title: Involvement of DNA polymerase beta in DNA replication and mutagenic consequences.
abstract: Overexpression in mammalian cells of the error-prone DNA polymerase beta (Pol beta) has been found to increase the spontaneous mutagenesis. Here, we investigated a possible mechanism used by Pol beta to be a genetic instability enhancer: its interference in replicative DNA synthesis, which is normally catalysed by the DNA polymerases alpha, delta and epsilon. By taking advantage of the ability to incorporate efficiently into DNA the chain terminator ddCTP as well as the oxidised nucleotide 8-oxo-dGTP, we show here that purified Pol beta can compete with the replicative DNA polymerases during replication in vitro of duplex DNA when added to human cell extracts. We found that involvement of Pol beta lowers replication fidelity and results in a modified error-specificity. Furthermore, we demonstrated that involvement of Pol beta occurred during synthesis of the lagging strand. These in vitro data provide one possible explanation of how overexpression of the enzyme could perturb the genetic instability in mammalian cells. We discuss these findings within the scope of the up-regulation of Pol beta in many cancer cells.
authors.affiliation: The Institut de Pharmacologie et Biologie Structurale, UMR CNRS 5089, Toulouse cédex 4, 31077, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Servant
authors.forename: Anne
authors.initials: A
authors.lastname: Bieth
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hayakawa
authors.forename: Christophe
authors.initials: C
authors.lastname: Cazaux
authors.forename: Jean-Sébastien
authors.initials: JS
authors.lastname: Hoffmann
mesh_terms: D000818:Animals; D000957:Antigens, Viral, Tumor / Q000378:metabolism; D001483:Base Sequence; D002138:Calibration; D002417:Cattle; D002457:Cell Extracts; D002474:Cell-Free System; D019951:DNA Polymerase beta / Q000378:metabolism*; D004261:DNA Replication; D004277:DNA, Single-Stranded / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D004279:DNA, Viral / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D003845:Deoxycytosine Nucleotides / Q000378:metabolism; D003848:Deoxyguanine Nucleotides / Q000378:metabolism; D054306:Dideoxynucleotides; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D016296:Mutagenesis / Q000235:genetics*; D013539:Simian virus 40 / Q000235:genetics; D013379:Substrate Specificity; D013698:Templates, Genetic
chemical_list: D000957:Antigens, Viral, Tumor; D002457:Cell Extracts; D004277:DNA, Single-Stranded; D004279:DNA, Viral; D003845:Deoxycytosine Nucleotides; D003848:Deoxyguanine Nucleotides; D054306:Dideoxynucleotides; C078206:8-oxodeoxyguanosine triphosphate; C037406:2',3'-dideoxycytidine 5'-triphosphate; D019951:DNA Polymerase beta