Apc bridges Wnt/β-catenin and BMP signaling during osteoblast differentiation of KS483 cells

• Published in: Experimental cell research Vol. 317; no. 10; pp. 1411 - 1421
• Main Authors: Miclea, Razvan L., van der Horst, Geertje, Robanus-Maandag, Els C., Löwik, Clemens W.G.M., Oostdijk, Wilma, Wit, Jan M., Karperien, Marcel
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 10.06.2011
• Subjects: Adenomatous Polyposis Coli Protein - genetics; Adenomatous Polyposis Coli Protein - metabolism; Adipocytes - cytology; Adipocytes - metabolism; Animals; Apc; Apoptosis; beta Catenin - genetics; beta Catenin - metabolism; Blotting, Western; Bone Morphogenetic Protein 7 - genetics; Bone Morphogenetic Protein 7 - metabolism; Cell Differentiation; Cell Proliferation; Cells, Cultured; Chondrocytes - cytology; Chondrocytes - metabolism; Differentiation; Fluorescent Antibody Technique; Mesenchymal Stromal Cells - metabolism; Mice; Osteoblast; Osteoblasts - cytology; Osteoblasts - metabolism; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - genetics; Signal Transduction; Wnt; Wnt Proteins - genetics; Wnt Proteins - metabolism; β-Catenin; Osteoblast; β-Catenin; Wnt; Differentiation; Apc
• ISSN: 0014-4827; 1090-2422
• DOI: 10.1016/j.yexcr.2011.03.007

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.