Inhibition of Ubiquitin-specific Protease 4 Attenuates Epithelial-Mesenchymal Transition of Renal Tubular Epithelial Cells via Transforming Growth Factor Beta Receptor Type Ⅰ

Objective Ubiquitin-specific protease 4(USP4)facilitates the development of transforming growth factor-beta 1(TGF-β1)-induced epithelial-mesenchymal transition(EMT)in various cancer cells.Moreover,EMT of renal tubular epithelial cells(RTECs)is required for the progression of renal interstitial fibrosis.However,the role of USP4 in EMT of RTECs remains unknown.The present study aimed to explore the effect of USP4 on the EMT of RTECs as well as the involved mechanism.Methods In established unilateral ureteral obstruction(UUO)rats and NRK-52E cells,immunohistochemistry and Western blot assays were performed.Results USP4 expression was increased significantly with obstruction time.In NRK-52E cells stimulated by TGF-β1,USP4 expression was increased in a time-dependent manner.In addition,USP4 silencing with specific siRNA indicated that USP4 protein was suppressed effectively.Meanwhile,USP4 siRNA treatment restored E-cadherin and weakened alpha smooth muscle actin(α-SMA)expression,indicating that USP4 may promote EMT.After treatment with USP4 siRNA and TGF-β1 for 24 h,the expression of TGF-β1 receptor type I(TβRI)was decreased.Conclusion USP4 promotes the EMT of RTECs through upregulating TβRI,thereby facilitating renal interstitial fibrosis.These findings may provide a potential target of USP4 in the treatment of renal fibrosis.

Emerging potential of ubiquitin-specific proteases and ubiquitinspecific proteases inhibitors in breast cancer treatment

Breast cancer is the most frequently diagnosed cancer in women,accounting for 30%of new diagnosing female cancers.Emerging evidence suggests that ubiquitin and ubiquitination played a role in a number of breast cancer etiology and progression processes.As the primary deubiquitinases in the family,ubiquitin-specific peptidases(USPs)are thought to represent potential therapeutic targets.The role of ubiquitin and ubiquitination in breast cancer,as well as the classification and involvement of USPs are discussed in this review,such as USP1,USP4,USP7,USP9X,USP14,USP18,USP20,USP22,USP25,USP37,and USP39.The reported USPs inhibitors investigated in breast cancer were also summarized,along with the signaling pathways involved in the investigation and its study phase.Despite no USP inhibitor has yet been approved for clinical use,the biological efficacy indicated their potential in breast cancer treatment.With the improvements in phenotypic discovery,we will know more about USPs and USPs inhibitors,developing more potent and selective clinical candidates for breast cancer.

Ubiquitin-specific protease 24 promotes EV71 infection by restricting K63-linked polyubiquitination of TBK1

TANK-binding kinase 1(TBK1)is an essential protein kinase for activation of interferon regulatory factor 3(IRF3)and induction of the type I interferons(IFN-I).Although the biochemical regulation of TBK1 activation has been studied,little is known about how enterovirus 71(EV71)employs the deubiquitinases(DUBs)to regulate TBK1 activation for viral immune evasion.Here,we found that EV71 infection upregulated the expression of ubiquitinspecific protease 24(USP24).Further studies revealed that USP24 physically interacted with TBK1,and can reduce K63-linked polyubiquitination of TBK1.Knockdown of USP24 upregulated TBK1 K63-linked polyubiquitination,promoted the phosphorylation and nuclear translocation of IRF3,and in turn improved IFN-I production during EV71 infection.As a consequence,USP24 knockdown dramatically inhibited EV71 infection.This study revealed USP24 as a novel regulator of TBK1 activation,which promotes the understanding of immune evasion mechanisms of EV71 and could provide a potential strategy for treatment of EV71 infection.

The expression of Usp26 gene in mouse testis and brain

Deubiquitinating enzymes （DUBs） play an important role in ubiquitin-dependent processes as negative regulators of protein ubiquitination. Ubiquitin-specific protease 26 （USP26） is a member of this family. The expression of Usp26 in mammalian testis and in other tissues has yet to be fully elucidated. To study the expression of Usp26 mRNA and protein in various murine tissues, reverse transcription （RT）-PCR and immunohistochemistry analyses were carried out. The RT-PCR analysis showed that the Usp26 transcript was expressed in all of the tested tissues. USP26 protein localization was examined by immunohistochemistry, and it was shown that USP26 was not detectable at 20 days postpartum, with the expression restricted to the cytoplasm of condensing spermatids （steps 9-16）, Leydig cells and nerve fibers in the brain. In addition, the USP26 protein was detected at moderate levels in myocardial ceils, the corpus of epidydimis, epithelium of the renal tubules and the seminal gland of postnatal day 35 mice. Its spatial and temporal expression pattern suggests that Usp26 may play an important role in development or function of the testis and brain. Further research into these possibilities is in progress.

Cardiac fibroblast heat shock protein 47 aggravates cardiac fibrosis post myocardial ischemia-reperfusion injury by encouraging ubiquitin specific peptidase 10 dependent Smad4 deubiquitination

Despite complications were significantly reduced due to the popularity of percutaneous coronary intervention(PCI) in clinical trials, reperfusion injury and chronic cardiac remodeling significantly contribute to poor prognosis and rehabilitation in AMI patients. We revealed the effects of HSP47 on myocardial ischemia-reperfusion injury(IRI) and shed light on the underlying molecular mechanism.We generated adult mice with lentivirus-mediated or miRNA(mi1/133TS)-aided cardiac fibroblastselective HSP47 overexpression. Myocardial IRI was induced by 45-min occlusion of the left anterior descending(LAD) artery followed by 24 h reperfusion in mice, while ischemia-mediated cardiac remodeling was induced by four weeks of reperfusion. Also, the role of HSP47 in fibrogenesis was evaluated in cardiac fibroblasts following hypoxia-reoxygenation(HR). Extensive HSP47 was observed in murine infarcted hearts, human ischemic hearts, and cardiac fibroblasts and accelerated oxidative stress and apoptosis after myocardial IRI. Cardiac fibroblast-selective HSP47 overexpression exacerbated cardiac dysfunction caused by chronic myocardial IRI and presented deteriorative fibrosis and cell proliferation.HSP47 upregulation in cardiac fibroblasts promoted TGFβ1-Smad4 pathway activation and Smad4 deubiquitination by recruiting ubiquitin-specific peptidase 10(USP10) in fibroblasts. However, cardiac fibroblast specific USP10 deficiency abolished HSP47-mediated fibrogenesis in hearts. Moreover, blockage of HSP47 with Col003 disturbed fibrogenesis in fibroblasts following HR. Altogether, cardiac fibroblast HSP47 aggravates fibrosis post-myocardial IRI by enhancing USP10-dependent Smad4 deubiquitination,which provided a potential strategy for myocardial IRI and cardiac remodeling.