Molecular mechanisms of mammalian circadian clock function

哺乳动物生物钟功能的分子机制

基本信息

批准号：
10458088
负责人：
Carla B. Green
金额：
$ 58.26万
依托单位：
UT SOUTHWESTERN MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2018
资助国家：
美国
起止时间：
2018-08-07 至 2023-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10458088
关键词：
ARNTL gene Automobile Driving Behavior Biochemistry Cardiovascular Diseases Cell physiology Cholesterol Homeostasis Circadian Dysregulation Circadian Rhythms Clock protein Crystallization Cytosol Data Diabetes Mellitus Exhibits Feedback Future Gene Expression Genes Genetic Genetic Transcription Health Human Jet Lag Syndrome Length Link Liver Malignant Neoplasms Mammals Mediator of activation protein Mental disorders Messenger RNA Metabolic Mitochondria Modality Modeling Molecular Mus Obesity Periodicity Physiology Poly(A) Tail Polyadenylation Post-Transcriptional Regulation Proteins Regulation Resistance Role Structure System Tail Time Translational Regulation Triglyceride Metabolism Work circadian circadian pacemaker complex data cryptochrome 1 cryptochrome 2 diet-induced obesity insight nocturnin protein expression shift work transcription factor

项目摘要

Abstract Circadian clocks throughout the body drive rhythmic expression of thousands of genes, resulting in rhythms in biochemistry, physiology and behavior. Disruption of circadian clocks through genetics or environmental perturbations such as jet lag or shift-work, can have profound negative consequences and has been linked to obesity, diabetes, cancer, cardiovascular disease and mental illness. Our work is focused generally on understanding the detailed molecular mechanisms of the mammalian circadian clock machinery and the mechanisms by which these clocks control rhythmic gene expression. According to the current model, the core part of this clock mechanism is a negative feedback loop whereby the transcription factor heterodimer CLOCK/BMAL1 drives transcription of the “clock” proteins PERIOD (PER) 1, PER 2, CRYPTOCHROME (CRY) 1 and CRY 2 which interact with each other to repress the activity of CLOCK/BMAL1, and thus their own synthesis. We have solved crystal structures for the CLOCK/BMAL1 and CRY2/PER2 complexes and these data have allowed the identification of evolutionarily conserved functional domains throughout the proteins and revealed additional insights into the mechanisms by which these proteins operate and set the circadian period. Over the next five years, we will expand on this information to determine the atomic details of how this clock keeps time. The roles of these core circadian clock transcription factors in driving rhythmic transcription is well-documented, but recent data have demonstrated that post-transcriptional control, although much less well understood, is also critical for normal rhythmic protein expression profiles. One type of post-transcriptional control is regulation of mRNA poly(A) tail length, which impacts the stability and translational regulation of mRNA. We have identified hundreds of mouse liver mRNAs that exhibit robust circadian rhythms in the length of their poly(A) tails. In many of these cases, the rhythmic tail lengths are the result of rhythmic cytoplasmic polyadenylation and deadenylation rhythms and many components of the cytoplasmic polyadenylation and deadenylation machinery are themselves under circadian control. Furthermore, the rhythmic poly(A) tails are closely correlated with the rhythmic protein expression. Therefore, the circadian clock regulates dynamic polyadenylation status of many mRNAs that can drive rhythmic protein expression independent of the steady-state levels of the message. Nocturnin is a robustly rhythmic protein that removes poly(A) tails from mRNAs. We have shown that loss of this gene in mice causes resistance to diet-induced obesity and altered rhythms in cholesterol and triglyceride metabolism, implicating it as an important circadian post-transcriptional mediator. Over the next five years, we will focus on identifying the mRNA substrates of Nocturnin both in the cytosol and in the mitochondria.

抽象的全身的昼夜节律时钟驱动着数千个基因的有节奏的表达，从而导致通过遗传学或行为扰乱生物钟。时差或轮班工作等环境干扰可能会产生深远的负面后果并且与肥胖、糖尿病、癌症、心血管疾病和精神疾病有关。工作主要集中于了解哺乳动物的详细分子机制生物钟机制以及这些生物钟控制节律基因的机制根据目前的模型，这个时钟机制的核心部分是负数。反馈环路，转录因子异二聚体 CLOCK/BMAL1 驱动 “时钟”蛋白 PERIOD (PER) 1、PER 2、CRYPTOCHROME (CRY) 1 和 CRY 2 与彼此抑制CLOCK/BMAL1的活性，从而它们自己的合成我们已经解决了。 CLOCK/BMAL1 和 CRY2/PER2 复合体的晶体结构，这些数据允许鉴定整个蛋白质中进化保守的功能域并揭示对这些蛋白质运作和设定昼夜节律的机制有更多的了解。在接下来的五年里，我们将扩展这些信息，以确定如何处理的原子细节这些核心生物钟转录因子在驱动节律方面发挥着作用。转录有详细记录，但最近的数据表明，转录后控制，尽管了解较少，但对于正常的节律蛋白表达谱也至关重要。转录后控制的一种类型是调节 mRNA 聚 (A) 尾长度，这会影响我们已经鉴定了数百种小鼠肝脏 mRNA。在许多情况下，它们的多聚（A）尾巴的长度表现出强大的昼夜节律。有节奏的尾长是有节奏的细胞质多腺苷酸化和去腺苷酸化的结果细胞质多腺苷酸化和去腺苷酸化机制的节律和许多组成部分此外，有节律的poly(A)尾部密切相关。因此，生物钟动态调节。许多 mRNA 的多腺苷酸化状态可以驱动有节奏的蛋白质表达，与 Nocturnin 是一种强大的节律蛋白，可去除多聚 (A) 尾部。我们已经证明，小鼠体内该基因的缺失会导致对饮食诱导的抵抗力。肥胖以及胆固醇和甘油三酯代谢节律的改变，表明它是一个重要的在接下来的五年里，我们将专注于识别昼夜节律转录后调节因子。细胞质和线粒体中 Nocturnin 的 mRNA 底物。