title: Polkappa protects mammalian cells against the lethal and mutagenic effects of benzo[a]pyrene.
abstract: Several low-fidelity DNA polymerases have recently been discovered that are able to bypass DNA lesions during DNA synthesis in vitro. The efficiency and accuracy of lesion bypass is, however, both polymerase and lesion specific. For example, in vitro studies revealed that human DNA polymerase kappa (Polkappa) is unable to insert a base opposite a cis-syn thymine-thymine dimer or cisplatin adduct, yet can bypass some DNA lesions such as abasic site and acetylaminofluorene-adducted guanine in an error-prone manner. More importantly, Polkappa is able to bypass benzo[a]pyrene (B[a]P)-adducted guanine accurately and efficiently. To investigate the biological function of Polkappa, we have generated mouse embryonic stem (ES) cells deficient in the Polk gene encoding the enzyme. Polk-deficient ES cells grow normally and their sensitivities to UV and x-ray radiation are only slightly affected. In contrast, the mutant cells are highly sensitive to both killing and mutagenesis induced by B[a]P. Furthermore, the spectrum of mutations recovered in the Polk-deficient cells is different from that in the wild-type cells. Thus, our results indicate that Polkappa plays an important role in suppressing mutations at DNA lesions generated by B[a]P.
authors.affiliation: Laboratories of Gene Information Analysis and Signal Transduction, Institute for Virus Research, Kyoto University, Shogoin Kawara-cho 53, Sakyo-ku, Japan.
authors.forename: Tomoo
authors.initials: T
authors.lastname: Ogi
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Shinkai
authors.forename: Kiyoji
authors.initials: K
authors.lastname: Tanaka
authors.forename: Haruo
authors.initials: H
authors.lastname: Ohmori
mesh_terms: D000818:Animals; D001564:Benzo(a)pyrene / Q000633:toxicity*; D002478:Cells, Cultured / Q000187:drug effects / Q000201:enzymology / Q000528:radiation effects; D003114:Colony-Forming Units Assay; D004247:DNA / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D018736:DNA Adducts; D004249:DNA Damage; D004260:DNA Repair / Q000235:genetics; D004259:DNA-Directed DNA Polymerase / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D005091:Exons / Q000235:genetics; D005260:Female; D018390:Gene Targeting; D005796:Genes; D005813:Genes, Synthetic; D007438:Introns / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D016296:Mutagenesis; D013234:Stem Cells / Q000187:drug effects / Q000201:enzymology / Q000528:radiation effects; D014466:Ultraviolet Rays; D014965:X-Rays; D000099270:Y-Family DNA Polymerases
chemical_list: D001564:Benzo(a)pyrene; D004247:DNA; D018736:DNA Adducts; D004259:DNA-Directed DNA Polymerase; C498613:Polk protein, mouse; D000099270:Y-Family DNA Polymerases