PCAF Acetylates β-Catenin and Improves Its Stability

Abstract

β-Catenin plays an important role in development and tumorigenesis. However, the effect of a key acetyltransferase p300/CBP-associated factor (PCAF) on β-catenin signaling is largely unknown. In this study, we found PCAF could increase the β-catenin transcriptional activity, induce its nuclear translocation, and up-regulate its protein level by inhibiting its ubiquitination and improving its stability. Further studies showed that PCAF directly binds to and acetylates β-catenin. The key ubiquitination sites Lys-19 and Lys-49 of β-catenin were shown as the critical residues for PCAF-induced acetylation and stabilization. Knockdown of PCAF in colon cancer cells markedly reduced the protein level, transcriptional activity, and acetylation level of β-catenin; promoted cell differentiation; inhibited cell migration; and repressed xenografted tumorigenesis and tumor growth in nude mice. All these data demonstrate that PCAF acetylates β-catenin and regulates its stability, and they raise the prospect that therapies targeting PCAF may be of clinical use in β-catenin–driven diseases, such as colon cancer.