Bob1 (OCA-B/OBF-1) Differential Transactivation of the B Cell-SpecificB29(Igβ) andmb-1(Igα) Promoters
- 1 April 2002
- journal article
- Published by The American Association of Immunologists in The Journal of Immunology
- Vol. 168 (7), 3369-3375
- https://doi.org/10.4049/jimmunol.168.7.3369
Abstract
The B29 (Igbeta) and mb-1 (Igalpha) gene products are B cell-specific essential components of the B cell receptor that are coexpressed at all stages of B cell differentiation, with the exception of plasma cells, which lack mb-1 expression. Transcription of both genes is governed by a similar cassette of interactive transcription factor-binding elements, including octamer motifs, in TATA-less promoters. In this study, we show the B cell-specific B29 gene promoter is transactivated in B and non-B cells by cotransfection with the B cell-specific octamer cofactor gene, Bob1 (OCA-B/OBF-1). The expression of Bob1 is also sufficient to override the silencing effects of the B29 silencer. This indicates that Bob1 plays a critical role in B cell-specific B29 promoter expression. In contrast, coexpression of Bob1 had no effect on mb-1 promoter activity. Bob1 transactivation only occurs with select octamer sequences that have an adenosine at position 5 (ATGCAAAT). The B29 promoter conforms to this consensus octamer motif, while the mb-1 promoter octamer motif does not. Octamer motif swapping between B29 and mb-1 promoters renders B29 unresponsive to Bob1 transactivation and makes mb-1 competent for Bob1 transactivation, thereby indicating that the B29 octamer motif is solely responsible for Bob1 interaction. Additionally, the mb-1 construct containing the B29 octamer motif is expressed in a plasmacytoma cell line, while the wild-type mb-1 promoter is not. Bob1 transactivation of B29 and the lack of this transactivation of mb-1 account for the differential expression of B29 and mb-1 in terminally differentiated plasma cells.Keywords
This publication has 34 references indexed in Scilit:
- B lymphocytes are impaired in mice lacking the transcriptional co‐activator Bob1/OCA‐B/OBF1European Journal of Immunology, 1996
- The B-cell-specific transcription coactivator OCA-B/OBF-1/Bob-1 is essential for normal production of immunoglobulin isotypesNature, 1996
- B-cell-specif ic coactivator OBF-1/OCA-B/Bob1 required for immune response and germinal centre formationNature, 1996
- Sequence-specific DNA binding of the B-cell-specific coactivator OCA-B.Published by Cold Spring Harbor Laboratory ,1996
- Receptor Tails Unlock Developmental Checkpoints for B LymphocytesScience, 1996
- Functional Characterization of the Murine Homolog of the B cell-specific Coactivator BOB.1/OBF.1Online Journal of Public Health Informatics, 1995
- Failure of B-cell differentiation in mice lacking the transcription factor EBFNature, 1995
- Class II transactivator (CIITA) is sufficient for the inducible expression of major histocompatibility complex class II genes.The Journal of Experimental Medicine, 1994
- Cloning and functional characterization of early B-cell factor, a regulator of lymphocyte-specific gene expression.Journal of Bone and Joint Surgery, 1993
- Cell-type specificity of iminunoglobulin gene expression is regulated by at least three DNA sequence elementsCell, 1985