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SOX7 is an immediate-early target of Veg ... ated gene expression in Xenopus
SOX7 is an immediate-early target of VegT and regulates Nodal-related gene expression in Xenopus.
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In zebrafish, the divergent F-type SOX casanova acts downstream of Nodal signaling to specify endoderm. While no casanova orthologs have been identified in tetrapods, the F-type SOX, SOX7, is supplied maternally in Xenopus (Fawcett and Klymkowsky, 2004. GER 4, 29). Subsequent RT-PCR and section-based in situ hybridization analyses indicate that SOX7 mRNA is localized to the vegetal region of the blastula-stage embryo. Overexpression and maternal depletion studies reveal that the T-box transcription factor VegT, which initiates mesoendodermal differentiation, directly regulates SOX7 expression. SOX7, but not SOX17 (another F-type SOX), binds to sites within the Xnr5 promoter and SOX7, but not SOX17, induces expression of the Nodal-related genes Xnr1, Xnr2, Xnr4, Xnr5, and Xnr6, the homeodomain transcription factor Mixer, and the endodermal marker SOX17beta; both SOX7 and SOX17 induce expression of the pan-endodermal marker endodermin. SOX7's induction of Xnr expression in animal caps is independent of Mixer and Nodal signaling. In animal caps, VegT's ability to induce Mixer and Edd appears to depend upon SOX7 activity. Whole embryo experiments suggests that vegetal factors partially compensate for the absence of SOX7. Based on the antagonistic effects of SOX7 and SOX3 (Zhang et al., 2004. Dev. Biol. 273, 23) and their common binding sites in the Xnr5 promoter, we propose a model in which competitive interactions between these two proteins are involved in refining the domain of endodermal differentiation.
Zhang C, Basta T, Fawcett SR, Klymkowsky MW
Developmental biology
2005-02-15 00:00
278
2
526-41
Amino Acid Sequence,Animals,Base Sequence,DNA Primers,DNA-Binding Proteins,Embryo, Nonmammalian,Endoderm,Female,Fertilization,Gene Deletion,Gene Expression Regulation, Developmental,High Mobility Group Proteins,Humans,Mice,Molecular Sequence Data,Phylogeny,Sequence Alignment,Sequence Homology, Amino Acid,T-Box Domain Proteins,Transcription Factors,Transforming Growth Factor beta,Xenopus Proteins,Xenopus laevis,DNA Primers,DNA-Binding Proteins,High Mobility Group Proteins,T-Box Domain Proteins,Transcription Factors,Transforming Growth Factor beta,VegT protein, Xenopus,XSox7 protein, Xenopus,Xenopus Proteins,nodal protein
Molecular, Cellular and Developmental Biology, University of Colorado, Porter Biosci Building, Boulder, CO 80309-0347, USA
Dev. Biol.
NIGMS GM54001
0012-1606
10.1016/j.ydbio.2004.11.008
S0012-1606(04)00800-0
637
True
15680368
