title: TGF-β prevents phosphate-induced osteogenesis through inhibition of BMP and Wnt/β-catenin pathways.
abstract: BACKGROUND
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Instituto Maimónides para la Investigación Biomédica (IMIBIC). Hospital Reina Sofía. Universidad de Córdoba, Córdoba, Spain.
authors.forename: Fátima
authors.initials: F
authors.lastname: Guerrero
authors.affiliation: Instituto Maimónides para la Investigación Biomédica (IMIBIC). Hospital Reina Sofía. Universidad de Córdoba, Córdoba, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Herencia
authors.affiliation: Lipid and Atherosclerosis Unit. IMIBIC/Reina Sofía University Hospital/University of Córdoba, and CIBER Fisiopatología Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Córdoba, Spain.
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Almadén
authors.affiliation: Instituto Maimónides para la Investigación Biomédica (IMIBIC). Hospital Reina Sofía. Universidad de Córdoba, Córdoba, Spain.
authors.forename: Julio M
authors.initials: JM
authors.lastname: Martínez-Moreno
authors.affiliation: Instituto Maimónides para la Investigación Biomédica (IMIBIC). Hospital Reina Sofía. Universidad de Córdoba, Córdoba, Spain.
authors.forename: Addy
authors.initials: A
authors.lastname: Montes de Oca
authors.affiliation: Instituto Maimónides para la Investigación Biomédica (IMIBIC). Hospital Reina Sofía. Universidad de Córdoba, Córdoba, Spain.
authors.forename: María Encarnación
authors.initials: ME
authors.lastname: Rodriguez-Ortiz
authors.affiliation: Instituto Maimónides para la Investigación Biomédica (IMIBIC). Hospital Reina Sofía. Universidad de Córdoba, Córdoba, Spain.
authors.forename: Juan M
authors.initials: JM
authors.lastname: Diaz-Tocados
authors.affiliation: Departamento de Biología Ambiental y Salud Pública, Universidad de Huelva, Huelva, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Canalejo
authors.affiliation: Metabolic Disorders Department, Amgen, Inc. One Amgen Center Drive, Thousand Oaks, California, United States of America.
authors.forename: Mónica
authors.initials: M
authors.lastname: Florio
authors.affiliation: Department of Medicina y Cirugía Animal, Universidad de Cordoba, Cordoba, Spain.
authors.forename: Ignacio
authors.initials: I
authors.lastname: López
authors.affiliation: Metabolic Disorders Department, Amgen, Inc. One Amgen Center Drive, Thousand Oaks, California, United States of America.
authors.forename: William G
authors.initials: WG
authors.lastname: Richards
authors.affiliation: Instituto Maimónides para la Investigación Biomédica (IMIBIC). Hospital Reina Sofía. Universidad de Córdoba, Córdoba, Spain.
authors.forename: Mariano
authors.initials: M
authors.lastname: Rodriguez
authors.affiliation: Department of Medicina y Cirugía Animal, Universidad de Cordoba, Cordoba, Spain.
authors.forename: Escolástico
authors.initials: E
authors.lastname: Aguilera-Tejero
authors.affiliation: Instituto Maimónides para la Investigación Biomédica (IMIBIC). Hospital Reina Sofía. Universidad de Córdoba, Córdoba, Spain.
authors.forename: Juan R
authors.initials: JR
authors.lastname: Muñoz-Castañeda
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000235:genetics / Q000378:metabolism; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects; D002467:Cell Nucleus / Q000378:metabolism; D020869:Gene Expression Profiling; D016130:Immunophenotyping; D008297:Male; D059630:Mesenchymal Stem Cells / Q000187:drug effects / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D010012:Osteogenesis / Q000187:drug effects* / Q000502:physiology*; D010710:Phosphates / Q000378:metabolism; D021381:Protein Transport; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects*; D051900:Smad3 Protein / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D051153:Wnt Proteins / Q000378:metabolism*; D051176:beta Catenin / Q000378:metabolism*
chemical_list: D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D010710:Phosphates; D051900:Smad3 Protein; D016212:Transforming Growth Factor beta; D051153:Wnt Proteins; D051176:beta Catenin