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.
Publication types
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Avian Proteins
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Basic Helix-Loop-Helix Transcription Factors
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Body Patterning / genetics*
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Bone and Bones / embryology
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Chick Embryo
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Chimera
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism*
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Fibroblast Growth Factors / metabolism
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Gene Expression Regulation, Developmental / genetics
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Muscle, Skeletal / embryology
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Paired Box Transcription Factors
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Protein Structure, Tertiary / genetics
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Quail
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Receptor Protein-Tyrosine Kinases / metabolism
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Receptor, Fibroblast Growth Factor, Type 4
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Receptors, Fibroblast Growth Factor / metabolism
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Recombinant Fusion Proteins
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Silencer Elements, Transcriptional / genetics
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Somites / cytology
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Somites / metabolism*
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Stem Cells / cytology
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Stem Cells / metabolism*
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Tendons / cytology
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Tendons / embryology*
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Tendons / metabolism*
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Transcription Factors / genetics
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Transcription Factors / metabolism*
Substances
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Avian Proteins
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Basic Helix-Loop-Helix Transcription Factors
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DNA-Binding Proteins
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Paired Box Transcription Factors
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Receptors, Fibroblast Growth Factor
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Recombinant Fusion Proteins
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SCX protein, Gallus gallus
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Transcription Factors
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PAX1 transcription factor
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Fibroblast Growth Factors
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FGFR4 protein, Coturnix coturnix
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Receptor Protein-Tyrosine Kinases
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Receptor, Fibroblast Growth Factor, Type 4