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XB-ART-2874
J Cell Biol. October 25, 2004; 167 (2): 339-49.

Distinct molecular forms of beta-catenin are targeted to adhesive or transcriptional complexes.

Gottardi CJ , Gumbiner BM .


Abstract
Beta-catenin plays essential roles in both cell-cell adhesion and Wnt signal transduction, but what precisely controls beta-catenin targeting to cadherin adhesive complexes, or T-cell factor (TCF)-transcriptional complexes is less well understood. We show that during Wnt signaling, a form of beta-catenin is generated that binds TCF but not the cadherin cytoplasmic domain. The Wnt-stimulated, TCF-selective form is monomeric and is regulated by the COOH terminus of beta-catenin, which selectively competes cadherin binding through an intramolecular fold-back mechanism. Phosphorylation of the cadherin reverses the TCF binding selectivity, suggesting another potential layer of regulation. In contrast, the main cadherin-binding form of beta-catenin is a beta-catenin-alpha-catenin dimer, indicating that there is a distinct molecular form of beta-catenin that can interact with both the cadherin and alpha-catenin. We propose that participation of beta-catenin in adhesion or Wnt signaling is dictated by the regulation of distinct molecular forms of beta-catenin with different binding properties, rather than simple competition between cadherins and TCFs for a single constitutive form. This model explains how cells can control whether beta-catenin is used independently in cell adhesion and nuclear signaling, or competitively so that the two processes are coordinated and interrelated.

PubMed ID: 15492040
PMC ID: PMC2172558
Article link: J Cell Biol.
Grant support: R37 GM374432 NIGMS NIH HHS

Genes referenced: cad cald1 cat.1 cdh1 csnk1a1 csnk2b ctnnbip1 myc s100a1 tbx2 wnt1 wnt3a

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