Fgf4 positively regulates scleraxis and tenascin expression in chick limb tendons.
In vertebrates, tendons connect muscles to skeletal elements. Surgical experiments in the chick have underlined developmental interactions between tendons and muscles. Initial formation of tendons occurs autonomously with respect to muscle. However, further tendon development requires the presence of muscle. The molecular signals involved in these interactions remain unknown. In the chick limb, Fgf4 transcripts are located at the extremities of muscles, where the future tendons will attach. In this paper, we analyse the putative role of muscle-Fgf4 on tendon development. We have used three general tendon markers, scleraxis, tenascin, and Fgf8 to analyse the regulation of these tendon-associated molecules by Fgf4 under different experimental conditions. In the absence of Fgf4, in muscleless and aneural limbs, the expression of the three tendon-associated molecules, scleraxis, tenascin, and Fgf8, is down-regulated. Exogenous implantation of Fgf4 in normal, aneural, and muscleless limbs induces scleraxis and tenascin expression but not that of Fgf8. These results indicate that Fgf4 expressed in muscle is required for the maintenance of scleraxis and tenascin but not Fgf8 expression in tendons.
Edom-Vovard
Frédérique
F
Institut d'Embryologie Cellulaire et Moléculaire du CNRS et du Collège de France (UMR 7128), 49 bis, avenue de la Belle Gabrielle, Nogent-sur-Marne, 94736, France.
Schuler
Bernadette
B
Bonnin
Marie-Ange
MA
Teillet
Marie-Aimée
MA
Duprez
Delphine
D
D000818:Animals; D030161:Avian Proteins; D051792:Basic Helix-Loop-Helix Proteins; D002642:Chick Embryo; D015536:Down-Regulation; D005121:Extremities / Q000196:embryology*; D051519:Fibroblast Growth Factor 4; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D009132:Muscles / Q000196:embryology; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D019063:Tenascin / Q000378:metabolism*; D013997:Time Factors; D014157:Transcription Factors / Q000096:biosynthesis*; D015854:Up-Regulation; D014921:Wings, Animal / Q000196:embryology
D030161:Avian Proteins; D051792:Basic Helix-Loop-Helix Proteins; D051519:Fibroblast Growth Factor 4; D005346:Fibroblast Growth Factors; D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins; D019063:Tenascin; D014157:Transcription Factors; C503821:SCX protein, Gallus gallus