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，生理和行为计时 自行车.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 抑郁症与生物钟和大脑之间的失调有关。 外部环境目前的模型假设昼夜节律振荡器保持 时间通过复杂的转录和转录后反馈回路。的 由无时间（tim）编码的昼夜节律分量在 生物钟结构。TIM对于昼夜节律至关重要， 同时，构成外部信号的入口点，例如光和 温度，进入核心昼夜节律机器。 最近，我们发现了几种mRNA和蛋白质亚型的存在， 通过交替处理从TIM生成。这些同种型经受 不同类型的调节和编码具有不同性质的蛋白质，这表明 介导TIM功能的机制比以前更复杂 不过重要的是，我们发现温度强烈地调节了 在给定时间产生的不同RNA亚型，可能是通过直接作用于时间， 前mRNA加工。重要的是，我们发现消除一种异构体 （称为TIM-S）导致异常的运动活动和昼夜节律， 这表明了这一规定的重要性。 该提案旨在揭示时间替代RNA加工对于 昼夜节律系统的鲁棒性和可塑性。为此，我们将 首先产生FLY，其中TIM的选择性剪接被锁定在一种状态。这 能让我们确定不同亚型的功能我们将遵循 表征这些TIM同种型的作用模式。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。 总之，本项目将阐明tim选择性剪接的机制， 阐明不同的TIM和PER mRNA和蛋白质同种型的功能。

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.