Role of TSC-mTORC1 pathway for podocyte injury in diabetic nephropathy

TSC-mTORC1 通路在糖尿病肾病足细胞损伤中的作用

• 批准号: 8527765
• 负责人: Ken Inoki
• 金额: $ 30.27万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2014-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8527765
• 关键词: Albuminuria; Attention; Autophagocytosis; Cell physiology; Complex; Data; Development; Diabetes Mellitus; Diabetic Nephropathy; Disease; End stage renal failure; Epithelial Cells; Foot Process; Genetic Transcription; Glomerular Capillary; Glucose; Goals; Growth; Growth Factor; Health; Hyperglycemia; Hypertrophy; Injury; Insulin-Dependent Diabetes Mellitus; Investigation; Lead; Microalbuminuria; Molecular; Mus; Non-Insulin-Dependent Diabetes Mellitus; Nutrient; Pathogenesis; Pathway interactions; Patients; Play; Prevalence; Prevention; Proteins; Proteinuria; Raptors; Regulation; Resistance; Role; Scientist; Serum Proteins; Signal Pathway; Sirolimus; Site; Staging; Surface; TSC1 gene; Translations; diabetic; diabetic patient; glomerular basement membrane; glomerulosclerosis; human FRAP1 protein; in vivo; mTOR Inhibitor; mimetics; mouse model; nephrin; non-diabetic; novel; novel strategies; novel therapeutic intervention; podocyte; prevent; slit diaphragm; type I and type II diabetes

DESCRIPTION (provided by applicant): Diabetic nephropathy (DN) is among the most lethal complications that occur in patients with both type 1 and type 2 diabetes. It is characterized as a major glomerulopathy that develops to glomerulosclerosis, leading ultimately to end-stage renal disease (ESRD). Despite considerable attention from both clinicians and basic scientists, the prevalence of ESRD in diabetic patients is increasing dramatically. Thus, understanding the pathogenesis of DN is crucial to developing new approaches for its prevention and treatment. Recent investigations have revealed that injuries to podocytes play a critical role in the development of diabetic nephropathy. These highly differentiated glomerular epithelial cells and their foot processes comprise the slit diaphragm, a barrier for repelling serum proteins on the surface of glomerular capillaries. Podocyte injury may produce micro-albuminuria, an early feature of DN. The molecular mechanisms by which diabetes causes podocyte injury remain unclear. Furthermore, whether podocyte injury is a cause or a consequence of DN also continues to be uncertain. The TSC-mTORC1 pathway is an evolutionarily conserved signaling pathway that regulates growth and survival. This pathway responds to nutrients such as glucose and growth factors, and in turn controls a wide array of cellular processes such as translation, transcription, and autophagy. We have shown that activation of the mTORC1 pathway plays a critical role in diabetes-dependent podocyte injury. Our studies indicate that all pathological alterations present in a mouse model of DN, including podocyte morphological changes, glomerular basement membrane (GBM) thickening, proteinuria, glomerular hypertrophy, and mesangial expansion, can be prevented by treatment with rapamycin, a specific mTOR inhibitor. Moreover, podocyte-specific mTORC1 activation in a non-diabetic mouse recapitulated podocyte injury and other features of DN in a rapamycin-sensitive manner. These observations indicate a critical role for the site-specific activation of mTORC1 in podocytes during the development of DN. To explore this possibility in greater detail, I will focus on understanding how the TSC-mTORC1 pathway is regulated in podocytes during diabetes; the molecular mechanisms underlying mTORC1-dependent podocyte injury; and whether activation of mTORC1 in podocytes is sufficient to produce DN. I anticipate that these studies will reveal much about the molecular mechanisms underlying podocyte injury in DN, and provide important clues for developing new approaches to the treatment of this debilitating disease. PUBLIC HEALTH RELEVANCE: Recent investigations have revealed that injuries to podocytes play a critical role in the development of diabetic nephropathy (DN). The goal of this proposal is to elucidate the role of mTOR pathway as a molecular mechanism underlying podocyte injury in DN. Completion of this project will not only reveal a novel molecular mechanism for podocyte injury but also set the stage for additional studies to explore new therapeutic approaches to the treatment of DN.

描述（由申请人提供）：糖尿病肾病 (DN) 是 1 型和 2 型糖尿病患者中最致命的并发症之一。它的特征是一种严重的肾小球病，发展为肾小球硬化，最终导致终末期肾病（ESRD）。尽管临床医生和基础科学家都给予了相当多的关注，但糖尿病患者中 ESRD 的患病率仍在急剧增加。因此，了解 DN 的发病机制对于开发新的预防和治疗方法至关重要。最近的研究表明，足细胞损伤在糖尿病肾病的发展中起着至关重要的作用。这些高度分化的肾小球上皮细胞及其足突组成了狭缝隔膜，这是排斥肾小球毛细血管表面血清蛋白的屏障。足细胞损伤可能会产生微量白蛋白尿，这是 DN 的早期特征。糖尿病引起足细胞损伤的分子机制仍不清楚。此外，足细胞损伤是 DN 的原因还是结果也仍然不确定。 TSC-mTORC1 通路是一条进化上保守的信号通路，可调节生长和存活。该通路对葡萄糖和生长因子等营养物质做出反应，进而控制多种细胞过程，如翻译、转录和自噬。我们已经证明 mTORC1 通路的激活在糖尿病依赖性足细胞损伤中发挥着关键作用。我们的研究表明，DN 小鼠模型中存在的所有病理改变，包括足细胞形态变化、肾小球基底膜 (GBM) 增厚、蛋白尿、肾小球肥大和系膜扩张，都可以通过雷帕霉素（一种特定的 mTOR 抑制剂）治疗来预防。此外，非糖尿病小鼠足细胞特异性 mTORC1 激活以雷帕霉素敏感的方式重现了足细胞损伤和 DN 的其他特征。这些观察结果表明足细胞中 mTORC1 的位点特异性激活在 DN 的发展过程中发挥着关键作用。为了更详细地探讨这种可能性，我将重点了解糖尿病期间足细胞中 TSC-mTORC1 通路是如何受到调节的； mTORC1依赖性足细胞损伤的分子机制；足细胞中 mTORC1 的激活是否足以产生 DN。我预计这些研究将揭示 DN 足细胞损伤的分子机制，并为开发治疗这种衰弱性疾病的新方法提供重要线索。公共健康相关性：最近的研究表明，足细胞损伤在糖尿病肾病 (DN) 的发展中起着至关重要的作用。本提案的目的是阐明 mTOR 通路作为 DN 足细胞损伤分子机制的作用。该项目的完成不仅将揭示足细胞损伤的新分子机制，而且为进一步研究探索治疗 DN 的新治疗方法奠定了基础。