Alternative isoforms of KDM2A and KDM2B lysine demethylases negatively regulate canonical Wnt signaling

A precisely balanced activity of canonical Wnt signaling is essential for a number of biological processes and its perturbation leads to developmental defects or diseases. Here, we demonstrate here that alternative isoforms of the KDM2A and KDM2B lysine demethylases have the ability to negatively regulate canonical Wnt signaling. These KDM2A and KDM2B isoforms (KDM2A-SF and KDM2B-SF) lack the N-terminal demethylase domain, but they are able to bind to activated promoters in order to repress them. We have observed that KDM2A-SF and KDM2B-SF bind to and repress the promoters of AXIN2 and CYCLIN D1, two canonical Wnt signaling target genes. Moreover, KDM2A-SF and KDM2B-SF can repress a Wnt-responsive luciferase reporter. The transcriptional repression mediated by KDM2A-SF and KDM2B-SF, but also by KDM2A-LF, is dependent on their DNA binding domain, while the N-terminal demethylase domain is dispensable for this process. Surprisingly, KDM2B-LF is unable to repress both the endogenous promoters and the luciferase reporter. Finally, we show that both KDM2A-SF and KDM2B-SF are able to interact with TCF7L1, one of the transcriptional mediators of canonical Wnt signaling. KDM2A-SF and KDM2B-SF are thus likely to affect the transcription of the TCF7L1 target genes also through this interaction.