USP2 is an SKP2 deubiquitylase that stabilizes both SKP2 and its substrates
Fengwu Zhang, Yongchao Zhao, Yi Sun
Abstract
The stability of a protein is regulated by a balance between its ubiquitylation and deubiquitylation. S-phase kinase-associated protein 2 (SKP2) is an oncogenic F-box protein that recognizes tumor suppressor substrates for targeted ubiquitylation by the E3 ligase SKP1-Cullin1-F-box and degradation by proteasome. SKP2 is itself ubiquitylated by the E3 ligases APC/CCDH1 and SCFFBXW2, and deubiquitylated by deubiquitylases (DUBs) USP10 and USP13. Given the biological significance of SKP2, it is likely that the other E3s or DUBs may also regulate its stability. Here, we report the identification and characterization of USP2 as a new DUB. We first screened a panel of DUBs and found that both USP2 and USP21 bound to endogenous SKP2, but only USP2 deubiquitylated and stabilized SKP2 protein. USP2 inactivation via siRNA knockdown or small-molecule inhibitor treatment remarkably shortened SKP2 protein half-life by enhancing its ubiquitylation and subsequent degradation. Unexpectedly, USP2-stabilized SKP2 did not destabilize its substrates p21 and p27. Mechanistically, USP2 bound to SKP2 via the leucine-rich repeat substrate-binding domain on SKP2 to disrupt the SKP2-substrate binding, leading to stabilization of both SKP2 and these substrates. Biologically, growth suppression induced by USP2 knockdown or USP2 inhibitor is partially mediated via modulation of SKP2 and its substrates. Our study revealed a new mechanism of the cross-talk among the E3–DUB substrates and its potential implication in targeting the USP2–SKP2 axis for cancer therapy. The stability of a protein is regulated by a balance between its ubiquitylation and deubiquitylation. S-phase kinase-associated protein 2 (SKP2) is an oncogenic F-box protein that recognizes tumor suppressor substrates for targeted ubiquitylation by the E3 ligase SKP1-Cullin1-F-box and degradation by proteasome. SKP2 is itself ubiquitylated by the E3 ligases APC/CCDH1 and SCFFBXW2, and deubiquitylated by deubiquitylases (DUBs) USP10 and USP13. Given the biological significance of SKP2, it is likely that the other E3s or DUBs may also regulate its stability. Here, we report the identification and characterization of USP2 as a new DUB. We first screened a panel of DUBs and found that both USP2 and USP21 bound to endogenous SKP2, but only USP2 deubiquitylated and stabilized SKP2 protein. USP2 inactivation via siRNA knockdown or small-molecule inhibitor treatment remarkably shortened SKP2 protein half-life by enhancing its ubiquitylation and subsequent degradation. Unexpectedly, USP2-stabilized SKP2 did not destabilize its substrates p21 and p27. Mechanistically, USP2 bound to SKP2 via the leucine-rich repeat substrate-binding domain on SKP2 to disrupt the SKP2-substrate binding, leading to stabilization of both SKP2 and these substrates. Biologically, growth suppression induced by USP2 knockdown or USP2 inhibitor is partially mediated via modulation of SKP2 and its substrates. Our study revealed a new mechanism of the cross-talk among the E3–DUB substrates and its potential implication in targeting the USP2–SKP2 axis for cancer therapy. The stability of a protein is precisely regulated by a fine balance between ubiquitylation, a process that destabilizes it, and deubiquitylation, a process that stabilizes it (1Weissman A.M. Shabek N. Ciechanover A. The predator becomes the prey: Regulating the ubiquitin system by ubiquitylation and degradation.Nat. Rev. Mol. Cell Biol. 2011; 12: 605-620Crossref PubMed Scopus (228) Google Scholar). Ubiquitylation is catalyzed by a three-enzyme cascade, consisting of E1 ubiquitin-activating enzyme, E2 ubiquitin-conjugating enzyme, and E3 ubiquitin ligases, leading to a covalent attachment of ubiquitin molecule to a substrate protein, which is recognized by the proteasome system for degradation (2Bedford L. Lowe J. Dick L.R. Mayer R.J. Brownell J.E. Ubiquitin-like protein conjugation and the ubiquitin-proteasome system as drug targets.Nat. Rev. Drug Discov. 2011; 10: 29-46Crossref PubMed Scopus (392) Google Scholar). Deubiquitylation is a reversed process, catalyzed by deubiquitylase, which binds to ubiquitylated substrates and removes/cleaves the ubiquitin from proteins to disassemble polyubiquitylation chains from substrates before proteasomal degradation (3Cheng J. Guo J. North B.J. Wang B. Cui C.P. Li H. Tao K. Zhang L. Wei W. Functional analysis of deubiquitylating enzymes in tumorigenesis and development.Biochim. Biophys. Acta Rev. Cancer. 2019; 1872: 188312Crossref PubMed Scopus (29) Google Scholar). Through the highly regulated processes of ubiquitylation and deubiquitylation, the ubiquitin–proteasome system precisely controls the fate of substrate protein (4Collins G.A. Goldberg A.L. The logic of the 26S proteasome.Cell. 2017; 169: 792-806Abstract Full Text Full Text PDF PubMed Scopus (413) Google Scholar). The E3 ubiquitin ligases can be categorized into four classes: N-end rule; homology to E6AP C terminus; really interesting new gene (RING); and anaphase-promoting complex/cyclosome (APC/C) (5Zhao Y. Sun Y. Cullin-RING Ligases as attractive anti-cancer targets.Curr. Pharm. Des. 2013; 19: 3215-3225Crossref PubMed Scopus (172) Google Scholar, 6Hershko A. Ciechanover A. The ubiquitin system.Annu. Rev. Biochem. 1998; 67: 425-479Crossref PubMed Scopus (6728) Google Scholar). Among 600 different types of E3 ligases, SKP1-Cullin1-F-box (SCF) under the RING class category is the largest family, consisting of four components: scaffold cullin, adaptor SKP1, RING RBX/ROC, and substrate receptor, F-box proteins (7Jia L. Sun Y. SCF E3 ubiquitin ligases as anticancer targets.Curr. Cancer Drug Targets. 2011; 11: 347-356Crossref PubMed Scopus (106) Google Scholar, 8Petroski M.D. Deshaies R.J. Function and regulation of cullin-RING ubiquitin ligases.Nat. Rev. Mol. Cell. Biol. 2005; 6: 9-20Crossref PubMed Scopus (1629) Google Scholar). In mammalian cells, there are 69 different F-box proteins and among them, S-phase kinase-associated protein 2 (SKP2, also known as F-box and leucine-rich repeat protein 1) is one of the best-studied proteins (9Frescas D. Pagano M. Deregulated proteolysis by the F-box proteins SKP2 and beta-TrCP: Tipping the scales of cancer.Nat. Rev. Cancer. 2008; 8: 438-449Crossref PubMed Scopus (709) Google Scholar, 10Jin J. Cardozo T. Lovering R.C. Elledge S.J. Pagano M. Harper J.W. Systematic analysis and nomenclature of mammalian F-box proteins.Genes Dev. 2004; 18: 2573-2580Crossref PubMed Scopus (525) Google Scholar). It has been well documented that SKP2 is overexpressed in numerous human cancers and SKP2 overexpression is positively associated with poor survival of patients with cancer (9Frescas D. Pagano M. Deregulated proteolysis by the F-box proteins SKP2 and beta-TrCP: Tipping the scales of cancer.Nat. Rev. Cancer. 2008; 8: 438-449Crossref PubMed Scopus (709) Google Scholar). Mechanistically, SKP2 acts as an oncogene by recognizing and promoting the ubiquitylation and degradation of tumor suppressor proteins, such as p21 (11Bornstein G. Bloom J. Sitry-Shevah D. Nakayama K. Pagano M. Hershko A. Role of the SCFSkp2 ubiquitin ligase in the degradation of p21Cip1 in S phase.J. Biol. Chem. 2003; 278: 25752-25757Abstract Full Text Full Text PDF PubMed Scopus (386) Google Scholar, 12Yu Z.K. Gervais J.L. Zhang H. Human CUL-1 associates with the SKP1/SKP2 complex and regulates p21(CIP1/WAF1) and cyclin D proteins.Proc. Natl. Acad. Sci. U. S. A. 1998; 95: 11324-11329Crossref PubMed Scopus (348) Google Scholar), p27 (13Kossatz U. Dietrich N. Zender L. Buer J. Manns M.P. Malek N.P. Skp2-dependent degradation of p27kip1 is essential for cell cycle progression.Genes Dev. 2004; 18: 2602-2607Crossref PubMed Scopus (151) Google Scholar, 14Nakayama K. Nagahama H. Minamishima Y.A. Miyake S. Ishida N. Hatakeyama S. Kitagawa M. Iemura S. Natsume T. Nakayama K.I. Skp2-mediated degradation of p27 regulates progression into mitosis.Dev. Cell. 2004; 6: 661-672Abstract Full Text Full Text PDF PubMed Scopus (309) Google Scholar, 15Spruck C. Strohmaier H. Watson M. Smith A.P. Ryan A. Krek T.W. Reed S.I. A CDK-independent function of mammalian Cks1: Targeting of SCF(Skp2) to the CDK inhibitor p27Kip1.Mol. Cell. 2001; 7: 639-650Abstract Full Text Full Text PDF PubMed Scopus (327) Google Scholar), p57 (16Kamura T. Hara T. Kotoshiba S. Yada M. Ishida N. Imaki H. Hatakeyama S. Nakayama K. Nakayama K.I. Degradation of p57Kip2 mediated by SCFSkp2-dependent ubiquitylation.Proc. Natl. Acad. Sci. U. S. A. 2003; 100: 10231-10236Crossref PubMed Scopus (248) Google Scholar), and FOXO1 (17Huang H. Regan K.M. Wang F. Wang D. Smith D.I. van Deursen J.M. Tindall D.J. Skp2 inhibits FOXO1 in tumor suppression through ubiquitin-mediated degradation.Proc. Natl. Acad. Sci. U. S. A. 2005; 102: 1649-1654Crossref PubMed Scopus (422) Google Scholar). By doing so, SKP2 accelerates the S phase entry to promote cell proliferation, migration, and invasion. Thus, SKP2 has been well validated as a promising cancer target for anticancer drug discovery (18Cai Z. Moten A. Peng D. Hsu C.C. Pan B.S. Manne R. Li H.Y. Lin H.K. The Skp2 pathway: A critical target for cancer therapy.Semin. Cancer Biol. 2020; 67: 16-33Crossref PubMed Scopus (40) Google Scholar). Deubiquitylases (DUBs) are categorized into seven subfamilies, including ubiquitin-specific proteases (USPs), ubiquitin carboxyl-terminal hydrolases, ovarian tumor proteases, Machado–Josephin domain–containing proteases, motif-interacting with ubiquitin-containing novel DUB family (MINDYs), ZUP1, and JAB1/MPN/MOV34 metalloenzymes (19Komander D. Clague M.J. Urbe S. Breaking the chains: Structure and function of the deubiquitinases.Nat. Rev. Mol. Cell Biol. 2009; 10: 550-563Crossref PubMed Scopus (1388) Google Scholar). USPs are the most abundant DUBs among all subfamilies (20Reyes-Turcu F.E. Ventii K.H. Wilkinson K.D. Regulation and cellular roles of ubiquitin-specific deubiquitinating enzymes.Annu. Rev. Biochem. 2009; 78: 363-397Crossref PubMed Scopus (1029) Google Scholar). USP2 was first identified as an inducible USP enzyme in rat testes (21Lin H. Keriel A. Morales C.R. Bedard N. Zhao Q. Hingamp P. Lefrancois S. Combaret L. Wing S.S. Divergent N-terminal sequences target an inducible testis deubiquitinating enzyme to distinct subcellular structures.Mol. Cell Biol. 2000; 20: 6568-6578Crossref PubMed Scopus (58) Google Scholar). USP2 was characterized as a bona fide oncogene via stabilizing many oncoproteins, including TGF-b serine/threonine kinase Y. Wang Wang Q. Y. Li K. Zhang M. Zhang Q. J. Wang H.Y. P. Y. Zhang N. Li W. Y. W. by Full Text Full Text PDF PubMed Scopus Google Scholar), 2 A. N. The deubiquitinating enzyme regulates the by targeting J. PubMed Scopus Google Scholar), N. A. is a substrate for the deubiquitinating enzyme PubMed Scopus Google Scholar), and D. S. A. T. M. D. J. S. M. The regulates the stability of in Cell. 2004; Full Text Full Text PDF PubMed Scopus Google Scholar). USP2 was overexpressed in human cancers and is for tumorigenesis (3Cheng J. Guo J. North B.J. Wang B. Cui C.P. Li H. Tao K. Zhang L. Wei W. Functional analysis of deubiquitylating enzymes in tumorigenesis and development.Biochim. Biophys. Acta Rev. Cancer. 2019; 1872: 188312Crossref PubMed Scopus (29) Google Scholar). that SKP2 is to ubiquitylation by APC/CCDH1 E3 ligase for proteasome degradation W. Y. Zhang Degradation of the SCF Skp2 in phase by the anaphase-promoting 2004; PubMed Scopus Google Scholar), leading to of its substrate p27 to that the to S phase progression is are Our study that SKP2 is also to ubiquitylation by to precisely of cell cycle progression in a of APC/CCDH1 E3 ligase J. W. F. G. Li H. Zhao Y. P. Li H. M. Sun Y. The axis regulates cancer cell growth with as a 2017; 8: PubMed Scopus Google Scholar). the other USP10 Y. N. Guo Z. Li Y. L. R. D. H. J. USP10 the axis via stabilizing SKP2 in Discov. 2019; PubMed Scopus Google and M. protein the to cell cycle Natl. Acad. Sci. U. S. A. 2011; PubMed Scopus Google to promote SKP2 deubiquitylation. USP10 stabilized SKP2 and via polyubiquitylation Y. N. Guo Z. Li Y. L. R. D. H. J. USP10 the axis via stabilizing SKP2 in Discov. 2019; PubMed Scopus Google Scholar), the axis to regulate the M. protein the to cell cycle Natl. Acad. Sci. U. S. A. 2011; PubMed Scopus Google Scholar). In we a panel of DUBs for potential of endogenous SKP2 by a and found that both USP2 and USP21 to SKP2, but only USP2 stabilized Unexpectedly, stabilized SKP2 did not destabilize its substrates by promoting ubiquitylation and degradation. is to USP2 to SKP2 via the leucine-rich repeat domain on SKP2, the domain that SKP2 substrate The USP2–SKP2 the SKP2 substrate Thus, USP2 stabilizes both SKP2 and SKP2 substrates. Biologically, growth suppression induced by USP2 knockdown or USP2 inhibitor to be partially mediated via SKP2 and its substrates. Our study a new mechanism of the cross-talk among the and substrates. DUBs with potential to SKP2, we the to which DUB to endogenous A panel of DUBs and was into cells, by and for Among the USP2 and USP21 bound to SKP2 of but not protein half-life of SKP2 knockdown of but not endogenous of SKP2 in cancer cell but not is likely an SKP2 We that of but not of its of endogenous SKP2 in a and endogenous USP2 and SKP2 bound to other under a in a these that USP2 and stabilizes We the that USP2 may SKP2 The USP2 knockdown the USP2 but on SKP2 that USP2 regulates SKP2 not the We found that USP2 knockdown SKP2 protein which is by proteasome that the regulation the USP2 knockdown shortened the protein half-life of SKP2 and the polyubiquitylation of SKP2 USP2 the ubiquitin chains from SKP2 in a of its a to the protein half-life of SKP2 USP2 is a bona fide SKP2 that regulated SKP2 degradation. a small-molecule inhibitor of was to the biological of USP2 R. M. K. L. C. L. M.D. C. P. H. D. molecule of the ubiquitin-specific USP2 accelerates cyclin degradation and to cell cycle in cancer and cell Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). We as a to the of USP2 on in cancer cell the of SKP2, as well as and known substrates of USP2 A. N. The deubiquitinating enzyme regulates the by targeting J. PubMed Scopus Google Scholar, Y. L.R. A. Y. J. regulates the stability of Biol. Chem. 2011; Full Text Full Text PDF PubMed Scopus Google Scholar), as the in a and which can be by shortened the protein half-life of SKP2 and SKP2 polyubiquitylation we of and E3 ubiquitin ligases known to SKP2 W. Y. Zhang Degradation of the SCF Skp2 in phase by the anaphase-promoting 2004; PubMed Scopus Google Scholar, J. W. F. G. Li H. Zhao Y. P. Li H. M. Sun Y. The axis regulates cancer cell growth with as a 2017; 8: PubMed Scopus Google Scholar), to SKP2 We or or in and found that or knockdown SKP2 polyubiquitylation induced by The that SKP2 polyubiquitylation is by and and deubiquitylated by which is by Thus, SKP2 polyubiquitylation is in a of both and we validated that SKP2 is a substrate of USP2 both and We the of USP2 on SKP2 substrates with that USP2 the of SKP2 its SKP2 stabilization USP2 the of both SKP2 and SKP2 p21 (11Bornstein G. Bloom J. Sitry-Shevah D. Nakayama K. Pagano M. Hershko A. Role of the SCFSkp2 ubiquitin ligase in the degradation of p21Cip1 in S phase.J. Biol. Chem. 2003; 278: 25752-25757Abstract Full Text Full Text PDF PubMed Scopus (386) Google Scholar, 12Yu Z.K. Gervais J.L. Zhang H. Human CUL-1 associates with the SKP1/SKP2 complex and regulates p21(CIP1/WAF1) and cyclin D proteins.Proc. Natl. Acad. Sci. U. S. A. 1998; 95: 11324-11329Crossref PubMed Scopus (348) Google and p27 (13Kossatz U. Dietrich N. Zender L. Buer J. Manns M.P. Malek N.P. Skp2-dependent degradation of p27kip1 is essential for cell cycle progression.Genes Dev. 2004; 18: 2602-2607Crossref PubMed Scopus (151) Google Scholar, 14Nakayama K. Nagahama H. Minamishima Y.A. Miyake S. Ishida N. Hatakeyama S. Kitagawa M. Iemura S. Natsume T. Nakayama K.I. Skp2-mediated degradation of p27 regulates progression into mitosis.Dev. Cell. 2004; 6: 661-672Abstract Full Text Full Text PDF PubMed Scopus (309) Google Scholar, 15Spruck C. Strohmaier H. Watson M. Smith A.P. Ryan A. Krek T.W. Reed S.I. A CDK-independent function of mammalian Cks1: Targeting of SCF(Skp2) to the CDK inhibitor p27Kip1.Mol. Cell. 2001; 7: 639-650Abstract Full Text Full Text PDF PubMed Scopus (327) Google in and USP2 overexpression also the of SKP2 cyclin Z.K. Gervais J.L. Zhang H. Human CUL-1 associates with the SKP1/SKP2 complex and regulates p21(CIP1/WAF1) and cyclin D proteins.Proc. Natl. Acad. Sci. U. S. A. 1998; 95: 11324-11329Crossref PubMed Scopus (348) Google and cyclin E2 K. Nagahama H. Minamishima Y.A. M. Kitagawa K. M. R. T. Ishida N. Kitagawa M. Nakayama K. Hatakeyama S. of Skp2 in of cyclin and and J. 2000; 19: PubMed Scopus Google in with the but not in with USP2 knockdown the protein of these SKP2 including cyclin H. R. K. D. and are essential of the cyclin S phase Full Text PDF PubMed Scopus Google Scholar), cyclin and cyclin E2 the of p21 and p27 USP2 knockdown shortened the protein half-life of SKP2 as well as its p21 and p27 Thus, USP2 stabilized both SKP2 and SKP2 substrates. We the mechanism of We first that USP2 did not to SKP2 the that USP2 stabilizes SKP2 substrates by deubiquitylating We found that SKP2 knockdown the of its as and SKP2 substrates by USP2 knockdown Thus, is a E3 ligase in these cancer cells, and USP2 regulation of SKP2 substrate stability is in a on We the domain on SKP2 and found that it is mediated by the domain–containing C but not the F-box domain–containing of SKP2 Given that the domain is known to SKP2 substrate Z. Elledge S.J. Harper J.W. Pagano M. N.P. into SCF ubiquitin ligases from the of the 2000; PubMed Scopus Google Scholar, N. L. Wang P. C. Elledge S.J. Pagano M. R.C. J.W. Harper J.W. N.P. Structure of the SCF ubiquitin ligase PubMed Scopus Google Scholar), we that USP2 may with SKP2 substrates for SKP2 USP2 the SKP2 with its cyclin and cyclin E2 USP2 knockdown the SKP2 with its p21 and cyclin It is well known that the SCF E3 substrate of the the is also We cell with and found a of the SKP2 substrate binding, as but the Thus, the to be It has been that USP2 K.H. J.M. Iemura S. Natsume T. S. K. of cell by of ubiquitin E3 ligase and USP2 deubiquitinating 2011; 18: PubMed Scopus Google with the substrates but did not regulate substrate stability. an in ubiquitylation in both and cells, we found that p21 polyubiquitylation by SKP2 can be by or that USP2 regulation of SKP2 substrate stability is on its DUB we endogenous by or to the on protein of SKP2 and SKP2 substrates. We found that both and the of SKP2 only SKP2 protein these that USP2 has on SKP2 it the SKP2 with its leading to substrate we the biological significance of the USP2–SKP2 USP2 knockdown via growth of both and cancer cells, which can be by of SKP2 Given that USP2 knockdown the of both SKP2 and SKP2 p21 and p27 growth to be mediated by other substrates of USP2 in a of we did not SKP2 under in which the of SKP2 substrates p21 and p27 by SKP2 overexpression in with USP2 knockdown of SKP2 p21 and p27 that under SKP2, was promoting degradation of its p21 and p27 to cell leading to the Thus, SKP2 to a in in USP2 function on cell growth suppression was also USP2 inactivation by which was also partially by SKP2 but to a We that USP2 molecule is to disrupt the USP2–SKP2 binding, leading to SKP2 to its substrates. only in the of p21 and p27 was SKP2 overexpression in the that USP2 with SKP2 for its substrate an in protein through subcellular and of a protein T. in Mol. Biol. PubMed Scopus Google Scholar). The axis is one of the that regulates protein stability. We that USP2 is a new of SKP2 E3 which stabilized both SKP2 and SKP2 substrates. USP10 and to deubiquitylating In cells, USP10 deubiquitylated SKP2 to The SKP2 polyubiquitylation via the leading to and of to a kinase which is by USP10 Y. N. Guo Z. Li Y. L. R. D. H. J. USP10 the axis via stabilizing SKP2 in Discov. 2019; PubMed Scopus Google Scholar). In cells, the protein was as a scaffold protein for to SKP2 by USP13. to the leading to SKP2 and p27 p27 phase to the of proteins M. protein the to cell cycle Natl. Acad. Sci. U. S. A. 2011; PubMed Scopus Google Scholar). in both the did not the of USP10 or on The DUBs in many cellular and as novel anticancer P. Wang S. as a cancer PubMed Scopus Google Scholar). USP2 is overexpressed in human which is positively with tumor (3Cheng J. Guo J. North B.J. Wang B. Cui C.P. Li H. Tao K. Zhang L. Wei W. Functional analysis of deubiquitylating enzymes in tumorigenesis and development.Biochim. Biophys. Acta Rev. Cancer. 2019; 1872: 188312Crossref PubMed Scopus (29) Google Scholar, J.M. D. J.M. C. in and PubMed Scopus Google Scholar). USP2 acts as an oncogenic protein by deubiquitylating and stabilizing oncogenic USP2 stabilized to promote degradation to A. N. The deubiquitinating enzyme regulates the by targeting J. PubMed Scopus Google to regulate cancer cell survival D. S. A. T. M. D. J. S. M. The regulates the stability of in Cell. 2004; Full Text Full Text PDF PubMed Scopus Google to cell cycle Y. L.R. A. Y. J. regulates the stability of Biol. Chem. 2011; Full Text Full Text PDF PubMed Scopus Google and TGF-b serine/threonine kinase to promote Y. Wang Wang Q. Y. Li K. Zhang M. Zhang Q. J. Wang H.Y. P. Y. Zhang N. Li W. Y. W. by Full Text Full Text PDF PubMed Scopus Google Scholar). Thus, USP2 to be an attractive anticancer and small-molecule of USP2 to growth and of cancer Y. Wang Wang Q. Y. Li K. Zhang M. Zhang Q. J. Wang H.Y. P. Y. Zhang N. Li W. Y. W. by Full Text Full Text PDF PubMed Scopus Google Scholar, J. S. D. Guo H. of USP2 cancer and to 2019; 10: PubMed Scopus Google Scholar). The in is not and deubiquitylated both and a of of deubiquitylated through Li M. M. Y. W. The complex is in stabilization by PubMed Scopus Google Scholar). In regulated the stability of both protein and substrates in a of stabilized to substrate its destabilizes to substrate the other overexpression stabilized or its substrates also in a overexpression a or stabilized or substrates to via and to and deubiquitylating C. J. W. L. A. A. M. N. regulation of function and oncogenic by Full Text Full Text PDF PubMed Scopus Google Scholar). In we that USP2 is a new bona fide of SKP2, which is by the of SKP2 with USP2 under the of endogenous SKP2 are regulated by USP2 with USP2 knockdown to and USP2 overexpression to USP2 stabilized SKP2 by SKP2 polyubiquitylation chains to SKP2 of USP2 SKP2 and USP2 on Thus, stabilization of oncogenic SKP2 be mechanism by which USP2 acts as an oncogenic protein. is of USP2 stabilization of and SKP2 stabilization did not degradation of SKP2 USP2 SKP2 with its substrates via the domain of SKP2 substrate The that of USP2 of to SKP2, on SKP2 but did the of SKP2 a of USP2 SKP2 substrates. we the that ubiquitylated SKP2 E3 ubiquitin ligase to its substrates. is biological of USP2 stabilization of is a to the that USP2 has substrates in to SKP2 and USP2 positively regulates both SKP2 and SKP2 which or inhibits cell we found that USP2 via knockdown or small-molecule inhibitor growth of cancer cells, which to be of SKP2 the of both SKP2 and SKP2 p21 and the that growth suppression induced by USP2 inactivation can be in by SKP2 a by In we an mechanism among the of a an E3 and its which Our study the that USP2 has a in stabilizing both SKP2 and SKP2 substrate through to the domain on SKP2 is of USP2 binding, it the degradation of p21 and and SKP2 binds to p21 and p27 are and stabilized cell in study from the and in the with and and in with and and a from and F. J. Li H. M. Sun Y. and of cancer via promoting ubiquitylation and degradation.Nat. 2019; 10: PubMed Scopus Google Scholar). The was by the The for as and SKP2 into The for as and for N-terminal SKP2 and and for The sequences of siRNA as and into the The targeting for USP2 was as The inhibitor of was from was from and Cell from with or siRNA to the by in and for with and in the and The of to the protein was the protein in the with and the with or or SKP2 by in a The with the for four and to as SKP2 p21 p27 cyclin cyclin cyclin E2 SKP2 USP2 and in the and was and to The by and to The sequences as and for and for and for and for and for p27. or with the siRNA for and with for before the in the the with for as Y. Sun Y. an is a substrate of E3 ubiquitin ligase and regulates survival and Cell. 2011; Full Text Full Text PDF PubMed Scopus Google Scholar). was with of A and with and with for in proteins from with the for and to with the siRNA for into a in and cell was by was in and to and the was for and the for well was on a The was between the by with the from biological are the The that of with the of F. Z. Y. Z. and Y. S. Y. Z. and Y. S. was by the of to Y. S. and Y. the of to Y. S. and and to Y.