title: An essential octamer motif in the mb-1 (Igalpha) promoter.
abstract: The mb-1 (Igalpha) gene is B cell-specific and expressed throughout B cell maturation. In combination with B29 (Igbeta) and surface immunoglobulin mb-1 comprises the B cell receptor complex (BCR). The murine mb-1 promoter has been characterized to depend on the trans-acting transcription factors; Sp1, ets, lkaros, and EBF for full promoter activity. These trans-acting factors are also involved in the regulation of mb-1's closely related heterodimeric partner, B29. However, octamer transcription factors 1 and 2 (Oct-1 and Oct-2) are also necessary for full B29 promoter activity while they are not known to be required for mb-1 promoter activity. Here, we show that the octamer transcription factors bind a degenerate octamer consensus sequence within the mb-1 promoter. Like B29, the mb-1 octamer-binding, motif interacted with both ubiquitously expressed Oct-1 and the B cell-specific Oct-2 transcription factors. Furthermore, the interaction of Oct-1 and Oct-2 contributed to the regulation of the mb-1 promoter as site-directed mutations within the octamer motif substantially reduced its activity. These data confirm that octamer factor interactions and function contribute to the full transcriptional activity of the mb-1 promoter.
authors.affiliation: Department of Microbiology and Immunology and The Molecular Biology Institute, School of Medicine, University of California, Los Angeles 90095, USA.
authors.forename: C S
authors.initials: CS
authors.lastname: Malone
authors.forename: L
authors.initials: L
authors.lastname: Patrone
authors.forename: R
authors.initials: R
authors.lastname: Wall
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000235:genetics*; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D051925:CD79 Antigens; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D051863:Host Cell Factor C1; D066298:In Vitro Techniques; D051379:Mice; D016297:Mutagenesis, Site-Directed; D050811:Octamer Transcription Factor-1; D050813:Octamer Transcription Factor-2; D015345:Oligonucleotide Probes / Q000235:genetics; D011401:Promoter Regions, Genetic; D011947:Receptors, Antigen, B-Cell / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D015703:Antigens, CD; D051925:CD79 Antigens; C497882:Cd79a protein, mouse; D004268:DNA-Binding Proteins; C497693:Hcfc1 protein, mouse; D051863:Host Cell Factor C1; D050811:Octamer Transcription Factor-1; D050813:Octamer Transcription Factor-2; D015345:Oligonucleotide Probes; C494166:Pou2f1 protein, mouse; C489206:Pou2f2 protein, mouse; D011947:Receptors, Antigen, B-Cell; D014157:Transcription Factors; D004247:DNA