Post-transcriptional regulation of E2A proteins via lipopolysaccharide andCD40 signaling

The transcription factor E2A plays a crucial role in B cell development, th e control of immunoglobulin gene rearrangement and expression. Here we repo rt that in primary mouse B cells lipopolysaccharide (LPS) is able to induce the level of E2A protein by over 50-fold in 3 days of culture. In contrast , CD40 signaling is insufficient to cause an E2A increase and can in fact p revent the LPS-mediated induction of E2A. These results suggest that E2A in duction requires both proliferation and differentiation. We find that E2A p rotein induction is regulated post-transcriptionally since E2A mRNA is not induced by LPS. We have thus identified an important additional layer of re gulation affecting the activity of E2A transcription factors.