Genetic analysis reveals an intrinsic property of the germinal center B cells to generate A:T mutations

Rika Ouchida, Akiko Ukai, Hiromi Mori, Kiyoko Kawamura, Martijn E.T. Dollé, Masatoshi Tagawa, Akemi Sakamoto, Takeshi Tokuhisa, Tadashi Yokosuka, Takashi Saito, Masayuki Yokoi, Fumio Hanaoka, Jan Vijg, Ji Yang Wang

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


The immunoglobulin genes undergo a high frequency of point mutations at both C:G and A:T pairs in the germinal center (GC) B cells. This hypermutation process is initiated by the activation-induced cytidine deaminase (AID), which converts cytosine to uracil and generates a U:G lesion. Replication of this lesion, or its repair intermediate the abasic site, could introduce C:G mutations but the mechanisms leading to mutations at non-damaged A:T pairs remain elusive. Using a lacZ-transgenic system in which endogenous genome mutations can be detected with high sensitivity, we found that GC B cells exhibited a much higher ratio of A:T mutations as compared to naïve B, non-GC B, and cells of other tissues. This property does not require AID or active transcription of the target gene, and is dependent on DNA polymerase η. These in vivo results demonstrate that GC B cells are unique in having an intrinsic propensity to generate A:T mutations during repair of endogenous DNA damage. These findings have important implications in understanding how AID, which can only target C:G base pairs, is able to induce the entire spectrum of mutations observed in immunoglobulin variable region genes in GC B cells.

Original languageEnglish (US)
Pages (from-to)1392-1398
Number of pages7
JournalDNA Repair
Issue number8
StatePublished - Aug 2 2008
Externally publishedYes


  • Activation-induced cytidine deaminase
  • DNA polymerase η
  • Genome mutation
  • Germinal center B cells
  • Mismatch repair

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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