Transcriptional control of mitochondrial function by KLF6 in diabetic kidney disease

项目摘要/摘要 疾病控制和预防中心估计，在美国，超过10%的成年人 2000万美国人患有慢性肾脏疾病。糖尿病是慢性阻塞性肺疾病的主要危险因素 肾脏疾病在美国。尽管血糖控制有所改善，但糖尿病患者 继续发展为糖尿病肾病(DKD)。在DKD中，伴随着内皮损伤和 肾小球系膜扩张、足细胞丢失直接影响维持肾滤过的功能能力 障碍。线粒体损伤在DKD中也是一致的，并伴有线粒体DNA 参与线粒体生物发生、功能和基因表达的损伤和改变 碎片化。我们最近报道了锌指转录因子Krüppel样因子的重要作用 KLF6)，足细胞损伤。具体地说，我们证明了KLF6是一种早期可诱导的损伤反应 增强线粒体呼吸复合体IV(细胞色素c氧化酶，COX)表达的基因，从而 在细胞应激状态下，消除细胞色素c的释放和细胞凋亡的激活。KLF6维护 COX装配通过调节线粒体复制中的关键转录本的表达， 转录，并在细胞压力下发挥作用。到目前为止，这是第一个展示了直接监管的研究 锌指转录因子对足细胞线粒体功能的影响。我们的初步数据也 提示足细胞特异性的KLF6缺失(KLF6-/-)加速了小鼠的DKD。此外，我们观察到一个 与糖尿病KLF6-/-小鼠相比，糖尿病KLF6-/-小鼠足细胞丢失的线粒体损伤显著增加 糖尿病野生型小鼠。此外，我们观察到，调节足细胞中KLF6的表达水平 直接调控线粒体的结构、功能、参与环氧合酶组装的基因和细胞凋亡。最后， 与健康对照组相比，DKD患者KLF6在三个独立基因中的表达降低 来自人类肾脏活检组织的表达阵列。这项研究提案的目的是证明 KLF6是预防DKD患者线粒体功能障碍和足细胞损伤所必需的。的长期目标是 我们的项目是确定在恢复糖尿病肾脏足细胞线粒体功能方面的“可用药”靶点。 这项提案将通过证明COX组装对于 预防糖尿病肾脏足细胞线粒体功能障碍。这一提议的潜在影响 研究表明，这将为呼吸复合体组装在改善人类健康方面的关键作用提供新的线索。 足细胞中线粒体的功能和减缓肾脏DKD进展的速度。最后， 破译KLF6调节COX组装的机制将为我们提供一条新的途径 DKD中的目标。

Project Summary/Abstract The Centers for Disease Control and Prevention estimates more than 10% of adults in the United States, over 20 million Americans have chronic kidney disease. Diabetes Mellitus is the leading risk factor for chronic kidney disease in the United States. Despite improved glycemic control, individuals with Diabetes Mellitus continue to develop and progress to diabetic kidney disease (DKD). In DKD, along with endothelial injury and mesangial expansion, podocyte loss directly contributes to the functional capacity to maintain the renal filtration barrier. Mitochondrial injury is also uniformly observed in DKD and is accompanied by mitochondrial DNA damage as well as altered expression of genes involved in mitochondrial biogenesis, function, and fragmentation. We recently reported the essential role for the zinc-finger transcription factor, Krüppel-like factor 6 (KLF6), in podocyte injury. Specifically, we demonstrated that KLF6 is an early inducible injury response gene that enhances mitochondrial respiratory complex IV (cytochrome c oxidase, COX) expression, thereby abrogating the release of cytochrome c and activation of apoptosis in the setting of cell stress. KLF6 maintains COX assembly by regulating the expression of key transcripts involved in mitochondrial replication, transcription, and function under cell stress. To date, this is the first study demonstrating a direct regulatory effect of a zinc-finger transcription factor on mitochondrial function in the podocyte. Our preliminary data also suggests that podocyte-specific loss of Klf6 (Klf6-/-) accelerated DKD in mice. In addition, we observed a significant increase in mitochondrial injury with podocyte loss in the diabetic Klf6-/- mice as compared to diabetic wildtype mice. Furthermore, we observed that modulating the level of KLF6 expression in the podocyte directly regulated mitochondrial structure, function, genes involved in COX assembly, and apoptosis. Finally, KLF6 expression was reduced in DKD as compared to healthy control subjects in three independent gene expression arrays from human kidney biopsies. The objective of this research proposal is to demonstrate that KLF6 is required to prevent mitochondrial dysfunction and podocyte injury in DKD. The long-term goal of our project is to identify “druggable” targets in restoring mitochondrial function in podocytes of diabetic kidney. This proposal will address a current gap in the field by demonstrating that COX assembly is critical to preventing mitochondrial dysfunction in podocytes of diabetic kidney. The potential impact of this proposed research is that it will shed new light on the critical role of respiratory complex assembly in improving mitochondrial function in the podocyte and slowing the rate of DKD progression in the kidney. Finally, deciphering the mechanism by which KLF6 regulates COX assembly will provide us with a novel pathway to target in DKD.