Neddylation is essential for β-catenin degradation in Wnt signaling pathway

β-Catenin is a central component in the Wnt signaling pathway; its degradation has been tightly connected to ubiquitylation, but it is rarely examined by loss-of-function assays. Here we observe that endogenous β-catenin is not stabilized upon ubiquitylation depletion by a ubiquitylation inhibitor, TAK-243. We demonstrate that N-terminal phosphorylated β-catenin is quickly and strongly stabilized by a specific neddylation inhibitor, MLN4924, in all examined cell types, and that β-catenin and TCF4 interaction is strongly enhanced by inhibition of neddylation but not ubiquitylation. We also confirm that the E3 ligase β-TrCP2, but not β-TrCP1, is associated with neddylation and destruction of β-catenin. GSK3β and adenomatous polyposis coli (APC) are not required for β-catenin neddylation but essential for its subsequent degradation. Our findings not only clarify the process of β-catenin modification and degradation in the Wnt signaling pathway but also highlight the importance of reassessing previously identified ubiquitylation substrates. [Display omitted] •Neddylation is essential for β-catenin degradation•β-TrCP2 is associated with neddylation and destruction of β-catenin•GSK3 and APC are not required for β-catenin neddylation•GSK3 and APC are essential for degradation of neddylated β-catenin Wang et al. report a central role of neddylation for β-catenin degradation in Wnt signaling. They also identify β-TrCP2 as a candidate E3 ligase for β-catenin neddylation and demonstrate that GSK3 and APC are not required for β-catenin neddylation but essential for the subsequent degradation.