The BOB.1 / OBF.1 co‐activator is essential for octamer‐dependent transcription in B cells

The BOB.1 / OBF.1 / OCA‐B protein (henceforth designated as BOB.1 / OBF.1) is a B cell‐specific co‐activator of the Oct1 and Oct2 transcription factors. It is involved in mediating the transcriptional activity of these proteins. Surprisingly, animals deficient for BOB.1 / OBF.1 showed normal express...

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Bibliographic Details
Published in:European journal of immunology 2000-02, Vol.30 (2), p.458-469
Main Authors: Laumen, Helmut, Nielsen, Peter J., Wirth, Thomas
Format: Article
Language:English
Subjects:
Animals
B cell‐specific gene expression
B-Lymphocytes - physiology
BOB.1 / OBF.1 co‐activator
Conditional gene regulation
Gene Expression Regulation - immunology
Lymphocyte Activation - immunology
Mice
Mice, Knockout
Oct1 / Oct2 transcription factor
Octamer‐dependent transcription
Trans-Activators - physiology
Transcription, Genetic - immunology
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Summary:The BOB.1 / OBF.1 / OCA‐B protein (henceforth designated as BOB.1 / OBF.1) is a B cell‐specific co‐activator of the Oct1 and Oct2 transcription factors. It is involved in mediating the transcriptional activity of these proteins. Surprisingly, animals deficient for BOB.1 / OBF.1 showed normal expression of genes that contain an octamer motif in their regulatory regions. Here we have addressed the role of BOB.1 / OBF.1 for octamer‐dependent transcription. We show that promoters exclusively dependent on functional octamer motifs are completely inactive in BOB.1 / OBF.1‐deficient B cells. The lack of activity is a direct consequence of lack of the co‐activator. To show this, a hormone‐regulated conditional allele of BOB.1 / OBF.1 was introduced into the BOB.1 / OBF.1‐deficient B cells. This resulted in the hormone‐dependent transcriptional activity of octamer‐dependent reporters in these cells. The BOB.1 / OBF.1 requirement for octamer promoter function was also observed when an authentic immunoglobulin κ‐promoter was assayed. BOB.1 / OBF.1 dependence could not be overcome by including the strong enhancer element from the immunoglobulin heavy chain gene. Induction of pre‐B cells with lipopolysaccharide led to increased Oct2 levels but did not significantly increase octamer‐dependent transcription in BOB.1 / OBF.1‐deficient B cells. Thus, these results demonstrate that BOB.1 / OBF.1 itself is a non‐redundant protein in B cells and absolutely required for octamer‐dependent transcriptional activity.
ISSN:0014-2980
1521-4141
DOI:10.1002/1521-4141(200002)30:2<458::AID-IMMU458>3.0.CO;2-5