AID binds cooperatively with UNG and Msh2-Msh6 to Ig switch regions dependent upon the AID C terminus
Department of Microbiology and Physiological Systems
Medical Subject Headings
Animals; B-Lymphocytes; Cell Separation; Chromatin Immunoprecipitation; Cytidine Deaminase; DNA-Binding Proteins; Flow Cytometry; Immunoglobulin Class Switching; Immunoglobulin G; Immunoglobulin Switch Region; Mice; Mice, Inbred C57BL; Mice, Knockout; MutS Homolog 2 Protein; Protein Binding; Reverse Transcriptase Polymerase Chain Reaction; Uracil-DNA Glycosidase
Genetics and Genomics | Immunology and Infectious Disease
Activation-induced cytidine deaminase (AID) is induced in B cells during an immune response and is essential for both class-switch recombination (CSR) and somatic hypermutation of Ab genes. The C-terminal 10 aa of AID are required for CSR but not for somatic hypermutation, although their role in CSR is unknown. Using retroviral transduction into mouse splenic B cells, we show that the C terminus is not required for switch (S) region double-strand breaks (DSBs) and therefore functions downstream of DSBs. Using chromatin immunoprecipitation, we show that AID binds cooperatively with UNG and the mismatch repair proteins Msh2-Msh6 to Ig Smu and Sgamma3 regions, and this depends on the C terminus and the deaminase activity of AID. We also show that mismatch repair does not contribute to the efficiency of CSR in the absence of the AID C terminus. Although it has been demonstrated that both UNG and Msh2-Msh6 are important for introduction of S region DSBs, our data suggest that the ability of AID to recruit these proteins is important for DSB resolution, perhaps by directing the S region DSBs toward accurate and efficient CSR via nonhomologous end joining.
Ranjit, Sanjay; Khair, Lyne; Linehan, Erin K.; Ucher, Anna J.; Chakrabarti, Mrinmay; Schrader, Carol E.; and Stavnezer, Janet, "AID binds cooperatively with UNG and Msh2-Msh6 to Ig switch regions dependent upon the AID C terminus" (2011). Microbiology and Physiological Systems Publications and Presentations. 4.