USP1 (ubiquitin specific peptidase 1)

Cancer Research, 2010

Ubiquitination is a reversible posttranslational modification that is essential for cell cycle control, and it is becoming increasingly clear that the removal of ubiquitin from proteins by deubiquitinating enzymes (DUB) is equally important. In this study, we have identified high levels of the DUB USP17 in several tumor-derived cell lines and primary lung, colon, esophagus, and cervix tumor biopsies. We also report that USP17 is tightly regulated during the cell cycle in all the cells examined, being abundantly evident in G 1 and absent in S phase. Moreover, regulated USP17 expression was necessary for cell cycle progression because its depletion significantly impaired G 1 -S transition and blocked cell proliferation. Previously, we have shown that USP17 regulates the intracellular translocation and activation of the GTPase Ras by controlling Ras-converting enzyme 1 (RCE1) activation. RCE1 also regulates the processing of other proteins with a CAAX motif, including Rho family GTPases. We now show that USP17 depletion blocks Ras and RhoA localization and activation. Moreover, our results confirm that USP17-depleted cells have constitutively elevated levels of the cyclin-dependent kinase inhibitors p21 cip1 and p27 kip1 , known downstream targets of Ras and RhoA signaling. These observations clearly show that USP17 is tightly regulated during cell division and that its expression is necessary to coordinate cell cycle progression, and thus, it may be considered a promising novel cancer therapeutic target.

Journal of Experimental & Clinical Cancer Research, 2021

Protein ubiquitination is one of the most crucial posttranslational modifications responsible for regulating the stability and activity of proteins involved in homeostatic cellular function. Inconsistencies in the ubiquitination process may lead to tumorigenesis. Ubiquitin-specific peptidases are attractive therapeutic targets in different cancers and are being evaluated for clinical development. Ubiquitin-specific peptidase 37 (USP37) is one of the least studied members of the USP family. USP37 controls numerous aspects of oncogenesis, including stabilizing many different oncoproteins. Recent work highlights the role of USP37 in stimulating the epithelial-mesenchymal transition and metastasis in lung and breast cancer by stabilizing SNAI1 and stimulating the sonic hedgehog pathway, respectively. Several aspects of USP37 biology in cancer cells are yet unclear and are an active area of research. This review emphasizes the importance of USP37 in cancer and how identifying its molecul...

Cells, 2024

This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Cell Death & Disease

Deubiquitination is now understood to be as important as its partner ubiquitination for the maintenance of protein half-life, activity, and localization under both normal and pathological conditions. The enzymes that remove ubiquitin from target proteins are called deubiquitinases (DUBs) and they regulate a plethora of cellular processes. DUBs are essential enzymes that maintain intracellular protein homeostasis by recycling ubiquitin. Ubiquitination is a post-translational modification where ubiquitin molecules are added to proteins thus influencing activation, localization, and complex formation. Ubiquitin also acts as a tag for protein degradation, especially by proteasomal or lysosomal degradation systems. With ~100 members, DUBs are a large enzyme family; the ubiquitin-specific peptidases (USPs) being the largest group. USP10, an important member of this family, has enormous significance in diverse cellular processes and many human diseases. In this review, we discuss recent st...

Frontiers in Cell and Developmental Biology, 2021

The deubiquitinating enzyme (DUB)–mediated cleavage of ubiquitin plays a critical role in balancing protein synthesis and degradation. Ubiquitin-specific protease 4 (USP4), a member of the largest subfamily of cysteine protease DUBs, removes monoubiquitinated and polyubiquitinated chains from its target proteins. USP4 contains a DUSP (domain in USP)–UBL (ubiquitin-like) domain and a UBL-insert catalytic domain, sharing a common domain organization with its paralogs USP11 and USP15. USP4 plays a critical role in multiple cellular and biological processes and is tightly regulated under normal physiological conditions. When its expression or activity is aberrant, USP4 is implicated in the progression of a wide range of pathologies, especially cancers. In this review, we comprehensively summarize the current knowledge of USP4 structure, biological functions, pathological roles, and cellular regulation, highlighting the importance of exploring effective therapeutic interventions to targe...

Journal of Biomedical Science, 2019

Protein ubiquitination is an important mechanism for regulating the activity and levels of proteins under physiological conditions. Loss of regulation by protein ubiquitination leads to various diseases, such as cancer. Two types of enzymes, namely, E1/E2/E3 ligases and deubiquitinases, are responsible for controlling protein ubiquitination. The ubiquitin-specific peptidases (USPs) are the main members of the deubiquitinase family. Many studies have addressed the roles of USPs in various diseases. An increasing number of studies have indicated that USPs are critical for cancer progression, and some USPs have been used as targets to develop inhibitors for cancer prevention. Herein we collect and organize most of the recent studies on the roles of USPs in cancer progression and discuss the development of USP inhibitors for cancer therapy in the future.

Scientific Reports, 2018

The ubiquitin specific protease, USP7, regulates multiple cellular pathways relevant for cancer through its ability to bind and sometimes stabilize specific target proteins through deubiquitylation. To gain a more complete profile of USP7 interactions in cancer cells, we performed affinity purification coupled to mass spectrometry to identify USP7 binding targets in gastric carcinoma cells. This confirmed reported associations of USP7 with USP11, PPM1G phosphatase and TRIP12 E3 ubiquitin ligase as well as identifying novel interactions with two DEAD/DEAH-box RNA helicases, DDX24 and DHX40. Using USP7 binding pocket mutants, we show that USP11, PPM1G, TRIP12 and DDX24 bind USP7 through its TRAF domain binding pocket, while DHX40 interacts with USP7 through a distinct binding pocket in the Ubl2 domain. P/A/ExxS motifs in USP11 and DDX24 that are critical for USP7 binding were also identified. Modulation of USP7 expression levels and inhibition of USP7 catalytic activity in multiple cells lines showed that USP7 consistently stabilizes DDX24, DHX40 and TRIP12 dependent on its catalytic activity, while USP11 and PPM1G levels were not consistently affected. Our study better defines the mechanisms of USP7 interaction with known targets and identifies DDX24 and DHX40 as new targets that are specifically bound and regulated by USP7. The turnover and function of many proteins is regulated by ubiquitylation, often leading to proteasomal degradation. Ubiquitin Specific Proteases (USPs) reverse this ubiquitylation resulting in protein stabilization. USP7 (also called HAUSP) has been shown to regulate the stability of a variety of cellular proteins playing important roles in DNA damage responses, apoptosis, immune responses, DNA replication and transcription 1-4. It is also a key regulator of the p53 pathway; binding and stabilizing the p53 E3 ubiquitin ligases Hdm2 and HdmX to downregulate p53 under normal growth conditions, but also binding and stabilizing p53 in response to DNA damage 5,6. In addition to its role in cleaving ubiquitin chains targeting proteins for degradation, USP7 can affect protein localization and function by reversing monoubiquitylation 7-10. Due to its multiple roles in processes that impact viral infection, USP7 is targeted by proteins from several DNA viruses, particularly herpesviruses, enabling these viruses to evade antiviral responses and replicate efficiently 9,11-22. USP7 has been shown to use two different binding pockets to recognize its target proteins, both of which are distinct from its central catalytic domain. The first binding pocket is within the N-terminal TRAF domain. This pocket was first identified as binding p53, Hdm2, Hdmx and the Epstein-Barr virus (EBV) EBNA1 protein 16,23-25 , and later shown to also mediate binding to minichromosome maintenance binding protein (MCM-BP) 26 , F-box protein FBXO38 27 , telomeric shelterin component TPP1 28 , ubiquitin E2 UbE2E1 29 and the vIRF1 and vIRF4 proteins of Kaposi's sarcoma associated herpesvirus (KSHV) 14,22. Structures and mutational analysis showed that a P/A/ExxS motif in all of these proteins mediated the interaction with the TRAF domain binding pocket and that USP7 amino acids D164 and W165 in this pocket are essential for mediating these interactions 16,22-26. The second binding pocket in USP7 is within one of the ubiquitin-like structures (Ubl2) in the C-terminal domain. This pocket is bound by GMP synthetase (GMPS), DNMT1, UHRF1, RNF169 and the herpes simplex virus 1 (HSV-1) protein ICP0, and involves an interaction of KxxxK motifs in these proteins with USP7 amino acids D762 and D764 30-35. Proteomic based studies on USP7 36 , as well as individual specific studies, have identified numerous proteins that bind USP7. However, in many cases the mechanism by which USP7 binds these proteins and whether or not this binding stabilizes these proteins has not been determined. For example, USP7 has been reported to associate with USP11, leading to regulation of polycomb repressive complex 1 (PRC1), but little is known about the mechanism of this interaction 36,37. Like USP7, USP11 appears to have multiple cancer-associated roles, that could either promote or suppress oncogenesis 38-42 and therefore a better understanding of the USP7-USP11 interaction

Molecular and Cellular Biology, 2009

p27 Kip1 is a cyclin-dependent kinase inhibitor that regulates the G 1 /S transition. Increased degradation of p27 Kip1 is associated with cellular transformation. Previous work demonstrated that the ubiquitin ligases KPC1/KPC2 and SCF Skp2 ubiquitinate p27 Kip1 in G 1 and early S, respectively. The regulation of these ligases remains unclear. We report here that the USP19 deubiquitinating enzyme interacts with and stabilizes KPC1, thereby modulating p27 Kip1 levels and cell proliferation. Cells depleted of USP19 by RNA interference exhibited an inhibition of cell proliferation, progressing more slowly from G 0 /G1 to S phase, and accumulated p27 Kip1 . This increase in p27 Kip1 was associated with normal levels of Skp2 but reduced levels of KPC1. The overexpression of KPC1 or the use of p27 ؊/؊ cells inhibited significantly the growth defect observed upon USP19 depletion. KPC1 was ubiquitinated in vivo and stabilized by proteasome inhibitors and by overexpression of USP19, and it also coimmunoprecipitated with USP19. Our results identify USP19 as the first deubiquitinating enzyme that regulates the stability of a cyclin-dependent kinase inhibitor and demonstrate that progression through G 1 to S phase is, like the metaphase-anaphase transition, controlled in a hierarchical, multilayered fashion.

Proceedings of the National Academy of Sciences

Overexpression of the deubiquitylase ubiquitin-specific peptidase 22 (USP22) is a marker of aggressive cancer phenotypes like metastasis, therapy resistance, and poor survival. Functionally, this overexpression of USP22 actively contributes to tumorigenesis, as USP22 depletion blocks cancer cell cycle progression in vitro, and inhibits tumor progression in animal models of lung, breast, bladder, ovarian, and liver cancer, among others. Current models suggest that USP22 mediates these biological effects via its role in epigenetic regulation as a subunit of the Spt-Ada-Gcn5-acetyltransferase (SAGA) transcriptional cofactor complex. Challenging the dogma, we report here a nontranscriptional role for USP22 via a direct effect on the core cell cycle machinery: that is, the deubiquitylation of the G1 cyclin D1 (CCND1). Deubiquitylation by USP22 protects CCND1 from proteasome-mediated degradation and occurs separately from the canonical phosphorylation/ubiquitylation mechanism previously s...

Mammalian Genome, 2010

USP32, on chromosomal band 17q23.1-17q23.2, is a highly conserved but uncharacterized gene that gave rise during evolution to a well-known hominoid-specific proto-oncogene, USP6. We investigated the expression profile of USP32 in human tissues and examined its functions to gain insight into this novel member of the well-conserved ubiquitination system. We detected ubiquitous USP32 expression across tissues and confirmed the predicted deubiquitination function owing to the presence of conserved peptidase signature aspargine, cysteine, histidine, and aspartic acid domains of ubiquitin-specific proteases. A Golgi localization of GFP-fused USP32 was detected by fluorescent protection assay and BODIPY-TR staining. In addition, stable silencing of USP32 caused a significant decrease in the proliferation and migration rate of cells. Based on these and the fact that USP32 maps to 17q23, which is commonly amplified in breast cancers, we analyzed USP32 expression in breast cancer cells. We detected high expression of USP32 in 50% (9 of 18) of breast cancer cell lines and 22% (9 of 41) of primary breast tumors compared to mammary epithelial cells. In summary, we report the preliminary characterization of this novel deubiquitinating enzyme on 17q23 and demonstrate its functional role in the ubiquitin system and its potential involvement in tumorigenesis.