PDF(Pubmed)
Abstract：
Most mammalian cells have molecular circadian clocks that generate widespread rhythms in transcript and protein abundance. While circadian clocks are robust to fluctuations in the cellular environment, little is known about the mechanisms by which the circadian period compensates for fluctuating metabolic states. Here, we exploit the heterogeneity of single cells both in circadian period and a metabolic parameter-protein stability-to study their interdependence without the need for genetic manipulation. We generated cells expressing key circadian proteins (CRYPTOCHROME1/2 (CRY1/2) and PERIOD1/2 (PER1/2)) as endogenous fusions with fluorescent proteins and simultaneously monitored circadian rhythms and degradation in thousands of single cells. We found that the circadian period compensates for fluctuations in the turnover rates of circadian repressor proteins and uncovered possible mechanisms using a mathematical model. In addition, the stabilities of the repressor proteins are circadian phase dependent and correlate with the circadian period in a phase-dependent manner, in contrast to the prevailing model.
摘要：
大多数哺乳动物细胞具有分子生物钟,其在转录物和蛋白质丰度中产生广泛的节律。虽然生物钟对蜂窝环境中的波动具有鲁棒性，关于昼夜节律时期补偿代谢状态波动的机制知之甚少。这里,我们利用单细胞在昼夜节律期的异质性和代谢参数-蛋白质稳定性-来研究它们的相互依赖性，而无需进行遗传操作。我们产生了表达关键昼夜节律蛋白（CRYPTOCHROME1/2（CRY1/2）和PERIOD1/2（PER1/2））的细胞，作为与荧光蛋白的内源性融合体，并同时监测数千个单细胞的昼夜节律和降解。我们发现昼夜节律可以补偿昼夜节律阻遏蛋白转换率的波动，并使用数学模型揭示了可能的机制。此外,抑制蛋白的稳定性是昼夜节律相依的，并以相依的方式与昼夜节律相关，与流行的模式相反。
