A developmental stage-specific promoter directs germline transcription of D beta J beta gene segments in precursor T lymphocytes.

The tissue- and stage-specific assembly of Ag receptor genes is regulated by transcriptional control elements positioned within Ig and TCR loci. To further understand the role of cis-acting elements in these regulatory mechanisms, we have characterized a transcriptional promoter that drives germline expression of TCR beta gene segments in vivo. The activity of this promoter, termed PD beta, is restricted to a highly conserved 400-bp region located directly upstream from D beta 1-coding sequences. Maximal PD beta activity requires a TATA element situated within the D beta 1 recombination signal sequences and consensus binding sites for the ubiquitous SP1 and the T cell-specific GATA-3 transcription factors. When linked to active enhancer elements, PD beta directs transcription in most cell types; however, the TCR beta enhancer (E beta) stimulates PD beta function specifically in precursor T lymphocytes. These findings suggest that PD beta/E beta interactions may contribute to differential regulation of regions within the TCR beta locus during thymocyte development.