Translation-independent circadian control of the cell cycle in a unicellular photosynthetic eukaryote
Translation-independent circadian control of the cell cycle in a unicellular photosynthetic eukaryote
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DOI：
10.1038/ncomms4807
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发表时间：
2014-05-01
影响因子：
16.6
通讯作者：
Nakamura, Mami
中科院分区：
文献类型：
--
作者：
Miyagishima, Shin-ya;Fujiwara, Takayuki;Nakamura, Mami
细胞分裂的昼夜节律已经在真核生物的几个谱系中观察到，尤其是光合作用的单细胞真核生物。然而，细胞周期的昼夜节律调节的潜在机制和所赋予的优势的性质仍不清楚。在这里，我们利用单细胞红藻Merolae，证明了G1/S调节因子Rbr-E2F-DP复合体将G1/S的转变与昼夜节律联系起来。依赖时间的E2F磷酸化促进主观夜晚的G1/S转变，这种磷酸化事件独立于细胞周期进展而发生，即使在持续黑暗或胞浆翻译被抑制的情况下也是如此。E2F的结构性表达或RBR的耗尽将细胞周期进程从昼夜节律中分离出来。这些转基因品系比野生型暴露在更高的氧化应激下。通过RBR-E2F-DP途径在昼夜节律上抑制细胞周期进程，可能通过将光合作用和细胞周期进程暂时分开来保护细胞免受光合作用氧化应激的伤害。
Circadian rhythms of cell division have been observed in several lineages of eukaryotes, especially photosynthetic unicellular eukaryotes. However, the mechanism underlying the circadian regulation of the cell cycle and the nature of the advantage conferred remain unknown. Here, using the unicellular red alga Cyanidioschyzon merolae, we show that the G1/S regulator RBR-E2F-DP complex links the G1/S transition to circadian rhythms. Time-dependent E2F phosphorylation promotes the G1/S transition during subjective night and this phosphorylation event occurs independently of cell cycle progression, even under continuous dark or when cytosolic translation is inhibited. Constitutive expression of a phospho-mimic of E2F or depletion of RBR unlinks cell cycle progression from circadian rhythms. These transgenic lines are exposed to higher oxidative stress than the wild type. Circadian inhibition of cell cycle progression during the daytime by RBR-E2F-DP pathway likely protects cells from photosynthetic oxidative stress by temporally compartmentalizing photosynthesis and cell cycle progression.