The Xenopus Ets transcription factor XER81 is a target of the FGF signaling pathway

We report the cloning of a cDNA encoding a Xenopus laevis Ets-type transcri ption factor. This new Xenopus gene belongs to the PEA3 subfamily of Ets pr oteins and shows the highest degree of sequence similarity to the mouse and human ER81 genes. The Xenopus ER81 gene (XER81) is transcribed in the embr yo after mid blastula transition (MBT) and three transcripts of 3, 4 and 6 kb are detected throughout embryogenesis. XER81 mRNA is localized in the an imal pole of the late blastula stage and higher levels of XER81 transcripts are detected in the marginal zone at the onset of gastrulation. In later e mbryogenesis XER81 transcripts are found in neural crest cells, eyes, otic vesicles and pronephros. The transcription of XER81 can be stimulated by bF GF and eFGF in animal and vegetal cap explants. Expression of the dominant negative FGF receptor mutant in animal caps and embryos blocks XER81 transc ription, arguing that the expression of this Ets gene requires active FGF s ignaling. The spatial overlap of eFGF and XER81 expression domains supports the idea that XER81 transcription could be a marker for regions with activ e FGF signaling in the embryo. (C) 1999 Elsevier Science Ireland Ltd. All r ights reserved.