IDI IRCCS Biochemistry Laboratory, Department of Experimental Medicine and Biochemical Sciences, University of Rome Tor Vergata, Rome, Italy.
Oncogene. 2010 Mar 4;29(9):1384-93. doi: 10.1038/onc.2009.430. Epub 2009 Dec 7.
Ubiquitin-specific proteases (USPs) are a subclass of cysteine proteases that catalyze the removal of ubiquitin (either monomeric or chains) from substrates, thus counteracting the activity of E3 ubiquitin ligases. Although the importance of USPs in a multitude of processes, from hereditary cancer to neurodegeneration, is well established, our knowledge on their mode of regulation, substrate specificity and biological function is quite limited. In this study we identify USP47 as a novel interactor of the E3 ubiquitin ligase, Skp1/Cul1/F-box protein beta-transducin repeat-containing protein (SCF(beta-Trcp)). We found that both beta-Trcp1 and beta-Trcp2 bind specifically to USP47, and point mutations in the beta-Trcp WD-repeat region completely abolished USP47 binding, indicating an E3-substrate-type interaction. However, unlike canonical beta-Trcp substrates, USP47 protein levels were neither affected by silencing of beta-Trcp nor modulated in a variety of processes, such as cell-cycle progression, DNA damage checkpoint responses or tumor necrosis factor (TNF) pathway activation. Notably, genetic or siRNA-mediated depletion of USP47 induced accumulation of Cdc25A, decreased cell survival and augmented the cytotoxic effects of anticancer drugs. In conclusion, we showed that USP47, a novel beta-Trcp interactor, regulates cell growth and survival, potentially providing a novel target for anticancer therapies.
泛素特异性蛋白酶（USPs）是半胱氨酸蛋白酶的一个亚类，能催化从底物上移除泛素（不论是单体或是多聚体），从而抵消 E3 泛素连接酶的活性。尽管 USPs 在从遗传性癌症到神经退行性疾病等多种过程中的重要性已得到充分证实，但我们对其调控方式、底物特异性和生物学功能的了解相当有限。在这项研究中，我们鉴定出 USP47 是 E3 泛素连接酶 Skp1/Cul1/F-box 蛋白β-转化重复蛋白（SCF（β-Trcp）的一个新的相互作用蛋白。我们发现β-Trcp1 和β-Trcp2 都能特异性地与 USP47 结合，而β-Trcp WD 重复区的点突变完全消除了 USP47 的结合，表明这是一种 E3-底物类型的相互作用。然而，与典型的β-Trcp 底物不同，USP47 蛋白水平既不受β-Trcp 沉默的影响，也不受细胞周期进程、DNA 损伤检查点反应或肿瘤坏死因子（TNF）途径激活等多种过程的调节。值得注意的是，USP47 的遗传或 siRNA 介导耗竭导致 Cdc25A 的积累增加、细胞存活率降低，并增强了抗癌药物的细胞毒性作用。总之，我们表明 USP47 作为一种新的β-Trcp 相互作用蛋白，调节细胞生长和存活，可能为抗癌治疗提供了一个新的靶点。
