Year-end Sale % OFF 
Abstract
Axin, a negative regulator of the Wnt signaling pathway, forms a complex with glycogen synthase kinase-3beta (GSK-3beta), beta-catenin, adenomatous polyposis coli (APC) gene product, and Dvl, and it regulates GSK-3beta-dependent phosphorylation in the complex and the stability of beta-catenin. Using yeast two-hybrid screening, we found that regulatory subunits of protein phosphatase 2A, PR61beta and -gamma, interact with Axin. PR61beta or -gamma formed a complex with Axin in intact cells, and their interaction was direct. The binding site of PR61beta on Axin was different from those of GSK-3beta, beta-catenin, APC, and Dvl. Although PR61beta did not affect the stability of beta-catenin, it inhibited Dvl- and beta-catenin-dependent T cell factor activation in mammalian cells. Moreover, it suppressed beta-catenin-induced axis formation and expression of siamois, a Wnt target gene, in Xenopus embryos, suggesting that PR61beta acts either at the level of beta-catenin or downstream of it. Taken together with the previous observations that PR61 interacts with APC and functions upstream of beta-catenin, these results demonstrate that PR61 regulates the Wnt signaling pathway at various steps.
Highlights
Wnt proteins constitute a large family of cysteine-rich secreted ligands that control development in organisms ranging from nematode worms to mammals [1]
Taken together with the previous observations that PR61 interacts with adenomatous polyposis coli (APC) and functions upstream of -catenin, these results demonstrate that PR61 regulates the Wnt signaling pathway at various steps
Because PR61 is a subunit of PP2A [41, 42], PP2A(CA) consisting of C and A subunits binds to Axin [16], and PR61 binds to Axin, we examined whether the trimer of PP2A associates with Axin
Summary
Wnt proteins constitute a large family of cysteine-rich secreted ligands that control development in organisms ranging from nematode worms to mammals [1]. Detection of Phosphorylated Axin by Antibody—To observe the phosphorylation state of Axin in intact cells, the lysates of COS, L, and 293 cells expressing wild-type Myc-rAxin, Myc-rAxinSA, or MycrAxin⌬GSK-3 with or without HA-PR61 or Flag-PP2A(C) were probed with the anti-P322, anti-P326, or anti-P330 antibody. These results indicate that Axin forms a complex with PR61 in intact cells and that the N-terminal region of Axin (1–529 amino acids) containing the RGS (regulators of the G protein signaling) domain and the GSK-3- and -catenin-binding sites is necessary for the interaction with PR61, but none of these individual sites is sufficient.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
