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.
Keywords: CP; CP: Molecular Biology; Molecular Biology; Wnt signaling pathway; neddylation; stabilization; ubiquitylation; β-TrCP2; β-catenin.
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