title: Recruitment of RNA polymerase II cofactor PC4 to DNA damage sites.
abstract: The multifunctional nuclear protein positive cofactor 4 (PC4) is involved in various cellular processes including transcription, replication, and chromatin organization. Recently, PC4 has been identified as a suppressor of oxidative mutagenesis in Escherichia coli and Saccharomyces cerevisiae. To investigate a potential role of PC4 in mammalian DNA repair, we used a combination of live cell microscopy, microirradiation, and fluorescence recovery after photobleaching analysis. We found a clear accumulation of endogenous PC4 at DNA damage sites introduced by either chemical agents or laser microirradiation. Using fluorescent fusion proteins and specific mutants, we demonstrated that the rapid recruitment of PC4 to laser-induced DNA damage sites is independent of poly(ADP-ribosyl)ation and gammaH2AX but depends on its single strand binding capacity. Furthermore, PC4 showed a high turnover at DNA damages sites compared with the repair factors replication protein A and proliferating cell nuclear antigen. We propose that PC4 plays a role in the early response to DNA damage by recognizing single-stranded DNA and may thus initiate or facilitate the subsequent steps of DNA repair.
authors.affiliation: Department of Biology II, Ludwig Maximilians University Munich, 82152 Planegg-Martinsried, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Mortusewicz
authors.forename: Wera
authors.initials: W
authors.lastname: Roth
authors.forename: Na
authors.initials: N
authors.lastname: Li
authors.forename: M Cristina
authors.initials: MC
authors.lastname: Cardoso
authors.forename: Michael
authors.initials: M
authors.lastname: Meisterernst
authors.forename: Heinrich
authors.initials: H
authors.lastname: Leonhardt
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects / Q000201:enzymology* / Q000528:radiation effects; D004249:DNA Damage; D004260:DNA Repair; D004277:DNA, Single-Stranded / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D036681:Fluorescence Recovery After Photobleaching; D006367:HeLa Cells; D006657:Histones / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D051379:Mice; D018345:Mice, Knockout; D008856:Microscopy, Fluorescence; D009154:Mutation; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism*; D012319:RNA Polymerase II / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D051716:Replication Protein A / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
chemical_list: D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D006657:Histones; D018809:Proliferating Cell Nuclear Antigen; D011993:Recombinant Fusion Proteins; D051716:Replication Protein A; C509201:SUB1 protein, human; D014157:Transcription Factors; C475961:gamma-H2AX protein, mouse; C499321:Parp1 protein, mouse; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D012319:RNA Polymerase II