title: Off limits--integrins holding boundaries in somitogenesis.
abstract: Borders are essential for demarcating repeated structures such as somites during vertebrate development. Two recent articles describe roles for Integrinalpha5 and its ligand Fibronectin1 in zebrafish anterior intersomitic boundary formation and link them to Notch and Eph-Ephrin pathways in epithelialization of somite boundary cells. Together with these pathways, Integrinalpha5 and Fibronectin1 orchestrate the orderly formation of somite and later myotome borders. These studies shed light on components downstream of the periodic segmentation mechanism - the 'segmentation clock' - in somitogenesis.
authors.affiliation: Laboratory of Developmental Signalling and Patterning, Institute of Molecular and Cell Biology, Proteos, 61 Biopolis Drive, Singapore 138673.
authors.forename: Shang-Wei
authors.initials: SW
authors.lastname: Chong
authors.forename: Yun-Jin
authors.initials: YJ
authors.lastname: Jiang
mesh_terms: D000818:Animals; D036342:Ephrins / Q000502:physiology; D004848:Epithelium / Q000196:embryology; D005353:Fibronectins / Q000502:physiology; D018398:Homeodomain Proteins / Q000502:physiology; D039482:Integrin alpha5 / Q000502:physiology; D016023:Integrins / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000502:physiology; D051881:Receptor, Notch1 / Q000502:physiology; D036081:Receptors, Eph Family / Q000502:physiology; D019170:Somites / Q000502:physiology*; D015027:Zebrafish / Q000196:embryology*; D029961:Zebrafish Proteins / Q000502:physiology
chemical_list: D036342:Ephrins; D005353:Fibronectins; D018398:Homeodomain Proteins; D039482:Integrin alpha5; D016023:Integrins; D009419:Nerve Tissue Proteins; D051881:Receptor, Notch1; D029961:Zebrafish Proteins; C468126:dld protein, zebrafish; C437805:notch1a protein, zebrafish; D036081:Receptors, Eph Family