Ser-557-phosphorylated mCRY2 is degraded upon synergistic phosphorylation by glycogen synthase kinase-3β
Ser-557-phosphorylated mCRY2 is degraded upon synergistic phosphorylation by glycogen synthase kinase-3β
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DOI：
10.1074/jbc.m506225200
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发表时间：
2005-09-09
影响因子：
4.8
通讯作者：
Fukada, Y
中科院分区：
文献类型：
--
作者：
Harada, Y;Sakai, M;Fukada, Y
隐花色素1和2作为中枢和外周生物钟的重要组成部分，用于哺乳动物昼夜节律的产生。在这里，我们表明，小鼠隐花色素2（muscle 2）是磷酸化的Ser-557在肝脏，一个很好的特点外周时钟组织。Ser-557-磷酸化形式在夜间与mGly 2蛋白平行地在肝脏中积累，并且磷酸化形式在深夜达到其最大水平，在光暗循环和恒定黑暗条件下，蛋白丰度的峰值时间之前约4小时。丝氨酸-557-磷酸化形式的mR 2位于细胞核中，而mR 2蛋白位于细胞质和细胞核中。重要的是，丝氨酸-557处的磷酸化允许随后通过糖原合成酶激酶-3 β（GSK-3 β）在丝氨酸-553处磷酸化，导致通过蛋白酶体途径有效降解mGly 2。如通过GSK-3 β在Ser-9处的磷酸化（其负调节激酶活性）所评估的，GSK-3 β在其活性中表现出昼夜节律，当mGly 2的Ser-557高度磷酸化时，其活性从深夜到清晨达到峰值。总之，本研究证明了在Ser-557/Ser-553的顺序磷酸化对mGly 2的不稳定性的重要作用，并说明了mGly 2磷酸化的昼夜调节有助于mGly 2蛋白的节律性降解的模型。
Cryptochrome 1 and 2 act as essential components of the central and peripheral circadian clocks for generation of circadian rhythms in mammals. Here we show that mouse cryptochrome 2 (mCRY2) is phosphorylated at Ser-557 in the liver, a well characterized peripheral clock tissue. The Ser-557- phosphorylated form accumulates in the liver during the night in parallel with mCRY2 protein, and the phosphorylated form reaches its maximal level at late night, preceding the peak-time of the protein abundance by similar to 4 h in both light-dark cycle and constant dark conditions. The Ser-557- phosphorylated form of mCRY2 is localized in the nucleus, whereas mCRY2 protein is located in both the cytoplasm and nucleus. Importantly, phosphorylation of mCRY2 at Ser-557 allows subsequent phosphorylation at Ser-553 by glycogen synthase kinase-3 beta (GSK-3 beta), resulting in efficient degradation of mCRY2 by a proteasome pathway. As assessed by phosphorylation of GSK-3 beta at Ser-9, which negatively regulates the kinase activity, GSK-3 beta exhibits a circadian rhythm in its activity with a peak from late night to early morning when Ser-557 of mCRY2 is highly phosphorylated. Altogether, the present study demonstrates an important role of sequential phosphorylation at Ser-557/Ser-553 for destabilization of mCRY2 and illustrates a model that the circadian regulation of mCRY2 phosphorylation contributes to rhythmic degradation of mCRY2 protein.