The non-classical nuclear import carrier Transportin 1 modulates circadian rhythms through its effect on PER1 nuclear localization
The non-classical nuclear import carrier Transportin 1 modulates circadian rhythms through its effect on PER1 nuclear localization
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DOI：
10.1371/journal.pgen.1007189
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发表时间：
2018-01-01
期刊：
影响因子：
4.5
通讯作者：
Kramer, Achim
中科院分区：
文献类型：
--
作者：
Korge, Sandra;Maier, Bert;Kramer, Achim
生物钟是一种分子计时机制，允许生物体预测其环境中的每日变化。这些生物钟的基本细胞基础是延迟负反馈基因调节，其中含有蛋白复合物的PERIOD和光敏色素作为主要抑制元件。对于一个正确的昼夜节律周期，这是至关重要的，这样的时钟蛋白复合物在细胞核中积累在一个精确的定时方式，一个机制是知之甚少。我们在人类细胞中进行了系统的RNAi介导的筛选，并确定了15个与核质易位机制相关的基因，这些基因的表达对生物钟动态很重要。其中包括转运蛋白1（TNPO 1），一种非经典的核输入载体，其敲除和敲除导致短的昼夜节律周期。TNPO 1被发现在内源性时钟蛋白复合物，特别是结合到PER1调节其（而不是PER2的）核定位。虽然PER 1也通过经典的Importin β介导的途径转运到细胞核，但TNPO 1消耗减慢了PER 1核输入速率，正如光漂白后荧光恢复（FRAP）实验所揭示的那样。此外，我们发现TNPO 1介导的核输入可能构成了一种新的输入途径，细胞氧化还原状态信号的时钟，因为氧化还原应激增加TNPO 1的结合PER1和减少其核定位。总之，我们的RNAi筛选敲除输入载体（但也敲除输出载体）导致短和长的昼夜节律周期，这表明控制时钟蛋白亚细胞定位时间的调控途径比以前假设的要复杂得多。TNPO 1是正常昼夜节律周期所必需的新参与者之一，并可能用于生物钟的氧化还原调节。
Circadian clocks are molecular timekeeping mechanisms that allow organisms to anticipate daily changes in their environment. The fundamental cellular basis of these clocks is delayed negative feedback gene regulation with PERIOD and CRYPTOCHROME containing protein complexes as main inhibitory elements. For a correct circadian period, it is essential that such clock protein complexes accumulate in the nucleus in a precisely timed manner, a mechanism that is poorly understood. We performed a systematic RNAi-mediated screen in human cells and identified 15 genes associated with the nucleo-cytoplasmic translocation machinery, whose expression is important for circadian clock dynamics. Among them was Transportin 1 (TNPO1), a non-classical nuclear import carrier, whose knockdown and knockout led to short circadian periods. TNPO1 was found in endogenous clock protein complexes and particularly binds to PER1 regulating its (but not PER2's) nuclear localization. While PER1 is also transported to the nucleus by the classical, Importin beta-mediated pathway, TNPO1 depletion slowed down PER1 nuclear import rate as revealed by fluorescence recovery after photobleaching (FRAP) experiments. In addition, we found that TNPO1-mediated nuclear import may constitute a novel input pathway of how cellular redox state signals to the clock, since redox stress increases binding of TNPO1 to PER1 and decreases its nuclear localization. Together, our RNAi screen knocking down import carriers (but also export carriers) results in short and long circadian periods indicating that the regulatory pathways that control the timing of clock protein subcellular localization are far more complex than previously assumed. TNPO1 is one of the novel players essential for normal circadian periods and potentially for redox regulation of the clock.