title: Bone morphogenetic protein signaling in articular chondrocyte differentiation.
abstract: Articular chondrocytes progressively undergo dedifferentiation into a spindle-shaped mesenchymal cellular phenotype in monolayers. Chondrocyte dedifferentiation is stimulated by retinoic acid. On the other hand, bone morphogenic proteins (BMPs) stimulate differentiation of chondrocytes. We examined the mechanism of effects of BMP in chondrocyte differentiation with use of a recombinant adenovirus vector system. Constitutively active forms of BMP type I receptors (BMPR-IA and BMPR-IB) and those of activin receptor-like kinase (ALK)-1 and ALK-2 maintained differentiation of chondrocytes in the presence of retinoic acid. The BMP receptor-regulated signaling substrates, Smad1/5, weakly induced chondrocyte differentiation; the effects of Smad1/5 were enhanced by BMP-7 treatment. Inhibitory Smad, Smad6, blocked increase of expression of chondrocyte markers by BMP-7 in a dose-dependent manner. SB202190, a p38 mitogen-activated protein kinase inhibitor, inhibited this effect of BMP-7; however, since SB202190 suppressed phosphorylation of Smad1/5, this may be due to blockade of BMP receptor activation. These results together strongly suggest that induction of chondrocyte differentiation by BMP-7 is regulated by Smad pathways.
authors.affiliation: Center for Tissue Regeneration and Repair and Department of Orthopedic Surgery, University of California-Davis, Medical Center, Sacramento, CA 95817, USA.
authors.forename: Ayako
authors.initials: A
authors.lastname: Nishihara
authors.forename: Makiko
authors.initials: M
authors.lastname: Fujii
authors.forename: T Kuber
authors.initials: TK
authors.lastname: Sampath
authors.forename: Kohei
authors.initials: K
authors.lastname: Miyazono
authors.forename: A Hari
authors.initials: AH
authors.lastname: Reddi
mesh_terms: D030201:Activin Receptors, Type I / Q000235:genetics / Q000378:metabolism; D030301:Activin Receptors, Type II; D000256:Adenoviridae / Q000235:genetics / Q000378:metabolism; D000818:Animals; D055419:Bone Morphogenetic Protein 7; D052005:Bone Morphogenetic Protein Receptors, Type I; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology*; D002358:Cartilage, Articular / Q000166:cytology / Q000378:metabolism*; D002417:Cattle; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D011506:Proteins; D011725:Pyridines / Q000494:pharmacology; D017978:Receptors, Growth Factor / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D051785:Smad Proteins; D051898:Smad1 Protein; D051902:Smad5 Protein; D051905:Smad6 Protein; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D016212:Transforming Growth Factor beta; D014212:Tretinoin / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007093:Imidazoles; D010750:Phosphoproteins; D011506:Proteins; D011725:Pyridines; D017978:Receptors, Growth Factor; D051785:Smad Proteins; D051898:Smad1 Protein; C497401:Smad1 protein, mouse; D051902:Smad5 Protein; C497798:Smad5 protein, mouse; D051905:Smad6 Protein; C497803:Smad6 protein, mouse; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D014212:Tretinoin; D017346:Protein Serine-Threonine Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D030201:Activin Receptors, Type I; D030301:Activin Receptors, Type II; C498931:Acvrl1 protein, mouse; C498212:Bmpr1a protein, mouse; C498215:Bmpr1b protein, mouse; D052005:Bone Morphogenetic Protein Receptors, Type I; C090942:4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)imidazole; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one