KIM-1, microparticles and diabetic tubular injury

KIM-1、微粒和糖尿病肾小管损伤

• 批准号: 8214447
• 负责人: Xueying Zhao
• 金额: $ 14.15万
• 依托单位: MOREHOUSE SCHOOL OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-03-01 至 2015-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8214447
• 关键词: Accounting; Address; Albumins; Albuminuria; Animal Model; Apoptosis; Apoptotic; Atrophic; Biological Markers; Cell Culture Techniques; Cell Survival; Cell membrane; Cells; Coculture Techniques; Data; Diabetes Mellitus; Diabetic Nephropathy; Disease Management; Disease Progression; Elements; End stage renal failure; Epithelial; Epithelial Cells; Figs - dietary; Functional disorder; Glucose; Goals; Human; In Vitro; Injury; Ischemia; Kidney; Kidney Diseases; Light; Mediator of activation protein; Modeling; Molecular; Mus; Pathogenesis; Pathway interactions; Pattern; Phagocytosis; Pharmaceutical Preparations; Pilot Projects; Proteins; Proteinuria; Rattus; Research; Resistance; Rodent; Role; Series; Signal Transduction; Stimulus; Stress; Testing; Tight Junctions; Tubular formation; Up-Regulation; Urine; Vesicle; base; caspase-3; cell injury; diabetic; diabetic rat; gain of function; in vivo; insight; monolayer; novel therapeutics; oxidized low density lipoprotein; prevent; rat KIM-1 protein; response; scavenger receptor; submicron; uptake; urinary

DESCRIPTION (provided by applicant): Diabetic nephropathy is now the most prevalent cause of end stage renal disease, accounting for 40-50% 1, and apoptosis has been shown to be an important mechanism for tubular atrophy, a sensitive predictor of disease progression. As the submicron vesicles shed from plasma membranes, microparticles (MPs) are found in the urine of healthy humans and rodents and their contents and amounts are altered following cell activation and apoptosis. The overall goal of the proposed studies is to uncover the mechanisms leading to renal secretion of MPs and their role in tubular injury in diabetes. Kidney injury molecule-1 (KIM-1) is a urinary biomarker for renal proximal tubular damage and has been recently identified as a scavenger receptor involved in epithelial phagocytosis. We found that tubular expression of KIM-1 was dramatically increased, in association with proteinuria and kidney injury, in Zucker diabetic fatty rats. In vitro studies using primary cultures of rat and mouse tubular cells revealed that albumin increased expression and vesicular accumulation of KIM-1 as well as its secretion via MP shedding. Moreover, this increase in KIM-1 expression was associated with an elevation of caspase-3 activity. Interestingly, knockdown of KIM-1 confers resistance to epithelial apoptosis as reflected by an up-regulation of bcl-2 and suppression of caspase-3 activation. We conducted additional pilot study indicating that tubular epithelial cells were capable of uptaking MPs and that the internalization of MPs containing KIM-1 (KIM-MPs) disrupted normal tight junction in tubular epithelial monolayer. Therefore, those preliminary results prompted our central hypothesis stating that "KIM-1/KIM- MPs contribute to tubular dysfunction by promoting cell injury and apoptosis". Specifically, we will address the following aims: Aim I. To test the hypothesis that tubular expression and secretion of KIM-1 are increased in response to albumin overload. Systematic analyses will be conducted to delineate expression, localization and secretion of KIM-1 in tubular epithelial cells in response to albumin overload and other apoptotic stimuli in both in vivo animal model and in vitro cell culture model. Aim II. To test the hypothesis that KIM-1/KIM-MPs contribute to tubular cell injury and apoptosis. The effects of KIM-1/KIM-MPs on tubular cell injury and apoptosis in response to albumin and other apoptotic stimuli will be determined by 1) examining the effects of loss- and gain-of-function of KIM-1 on tubular cell injury and apoptosis, 2) delineating the apoptotic pathways by which KIM-1 contributes to tubular cell apoptosis upon apoptotic stimulation, 3) determining the effects of KIM-MPs on the target cells by treating normal tubular epithelial cell monolayer with KIM-1 positive or KIM-1 negative microparticles. Together, the series of studies outlined in Aims I and II will enable us to provide new insights into the functional role of KIM-1/KIM-MPs in tubular injury and dysfunction associated with diabetic kidney disease. Our studies will also shed light on KIM-1/KIM-MPs as attractive targets for kidney disease management. PUBLIC HEALTH RELEVANCE: Diabetic nephropathy is the most common cause of end-stage renal disease. Tubular cell injury and apoptosis are important mechanisms for disease progression. However, the signaling elements and molecular mediators involved in diabetic tubular injury are still unclear. The proposed research will enable us to establish new therapeutic strategies to prevent and treat diabetic kidney disease in humans by examining the role of kidney injury molecule-1 (KIM-1) and KIM-1 containing microparticles in the pathogenesis of tubular injury and dysfunction in diabetes.

描述(申请人提供)：糖尿病肾病目前是终末期肾脏疾病最常见的原因，占40-50%1，细胞凋亡已被证明是肾小管萎缩的重要机制，它是疾病进展的敏感预测指标。在健康人和啮齿动物的尿液中发现有亚微米小泡从质膜上脱落，其含量和数量会随着细胞的活化和凋亡而发生变化。这项研究的总体目标是揭示糖尿病患者肾脏分泌MPS的机制及其在肾小管损伤中的作用。肾损伤分子-1(Kim-1)是肾脏近端小管损伤的尿液生物标志物，最近被确定为参与上皮吞噬作用的清道夫受体。我们发现，在Zucker糖尿病肥胖大鼠中，肾小管中Kim-1的表达显著增加，这与蛋白尿和肾脏损伤有关。采用原代培养的大鼠和小鼠肾小管上皮细胞的体外研究表明，白蛋白增加了Kim-1的表达和囊泡积累，并通过MP脱落增加了其分泌。此外，这种Kim-1表达的增加与caspase-3活性的升高有关。有趣的是，KIM-1基因被敲除可以抵抗上皮细胞的凋亡，表现为bcl2的上调和caspase-3的激活被抑制。我们进行了另一项初步研究，表明肾小管上皮细胞能够摄取MPS，并且含有Kim-1的MPS内化破坏了肾小管上皮单层的正常紧密连接。因此，这些初步结果提示我们的中心假设：“Kim-1/Kim-MPS通过促进细胞损伤和凋亡而导致肾小管功能障碍”。具体地说，我们将解决以下目标：目的1.检验白蛋白超载导致肾小管上皮细胞Kim-1表达和分泌增加的假说。在体内动物模型和体外细胞培养模型中，将对肾小管上皮细胞中Kim-1的表达、定位和分泌进行系统分析，以响应白蛋白超载和其他凋亡刺激。目的II.验证Kim-1/Kim-MPS参与肾小管细胞损伤和凋亡的假说。Kim-1/Kim-MPS在白蛋白和其他凋亡刺激下对肾小管上皮细胞损伤和凋亡的影响将通过以下步骤确定：1)检测Kim-1功能丧失和功能丧失对肾小管细胞损伤和凋亡的影响；2)描绘Kim-1在凋亡刺激下促进肾小管细胞凋亡的凋亡途径；3)通过用Kim-1阳性或阴性微粒处理正常肾小管上皮细胞单层来确定Kim-MPS对靶细胞的影响。总之，AIMS I和II中概述的一系列研究将使我们能够对Kim-1/Kim-MPS在糖尿病肾病相关的肾小管损伤和功能障碍中的功能作用提供新的见解。我们的研究还将阐明Kim-1/Kim-MPS作为肾脏疾病治疗的有吸引力的靶点。 公共卫生相关性：糖尿病肾病是终末期肾病最常见的原因。肾小管上皮细胞损伤和细胞凋亡是疾病进展的重要机制。然而，糖尿病肾小管损伤的信号转导元件和分子介质仍不清楚。这项拟议的研究将使我们能够通过检测肾脏损伤分子-1(Kim-1)和含有KIM-1的微粒在糖尿病肾小管损伤和功能障碍的发病机制中的作用，来建立预防和治疗人类糖尿病肾脏疾病的新的治疗策略。