Target specificity of immunoglobulin class switch recombination is not determined by nucleotide sequences of S regions.
We describe a model system for class switch recombination (CSR) using CH12F3-2 cells transfected with a DNA construct containing two S sequences transcribed by different promoters and separated by a viral thymidine kinase (TK) gene. Recombination observed using this system shares key properties with physiological CSR: deletion of DNA between two S regions, requirement for cytokine stimulation, and nonhomologous and no consensus breakpoint sequences. Studies on transfectants with variants of this construct led us to the following conclusions: (1) two S sequences are required for CSR; (2) isotype specificity of recombination is not determined by nucleotide sequences of S regions; (3) S sequences are not strand-specific; and (4) induction of recombination activity requires cytokine stimulation.
Kinoshita
K
K
Department of Medical Chemistry, Kyoto University Faculty of Medicine, Japan.
Tashiro
J
J
Tomita
S
S
Lee
C G
CG
Honjo
T
T
D000818:Animals; D001483:Base Sequence; D023201:CD40 Ligand; D002460:Cell Line; D004351:Drug Resistance; D015774:Ganciclovir / Q000494:pharmacology; D017578:Immunoglobulin Class Switching / Q000235:genetics*; D007134:Immunoglobulin Switch Region / Q000235:genetics* / Q000276:immunology; D007137:Immunoglobulin alpha-Chains / Q000235:genetics*; D007148:Immunoglobulin mu-Chains / Q000235:genetics*; D015847:Interleukin-4 / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000494:pharmacology; D051379:Mice; D008969:Molecular Sequence Data; D011995:Recombination, Genetic; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D007137:Immunoglobulin alpha-Chains; D007148:Immunoglobulin mu-Chains; D008562:Membrane Glycoproteins; D016212:Transforming Growth Factor beta; D023201:CD40 Ligand; D015847:Interleukin-4; D015774:Ganciclovir