title: Staurosporine-sensitive protein phosphorylation is required for postreplication DNA repair in human cells.
abstract: DNA repair is an important factor of stability of pro- and eukaryotic genomes which plays a central role in mutagenesis and carcinogenesis. Genetic control of nucleotide excision repair (NER) in mammalian cells is well studied, but little is known about molecular mechanisms of postreplication repair (PRR) which allows bypass of base lesions in template strands after DNA replication. In Saccharomyces cerevisiae PRR is controlled by the RAD61RAD18 pathway which involves POL30 gene encoding proliferating cell nuclear antigen (PCNA), and in human cells PCNA is known to be closely associated with the newly replicated chromatin where PRR probably takes place. In UV-irradiated human cells distinct PCNA foci may be detected in some cells which accumulate phosphorylated breast cancer susceptibility protein BRCA1 and another protein BARD1. Human PCNA is also known to be phosphorylated after UV-irradiation. In this study we found that the known inhibitor of protein kinases staurosporine supresses PRR in NER-deficient cells which is consistent with the view that BRCA1 and PCNA are required for PRR. We also have shown that the distinct PCNA foci in UV-irradiated NER-deficient cells are actually associated with the newly replicated chromatin. Since RAD18 protein is not essential for normal DNA replication and directly controls PRR in yeast, we analysed whether this protein as well as its human homologs (HR18A and HR18B) have common domains with BRCA1 and BARD1. It is found that HR18A has a subregion of homology to BARD1 and HR18A-to BRCA1. Taken together the results indicate that BRCA1 and BARD1 may be involved in PRR in human cells.
authors.affiliation: Institute of Cytology of the Russian Academy of Sciences, St. Petersburg.
authors.forename: M P
authors.initials: MP
authors.lastname: Svetlova
authors.forename: L V
authors.initials: LV
authors.lastname: Solovjeva
authors.forename: A A
authors.initials: AA
authors.lastname: Nikiforov
authors.forename: V A
authors.initials: VA
authors.lastname: Chagin
authors.forename: A R
authors.initials: AR
authors.lastname: Lehmann
authors.forename: N V
authors.initials: NV
authors.lastname: Tomilin
mesh_terms: D000595:Amino Acid Sequence; D019313:BRCA1 Protein / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D004260:DNA Repair; D004261:DNA Replication / Q000187:drug effects*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D008969:Molecular Sequence Data; D010766:Phosphorylation; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D019311:Staurosporine / Q000494:pharmacology*; D025521:Tumor Suppressor Proteins; D044767:Ubiquitin-Protein Ligases
chemical_list: D019313:BRCA1 Protein; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D018809:Proliferating Cell Nuclear Antigen; C063607:RAD18 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D025521:Tumor Suppressor Proteins; C102449:BARD1 protein, human; D044767:Ubiquitin-Protein Ligases; D019311:Staurosporine