Characterization of the B lymphocyte-induced maturation protein-1 (Blimp-1) gene, mRNA isoforms end basal promoter

Blimp-1 is a transcriptional repressor that is both required and sufficient to trigger terminal differentiation of B lymphocytes and monocyte/macropha ges. Here we report the organization of the mouse Blimp-1 gene, an analysis of Blimp-1 homologs in different species, the characterization of Blimp-1 mRNA isoforms and initial studies on the transcription of Blimp-1, The muri ne Blimp-1 gene covers similar to 23 kb and contains eight exons, There are Blimp-1 homologs in species evolutionarily distant from mouse (Caenorhabdi tis elegans and Drosophila melanogaster) but no homolog was found in the un icellular yeast Saccharomyces cerevisiae, The three major Blimp-1 mRNA isof orms result from the use of different polyadenylation sites and do not enco de different proteins, Run-on transcription analyses were used to show that the developmentally regulated expression of Blimp-1 mRNA in B cells is det ermined by transcription initiation. Multiple Blimp-1 transcription initiat es sites were mapped near an initiator element and a region conferring basa l promoter activity has been identified.