The OBF-1 gene locus confers B cell-specific transcription by restricting the ubiquitous activity of its promoter.
Transcription of the gene encoding the transcriptional coactivator Oct-binding factor 1 (OBF-1)/OCA-B/Bob.1 is largely restricted to B cells. During B cell development OBF-1 expression shows two peaks, one in immature B cells in the bone marrow and the other in germinal center B cells. Promoter analysis has identified a cAMP response element (CRE)-binding site present in the OBF-1 proximal promoter that is crucial for activity in B cells and for the induction of OBF-1 expression upon stimulation with CD40 ligand/IL-4. Here we address the question of how transcription of the OBF-1 gene is restricted to B cells. Surprisingly, in transient transfection assays the OBF-1 proximal promoter exhibited an equally strong activity in B and non-B cells. In contrast, upstream promoter regions displayed B cell-specific properties, partly overlapping with DNaseI hypersensitive sites identified in this study. In mice, expression of a neomycin resistance gene under the control of a Polyoma enhancer/TK promoter cassette was restricted to B cells when integrated into the OBF-1 locus, but was ubiquitous when integrated into two other loci, Oct-1 or the large subunit of RNA polymerase II.Therefore, lineage commitment of the OBF-1 gene is promoter independent and is achieved by regulating the entire locus in a B cell-specific manner.
D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism*; D002460:Cell Line; D002874:Chromosome Mapping; D003850:Deoxyribonuclease I / Q000494:pharmacology; D004742:Enhancer Elements, Genetic; D051379:Mice; D009154:Mutation; D009355:Neomycin / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D015534:Trans-Activators / Q000235:genetics*; D014158:Transcription, Genetic
C490424:Pou2af1 protein, mouse; D015534:Trans-Activators; D003850:Deoxyribonuclease I; D009355:Neomycin