Uncovering the Gene Regulatory Mechanisms Governing the Aging Circadian Clock

项目概要： 生物钟是细胞功能和稳态的重要调节器。年龄- 人类昼夜节律系统中的相关改变与神经元病理学有关。 最近在果蝇和小鼠中的证据表明，节律紊乱与 神经变性;然而，对所涉及的机制知之甚少。解决这些 机制，我们比较了昼夜转录组在头部的年轻和老年果蝇使用 RNA测序我们发现在幼蝇中有节奏地表达的几个基因 失去循环模式，成为组成性低或高的老苍蝇。我们发现了一群 基因，这些基因在年轻果蝇的头部是低的和有节奏的，但在 老苍蝇的头。这一组包含已知的应激反应基因， 年轻的果蝇对氧化应激或缺氧的反应。根据初步数据，我们 假设生物钟协调神经保护基因的节律性表达， 被称为晚期生命周期（LLC），响应内在压力和老化神经系统的损伤， 系统在目标1中，我们将测量核心昼夜节律转录的全基因组结合， 因子CLK和CYC通过ChIP-Seq和确定年龄特异性结合事件， 对这些监管变化负责。在目标2中，我们将测量染色质修饰 H3 K4 me 3和H3 K27 me 3以及RNA聚合酶II结合，使用ChIP-Seq在H3 K27 me 3周围进行。 在年轻和年老的苍蝇头上的时钟，以表征年龄改变的染色质状态的影响， 与衰老有关的转录变化。在目标3中，我们将测量microRNA表达， 在年轻和年老的果蝇中，识别年龄改变的microRNA调控事件， 可能导致基因表达节奏的转录后变化。拟议工作 应该揭示保护大脑免受年龄相关损伤的时钟控制途径。鉴于 生物钟和衰老生物学的保守分子基础，我们预计这些途径将 也在人类中发挥作用。 !

PROJECT SUMMARY: Circadian clocks are important regulators of cellular functions and homeostasis. Age- related alterations in the human circadian system are implicated in neuronal pathologies. Recent evidence in fruit flies and mice suggests correlation between disrupted rhythms and neurodegeneration; however, very little is known about mechanisms involved. To address these mechanisms, we compared circadian transcriptome in heads of young and old Drosophila using RNA-seq. We found that several genes that were expressed in young flies in a rhythmic fashion lose cycling pattern to become constitutively low or high in old flies. We uncovered a group of genes, which were low and arrhythmic in heads of young flies but became strongly rhythmic in heads of old flies. This group contains known stress-responsive genes that are induced in young flies in response to oxidative stress or hypoxia. Based on our preliminary data, we hypothesize that clock orchestrates rhythmic expression of neuroprotective genes, which we termed late life cyclers (LLCs), in response to intrinsic stress and damage in the aging nervous system. In Aim 1, we will measure genome-wide binding of the core circadian transcription factors CLK and CYC through ChIP-Seq and identify age-specific binding events that could be responsible for these regulatory changes. In Aim 2, we will measure chromatin modifications H3K4me3 and H3K27me3 as well as RNA Polymerase II binding using ChIP-Seq around the clock in young and old fly heads to characterize the effect of age-altered chromatin state and transcriptional changes associated with aging. In Aim 3, we will measure microRNA expression around the clock in young and old flies, to identify age-altered microRNA regulatory events that could result in post-transcriptional changes in rhythmic gene expression. The proposed work should reveal clock-controlled pathways that protect brain from age-related damage. Given the conserved molecular basis of circadian clock and aging biology, we expect these pathways will also function in humans. !