title: DNA polymerases nu and theta are required for efficient immunoglobulin V gene diversification in chicken.
abstract: The chicken DT40 B lymphocyte line diversifies its immunoglobulin (Ig) V genes through translesion DNA synthesis-dependent point mutations (Ig hypermutation) and homologous recombination (HR)-dependent Ig gene conversion. The error-prone biochemical characteristic of the A family DNA polymerases Polnu and Pol led us to explore the role of these polymerases in Ig gene diversification in DT40 cells. Disruption of both polymerases causes a significant decrease in Ig gene conversion events, although POLN(-/-)/POLQ(-/-) cells exhibit no prominent defect in HR-mediated DNA repair, as indicated by no increase in sensitivity to camptothecin. Poleta has also been previously implicated in Ig gene conversion. We show that a POLH(-/-)/POLN(-/-)/POLQ(-/-) triple mutant displays no Ig gene conversion and reduced Ig hypermutation. Together, these data define a role for Polnu and Pol in recombination and suggest that the DNA synthesis associated with Ig gene conversion is accounted for by three specialized DNA polymerases.
authors.affiliation: Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Masaoki
authors.initials: M
authors.lastname: Kohzaki
authors.forename: Kana
authors.initials: K
authors.lastname: Nishihara
authors.forename: Kouji
authors.initials: K
authors.lastname: Hirota
authors.forename: Eiichiro
authors.initials: E
authors.lastname: Sonoda
authors.forename: Michio
authors.initials: M
authors.lastname: Yoshimura
authors.forename: Shigeo
authors.initials: S
authors.lastname: Ekino
authors.forename: John E
authors.initials: JE
authors.lastname: Butler
authors.forename: Masami
authors.initials: M
authors.lastname: Watanabe
authors.forename: Thanos D
authors.initials: TD
authors.lastname: Halazonetis
authors.forename: Shunichi
authors.initials: S
authors.lastname: Takeda
mesh_terms: D000818:Animals; D002460:Cell Line; D002645:Chickens; D004260:DNA Repair; D004259:DNA-Directed DNA Polymerase / Q000235:genetics*; D005785:Gene Conversion; D014644:Genetic Variation; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D008214:Lymphocytes; D017354:Point Mutation; D011995:Recombination, Genetic; D027041:Somatic Hypermutation, Immunoglobulin; D000097462:DNA Polymerase theta
chemical_list: D004259:DNA-Directed DNA Polymerase; D007135:Immunoglobulin Variable Region; D000097462:DNA Polymerase theta