Role of Rho Kinase in Diabetic Nephropathy

描述(申请人提供)：糖尿病肾病是美国终末期肾病(ESRD)的主要原因，强调了预防其进展的创新疗法的必要性。我们有兴趣了解在糖尿病环境中控制线粒体功能障碍的细胞和分子机制，期望了解这些过程将揭示糖尿病肾病的潜在疾病机制和治疗靶点。目前的建议是基于我们最近发表的观察结果，表明ROCK1介导的线粒体断裂对于促进糖尿病环境中足细胞和肾小球内皮细胞的线粒体功能障碍是必不可少的。对控制肾脏线粒体分裂的机制的详细了解仍然不完整，基于这些机制的治疗靶点也不存在。由于动力蛋白相关蛋白-1(Dynamin-Related Protein-1，Drp1)是调控线粒体分裂的一个组成部分，因此我们重点研究了ROCK1在DRp1易位到线粒体导致线粒体碎裂和细胞凋亡中的作用。我们最近发表的观察结果表明，ROCK1通过促进Drp1向线粒体募集来介导高糖诱导的线粒体碎裂。在db/db糖尿病小鼠中，ROCK1的缺失阻止了线粒体的分裂，而足细胞特异性成分活性(CA)-ROCK1小鼠表现出线粒体分裂的增加。重要的是，我们发现ROCK1通过磷酸化丝氨酸600位的Drp1来触发线粒体分裂。这些发现为ROCK1在调节线粒体动力学的信号级联中的意外作用提供了令人信服的初步证据，并代表了一个可能有助于预防糖尿病肾脏疾病的治疗靶点。考虑到这些结果和在本申请中提出的其他初步数据，该项目将解决这样的假设，即DRp1的磷酸化是糖尿病肾病中线粒体功能障碍的关键特征。这一研究结果将为线粒体形态在糖尿病肾病发生发展中的作用提供重要的新见解，并可能为未来糖尿病肾脏疾病的治疗提供新的治疗靶点。

DESCRIPTION (provided by applicant): Diabetic nephropathy represents the primary cause of end stage renal disease (ESRD) in the US, underscoring the need for innovative therapies for preventing its progression. We are interested in understanding the cellular and molecular mechanisms that govern mitochondrial dysfunction in the diabetic milieu with the expectation that understanding of these processes will expose potential disease mechanisms and therapeutic targets in diabetic nephropathy. The present proposal is based on our recent published observation, indicating that ROCK1-mediated mitochondrial fragmentation is essential for prompting mitochondrial dysfunction in podocytes and glomerular endothelial cells in the diabetic milieu. A detailed understanding of mechanisms that govern mitochondrial fission in the kidney remains incomplete and therapeutic targets based on these mechanisms do not exist. Because dynamin-related protein-1 (Drp1) is an integral part in regulating mitochondrial fission, we have focused on investigating the functions of ROCK1 on Drp1 translocation to the mitochondria resulting in mitochondrial fragmentation and cell apoptosis. We have been guided by our recent published observations that ROCK1 mediates high glucose-induced mitochondrial fragmentation by promoting Drp1 recruitment to the mitochondria. Deletion of ROCK1 in db/db diabetic mice prevented mitochondrial fission, whereas podocyte-specific constitutively active (cA)-ROCK1 mice exhibited increased mitochondrial fission. Importantly, we found that ROCK1 triggers mitochondrial fission by phosphorylating Drp1 at serine 600 residue. These findings provide compelling initial evidence into the unexpected role of ROCK1 in a signaling cascade that regulates mitochondrial dynamics, and represents a therapeutic target that might be useful in preventing diabetic kidney disease. Given these results and additional preliminary data presented in this application, this project will address the hypothesis that phosphorylation of Drp1 is a key feature of mitochondria dysfunction in diabetic nephropathy. The results of this study will provide important new insights into the role of mitochondrial morphology in the development of diabetic nephropathy, and may lead to novel therapeutic targets for the future treatment of diabetic kidney disease.