DNA polymerases nu and theta are required for efficient immunoglobulin V gene diversification in chicken.
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.
Kohzaki
Masaoki
M
Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
Nishihara
Kana
K
Hirota
Kouji
K
Sonoda
Eiichiro
E
Yoshimura
Michio
M
Ekino
Shigeo
S
Butler
John E
JE
Watanabe
Masami
M
Halazonetis
Thanos D
TD
Takeda
Shunichi
S
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
D004259:DNA-Directed DNA Polymerase; D007135:Immunoglobulin Variable Region; D000097462:DNA Polymerase theta