title: USP7 modulates UV-induced PCNA monoubiquitination by regulating DNA polymerase eta stability.
abstract: DNA polymerase eta (Polη) has unique and pivotal functions in several DNA damage-tolerance pathways. Steady-state level of this short-lived protein is tightly controlled by multiple mechanisms including proteolysis. Here, we have identified the deubiquitinating enzyme (DUB), ubiquitin-specific protease 7 (USP7), as a novel regulator of Polη stability. USP7 regulates Polη stability through both indirect and direct mechanisms. Knockout of USP7 increased the steady-state level of Polη and slowed down the turnover of both Polη and p53 proteins through destabilizing their E3 ligase murine double minute 2 (Mdm2). Also, USP7 physically binds Polη in vitro and in vivo. Overexpression of wild-type USP7 but not its catalytically-defective mutants deubiquitinates Polη and increases its cellular steady-state level. Thus, USP7 directly serves as a specific DUB for Polη. Furthermore, ectopic expression of USP7 promoted the UV-induced proliferating cell nuclear antigen (PCNA) monoubiquitination in Polη-proficient but not in Polη-deficient XPV (Xeroderma pigmentosum variant) cells, suggesting that USP7 facilitates UV-induced PCNA monoubiquitination by stabilizing Polη. Taken together, our findings reveal a modulatory role of USP7 in PCNA ubiquitination-mediated stress-tolerance pathways by fine-tuning Polη turnover.
authors.affiliation: Department of Radiology, The Ohio State University, Columbus, OH, USA.
authors.forename: J
authors.initials: J
authors.lastname: Qian
authors.affiliation: Department of Radiology, The Ohio State University, Columbus, OH, USA.
authors.forename: K
authors.initials: K
authors.lastname: Pentz
authors.affiliation: Department of Radiology, The Ohio State University, Columbus, OH, USA.
authors.forename: Q
authors.initials: Q
authors.lastname: Zhu
authors.affiliation: Department of Radiology, The Ohio State University, Columbus, OH, USA.
authors.forename: Q
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Radiology, The Ohio State University, Columbus, OH, USA.
authors.forename: J
authors.initials: J
authors.lastname: He
authors.affiliation: Department of Radiology, The Ohio State University, Columbus, OH, USA.
authors.forename: A K
authors.initials: AK
authors.lastname: Srivastava
authors.affiliation: Department of Radiology, The Ohio State University, Columbus, OH, USA.|Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, OH, USA.|James Cancer Hospital and Solove Research Institute, The Ohio State University, Columbus, OH, USA.
authors.forename: A A
authors.initials: AA
authors.lastname: Wani
mesh_terms: D000818:Animals; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology; D004249:DNA Damage / Q000235:genetics / Q000528:radiation effects; D004261:DNA Replication / Q000235:genetics / Q000528:radiation effects; D004259:DNA-Directed DNA Polymerase / Q000235:genetics* / Q000378:metabolism; D004795:Enzyme Stability / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic / Q000528:radiation effects; D055786:Gene Knockout Techniques; D045325:HCT116 Cells; D006801:Humans; D051379:Mice; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism*; D051736:Proto-Oncogene Proteins c-mdm2 / Q000235:genetics / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D043222:Ubiquitin Thiolesterase / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D000076084:Ubiquitin-Specific Peptidase 7; D054875:Ubiquitination / Q000235:genetics / Q000528:radiation effects; D014466:Ultraviolet Rays; D000099270:Y-Family DNA Polymerases
chemical_list: D004259:DNA-Directed DNA Polymerase; D018809:Proliferating Cell Nuclear Antigen; D051736:Proto-Oncogene Proteins c-mdm2; D016159:Tumor Suppressor Protein p53; D043222:Ubiquitin Thiolesterase; D000076084:Ubiquitin-Specific Peptidase 7; C495901:TP53 protein, human; C497206:MDM2 protein, human; C112338:Rad30 protein; D000099270:Y-Family DNA Polymerases; C464569:USP7 protein, human