哺乳动物核受体对生物节律的鲁棒性的增强作用及机制研究

In mammals, circadian oscillation depends on the complex transcriptional network comprised of the interaction among core clock genes via E box, RRE, D box and other DNA elements. Wherein, as important clock genes, the nuclear receptor genes Rev-Erbs and RORs participate in clock feedback loop by regulating RRE activity, which is essential for maintaining clock robustness. Recent studies suggested that in addition to Rev-Erbs and RORs, most clock controlled nuclear receptors may also be involved in the regulation of circadian rhythms. We comprehensively investigated the influences of nuclear receptor knockout on circadian rhythms in our preliminary study. We found single knockout of nuclear receptor just causes subtle changes in circadian rhythms, and multiple knockout of homologous nuclear receptors response to the same transcriptional element significantly impairs the robustness of circadian clock. These results indicated that rhythmic activity of elements regulated by nuclear receptors may play a critical role in maintaining clock robustness. We aim to further reveal the molecular basis for clock robustness enhanced by nuclear receptors and explore the role of nuclear receptors in linking metabolism to circadian clock. This study will be greatly helpful for the further comprehension of clock mechanism.

生物钟基因通过E box、RRE及D box等DNA元件相互作用形成的复杂的转录调控网络是哺乳动物生物节律振荡的核心机制。其中，核受体基因Rev-Erb及ROR作为重要的生物钟基因通过调控RRE的活性参与生物钟反馈环路的形成，对生物节律鲁棒性的维持至关重要。研究结果表明，除Rev-Erb及ROR外，大多数核受体作为时钟控制基因可能同样参与生物节律的调控。我们在前期工作中比较系统全面地考察了核受体基因敲除对生物节律的影响，发现单个敲除核受体基因对生物节律影响不大，而敲除多个对同一转录元件产生应答的同源核受体基因将显著削弱生物节律的鲁棒性。结果表明，核受体可能通过节律性地作用于其应答元件来参与生物节律鲁棒性的维持。本项目拟进一步从分子、细胞、动物整体水平揭示核受体基因增强生物节律鲁棒性的机制，探索核受体基因在哺乳动物代谢对生物节律调控过程中的作用，从而增进对生物节律分子机制的了解。

在哺乳动物中，大多数生理过程均受生物节律的调控，节律紊乱将导致相关生理障碍和疾病的发生。生物钟基因通过E box、RRE及D box等DNA元件相互作用形成的复杂的转录调控网络是哺乳动物生物节律振荡的核心机制。其中，核受体基因Rev-Erb及ROR作为重要的生物钟基因通过调控RRE的活性参与生物钟反馈环路的形成，对生物节律鲁棒性的维持至关重要。研究结果表明，除Rev-Erb及ROR外，其它核受体作为时钟控制基因可能同样参与生物节律的调控。我们系统全面地考察了核受体基因敲除对生物节律的影响，发现单个敲除核受体基因对生物节律影响不大，而敲除多个对同一转录元件产生应答的同源核受体基因将显著削弱生物节律的鲁棒性，其中RARs缺失将导致细胞节律的丧失。进一步的实验证明，RARs能够与BMAL1结合并增强BMAL1对核心生物钟基因的转录。我们同时证明RARs能够参与小鼠代谢节律的稳定，介导生物钟与代谢的相互偶联，为生物钟和代谢干预以及相关疾病的治疗提供了可能的靶点。