MicroRNA-155 is a negative regulator of activation-induced cytidine deaminase

Immunity. 2008 May;28(5):621-9. doi: 10.1016/j.immuni.2008.03.015. Epub 2008 May 1.


B lymphocytes perform somatic hypermutation and class-switch recombination (CSR) of the immunoglobulin locus to generate an antibody repertoire diverse in both affinity and function. These somatic diversification processes are catalyzed by activation-induced cytidine deaminase (AID), a potent DNA mutator whose expression and function are highly regulated. Here we show that AID was regulated posttranscriptionally by a lymphocyte-specific microRNA, miR-155. We found that miR-155 was upregulated in murine B lymphocytes undergoing CSR and that it targeted a conserved site in the 3'-untranslated region of the mRNA encoding AID. Disruption of this target site in vivo resulted in quantitative and temporal deregulation of AID expression, along with functional consequences for CSR and affinity maturation. Thus, miR-155, which has recently been shown to play important roles in regulating the germinal-center reaction, does so in part by directly downmodulating AID expression.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3' Untranslated Regions
  • Animals
  • B-Lymphocytes / enzymology*
  • B-Lymphocytes / immunology
  • B-Lymphocytes / metabolism
  • Cells, Cultured
  • Cytidine Deaminase / genetics*
  • Cytidine Deaminase / metabolism*
  • Immunoglobulin Class Switching
  • Lipopolysaccharides / immunology
  • Mice
  • Mice, Mutant Strains
  • Mice, Transgenic
  • MicroRNAs / genetics
  • MicroRNAs / immunology
  • MicroRNAs / metabolism*
  • Mutation
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Somatic Hypermutation, Immunoglobulin


  • 3' Untranslated Regions
  • Lipopolysaccharides
  • MicroRNAs
  • RNA, Messenger
  • AICDA (activation-induced cytidine deaminase)
  • Cytidine Deaminase