Role of SGLT3 in diabetes-mediated increased renal sodium reabsorption

SGLT3 在糖尿病介导的肾钠重吸收增加中的作用

• 批准号: 7898291
• 负责人: NILOOFAR M TABATABAI
• 金额: $ 28.61万
• 依托单位: MEDICAL COLLEGE OF WISCONSIN
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-06-15 至 2015-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7898291
• 关键词: Affinity; Age; Agonist; Amino Acid Sequence; Amino Acid Sequence Homology; Animal Model; Animals; Antibodies; Apical; Binding; Blood Pressure; Brain; C57BL/6 Mouse; COS-7 Cell; Cadmium; Carrier Proteins; Cell Line; Cell membrane; Cells; Chronic; Colon; Confocal Microscopy; Custom; Data; Development; Diabetes Mellitus; Diabetic Nephropathy; Diabetic mouse; End stage renal failure; Epithelial Cells; Exposure to; Family; Family suidae; Fluorescence; Fluorescent Antibody Technique; Genes; Glucose; Glucose Transporter; Goals; Health; Human; Hyperglycemia; Hypertension; Immunoblotting; In Vitro; Intestines; Investigation; Ion Channel; Ions; Kidney; Knock-out; Knowledge; Malignant Epithelial Cell; Measures; Mediating; Mediator of activation protein; Membrane Protein Traffic; Messenger RNA; Microscopy; Modeling; Mouse Strains; Mus; Na(+)-K(+)-Exchanging ATPase; Non-Insulin-Dependent Diabetes Mellitus; Oocytes; Ovary; Phlorhizin; Physiological Processes; Play; Property; Protein Isoforms; Proteins; Proximal Kidney Tubules; Rattus; Renal carcinoma; Research Design; Risk Factors; Role; Secondary to; Side; Skeletal Muscle; Small Intestines; Sodium; Sodium Chloride; Techniques; Testing; Time; Tissues; United States; Water; Xenopus laevis; Xenopus oocyte; absorption; base; design; diabetic; diabetic patient; glucose analog; glucose transport; glucose uptake; in vivo; kidney cell; knock-down; mouse model; non-diabetic; novel; public health relevance; response; small hairpin RNA; solute; sugar; uptake; young adult

DESCRIPTION (provided by applicant): Diabetic nephropathy is the leading cause of end-stage renal disease in the United States. Hyperglycemia has been recognized as a major risk factor in the development and progression of diabetic nephropathy. Hyperglycemia-induced increase in proximal tubule (PT) Na+ retention has been shown in diabetic patients and in animal models of diabetes. This enhanced Na+ reabsorption may play a role in the development of hypertension, which is an additional contributing factor in the development of diabetic nephropathy and the end stage renal disease. A role for a PT sodium-glucose cotransporter (SGLT) in hyperglycemia-induced increased sodium retention has been suggested but this transporter has not yet been identified. Kidney expresses SGLT1 and SGLT2 on the apical side of the PT cells. These proteins play crucial roles in sodium-dependent uptake of glucose from the glomerular filtrate. SGLT3 mRNA has been found in the human kidney carcinoma cells and in the pig kidney. When over-expressed in Xenopus oocytes, human SGLT3 did not transport glucose but in response to glucose, it mediated inward flux of sodium. Mouse has two genes encoding SGLT3a and 3b and we have shown that their mRNAs were expressed in the kidney and in the cultured kidney cells from mouse. We also showed while mRNA levels of SGLT3s in cultured mouse primary kidney cells exposed to cadmium were several folds higher than in their levels in untreated cells, the sodium-dependent uptake of glucose in Cd-treated cells had decreased supporting that SGLT3 is not a glucose transporter. Based on the above and additional preliminary studies with the potent agonist of SGLT3, deoxynojirimycin (DNJ), we hypothesize that kidney SGLT3 serves as a novel glucose-stimulated Na+ transporter in the PT that may play role in hyperglycemia-induced Na+ retention in diabetes. To test our hypothesis, we propose: (1) To localize the SGLT3 protein in human and mouse kidneys, (2) To determine the role of SGLT3 in glucose-mediated Na+ uptake in PT cells in vitro, (3) To determine the role of SGLT3 in hyperglycemia-mediated PT Na+ reabsorption in vivo. The proposed in vitro and in vivo studies are designed to investigate the role of SGLT3 as a novel glucose-stimulated Na+ transporter that may play role in the enhanced Na+ reabsorption in diabetes. PUBLIC HEALTH RELEVANCE: One of the major adverse health effects of diabetes is damage to the kidneys. Increased kidney salt reabsorption in diabetes may play a role in the development of high blood pressure, which in turn can cause damage to the kidneys. The mechanism of diabetes-induced increased salt reabsorption is not known. We have evidence that a novel sodium transporter may be a mediator. The goal of this study is to show that human kidneys express this protein and also to show that glucose stimulates sodium uptake by this transporter. This study is designed to identify the mechanism for the enhanced salt retention in diabetes.

描述（由申请人提供）：糖尿病性肾病是美国终末期肾脏疾病的主要原因。高血糖被认为是糖尿病肾病发育和进展的主要危险因素。高血糖诱导的近端小管（PT）Na+保留率的增加已在糖尿病患者和糖尿病的动物模型中显示。这种增强的Na+重吸收可能在高血压的发展中发挥作用，这是糖尿病肾病和终阶段肾脏疾病发展的另一个促成因素。已经提出了PT钠 - 葡萄糖共转运蛋白（SGLT）在高血糖诱导的增加钠保留率中的作用，但尚未鉴定出该转运蛋白。肾脏在PT细胞的顶端表达SGLT1和SGLT2。这些蛋白质在肾小球滤液的葡萄糖摄取中起着至关重要的作用。在人肾癌细胞和猪肾中发现了SGLT3 mRNA。当在异武卵母细胞中过表达时，人类sglt3不会转运葡萄糖，而是对葡萄糖的响应，它介导了钠的向内通量。小鼠有两个编码SGLT3A和3B的基因，我们已经证明它们的mRNA在肾脏和来自小鼠培养的肾细胞中表达。我们还表明，在暴露于镉的小鼠原代肾细胞中的mRNA水平比未经处理的细胞中的水平高几倍，而CD处理的细胞中钠依赖性葡萄糖的摄取降低了sglt3不是葡萄糖转运蛋白。基于上述和对SGLT3，脱氧二吉利霉素（DNJ）的有效激动剂的其他初步研究，我们假设肾脏SGLT3在PT中可以作为一种新型的葡萄糖刺激的Na+ Transporter，在PT中可能在高血糖诱导的NA+ diabetes中发挥作用。为了检验我们的假设，我们提出：（1）在人和小鼠肾脏中定位SGLT3蛋白，（2）确定SGLT3在PT细胞中葡萄糖介导的Na+摄取在体外的Na+摄取的作用（3），以确定SGLT3在高血糖介导的PT Na+ Reauption中SGLT3在高血糖介导的PT Na+ Reauption中的作用。所提出的体外和体内研究旨在研究SGLT3作为一种新型葡萄糖刺激的Na+转运蛋白的作用，该转运蛋白可能在糖尿病中增强的Na+重吸收中起作用。 公共卫生相关性：糖尿病的主要不良健康影响之一是对肾脏的损害。糖尿病中肾脏盐的重吸收增加可能在高血压发展中起作用，进而会对肾脏造成损害。尚不清楚糖尿病引起的盐分吸收的机理。我们有证据表明，新型钠转运蛋白可能是调解人。这项研究的目的是表明人肾脏表达了这种蛋白质，并且还表明葡萄糖刺激该转运蛋白的钠摄取。这项研究旨在确定糖尿病中盐含量增强的机制。