Keeping time: circadian clock responses to environmental challenge

导言。这个博士项目研究我们的内部时钟如何将外部计时(如光明和黑暗环境)转换为复杂的生理节奏。它将专门研究时钟干扰对哺乳动物生理的影响，并测试钟表工作的药物靶向是否可以抵消环境或病理时钟干扰。这些研究与BBSRC关于了解生物节律和终身健康的战略倡议密切相关，并建立在曼彻斯特大学和辉瑞之间长期而成功的合作基础上。每天24小时的节律几乎存在于我们行为和生理的方方面面，从我们的睡眠-醒来周期，到体温、血压和循环激素的波动。这些节律是由内部计时系统(生物钟)驱动的，这些计时系统贯穿全身，并在每个组织内发挥作用，协调器官功能和节奏活动。在哺乳动物中，昼夜节律由一个位于大脑中称为视交叉上核(SCN)的小区域的“主时钟”主导。重要的是，SCN使大脑和身体其他部分的时钟同步，因此不同器官系统的活动相互协调，并与最重要的行为周期(即我们何时进食、何时睡觉等)相协调。SCN还通过直接传递来自视网膜的光信息来与环境保持同步。了解生物钟系统是如何工作的，以及它是如何引导不同的生理通路穿过身体变得越来越重要，因为我们现在认识到，在许多病理情况下，我们的生物钟被打乱是常见的。例如，扰乱这些生物钟的生活方式，如倒班工作，会增加癌症和糖尿病等疾病的发病率。昼夜节律紊乱也被认为是包括痴呆症和双相抑郁在内的许多神经疾病的重要特征。这项博士提案将研究内部计时器如何使我们的生理与环境保持一致，以及当这种调整被破坏时会产生什么后果。重要的是，这些研究将在分子和生理水平上详细说明生物钟的功能。在分子水平上，我们将使用时钟基因报告系统和基因/蛋白质表达的纵向测量来详细说明不同组织中的分子时钟如何对环境输入(如光或温度)的变化做出反应。这些研究将与行为和生理节律(例如，运动活动、产热、摄食行为、代谢率)的综合测量相平行，使用环境挑战模型(例如，光/暗周期的反复转换；类似于慢性轮班工作)和不适当夹带的遗传模型(例如，CK1etau和aft突变小鼠，它们模拟人类家族的高级睡眠阶段和延迟睡眠阶段)。这也将使我们能够测试时钟重新设置刺激和药物(例如CK1e拮抗剂)如何影响广泛的生理节律。这些研究将受益于一种令人兴奋的新方法来跟踪自由活动小鼠的基因活动振荡。这是通过注射含有发光基因的病毒来实现的，发光基因会随着特定时钟驱动或代谢途径的激活而振荡。因此，我们可以跟踪给定组织的核心发条如何对改变的环境和/或药物靶向做出反应。

Introduction. This PhD project examines how our internal clocks translate external timing (such as the light and dark environment) into complex physiological rhythms. It will specifically address the impact of clock disruption on mammalian physiology, and test whether pharmacological targeting of the clockwork may counteract environmental or pathological clock disruption. These studies closely align to the BBSRC's strategic initiatives on understanding biological rhythms and lifetime of health and build on a long-standing and successful collaboration between the University of Manchester and Pfizer.Background. Daily 24-hour rhythms are present in virtually all aspects of our behaviour and physiology, ranging from our sleep-wake cycle, to fluctuations in body temperature, blood pressure and circulating hormones. These rhythms are driven by internal timing systems (circadian clocks) that run throughout the body, and act within each tissue to orchestrate organ function and rhythmic activity. In mammals, circadian timing is headed by a 'master clock' located in a small area of thebrain called the suprachiasmatic nucleus (SCN). Importantly, the SCN synchronises clocks in the rest of the brain and body, so that the activities of different organ systems are coordinated with each other, as well as with overriding behavioural cycles (i.e. when we eat, when we sleep, etc.). The SCN also keeps in time with the environment through direct relays of photic information from the retina. Understanding how the circadian system works, and how it directs diverse physiological pathways cross the body has become increasingly important because we now recognize that disruption of our clocks is commonly observed with many pathological conditions. For example, lifestyles that disturb these clocks, such as shift-work, increase the incidence of diseases including cancer and diabetes. Circadian disruption is also recognized as an important feature of many neurological disorders in including dementia and bipolar depression.Methodology. This PhD proposal will examine how internal timers align our physiology to the environment and what the consequences are when that alignment is disrupted. Importantly these studies will detail circadian clock function at both a molecular and physiological level. At a molecular level we will use clock-gene reporter systems and longitudinal measures of gene/protein expression to detail how the molecular clockwork in different tissues responds to changes in environmentalinputs (such as light or temperature). These studies will be paralleled by comprehensive measures of behavioural and physiological rhythms (e.g. locomotor activity, thermogenesis, feeding behaviour, metabolic rate), using models of environmental challenge (e.g. repeated shift of the light/dark cycle; akin to chronic shift work) and genetic models of inappropriate entrainment (e.g. CK1etau and Aft mutant mice; which model human familial advanced sleep phase and delayed sleep phase). This will also allow us to test how clock re-setting stimuli and drugs (e.g. CK1e antagonists) impact on a broad-spectrum of physiological rhythms. These studies will benefit from an exciting new method to track oscillations in gene activity in free-moving mice. This is achieved by injecting a virus containing a light-emitting gene, which oscillates in response to activation of a specific clock-driven or metabolic pathway. Thus, we can track how the core clockwork of a given tissue responds to altered environment and/or to pharmacological targeting.