Circadian regulation of mitochondrial RNA polyadenylation

线粒体 RNA 多腺苷酸化的昼夜节律调节

基本信息

批准号：
8747363
负责人：
Carla B. Green
金额：
$ 30.61万
依托单位：
UT SOUTHWESTERN MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2014
资助国家：
美国
起止时间：
2014-07-10 至 2018-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8747363
关键词：
Address Affect Behavior Cell Respiration Cell physiology Cells Cellular Structures Circadian Rhythms Complex Cytochrome-c Oxidase Deficiency Cytoplasm Data Diabetes Mellitus Diet Disease Drug Metabolic Detoxication Eating Electron Transport Energy-Generating Resources Enzymes Feedback Functional disorder Genes Heart Diseases Human Hypertrophic Cardiomyopathy Initiator Codon Intake Kinetics Lactic Acidosis Leigh Disease Length Link Liver diseases Maintenance Messenger RNA Metabolic Metabolism Mitochondria Mitochondrial Proteins Mitochondrial RNA Molecular Mus Mutation Nerve Degeneration Neurodegenerative Disorders Nutrient Obesity Oxidative Phosphorylation Oxygen Consumption Periodicity Physiology Poly(A) Tail Polyadenylation Process Production Proteins Reaction Reactive Oxygen Species Recovery Regulation Resistance Respiration Role Scanning Signal Transduction System Tail Testing Time Translation Initiation Translations Work base circadian pacemaker complex IV cytochrome c oxidase design insight mitochondrial messenger RNA mouse model nocturnin novel nuclease programs protein complex public health relevance

项目摘要

DESCRIPTION (provided by applicant): Circadian clocks are internal timekeeping mechanisms that temporally coordinate many aspects of behavior and physiology with the diurnal cycle. These clocks control thousands of genes that drive many critical processes within the cell, including many metabolic processes. Furthermore, nutrient intake and many metabolic processes also feedback to regulate the central clock mechanism and disruption of the clock results in broad metabolic dysfunction. An important role of the clock may be to temporally coordinate metabolic programs throughout the circadian cycle to increase efficiency and avoid futile reactions. In this proposal, we provide evidence that expands the influence of the clock to yet another critical metabolic component of the cell - the oxidative phosphorylation system of the mitochondrion. We present new evidence demonstrating that the circadian protein Nocturnin is regulating the activity of cytochrome c oxidase (Complex IV) of the electron transport chain. Nocturnin encodes a deadenylase, an enzyme responsible for removing poly A tails from mRNAs, and in this proposal we present data that shows that Nocturnin works in the mitochondria (in addition to its known role in the cytoplasm) to post-transcriptionally control one of the mRNAs that is critical for Complex IV assembly and function. Based on these data, we propose three specific aims designed to test the general hypothesis that the circadian clock regulates oxidative phosphorylation through rhythmic Nocturnin deadenylation of mitochondria-encoded mRNAs. In the first specific aim, we will examine how Nocturnin intracellular localization is regulated and test whether alternative translation initiation regulates whether or not a mitochondrial targeting signal is added to the Nocturnin protein. In the second aim, we will examine the mechanism by which Nocturnin regulates Complex IV activity and mitochondrial oxidative phosphorylation. We will test whether Nocturnin is part of a "machine" that dynamically regulates mitochondrial mRNA poly A tail length and test whether this results in altered translation of the target mRNA. Finally, in the third aim, we will test whether these processes are directly regulated by the circadian clock and will determine the kinetics of Complex IV assembly at different times of day. Furthermore, we will test whether Nocturnin' s rhythmicity is important for proper functioning of the oxidative phosphorylation system using an inducible mouse model that expresses Nocturnin in a non-rhythmic manner. These proposed studies will uncover the mechanism behind this new and exciting role, for the circadian system control of the ATP generating system of the cell. One in 5000 humans have mutations that affect Complex IV assembly and activity resulting in severe disease, including encephalomyopathies, neurodegenerative Leigh syndrome, hypertrophic cardiomyopathies, and fatal lactic acidosis. Therefore, understanding how this system is modulated is of critical importance.

描述（由申请人提供）：昼夜节律钟是内部计时机制，可在时间上协调行为和生理学的许多方面与昼夜周期。这些时钟控制着数千个基因，这些基因驱动细胞内的许多关键过程，包括许多代谢过程。此外，营养摄入和许多代谢过程也会反馈调节中央生物钟机制，而生物钟的破坏会导致广泛的代谢功能障碍。时钟的一个重要作用可能是在整个昼夜节律周期中临时协调代谢程序，以提高效率并避免无用的反应。在这项提议中，我们提供的证据将时钟的影响扩展到细胞的另一个关键代谢成分——线粒体的氧化磷酸化系统。我们提出了新的证据，证明昼夜节律蛋白 Nocturnin 正在调节电子传递链的细胞色素 C 氧化酶（复合体 IV）的活性。 Nocturnin 编码去腺苷酸酶，这是一种负责从 mRNA 中去除多聚 A 尾的酶，在本提案中，我们提供的数据表明，Nocturnin 在线粒体中发挥作用（除了其在细胞质中的已知作用之外），以在转录后控制一个对复合物 IV 组装和功能至关重要的 mRNA。基于这些数据，我们提出了三个具体目标，旨在测试生物钟通过线粒体编码 mRNA 的节律性 Nocturnin 去腺苷化来调节氧化磷酸化的一般假设。在第一个具体目标中，我们将研究 Nocturnin 细胞内定位是如何调节的，并测试替代翻译起始是否调节是否将线粒体靶向信号添加到 Nocturnin 蛋白。在第二个目标中，我们将研究 Nocturnin 调节复合物 IV 活性和线粒体氧化磷酸化的机制。我们将测试 Nocturnin 是否是动态调节线粒体 mRNA 聚 A 尾长度的“机器”的一部分，并测试这是否会导致目标 mRNA 的翻译发生改变。最后，在第三个目标中，我们将测试这些过程是否是直接受生物钟调节，并将决定复杂 IV 在一天中不同时间组装的动力学。此外，我们将使用以非节律方式表达Nocturnin的诱导型小鼠模型来测试Nocturnin的节律性对于氧化磷酸化系统的正常功能是否重要。这些拟议的研究将揭示这种令人兴奋的新作用背后的机制，即细胞 ATP 生成系统的昼夜节律系统控制。五千分之一的人患有影响复合体 IV 组装和活性的突变，导致严重疾病，包括脑肌病、神经退行性利氏综合征、肥厚性心肌病和致命的乳酸性酸中毒。因此，了解该系统的调节方式至关重要。