Bouvier G, Watrin F, Naspetti M, Verthuy C, Naquet P, Ferrier P
Centre d'Immunologie de Marseille-Luminy, Institut National de la Santé et de la Recherche Médicale-Centre National de la Recherche Scientifique, France.
Proc Natl Acad Sci U S A. 1996 Jul 23;93(15):7877-81. doi: 10.1073/pnas.93.15.7877.
Intrathymic T-cell development requires temporally regulated rearrangement and expression of T-cell receptor (TCR) genes. To assess the role of the TCR beta gene transcriptional enhancer (Ebeta) in this process, mouse strains in which Ebeta is deleted were generated using homologous recombination techniques. We report that mice homozygous for the Ebeta deletion, whether a selectable marker gene is present or not, show a block in alphabeta T-cell development at the CD4-CD8- double-negative cell stage, whereas the number of gammadelta+ T cells is normal, few CD4+CD8+ double-positive thymocytes and no alphabeta+ T cells are produced. DNA-PCR and RNA-PCR analyses of thymic cells from homozygous mutants showed no evidence of TCR beta gene rearrangement although germ-line Vbeta transcripts were detected at a low level, in heterozygous T cells, the targeted allele is not rearranged. Thus, deletion of Ebeta totally prevents rearrangement, but not transcription, of the targeted beta locus. These data formally establish the critical role played by Ebeta in cis-activation of the TCR beta locus for V(D)J recombination during alphabeta T-cell development.
胸腺内T细胞的发育需要T细胞受体（TCR）基因在时间上受到调控的重排和表达。为了评估TCRβ基因转录增强子（Eβ）在此过程中的作用，利用同源重组技术构建了Eβ缺失的小鼠品系。我们报告称，无论是否存在选择标记基因，Eβ缺失的纯合小鼠在CD4-CD8-双阴性细胞阶段的αβT细胞发育均出现阻滞，而γδ+ T细胞数量正常，几乎没有产生CD4+CD8+双阳性胸腺细胞，也没有αβ+ T细胞。对纯合突变体胸腺细胞进行的DNA-PCR和RNA-PCR分析显示，尽管在低水平检测到种系Vβ转录本，但没有TCRβ基因重排的证据；在杂合T细胞中，靶向等位基因没有重排。因此，Eβ的缺失完全阻止了靶向β基因座的重排，但不影响其转录。这些数据正式确立了Eβ在αβT细胞发育过程中对TCRβ基因座进行V（D）J重组的顺式激活中所起的关键作用。
