Ontogeny of TCR V beta 1 expression revealed novel invariant alternative transcripts.
Analysis of TCR-beta gene recombination and expression was performed by quantitative PCR amplification technique throughout chicken embryogenesis and development. Our data demonstrated that TCR V beta 1 promoters were turned on by day 10 of embryogenesis, 2 days before detection of TCR-beta gene recombination. The V to D recombination step was first detected by day 11 of embryogenesis whereas DJ and V(D)J rearranged genes were detected 1 day later, on day 12 of embryogenesis. Thus, transcription of unrearranged TCR-beta genes in chickens precedes the expression of V(D)J recombinase activity as in mammals. In contrast, although TCR-beta rearrangement starts with the D to J recombination step in mammals, it can start either by the VD or the DJ step in chickens. Furthermore, reverse transcriptase-PCR amplification of TCR-beta transcripts revealed the presence of two kinds of alternative transcripts. These novel alternatively spliced products appeared in thymocytes from embryonic thymus during colonization periods and were absent in transformed T cell lines. Splicing sites are located in the middle of V beta 1 segments and lead to delta V beta 1-C beta and delta V beta 1-D beta-J beta-C beta transcripts. delta V beta 1-C beta transcripts might lead to synthesis of invariant truncated TCR beta-chains containing the aminoterminal portion of the V beta 1 region followed by the C beta region. Because this type of splicing can be generated by using all known V beta 1 members, these invariant forms could play a role in thymocyte development.
Dunon
D
D
Laboratory of Experimental Biology, URA-CNRS 1135, Pierre and Marie Curie University, Paris, France.
Schwager
J
J
Dangy
J P
JP
Imhof
B A
BA
D017398:Alternative Splicing / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002642:Chick Embryo; D002645:Chickens; D003001:Cloning, Molecular; D015333:Gene Rearrangement, beta-Chain T-Cell Antigen Receptor / Q000235:genetics; D015698:Genomic Library; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000096:biosynthesis / Q000235:genetics*; D013950:Thymus Gland / Q000196:embryology / Q000254:growth & development; D014158:Transcription, Genetic / Q000235:genetics*
D016693:Receptors, Antigen, T-Cell, alpha-beta