The Role of Angiotensin II on mTOR mediated Tubulointerstitial Fibrosis

血管紧张素 II 对 mTOR 介导的肾小管间质纤维化的作用

• 批准号: 8183530
• 负责人: Adam T Whaley Connell
• 金额: $ 7.32万
• 依托单位: UNIVERSITY OF MISSOURI-COLUMBIA
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-01 至 2013-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8183530
• 关键词: Adhesions; Age; Aging; Agonist; Angiotensin II; Area; Atrophic; Blood flow; Cadherins; Caring; Cell Adhesion Molecules; Cell Proliferation; Cell Survival; Cells; Chronic Disease; Chronic Kidney Failure; Clinical; Complex; Data; Development; Diabetic Nephropathy; Disease model; Elderly; End stage renal failure; Epithelial; Epithelial Cells; Expenditure; Extracellular Matrix Degradation; Fibrosis; Functional disorder; Funding; Future; Gap Junctions; Generations; Genetic Transcription; Goals; Healthcare; Infusion procedures; Interruption; Intervention; Juxtaglomerular Apparatus; Kidney; Kidney Diseases; Knowledge; Measures; Mediating; Modeling; N-Cadherin; Nephrons; Nutrient; Pathway interactions; Patients; Perfusion; Phosphorylation; Physiological; Plasma; Positioning Attribute; Process; Protein Biosynthesis; Protein-Serine-Threonine Kinases; Proteins; RNA Interference; Rattus; Receptor, Angiotensin, Type 1; Regulation; Renal function; Renin; Renin-Angiotensin System; Research; Risk Factors; Rodent; Rodent Model; Role; Scheme; Staging; Stress; Transmission Electron Microscopy; Tubular formation; Work; age related; aged; aging population; cell growth; clinically relevant; hemodynamics; improved; interest; mTOR protein; novel; pre-clinical; prevent; receptor; response; senescence; skills

DESCRIPTION (provided by applicant): Our proposal seeks to investigate the impact of angiotensin (Ang) II on the aging kidney and tubulointerstitial fibrosis, a mechanism that correlates with progressive kidney disease in aging. Tubulointerstitial fibrosis is the predominant histomorphologic finding that predicts progression of clinical kidney disease. Sufficient data exist to support that blockade of the Ang II type 1 receptor (AT1R) has been shown to improve tubulointerstitial fibrosis and progression of kidney disease; however, the burden of CKD and ESRD remains high in our elderly despite widespread use of AT1R blockade. This highlights the need to investigate strategies to prevent progressive CKD. In this context, there has been tremendous interest in targeting reductions in mammalian Target of Rapamycin (mTOR)/S6K1 activity to improve tubulointerstitial fibrosis and kidney function in polycystic and diabetic kidney disease models. mTOR holds a strategic position at the nexus of nutrient/stress sensing pathways that contribute to the importance of TOR/S6K1 function in regulating chronic disease and in aging. Our preliminary data suggest that Ang II contributes directly to activation of mTOR and S6K1 resulting in tubulointerstitial fibrosis. Our data further suggest the mechanism occurs through loss of adhesion molecules such as the proximal tubule specific N-cadherin and promotion of epithelial-mesynchymal transition (EMT). Cadherin loss is a critical first step in tubulointerstitial fibrosis through EMT. Understanding of agonists that elicit EMT and loss of adhesion are limited in tubulointerstitial fibrosis and progressive kidney disease, especially in the context of aging. Thereby, this preclinical proposal broadly serves to investigate a novel mechanism that serves a significant area of clinical need with interventions that have direct clinical relevance. Our aims have been developed to target early tubulointerstitial fibrosis in order to prevent progressive kidney disease in aging. In our work proposed, in Specific Aim I we will examine the role of Ang II activation of mTOR/S6K1 and loss of the proximal tubule specific adhesion molecule N-cadherin in relation to EMT and tubulointerstitial fibrosis in progressive kidney disease in an aging rodent model. We will then explore activation/phosphorylation of mTOR and S6K1 and the novel role for loss of N-cadherin expression in early stage tubulointerstitial fibrosis on histomorphologic and immunohistochemical analysis as well as EMT via ultrastructural analysis with transmission electron microscopy. To further explore the specific role of mTOR/S6K1 roles on N-cadherin loss, in Specific Aim 2 we will focus on utilization of knockdown strategies with RNA silencing to delineate the specific complex within the proximal tubule that dictates loss of N-cadherin. We propose RNAi of AT1R, mTORC1/S6K1 in primary culture of aging proximal tubule cells and measure N-cadherin in conjunction with specific markers of EMT and fibrosis. PUBLIC HEALTH RELEVANCE: Aging is a leading risk factor for kidney disease and care for chronic kidney disease (CKD) and end-stage renal disease (ESRD) is one of the leading healthcare expenditures in the US. Tubulointerstitial fibrosis is the predominant finding that predicts progression of kidney disease. However, our understanding of mechanisms that elicit fibrosis and progressive kidney disease in aging remain limited. This highlights the need to investigate strategies that interrupt this mechanism at early stages to prevent progressive CKD in the aging population. Thereby, our proposal seeks to investigate a novel mechanism that contributes to the early development of tubulointerstitial fibrosis with interruptions schemes that have direct clinical relevance.

描述（由申请人提供）：我们的提案旨在研究血管紧张素 (Ang) II 对衰老肾脏和肾小管间质纤维化的影响，这是一种与衰老过程中进行性肾脏疾病相关的机制。肾小管间质纤维化是预测临床肾脏疾病进展的主要组织形态学发现。已有足够的数据支持，阻断 Ang II 1 型受体 (AT1R) 已被证明可以改善肾小管间质纤维化和肾脏疾病的进展；然而，尽管广泛使用 AT1R 阻断剂，但 CKD 和 ESRD 的负担在老年人中仍然很高。这凸显了研究预防进行性 CKD 策略的必要性。在这种背景下，人们对降低哺乳动物雷帕霉素靶标 (mTOR)/S6K1 活性以改善多囊肾病和糖尿病肾病模型中的肾小管间质纤维化和肾功能产生了极大的兴趣。 mTOR 在营养/压力传感通路的联系中占据着战略地位，这有助于 TOR/S6K1 功能在调节慢性疾病和衰老方面发挥重要作用。 我们的初步数据表明，Ang II 直接促进 mTOR 和 S6K1 的激活，导致肾小管间质纤维化。我们的数据进一步表明，该机制是通过近端小管特异性 N-钙粘蛋白等粘附分子的丧失和上皮-间质转化 (EMT) 的促进而发生的。钙粘蛋白损失是 EMT 导致肾小管间质纤维化的关键第一步。对于引起 EMT 和粘附丧失的激动剂在肾小管间质纤维化和进行性肾脏疾病方面的了解有限，特别是在衰老的情况下。 因此，这一临床前提案广泛用于研究一种新机制，该机制通过具有直接临床相关性的干预措施满足临床需求的重要领域。我们的目标是针对早期肾小管间质纤维化，以预防衰老过程中的进行性肾脏疾病。在我们提出的工作中，在具体目标 I 中，我们将研究老年啮齿动物模型中进行性肾病中 mTOR/S6K1 的 Ang II 激活和近曲小管特异性粘附分子 N-钙粘蛋白的丧失与 EMT 和肾小管间质纤维化的关系。然后，我们将通过组织形态学和免疫组织化学分析以及通过透射电子显微镜超微结构分析的 EMT 来探索 mTOR 和 S6K1 的激活/磷酸化，以及早期肾小管间质纤维化中 N-钙粘蛋白表达缺失的新作用。为了进一步探讨 mTOR/S6K1 对 N-钙粘蛋白丢失的具体作用，在具体目标 2 中，我们将重点关注利用 RNA 沉默的敲低策略来描绘近端小管内决定 N-钙粘蛋白丢失的特定复合物。我们建议在老化近端小管细胞的原代培养物中对 AT1R、mTORC1/S6K1 进行 RNAi，并结合 EMT 和纤维化的特定标记物来测量 N-钙粘蛋白。 公共健康相关性：老龄化是肾脏疾病的主要危险因素，慢性肾脏病 (CKD) 和终末期肾病 (ESRD) 的护理是美国主要的医疗保健支出之一。肾小管间质纤维化是预测肾脏疾病进展的主要发现。然而，我们对衰老过程中引发纤维化和进行性肾病的机制的理解仍然有限。这凸显了需要研究在早期阶段中断这一机制的策略，以预防老龄化人群中进行性 CKD。因此，我们的建议旨在研究一种有助于肾小管间质纤维化早期发展的新机制，并采用具有直接临床相关性的中断方案。