Characterizing a new role for timeless in the generation of robust and plastic circadian rhythms

项目摘要 生物钟在24小时内组织细胞、生理和行为的计时 循环。了解昼夜节律是如何产生、维持和 适应不断变化的条件是关键。事实上，几种疾病，如癌症和 抑郁与生物钟和生物钟之间的错位有关 外部环境。目前的模型假设昼夜节律振荡器 时间通过复杂的转录和转录后反馈环进行。这个 由Timless(TIM)编码的昼夜节律分量在 昼夜节律的时钟结构。TIM对于昼夜节律是必不可少的，在 同时，构成外部信号的入口点，如光和 温度，进入核心的昼夜节律机器。 最近，我们发现了几种mrna和蛋白质亚型的存在。 通过替代处理从TIM生成。这些异构体受到 不同类型的调控和编码具有不同性质的蛋白质，提示 TIM功能的调节机制比以前更加复杂 尽管如此。重要的是，我们发现温度强烈地调节着相对水平。 在给定时间产生的不同RNA异构体，可能是通过直接作用于时间 前信使核糖核酸加工。重要的是，我们发现一种异构体的消除 (名为提姆-S)导致异常运动活动和昼夜节律， 论证了这一规定的重要性。 该提案旨在揭示TIM替代RNA处理对 昼夜节律系统的稳定性和可塑性。为了做到这一点，我们将 首先生成Fly，其中TIM的可选剪接被锁定到一种状态。这 将使我们能够确定不同亚型的功能。我们将紧跟着 表征这些TIM异构体的作用模式。最后但同样重要的是，我们将 确定温度调节TIM选择性剪接的机制。 综上所述，本项目将阐明TIM选择性剪接和 阐明TIM和PER不同的mRNA和蛋白质亚型的功能。

Project Summary Circadian clocks organize cellular, physiological and behavioral timing in 24-hour cycles. Understanding how circadian rhythms are generated, maintained and adapted to changing conditions is key. Indeed, several diseases such as cancer and depression are associated with a misalignment between the circadian clock and the external environment. The current model postulates that circadian oscillators keep time by complex transcriptional and post-transcriptional feedback loops. The circadian component encoded by timeless (tim) has a special place at the center of the circadian clock architecture. TIM is essential for circadian rhythms and, at the same time, constitutes an entry point for external signals, such as light and temperature, into the core circadian machinery. Recently, we uncovered the existence of several mRNA and protein isoforms generated from tim by alternative processing. These isoforms are subjected to different types of regulation and encode proteins with different properties, suggesting that the mechanisms mediating tim function are more complex than previously though. Importantly, we found that temperature strongly regulates the relative levels of the different RNA isoforms produced at a given time, likely by acting directly on tim pre-mRNA processing. Importantly, we have found that elimination of one isoform (named tim-s) results in abnormal locomotor activity and circadian rhythms, demonstrating the importance of this regulation. This proposal aims to unravel the importance of tim alternative RNA processing for the robustness and plasticity of the circadian system. In order to do so, we will first generate flies in which the alternative splicing of tim is locked into one state. This will allow us to determine the functionality of the different isoforms. We will follow by characterizing the mode of action of these tim isoforms. Last but not least, we will determine the mechanisms by which temperature regulates tim alternative splicing. In sum, this project will illuminate the mechanism of tim alternative splicing and elucidate the functions of the different tim and per mRNA and protein isoforms.