Position-dependent silencing of germline Vß segments on TCRß alleles containing preassembled VßDJßCß1 genes.
The genomic organization of TCRbeta loci enables Vbeta-to-DJbeta2 rearrangements on alleles with assembled VbetaDJbetaCbeta1 genes, which could have deleterious physiologic consequences. To determine whether such Vbeta rearrangements occur and, if so, how they might be regulated, we analyzed mice with TCRbeta alleles containing preassembled functional VbetaDJbetaCbeta1 genes. Vbeta10 segments were transcribed, rearranged, and expressed in thymocytes when located immediately upstream of a Vbeta1DJbetaCbeta1 gene, but not on alleles with a Vbeta14DJbetaCbeta1 gene. Germline Vbeta10 transcription was silenced in mature alphabeta T cells. This allele-dependent and developmental stage-specific silencing of Vbeta10 correlated with increased CpG methylation and decreased histone acetylation over the Vbeta10 promoter and coding region. Transcription, rearrangement, and expression of the Vbeta4 and Vbeta16 segments located upstream of Vbeta10 were silenced on alleles containing either VbetaDJbetaCbeta1 gene; sequences within Vbeta4, Vbeta16, and the Vbeta4/Vbeta16-Vbeta10 intergenic region exhibited constitutive high CpG methylation and low histone acetylation. Collectively, our data indicate that the position of Vbeta segments relative to assembled VbetaDJbetaCbeta1 genes influences their rearrangement and suggest that DNA sequences between Vbeta segments may form boundaries between active and inactive Vbeta chromatin domains upstream of VbetaDJbetaCbeta genes.
Brady
Brenna L
BL
Immunology Graduate Group, Department of Pathology and Laboratory Medicine, Center for Childhood Cancer Research, Children's Hospital of Philadelphia, Philadelphia, PA 19104 USA.
Oropallo
Michael A
MA
Yang-Iott
Katherine S
KS
Serwold
Thomas
T
Hochedlinger
Konrad
K
Jaenisch
Rudolf
R
Weissman
Irving L
IL
Bassing
Craig H
CH
D000483:Alleles; D000818:Animals; D002843:Chromatin / Q000737:chemistry / Q000235:genetics; D015333:Gene Rearrangement, beta-Chain T-Cell Antigen Receptor / Q000276:immunology*; D020868:Gene Silencing / Q000276:immunology*; D019674:Genes, T-Cell Receptor beta / Q000502:physiology*; D018095:Germ-Line Mutation / Q000276:immunology*; D018398:Homeodomain Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics; D006825:Hybridomas; D007135:Immunoglobulin Variable Region / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D007165:Immunosuppression Therapy / Q000379:methods; D051379:Mice; D018345:Mice, Knockout; D010446:Peptide Fragments / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics*; D014158:Transcription, Genetic / Q000276:immunology
D002843:Chromatin; D018398:Homeodomain Proteins; D007135:Immunoglobulin Variable Region; D010446:Peptide Fragments; D016693:Receptors, Antigen, T-Cell, alpha-beta; C064658:RAG-1 protein