Mode of action of VegT in mesoderm and endoderm formation.
mRNA encoding the T-box transcription factor VegT is located throughout the vegetal pole of the Xenopus egg and is believed to play an important part in endoderm and mesoderm formation. We find that VegT generates endoderm both by cell-autonomous action and by generating TGF-beta family signals, the latter being entirely responsible for its mesoderm-inducing activity. Signalling molecules induced cell-autonomously by VegT include derrière, Xnr4 and activin B. Xnr1 and Xnr2 are also induced, but primarily in a non-autonomous manner. All of these signalling molecules are found in the blastula and gastrula vegetal pole and induce both endoderm and mesoderm in the animal cap assay, and hence are good candidates both for the endogenous zygotic mesoderm-inducing signal and for reinforcing the vegetal expression of endoderm markers.
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Department of Biological Sciences, University of Warwick, Coventry, CV4 7AL, UK. hw@dna.bio.warwick.ac.uk.
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D028341:Activins; D000818:Animals; D004268:DNA-Binding Proteins; D004625:Embryo, Nonmammalian; D004627:Embryonic Induction; D004707:Endoderm / Q000502:physiology*; D005326:Fetal Proteins; D018507:Gene Expression Regulation, Developmental; D006133:Growth Substances / Q000235:genetics / Q000378:metabolism; D006609:High Mobility Group Proteins; D036341:Intercellular Signaling Peptides and Proteins; D008648:Mesoderm / Q000502:physiology*; D055456:Nodal Signaling Ligands; D009842:Oligopeptides; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D055760:SOXF Transcription Factors; D015398:Signal Transduction; D020825:T-Box Domain Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism; D014981:Xenopus / Q000196:embryology*; D029867:Xenopus Proteins; D015053:Zygote; D000098908:Brachyury Protein
D028341:Activins; D004268:DNA-Binding Proteins; D005326:Fetal Proteins; D006133:Growth Substances; D006609:High Mobility Group Proteins; D036341:Intercellular Signaling Peptides and Proteins; D055456:Nodal Signaling Ligands; D009842:Oligopeptides; D010455:Peptides; D011506:Proteins; D055760:SOXF Transcription Factors; D020825:T-Box Domain Proteins; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D029867:Xenopus Proteins; D000098908:Brachyury Protein; C118849:GDF3 protein, Xenopus; C105817:NODAL protein, Xenopus; C113775:Ndr2 protein, vertebrate; C485173:STK38L protein, Xenopus; C103966:VegT protein, Xenopus; C044147:activin B; C512833:nodal1 protein, Xenopus; C491602:sox17a protein, Xenopus; C491601:sox17b.1 protein, Xenopus; C048617:myelopeptides