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DNA polymerases ν and θ are required for efficient immunoglobulin V gene diversification in chicken

2010; Rockefeller University Press; Volume: 189; Issue: 7 Linguagem: Inglês

10.1083/jcb.200912012

1540-8140

Masaoki Kohzaki, Kana Nishihara, Kouji Hirota, Eiichiro Sonoda, Michio Yoshimura, Shigeo Ekino, John E. Butler, Masami Watanabe, Thanos D. Halazonetis, Shunichi Takeda,

Immune Cell Function and Interaction

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 Polν and Polθ 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. Polη 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 Polν and Polθ in recombination and suggest that the DNA synthesis associated with Ig gene conversion is accounted for by three specialized DNA polymerases.