title: Transcriptional coactivator PGC-1alpha regulates chondrogenesis via association with Sox9.
abstract: Chondrogenesis is a multistep pathway in which multipotential mesenchymal stem cells (MSC) differentiate into chondrocytes. The transcription factor Sox9 (SRY-related high mobility group-Box gene 9) regulates chondrocyte differentiation and cartilage-specific expression of genes, such as Col2a1 (collagen type II alpha1). However, Sox9 expression is detected not only in chondrogenic tissue but also in nonchondrogenic tissues, suggesting the existence of a molecular partner(s) required for Sox9 to control chondrogenesis and chondrogenic gene expression. Here, we report identification of peroxisome proliferator-activated receptor gamma co-activator 1alpha (PGC-1alpha) as a coactivator for Sox9 during chondrogenesis. Expression of PGC-1alpha is induced at chondrogenesis sites during mouse embryonic limb development and during chondrogenesis in human MSC cultures. PGC-1alpha directly interacts with Sox9 and promotes Sox9-dependent transcriptional activity, suggesting that PGC-1alpha acts as a transcriptional coactivator for Sox9. Consistent with this finding, PGC-1alpha disruption in MSC by small interfering RNA inhibits Col2a1 expression during chondrogenesis. Furthermore, overexpression of both PGC-1alpha and Sox9 induced expression of chondrogenic genes, including Col2a1, followed by chondrogenesis in the MSC and developing chick limb. Together, our results suggest a transcriptional mechanism for chondrogenesis that is coordinated by PGC-1alpha.
authors.affiliation: Department of Molecular and Experimental Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Kawakami
authors.forename: Masanao
authors.initials: M
authors.lastname: Tsuda
authors.forename: Shigeru
authors.initials: S
authors.lastname: Takahashi
authors.forename: Noboru
authors.initials: N
authors.lastname: Taniguchi
authors.forename: Concepción Rodríguez
authors.initials: CR
authors.lastname: Esteban
authors.forename: Michihisa
authors.initials: M
authors.lastname: Zemmyo
authors.forename: Takayuki
authors.initials: T
authors.lastname: Furumatsu
authors.forename: Martin
authors.initials: M
authors.lastname: Lotz
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Izpisúa Belmonte
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Asahara
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002642:Chick Embryo; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism; D020219:Chondrogenesis / Q000235:genetics* / Q000502:physiology*; D024043:Collagen Type II / Q000235:genetics; D004742:Enhancer Elements, Genetic; D018507:Gene Expression Regulation, Developmental; D006609:High Mobility Group Proteins / Q000235:genetics* / Q000502:physiology*; D006801:Humans; D017403:In Situ Hybridization; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism; D051379:Mice; D039902:Multipotent Stem Cells / Q000166:cytology / Q000378:metabolism; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D034741:RNA, Small Interfering / Q000235:genetics; D055758:SOX9 Transcription Factor; D015534:Trans-Activators / Q000235:genetics* / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics* / Q000502:physiology*; D014162:Transfection
chemical_list: C499177:COL2A1 protein, human; C447413:Col2a1 protein, mouse; D024043:Collagen Type II; D006609:High Mobility Group Proteins; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C485290:Ppargc1a protein, mouse; D034741:RNA, Small Interfering; D055758:SOX9 Transcription Factor; C527932:SOX9 protein, human; C527933:Sox9 protein, mouse; D015534:Trans-Activators; D014157:Transcription Factors