGF-¿1的转基因小鼠。在具体目标 3 中，我们检查环稳定药物是否影响质膜上去氧肾上腺素的周转。我们的工作有可能将动力药物确定为治疗蛋白尿性肾病的新疗法。 公共卫生相关性：仅在美国，肾小球型肾脏疾病就影响了大约 2000 万人，并且这个数字在过去二十年中大约增加了一倍。在这里，我们建议测试专门针对 GTP 酶动力的小分子（药物）子集通过恢复足细胞结构和功能来改善蛋白尿的能力。不同的药物将在蛋白尿肾病的诱导型和遗传性啮齿动物模型中进行测试。

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 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 foot processes (FPs), highly dynamic actin-based cellular extensions that are connected by slit diaphragms. Most forms of proteinuria and nephrotic syndrome are characterized by transformation of podocyte FPs into a band of cytoplasm due to de- regulation 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 recently shown that dynamin directly regulates the actin cytoskeleton in podocytes. In addition, we have identified small molecules that promote dynamin oligomerization into rings, which in turn protects actin cytoskeleton in podocytes. In this grant application we test the ability of dynamin ring stabilizer drugs to reverse FP effacement and ameliorate proteinuria in different rodent models of proteinuric kidney disease. In Specific Aim 1 we test efficacy of dynamin drugs in inducible models of proteinuric kidney disease such as a rat model of puromycin aminonucleoside (PAN) nephrosis and a rat model of adriamycin nephrosis. In Specific Aim 2 we test efficacy of dynamin ring stabilizer drugs in genetic models of proteinuric kidney diseases such as (1) mouse model in which actin cytoskeleton is mis- regulated due to expression of 'gain of function' 1-actinin 4 mutant; (2) mice lacking CD2AP (adaptor protein involved in regulation of actin cytoskeleton and signaling in podocytes); (3) transgenic mice expressing high levels of TGF-¿1. In Specific Aim 3 we examine whether ring stabilizing drugs effect turnover of the nephrin at the plasma membrane. Our work has potential to identify dynamin drugs as novel therapeutics to treat proteinuric kidney diseases. PUBLIC HEALTH RELEVANCE: In the United States alone, glomerular type of kidney diseases effects some 20 million people, and this number has roughly doubled within the last two decades. Here we propose to test the ability of subset of small molecules (drugs) that specifically target GTPase dynamin to ameliorate proteinuria by restoring podocyte structure and function. Different drugs will be tested in inducible and genetic rodent models of proteinuric kidney diseases.