Control of WHITE COLLAR localization by phosphorylation is a critical step in the circadian negative feedback process
Control of WHITE COLLAR localization by phosphorylation is a critical step in the circadian negative feedback process
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DOI：
10.1038/emboj.2008.245
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发表时间：
2008-12-17
期刊：
影响因子：
11.4
通讯作者：
Liu, Yi
中科院分区：
文献类型：
--
作者：
Cha, Joonseok;Chang, Shwu-Shin;Liu, Yi
可逆蛋白磷酸化在真核生物昼夜节律负反馈回路中具有重要作用。在神经孢子菌中，FREQUENCY蛋白通过促进其转录激活子WHITE COLLAR复合物（WCC）的磷酸化，从而抑制WCC的活性，从而关闭昼夜节律负反馈回路。在这里，我们表明蛋白磷酸酶4是神经孢子菌时钟的一个新组成部分，通过调节昼夜节律负反馈回路的两个过程。pp4的破坏导致低振幅的短周期节律。除了调节FRQ磷酸化和稳定性外，PP4还可以去磷酸化并激活WCC。与另一种激活WCC的磷酸酶PP2A相反，PP4在促进WCC的核进入中起主要作用。PKA是一种WC激酶，可抑制WC核的定位。此外，依赖frq的WC磷酸化促进了WCC的胞质定位。总之，这些结果揭示了WCC核胞质穿梭是昼夜节律负反馈过程中的一个重要步骤，并将frq依赖性的WCC抑制描述为两个步骤的过程：抑制WCC dna结合活性，然后将WCC隔离到细胞质中。
Reversible protein phosphorylation has critical functions in the eukaryotic circadian negative feedback loops. In Neurospora, the FREQUENCY protein closes the circadian negative feedback loop by promoting the phosphorylation of its transcription activator, the WHITE COLLAR complex (WCC) and consequently inhibiting WCC activity. Here we show that protein phosphatase 4 is a novel component of the Neurospora clock by regulating both processes of the circadian negative feedback loop. The disruption of pp4 results in short period rhythms with low amplitude. In addition to its role in regulating FRQ phosphorylation and stability, PP4 also dephosphorylates and activates WCC. In contrast to PP2A, another phosphatase that activates WCC, PP4 has a major function in promoting nuclear entry of WCC. PKA, a WC kinase, inhibits WC nuclear localization. Furthermore, the FRQ-dependent WC phosphorylation promotes WCC cytosolic localization. Together, these results revealed WCC nucleocytoplasmic shuttling as an important step in the circadian negative feedback process and delineated the FRQ-dependent WCC inhibition as a two-step process: the inhibition of WCC DNA-binding activity followed by sequestration of WCC into the cytoplasm.