title: Reconstituting regulation of the canonical Wnt pathway by engineering a minimal β-catenin destruction machine.
abstract: Negatively regulating key signaling pathways is critical to development and altered in cancer. Wnt signaling is kept off by the destruction complex, which is assembled around the tumor suppressors APC and Axin and targets β-catenin for destruction. Axin and APC are large proteins with many domains and motifs that bind other partners. We hypothesized that if we identified the essential regions required for APC:Axin cooperative function and used these data to design a minimal β-catenin-destruction machine, we would gain new insights into the core mechanisms of destruction complex function. We identified five key domains/motifs in APC or Axin that are essential for their function in reconstituting Wnt regulation. Strikingly, however, certain APC and Axin mutants that are nonfunctional on their own can complement one another in reducing β-catenin, revealing that the APC:Axin complex is a highly robust machine. We used these insights to design a minimal β-catenin-destruction machine, revealing that a minimized chimeric protein covalently linking the five essential regions of APC and Axin reconstitutes destruction complex internal structure, size, and dynamics, restoring efficient β-catenin destruction in colorectal tumor cells. On the basis of our data, we propose a new model of the mechanistic function of the destruction complex as an integrated machine.
authors.affiliation: Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.
authors.forename: Mira I
authors.initials: MI
authors.lastname: Pronobis
authors.affiliation: Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.
authors.forename: Natalie
authors.initials: N
authors.lastname: Deuitch
authors.affiliation: Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.
authors.forename: Vinya
authors.initials: V
authors.lastname: Posham
authors.affiliation: Cellular Dynamics Analysis Unit, RIKEN Center for Life Science Technologies, Kobe 650-0047, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Mimori-Kiyosue
authors.affiliation: Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 peifer@unc.edu.|Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.|Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.
authors.forename: Mark
authors.initials: M
authors.lastname: Peifer
mesh_terms: D025601:Adenomatous Polyposis Coli Protein / Q000378:metabolism; D000818:Animals; D060466:Axin Protein / Q000378:metabolism* / Q000502:physiology; D045744:Cell Line, Tumor; D004330:Drosophila / Q000378:metabolism; D006801:Humans; D010766:Phosphorylation; D000072417:Protein Domains; D012097:Repressor Proteins / Q000378:metabolism; D051153:Wnt Proteins / Q000378:metabolism; D060449:Wnt Signaling Pathway / Q000502:physiology*; D051176:beta Catenin / Q000378:metabolism* / Q000502:physiology
chemical_list: D025601:Adenomatous Polyposis Coli Protein; D060466:Axin Protein; D012097:Repressor Proteins; D051153:Wnt Proteins; D051176:beta Catenin