Role for Slimb in the degradation of Drosophila Period protein phosphorylated by Doubletime
Role for Slimb in the degradation of Drosophila Period protein phosphorylated by Doubletime
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DOI：
10.1038/nature01272
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发表时间：
2002-12-12
期刊：
影响因子：
64.8
通讯作者：
Edery, I
中科院分区：
文献类型：
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作者：
Ko, HW;Jiang, J;Edery, I
蛋白质磷酸化在调节生物钟蛋白的稳定性方面具有关键作用，其方式与一天中的特定时间有关(1)。动物时钟的一个保守特征是周期（Per）蛋白在磷酸化和水平上经历每日节律（2,3），这些事件对正常时钟进程至关重要（4-7）。酪蛋白激酶Iepsilon （CKIepsilon）在调节动物Per蛋白的磷酸化和丰度方面具有突出作用(8)。这首先在果蝇中被证实为Doubletime (Dbt)，一种脊椎动物酪蛋白激酶Iepsilon的同源物（4,6）。然而，目前尚不清楚Dbt是如何调节Per水平的。在这里，我们通过细胞培养系统表明，Dbt促进Per的渐进式磷酸化，通过泛素-蛋白酶体途径导致过度磷酸化的异构体的快速降解。Slimb是一种F-box/WD40-repeat蛋白，在泛素-蛋白酶体途径中发挥作用（9,10），优先与磷酸化的Per相互作用并刺激其降解。slimb的过度表达或slimb的显性阴性版本时钟细胞的表达破坏了正常的节律活动在苍蝇。我们的研究结果表明，过度磷酸化的Per通过与sllimb相互作用靶向蛋白酶体。
Protein phosphorylation has a key role in modulating the stabilities of circadian clock proteins in a manner specific to the time of day(1). A conserved feature of animal clocks is that Period (Per) proteins undergo daily rhythms in phosphorylation and levels(2,3), events that are crucial for normal clock progression(4-7). Casein kinase Iepsilon (CKIepsilon) has a prominent role in regulating the phosphorylation and abundance of Per proteins in animals(8). This was first shown in Drosophila with the characterization of Doubletime (Dbt), a homologue of vertebrate casein kinase Iepsilon(4,6). However, it is not clear how Dbt regulates the levels of Per. Here we show, using a cell culture system, that Dbt promotes the progressive phosphorylation of Per, leading to the rapid degradation of hyperphosphorylated isoforms by the ubiquitin-proteasome pathway. Slimb, an F-box/WD40-repeat protein functioning in the ubiquitin-proteasome pathway(9,10) interacts preferentially with phosphorylated Per and stimulates its degradation. Overexpression of slimb or expression in clock cells of a dominant-negative version of slimb disrupts normal rhythmic activity in flies. Our findings suggest that hyperphosphorylated Per is targeted to the proteasome by interactions with Slimb.