Mouse germline transcript of TCR alpha joining region and temporal expression in ontogeny

The genetic element 'T early alpha' (TEA) in humans is located immediately 5' to the most upstream joining segment (phi J alpha) of the TCR alpha chain locus. The TEA transcript is present early in thymocyte ontogeny and the TEA-associated deletion of the TCR delta locus (delta Rec/phi J alpha rearrangement) precedes V alpha/J alpha rearrangement. We detected a 1.8 kb transcript homologous to human TEA that is spliced to C alpha in mouse thymic lymphomas showing concomitant rearrangement and expression of TCR gamma, delta, beta, and alpha. The TEA expression was highest in day 17 fetal thymocytes and declined thereafter. This expression parallels the TCR delta gene expression which is preceded by TCR gamma expression, and followed by the expression of TCR beta and alpha genes.