Developmental regulation of VDJ recombination by the core fragment of the T cell receptor alpha enhancer.
The role of T cell receptor alpha enhancer (E alpha) cis-acting elements in the developmental regulation of VDJ recombination at the TCR alpha/delta locus was examined in transgenic mice containing variants of a minilocus VDJ recombination substrate. We demonstrate that the 116-bp T alpha 1,2 core enhancer fragment of the 1.4-kb E alpha is sufficient to activate the enhancer-dependent step of minilocus rearrangement, and that within T alpha 1,2, intact binding sites for TCF/LEF and Ets family transcription factors are essential. Although minilocus rearrangement under the control of the 1.4-kb E alpha initiates at fetal day 16.5 and is strictly limited to alpha beta T cells, we find that rearrangement under the control of T alpha 1,2 initiates slightly earlier during ontogeny and occurs in both gamma delta and alpha beta T cells. We conclude that the core fragment of E alpha can establish accessibility to the recombinase in developing thymocytes in vivo in a fashion that is dependent on the binding of TCF/LEF and Ets family transcription factors, but that these and other factors that bind to the E alpha core cannot account for the precise developmental onset of accessibility that is provided by the intact E alpha. Rather, our data suggests a critical role for factors that bind E alpha outside of the core T alpha 1,2 region in establishing the precise developmental onset of TCR alpha rearrangement in vivo.
Roberts
J L
JL
Department of Immunology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Lauzurica
P
P
Krangel
M S
MS
D000818:Animals; D001483:Base Sequence; D004254:DNA Nucleotidyltransferases / Q000378:metabolism; D017931:DNA Primers; D004742:Enhancer Elements, Genetic; D005434:Flow Cytometry; D016694:Gene Rearrangement, delta-Chain T-Cell Antigen Receptor; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000096:biosynthesis / Q000235:genetics*; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000096:biosynthesis / Q000235:genetics*; D013601:T-Lymphocytes / Q000276:immunology*; D045567:VDJ Recombinases
D017931:DNA Primers; D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta; D004254:DNA Nucleotidyltransferases; D045567:VDJ Recombinases