The lymphoid-specific cofactor OBF-1 is essential for the expression of a VH promoter/HS1,2 enhancer-linked transgene in late B cell development

Mice deficient for the lymphoid-specific cofactor OBF-1 display reduced levels of IgG, IgA and IgE. To examine whether the lowered immunoglobulin expression is linked to reduced activity of IgH cis-regulatory elements, OBF-1−/− mice were crossed with mice expressing transgenes driven by a VH or β-globin promoter linked to the HS1,2 enhancer. Here we show that OBF-1 is essential for the induced expression of a VH promoter-linked transgene, in contrast to a β-globin promoter-dependent transgene, in LPS/IL-4 or CD40-stimulated splenic B cells. Furthermore, impaired transgene expression is observed in OBF-1−/− peritoneal B cells. This deficiency may be linked to OBF-1, as peritoneal cells from normal mice express OBF-1 protein constitutively. Our data link OBF-1 to IgH gene expression in late B lymphoid development.