Takeshita S, Toda M, Yamagishi H
Department of Biophysics, Faculty of Science, Kyoto University, Japan.
EMBO J. 1989 Nov;8(11):3261-70. doi: 10.1002/j.1460-2075.1989.tb08486.x.
We have cloned extrachromosomal circular DNAs containing T cell receptor (TCR) delta gene segments in adult mouse thymocytes and splenocytes. We find that the frequency of circular DNA clones carrying germline delta sequences is lower than that of J alpha probe-positive clones, possibly related to increasing 5' distance from the most upstream J alpha segment. This suggests that the TCR alpha/delta locus is successively rearranged from within and that the delta-containing excision products are progressively diluted out by the subsequent cell division which includes further alpha gene rearrangements. In addition, examination of delta gene excision products revealed newly identified V delta subfamilies, the reciprocal joining of two D delta elements, J delta 2 usage in thymocytes and novel sequences homologous to the human delta-gene deleting elements.
我们已在成年小鼠胸腺细胞和脾细胞中克隆出含有T细胞受体（TCR）δ基因片段的染色体外环状DNA。我们发现，携带种系δ序列的环状DNA克隆的频率低于Jα探针阳性克隆，这可能与距最上游Jα片段的5'距离增加有关。这表明TCRα/δ基因座是从内部依次重排的，并且含δ的切除产物通过随后的细胞分裂（包括进一步的α基因重排）而逐渐被稀释。此外，对δ基因切除产物的检测揭示了新鉴定的Vδ亚家族、两个Dδ元件的相互连接、胸腺细胞中Jδ2的使用以及与人δ基因缺失元件同源的新序列。
