CHROMIUM ENHANCEMENT OF INSULIN SIGNALING

铬增强胰岛素信号传导

• 批准号: 6657382
• 负责人: DAVID L. BRAUTIGAN
• 金额: $ 22.05万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-15 至 2007-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6657382
• 关键词: alternative medicine; biological signal transduction; chemical binding; chromium; diabetes mellitus therapy; dietary supplements; dietary trace element; insulin; insulin receptor; noninsulin dependent diabetes mellitus; nutrient interaction; nutrition related tag; phosphorylation; protein tyrosine phosphatase; recombinant proteins; site directed mutagenesis; tissue /cell culture; alternative medicine; biological signal transduction; chemical binding; chromium; diabetes mellitus therapy; dietary supplements; dietary trace element; insulin; insulin receptor; noninsulin dependent diabetes mellitus; nutrient interaction; nutrition related tag; phosphorylation; protein tyrosine phosphatase; recombinant proteins; site directed mutagenesis; tissue /cell culture

DESCRIPTION (provided by applicant): Chromium is a micronutrient that potentiates the action of insulin and is an essential component of "glucose tolerance factor" discovered over 40 years ago. Chromium could have beneficial effects for the >15 million type-2 diabetics in the USA, and many Americans already take Cr (III) as a daily dietary supplement, alone or in multivitamin formulations. Nonetheless, there is scant information and continuing controversy regarding the biology of Cr (III), including uptake, bioavailability, target of action and even whether the metal ion itself or some organo-metallic complex is the bioactive species. The goal of this project is to define the biochemical basis for chromium enhancement of insulin action. In preliminary studies various organic and inorganic forms of Cr (III) were found to be equally efficacious in potentiating initial signaling events triggered by insulin. Chromium added at nanomolar concentrations to intact living cells in culture increased insulin-stimulated Tyr phosphorylation at sub-optimal doses of insulin. The effect was attributed to impaired insulin receptor (IR) dephosphorylation, assayed by addition of chromium to purified membranes. This project will extend these studies to test the hypothesis that Cr (III) inhibits the dephosphorylation of the activated IR by protein Tyr phosphatases (PTP). This could occur by interaction of the Cr (III) either with PTP, blocking the enzyme activity by interacting with an active site cysteine, or with the substrate, the Tyr phosphorylated IR, protecting it from dephosphorylation. Experiments will use dephosphorylation assays to identify the target protein (PTP or IR). Analysis of reaction products will show whether chromium action is selective for different Tyr phosphorylation sites in the IR, which would enhance specific downstream signaling pathways. Structural determinants for interaction with chromium will be determined by mutagenesis and Cr(III) binding assays with recombinant target protein. The results will provide new knowledge of the molecular actions of Cr (III), provide a basis for understanding the biological effects of dietary chromium and open new opportunities for interventions to combat type-2 diabetes.

描述（由申请人提供）：铬是一种增强胰岛素作用的微量营养素，是40年前发现的“葡萄糖耐量因子”的重要组成部分。铬对美国> 1500万型糖尿病患者可能会产生有益的影响，许多美国人已经将CR（III）作为日常饮食补充剂，单独或多种维生素制剂。尽管如此，关于CR（III）的生物学存在很少的信息，包括摄取，生物利用度，作用目标，甚至金属离子本身或某些有机金属络合物是生物活性物种。该项目的目的是确定胰岛素作用增强铬的生化基础。在初步研究中，发现各种有机和无机形式的Cr（III）在增强胰岛素触发的初始信号事件方面同样有效。在培养物中，以纳摩尔浓度添加到完整活细胞中的铬增加了胰岛素刺激的tyr磷酸化在亚最佳剂量的胰岛素下。该作用归因于胰岛素受体（IR）去磷酸化受损，并通过在纯化的膜中添加铬来测定。该项目将扩展这些研究，以检验CR（III）抑制蛋白质Tyr磷酸酶（PTP）激活IR磷酸化的假设。这可以通过CR（III）与PTP的相互作用来发生，从而通过与活性位点半胱氨酸或与底物相互作用，或与底物，Tyr磷酸化的IR相互作用，从而保护其免受去磷酸化的影响。实验将使用去磷酸化测定法来识别靶蛋白（PTP或IR）。反应产物的分析将显示铬作用是否针对IR中不同的Tyr磷酸化位点有选择性，这将增强特定的下游信号通路。与铬相互作用的结构决定因素将由诱变和与重组靶蛋白的CR（III）结合测定确定。结果将为CR（III）的分子作用提供新的知识，为理解饮食铬的生物学作用提供了一个基础，并开放了开放的干预措施来对抗2型糖尿病。