Bcr interferes with β-catenin–Tcf1 interaction

The β-catenin/Tcf complex is a downstream effector of the Wnt signalling pathway. It is a transcription complex, which activates gene expression and contributes to proliferation and tumor progression. Tcf1 in complex with β-catenin is able to activate β-catenin-dependent gene expression. We demonstrate that expressed Bcr is able to bind the transcription factor Tcf1 to disrupt the Tcf1/β-catenin complex. Phosphorylation of Bcr by the tyrosine kinase pp60src can lead to dissociation of the transcriptionally inactive Bcr/Tcf1 complex. Thus two independent mechanisms may regulate Tcf/β-catenin-mediated transcription via Bcr: binding to β-catenin as we have previously shown and to Tcf1 as shown here.