Fox (forkhead) genes are involved in the dorso-ventral patterning of the Xenopus mesoderm

Fox (forkhead/winged helix) genes encode a family of transcription factors that are involved in embryonic pattern formation, regulation of tissue spec ific gene expression and tumorigenesis. Several of them are transcribed dur ing Xenopus embryogenesis and are important for the patterning of ectoderm, mesoderm and endoderm. We have isolated three forkhead genes that are acti vated during gastrulation and play an important role in the dorso-ventral p atterning of the mesoderm. XFKH1(FoxA4b), the first vertebrate forkhead gen e to be implicated in embryonic pattern formation, is expressed in the Spem ann-Mangold organizer region and later in the embryonic notochord. XFKH7, t he Xenopus orthologue of the murine Mfh1(Foxc2), is expressed in the presom itic mesoderm, but not in the notochord or lateral plate mesoderm. Finally, XFD13'(FoxF1b)1 is expressed in the lateral plate mesoderm, but not in the notochord or presomitic mesoderm. Expression pattern and functional experi ments indicate that these three forkhead genes are involved in the dorso-ve ntral patterning of the mesoderm.