Mutagenesis Dependent Upon the Combination of Activation-Induced Deaminase Expression and a Double-Strand Break

Mol Immunol. Nov-Dec 2010;48(1-3):164-70. doi: 10.1016/j.molimm.2010.08.013. Epub 2010 Sep 9.

Abstract

We explored DNA metabolic events potentially relevant to somatic hypermutation (SHM) of immunoglobulin genes using a yeast model system. Double-strand break (DSB) formation has been discussed as a possible component of the SHM process during immunoglobulin gene maturation. Yet, possible mechanisms linking DSB formation with mutagenesis have not been well understood. In the present study, a linkage between mutagenesis in a reporter gene and a double-strand break at a distal site was examined as a function of activation-induced deaminase (AID) expression. Induction of the DSB was found to be associated with mutagenesis in a genomic marker gene located 7 kb upstream of the break site: mutagenesis was strongest with the combination of AID expression and DSB induction. The mutation spectrum of this DSB and AID-mediated mutagenesis was characteristic of replicative bypass of uracil in one strand and was dependent on expression of DNA polymerase delta (Polδ). These results in a yeast model system illustrate that the combination of DSB induction and AID expression could be associated with mutagenesis observed in SHM. Implications of these findings for SHM of immunoglobulin genes in human B cells are discussed.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Amino Acid Transport Systems / genetics
  • Base Sequence
  • Cytidine Deaminase / biosynthesis*
  • DNA Breaks, Double-Stranded*
  • DNA Mutational Analysis
  • Fungal Proteins / genetics
  • Molecular Sequence Data
  • Mutagenesis / genetics*
  • Somatic Hypermutation, Immunoglobulin / genetics*
  • Yeasts

Substances

  • Amino Acid Transport Systems
  • CAN1 protein, Candida albicans
  • Fungal Proteins
  • AICDA (activation-induced cytidine deaminase)
  • Cytidine Deaminase