Definition of a T-Cell Receptor β Gene Core Enhancer of V(D)J Recombination by Transgenic Mapping

• DOI: 10.1128/mcb.20.1.42-53.2000
• Publication Date: 2009-04-22T02:32:04Z
• Authors: Raj Kamal Tripathi; Noëlle Mathieu; Salvatore Spicuglia; Dominique Payet; Christophe Verthuy; Gaëlle Bouvier; Danielle Depetris; Marie-Geneviève M...; William M. HempeL; Pierre Ferrier
• Keywords: Recombination, Genetic; 0301 basic medicine; Base Sequence; Genes, Immunoglobulin; [SDV]Life Sciences [q-bio]; Receptors, Antigen, T-Cell, alpha-beta; T-Lymphocytes; Molecular Sequence Data; Immunoglobulin Variable Region; Mice, Transgenic; [SDV] Life Sciences [q-bio]; Mice; 03 medical and health sciences; Immunoglobulin J-Chains; Animals; Gene Rearrangement, beta-Chain T-Cell Antigen Receptor

V(D)J recombination in differentiating lymphocytes is a highly regulated process in terms of both cell lineage and the stage of cell development. Transgenic and knockout mouse studies have demonstrated that transcriptional enhancers from antigen receptor genes play an important role in this regulation by activating cis-recombination events. A striking example is the T-cell receptor beta-chain (TCRbeta) gene enhancer (Ebeta), which in the mouse consists of at least seven nuclear factor binding motifs (betaE1 to betaE7). Here, using a well-characterized transgenic recombination substrate approach, we define the sequences within Ebeta required for recombination enhancer activity. The Ebeta core is comprised of a limited set of motifs (betaE3 and betaE4) and an additional previously uncharacterized 20-bp sequence 3' of the betaE4 motif. This core element confers cell lineage- and stage-specific recombination within the transgenic substrates, although it cannot bypass the suppressive effects resulting from transgene integration in heterochromatic centromeres. Strikingly, the core enhancer is heavily occupied by nuclear factors in immature thymocytes, as shown by in vivo footprinting analyses. A larger enhancer fragment including the betaE1 through betaE4 motifs but not the 3' sequences, although active in inducing germ line transcription within the transgenic array, did not retain the Ebeta recombinational activity. Our results emphasize the multifunctionality of the TCRbeta enhancer and shed some light on the molecular mechanisms by which transcriptional enhancers and associated nuclear factors may impact on cis recombination, gene expression, and lymphoid cell differentiation.