title: A somitic compartment of tendon progenitors.
abstract: We demonstrate that the tendons associated with the axial skeleton derive from a heretofore unappreciated, fourth compartment of the somites. Scleraxis (Scx), a bHLH transcription factor, marks this somitic tendon progenitor population at its inception, and is continuously expressed through differentiation into the mature tendons. Two earlier-formed somitic compartments, the sclerotome and myotome, interact to establish this fourth Scx-positive compartment. The tendon progenitors are induced at the sclerotome's edge, at the expense of skeletogenic Pax1 positive cells and in response to FGF signaling in the adjacent myotome. The tendon primordia thus form in a location abutting the two tissues that the mature tendons must ultimately connect. Tendon progenitor formation may reveal a general mechanism for the specification of other somitic subcompartments.
authors.affiliation: Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Ava E
authors.initials: AE
authors.lastname: Brent
authors.forename: Ronen
authors.initials: R
authors.lastname: Schweitzer
authors.forename: Clifford J
authors.initials: CJ
authors.lastname: Tabin
mesh_terms: D000818:Animals; D030161:Avian Proteins; D051792:Basic Helix-Loop-Helix Proteins; D019521:Body Patterning / Q000235:genetics*; D001842:Bone and Bones / Q000196:embryology; D002642:Chick Embryo; D002678:Chimera; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005346:Fibroblast Growth Factors / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D018482:Muscle, Skeletal / Q000196:embryology; D051761:Paired Box Transcription Factors; D017434:Protein Structure, Tertiary / Q000235:genetics; D011784:Quail; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D051499:Receptor, Fibroblast Growth Factor, Type 4; D017468:Receptors, Fibroblast Growth Factor / Q000378:metabolism; D011993:Recombinant Fusion Proteins; D037941:Silencer Elements, Transcriptional / Q000235:genetics; D019170:Somites / Q000166:cytology / Q000378:metabolism*; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D013710:Tendons / Q000166:cytology / Q000196:embryology* / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D030161:Avian Proteins; D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D005346:Fibroblast Growth Factors; D051761:Paired Box Transcription Factors; D020794:Receptor Protein-Tyrosine Kinases; D051499:Receptor, Fibroblast Growth Factor, Type 4; D017468:Receptors, Fibroblast Growth Factor; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C503821:SCX protein, Gallus gallus; C070835:PAX1 transcription factor; C086864:FGFR4 protein, Coturnix coturnix