OBF-1, a novel B cell-specific coactivator that stimulates immunoglobulin promoter activity through association with octamer-binding proteins

• Published in: Cell 1995-02, Vol.80 (3), p.497-506
• Main Authors: Strubin, Michel, Newell, John W, Matthias, Patrick
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; amino acid sequence prediction; B-Lymphocytes; cDNA; Cell Line; Cloning, Molecular; DNA - metabolism; DNA-Binding Proteins - metabolism; gene expression; Gene Expression Regulation - physiology; Gene Library; Genes, Immunoglobulin - genetics; HeLa Cells; Host Cell Factor C1; Humans; immunoglobulins; lymphocytes B; man; Molecular Sequence Data; Oct-binding factor 1; Octamer Transcription Factor-1; Octamer Transcription Factor-2; octamer-binding protein; Organ Specificity; Promoter Regions, Genetic - genetics; RNA; RNA, Fungal - analysis; RNA, Messenger - analysis; Sequence Analysis, DNA; Trans-Activators - genetics; Trans-Activators - metabolism; transcription factors; Transcription Factors - metabolism; Transcriptional Activation - genetics; Yeasts - genetics
• ISSN: 0092-8674; 1097-4172
• DOI: 10.1016/0092-8674(95)90500-6

Recent biochemical and genetic studies indicate that in addition to the octamer-binding proteins Oct-1 and Oct-2, other B cell components are required for lymphoid-restricted, octamer site-mediated immunoglobulin gene promoter activity. Using a genetic screen in yeast, we have isolated B cell-derived cDNAs encoding Oct-binding factor 1 (OBF-1), a novel protein that specifically associates with Oct-1 and Oct-2. Biochemical studies demonstrate that OBF-1 has no intrinsic DNA-binding activity and recognizes the POU domains of Oct-1 and Oct-2, but not those of Oct-4 and Oct-6. The OBF-1 mRNA is expressed in a highly cell-specific manner, being most abundant in B cells and essentially absent in most of the other cells or tissues tested. Furthermore, expression of OBF-1 in HeLa cells selectively stimulates the activity of a natural immunoglobulin promoter in an octamer site-dependent manner. Thus, OBF-1 has all the properties expected for a B cell-specific transcriptional coactivator protein.