Mechanisms of Circadian Clock Control of mRNA Translation

mRNA 翻译的昼夜节律时钟控制机制

• 批准号: 10620952
• 负责人: Deborah Bell-Pedersen
• 金额: $ 74.93万
• 依托单位: TEXAS A&M UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-05-01 至 2028-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10620952
• 关键词: Amino Acids; Amino Acyl-tRNA Synthetases; Binding; Cell physiology; Cells; Cellular Metabolic Process; Charge; Circadian Rhythms; Defect; Disease; EIF-2alpha; Eukaryota; Genome; Health; Heart Diseases; Human; Malignant Neoplasms; Messenger RNA; Metabolic syndrome; Metabolism; Methionine; Methionine-tRNA Ligase; Modeling; Molecular Chaperones; Neurospora crassa; Periodicity; Pharmaceutical Preparations; Pharmacotherapy; Phosphorylation; Phosphotransferases; Probability; Production; Protein Biosynthesis; Proteins; Proteome; Regulation; Regulatory Pathway; Ribosomal Proteins; Ribosomes; Sleep Disorders; Terminator Codon; Testing; Time; Transfer RNA; Transfer RNA Aminoacylation; Translating; Translation Initiation; Translations; Work; circadian pacemaker; circadian regulation; drug metabolism; improved; insight; mRNA Translation; novel strategies; protein folding

Summary The circadian clock, critical to human health and drug metabolism, regulates rhythmic protein production and thus cell function and metabolism. Many proteins whose levels show robust circadian rhythms are produced from mRNAs that are not rhythmic. Using the model eukaryote Neurospora crassa, we found that up to half of this circadian regulation of protein levels is through clock control of the activities of a conserved regulator of translation initiation (eIF2α), and the protein composition of translating ribosomes. We also made the surprising observation that the circadian clock controls the probability that ribosomes will read through the normal stop codon to produce proteins with carboxy-terminal extensions and potentially new functions. In addition, we found that the clock regulates the levels of tRNA synthetases that charge tRNAs with the appropriate amino acids for translation, and thus are critical for accurate protein synthesis. Over the next 5 years, we will capitalize on these findings to test the exciting hypothesis that the circadian clock controls daily changes in translation fidelity and thus protein diversity beyond what is encoded for in the genome. We will determine if clock control of ribosome composition is necessary, and which specific ribosomal proteins are required, for rhythmic stop codon readthrough. In addition, we will test if circadian clock control of binding of the co-chaperone Zuotin to ribosomes regulates daily rhythms in protein folding. We will determine the impact of circadian rhythms in methionyl-tRNA synthetase (MetRS) levels, and rhythms in the activities of kinases that phosphorylate MetRS, on three different MetRS regulatory pathways. These include translation initiation through charging of the initiator methionyl tRNA, translation elongation through charging of elongator methionyl tRNA, and misincorporation of methionine during protein synthesis through the mischarging of non-cognate tRNA. This work will significantly impact our understanding of both how a cell is different at different times of the day, and how the proteome can be more diverse than what one would predict from the genome sequence.

概括 生物钟对人类健康和药物代谢至关重要，调节有节奏的蛋白质生产 从而影响细胞功能和新陈代谢。产生的许多蛋白质的水平显示出强大的昼夜节律 来自无节律的 mRNA。使用真核生物粗糙脉孢菌模型，我们发现多达一半的 蛋白质水平的这种昼夜节律调节是通过对保守调节器的活动进行时钟控制来实现的。 翻译起始（eIF2α）和翻译核糖体的蛋白质组成。我们还做出了令人惊讶的 观察到生物钟控制核糖体读取正常停止的概率 密码子产生具有羧基末端延伸和潜在新功能的蛋白质。此外，我们还发现 时钟调节 tRNA 合成酶的水平，这些酶为 tRNA 提供适当的氨基酸 翻译，因此对于准确的蛋白质合成至关重要。未来5年，我们将充分利用这些优势 研究结果检验了令人兴奋的假设，即生物钟控制着翻译保真度的日常变化， 因此蛋白质的多样性超出了基因组编码的范围。我们将确定核糖体的时钟控制是否 节律终止密码子的组成是必要的，并且需要哪些特定的核糖体蛋白 通读。此外，我们将测试生物钟是否控制共伴侣 Zuotin 与核糖体的结合 调节蛋白质折叠的日常节律。我们将确定昼夜节律对甲硫氨酰-tRNA 的影响 三种不同的合成酶 (MetRS) 水平以及磷酸化 MetRS 激酶的活性节律 MetRS 监管途径。这些包括通过引发剂甲硫氨酰 tRNA 的充电来启动翻译， 通过延伸子甲硫氨酰 tRNA 的充电实现翻译延伸，并在翻译过程中错误掺入甲硫氨酸 通过非同源 tRNA 的错误加载来合成蛋白质。这项工作将对我们产生重大影响 了解细胞在一天中的不同时间有何不同，以及蛋白质组如何更加丰富 与根据基因组序列预测的不同。