Cyclin F drives proliferation through SCF-dependent degradation of the retinoblastoma-like tumor suppressor p130/RBL2.
Cyclin F drives proliferation through SCF-dependent degradation of the retinoblastoma-like tumor suppressor p130/RBL2.
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DOI：
10.7554/elife.70691
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发表时间：
2021-12-01
期刊：
影响因子：
7.7
通讯作者：
Emanuele MJ
中科院分区：
文献类型：
--
作者：
Enrico TP;Stallaert W;Wick ET;Ngoi P;Wang X;Rubin SM;Brown NG;Purvis JE;Emanuele MJ
细胞周期基因表达程序促进了细胞增殖，在癌症中普遍处于失调状态。视网膜母细胞瘤(retinoblastoma，RB)家族蛋白RB1、RBL1/p107和RBL2/p130协同抑制细胞周期基因表达，抑制细胞增殖，抑制肿瘤发生。细胞周期蛋白依赖性蛋白对RB家族蛋白的磷酸化作用已经确立。与磷酸化一样，泛素化对细胞周期控制是必不可少的，许多增殖调节因子、肿瘤抑制因子和癌蛋白都泛素化。然而，人们对泛素信号在调控RB家族蛋白中的作用知之甚少。CRISPR/Cas9筛选的系统遗传学分析表明，细胞周期蛋白F可能调节RB网络，细胞周期蛋白F是E3连接酶SCF家族的底物识别受体。我们证明了RBL2/p130是SCFcyin F的直接底物。我们将细胞周期蛋白F的调控位点映射到p130口袋结构域的柔性连接子上，并表明该位点介导了结合、稳定性和泛素化。不能泛素化的突变型p130的表达严重损害了细胞的增殖能力和细胞周期进程。我们一致地观察到细胞周期基因转录本的表达减少，以及细胞周期蛋白丰度的减少，通过定量、迭代免疫荧光成像进行分析。这些数据表明SCFCyclin F在CDK-Rb网络中发挥关键作用，并增加了p130异常降解可能在人类癌症中失调细胞周期的可能性。
Cell cycle gene expression programs fuel proliferation and are universally dysregulated in cancer. The retinoblastoma (RB)-family of proteins, RB1, RBL1/p107, and RBL2/p130, coordinately represses cell cycle gene expression, inhibiting proliferation, and suppressing tumorigenesis. Phosphorylation of RB-family proteins by cyclin-dependent kinases is firmly established. Like phosphorylation, ubiquitination is essential to cell cycle control, and numerous proliferative regulators, tumor suppressors, and oncoproteins are ubiquitinated. However, little is known about the role of ubiquitin signaling in controlling RB-family proteins. A systems genetics analysis of CRISPR/Cas9 screens suggested the potential regulation of the RB-network by cyclin F, a substrate recognition receptor for the SCF family of E3 ligases. We demonstrate that RBL2/p130 is a direct substrate of SCFcyclin F. We map a cyclin F regulatory site to a flexible linker in the p130 pocket domain, and show that this site mediates binding, stability, and ubiquitination. Expression of a mutant version of p130, which cannot be ubiquitinated, severely impaired proliferative capacity and cell cycle progression. Consistently, we observed reduced expression of cell cycle gene transcripts, as well a reduced abundance of cell cycle proteins, analyzed by quantitative, iterative immunofluorescent imaging. These data suggest a key role for SCFcyclin F in the CDK-RB network and raise the possibility that aberrant p130 degradation could dysregulate the cell cycle in human cancers.