Carding S R, Kyes S, Jenkinson E J, Kingston R, Bottomly K, Owen J J, Hayday A C
Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut.
Genes Dev. 1990 Aug;4(8):1304-15. doi: 10.1101/gad.4.8.1304.
The gamma delta T-cell receptor (TCR) is the first TCR to be expressed in ontogeny in all vertebrates in which it has been examined thoroughly. Murine gamma delta cell-surface protein is detected by the fourteenth day of gestation. In this work, the activation of gamma delta RNA has been studied. Data indicate that the first TCR protein to appear in the thymus is encoded by gamma genes that are activated after cells colonize the thymus. However, the sequential appearance of different gamma delta TCR proteins during thymic ontogeny cannot be readily explained by differential temporal activation of V gamma genes in the thymus. There are distinct patterns of gamma and delta gene expression during fetal liver development and in the fetal gut (or tissue associated with it). Cells apparent in the liver of mice at birth express gamma delta cell-surface protein, but they disappear from the liver very soon afterward. One V gamma gene is rearranged and expressed prethymically. In addition, gamma gene expression is detectable in the livers of newborn athymic mice. Together, these observations indicate a thymic-independent pathway of activation of TCR genes.
γδ T细胞受体（TCR）是所有已被深入研究的脊椎动物个体发育过程中最早表达的TCR。在妊娠第14天时可检测到小鼠γδ细胞表面蛋白。在这项研究中，对γδ RNA的激活进行了研究。数据表明，胸腺中最早出现的TCR蛋白是由细胞定殖于胸腺后被激活的γ基因编码的。然而，胸腺个体发育过程中不同γδ TCR蛋白的顺序出现，不能简单地用胸腺中Vγ基因的不同时间激活来解释。在胎儿肝脏发育过程中和胎儿肠道（或与之相关的组织）中，γ和δ基因存在不同的表达模式。出生时小鼠肝脏中出现的细胞表达γδ细胞表面蛋白，但随后很快从肝脏中消失。一个Vγ基因在胸腺前就发生重排并表达。此外，在新生无胸腺小鼠的肝脏中也可检测到γ基因的表达。这些观察结果共同表明了一条不依赖胸腺的TCR基因激活途径。
