Cu14A and DDB1 associate with Skp2 to target p27Kip1 for proteolysis involving the COP9 signalosome
Cu14A and DDB1 associate with Skp2 to target p27Kip1 for proteolysis involving the COP9 signalosome
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DOI：
10.1128/mcb.26.7.2531-2539.2006
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发表时间：
2006-04-01
影响因子：
5.3
通讯作者：
Raychaudhuri, P
中科院分区：
文献类型：
--
作者：
Bondar, T;Kalinina, A;Raychaudhuri, P
DDB1是受损DNA结合蛋白DDB的一个亚基，也被证明是E3泛素连接酶cullin家族成员Cul4A的接头。Cul4A-DDB1复合体仍然与COP9信号体相关，这种相互作用从分裂酵母到人类都是保守的。对裂解酵母的研究表明，PCu4-DDB1-信号体复合体在复制抑制物Spd1的蛋白质分解中发挥了作用。在这里，我们提供了证据，证明复制抑制蛋白分解的功能在哺乳动物DDB1-Cul4A-信号体复合体中是保守的。我们发现，在哺乳动物细胞中，小干扰RNA介导的DDB1、CSN1(信号体的一个亚单位)和Cul4A的敲除导致p27(KIPL)的积累。此外，DDB1的表达通过增加p27(KIPL)的衰减率而降低其水平。DDB1诱导的p27(KIPL)蛋白降解需要信号体和Cul4A，因为DDB1不能增加缺乏CSN1或Cul4A的细胞中P27(KIPL)的衰减率。令人惊讶的是，DDB1诱导的p2蛋白分解(KIPL)也涉及Skp2，这是一种F-box蛋白，允许通过Skpl-cull-F-box复合体靶向p27(KIPL)进行泛素化。此外，我们还提供了Cul4A、DDB1和Skp2之间存在物理关联的证据。我们推测，F-box蛋白Skp2除了利用CULL-Skp1外，还利用Cu14A-DDB1诱导p27(KIPL)的蛋白降解。
DDB1, a subunit of the damaged-DNA binding protein DDB, has been shown to function also as an adaptor for Cul4A, a member of the cullin family of E3 ubiquitin ligase. The Cul4A-DDB1 complex remains associated with the COP9 signalosome, and that interaction is conserved from fission yeast to human. Studies with fission yeast suggested a role of the Pcu4-Ddb1-signalosome complex in the proteolysis of the replication inhibitor Spd1. Here we provide evidence that the function of replication inhibitor proteolysis is conserved in the mammalian DDB1-Cul4A-signalosome complex. We show that small interfering RNA-mediated knockdown of DDB1, CSN1 (a subunit of the signalosome), and Cul4A in mammalian cells causes an accumulation of p27(Kipl). Moreover, expression of DDB1 reduces the level of p27(Kipl) by increasing its decay rate. The DDB1-induced proteolysis of p27(Kipl) requires signalosome and Cul4A, because DDB1 failed to increase the decay rate of P27(Kipl) in cells deficient in CSN1 or Cul4A. Surprisingly, the DDB1-induced proteolysis of p2(Kipl) also involves Skp2, an F-box protein that allows targeting of p27(Kipl) for ubiquitination by the Skpl-Cull-F-box complex. Moreover, we provide evidence for a physical association between Cul4A, DDB1, and Skp2. We speculate that the F-box protein Skp2, in addition to utilizing Cull-Skpl, utilizes Cu14A-DDB1 to induce proteolysis of p27(Kipl).