The multi-subunit GID/CTLH E3 ubiquitin ligase promotes cell proliferation and targets the transcription factor Hbp1 for degradation.
The multi-subunit GID/CTLH E3 ubiquitin ligase promotes cell proliferation and targets the transcription factor Hbp1 for degradation.
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DOI：
10.7554/elife.35528
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发表时间：
2018-06-18
期刊：
影响因子：
7.7
通讯作者：
Peter M
中科院分区：
文献类型：
--
作者：
Lampert F;Stafa D;Goga A;Soste MV;Gilberto S;Olieric N;Picotti P;Stoffel M;Peter M
在酵母中，葡萄糖诱导的降解缺陷（GID） E3连接酶选择性地降解多余的糖异生酶。在这里，我们确定了哺乳动物GID/CTLH复合体的所有亚基，并提供了其分层组织和逐步组装的全面地图。生化重组表明，哺乳动物复合物具有固有的E3泛素连接酶活性，使用Ube2H作为其同源E2。多个GID亚基的缺失会损害细胞增殖，并且这种缺陷伴随着关键细胞周期标记物如视网膜母细胞瘤（Rb）肿瘤抑制因子、磷酸化组蛋白H3和细胞周期蛋白a的失调。我们发现促增殖基因Hbp1的负调节因子是真正的GID/CTLH蛋白水解底物。事实上，Hbp1在缺乏GID/CTLH活性的细胞中积累，Hbp1在体外通过重组的GID/CTLH复合物进行物理相互作用并泛素化。因此，我们的生化和细胞分析表明，GID/CTLH复合物至少在一定程度上通过降解Hbp1阻止了G1期细胞周期的退出。
In yeast, the glucose-induced degradation-deficient (GID) E3 ligase selectively degrades superfluous gluconeogenic enzymes. Here, we identified all subunits of the mammalian GID/CTLH complex and provide a comprehensive map of its hierarchical organization and step-wise assembly. Biochemical reconstitution demonstrates that the mammalian complex possesses inherent E3 ubiquitin ligase activity, using Ube2H as its cognate E2. Deletions of multiple GID subunits compromise cell proliferation, and this defect is accompanied by deregulation of critical cell cycle markers such as the retinoblastoma (Rb) tumor suppressor, phospho-Histone H3 and Cyclin A. We identify the negative regulator of pro-proliferative genes Hbp1 as a bonafide GID/CTLH proteolytic substrate. Indeed, Hbp1 accumulates in cells lacking GID/CTLH activity, and Hbp1 physically interacts and is ubiquitinated in vitro by reconstituted GID/CTLH complexes. Our biochemical and cellular analysis thus demonstrates that the GID/CTLH complex prevents cell cycle exit in G1, at least in part by degrading Hbp1.