Comprehensive analysis of the role of ubiquitin-specific peptidases in colorectal cancer:A systematic review

BACKGROUND Colorectal cancer(CRC)is the third most frequent and the second most fatal cancer.The search for more effective drugs to treat this disease is ongoing.A better understanding of the mechanisms of CRC development and progression may reveal new therapeutic strategies.Ubiquitin-specific peptidases(USPs),the largest group of the deubiquitinase protein family,have long been implicated in various cancers.There have been numerous studies on the role of USPs in CRC;however,a comprehensive view of this role is lacking.AIM To provide a systematic review of the studies investigating the roles and functions of USPs in CRC.METHODS We systematically queried the MEDLINE(via PubMed),Scopus,and Web of Science databases.RESULTS Our study highlights the pivotal role of various USPs in several processes implicated in CRC:Regulation of the cell cycle,apoptosis,cancer stemness,epithelial–mesenchymal transition,metastasis,DNA repair,and drug resistance.The findings of this study suggest that USPs have great potential as drug targets and noninvasive biomarkers in CRC.The dysregulation of USPs in CRC contributes to drug resistance through multiple mechanisms.CONCLUSION Targeting specific USPs involved in drug resistance pathways could provide a novel therapeutic strategy for overcoming resistance to current treatment regimens in CRC.

Deubiquitinase JOSD2 stabilizes YAP/TAZ to promote cholangiocarcinoma progression

Cholangiocarcinoma(CCA)has emerged as an intractable cancer with scanty therapeutic regimens.The aberrant activation of Yes-associated protein(YAP)and transcriptional co-activator with PDZ-binding motif(TAZ)are reported to be common in CCA patients.However,the underpinning mechanism remains poorly understood.Deubiquitinase(DUB)is regarded as a main orchestrator in maintaining protein homeostasis.Here,we identified Josephin domain-containing protein 2(JOSD2)as an essential DUB of YAP/TAZ that sustained the protein level through cleavage of polyubiquitin chains in a deubiquitinase activity-dependent manner.The depletion of JOSD2 promoted YAP/TAZ proteasomal degradation and significantly impeded CCA proliferation in vitro and in vivo.Further analysis has highlighted the positive correlation between JOSD2 and YAP abundance in CCA patient samples.Collectively,this study uncovers the regulatory effects of JOSD2 on YAP/TAZ protein stabilities and profiles its contribution in CCA malignant progression,which may provide a potential intervention target for YAP/TAZ-related CCA patients.

The function and regulation of OTU deubiquitinases

Post-translational modification of cellular proteins by ubiquitin regulates numerous cellular processes,including cell division,immune responses,and apoptosis.Ubiquitin-mediated control over these processes can be reversed by deubiquitinases(DUBs),which remove ubiquitin from target proteins and depolymerize polyubiquitin chains.Recently,much progress has been made in the DUBs.In humans,the ovarian tumor protease(OTU)subfamily of DUBs includes 16 members,most of which mediate cell signaling cascades.These OTUs show great variation in structure and function,which display a series of mechanistic features.In this review,we provide a comprehensive analysis of current progress in character,structure and function of OTUs,such as the substrate specificity and catalytic activity regulation.Then we discuss the relationship between some diseases and OTUs.Finally,we summarize the structure of viral OTUs and their function in immune escape and viral survival.Despite the challenges,OTUs might provide new therapeutic targets,due to their involvement in key regulatory processes.

Semi-synthesis of Ubiquitin-propargylamide for identifying deubiquitinase targeting inhibitors

Ubiquitin-propargylamide(Ub-PA) is one of the most widely used activity-based probe to measure the activity of deubiquitinases(DUBs) and help validate DUBs targeting inhibitors. However, current synthetic route of Ub-PA is cumbersome. In this work, we report a novel semi-synthetic strategy to prepare Ub-PA in large-scale. Biochemical assays prove that semi-synthetic Ub-PA is an effective probe in identifying DUBs targeting inhibitors.

Blockade of deubiquitinase YOD1 degrades oncogenic PML/RARα and eradicates acute promyelocytic leukemia cells

In most acute promyelocytic leukemia(APL)cells,promyelocytic leukemia(PML)fuses to retinoic acid receptor α (RARα)due to chromosomal translocation,thus generating PML/RARαoncoprotein,which is a relatively stable oncoprotein for degradation in APL.Elucidating the mechanism regulating the stability of PML/RARαmay help to degrade PML/RARαand eradicate APL cells.Here,we describe a deubiquitinase(DUB)-involved regulatory mechanism for the maintenance of PML/RARαstability and develop a novel pharmacological approach to degrading PML/RARαby inhibiting DUB.We utilized a DUB siRNA library to identify the ovarian tumor protease(OTU)family member deubiquitinase YOD1 as a critical DUB of PML/RARα.Suppression of YOD1 promoted the degradation of PML/RARα,thus inhibiting APL cells and prolonging the survival time of APL cell-bearing mice.Subsequent phenotypic screening of small molecules allowed us to identify ubiquitin isopeptidase inhibitor I(G5)as the first YOD1 pharmacological inhibitor.As expected,G5 notably degraded PML/RARαprotein and eradicated APL,particularly drug-resistant APL cells.Importantly,G5 also showed a strong killing effect on primary patient-derived APL blasts.Overall,our study not only reveals the DUB-involved regulatory mechanism on PML/RARαstability and validates YOD1 as a potential therapeutic target for APL,but also identifies G5 as a YOD1 inhibitor and a promising candidate for APL,particularly drug-resistant APL treatment.

Regulation of antiviral innate immunity by deubiquitinase CYLD

An antiviral innate immune response involves induction of type I interferons(IFNs)and their subsequent autocrine and paracrine actions,but the underlying regulatory mechanisms are incompletely understood.Here we report that CYLD,a deubiquitinase that specifically digests lysine 63-linked ubiquitin chains,is required for antiviral host defense.Loss of CYLD renders mice considerably more susceptible to infection by vesicular stomatitis virus(VSV).Consistently,CYLD-deficient dendritic cells are more sensitive to VSV infection.This functional defect was not due to lack of type I IFN production but rather because of attenuated IFN receptor signaling.In the absence of CYLD,IFN-b is ineffective in the induction of antiviral genes and protection of cells from viral infection.These findings establish CYLD as a novel regulator of antiviral innate immunity and suggest a role for CYLD in regulating IFN receptor signaling.

Deubiquitinase ubiquitin-specific protease 3 (USP3) inhibits HIV-1 replication via promoting APOBEC3G (A3G) expression in both enzyme activity-dependent and -independent manners

Background: Ubiquitination plays an essential role in many biological processes, including viral infection, and can be reversed by deubiquitinating enzymes (DUBs). Although some studies discovered that DUBs inhibit or enhance viral infection by various mechanisms, there is lack of information on the role of DUBs in virus regulation, which needs to be further investigated.Methods: Immunoblotting, real-time polymerase chain reaction,in vivo/in vitro deubiquitination, protein immunoprecipitation, immunofluorescence, and co-localization biological techniques were employed to examine the effect of ubiquitin-specific protease 3 (USP3) on APOBEC3G (A3G) stability and human immunodeficiency virus (HIV) replication. To analyse the relationship between USP3 and HIV disease progression, we recruited 20 HIV-infected patients to detect the levels of USP3 and A3G in peripheral blood and analysed their correlation with CD4^(+) T-cell counts. Correlation was estimated by Pearson correlation coefficients (for parametric data).Results: The results demonstrated that USP3 specifically inhibits HIV-1 replication in an A3G-dependent manner. Further investigation found that USP3 stabilized 90% to 95% of A3G expression by deubiquitinating Vif-mediated polyubiquitination and blocking its degradation in an enzyme-dependent manner. It also enhances the A3G messenger RNA (mRNA) level by binding to A3G mRNA and stabilizing it in an enzyme-independent manner. Moreover, USP3 expression was positively correlated with A3G expression (r= 0.5110) and CD4^(+) T-cell counts (r= 0.5083) in HIV-1-infected patients.Conclusions: USP3 restricts HIV-1 viral infections by increasing the expression of the antiviral factor A3G. Therefore, USP3 may be an important target for drug development and serve as a novel therapeutic strategy against viral infections.

Regulation of inflammasomes by ubiquitination

Inflammasomes 是由响应病原体暴露或细胞的损坏便于煽动性的 cytokines 的版本调整天生的有免疫力的反应的多蛋白质建筑群。支持 inflammatory inflammasome 发信号是重要的招待防卫，帮助开始跟随侮辱到主机，而是罐头的织物修理的进程有害，当过多或长期时。因此， inflammasome 活动紧被调整。这里，我们讨论 inflammasome 规定的一批评机制， ubiquitination，那作为蛋白质稳定性和 trafficking 的一个通用调节的人工作。最近的研究由蛋白质 ubiquitination 提供了重要卓见进 inflammasome 激活的规定。明确地，当它联系到 ubiquitination，我们考察 inflammasome 功能的分子的规定，并且讨论含意让治疗学的发展明确地指向异常 inflammasome 发信号。

How are MCPIP1 and cytokines mutually regulated in cancer-related immunity?

Cytokines are secreted by various cell types and act as critical mediators in many physiological processes,including immune response and tumor progression.Cytokines production is precisely and timely regulated by multiple mechanisms at different levels,ranging from transcriptional to post-transcriptional and posttranslational processes.Monocyte chemoattractant protein-1 induced protein 1(MCPIP1),a potent immunosuppressive protein,was first described as a transcription factor in monocytes treated with monocyte chemoattractant protein-1(MCP-1)and subsequently found to possess intrinsic RNase and deubiquitinase activities.MCPIP1 tightly regulates cytokines expression via various functions.Furthermore,cytokines such as interleukin 1 beta(IL-1B)and MCP-1 and inflammatory cytokines inducer lipopolysaccharide(LPS)strongly induce MCPIP1 expression.Mutually regulated MCPIP1 and cytokines form a complicated network in the tumor environment.In this review,we summarize how MCPIP1 and cytokines reciprocally interact and elucidate the effect of the network formed by these components in cancer-related immunity with aim of exploring potential clinical benefits of their mutual regulation.

The USP7 protein interaction network and its roles in tumorigenesis

Ubiquitin-specific protease(USP7),also known as Herpesvirus-associated ubiquitin-specific protease(HAUSP),is a deubiquitinase.There has been significant recent attention on USP7 following the discovery that USP7 is a key regulator of the p53-MDM2 pathway.The USP7 protein is 130 kDa in size and has multiple domains which bind to a diverse set of proteins.These interactions mediate key developmental and homeostatic processes including the cell cycle,immune response,and modulation of transcription factor and epigenetic regulator activity and localization.USP7 also promotes carcinogenesis through aberrant activation of the Wnt signalling pathway and stabilization of HIF-1α.These findings have shown that USP7 may induce tumour progression and be a therapeutic target.Together with interest in developing USP7 as a target,several studies have defined new protein interactions and the regulatory networks within which USP7 functions.In this review,we focus on the protein interactions of USP7 that are most important for its cancer-associated roles.

Structural and mutational analysis of the interaction between the Middle-East respiratory syndrome coronavirus (MERS-CoV) papain-like protease and human ubiquitin

The papain-like protease(PL^(pro)) of Middle-East respiratory syndrome coronavirus(MERS-CoV) has proteolytic,deubiquitinating,and de ISGylating activities.The latter two are involved in the suppression of the antiviral innate immune response of the host cell.To contribute to an understanding of this process,we present here the X-ray crystal structure of a complex between MERS-CoV PL^(pro) and human ubiquitin(Ub) that is devoid of any covalent linkage between the two proteins.Five regions of the PL^(pro) bind to two areas of the Ub.The C-terminal five residues of Ub,RLRGG,are similar to the P5–P1 residues of the polyprotein substrates of the PL^(pro) and are responsible for the major part of the interaction between the two macromolecules.Through sitedirected mutagenesis,we demonstrate that conserved Asp165 and non-conserved Asp164 are important for the catalytic activities of MERS-CoV PL^(pro).The enzyme appears not to be optimized for catalytic efficiency; thus,replacement of Phe269 by Tyr leads to increased peptidolytic and deubiquitinating activities.Ubiquitin binding by MERS-CoV PL^(pro) involves remarkable differences compared to the corresponding complex with SARS-CoV PL^(pro).The structure and the mutational study help understand common and unique features of the deubiquitinating activity of MERS-CoV PL^(pro).

Regulation of the Hippo signaling pathway by deubiquitinating enzymes in cancer

Regulation of the Hippo signaling pathway is essential for normal organ growth and tissue homeostasis.The proteins that act to regulate this pathway are important for ensuring proper function and cellular location.Deubiquitinases(DUBs)are a family of proteases that act upon many proteins.While ubiquitinases add ubiquitin and target proteins for degradation,DUBs act by removing ubiquitin(Ub)moieties.Changes in ubiquitin chain topology results in the stabilization of proteins,membrane trafficking,and the alteration of cellular localization.While the roles of these proteins have been well established in a cancer setting,their convergence in cancer is still under investigation.In this review,we discuss the roles that DUBs play in the regulation of the Hippo signaling pathway for homeostasis and disease.