IgH class switch recombination to IgG1 in DNA-PKcs-deficient B cells.
To assess the role of the DNA-PKcs nonhomologous DNA end-joining (NHEJ) protein in Ig heavy chain class switch recombination (CSR), we assayed CSR ability of DNA-PKcs-deficient (DP-T) B cells generated via complementation of DP-T mice with Ig heavy chain and light chain knock-in transgenes (DP-T/HC/LC mice). DP-T/HC/LC mice were severely deficient for all serum IgH isotypes except IgM and, unexpectedly, IgG1. Upon appropriate stimulation, DP-T/HC/LC B cells showed normal proliferation, germline C(H) gene transcription, and AID induction, indicating that DNA-PKcs deficiency did not affect cellular events upstream to CSR. Yet, in vitro activated DP-T/HC/LC B cells again underwent switching only to IgG1 and, like wild-type cells, frequently underwent CSR to gamma1 on both chromosomes. We conclude that DNA-PKcs is required for CSR to most C(H) genes but that CSR to gamma1 occurs via a DNA-PKcs-independent mechanism.
Manis
John P
JP
Howard Hughes Medical Institute and Children's Hospital, Center for Blood Research and Department of Genetics, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA.
Dudley
Darryll
D
Kaylor
Lianne
L
Alt
Frederick W
FW
D000483:Alleles; D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D002455:Cell Division; D002478:Cells, Cultured; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins; D005260:Female; D017578:Immunoglobulin Class Switching / Q000235:genetics*; D007127:Immunoglobulin Constant Regions / Q000235:genetics; D007074:Immunoglobulin G / Q000097:blood / Q000235:genetics*; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007132:Immunoglobulin Isotypes; D007147:Immunoglobulin Light Chains; D007075:Immunoglobulin M / Q000097:blood; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000502:physiology*; D011995:Recombination, Genetic
D004268:DNA-Binding Proteins; D007127:Immunoglobulin Constant Regions; D007074:Immunoglobulin G; D007143:Immunoglobulin Heavy Chains; D007132:Immunoglobulin Isotypes; D007147:Immunoglobulin Light Chains; D007075:Immunoglobulin M; D051747:DNA-Activated Protein Kinase; D017346:Protein Serine-Threonine Kinases