Maki K, Sunaga S, Ikuta K
Department of Disease-related Gene Regulation Research (Sandoz), Faculty of Medicine, University of Tokyo, Japan.
J Exp Med. 1996 Dec 1;184(6):2423-7. doi: 10.1084/jem.184.6.2423.
IL-7R-deficient mice have severely impaired expansion of early lymphocytes and lack gamma delta T cells. To elucidate the role of IL-7R on gamma delta T cell development, we analyzed the rearrangements of TCR-alpha, beta, gamma, and delta genes in the thymus of the IL-7R-deficient mice. Southern blot analysis with a J gamma 1 probe revealed that more than 70% of J gamma 1 and J gamma 2 alleles are recombined to form distinct V gamma 1.2-J gamma 2 and V gamma 2-J gamma 1 fragments in control mice. On the contrary, no such recombination was detected in the mutant mice. The rearrangements in the TCR-alpha, beta, and delta loci were comparably observed in control and mutant mice. PCR analysis indicated that the V-J recombination of all the V gamma genes is severely hampered in the mutant mice. The mRNA of RAG-1, RAG-2, Ku-80, and terminal deoxynucleotidyl transferase (TdT) genes was equally detected between control and mutant thymi, suggesting that the expression of common recombination machinery is not affected. These data demonstrated that the V-J recombination of the TCR gamma genes is specifically blocked in the IL-7R-deficient mice and suggested the presence of highly specific regulation for TCR gamma gene rearrangement.
白细胞介素-7受体（IL-7R）缺陷型小鼠的早期淋巴细胞扩增严重受损，且缺乏γδT细胞。为阐明IL-7R在γδT细胞发育中的作用，我们分析了IL-7R缺陷型小鼠胸腺中TCR-α、β、γ和δ基因的重排情况。用Jγ1探针进行的Southern印迹分析显示，在对照小鼠中，超过70%的Jγ1和Jγ2等位基因发生重组，形成不同的Vγ1.2-Jγ2和Vγ2-Jγ1片段。相反，在突变小鼠中未检测到这种重组。在对照小鼠和突变小鼠中，TCR-α、β和δ基因座的重排情况相当。PCR分析表明，突变小鼠中所有Vγ基因的V-J重组均受到严重阻碍。在对照胸腺和突变胸腺中均能等量检测到RAG-1、RAG-2、Ku-80和末端脱氧核苷酸转移酶（TdT）基因的mRNA，这表明常见重组机制的表达未受影响。这些数据表明，在IL-7R缺陷型小鼠中，TCRγ基因的V-J重组被特异性阻断，并提示存在对TCRγ基因重排的高度特异性调控。
