V(D)J recombination is not activated by demethylation of the kappa locus.
V(D)J recombination is thought to be regulated by changes in the accessibility of target sites, such as modulation of methylation. To test whether demethylation of the kappa locus can activate recombination, we generated two recombinationally active B cell lines in which the gene for maintenance of genomic DNA methylation, Dnmt1, was flanked with loxP sites. Transduction with a retrovirus expressing both the cre recombinase and green fluorescent protein allowed us to purify recombinationally active cells devoid of methylation. Loss of methylation of the kappa locus was not sufficient to activate recombination, although transcription was activated in one line. It appears that demethylation of the kappa locus is not the rate-limiting step for altering accessibility and thus regulated demethylation does not generate specificity of recombination.
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The Whitehead Institute, 9 Cambridge Center, Cambridge, MA 02142, USA.
Beard
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Jaenisch
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Baltimore
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D000818:Animals; D001402:B-Lymphocytes; D002461:Cell Line, Transformed; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics; D019175:DNA Methylation; D004254:DNA Nucleotidyltransferases / Q000378:metabolism; D015328:Gene Rearrangement, B-Lymphocyte, Light Chain; D005803:Genes, Immunoglobulin; D007145:Immunoglobulin kappa-Chains / Q000235:genetics*; D019426:Integrases; D051379:Mice; D011995:Recombination, Genetic; D015533:Transcriptional Activation; D045567:VDJ Recombinases; D014764:Viral Proteins
D007145:Immunoglobulin kappa-Chains; D014764:Viral Proteins; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; C000619381:Dnmt1 protein, mouse; C045073:Cre recombinase; D004254:DNA Nucleotidyltransferases; D019426:Integrases; D045567:VDJ Recombinases