Characterization of the mouse Tcra-V22 gene subfamily

The mouse (Mus musculus) T cell receptor alpha (TRA) and delta (TRD) variable genes

'The Mouse (Mus musculus) T cell receptor alpha (TRA) and delta (TRD) variable genes' 'IMGT Locus in Focus' report provides the first complete list of the mouse TRAV and TRDV genes which span 1550 kb on chromosome 14 at 19.7 cM. The total number of TRAV genes per haploid genome is 98 belonging to 23 subgroups. This includes 10 TRAV/DV genes which belong to seven subgroups. The functional TRAV genomic repertoire comprises 72-82 TRAV (including 9-10 TRAV/DV) belonging to 19 subgroups. The total number of TRDV genes per haploid genome is 16 (including the 10 TRAV/DV) belonging to 12 subgroups. The functional TRDV genomic repertoire comprises 14-15 genes (5 TRDV and 9-10 TRAV/DV) belonging to 11-12 subgroups. The eight tables and three figures of this report are available at the IMGT Marie-Paule page of IMGT. The international ImMunoGeneTics information system (http://imgt.cines.fr) created by Marie-Paule Lefranc, Université Montpellier II, CNRS, France.

T cell receptor gene polymorphisms associated with anti-insulin, autoimmune T cells in diabetes-prone NOD mice

The great majority of insulin-specific T cell clones isolated from islets of NOD mice react with insulin peptide B-(9-23) (amino acids 9-23 of the insulin B chain). The T cell receptors of these clones contain diverse beta-chains but restricted alpha-chains. The dominant alpha-chain motif is a V alpha 13 segment (10 out of 13) combined to either a J alpha 45 or a J alpha 34 segment (eight out of 13). Furthermore, nine out of 10 of these V alpha 13 segments are a product of a novel NOD TCR V alpha gene which we have termed V alpha 13.3. Analysis of V alpha 13 transcripts from splenic cDNA libraries from the NOD, BALB/c and C57BL/6 mice revealed significant differences between strains. The NOD sequences contained both V alpha 13.1 and the novel V alpha 13.3. The BALB/c contained the previously reported V alpha 13.1 and V alpha 13.2, but not the V alpha 13.3 sequence identified in the NOD anti-insulin T cell clones. The C57BL/6 had V alpha 13.1 and V alpha 13.3 plus two additional novel sequences which we have termed V alpha 13.4 and V alpha 13.5. These V alpha 13 subfamily members differed by two to four amino acids in either the CDR1 region or adjoining the CDR2 region. The frequency of utilization of the different V alpha 13 subtypes varied dramatically between strains. In the NOD spleen, V alpha 13.3 was detected 79% of the time, compared to 21% for V alpha 13.1. In contrast, the C57BL/6 spleen contained only 7% of V alpha 13.3 sequences compared to the other subfamily members present (V alpha 13.1: 27%; V alpha 13.4: 56%; V alpha 13.5: 10%). MHC polymorphisms or other unknown selective pressures may contribute to these differences in V alpha 13 utilization. We hypothesize that the presence and frequent utilization of the V alpha 13.3 T cell receptor element is involved in targeting insulin B-(9-23) and may be related to diabetes susceptibility of NOD mice.