Pathogenesis of Diabetic Nephropathy

糖尿病肾病的发病机制

基本信息

批准号：
8546328
负责人：
Yashpal S. Kanwar
金额：
$ 32.43万
依托单位：
NORTHWESTERN UNIVERSITY AT CHICAGO
依托单位国家：
美国
项目类别：
财政年份：
2002
资助国家：
美国
起止时间：
2002-02-15 至 2017-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8546328
关键词：
Affect Aldehyde Reductase Antioxidants Apoptosis Apoptotic Attention Biochemical Biogenesis Biology Breeding Carboxy-Lyases Cell Cycle Proteins Cells Cicatrix Complex Crystalline Lens D-Xylulose reductase Data Deacetylation Dependency Diabetes Mellitus Diabetic Nephropathy Dialysis procedure Diet End stage renal failure Energy Metabolism Enzymes Epithelial Event Expenditure Extracellular Matrix Extracellular Matrix Proteins Family Fatty acid glycerol esters Fibrosis Functional disorder GTP Binding Gene Deletion Generations Genes Genetic Genetic Transcription Glucose Glucuronates Glucuronic Acids Heterozygote Hypoxia In Vitro Injury Inositol Insulin Insulin Resistance Interruption Kidney Knockout Mice MEKs Metabolic Metabolic syndrome Metabolism Methods Mitochondria Molecular Mus Mutation NADH NADP Nonesterified Fatty Acids Obesity Oxidants Oxidation-Reduction Oxidoreductase Pathogenesis Pathway interactions Patients Pentoses Physiological Play Population Production Progress Reports Protein Kinase C Proteins Publishing Reactive Oxygen Species Role Signal Pathway Signal Transduction Smad Proteins Smad protein Specificity Streptozocin Stress Testing Transcription Coactivator Tubular formation Xylitol Xylulokinase Xylulose catalase enzyme pathway feeding gulonic acid in vivo inhibitor/antagonist inositol oxygenase interstitial interstitial cell kidney cell mitochondrial dysfunction mutant novel therapeutics overexpression oxidant stress polyol research study transcription factor

项目摘要

DESCRIPTION (provided by applicant): Overall objective of the proposal is to delineate the role of a proximal tubular specific enzyme, i.e., myo- inositol oxygenase (MIOX), in tubulo-interstitial pathobiology in the context of diabetic nephropathy (DN). The DN is characterized by perturbation in various metabolic/cellular signaling pathways in renal cells resulting in the generation of reactive oxygen species (ROS). The latter have emerged as central to the pathogenesis of DN. The metabolic/signaling events have been delineated largely in renal glomerular cells, and information relating to tubulointerstitial cells is limited. Glucose responsie MIOX catabolizes myo-inositol to D-glucuronate via Glucuronate-Xylulose (GX) pathway, as described in "eye lens", and its metabolites enter pentose pathway. The GX pathway initiated by MIOX leads to "redox imbalance" with perturbed NADPH:NADP+ and NAD+:NADH ratios at 4 steps [Fig. 1], akin to polyol pathway; suggesting that its activation would induce oxidant and hypoxic stress culminating into an increased synthesis of ECM proteins and tubulo-interstitial injury in DN [Fig. 2]. Perturbed NAD+/NADH ratio would also cause depletion of NAD+, as a result the activity of NAD-dependent deacetylases, Sirutins, are compromised. Targets of Sirutins include FOXO family transcription factors and transcriptional coactivator PGC-1¿, which modulate mitochondrial biogenesis and various antioxidant genes. With these perturbations the tubular cells are likely to undergo energy stress and apoptosis. Our published (JBC 2011, AJP 2010) and preliminary data suggest that ROS are generated in the GX pathway, which in turn increases the transcription of MIOX, thus setting up cyclic generation of ROS. Data also suggest that GX pathway exist in the kidney [Fig. 4], and oxidant stress does occur in the tubular compartment in patients with DN [Fig. 3]. Also, MIOX over-expression in high glucose leads to accentuated synthesis of ECM proteins [Fig. 10]. With this background and to achieve objectives of the proposal the following 3 specific aims are proposed. AIM I is to delineate mechanisms by which MIOX overexpression in vitro in tubular cells leads to accentuation of the oxidant stress, mitochondrial dysfunctions and ECM synthesis in the presence of high glucose. Status of NADPH:NADP+ & NAD+:NADH ratios, GSH, NOX4, PKC, TGF-, SIRTs, transcription factors, mitochondrial dynamics, and pro- and anti-apoptotic genes will be assessed. Specific inhibitors/activators will be used to test the specificity of MIOX effects. AIM II is to characterie in vivo MIOX-induced GX pathway, redox imbalance and downstream signaling events leading to dysfunctions of SIRTs and mitochondria, apoptosis and tubulo- interstitial fibrosis. CD1 mice with STZ-induced diabetes and mice over-expressing MIOX cross bred with Akita mice will be used. AIM III is to determine if MIOX gene deletion leads to amelioration in renal dysfunctions and progression to tubulo-interstitial injury in STZ-induced diabetes in heterozygote (+/-) mice and when the mutant Null (-/-) mice are cross bred with Akita mice. It is anticipated that the characterization of GX-SIRT pathway would aid in devising novel therapeutic strategies to decelerate tubulo-interstitial injury in DN.

描述（由适用提供）：该提案的总体目标是描述近端管状特异性酶的作用，即肌醇 - 磷酸氧酶（MIOX），在糖尿病性肾病（DN）中，在微管互化病理生物学中。 DN的特征是在肾细胞中各种代谢/细胞信号通路中扰动，导致活性氧（ROS）产生。后者已经成为DN发病机理的核心。代谢/信号传导事件已在肾肾小球细胞中大部分描绘出来，与小管间质细胞有关的信息受到限制。如“眼镜镜头”中所述，葡萄糖负责任miox通过葡萄糖醛酸氯糖（GX）途径分解了肌氨硫醇，通过葡萄糖醛酸二甲糖（GX）途径与D-葡萄糖醛酸醛酸醛酸醛酸酯（GX）途径分解为D-葡萄糖醛酸。 MIOX引发的GX途径导致扰动的NADPH：NADP+和NAD+：NADH比率在4个步骤[图。 1]，类似于多元途径；表明其激活将诱导氧化剂和低氧应激最终导致DN中ECM蛋白质和拟南芥的损伤的合成增加[图。 2]。扰动的NAD+/NADH比也会导致NAD+的耗竭，这是由于NAD依赖性脱乙酰基酶的活性而受到损害。 Sirutins的靶标包括FOXO家族转录因子和转录共激活因子PGC-1，可调节线粒体生物发生和各种抗氧化剂基因。使用这些扰动，管状细胞可能会经历能量应激和凋亡。我们发布的（JBC 2011，AJP 2010）和初步数据表明，ROS是在GX途径中生成的，进而增加Miox的转录，从而建立了ROS的环状生成。数据还表明GX途径存在于肾脏中[图。 4]，氧化应激发生在DN患者的管状区室中[图。 3]。同样，高葡萄糖中的Miox过表达会导致ECM蛋白的突出合成[图。 10]。通过这种背景并实现提案的目标，提出了以下3个特定目标。目的是描述机制，在高葡萄糖存在下，在管状细胞中Miox过表达导致氧化剂应激，线粒体功能障碍和ECM合成的强调。 NADPH的状态：NADP+＆NAD+：NADH比率，GSH，NOX4，PKC，TGF-，SIRTS，转录因子，线粒体动力学以及促和抗凋亡基因。特定的抑制剂/激活剂将用于测试Miox效应的特异性。 AIM II是在体内诱导的GX途径，氧化还原不平衡和下游信号传导事件的特征，从而导致SIRT和线粒体功能障碍，细胞凋亡和Tubo Interstitial纤维化。将使用具有STZ诱导的糖尿病的CD1小鼠和用Akita小鼠过度表达的Miox Cross的小鼠。 AIM III是确定Miox基因缺失是否导致肾功能障碍的改善并进展为STZ诱导的糖尿病（+/-）小鼠中的STZ诱导的糖尿病以及突变无效的小鼠（ - - - ）小鼠与Akita小鼠交叉杂交时。可以预料，GX SIRT途径的表征将有助于制定新型的治疗策略，以减速DN中的小管互相损伤。