Novel mechanisms of diabetic nephropathy

糖尿病肾病的新机制

• 批准号: 7315490
• 负责人: BALAKUNTALAM S KASINATH
• 金额: $ 26.52万
• 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/7315490
• 关键词: 1-Phosphatidylinositol 3-Kinase; 5' -AMP-activated protein kinase; AICA ribonucleotide; AMP-activated protein kinase kinase; Accounting; Acetyl-CoA Carboxylase; Address; Affect; Albuminuria; Amides; Antibodies; Binding; Biological Assay; Cells; Chemicals; Collagen Type IV; Complex; Condition; 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; LY294002; 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; Principal Investigator; Process; Protein Biosynthesis; Protein Kinase C; Proteins; RNA; RNA Cap-Binding Proteins; Rate; Rattus; Recruitment Activity; Regulation; Research Personnel; Reticulocytes; Ribosomes; Rodent; Rodent Model; Role; Role playing therapy; Signal Pathway; Signal Transduction; Sirolimus; Site; Specific qualifier value; Staging; Streptozocin; Sucrose; System; Testing; Thinking; Time; Translations; Tubular formation; base; blood glucose regulation; cell growth; day; 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）：细胞的能量状态因糖尿病而改变；其在糖尿病引起的肾损伤中的作用尚未得到很好的研究。糖尿病肾病的特点是肾脏肥大和细胞外基质积聚。mRNA翻译是一个消耗能量的过程，是蛋白质合成的限速步骤，即使基因表达受转录控制，也是一个调控位点。然而，能量传感器在糖尿病诱导的肾肥大和基质合成的mRNA翻译调控中的作用尚未得到解决。我们希望研究一种重要的能量传感器，amp活化蛋白激酶（AMPK）在肾肥大和基质积累中的作用。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糖诱导的蛋白质合成和肥厚的增加以及肾细胞中基质蛋白合成的增加以及1型或2型糖尿病啮齿动物肾脏肥大阶段的肾皮质和肾小球中基质蛋白合成的增加有关。二甲双胍和AICAR可恢复1型糖尿病大鼠AMPK磷酸化降低并抑制肾肥大。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型糖尿病的肾肥大和基质积累的假设。我们的具体目标是：体外研究。(A)探索参与高糖调节AMPK磷酸化的介质和信号通路。培养的肾小球上皮细胞、系膜上皮细胞和近端小管上皮细胞将在高血糖诱导细胞肥大、刺激mRNA翻译和基质蛋白合成的条件下进行研究。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翻译起始期和延伸期的调控。将研究AMPK在mRNA翻译起始和延伸阶段的关键事件调控中的下游作用；介导AMPK作用的信号通路将被阐明。(C)在增强基质蛋白mRNA翻译的情况下，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型或2型糖尿病肾脏病理中的作用。上述上游因子对AMPK磷酸化的调控及其活性和对下游效应物的调控将在肾肥大早期（4 -14天）和基质积累成长期（3个月）进行研究，并与蛋白尿功能变化和GFR变化相关。我们将探讨AICAR和二甲双胍抑制1型和2型糖尿病啮齿动物模型中糖尿病引起的解剖和功能变化的能力。AMPK α敲除小鼠将被研究1型和2型糖尿病肾脏异常的进化。这些研究可能确定AMPK作为一种新的损伤介质和糖尿病肾病的治疗靶点。