Ramachandran R K, Wikramanayake A H, Uzman J A, Govindarajan V, Tomlinson C R
Department of Biology, The University of Houston, TX 77204-5513, USA.
Development. 1997 Jun;124(12):2355-64. doi: 10.1242/dev.124.12.2355.
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.
关于海胆胚胎形成身体结构所涉及的细胞信号传导，我们了解得很少。先前的研究表明，血小板衍生生长因子（PDGF）样和表皮生长因子（EGF）样受体介导的信号通路参与了花斑背棘海胆胚胎的原肠胚形成和骨针形成过程。在此我们表明，缺失细胞质结构域的人血小板衍生生长因子受体-β（PDGF receptor-beta）的表达以一种与显性/阴性机制一致的方式破坏了胚胎发育。截短的血小板衍生生长因子受体-β抑制了肠道和骨针的形成以及沿口-反口轴的分化。受影响最严重的胚胎停滞在类似于间充质囊胚的发育阶段。将编码完整人血小板衍生生长因子受体-β的RNA共注射到卵中可挽救胚胎发育。截短的血小板衍生生长因子受体-β导致反口外胚层特异性基因LpS1和LpC2被抑制，而口外胚层特异性基因Ecto-V在所有外胚层细胞中均有表达。这些结果支持了这样一种假说，即血小板衍生生长因子样信号通路在原肠胚形成和骨针形成所需的细胞间通讯中，以及在沿口-反口轴的细胞定向和分化中起着关键作用。
