Regulation of substrate-linked mitochondrial ROS generation

描述（由申请人提供）： 葡萄糖利用率影响细胞生长、增殖和存活。这些效应中的许多似乎取决于葡萄糖代谢，特别是线粒体通量的底物水平控制。胰腺β细胞中的葡萄糖感知通过线粒体氧化磷酸化与胰岛素分泌偶联，对细胞能荷有直接影响。多种细胞类型（包括内皮细胞和胰腺β细胞）长期暴露于高葡萄糖浓度导致底物供应与氧化磷酸化的偶联效率低下，通过将还原当量转移至分子氧的单电子还原而形成超氧化物自由基。这个应用程序解决了关于细胞如何响应正能量平衡的关键问题。使用内皮细胞和胰岛细胞系作为原型细胞谱系，我们将表征细胞和线粒体对营养源葡萄糖的可用性的反应，超过代谢要求。具体地，我们已经发现，在25 mM葡萄糖中孵育原代内皮细胞诱导c-myc转录、NF-κ B促炎途径的激活和PI 3-K/Akt信号转导的下调。这些途径中的每一个都与线粒体代谢和氧化还原稳态有关。提出了以下具体目标：1。为了检验假设葡萄糖刺激的氧化应激依赖于NRF- 1依赖性线粒体基因表达的c-myc反式激活。2.为了验证由NF-κ B转录因子诱导的Bcl-xL通过调节线粒体氧化还原载体之间的平衡来减少葡萄糖刺激的氧化应激的假设。从这些研究中获得的见解将帮助我们了解高血糖是如何发生的。这些信息对于设计有效的预防和治疗美国不断增长的糖尿病患者的终末器官损伤非常重要。

DESCRIPTION (provided by applicant): Glucose availability affects cell growth, proliferation and survival. Many of these effects appear to depend on glucose metabolism, and in particular, substrate level control of mitochondrial flux. Glucose sensing in pancreatic beta cells is coupled to insulin secretion via mitochondrial oxidative phosphorylation with direct effects on cellular energy charge. Longer term exposure of multiple cell types, including endothelium and pancreatic beta cells, to high glucose concentrations results in inefficient coupling of substrate supply to oxidative phosphorylation, with formation of superoxide radicals by diversion of reducing equivalents to single electron reduction of molecular oxygen. This application addresses key questions about how cells respond to positive energy balance. Using endothelial cells and islet cell lines as prototypic cell lineages, we will characterize cellular and mitochondrial responses to the availability of a nutrient source, glucose, in excess of metabolic requirements. Specifically, we have found that incubation of primary endothelial cells in 25 mM glucose induces c-myc transcription, activation of NF-KB pro-inflammatory pathways and downregulation of PI3-K/Akt signaling. Each of these pathways is relevant to mitochondrial metabolism and redox homeostasis. The following specific aims are proposed: 1. To test the hypothesis glucose-stimulated oxidative stress is dependent on c-myc transactivation of NRF- 1-dependent mitochondrial gene expression. 2. To test the hypothesis that Bcl-xL, induced by NF-kB transcription factors, reduces glucose-stimulated oxidative stress by modulating the equilibrium between mitochondrial redox carriers. Insights gained from these studies will help us understand how hyperglycemia This information will be important for designing effective prevention and treatment for end organ damage for the growing population in the United States with diabetes.