Functional interaction of vega2 and goosecoid homeobox genes in zebrafish.
The gastrula organizer forms in the dorsal region of the zebrafish embryo, where the bozozok/dharma homeobox gene downregulates expression of the vega1 transcriptional repressor. Here, we describe a novel Vega family homeobox gene, vega2. Expression of vega2 is initiated at the ventral blastoderm margin during blastula stages, and by gastrulation becomes complementary to but partially overlapping with the dorsal expression domain of the homeobox gene goosecoid (gsc). This dorsal exclusion of vega2 expression is not observed in bozozok mutants in which organizer formation is impaired. Both vega2 and vega1 can physically interact with Gsc. Zebrafish embryos injected with vega2 mRNA failed to express gsc and developed a headless phenotype. Conversely, a putative dominant negative form of vega2, VP16-vega2, elicited the expansion of gsc expression and a dorsalized phenotype. We suggest that vega2, in cooperation with vega1, functions as a negative regulator of organizer genes including gsc, and participates in the refinement of the gastrula organizer domain.
Kawahara
A
A
Laboratory of Molecular Genetics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA.
Wilm
T
T
Solnica-Krezel
L
L
Dawid
I B
IB
D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D019521:Body Patterning / Q000502:physiology*; D004625:Embryo, Nonmammalian / Q000196:embryology / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D051956:Goosecoid Protein; D018398:Homeodomain Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008156:Luciferases / Q000378:metabolism; D008969:Molecular Sequence Data; D016296:Mutagenesis; D020897:Organizers, Embryonic / Q000196:embryology / Q000502:physiology*; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors; D014162:Transfection; D015027:Zebrafish / Q000196:embryology* / Q000235:genetics; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*
D051956:Goosecoid Protein; D018398:Homeodomain Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D029961:Zebrafish Proteins; C497995:gsc protein, zebrafish; C434250:vent protein, zebrafish; D008156:Luciferases