title: Disruption of gastrulation and oral-aboral ectoderm differentiation in the Lytechinus pictus embryo by a dominant/negative PDGF receptor.
abstract: Little is known about the cell signaling involved in forming the body plan of the sea urchin embryo. Previous work suggested that PDGF-like and EGF-like receptor-mediated signaling pathways are involved in gastrulation and spiculogenesis in the Lytechinus pictus embryo. Here we show that expression of the human PDGF receptor-beta lacking the cytoplasmic domain disrupted development in a manner consistent with a dominant/negative mechanism. The truncated PDGF receptor-beta inhibited gut and spicule formation and differentiation along the oral-aboral axis. The most severely affected embryos arrested at a developmental stage resembling mesenchyme blastula. Coinjection into eggs of RNA encoding the entire human PDGF receptor-beta rescued development. The truncated PDGF receptor-beta caused the aboral ectoderm-specific genes LpS1 and LpC2 to be repressed while an oral ectoderm-specific gene, Ecto-V, was expressed in all ectoderm cells. The results support the hypothesis that a PDGF-like signaling pathway plays a key role in the intercellular communication required for gastrulation and spiculogenesis, and in cell commitment and differentiation along the oral-aboral axis.
authors.affiliation: Department of Biology, The University of Houston, TX 77204-5513, USA.
authors.forename: R K
authors.initials: RK
authors.lastname: Ramachandran
authors.forename: A H
authors.initials: AH
authors.lastname: Wikramanayake
authors.forename: J A
authors.initials: JA
authors.lastname: Uzman
authors.forename: V
authors.initials: V
authors.lastname: Govindarajan
authors.forename: C R
authors.initials: CR
authors.lastname: Tomlinson
mesh_terms: D000818:Animals; D001665:Binding Sites; D002454:Cell Differentiation / Q000235:genetics; D004475:Ectoderm / Q000502:physiology*; D004625:Embryo, Nonmammalian / Q000502:physiology; D004627:Embryonic Induction / Q000235:genetics; D005775:Gastrula / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D005799:Genes, Dominant; D006801:Humans; D008845:Microinjections; D008958:Models, Molecular; D012313:RNA; D017479:Receptors, Platelet-Derived Growth Factor / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012617:Sea Urchins / Q000196:embryology*; D015398:Signal Transduction
chemical_list: D011994:Recombinant Proteins; D012313:RNA; D017479:Receptors, Platelet-Derived Growth Factor