Alvarez I S, Araujo M, Nieto M A
Departamento de Biología Celular, Facultad de Ciencias, Universidad de Extremadura, Badajoz, Spain.
Dev Biol. 1998 Jul 1;199(1):42-54. doi: 10.1006/dbio.1998.8903.
FGFs are well known as mesodermal inducers and they have been reported to have neural inducing and/or caudalizing activity in Xenopus. To evaluate the role of FGFs in neural induction and patterning of the nervous system in chick embryos, we have targeted the ectopic expression of these factors by applying FGF-soaked beads to extended primitive streak chick embryos developing in culture. The whole embryo culture system allows to directly assessing the neural inducing activity on nonneural ectodermal cells. Our results show that FGFs induce the production of ectopic neural structures in the epiblast cell layer which are independent of the endogenous neural tube. The induced neural plates express several neural positional markers (Otx-2, Krox-20, EphA4, EphA7, and cHox-B9), although they lack anterior neural markers such as BF-1. These effects are very likely to be exerted by the direct action of FGF on epiblast cells because we have found no evidence of the induction of an organizer-like activity or of the presence of new axial mesoderm induced by the growth factor. We conclude that FGFs can act as direct neural inducers and that this action is exerted independently from the axial mesoderm.
成纤维细胞生长因子（FGFs）作为中胚层诱导因子广为人知，据报道，它们在非洲爪蟾中具有神经诱导和/或尾化活性。为了评估FGFs在鸡胚神经系统神经诱导和模式形成中的作用，我们通过将浸泡过FGF的珠子应用于在培养中发育的延长原条鸡胚，来靶向这些因子的异位表达。全胚胎培养系统能够直接评估对非神经外胚层细胞的神经诱导活性。我们的结果表明，FGFs诱导上胚层细胞层中异位神经结构的产生，这些结构独立于内源性神经管。诱导的神经板表达几种神经位置标记物（Otx-2、Krox-20、EphA4、EphA7和cHox-B9），尽管它们缺乏诸如BF-1等前神经标记物。这些效应很可能是由FGF对上胚层细胞的直接作用所产生的，因为我们没有发现诱导组织者样活性或生长因子诱导新的轴向中胚层存在的证据。我们得出结论，FGFs可以作为直接的神经诱导因子，并且这种作用独立于轴向中胚层发挥。
