TCR beta and TCR alpha gene enhancers confer tissue- and stage-specificity on V(D)J recombination events.

Capone, Myriam; Watrin, Françoise; Fernex, Corinne; Horvat, Branka; Krippl, B; Wu, Li; Scollay, Roland; Ferrier, Pierre

doi:10.1002/j.1460-2075.1993.tb06118.x

Cited by 125 publications

(109 citation statements)

References 64 publications

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“…However, these studies were unable to directly modulate transcription or methylation but instead relied on alterations of the substrate and subsequent analysis of transcription, methylation, and recombination. Some substrates did have discordant effects on these properties; whereas some substrates were transcriptionally active but recombinationally silent (34,35), others were transcriptionally silent but recombinationally active (36). Additionally, a genetically modified heavy chain locus was developmentally demethylated but recombinationally silent (37).…”

Section: Discussionmentioning

confidence: 99%

V(D)J recombination is not activated by demethylation of the kappa locus

Cherry

Beard

Jaenisch

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

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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.T he V(D)J recombination machinery assembles antigen receptor genes during lymphoid development from gene segments flanked by recombination signal sequences (1). This nonhomologous site-specific recombination process is precisely controlled by a number of different regulatory mechanisms. For one thing, the coexpression of the lymphoid-specific Rag-1 and Rag-2 genes occurs restrictively in developing B and T cells, ensuring that only the appropriate cell types are recombinationally active (2). A second level of regulation also controls lineage specificity: complete Ig gene rearrangement occurs only in B cells, whereas T cell receptor genes rearrange exclusively in T cells (3). Moreover, within developing B and T cells there are temporal controls over specific gene segment usage (4, 5). Additionally, allelic exclusion ensures that each B or T cell generates only one functional antigen receptor even though two alleles exist at each locus (6).This remarkable ability of the recombination machinery to target only a very small subset of substrates within a given cell together with the fact that a single recombinase is required for this process has led to the hypothesis that the accessibility of DNA targets to the recombination machinery is tightly controlled (7-9). Recombination loci are thought to be inaccessible until they are modified to allow the recombination machinery access to target sites. Changes in chromatin structure, transcriptional activity, or DNA methylation at each locus have been identified that correlate with recombinational activity. Many studies have attempted to define the cis-acting sequences and trans-acting factors required to regulate this process. Distinct enhancer sequences present within individual loci must be controlled by different trans-acting proteins to allow developmentally regulated changes in the accessibility of each locus to occur.DNA methylation has been shown to regulate chromatin structure, leading to changes of gene expression (10). Additionally, methylation has been correlated with Ig gene regulation: both the heavy chain and light chain are hypermethylated in cells in which they are not recombined (11,12). Concomitant with V(D)J rearrang...

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Section: Discussionmentioning

confidence: 99%

V(D)J recombination is not activated by demethylation of the kappa locus

Cherry

Beard

Jaenisch

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

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“…This may result from the inactivity of E␣ in DN thymocytes (11,14). However, E␦ is active in DN thymocytes and promotes the accessibility of TCR␦ gene segments, including V␦5 (see Results), that lie immediately Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110 upstream of the TEA promoter (2,15).…”

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confidence: 96%

Developmental Stage-Specific Regulation of TCR-α-Chain Gene Assembly by Intrinsic Features of the TEA Promoter

Huang

Sleckman

2007

The Journal of Immunology

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The TCR δ- and α-chain genes lie in a single complex locus, the TCRα/δ locus. TCRδ-chain genes are assembled in CD4−CD8− (double negative (DN)) thymocytes and TCRα-chain genes are assembled in CD4+CD8+ (double positive) thymocytes due, in part, to the developmental stage-specific activities of the TCRδ and TCRα enhancers (Eδ and Eα), respectively. Eδ functions with TCRδ promoters to mediate TCRδ-chain gene assembly in DN thymocytes. However, Eδ is unable to function with TCRα promoters such as the TEA promoter to drive TCRα-chain gene assembly in these cells. This is important, because the premature assembly of TCRα-chain genes in DN thymocytes would disrupt αβ and γδ T cell development. The basis for TEA inactivity in DN thymocytes is unclear, because Eδ can activate the Vδ5 gene segment promoter that lies only 4 kb upstream of TEA promoter. In this study, we use gene targeting to construct a modified TCRα/δ locus (TCRα/δ5ΔT) in which the TEA promoter lies in the same location as the Vδ5 gene segment on the wild-type TCRα/δ allele. Remarkably, the TEA promoter on this allele exhibits normal developmental stage-specific regulation, being active in double positive thymocytes but not in DN thymocytes as is the case with the Vδ5 promoter. Thus, the inactivity of the TEA promoter in DN thymocytes is due primarily to intrinsic developmental stage-specific features of the promoter itself and not to its location relative to other cis-acting elements in the locus, such as Eδ.

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“…In transgenic assays the TCR␤ and ␣ enhancers closely recapitulate early and late activation of these genes, respectively (33,34). Therefore, it is interesting to compare the organization of the core domains of the ␣ and ␤ enhancers (Fig.…”

Section: Figurementioning

confidence: 99%

Functional Analysis of the Murine TCRβ-Chain Gene Enhancer

Carvajal

Sen

2000

The Journal of Immunology

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The TCRβ-chain gene enhancer activates transcription and V(D)J recombination in immature thymocytes. In this paper we present a systematic analysis of the elements that contribute to the activity of the murine TCRβ enhancer in mature and immature T cell lines. We identified a region containing the βE4, βE5, and βE6 motifs as the essential core of the TCRβ enhancer in pro-T cells. In mature cells, the core enhancer had low activity and required, in addition, either 5′ or 3′ flanking sequences whose functions may be partially overlapping. Mutation of any of the six protein binding sites located within the βE4–βE6 elements essentially abolished enhancer activity, indicating that this core enhancer contained no redundant elements. The βE4 and βE6 elements contain binding sites for ETS-domain proteins and the core binding factor. The βE5 element bound two proteins that could be resolved chromatographically and that were both essential for enhancer activity.

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TCR beta and TCR alpha gene enhancers confer tissue- and stage-specificity on V(D)J recombination events.

Cited by 125 publications

References 64 publications

V(D)J recombination is not activated by demethylation of the kappa locus

V(D)J recombination is not activated by demethylation of the kappa locus

Developmental Stage-Specific Regulation of TCR-α-Chain Gene Assembly by Intrinsic Features of the TEA Promoter

Functional Analysis of the Murine TCRβ-Chain Gene Enhancer

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