title: P21Cip1/WAF1 downregulation is required for efficient PCNA ubiquitination after UV irradiation.
abstract: p21(Cip1/WAF1) is a known inhibitor of the short-gap filling activity of proliferating cell nuclear antigen (PCNA) during DNA repair. In agreement, p21 degradation after UV irradiation promotes PCNA-dependent repair. Recent reports have identified ubiquitination of PCNA as a relevant feature for PCNA-dependent DNA repair. Here, we show that PCNA ubiquitination in human cells is notably augmented after UV irradiation and other genotoxic treatments such as hydroxyurea, aphidicolin and methylmethane sulfonate. Intriguingly, those DNA damaging agents also promoted downregulation of p21. While ubiquitination of PCNA was not affected by deficient nucleotide excision repair (NER) and was observed in both proliferating and arrested cells, stable p21 expression caused a significant reduction in UV-induced ubiquitinated PCNA. Surprisingly, the negative regulation of PCNA ubiquitination by p21 does not depend on the direct interaction with PCNA but requires the cyclin dependent kinase binding domain of p21. Taken together, our data suggest that p21 downregulation plays a role in efficient PCNA ubiquitination after UV irradiation.
authors.affiliation: Fundación Instituto Leloir, CONICET, Buenos Aires, Argentina.
authors.forename: G
authors.initials: G
authors.lastname: Soria
authors.forename: O
authors.initials: O
authors.lastname: Podhajcer
authors.forename: C
authors.initials: C
authors.lastname: Prives
authors.forename: V
authors.initials: V
authors.lastname: Gottifredi
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D016590:Aphidicolin / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects / Q000528:radiation effects; D049109:Cell Proliferation / Q000187:drug effects / Q000528:radiation effects; D002478:Cells, Cultured / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D015179:Colorectal Neoplasms / Q000378:metabolism / Q000473:pathology; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism*; D004249:DNA Damage / Q000187:drug effects / Q000528:radiation effects; D004260:DNA Repair / Q000187:drug effects / Q000528:radiation effects; D015536:Down-Regulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D006801:Humans; D006918:Hydroxyurea / Q000494:pharmacology; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D009153:Mutagens / Q000494:pharmacology; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism*; D025801:Ubiquitin / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D000970:Antineoplastic Agents; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004791:Enzyme Inhibitors; D009153:Mutagens; D018809:Proliferating Cell Nuclear Antigen; D025801:Ubiquitin; D016590:Aphidicolin; D008741:Methyl Methanesulfonate; D006918:Hydroxyurea