title: Expression of the short stature homeobox gene Shox is restricted by proximal and distal signals in chick limb buds and affects the length of skeletal elements.
abstract: SHOX is a homeobox-containing gene, highly conserved among species as diverse as fish, chicken and humans. SHOX gene mutations have been shown to cause idiopathic short stature and skeletal malformations frequently observed in human patients with Turner, Leri-Weill and Langer syndromes. We cloned the chicken orthologue of SHOX, studied its expression pattern and compared this with expression of the highly related Shox2. Shox is expressed in central regions of early chick limb buds and proximal two thirds of later limbs, whereas Shox2 is expressed more posteriorly in the proximal third of the limb bud. Shox expression is inhibited distally by signals from the apical ectodermal ridge, both Fgfs and Bmps, and proximally by retinoic acid signaling. We tested Shox functions by overexpression in embryos and micromass cultures. Shox-infected chick limbs had normal proximo-distal patterning but the length of skeletal elements was consistently increased. Primary chick limb bud cell cultures infected with Shox showed an initial increase in cartilage nodules but these did not enlarge. These results fit well with the proposed role of Shox in cartilage and bone differentiation and suggest chick embryos as a useful model to study further the role of Shox in limb development.
authors.affiliation: Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH, UK.
authors.forename: Eva
authors.initials: E
authors.lastname: Tiecke
authors.forename: Fiona
authors.initials: F
authors.lastname: Bangs
authors.forename: Rudiger
authors.initials: R
authors.lastname: Blaschke
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Farrell
authors.forename: Gudrun
authors.initials: G
authors.lastname: Rappold
authors.forename: Cheryll
authors.initials: C
authors.lastname: Tickle
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D002642:Chick Embryo; D018507:Gene Expression Regulation, Developmental; D005801:Genes, Homeobox; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D018878:Limb Buds / Q000033:anatomy & histology / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D008953:Models, Anatomic; D008969:Molecular Sequence Data; D009924:Organ Culture Techniques; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
chemical_list: D018398:Homeodomain Proteins