Abstract
The Xvent homeobox multigene family is essential for the patterning of the ventral mesoderm in Xenopus embryos. We have identified two novel members of this family, Xvent-1B and Xvent-2B, and have characterized their genomic structures. These two genes show a clustered organization and have probably arisen by gene duplication with subsequent inversion. Cis-regulatory elements within the promoters of both genes have been identified which contribute to their spatial activation. Xvent-2B is activated by BMP-2/4 in the absence of de novo protein synthesis, suggesting that this gene is a direct target of BMP-signalling. In contrast, Xvent-1B does not directly respond to BMP-2/4, but is activated by Xvent-2B. This activation is documented by Xvent-1B promoter/reporter studies, Xvent-2B overexpression and loss-of-function analysis using a dominant-negative Xvent-2 mutant. However, cycloheximide experiments reveal that Xvent-2B by itself is not sufficient to activate transcription of the Xvent-1B gene, but that there is a requirement for additional factor(s) being synthesized after midblastula transition.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Bone Morphogenetic Protein 2
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Bone Morphogenetic Protein 4
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Bone Morphogenetic Proteins / metabolism
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Cycloheximide / pharmacology
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Epistasis, Genetic
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Genes, Dominant
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Genes, Regulator / physiology*
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Genomic Library
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Homeodomain Proteins / genetics*
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In Situ Hybridization
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Luciferases / metabolism
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Molecular Sequence Data
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Mutagenesis
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Phenotype
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Promoter Regions, Genetic
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Protein Synthesis Inhibitors / pharmacology
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Recombinant Fusion Proteins
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Reverse Transcriptase Polymerase Chain Reaction
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Sequence Homology, Amino Acid
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Sequence Homology, Nucleic Acid
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Tissue Distribution
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Transcription Factors*
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Transforming Growth Factor beta*
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Xenopus Proteins*
Substances
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Bone Morphogenetic Protein 2
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Bone Morphogenetic Protein 4
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Bone Morphogenetic Proteins
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Homeodomain Proteins
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Protein Synthesis Inhibitors
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Recombinant Fusion Proteins
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Transcription Factors
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Transforming Growth Factor beta
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Xenopus Proteins
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bmp4 protein, Xenopus
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ventx1.2 protein, Xenopus
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ventx2.1 protein, Xenopus
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Cycloheximide
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Luciferases
Associated data
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GENBANK/AJ131094
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GENBANK/AJ131095