Kdm2a/b Lysine Demethylases Regulate Canonical Wnt Signaling by Modulating the Stability of Nuclear β-Catenin

• Protein lysine demethylases Kdm2a/b inhibit Wnt/β-catenin signaling
• Kdm2a/b mediates the degradation of non-phosphorylated β-catenin within the nucleus
• Degradation of nuclear β-catenin depends on Kdm2a/b-induced demethylation
• Kdm2a/b regulate Xenopus body axis patterning via modulating nuclear β-catenin

SummaryIn the absence of Wnt activation, cytosolic β-catenin is degraded through GSK3/CK1-mediated phosphorylation at the N terminus. Here, we show that, upon Wnt activation, the stability of nuclear β-catenin is regulated via methylation/demethylation. The protein lysine demethylases Kdm2a and Kdm2b regulate the turnover of non-phosphorylated β-catenin specifically within the nucleus via direct interaction with the fourth and fifth armadillo repeats. The lysine residues within this region are required for the methylation of non-phosphorylated β-catenin, which is demethylated by Kdm2a/b and subsequently ubiquitylated. During Xenopus embryogenesis, kdm2a/b genes are transcribed during early embryogenesis and are required for the specification of the body axis. Kdm2a/b knockdown in Xenopus embryos leads to increases in non-phosphorylated and methylated β-catenin, concurrent with the upregulation of β-catenin target genes. This mechanism is required for controlling the output of the Wnt/β-catenin signaling pathway to maintain normal cellular functions.

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