TRANSCRIPTION FACTOR NF-KAPPA-B REGULATES INDUCIBLE OCT-2 GENE-EXPRESSION IN PRECURSOR B-LYMPHOCYTES

The POU transcription factors Oct-1 and Oct-2 regulate the activity of octamer-dependent promoters, including those that direct transcriptio n from rearranged immunoglobulin genes, Unlike Oct-1, which is constit utively expressed in many cell types, Oct-2 expression is restricted p rimarily to B lymphocytes and can be induced in precursor B cells by s timulation with bacterial Lipopolysaccharide (LPS), However, the preci se factors that mediate this induction mechanism remain unknown. In th e present study, we monitored Oct-2; expression in cells arrested for the activation of NF-kappa B, an LPS-responsive member of the Rel tran scription factor family. Despite stimulation with LPS, disruption of t he NF-kappa B signaling pathway in precursor B cells led to the loss o f inducible Oct-2 DNA binding activity in vitro and the suppression of Oct-2-directed transcription in vivo. This biochemical defect correla ted with a specific block to Oct-2 gene expression at the level of tra nscription, whereas the expression of Oct-1 was unaffected. The findin g that Oct-2 is under NF-kappa B control highlights an important cross -talk mechanism involving two distinct transcription factor families t hat regulate B lymphocyte function.