泛素特异性蛋白酶14的研究进展

泛素特异性蛋白酶14(ubiquitin-specific protease 14,USP14)是真核生物体内普遍存在的一种去泛素化酶,在编辑泛素链长度以及维持游离泛素库的稳定中发挥重要作用。它既可通过去泛素化调控靶蛋白的降解,又可通过多种信号通路参与肿瘤以及神经系统疾病的发生发展,因此USP14有望成为相关疾病治疗的极具潜力的新靶点。文章将从结构、功能、底物蛋白、信号通路、相关疾病以及抑制剂等方面对USP14的研究进展做一综述。     

泛素特异性蛋白酶在肿瘤发生发展中的作用

蛋白质泛素化修饰是细胞内关键的翻译后调控过程,能调节蛋白质的稳定性和功能。泛素特异性肽酶(ubiquitin-specific peptidases, USPs)是去泛素化酶家族的主要成员,能够识别特定蛋白质的泛素化信号,从而使靶蛋白去泛素化,进而参与细胞增殖、分化、凋亡和迁移等多种生物学功能。USP家族的多个成员表达量改变或活性异常与肿瘤的发生与发展密切相关,USPs被用于肿瘤新型分子诊断标志物和治疗靶点。本综述对USPs在肿瘤发生发展中的作用进行阐述,为肿瘤的诊断和靶向治疗奠定基础。     

去泛素化酶USP1的结构、功能及其抑制剂的研究进展

泛素化是一种维持细胞稳态必不可少的翻译后修饰,通过泛素分子与靶蛋白的连接参与蛋白质功能、定位和转换的调节。去泛素化酶介导的去泛素化为泛素化过程的逆反应,参与泛素的回收、编辑和重排。泛素特异性蛋白酶是最大的去泛素化酶家族,泛素特异性蛋白酶1 (USP1)是其中重要的亚型,广泛参与维持基因组完整性、细胞周期和细胞稳态。在多种肿瘤类型中均存在USP1异常表达,因此该靶点受到了广泛关注。目前研发进展最快的小分子USP1抑制剂为KSQ-4279,处于Ⅰ期临床研究阶段;另外ISM3091也已在国内和美国获得新药临床试验批件,即将开展临床试验。该文综述了USP1的结构、调控、生理功能、与肿瘤发生发展的关系以及USP1抑制剂的研究进展。     

去泛素化酶USP14的功能及其抑制剂的研究进展

去泛素化酶USP14(ubiquitin-specific proteases 14)属于去泛素化酶(deubiquitinating enzymes,DUBs)中的泛素特异性蛋白酶家族(ubiquitin-specific proteases,USPs),其可以切除底物的泛素链,并发挥相应的生物学效应。USP14在信号通路转导、病毒感染的调节、神经系统功能以及肿瘤发生发展进程中均起着重要作用。因其在肿瘤发展中的重要作用以及作为药靶的可行性,当前已经有很多研究将USP14的抑制剂作为抗肿瘤药物研究的新方向。主要综述了USP14在信号通路、病毒感染、神经系统、肿瘤发展中的作用以及其抑制剂的研究进展。     

去泛素化酶USP10通过稳定Smurf1抑制TGF-β/BMP信号通路

目的 探究生理条件下去泛素化酶USP10调控的关键信号通路及分子机制。方法 利用GEO2R和Metascape对Usp10^+/+和Usp10^-/-新生小鼠肾组织基因芯片(GSE198574)差异表达基因和通路富集分析，使用免疫印迹实验和免疫组化技术检验核心转录因子的表达情况；进一步利用免疫印迹检测该信号通路，并通过基因芯片和免疫组化分析候选分子的表达情况；使用免疫共沉淀(Co-IP)和GST-pull down实验验证USP10与候选分子的相互作用，通过泛素化实验明确USP10对底物分子的调控机制；利用免疫印迹检测细胞增殖、凋亡相关蛋白p21、Cleaved-caspase 3的表达情况，使用CCK-8和克隆形成实验分析USP10对细胞增殖的影响。结果 Usp10^-/-新生小鼠肾组织中TGF-β/BMP通路激活，USP10在小鼠体内缺失后导致Smad泛素相关因子1 (Smurf1)蛋白质水平降低，Smad1/5蛋白质水平上调，却不影响它们的转录水平；机制上，USP10与Smurf1存在相互作用，并依赖其去泛素化酶活性去除...     

USP22在转录调控及肿瘤发生中的作用

泛素特异性蛋白酶22（ubiquitin specific protease 22,USP22）是一种组蛋白去泛素化酶,在核受体介导的基因转录调控中起增强转录活性的作用。USP22在肿瘤发生、发展中发挥着重要作用,影响癌基因c-Myc介导的基因转录,从而促进肿瘤的增殖和生长;另一方面,USP22可改变远上游识别序列结合蛋白1（far upstream element—binding protein1,FBP1）的泛素化水平,从而影响FBP1下游的抑癌基因p21的表达。USP22与胃癌、大肠癌、乳腺癌及膀胱癌等肿瘤的病理进程相关。此外,USP22在端粒稳态的维持中起作用。本文主要综述USP22参与核受体介导的基因转录调控的表观遗传学机制及其在肿瘤发生中的作用。     

USP18介导的蛋白质去ISG化及其在结核病等传染病中的作用

干扰素诱导基因15 (interferon-stimulated gene 15,isg15)的表达受Ⅰ型干扰素诱导,该基因编码的蛋白ISG15可以分别通过E1、E2和E3酶的作用共价修饰靶蛋白,此过程被称为ISG化(ISGylation)。宿主蛋白的ISG化广泛参与天然免疫例如宿主的抗病毒过程。泛素特异性蛋白酶18 (ubiquitin-specific protease 18,USP18)作为一种去泛素化酶(deubiquitinase,DUB)可以去除靶蛋白偶联的ISG15,并通过抑制Ⅰ型干扰素信号通路来抑制宿主的免疫应答。ISG15介导的ISG化和USP18介导的去ISG化(deISGylation)建立的动态平衡对结核病的发生、发展和转归有重要影响。此外,同ISG15一样,USP18也广泛参与病毒感染和宿主细胞抗病毒反应,多种先天性免疫疾病和免疫信号通路都受到USP18的调节。本文综述了ISG15和USP18相关的研究进展,重点介绍了ISG15介导的ISGylation和USP18介导的去ISG化在结核病及其他重要疾病中的调控作用,以期为靶向宿主蛋白的结核病等重要疾病防治提供...     

去泛素化酶与肿瘤

泛素化修饰（ubiquitination modification）广泛存在于真核生物,通过26S蛋白酶体降解途径或信号传递等,改变蛋白质稳定性、定位和活性等功能,参与细胞的周期、转录、炎症、肿瘤和免疫等各项功能,是一类复杂的动态调控系统。泛素化调节是一个可逆过程,被泛素连接酶（ubiquitin ligase,E3）和去泛素化酶（deubiquitylase,DUB）拮抗调控。去泛素化酶可介导底物蛋白质去泛素化,调节蛋白质功能,参与细胞各项生命活动。去泛素化酶的蛋白质丰度、定位和催化活性等受到严格调控。在肿瘤的发生发展过程中,有许多与肿瘤相关的重要抑癌或者促癌蛋白质被去泛素化酶调控,而且去泛素化酶的表达异常、突变等都会影响细胞的DNA损伤修复、凋亡、自噬、分子信号通路和染色质重塑等,从而调控肿瘤细胞的生长侵袭和转移等过程。因此,去泛素化酶系统是参与肿瘤调控的重要蛋白质,也是肿瘤的重要药物靶标,已有多个小分子抑制剂用于抗肿瘤治疗的研发。本文主要总结介绍了泛素分子、泛素链特异性和去泛素化酶系统在肿瘤中的调节机制,为临床药物靶点的设计以及诊断指标等提供依据。     

泛素链水解酶的选择性和产生机制

底物蛋白的多聚泛素链修饰参与调节多种生命运动过程(包括蛋白质降解、自噬、DNA损伤修复、细胞周期、信号转导、基因表达、转录调节、炎症免疫等).去泛素化酶通过水解底物蛋白的单泛素和泛素链修饰,对泛素相关过程进行反向调节.人类基因组中约含90余种去泛素化酶,它们通过对自身酶活性和底物识别特异性的调节,实现了对细胞内复杂泛素过程的精密且层次性的调控.本文针对去泛素化酶对不同泛素链的识别选择性,综述目前已知泛素链水解酶的选择性和产生机制.     

去泛素化酶与伴侣分子互作的病理生理及研究进展

去泛素化酶(DUBs)通过逆转泛素激活酶(E1)-泛素结合酶(E2)-泛素连接酶(E3)介导的泛素化过程,参与包括DNA复制、DNA损伤修复、炎症、贫血、凋亡、内吞等机体的生理病理过程。USP52,USP25,USP19属DUBs中的泛素特异性水解酶家族(USPs),与不同的伴侣分子相关联,USP52可去泛素化伴侣分子ASF1A,促进组蛋白H3-H4二聚体入核和DNA复制、修复顺利进行,两者高表达可使肿瘤的增殖能力和DNA损伤耐受性增强。USP52(别名PAN2)又可与PAN3形成复合物参与mRNA的代谢。牛痘相关激酶(VRK2)调节USP25的活性,影响后者对伴侣分子TRiC的稳定性,进而影响蛋白错误折叠。USP19(b亚型)和Hsp90,CHIP(E3连接酶)形成复合物调节错误折叠蛋白的命运。本文系统综述了去泛素化酶(DUBs)家族相关成员及其通过与伴侣分子相互作用在肿瘤等疾病的发生发展中所起的作用及其相关研究进展。     

Beclin1 controls the levels of p53 by regulating the deubiquitination activity of USP10 and USP13

Autophagy is an important intracellular catabolic mechanism that mediates the degradation of cytoplasmic proteins and organelles. We report a potent small molecule inhibitor of autophagy named "spautin-1" for specific and potent autophagy inhibitor-1. Spautin-1 promotes the degradation of Vps34 PI3 kinase complexes by inhibiting two ubiquitin-specific peptidases, USP10 and USP13, that target the Beclin1 subunit of Vps34 complexes. Beclin1 is a tumor suppressor and frequently monoallelically lost in human cancers. Interestingly, Beclin1 also controls the protein stabilities of USP10 and USP13 by regulating their deubiquitinating activities. Since USP10 mediates the deubiquitination of p53, regulating deubiquitination activity of USP10 and USP13 by Beclin1 provides a mechanism for Beclin1 to control the levels of p53. Our study provides a molecular mechanism involving protein deubiquitination that connects two important tumor suppressors, p53 and Beclin1, and a potent small molecule inhibitor of autophagy as a possible lead compound for developing anticancer drugs.     

USP2a protein deubiquitinates and stabilizes the circadian protein CRY1 in response to inflammatory signals

The mammalian circadian clock coordinates various physiological activities with environmental cues to achieve optimal adaptation. The clock manifests oscillations of key clock proteins, which are under dynamic control at multiple post-translational levels. As a major post-translational regulator, the ubiquitination-dependent proteasome degradation system is counterbalanced by a large group of deubiquitin proteases with distinct substrate preference. Until now, whether deubiquitination by ubiquitin-specific proteases can regulate the clock protein stability and circadian pathways remains largely unclear. The mammalian clock protein, cryptochrome 1 (CRY1), is degraded via the FBXL3-mediated ubiquitination pathway, suggesting that it is also likely to be targeted by the deubiquitination pathway. Here, we identified that USP2a, a circadian-controlled deubiquitinating enzyme, interacts with CRY1 and enhances its protein stability via deubiquitination upon serum shock. Depletion of Usp2a by shRNA greatly enhances the ubiquitination of CRY1 and dampens the oscillation amplitude of the CRY1 protein during a circadian cycle. By stabilizing the CRY1 protein, USP2a represses the Per2 promoter activity as well as the endogenous Per2 gene expression. We also demonstrated that USP2a-dependent deubiquitination and stabilization of the CRY1 protein occur in the mouse liver. Interestingly, the pro-inflammatory cytokine, TNF-α, increases the CRY1 protein level and inhibits circadian gene expression in a USP2a-dependent fashion. Therefore, USP2a potentially mediates circadian disruption by suppressing the CRY1 degradation during inflammation.     

Regulating the regulator: negative regulation of Cbl ubiquitin ligases

Cbl proteins are regulators of signal transduction through many pathways and, consequently, regulate cell function and development. They are ubiquitin ligases that ubiquitinate and target many signaling molecules for degradation. The Cbl proteins themselves are regulated by an increasingly complex network of interactions that fine-tune the effects that Cbl proteins have on signaling. The negative regulation of Cbl protein function can occur via cis-acting structural elements that prevent inappropriate ubiquitin ligase activity, degradation of the Cbl proteins, inhibition without degradation owing to interaction with other signaling proteins, deubiquitination of Cbl substrates, and regulation of assembly of the endosomal ESCRT-I complex. Defects in the regulatory mechanisms that control Cbl function are implicated in the development of immunological and malignant diseases.     

Deubiquitinase inhibitor degrasyn suppresses metastasis by targeting USP5‐WT1‐E‐cadherin signalling pathway in pancreatic ductal adenocarcinoma

Wilm's tumour‐1 (WT1) is overexpressed in pancreatic ductal adenocarcinoma (PDAC) and enhances metastasis. Deubiquitination stabilizes target proteins, and inhibiting deubiquitination facilitates the degradation of target proteins. However, whether inhibiting deubiquitination of WT1 facilitates its degradation and presents anti‐cancer ability in PDAC is unknown. Here, we found that deubiquitinase inhibitor degrasyn rapidly induced the degradation of endogenous and exogenous WT1 through enhancing ubiquitination of WT1 followed by the up‐regulation of E‐cadherin. Knockdown of WT1 by short hairpin RNAs (shRNAs) inhibited metastasis and overexpression of WT1 partially prevented degrasyn‐induced anti‐metastasis activity, suggesting that degrasyn presents anti‐metastasis activity partially through degrading WT1 protein. We further identified that USP5 deubiquitinated WT1 and stabilized its expression. The higher expressions of USP5 and WT1 are associated with tumour metastasis. More importantly, degrasyn inhibited the activity of USP5 and overexpression of USP5 partially prevented degrasyn‐induced degradation of WT1 protein, suggesting that degrasyn degraded WT1 protein through inhibiting the activity of USP5. Finally, degrasyn reduced the tumorigenicity in a xenograft mouse model and reduced the metastasis in vivo. Our results indicate that degrasyn presents strong anti‐cancer activity through USP5‐WT1‐E‐cadherin signalling in PDAC. Therefore, degrasyn holds promise as cancer therapeutic agent in PDAC with high expressions of USP5 and WT1.     

USP39-mediated deubiquitination of Cyclin B1 promotes tumor cell proliferation and glioma progression

BackgroundThe elevated Cyclin B1 expression contributes to various tumorigenesis and poor prognosis. Cyclin B1 expression could be regulated by ubiquitination and deubiquitination. However, the mechanism of how Cyclin B1 is deubiquitinated and its roles in human glioma remain unclear.MethodsCo-immunoprecipitation and other assays were performed to detect the interacting of Cyclin B1 and USP39. A series of in vitro and in vivo experiments were performed to investigate the effect of USP39 on the tumorigenicity of tumor cells.ResultsUSP39 interacts with Cyclin B1 and stabilizes its expression by deubiquitinating Cyclin B1. Notably, USP39 cleaves the K29-linked polyubiquitin chain on Cyclin B1 at Lys242. Additionally, overexpression of Cyclin B1 rescues the arrested cell cycle at G2/M transition and the suppressed proliferation of glioma cells caused by USP39 knockdown in vitro. Furthermore, USP39 promotes the growth of glioma xenograft in subcutaneous and in situ of nude mice. Finally, in human tumor specimens, the expression levels of USP39 and Cyclin B1 are positively relevant.ConclusionOur data support the evidence that USP39 acts a novel deubiquitinating enzyme of Cyclin B1 and promoted tumor cell proliferation at least in part through Cyclin B1 stabilization, represents a promising therapeutic strategy for tumor patients.     

Regulation of mitochondrial morphology by USP30, a deubiquitinating enzyme present in the mitochondrial outer membrane

Recent studies have suggested that ubiquitination of mitochondrial proteins participates in regulating mitochondrial dynamics in mammalian cells, but it is unclear whether deubiquitination is involved in this process. Here, we identify human ubiquitin-specific protease 30 (USP30) as a deubiquitinating enzyme that is embedded in the mitochondrial outer membrane. Depletion of USP30 expression by RNA interference induced elongated and interconnected mitochondria, depending on the activities of the mitochondrial fusion factors mitofusins, without changing the expression levels of the key regulators for mitochondrial dynamics. Mitochondria were rescued from this abnormal phenotype by ectopic expression of USP30 in a manner dependent on its enzymatic activity. Our findings reveal that USP30 participates in the maintenance of mitochondrial morphology, a finding that provides new insight into the cellular function of deubiquitination.     

Deubiquitination of Chfr, a checkpoint protein, by USP7/HAUSP regulates its stability and activity

Chfr, a mitotic stress checkpoint, plays an important role in cell cycle progression, tumor suppression and the processes that require the E3 ubiquitin ligase activity mediated by the RING finger domain. Chfr stimulates the formation of polyubiquitin chains by ub-conjugating enzymes, and induces the proteasome-dependent degradation of a number of cellular proteins including Plk1 and Aurora A. In this study, we identified USP7 (also known as HAUSP), which is a member of a family of proteins that cleave polyubiquitin chains and/or ubiquitin precursors, as an interacting protein with Chfr by immunoaffinity purification and mass spectrometry, and their interaction greatly increases the stability of Chfr. In fact, USP7 can remove ubiquitin moiety from the autoubiquitinated Chfr both in vivo and in vitro, which results in the accumulation of Chfr in the cell. Thus, our finding suggests that USP7-mediated deubiquitination of Chfr leads to its accumulation, which might be a key regulatory step for Chfr activation and that USP7 may play an important role in the regulation of Chfr-mediated cellular processes including cell cycle progression and tumor suppression.     

肿瘤抑制因子CYLD对细胞功能的调控作用

肿瘤抑制因子（cylindromatosis,CYLD）是一种在体内广泛分布的去泛素酶,其包含去泛素化酶结构域和富含甘氨酸细胞骨架相关蛋白结构域,前者可通过去泛素化信号分子,调控细胞信号传导途径,后者主要通过对微管的调节,改变多聚化和乙酰化过程,进而调控其组装和排列。CYLD主要通过对信号传导和细胞骨架的调节,从而调控细胞增殖、细胞凋亡、细胞运动和细胞分化等细胞功能。该文对近年来肿瘤抑制因子CYLD对细胞功能调控的研究进行概述。