title: Morphogenesis of prechordal plate and notochord requires intact Eph/ephrin B signaling.
abstract: Eph receptors and their ligands, the ephrins, mediate cell-to-cell signals implicated in the regulation of cell migration processes during development. We report the molecular cloning and tissue distribution of zebrafish transmembrane ephrins that represent all known members of the mammalian class B ephrin family. The degree of homology among predicted ephrin B sequences suggests that, similar to their mammalian counterparts, zebrafish B-ephrins can also bind promiscuously to several Eph receptors. The dynamic expression patterns for each zebrafish B-ephrin support the idea that these ligands are confined to interact with their receptors at the borders of their complementary expression domains. Zebrafish B-ephrins are expressed as early as 30% epiboly and during gastrula stages: in the germ ring, shield, prechordal plate, and notochord. Ectopic overexpression of dominant-negative soluble ephrin B constructs yields reproducible defects in the morphology of the notochord and prechordal plate by the end of gastrulation. Notably disruption of Eph/ephrin B signaling does not completely destroy structures examined, suggesting that cell fate specification is not altered. Thus abnormal morphogenesis of the prechordal plate and the notochord is likely a consequence of a cell movement defect. Our observations suggest Eph/ephrin B signaling plays an essential role in regulating cell movements during gastrulation.
authors.affiliation: Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA. jochan@mbcrr.harvard.edu
authors.forename: J
authors.initials: J
authors.lastname: Chan
authors.forename: J D
authors.initials: JD
authors.lastname: Mably
authors.forename: F C
authors.initials: FC
authors.lastname: Serluca
authors.forename: J N
authors.initials: JN
authors.lastname: Chen
authors.forename: N B
authors.initials: NB
authors.lastname: Goldstein
authors.forename: M C
authors.initials: MC
authors.lastname: Thomas
authors.forename: J A
authors.initials: JA
authors.lastname: Cleary
authors.forename: C
authors.initials: C
authors.lastname: Brennan
authors.forename: M C
authors.initials: MC
authors.lastname: Fishman
authors.forename: T M
authors.initials: TM
authors.lastname: Roberts
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019521:Body Patterning; D002465:Cell Movement; D004475:Ectoderm; D004628:Embryonic Structures / Q000196:embryology*; D005775:Gastrula; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D009024:Morphogenesis; D009420:Nervous System / Q000196:embryology; D009672:Notochord / Q000196:embryology*; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014018:Tissue Distribution; D015027:Zebrafish
chemical_list: D008565:Membrane Proteins; D020794:Receptor Protein-Tyrosine Kinases