Novel mechanisms of diabetic nephropathy

糖尿病肾病的新机制

• 批准号: 7617188
• 负责人: BALAKUNTALAM S KASINATH
• 金额: $ 26.4万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-07-01 至 2012-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7617188
• 关键词: 1-Phosphatidylinositol 3-Kinase; 5' -AMP-activated protein kinase; AMP-activated protein kinase kinase; Accounting; Acetyl-CoA Carboxylase; Address; Affect; Albuminuria; Amides; Antibodies; Binding; Biological Assay; Cells; Chemicals; Collagen Type IV; Complex; Constitution; Consumption; Creatinine clearance measurement; Cues; Data; Diabetes Mellitus; Diabetic Nephropathy; Dimerization; Dissociation; Dominant-Negative Mutation; Dose; Epithelial; Epithelial Cells; Eukaryotic Initiation Factor-4E; Event; Evolution; Extracellular Matrix; Fibronectins; Figs - dietary; Gene Expression; Genetic Transcription; Genetic Translation; Glomerular Mesangial Cell; Glucose; Hyperglycemia; Hypertrophy; Immunoblotting; Immunohistochemistry; In Vitro; Incubated; Injury; Insulin-Dependent Diabetes Mellitus; Kidney; Knockout Mice; Laminin; Mannitol; Mediating; Mediator of activation protein; Messenger RNA; Metformin; Modeling; Mus; Non-Insulin-Dependent Diabetes Mellitus; Oryctolagus cuniculus; Pathologic Processes; Pathology; Pathway interactions; Peptides; Phase; Phospho-Specific Antibodies; Phosphorylation; Phosphotransferases; Play; Principal Investigator; Process; Protein Biosynthesis; Protein Kinase C; Proteins; RNA; RNA Cap-Binding Proteins; Rattus; Recruitment Activity; Regulation; Research Personnel; Reticulocytes; Ribosomes; Rodent; Rodent Model; Role; Signal Pathway; Signal Transduction; Sirolimus; Site; Specific qualifier value; Staging; Streptozocin; Sucrose; System; TSC1 gene; Testing; Time; Translations; Tubular formation; base; blood glucose regulation; cell growth; db/db mouse; diabetic rat; genetic manipulation; human FRAP1 protein; in vitro Assay; in vivo; inhibitor/antagonist; kidney cell; kidney cortex; kinase inhibitor; mTOR Inhibitor; morphometry; novel; programs; research study; sensor; translation assay; type I and type II diabetes; type I diabetic; upstream kinase; urinary

DESCRIPTION (provided by applicant): Energy status of cells is altered by diabetes; its role in diabetes-induced kidney injury is not well studied. Diabetic nephropathy is characterized by renal hypertrophy and extracellular matrix accumulation. mRNA translation, an energy consuming process, is the rate-limiting step in protein synthesis and is a site of regulation even when gene expression is controlled by transcription. However, the role of energy sensors in regulation of mRNA translation underlying diabetes-induced renal hypertrophy and matrix synthesis has not been addressed. We wish to examine the role of an important energy sensor, AMP-activated protein kinase (AMPK), in renal hypertrophy and matrix accumulation. The rationale for these studies is based on the following preliminary data. Phosphorylation of AMPK and its activity are reduced in association with high glucose-induced increase in protein synthesis and hypertrophy, and increase in matrix protein synthesis in renal cells, as well as, in renal cortex and glomeruli of rodents with type 1 or type 2 diabetes at the stage of renal hypertrophy. Administration of metformin and AICAR restores reduced AMPK phosphorylation and inhibits renal hypertrophy seen in the type 1 diabetic rat. However, the role of AMPK in progressive renal injury in type 1 or type 2 diabetes is not known. We wish to test the hypothesis that AMPK activity regulates renal hypertrophy and matrix accumulation in type 1 and type 2 diabetes. Our Specific Aims are: Specific aim 1. In vitro studies. (A) To explore mediators and signaling pathways involved in high glucose regulation of AMPK phosphorylation. Glomerular epithelial, mesangial and proximal tubular epithelial cells in culture will be studied under conditions of hyperglycemia that induce cell hypertrophy, and stimulate mRNA translation and synthesis of matrix proteins. We will investigate if altered AMP-ATP content, activity of LKB-1, an upstream kinase for AMPK, PI 3-kinase-Akt axis, and PKC-TGF-3 axis serve as upstream cues to regulate changes in AMPK phosphorylation and activity. (B) To investigate AMPK regulation of initiation and elongation phases of mRNA translation. The downstream effects of AMPK in regulation of critical events initiation and elongation phases of mRNA translation will be studied; signaling pathways mediating AMPK effect will be elucidated. (C) To explore the role of AMPK in high glucose induced matrix synthesis by renal cells in the context of augmented mRNA translation of matrix proteins. Polyribosomal assays and in vitro translation assays will be employed to define the role of AMPK. Specific aim 2. In vivo studies. To explore role of AMPK in renal pathology in type 1 or type 2 diabetes. Regulation of AMPK phosphorylation by aforementioned upstream factors and its activity and regulation of downstream effectors will be studied in the early stage (4 -14 days) of renal hypertrophy and established stage (3 months) of matrix accumulation and correlated with functional changes in albuminuria and changes in GFR. The ability of AICAR and metformin to inhibit both the anatomical and functional changes induced by diabetes in rodent models of type 1 and type 2 diabetes will be explored. AMPK alphal knock out mice will be studied for evolution of renal abnormalities in type 1 and type 2 diabetes. These studies may identify AMPK as a novel mediator of injury and a treatment target in diabetic nephropathy.

描述（由申请人提供）：糖尿病改变了细胞的能量状态;其在糖尿病诱导的肾损伤中的作用尚未得到充分研究。糖尿病肾病的特征是肾脏肥大和细胞外基质积聚。mRNA翻译是一个能量消耗过程，是蛋白质合成的限速步骤，即使基因表达受转录控制，它也是一个调控位点。然而，能量传感器在糖尿病诱导的肾脏肥大和基质合成的基础上的mRNA翻译调节中的作用尚未得到解决。我们希望研究一个重要的能量传感器，AMP激活的蛋白激酶（AMPK），在肾脏肥大和基质积累的作用。这些研究的基本原理基于以下初步数据。AMPK的磷酸化及其活性的降低与高葡萄糖诱导的蛋白质合成和肥大的增加以及肾细胞中基质蛋白合成的增加以及患有1型或2型糖尿病的啮齿动物在肾肥大阶段的肾皮质和肾小球中的基质蛋白合成的增加相关。二甲双胍和AICAR的给药恢复了1型糖尿病大鼠中观察到的降低的AMPK磷酸化并抑制肾脏肥大。然而，AMPK在1型或2型糖尿病进行性肾损伤中的作用尚不清楚。我们希望验证AMPK活性调节1型和2型糖尿病患者肾脏肥大和基质积聚的假设。我们的目标是：具体目标1。体外研究。(A)目的探讨高糖对AMPK磷酸化的调节机制及信号通路。将在诱导细胞肥大并刺激mRNA翻译和基质蛋白合成的高血糖条件下研究培养的肾小球上皮、系膜和近端肾小管上皮细胞。我们将研究AMP-ATP含量的改变、AMPK上游激酶LKB-1的活性、PI 3-激酶-Akt轴和PKC-TGF-3轴是否作为上游信号调节AMPK磷酸化和活性的变化。(B)研究AMPK对mRNA翻译起始和延伸阶段的调控。研究AMPK在mRNA翻译关键事件起始和延伸阶段的下游调控作用，阐明AMPK作用的信号通路。(C)目的探讨AMPK在高糖诱导的肾细胞基质合成中的作用。将采用多核糖体测定和体外翻译测定来确定AMPK的作用。具体目标2。体内研究。探讨AMPK在1型和2型糖尿病肾脏病理中的作用。将在肾肥大的早期阶段（4 - 14天）和基质积累的建立阶段（3个月）研究上述上游因子对AMPK磷酸化的调节及其活性和下游效应物的调节，并将其与白蛋白尿的功能变化和GFR的变化相关联。将探索AICAR和二甲双胍在1型和2型糖尿病啮齿动物模型中抑制糖尿病诱导的解剖学和功能变化的能力。将研究AMPK肾脏敲除小鼠在1型和2型糖尿病中肾脏异常的演变。这些研究可能将AMPK确定为一种新型损伤介质和糖尿病肾病的治疗靶点。