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XB-ART-44589
BMC Dev Biol November 15, 2011; 11 74.

The response of early neural genes to FGF signaling or inhibition of BMP indicate the absence of a conserved neural induction module.

Rogers CD , Ferzli GS , Casey ES .


Abstract
The molecular mechanism that initiates the formation of the vertebrate central nervous system has long been debated. Studies in Xenopus and mouse demonstrate that inhibition of BMP signaling is sufficient to induce neural tissue in explants or ES cells respectively, whereas studies in chick argue that instructive FGF signaling is also required for the expression of neural genes. Although additional signals may be involved in neural induction and patterning, here we focus on the roles of BMP inhibition and FGF8a. To address the question of necessity and sufficiency of BMP inhibition and FGF signaling, we compared the temporal expression of the five earliest genes expressed in the neuroectoderm and determined their requirements for induction at the onset of neural plate formation in Xenopus. Our results demonstrate that the onset and peak of expression of the genes vary and that they have different regulatory requirements and are therefore unlikely to share a conserved neural induction regulatory module. Even though all require inhibition of BMP for expression, some also require FGF signaling; expression of the early-onset pan-neural genes sox2 and foxd5α requires FGF signaling while other early genes, sox3, geminin and zicr1 are induced by BMP inhibition alone. We demonstrate that BMP inhibition and FGF signaling induce neural genes independently of each other. Together our data indicate that although the spatiotemporal expression patterns of early neural genes are similar, the mechanisms involved in their expression are distinct and there are different signaling requirements for the expression of each gene.

PubMed ID: 22172147
PMC ID: PMC3271986
Article link: BMC Dev Biol
Grant support: [+]
Genes referenced: bmp4 eef1a2 fgf8 fgfr1 foxd4l1.1 gem gmnn msx1 neurog2 nog odc1 pnma2 snai2 sox2 sox3 tbxt tub tubb2b ventx1.2 ventx2.2


Article Images: [+] show captions
References [+] :
Albazerchi, A role for the hypoblast (AVE) in the initiation of neural induction, independent of its ability to position the primitive streak. 2007, Pubmed


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