Control of V(D)J recombinational accessibility of the D beta 1 gene segment at the TCR beta locus by a germline promoter.
The germline promoter region upstream of the D beta 1 gene segment in the murine TCR beta locus was deleted to assess its role in controlling V(D)J recombination. Associated with diminished D beta 1 region germline transcription, rearrangement of the D beta 1 but not the D beta 2 gene segment was reduced 10- to 20-fold. A corresponding reduction in RAG-mediated cleavage at the D beta 1 and J beta 1 signal sequences was apparent only when purified CD4- CD8- thymocytes were analyzed because, as we demonstrate, cleavage at these gene segments also occurred in CD4+ CD8+ thymocytes. These findings suggest that germline promoters regulate localized accessibility of gene segments for recombination and that in CD4+ CD8+ thymocytes TCR beta allelic exclusion does not result from inaccessibility of D beta gene segments.
Whitehurst
C E
CE
Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA.
Chattopadhyay
S
S
Chen
J
J
D000818:Animals; D017353:Gene Deletion; D015329:Gene Rearrangement, T-Lymphocyte / Q000235:genetics* / Q000276:immunology; D018390:Gene Targeting; D019674:Genes, T-Cell Receptor beta / Q000235:genetics / Q000276:immunology*; D051379:Mice; D008815:Mice, Inbred Strains; D008817:Mice, Mutant Strains; D011401:Promoter Regions, Genetic / Q000276:immunology*; D011995:Recombination, Genetic / Q000276:immunology*; D014158:Transcription, Genetic / Q000276:immunology