TCR repertoire in early fetal mouse thymus.
We investigated the rearrangement and expression of TCR genes in mouse fetal thymus organ culture, a system that avoids subsequent entry of hematopoietic precursor cells. The first observable rearranged TCR gene was homogeneous V gamma 2-J gamma 2, detectable as early as fetal day 11 (d11) in the thymic primordia. The productive TCR was homogeneous V gamma 5-J gamma 1, first detectable in d13 thymocytes, followed by adult-type TCR gamma (V gamma 4 and V gamma 7). Sequence analysis of TCR revealed five types of V-J junctional sequences. In the very early stage, a homogeneous V-J junction is generated via a short homology sequence in the coding region (Type I), while a short homology sequence in the P-nucleotide rather than the coding region is used in the following stage (Type II). In the later embryonic stages, diverse V-J junctions are generated by well-known mechanisms, such as P-nucleotide (Type III), N-region insertion (Type IV) or trimming of the coding ends (Type V). These findings suggest that the generation of homogeneous TCR gamma (V gamma 2 and V gamma 5) in the early fetal stages is due to the intrinsic rearrangement mechanisms and is in stage specific manner.
Ohki-Hamazaki
H
H
Division of Molecular Immunology, School of Medicine, Chiba University, Japan.
Makino
Y
Y
Kanno
M
M
Koseki
H
H
Akasaka
T
T
Taniguchi
M
M
D000818:Animals; D001483:Base Sequence; D004270:DNA, Circular / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D005260:Female; D018507:Gene Expression Regulation, Developmental; D015329:Gene Rearrangement, T-Lymphocyte; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D009924:Organ Culture Techniques; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000235:genetics*; D016415:Sequence Alignment; D013047:Specific Pathogen-Free Organisms; D013950:Thymus Gland / Q000196:embryology / Q000276:immunology*
D004270:DNA, Circular; D018076:DNA, Complementary; D016692:Receptors, Antigen, T-Cell, gamma-delta