title: Establishment of fibrillin-deficient osteoprogenitor cell lines identifies molecular abnormalities associated with extracellular matrix perturbation of osteogenic differentiation.
abstract: Fibrillin-1 and fibrillin-2 are structural components of the extracellular matrix which are also involved in modulating local TGFβ and BMP bioavailability. Loss of fibrillin-1 or fibrillin-2 is associated with perturbed osteoblast maturation principally as the result of unbalanced TGFβ and BMP signaling. Here, we demonstrated that stable expression of small hairpin RNAs against fibrillin-1(Fbn1) or fibrillin-2 (Fbn2) transcripts in the clonal osteoprogenitor cell line Kusa-A1 led to the same phenotypic and molecular manifestations as germline Fbn1- or Fbn2-null mutations in primary calvarial osteoblast cultures. Proof-of-concept experiments are also presented showing that Fbn1- or Fbn2-silenced Kusa-A1 cell lines are suitable models to identify candidate determinants of osteogenesis which are under the control of extracellular microfibrils. Specific findings included: the inference of a potential role for fibrillin-1-mediated cell-matrix interactions in regulating Kusa-A1 proliferation; the possibility of fibrillin-2 involvement in modulating the activity of transcription factor Runx2 by restricting microRNA expression and/or processing; and the suggestion that fibrillin-1 and fibrillin-2 influence Notch signaling indirectly by differentially regulating BMP signaling. Collectively, the data reiterated the notion that fibrillin-1 and fibrillin-2 exert opposite effects on osteoblast differentiation through the discrete modulation of a broad network of interacting signaling molecules.
authors.affiliation: Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029, USA.
authors.forename: Silvia
authors.initials: S
authors.lastname: Smaldone
authors.forename: Luca
authors.initials: L
authors.lastname: Carta
authors.forename: Francesco
authors.initials: F
authors.lastname: Ramirez
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D002460:Cell Line; D005109:Extracellular Matrix / Q000378:metabolism*; D000071838:Fibrillin-1; D000071840:Fibrillin-2; D000071837:Fibrillins; D051379:Mice; D008840:Microfilament Proteins / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology* / Q000378:metabolism*; D015398:Signal Transduction; D014162:Transfection; D054392:Adipokines
chemical_list: D000071838:Fibrillin-1; D000071840:Fibrillin-2; D000071837:Fibrillins; D008840:Microfilament Proteins; C000605724:Fbn1 protein, mouse; D054392:Adipokines; C000605728:Fbn2 protein, mouse