Ultradian to circadian transcriptome re-wiring underlies liver aging

项目总结/摘要 除了昼夜节律（~ 24小时振荡）外，还存在超昼夜节律（周期小于24小时）， 其中12小时节律在多个物种中被发现， 线虫C.和哺乳动物如老鼠狒狒甚至人类。我们小组最近发现了一个 哺乳动物的12小时生物钟是进化保守的，细胞自主的，独立于生物钟而建立。 生物钟，但依赖于未折叠蛋白反应转录因子XBP 1 s。肝脏特异 XBP 1的缺失全面损害小鼠12小时转录组，但不损害体内的昼夜节律。XBP1s- 依赖性肝脏12小时转录组优先在黎明和黄昏达到峰值，并且在 调节先天免疫功能和内质网（ER）和高尔基体的途径 稳态，包括翻译调节，ER和高尔基体中的蛋白质加工和分选，蛋白质质量 控制和鞘脂和甘油脂代谢。这些通路在衰老过程中经常失调， 与衰老有关的疾病。虽然最近已经确定，24小时昼夜节律经历普遍的 老化过程中的重编程，12小时时钟失调是否也与老化和/或老化有因果关系- 相关疾病的定义仍不明确。非常有趣的是，初步数据显示， 小鼠肝脏衰老过程中12小时循环转录组重编程为24小时昼夜节律， 进一步与12小时肝脏XBP 1 s振荡向24小时昼夜节律振荡的转换有关。基于 根据这些发现，我们假设12小时到24小时（昼夜节律）的重新编程可以加速肝脏衰老。我们将 产生肝脏12小时至24小时重编程的小鼠模型。广泛的表型实验将 以确定遗传诱导的12小时至24小时重编程是否足以驱动肝脏老化。 小鼠我们将进一步进行时间RNA-Seq和肝分泌组分析，以确定分子 这一重新编程的潜在机制。因此，这项工作将建立12小时生物钟失调作为一种新的 这表明，旨在防止这种12小时至24小时重编程的新疗法可以 能有效改善人类的健康寿命。

Project Summary/Abstract In addition to the circadian rhythms (~24h oscillation), ultradian rhythms (with period smaller than 24h) also exist, among which 12h rhythms were prevalently found in multiple species ranging from circatidal marine animals, to nematode C. elegans and mammals like mouse, baboon and even humans. Our group recently discovered a mammalian 12h-clock that is evolutionarily conserved, cell-autonomous and established independently from the circadian clock but dependent on the unfolded protein response transcription factor XBP1s. Liver-specific deletion of XBP1s globally impairs the murine 12h transcriptome, but not circadian rhythms in vivo. XBP1s- dependent hepatic 12h transcriptome preferentially peaks at dawn and dusk, and is remarkably enriched in pathways regulating innate immune functions and endoplasmic reticulum (ER) and the Golgi apparatus homeostasis, including translation regulation, protein processing and sorting in ER and Golgi, protein quality control and sphingolipid and glycerolipid metabolism. These pathways are often dysregulated during aging and aging-related diseases. While it has been recently established that the 24h circadian rhythms undergo prevalent reprogramming during aging, whether the 12h-clock dysregulation is also causally linked to aging and/or aging- related diseases remains ill defined. Very intriguingly, preliminary data revealed a very robust global reprogramming of 12h-cycling transcriptome to 24h circadian rhythms during aging in mouse liver, which is further associated with a conversion of 12h hepatic XBP1s oscillation to 24h circadian oscillation. Based upon these findings, we hypothesize that 12h-to-24h (circadian) reprogramming can accelerate liver aging. We will generate mouse models of hepatic 12h-to-24h reprogramming. Extensive phenotyping experiments will be performed to determine if genetically-induced 12h-to-24h reprogramming is sufficient to drive hepatic aging in mice. We will further perform temporal RNA-Seq and hepatic secretome profiling to identify the molecular mechanism underlying this reprogramming. This work will therefore establish 12h-clock dysregulation as a novel hallmark of aging and suggest that new therapeutics aimed at preventing this 12h-to-24h reprogramming could be effective at improving health span in humans.