TGF-β prevents phosphate-induced osteogenesis through inhibition of BMP and Wnt/β-catenin pathways

• Published in: PloS one 2014-02, Vol.9 (2), p.e89179-e89179
• Main Authors: Guerrero, Fátima, Herencia, Carmen, Almadén, Yolanda, Martínez-Moreno, Julio M, Montes de Oca, Addy, Rodriguez-Ortiz, María Encarnación, Diaz-Tocados, Juan M, Canalejo, Antonio, Florio, Mónica, López, Ignacio, Richards, William G, Rodriguez, Mariano, Aguilera-Tejero, Escolástico, Muñoz-Castañeda, Juan R
• Format: Article
• Language: English
• Subjects: Actin; Activation; Alkaline phosphatase; Animals; Atherosclerosis; beta Catenin - metabolism; Biocompatibility; Biology; Bone morphogenetic protein 2; Bone Morphogenetic Protein 2 - genetics; Bone Morphogenetic Protein 2 - metabolism; Bone Morphogenetic Proteins - metabolism; Calcification; Calcium; Calcium phosphates; Cell Differentiation - drug effects; Cell Nucleus - metabolism; Deposition; Differentiation; Dkk1 protein; Gene expression; Gene Expression Profiling; Genetic transformation; Growth factors; Immunophenotyping; Inhibition; Kinases; Lithium; Lithium chloride; Low density lipoprotein receptors; Male; Medicine; Mesenchymal stem cells; Mesenchymal Stromal Cells - drug effects; Mesenchymal Stromal Cells - metabolism; Mesenchyme; Metabolic disorders; Muscle, Smooth, Vascular - cytology; Muscle, Smooth, Vascular - metabolism; Muscles; Myocytes, Smooth Muscle - cytology; Myocytes, Smooth Muscle - drug effects; Myocytes, Smooth Muscle - metabolism; Myosin; Nuclear transport; Osteogenesis; Osteogenesis - drug effects; Osteogenesis - physiology; Pathways; Phosphate; Phosphates; Phosphates - metabolism; Protein Transport; Proteins; Rats; Rodents; Signal transduction; Signal Transduction - drug effects; Signaling; Smad protein; Smad3 protein; Smad3 Protein - metabolism; Smooth muscle; Stem cells; Transcription factors; Transformation; Transforming Growth Factor beta - pharmacology; Transforming growth factor-a; Transforming growth factor-b; Translocation; Wnt protein; Wnt Proteins - metabolism; β-Catenin
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0089179

Transforming growth factor-β (TGF-β) is a key cytokine during differentiation of mesenchymal stem cells (MSC) into vascular smooth muscle cells (VSMC). High phosphate induces a phenotypic transformation of vascular smooth muscle cells (VSMC) into osteogenic-like cells. This study was aimed to evaluate signaling pathways involved during VSMC differentiation of MSC in presence or not of high phosphate. Our results showed that TGF-β induced nuclear translocation of Smad3 as well as the expression of vascular smooth muscle markers, such as smooth muscle alpha actin, SM22α, myocardin, and smooth muscle-myosin heavy chain. The addition of high phosphate to MSC promoted nuclear translocation of Smad1/5/8 and the activation of canonical Wnt/β-catenin in addition to an increase in BMP-2 expression, calcium deposition and alkaline phosphatase activity. The administration of TGF-β to MSC treated with high phosphate abolished all these effects by inhibiting canonical Wnt, BMP and TGF-β pathways. A similar outcome was observed in high phosphate-treated cells after the inhibition of canonical Wnt signaling with Dkk-1. Conversely, addition of both Wnt/β-catenin activators CHIR98014 and lithium chloride enhanced the effect of high phosphate on BMP-2, calcium deposition and alkaline phosphatase activity. Full VSMC differentiation induced by TGF-β may not be achieved when extracellular phosphate levels are high. Moreover, TGF-β prevents high phosphate-induced osteogenesis by decreasing the nuclear translocation of Smad 1/5/8 and avoiding the activation of Wnt/β-catenin pathway.