Factors that modify insulin action

改变胰岛素作用的因素

• 批准号: 6728272
• 负责人: MARIA G BUSE
• 金额: $ 25.46万
• 依托单位: MEDICAL UNIVERSITY OF SOUTH CAROLINA
• 依托单位国家: 美国
• 财政年份: 1978
• 资助国家: 美国
• 起止时间: 1978-05-01 至 2007-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6728272
• 关键词: 3T3 cells; SDS polyacrylamide gel electrophoresis; acylation; adipocytes; amidophosphoribosyltransferase; carbohydrate biosynthesis; enzyme activity; genetically modified animals; glucose; glucose transport; glucose transporter; green fluorescent proteins; hexosamines; high performance liquid chromatography; immunoprecipitation; insulin; insulin receptor; insulin sensitivity /resistance; intracellular transport; laboratory mouse; mass spectrometry; noninsulin dependent diabetes mellitus; pancreatic islet function; striated muscles; two dimensional gel electrophoresis; western blottings

DESCRIPTION (provided by applicant): "Glucose toxicity" accounts for insulin resistance in uncontrolled Type 1 diabetes and contributes to it in Type 2 diabetes. In 3T3-L1 adipocytes, preincubation in high glucose + 0.6 nM insulin synergistically down-regulate insulin stimulation of glucose transport and Akt/PKB activation distal to phosphatidyl inositol-3- kinase (PI(3)K) activation. The hexosamine synthesis pathway has been implicated in insulin resistance; its major product is UDP-N-acetylglucosamine (UDP-GIcNAc), the substrate of O-GIcNAc-transferase (OGT). OGT catalyzes the addition of single O-GIcNAc to specific Ser/Thr residues. O-GIcNAcylation and O-phosphorylation are often reciprocal. Chronic increased glucose flux enhances protein O-GIcNAcylation in cells and in muscle, in vivo. The role of enhanced O-GIcNAcylation in insulin resistance will be studied in 3T3-L1 adipocytes, L-6 myotubes and in skeletal muscle of insulin-resistant mouse models. Glucose/insulin-responsive O-GIcNAcylated proteins will be identified by mass spectrometry combined with immunological methods. Of special interest are proteins involved in GLUT4 trafficking. O-GIcNAcylation site(s) will be identified and the functional significance of the modification evaluated. The effect of O-GIcNAc-ase overexpression will be studied to test whether preventing excessive O-GIcNAcylation mitigates or prevents glucose-induced insulin resistance. Akt is a downstream target of PI(3)K involved in insulin's metabolic effects, including glucose transport. The mechanism of impaired Akt activation in glucose-induced insulin resistance will be studied. If insulin-stimulated 3-phosphoinositides at the plasma membrane (PM) are decreased, their dephosphorylation may be accelerated, e.g. by SHIP2 or PTEN, or PI(3)K may be mistargeted. If insulin normally stimulates 3-phosphoinositides at the PM in insulin-resistant cells, the activity of phosphoinositide dependent kinase-1 (PDK-1) or effects on Akt itself (e.g., accelerated dephosphorylation or protein interactions) will be examined. The possible role of altered O-GIcNAcylation in the identified defect(s) will be assessed. Defining mechanisms of insulin resistance may lead to the development of novel therapeutic targets.

描述（由申请人提供）：“葡萄糖毒性”是未受控制的1型糖尿病中胰岛素抵抗的说明，并在2型糖尿病中促成了胰岛素。在3T3-L1脂肪细胞中，高葡萄糖 + 0.6 nm胰岛素的预孵育协同下调胰岛素刺激葡萄糖转运的胰岛素刺激和Akt/PKB激活远端，磷脂酰肌醇-3-激酶（PI（3）K）激活。己胺的合成途径与胰岛素抵抗有关。它的主要产物是UDP-N-乙酰葡萄糖胺（UDP-GICNAC），O-GICNAC-转移酶（OGT）的底物。 OGT将单个O-GICNAC催化为特定的Ser/THR残基。 O-环元和O-磷酸化通常是相互的。慢性增加的葡萄糖通量可增强细胞和肌肉中的蛋白质O-环囊化。在3T3-L1脂肪细胞，L-6肌管和胰岛素耐药小鼠模型的骨骼肌中，将研究增强的O-核化在胰岛素抵抗中的作用。葡萄糖/胰岛素反应性O-胶囊蛋白将通过质谱和免疫学方法结合鉴定。特别感兴趣的是参与GLUT4运输的蛋白质。将确定O-磁囊化位点，并评估了修饰的功能意义。将研究O-GICNAC-ase过表达的作用，以测试防止过度的O-磁囊性减轻或防止葡萄糖诱导的胰岛素耐药性。 AKT是参与胰岛素代谢作用（包括葡萄糖转运）的PI（3）K的下游靶标。将研究葡萄糖诱导的胰岛素抵抗中AKT激活受损的机制。如果胰岛素刺激的3-磷酸肌醇在质膜（PM）的降低，则可以加速其去磷酸化，例如通过Ship2或Pten或Pi（3）K可能被误入。如果胰岛素通常在胰岛素耐药细胞中刺激PM的3-磷酸肌醇，则将检查磷酸肌醇依赖性激酶-1（PDK-1）的活性或对AKT本身的影响（例如，加速去磷酸化或蛋白质相互作用）。 O-Gicnacylation在确定的缺陷中的可能作用可能会评估。胰岛素抵抗的定义机制可能导致新的治疗靶标的发展。