Understanding rhythmic gene regulatory mechanisms in the mammalian circadian system

摘要 昼夜节律是生物、生理和行为过程，使有机体能够 应对地球自转引起的环境变化。有趣的是，最近的数据开始 揭示了衰老对昼夜节律的影响。例如，昼夜节律过程，如褪黑激素 分泌和睡眠的开始，随着人类年龄的增长，在昼夜周期中呈阶段性提前。此外， 与幼鼠肝脏相比，老年小鼠肝脏节律性表达基因的数量减少了23%。 此外，近一半在老年小鼠肝脏中有节律性表达的mrna在 幼鼠肝脏。这些数据清楚地表明，衰老过程改变了 驱动有节律性的mRNA表达。然而，目前还不清楚衰老是如何改变人的数量和身份的 有节律性表达的mRNAs。这项提议的目标是了解分子机制是如何 调节节律基因的表达随着年龄的增长而改变，以及衰老对昼夜节律周期的影响。 拟议项目的成功完成将揭示与年龄有关的机制变化， 驱动昼夜节律基因的表达，被认为在驱动和维持昼夜节律方面发挥关键作用 各种下游生物过程。为了有节奏地表达信使核糖核酸； 退化，或者两者的结合，必须是有节奏的。此外，平均信使核糖核酸的半衰期必须是 短到足以让RNA每天被新合成。在目标1中，我们将通过实验测量昼夜节律 幼龄和老年小鼠的mRNA表达、合成和降解速率的变化 成纤维细胞评估这些过程中的哪一个最容易受到年龄相关的驾驶节律变化的影响 基因表达。在目标2中，我们将用生物信息学的方法测量mrna表达的昼夜变化。 利用公开可用的昼夜rna-seq数据集在果蝇大脑中的合成降解率。 识别驱动昼夜节律基因表达的年龄相关变化最终可以帮助我们发展 缓解随年龄增长的昼夜节律紊乱的诊断工具和干预策略。现代生活方式 包含许多扰乱核心时钟机制的刺激，如晚上手机发出的强光，时差， 上夜班。我们必须了解驱动昼夜节律的机制是如何变化的 随着年龄的增长，防止昼夜节律失调，这可能会随着年龄的增长而加剧。

Summary Circadian rhythms are biological, physiological, and behavioral processes that enable organisms to respond to the environmental changes caused by the rotation of the Earth. Interestingly, recent data started to shed light into the impact of aging on circadian rhythms. For example, circadian processes, such as melatonin secretion and onset of sleep, are phase-advanced in the circadian cycle as humans age. Moreover, the number of rhythmically expressed genes is reduced by 23% in old mouse liver compared to young mouse liver. Furthermore, nearly half of mRNA expressed rhythmically in old mouse liver are not expressed rhythmically in young mouse liver. These data clearly indicate that the aging process changes the molecular mechanisms that drive rhythmic mRNA expression. However, it remains unclear how aging alters the number and identity of rhythmically expressed mRNAs. The goal of this proposal is to understand how the molecular mechanisms that regulate rhythmic gene expression are altered with age and what impact aging has on the circadian cycle. Successful accomplishment of the proposed project will uncover age-related changes to the mechanisms that drive circadian gene expression that are thought to play key roles in driving and maintaining circadian rhythms of various downstream biological processes. For an mRNA to be rhythmically expressed; synthesis, degradation, or a combination of the two must be rhythmic. Additionally, the average mRNA half-life must be short enough for RNA to be newly synthesized each day. In Aim 1, we will experimentally measure circadian changes of mRNA expression, mRNA synthesis and degradation rates both in young and old mouse fibroblasts to evaluate which of these processes is most susceptible to age-related changes in driving rhythmic gene expression. In Aim 2, we will bioinformatically measure circadian changes of mRNA expression, mRNA synthesis degradation rates in fly brain by leveraging circadian RNA-seq datasets that are publicly available. Identification of age-related changes in driving circadian gene expression can ultimately help us develop diagnostic tools and intervention strategies to mitigate circadian disturbances with age. Modern lifestyles contain many stimuli that disrupt the core-clock mechanism such as bright light at night from phones, jet-lag, and night shift work. It is critical that we understand how the mechanisms that drive circadian rhythms change with age to prevent circadian dysregulation that may be exacerbated with age.