REGULATION OF NEURONAL MITOCHONDRIAL MRNA METABOLISM

神经元线粒体 mRNA 代谢的调节

• 批准号: 2859720
• 负责人: KRISH CHANDRASEKARAN
• 金额: $ 7.42万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-04-01 至 2001-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2859720
• 关键词: Alzheimer's disease; Animalia; aging; apoptosis; excitatory aminoacid; gene induction /repression; intracellular; messenger RNA; mitochondria; neuroregulation; northern blottings; nucleic acid metabolism; oxidative stress; sodium; stroke; tissue /cell culture

Mechanisms regulating metabolism of mitochondrial DNA-encoded mRNA (mtmRNA) for enzyme complexes of oxidative phosphorylation system are not well understood although evidence indicates that alterations in mitochondrial energy metabolism likely to contribute to the pathophysiology of neurodegenerative diseases. We have observed that elevation of intracellular sodium ([Na+]i) markedly decreases levels of mtmRNA in cultured neurons. This was unexpected since high [Na+]i increases energy demand which normally up-regulates mitochondrial metabolism. Long-term Goal: To understand the mechanism(s) of Na+-dependent regulation of mitochondrial gene expression and to determine how this may contribute to selective neuronal vulnerability to delayed neuronal death in stroke and neurodegenerative disorders. Specific Aim: Test the hypothesis that inhibition of mitochondrial gene expression by high [Na+]i is elicited by an excitotoxic insult and that it contributes to delayed neuronal death. Rationale: High [Na+]i following exposure of primary neuronal cultures to excitotoxic levels of glutamate inhibits mitochondrial gene expression, compromises cellular energy metabolism, affects electron transport-dependent mitochondrial activities (e.g., ATP synthesis, [Ca2+]i buffering free radical generation and sensitivity to Ca2+-induced release of cytochrome c: and increases neuronal vulnerability to both necrotic and apoptotic cell death. Approach: Levels of mitochondrial mRNA, respective protein subunits, associated enzyme activity (i.e., cytochrome oxidase activity) and mitochondrial respiration will be monitored in primary neuronal cultures after exposure to excitotoxic levels of glutamate and compared to cellular ATP levels and markers of neuronal death over 24 hours in the absence and presence of a delayed, secondary glutamate exposure. Significance: This project examines a new mechanism by which elevated [Na+]i contribute to delayed cell death. An understanding of this mechanism could lead to the development of novel neuroprotective interventions.

线粒体DNA编码的mRNA（mtmRNA）的氧化磷酸化系统的酶复合物的代谢调节机制还没有得到很好的理解，虽然有证据表明，线粒体能量代谢的改变可能有助于神经退行性疾病的病理生理。我们已经观察到，细胞内钠（[Na+]i）的升高显着降低mtmRNA的水平在培养的神经元。 这是出乎意料的，因为高[Na+]i增加能量需求，这通常上调线粒体代谢。 长期目标：了解线粒体基因表达的Na+依赖性调节机制，并确定这可能如何导致卒中和神经退行性疾病中迟发性神经元死亡的选择性神经元脆弱性。具体目标：检验高[Na+]i对线粒体基因表达的抑制是由兴奋性毒性损伤引起的，并导致迟发性神经元死亡的假设。 基本原理：原代神经元培养物暴露于兴奋毒性水平的谷氨酸后的高[Na+]i抑制线粒体基因表达，损害细胞能量代谢，影响电子转运依赖性线粒体活性（例如，ATP合成、[Ca2+]i缓冲自由基生成和对Ca2+诱导的细胞色素c释放的敏感性：并增加神经元对坏死和凋亡细胞死亡的脆弱性。 方法：线粒体mRNA、相应蛋白质亚基、相关酶活性（即，在暴露于兴奋性毒性水平的谷氨酸后，在原代神经元培养物中监测细胞内ATP水平（细胞色素氧化酶活性）和线粒体呼吸，并在不存在和存在延迟的二次谷氨酸暴露的情况下，在24小时内与细胞ATP水平和神经元死亡的标志物进行比较。意义：本项目研究了一种新的机制，通过这种机制，[Na+]i升高有助于延迟细胞死亡。 对这一机制的理解可能会导致新的神经保护干预措施的发展。