title: Control of extracellular matrix assembly along tissue boundaries via Integrin and Eph/Ephrin signaling.
abstract: Extracellular matrixes (ECMs) coat and subdivide animal tissues, but it is unclear how ECM formation is restricted to tissue surfaces and specific cell interfaces. During zebrafish somite morphogenesis, segmental assembly of an ECM composed of Fibronectin (FN) depends on the FN receptor Integrin alpha5beta1. Using in vivo imaging and genetic mosaics, our studies suggest that incipient Itgalpha5 clustering along the nascent border precedes matrix formation and is independent of FN binding. Integrin clustering can be initiated by Eph/Ephrin signaling, with Ephrin reverse signaling being sufficient for clustering. Prior to activation, Itgalpha5 expressed on adjacent cells reciprocally and non-cell-autonomously inhibits spontaneous Integrin clustering and assembly of an ECM. Surface derepression of this inhibition provides a self-organizing mechanism for the formation and maintenance of ECM along the tissue surface. Within the tissue, interplay between Eph/Ephrin signaling, ligand-independent Integrin clustering and reciprocal Integrin inhibition restricts de novo ECM production to somite boundaries.
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA.
authors.forename: Dörthe
authors.initials: D
authors.lastname: Jülich
authors.forename: A Paul
authors.initials: AP
authors.lastname: Mould
authors.forename: Ewa
authors.initials: E
authors.lastname: Koper
authors.forename: Scott A
authors.initials: SA
authors.lastname: Holley
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D036342:Ephrins / Q000235:genetics / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism; D006801:Humans; D039081:Integrin alpha5beta1 / Q000235:genetics / Q000378:metabolism*; D009024:Morphogenesis / Q000502:physiology*; D016376:Oligonucleotides, Antisense / Q000235:genetics / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D036081:Receptors, Eph Family / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction / Q000502:physiology; D019170:Somites / Q000033:anatomy & histology / Q000502:physiology*; D015027:Zebrafish / Q000033:anatomy & histology / Q000196:embryology; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D036342:Ephrins; D005353:Fibronectins; D039081:Integrin alpha5beta1; D016376:Oligonucleotides, Antisense; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; D029961:Zebrafish Proteins; D036081:Receptors, Eph Family