title: The orphan nuclear estrogen receptor-related receptor-alpha regulates cartilage formation in vitro: implication of Sox9.
abstract: We report for the first time the expression of estrogen receptor-related receptor (ERR)-alpha in fetal and adult rat chondrocytes in growth plate and articular cartilage and the rat chondrogenic cell line C5.18 cells in vitro. ERRalpha mRNA and protein were expressed from proliferating chondrocyte to mature chondrocyte stages. We show that overexpressing ERRalpha in C5.18 cell cultures induces an increase in Sry-type high-mobility-group box transcription factor (Sox)-9 expression, a master gene in cartilage formation. In parallel, we report Sox9 promoter regulation by ERRalpha in C5.18 cells. To assess a functional role for ERRalpha in chondrogenesis, its expression was blocked by antisense oligonucleotides in C5.18 cell cultures, and this led to inhibition of cartilage formation associated with down-regulation of Sox9 and Indian hedgehog expression and maturation of proliferating chondrocytes into hypertrophic chondrocytes in vitro. Together these results implicate ERRalpha in the formation and maintenance of cartilage and also suggest that agonists and antagonists of ERRalpha may be useful as therapeutic agents in a wide variety of diseases affecting cartilage and joints.
authors.affiliation: Department of Molecular and Medical Genetics, Faculty of Medicine, University of Toronto, Room 6230, Medical Sciences Building, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8.
authors.forename: E
authors.initials: E
authors.lastname: Bonnelye
authors.forename: R A
authors.initials: RA
authors.lastname: Zirngibl
authors.forename: P
authors.initials: P
authors.lastname: Jurdic
authors.forename: J E
authors.initials: JE
authors.lastname: Aubin
mesh_terms: D000818:Animals; D002356:Cartilage / Q000196:embryology / Q000378:metabolism / Q000502:physiology*; D049109:Cell Proliferation; D002478:Cells, Cultured; D019902:Chondrocytes / Q000378:metabolism; D020219:Chondrogenesis / Q000502:physiology*; D005786:Gene Expression Regulation; D006609:High Mobility Group Proteins / Q000378:metabolism / Q000502:physiology*; D008954:Models, Biological; D051381:Rats; D011960:Receptors, Estrogen / Q000378:metabolism / Q000502:physiology*; D055758:SOX9 Transcription Factor; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D014162:Transfection; D000097983:ERRalpha Estrogen-Related Receptor
chemical_list: D006609:High Mobility Group Proteins; D011960:Receptors, Estrogen; D055758:SOX9 Transcription Factor; D014157:Transcription Factors; D000097983:ERRalpha Estrogen-Related Receptor