New perspectives on the role of the fibroblast gro

Authors: H V Isaacs

Publish Date: 2014/01/29

Volume: 53, Issue: 4, Pages: 350-361

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Abstract

It has been known for several years that the fibroblast growth factors FGFs have potent mesoderminducing activity As a result they have been considered good candidates for one of the endogenous vegetally localized mesoderminducing signals in the amphibian Xenopus laevis In this review the properties of the FGFs and their expression patterns in Xenopus are described Recent work is discussed which reveals a close link between FGF signalling and regulation of the Xenopus brachyury Xbra gene These data are used to build a model of FGF function which is quite different from what was originally conceived Present evidence supports the view that during blastula stages the FGFs do not act as vegetally localized inducing signals Instead they are required in the animal hemisphere as competence factors which provide a low level stimulation of the tyrosine kinase signal transduction pathway FGF activity is necessary for the full range of responses to the vegetal inducing signals including the activation of Xbra transcription in the marginal zone of the late blastula Xbra is able to activate the zygotic transcription of eFGF which suggests that there is a period of autocatalytic activation of eFGF and Xbra transcription within the forming mesoderm of the marginal zone FGF activity continues to be required to maintain the expression of a subset of mesodermal genes including Xbra in the blastopore region and possibly also in the notochord through gastrula and neurula stages In addition a role for the FGFs in anteroposterior specification and development of the myogenic lineages is discussed

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