Allelic exclusion of IgH through inhibition of E2A in a VDJ recombination complex.
A key feature of the immune system is the paradigm that one lymphocyte has only one Ag specificity that can be selected for or against. This requires that only one of the alleles of genes for AgR chains is made functional. However, the molecular mechanism of this allelic exclusion has been an enigma. In this study, we show that B lymphocytes with E2A that cannot be inhibited by calmodulin are dramatically defective in allelic exclusion of the IgH locus. Furthermore, we provide data supporting that E2A, PAX5, and the RAGs are in a VDJ recombination complex bound to key sequences on the Igh gene. We show that pre-BCR activation releases the VDJ recombination complex through calmodulin binding to E2A. We also show that pre-BCR signaling downregulates several components of the recombination machinery, including RAG1, RAG2, and PAX5, through calmodulin inhibition of E2A.
Department of Molecular Biology, Umeå University, SE-901 87 Umeå, Sweden.
Jannek
J
Hauser
Christine
C
Grundström
Thomas
T
Grundström
D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000276:immunology; D056426:Genetic Loci / Q000276:immunology*; D018398:Homeodomain Proteins / Q000235:genetics / Q000276:immunology; D007143:Immunoglobulin Heavy Chains / Q000235:genetics / Q000276:immunology*; D051379:Mice; D018345:Mice, Knockout; D051757:PAX5 Transcription Factor / Q000235:genetics / Q000276:immunology; D011947:Receptors, Antigen, B-Cell / Q000235:genetics / Q000276:immunology*; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology*; D060152:V(D)J Recombination / Q000235:genetics / Q000276:immunology*
D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D007143:Immunoglobulin Heavy Chains; D051757:PAX5 Transcription Factor; D011947:Receptors, Antigen, B-Cell; C497282:Pax5 protein, mouse; C499308:Rag2 protein, mouse; C075668:Tcf3 protein, mouse; C064658:RAG-1 protein