RelA suppresses the Wnt/β-catenin pathway without exerting trans-acting transcriptional ability

Several cellular signaling systems exhibit cross talk. Cross talk seems to play an important role in modifying signal effects. In vertebrates, the nuclear factor K B (NF-KB) signaling pathway plays important roles in immune response, inflammation and apoptosis. Meanwhile, the Wnt/β-catenin signaling pathway is involved in oncogenesis and development. We show here that RelA, a component of NF-KB, specifically suppressed β-catenin/Tcf-dependent transcription. This suppression did not depend on the trans-acting transcriptional ability of RelA. Furthermore, RelA neither affected the nuclear import of β-catenin nor the DNA binding ability of the β-catenin/Tcf complex, suggesting that NF-KB modifies this signaling pathway after the binding of the β-catenin/Tcf complex with target DNA.