Tissue specificity of the initiation of immunoglobulin kappa gene transcription.

The transient transcription of a rearranged mouse immunoglobulin kappa gene was studied in a monkey fibroblast cell line. The gene was inserted into an SV40 expression vector and the calcium phosphate coprecipitation method was used for transfection. The transcripts were correctly spliced; transcription, however, was initiated within the vector and not at the correct site 23-26 bp upstream of the gene, irrespective of the length of the upstream sequences (90, 160, 370, and 870 bp) in the plasmid constructs. In contrast, accurately initiated transcripts were observed when a plasmid containing the kappa gene with 870 bp of its upstream sequence was introduced into a lymphoid cell line; the plasmid was constructed from the pSV2-gpt vector and the electric impulse method was used for gene transfer in most experiments. Tissue-specific expression of kappa light chain genes in lymphoid cells is known to depend on the presence of an enhancer element in the J-C intron. The results reported in this paper suggest that the sequence elements pd and dc which are located upstream of the leader gene segment also act in a tissue-specific manner and that it is the initiation of transcription which is a tissue-specific event.