The translesion DNA polymerase theta plays a dominant role in immunoglobulin gene somatic hypermutation.
Immunoglobulin (Ig) somatic hypermutation (SHM) critically underlies the generation of high-affinity antibodies. Mutations can be introduced by error-prone polymerases such as polymerase zeta (Rev3), a mispair extender, and polymerase eta, a mispair inserter with a preference for dA/dT, while repairing DNA lesions initiated by AID-mediated deamination of dC to yield dU:dG mismatches. The partial impairment of SHM observed in the absence of these polymerases led us to hypothesize a main role for another translesion DNA polymerase. Here, we show that deletion in C57BL/6J mice of the translesion polymerase theta, which possesses a dual nucleotide mispair inserter-extender function, results in greater than 60% decrease of mutations in antigen-selected V186.2DJ(H) transcripts and greater than 80% decrease in mutations in the Ig H chain intronic J(H)4-iEmu sequence, together with significant alterations in the spectrum of the residual mutations. Thus, polymerase theta plays a dominant role in SHM, possibly by introducing mismatches while bypassing abasic sites generated by UDG-mediated deglycosylation of AID-effected dU, by extending DNA past such abasic sites and by synthesizing DNA during dU:dG mismatch repair.
Zan
Hong
H
Center for Immunology, School of Medicine and School of Biological Sciences, University of California, Irvine, CA, USA.
Shima
Naoko
N
Xu
Zhenming
Z
Al-Qahtani
Ahmed
A
Evinger Iii
Albert J
AJ
Zhong
Yuan
Y
Schimenti
John C
JC
Casali
Paolo
P
D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology; D001483:Base Sequence; D003564:Cytidine Deaminase; D004260:DNA Repair; D004259:DNA-Directed DNA Polymerase / Q000502:physiology*; D017353:Gene Deletion; D005803:Genes, Immunoglobulin; D007074:Immunoglobulin G / Q000235:genetics*; D007133:Immunoglobulin Joining Region / Q000235:genetics; D007135:Immunoglobulin Variable Region / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D009154:Mutation; D012333:RNA, Messenger / Q000235:genetics / Q000302:isolation & purification; D027041:Somatic Hypermutation, Immunoglobulin; D013601:T-Lymphocytes / Q000276:immunology; D000097462:DNA Polymerase theta
D003564:Cytidine Deaminase; D004259:DNA-Directed DNA Polymerase; D007074:Immunoglobulin G; D007133:Immunoglobulin Joining Region; D007135:Immunoglobulin Variable Region; D012333:RNA, Messenger; D000097462:DNA Polymerase theta