Ataxia telangiectasia mutated and MSH2 control blunt DNA end joining in Ig class switch recombination Journal Article


Authors: Sible, E.; Attaway, M.; Fiorica, G.; Michel, G.; Chaudhuri, J.; Vuong, B. Q.
Article Title: Ataxia telangiectasia mutated and MSH2 control blunt DNA end joining in Ig class switch recombination
Abstract: Class-switch recombination (CSR) produces secondary Ig isotypes and requires activation-induced cytidine deaminase (AID)–dependent DNA deamination of intronic switch regions within the IgH (Igh) gene locus. Noncanonical repair of deaminated DNA by mismatch repair (MMR) or base excision repair (BER) creates DNA breaks that permit recombination between distal switch regions. Ataxia telangiectasia mutated (ATM)–dependent phosphorylation of AID at serine 38 (pS38-AID) promotes its interaction with apurinic/ apyrimidinic endonuclease 1 (APE1), a BER protein, suggesting that ATM regulates CSR through BER. However, pS38-AID may also function in MMR during CSR, although the mechanism remains unknown. To examine whether ATM modulates BER- and/or MMR-dependent CSR, Atm2/2 mice were bred to mice deficient for the MMR gene mutS homolog 2 (Msh2). Surprisingly, the predicted Mendelian frequencies of Atm2/2Msh22/2 adult mice were not obtained. To generate ATM and MSH2-deficient B cells, Atm was conditionally deleted on an Msh22/2 background using a floxed ATM allele (Atmf) and B cell–specific Cre recombinase expression (CD23-cre) to produce a deleted ATM allele (AtmD). As compared with AtmD/D and Msh22/2 mice and B cells, AtmD/DMsh22/2 mice and B cells display a reduced CSR phenotype. Interestingly, Sl–Sg1 junctions from AtmD/DMsh22/2 B cells that were induced to switch to IgG1 in vitro showed a significant loss of blunt end joins and an increase in insertions as compared with wild-type, AtmD/D, or Msh22/2 B cells. These data indicate that the absence of both ATM and MSH2 blocks nonhomologous end joining, leading to inefficient CSR. We propose a model whereby ATM and MSH2 function cooperatively to regulate end joining during CSR through pS38-AID. Copyright © 2023 by The American Association of Immunologists, Inc.
Keywords: adult; controlled study; protein expression; gene mutation; gene deletion; genetics; nonhuman; mouse; phenotype; animal; animals; mice; mice, knockout; allele; gene; dna repair; embryo; animal experiment; animal model; gene locus; immunoglobulin; in vitro study; wild type; b lymphocyte; rna; activation induced cytidine deaminase; dna; enzyme phosphorylation; regulatory mechanism; cytidine deaminase; immunoblotting; atm protein; dna breaks, double-stranded; double stranded dna break; immunoglobulin g1; immunoglobulin class switching; gene insertion; cre recombinase; muts homolog 2 protein; knockout mouse; ataxia telangiectasia; immunization; genotyping; atm gene; base excision repair; purification; msh2 gene; b lymphocyte activation; nonhomologous end joining repair; dna end joining repair; male; female; article; dna (apurinic or apyrimidinic site) lyase; dna mismatch repair protein msh2
Journal Title: Journal of Immunology
Volume: 210
Issue: 4
ISSN: 0022-1767
Publisher: The American Association of Immunologists, Inc  
Date Published: 2023-02-15
Start Page: 369
End Page: 376
Language: English
DOI: 10.4049/jimmunol.2200590
PUBMED: 36603026
PROVIDER: scopus
PMCID: PMC9915862
DOI/URL:
Notes: Article -- Export Date: 1 March 2023 -- Source: Scopus
Altmetric
Citation Impact
BMJ Impact Analytics
MSK Authors