Factors that modify insulin action

改变胰岛素作用的因素

基本信息

批准号：
7996761
负责人：
MARIA G BUSE
金额：
$ 9.52万
依托单位：
MEDICAL UNIVERSITY OF SOUTH CAROLINA
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-01-01 至 2010-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7996761
关键词：
1-Phosphatidylinositol 3-Kinase Accounting Actins Address Adenoviruses Adipocytes Affect Alanine Animal Model Binding Blood Vessels Cells Chronic Complications of Diabetes Mellitus Data Development Diabetes Mellitus Disease Distal Dose Enzymes Epidemic Event Fatty acid glycerol esters Fructose Functional disorder GRB2 gene Glucocorticoids Glucose Glutamine Goals Hepatic Hexosamines Human Hyperglycemia In Vitro Insulin Insulin Receptor Insulin Resistance Insulin-Dependent Diabetes Mellitus Insulin-Like Growth Factor I Insulin-Like-Growth Factor I Receptor Knock-out Lead Leptin Liver MAPK8 gene Mass Spectrum Analysis Mediating Metabolic syndrome Metabolism Modeling Modification Modus Molecular Target Morbidity - disease rate Mus Muscle Fibers Mutate Non-Insulin-Dependent Diabetes Mellitus Nonesterified Fatty Acids Nutrient O-GlcNAc transferase Obesity PTEN gene PTEN protein PTPN11 gene Pathway interactions Patients Phosphorylation Phosphorylation Site Play Polycystic Ovary Syndrome Post-Translational Protein Processing Prevalence Process Production Protein phosphatase Proteins Rattus Receptor Signaling Role Septicemia Signal Transduction Sirolimus Site Testing Time Toxic effect UDP-glucosamine Uremia base design diabetic patient glucose transport human FRAP1 protein improved in vivo insight insulin signaling insulin tolerance interest knock-down liver metabolism mortality mutant new therapeutic target novel overexpression phosphatidylinositol 3,4,5-triphosphate prevent protein expression public health relevance research study response small hairpin RNA

项目摘要

DESCRIPTION (provided by applicant): "Glucose toxicity" accounts for insulin resistance in patients with uncontrolled type 1 diabetes and contributes to it in type 2 diabetes. It contributes to the vascular complications, the major causes of morbidity and mortality in diabetic patients. Sustained exposure of cells to high glucose increases flux via the hexosamine synthesis pathway, enhancing the production of UDP-N-acetyl glucosamine (UDP-GlcNAc), the substrate of O-GlcNAc transferase (OGT). OGT catalyzes the reversible, single addition of O-GlcNAc to specific Ser/Thr residues. O-GlcNAcylation and O-phosphorylation are often reciprocal. We have recently identified, for the first time, four sites of O-GlcNAcylation on IRS-1 (as well as 11 novel Ser/Thr phosphorylation sites) by mass spectrometry. Preliminary data suggest that O-GlcNAc may affect IRS-1 signal transduction. Our major objective in Spec. Aim 1 is to firmly establish whether the O-GlcNAc modification alters IRS-1 signaling. In in vitro studies Ser will be mutated to Ala at the four O-GlcNAc sites, singly and in combination, wild type and mutated IRS-1 will be expressed in HepG2 cells and in intact liver via adenovirus, and their interactions with IRS-1 binding partners in response to insulin or to IGF-1 studied. In in vivo studies endogenous mouse IRS-1 will be knocked out with shRNA adenovirus and substituted with wild type or mutant IRS-1-expressing adenovirus. The effect of these manipulations on glucose and insulin tolerance tests and the expression of hepatic gluconeogenic enzymes will be studied. In Spec Aim 2 studies will be continued in a model of high glucose/ low dose insulin-induced insulin resistance of glucose transport and Akt activation in 3T3-L1 adipocytes. Insulin signaling to PI(3)K is largely maintained, but Akt activation is markedly impaired. Recent data indicate that PTEN protein expression is increased and insulin stimulated PtdIns(3,4,5)P3 is diminished. Stimulation of PTEN expression is inhibited by rapamycin. mTORC-1 activation clearly plays a role, cPKC may contribute, but JNK does not. The mechanism of enhanced PTEN expression, mTORC-1 action and the role of cPKC will be investigated. Several mechanisms which may synergize with or be mediated by mTOR will be addressed, including dysregulation of actin dynamics and possible activation of a phosphoprotein phosphatase(s). The analysis of the modus operandi in this model will be contrasted with the insulin resistance of glucose transport elicited by exposing cells to FFA. Insights gained from this model will be applied to L-6 myotubes and to intact rats made insulin resistant by chronic hyperglycemia. Understanding how different excess nutrients modify insulin's signaling may lead to the rational development of novel therapeutic targets.

描述（由申请人提供）：“葡萄糖毒性”导致未受控制的 1 型糖尿病患者出现胰岛素抵抗，并导致 2 型糖尿病患者出现胰岛素抵抗。它导致血管并发症，这是糖尿病患者发病和死亡的主要原因。细胞持续暴露于高葡萄糖会增加己糖胺合成途径的通量，从而增强 UDP-N-乙酰氨基葡萄糖 (UDP-GlcNAc) 的产生，UDP-GlcNAc 是 O-GlcNAc 转移酶 (OGT) 的底物。 OGT 催化 O-GlcNAc 可逆地单次添加到特定的 Ser/Thr 残基上。 O-GlcNAc 酰化和 O-磷酸化通常是相互的。我们最近首次确定了四个地点通过质谱法检测 IRS-1（以及 11 个新的 Ser/Thr 磷酸化位点）上的 O-GlcNAcylation。初步数据表明 O-GlcNAc 可能影响 IRS-1 信号转导。我们在规格方面的主要目标。目标 1 是确定 O-GlcNAc 修饰是否会改变 IRS-1 信号传导。在体外研究中，Ser 将在四个 O-GlcNAc 位点单独或组合突变为 Ala，野生型和突变型 IRS-1 将通过腺病毒在 HepG2 细胞和完整肝脏中表达，以及它们与 IRS-1 的相互作用结合伙伴对胰岛素或所研究的 IGF-1 作出反应。在体内研究中，内源性小鼠IRS-1将被shRNA腺病毒敲除并用野生型或突变体取代表达IRS-1的腺病毒。将研究这些操作对葡萄糖和胰岛素耐量测试以及肝糖异生酶表达的影响。在 Spec Aim 2 中，研究将在高葡萄糖/低剂量胰岛素诱导的 3T3-L1 脂肪细胞中葡萄糖转运和 Akt 激活的胰岛素抵抗模型中继续进行。胰岛素至 PI(3)K 的信号转导很大程度上得以维持，但 Akt 激活明显受损。最近的数据表明，PTEN 蛋白表达增加，胰岛素刺激的 PtdIns(3,4,5)P3 减少。雷帕霉素可抑制 PTEN 表达的刺激。 mTORC-1 激活显然发挥了作用，cPKC 可能有所贡献，但 JNK 没有。将研究增强 PTEN 表达的机制、mTORC-1 作用和 cPKC 的作用。将讨论可能与 mTOR 协同作用或由 mTOR 介导的几种机制，包括肌动蛋白动力学失调和磷蛋白磷酸酶可能的激活。该模型中操作方式的分析将与将细胞暴露于 FFA 引起的葡萄糖转运的胰岛素抵抗进行对比。从该模型中获得的见解将应用于 L-6 肌管和因慢性高血糖而产生胰岛素抵抗的完整大鼠。了解不同的过量营养素如何改变胰岛素信号可能有助于合理开发新的治疗靶点。