Abstract
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.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Alleles
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Animals
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B-Lymphocytes / cytology
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B-Lymphocytes / immunology*
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Cell Division
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Cells, Cultured
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DNA-Activated Protein Kinase
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DNA-Binding Proteins*
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Female
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Immunoglobulin Class Switching / genetics*
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Immunoglobulin Constant Regions / genetics
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Immunoglobulin G / blood
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Immunoglobulin G / genetics*
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Immunoglobulin Heavy Chains / genetics*
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Immunoglobulin Isotypes
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Immunoglobulin Light Chains
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Immunoglobulin M / blood
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Lymphocyte Activation
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Male
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Mice
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Mice, Knockout
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Mice, Transgenic
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Protein Serine-Threonine Kinases / genetics
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Protein Serine-Threonine Kinases / physiology*
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Recombination, Genetic
Substances
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DNA-Binding Proteins
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Immunoglobulin Constant Regions
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Immunoglobulin G
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Immunoglobulin Heavy Chains
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Immunoglobulin Isotypes
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Immunoglobulin Light Chains
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Immunoglobulin M
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DNA-Activated Protein Kinase
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Protein Serine-Threonine Kinases