title: Apc bridges Wnt/β-catenin and BMP signaling during osteoblast differentiation of KS483 cells.
abstract: The canonical Wnt signaling pathway influences the differentiation of mesenchymal cell lineages in a quantitative and qualitative fashion depending on the dose of β-catenin signaling. Adenomatous polyposis coli (Apc) is the critical intracellular regulator of β-catenin turnover. To better understand the molecular mechanisms underlying the role of Apc in regulating the differentiation capacity of skeletal progenitor cells, we have knocked down Apc in the murine mesenchymal stem cell-like KS483 cells by stable expression of Apc-specific small interfering RNA. In routine culture, KSFrt-Apc(si) cells displayed a mesenchymal-like spindle shape morphology, exhibited markedly decreased proliferation and increased apoptosis. Apc knockdown resulted in upregulation of the Wnt/β-catenin and the BMP/Smad signaling pathways, but osteogenic differentiation was completely inhibited. This effect could be rescued by adding high concentrations of BMP-7 to the differentiation medium. Furthermore, KSFrt-Apc(si) cells showed no potential to differentiate into chondrocytes or adipocytes. These results demonstrate that Apc is essential for the proliferation, survival and differentiation of KS483 cells. Apc knockdown blocks the osteogenic differentiation of skeletal progenitor cells, a process that can be overruled by high BMP signaling.
authors.affiliation: Department of Pediatrics, Leiden University Medical Centre, Leiden, the Netherlands. R.L.Miclea@lumc.nl
authors.forename: Razvan L
authors.initials: RL
authors.lastname: Miclea
authors.forename: Geertje
authors.initials: G
authors.lastname: van der Horst
authors.forename: Els C
authors.initials: EC
authors.lastname: Robanus-Maandag
authors.forename: Clemens W G M
authors.initials: CW
authors.lastname: Löwik
authors.forename: Wilma
authors.initials: W
authors.lastname: Oostdijk
authors.forename: Jan M
authors.initials: JM
authors.lastname: Wit
authors.forename: Marcel
authors.initials: M
authors.lastname: Karperien
mesh_terms: D025601:Adenomatous Polyposis Coli Protein / Q000235:genetics / Q000378:metabolism*; D017667:Adipocytes / Q000166:cytology / Q000378:metabolism; D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D055419:Bone Morphogenetic Protein 7 / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D059630:Mesenchymal Stem Cells / Q000378:metabolism*; D051379:Mice; D010006:Osteoblasts / Q000166:cytology* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D051153:Wnt Proteins / Q000235:genetics / Q000378:metabolism*; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism*
chemical_list: D025601:Adenomatous Polyposis Coli Protein; D055419:Bone Morphogenetic Protein 7; D012333:RNA, Messenger; D051153:Wnt Proteins; D051176:beta Catenin