Ubiquitination and degradation of homeodomain-interacting protein kinase 2 by WD40 repeat/SOCS box protein WSB-1
Ubiquitination and degradation of homeodomain-interacting protein kinase 2 by WD40 repeat/SOCS box protein WSB-1
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DOI：
10.1074/jbc.m708873200
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发表时间：
2008-02-22
影响因子：
4.8
通讯作者：
Choi, Cheol Yong
中科院分区：
文献类型：
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作者：
Choi, Dong Wook;Seo, Yu-Mi;Choi, Cheol Yong
同源结构域相互作用蛋白激酶 2 (HIPK2) 是核蛋白激酶家族的成员，可诱导 p53 和 CtBP 介导的细胞凋亡。紫外线照射和顺铂处理使 HIPK2 水平升高，这表明正常条件下细胞内 HIPK2 发生了降解。在这里，我们表明 HIPK2 被 WD40 重复/SOCS 盒蛋白 WSB-1 泛素化和降解，该过程在 DNA 损伤条件下被阻断。进行酵母双杂交筛选以确定与 HIPK2 相互作用的蛋白质。 WSB-1 是一种 E3 泛素连接酶，被定性为 HIPK2 相互作用蛋白。 WSB-1 的共表达导致 HIPK2 通过其 C 末端区域降解。 WSB-1 的结构域分析表明，WD40 重复序列和 SOCS 盒分别是其与 HIPK2 相互作用和降解 HIPK2 所必需的。为了支持 WSB-1 对 HIPK2 的降解，HIPK2 在体外和体内均被 WSB-1 多泛素化。通过针对 WSB-1 的短发夹 RNA 表达来敲低内源性 WSB-1，增加了内源性 HIPK2 的稳定性，并导致 HIPK2 的积累。通过给予DNA损伤试剂，包括阿霉素和顺铂，WSB-1对HIPK2的泛素化和降解被完全抑制。这些发现有效地说明了正常条件下细胞中 HIPK2 通过 WSB-1 维持在低水平并通过基因毒性应激稳定的调节机制。
Homeodomain-interacting protein kinase 2 (HIPK2) is a member of the nuclear protein kinase family, which induces both p53- and CtBP-mediated apoptosis. Levels of HIPK2 were increased by UV irradiation and cisplatin treatment, thereby implying the degradation of HIPK2 in cells under normal conditions. Here, we indicate that HIPK2 is ubiquitinated and degraded by the WD40-repeat/SOCS box protein WSB-1, a process that is blocked under DNA damage conditions. Yeast two-hybrid screening was conducted to identify the proteins that interact with HIPK2. WSB-1, an E3 ubiquitin ligase, was characterized as an HIPK2-interacting protein. The coexpression of WSB-1 resulted in the degradation of HIPK2 via its C-terminal region. Domain analysis of WSB-1 showed that WD40-repeats and the SOCS box were required for its interaction with and degradation of HIPK2, respectively. In support of the degradation of HIPK2 by WSB-1, HIPK2 was polyubiquitinated by WSB-1 in vitro and in vivo. The knockdown of endogenous WSB-1 with the expression of short hairpin RNA against WSB-1 increases the stability of endogenous HIPK2 and resulted in the accumulation of HIPK2. The ubiquitination and degradation of HIPK2 by WSB-1 was inhibited completely via the administration of DNA damage reagents, including Adriamycin and cisplatin. These findings effectively illustrate the regulatory mechanisms by which HIPK2 is maintained at a low level, by WSB-1 in cells under normal conditions, and stabilized by genotoxic stresses.