Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Division of Chronobiology, Berlin 10117, Germany.
Institute for Theoretical Biology, Charité-Universitätsmedizin Berlin, Berlin 10115, Germany.
Proc Natl Acad Sci U S A. 2024 Aug 20;121(34):e2404738121. doi: 10.1073/pnas.2404738121. Epub 2024 Aug 14.
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.
大多数哺乳动物细胞都有分子生物钟，它们会产生广泛的转录物和蛋白质丰度的节律。虽然生物钟对细胞环境的波动具有很强的鲁棒性，但对于生物钟周期如何补偿代谢状态的波动知之甚少。在这里，我们利用单个细胞在生物钟周期和代谢参数-蛋白质稳定性方面的异质性，在不需要遗传操作的情况下研究它们的相互依赖性。我们生成了表达关键生物钟蛋白（CRYTOCHROME1/2 (CRY1/2) 和 PERIOD1/2 (PER1/2)）的细胞，这些蛋白作为内源性融合蛋白与荧光蛋白表达，并同时监测数千个单个细胞中的生物钟节律和降解。我们发现生物钟周期补偿了生物钟抑制蛋白的周转率波动，并使用数学模型揭示了可能的机制。此外，抑制蛋白的稳定性与生物钟相位有关，并且与生物钟周期呈相位依赖性相关，这与流行的模型相反。
