RUI: Expression and Regulation of a Novel Xenopus FGF-Receptor mRNA

非洲爪蟾胚胎中胚层的诱导是由许多可扩散信号介导的，包括成纤维细胞生长因子（FGF）信号分子家族的成员。FGF家族成员在体外表现出诱导中胚层的活性，FGF在胚胎发育的适当时间和位置表达，FGF受体的失活导致体内中胚层形成的缺陷。FGF信号通路与其他被认为在中胚层诱导中起作用的信号通路（包括tgf - β超家族成员）相互作用，尽管这些相互作用的性质尚不清楚。该计划的重点是cDNA克隆编码一种新的FGF受体，称为F37，从早期非洲爪蟾胚胎。初步数据显示，F37 mRNA存在于未受精卵中，并在早期发育过程中保持存在，与其同源的FGF受体在中胚层诱导中的作用一致。由于迄今为止的实验表明，在中胚层诱导期间，非洲爪蟾胚胎中只存在一种FGF受体，第二种FGF受体mRNA的存在表明，FGF与不同FGF受体的结合或不同FGF受体之间的相互作用可能在中胚层的诱导或定型中发挥作用。我们将分离一个全长F37克隆，对其进行测序，并利用RNA印迹和全载原位杂交技术对其胚胎表达模式进行时间和空间的表征。为了确定F37的表达调控是否与先前表征的爪蟾FGF受体相似或不同，我们将通过几种方法分析所有爪蟾FGF受体mrna的表达。利用RNA印迹技术，1)确定分离动物帽中FGF受体mrna的表达模式；2)发育过程中各种FGF受体mrna的聚腺苷化（和可能的翻译）的时间将被确定。最后，实验将验证FGF受体的过度表达可以延长中胚层诱导反应的能力期的假设。* * *

9507049 Servetnick Mesoderm induction in Xenopus laevis embryos is mediated by a number of diffusible signals, including members of the fibroblast growth factor (FGF) family of signalling molecules. Members of the FGF family show mesoderm inducing activity in vitro, FGF's are expressed at the appropriate time and place in embryonic development, and inactivation of FGF receptors leads to defects in mesoderm formation in vivo. The FGF signalling pathway interacts with other signalling pathways that are thought to operate in mesoderm induction (including members of the TGF-beta superfamily), though the nature of these interactions is poorly understood. The proposed project focuses on a cDNA clone encoding a novel FGF receptor, termed F37, from early Xenopus embryos. Preliminary data show that F37 mRNA is present in the unfertilized egg, and remains present through early development, consistent with a role for its cognate FGF receptor in mesoderm induction. Because experiments to date have characterized only a single FGF receptor present in the Xenopus embryo during the period of mesoderm induction, the presence of this second FGF receptor mRNA suggests that binding of FGF's to different FGF receptors, or the interactions between different FGF receptors, may play a role in the induction or patterning of mesoderm. A full length F37 clone will be isolated, sequenced, and its embryonic expression pattern will be characterized both temporally and spatially, using RNA blots and whole mount is situ hybridization. To determine whether the regulation of F37 expression is similar to, or different from, previously characterized Xenopus FGF receptors, the expression of all the Xenopus FGF receptor mRNAs will be analyzed in several ways. Using RNA blots, 1) the expression pattern of the FGF receptor mRNAs in isolated animal caps will be determined; and 2) the timing of polyadenylation (and presumably translation) of the various FGF receptor mRNAs during development will be determined. Finally, experiments will be performed to test the hypothesis that over expression of FGF receptors can extend the period of competence to respond to mesoderm induction. ***