Maier Bert, Wendt Sabrina, Vanselow Jens T, Wallach Thomas, Reischl Silke, Oehmke Stefanie, Schlosser Andreas, Kramer Achim
Laboratory of Chronobiology, Charité-Universitätsmedizin Berlin, Berlin, Germany.
Genes Dev. 2009 Mar 15;23(6):708-18. doi: 10.1101/gad.512209.
Post-translational processes are essential for the generation and dynamics of mammalian circadian rhythms. In particular, phosphorylation of the key circadian protein PER2 precisely controls the period and phase of circadian oscillations. However, the mechanisms underlying that control are poorly understood. Here, we identified in a high-throughput RNAi-based genetic screen casein kinase 2 (CK2) as a PER2-phosphorylating kinase and novel component of the mammalian circadian clock. When CK2 subunits are silenced by RNAi or when CK2 activity is inhibited pharmacologically, circadian rhythms are disrupted. CK2 binds to PER2 in vivo, phosphorylates PER2 specifically at N-terminal residues in vitro, and supports normal nuclear PER2 accumulation. Mutation of CK2 phosphorylation sites decreases PER2 stability and copies CK2 inhibition regarding oscillation dynamics. We propose a new concept of how PER2 phosphorylation and stabilization can set the clock speed in opposite directions, dependent on the phase of action.
翻译后修饰过程对于哺乳动物昼夜节律的产生和动态变化至关重要。特别是，关键的昼夜节律蛋白PER2的磷酸化精确地控制着昼夜节律振荡的周期和相位。然而，这种控制背后的机制仍知之甚少。在这里，我们在基于RNAi的高通量基因筛选中鉴定出酪蛋白激酶2（CK2）是一种PER2磷酸化激酶，也是哺乳动物生物钟的新组成部分。当CK2亚基通过RNAi沉默或通过药理学方法抑制CK2活性时，昼夜节律会被破坏。CK2在体内与PER2结合，在体外特异性地磷酸化PER2的N端残基，并支持正常的细胞核PER2积累。CK2磷酸化位点的突变会降低PER2的稳定性，并在振荡动力学方面模拟CK2抑制。我们提出了一个新的概念，即PER2的磷酸化和稳定如何根据作用阶段在相反方向上设定生物钟速度。
