Excision products of the T cell receptor gene support a progressive rearrangement model of the alpha/delta locus.
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.
Takeshita
S
S
Department of Biophysics, Faculty of Science, Kyoto University, Japan.
Toda
M
M
Yamagishi
H
H
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D003001:Cloning, Molecular; D004270:DNA, Circular / Q000235:genetics; D015329:Gene Rearrangement, T-Lymphocyte; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008957:Models, Genetic; D008969:Molecular Sequence Data; D011948:Receptors, Antigen, T-Cell / Q000235:genetics*; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid; D013154:Spleen / Q000378:metabolism; D013950:Thymus Gland / Q000378:metabolism
D004270:DNA, Circular; D011948:Receptors, Antigen, T-Cell