title: Scx+/Sox9+ progenitors contribute to the establishment of the junction between cartilage and tendon/ligament.
abstract: SRY-box containing gene 9 (Sox9) and scleraxis (Scx) regulate cartilage and tendon formation, respectively. Here we report that murine Scx(+)/Sox9(+) progenitors differentiate into chondrocytes and tenocytes/ligamentocytes to form the junction between cartilage and tendon/ligament. Sox9 lineage tracing in the Scx(+) domain revealed that Scx(+) progenitors can be subdivided into two distinct populations with regard to their Sox9 expression history: Scx(+)/Sox9(+) and Scx(+)/Sox9(-) progenitors. Tenocytes are derived from Scx(+)/Sox9(+) and Scx(+)/Sox9(-) progenitors. The closer the tendon is to the cartilaginous primordium, the more tenocytes arise from Scx(+)/Sox9(+) progenitors. Ligamentocytes as well as the annulus fibrosus cells of the intervertebral discs are descendants of Scx(+)/Sox9(+) progenitors. Conditional inactivation of Sox9 in Scx(+)/Sox9(+) cells causes defective formation in the attachment sites of tendons/ligaments into the cartilage, and in the annulus fibrosus of the intervertebral discs. Thus, the Scx(+)/Sox9(+) progenitor pool is a unique multipotent cell population that gives rise to tenocytes, ligamentocytes and chondrocytes for the establishment of the chondro-tendinous/ligamentous junction.
authors.affiliation: Department of Cellular Differentiation, Institute for Frontier Medical Sciences, Kyoto University, Kyoto 606-8507, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Sugimoto
authors.forename: Aki
authors.initials: A
authors.lastname: Takimoto
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Akiyama
authors.forename: Ralf
authors.initials: R
authors.lastname: Kist
authors.forename: Gerd
authors.initials: G
authors.lastname: Scherer
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakamura
authors.forename: Yuji
authors.initials: Y
authors.lastname: Hiraki
authors.forename: Chisa
authors.initials: C
authors.lastname: Shukunami
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics* / Q000378:metabolism; D001842:Bone and Bones / Q000502:physiology; D002356:Cartilage / Q000254:growth & development*; D018507:Gene Expression Regulation, Developmental; D008022:Ligaments / Q000254:growth & development*; D008648:Mesoderm / Q000254:growth & development; D051379:Mice; D008822:Mice, Transgenic; D055758:SOX9 Transcription Factor / Q000235:genetics* / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology*; D013710:Tendons / Q000254:growth & development*
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D055758:SOX9 Transcription Factor; C503815:Scx protein, mouse; C527933:Sox9 protein, mouse
keywords: Chondrocytes; Ligamentocytes; Mouse; Scx; Sox9; Tenocytes