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；它在糖尿病引起的肾损伤中的作用尚未得到充分研究。糖尿病肾病的特点是肾脏肥大和细胞外基质积聚。 mRNA 翻译是一个能量消耗过程，是蛋白质合成的限速步骤，并且即使在基因表达受转录控制时也是一个调节位点。然而，能量传感器在调节糖尿病引起的肾脏肥大和基质合成的 mRNA 翻译中的作用尚未得到解决。我们希望研究重要的能量传感器 AMP 激活蛋白激酶 (AMPK) 在肾脏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 的磷酸化及其活性降低与高葡萄糖诱导的肾细胞中蛋白质合成和肥大的增加以及基质蛋白合成的增加有关，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。给予二甲双胍和 AICAR 可恢复降低的 AMPK 磷酸化并抑制 1 型糖尿病大鼠中出现的肾脏肥大。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。我们希望检验 AMPK 活性调节 1 型和 2 型糖尿病肾肥大和基质积累的假设。我们的具体目标是： 具体目标 1. 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。将在高血糖条件下研究培养的肾小球上皮细胞、系膜上皮细胞和近端肾小管上皮细胞，这些细胞会诱导细胞肥大，并刺激 mRNA 翻译和基质蛋白的合成。我们将研究改变的 AMP-ATP 含量、LKB-1（AMPK 上游激酶）活性、PI 3-激酶-Akt 轴和 PKC-TGF-3 轴是否作为上游线索来调节 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节。将研究 AMPK 在调节 mRNA 翻译的关键事件起始和延伸阶段中的下游效应；介导 AMPK 效应的信号通路将得到阐明。 (C) 在基质蛋白 mRNA 翻译增强的背景下，探讨 AMPK 在高葡萄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 型糖尿病肾脏病理学中的作用。将在肾肥大的早期（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子的调节，并与蛋白尿的功能变化和GFR的变化相关。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 alpha 敲除小鼠将用于研究 1 型和 2 型糖尿病肾脏异常的演变。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。