Abstract
Mutations in the Tbx5 transcription factor cause heart septal defects found in human Holt-Oram Syndrome. The complete extent to which Tbx5 functions in heart development, however, has not been established. Here we show that, in Xenopus embryos, Tbx5 is expressed in the early heart field, posterior to the cardiac homeobox transcription factor, Nkx2.5. During morphogenesis, Tbx5 is expressed throughout the heart tube except the anterior portion, the bulbus cordis. When Tbx5 activity is antagonized with a hormone-inducible, dominant negative version of the protein, the heart fails to develop. These results suggest that, in addition to its function in heart septation, Tbx5 has a more global role in cardiac specification and heart development in vertebrate embryos.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Animals
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Base Sequence
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DNA, Complementary
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Eye / embryology
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Eye / metabolism
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Gene Expression
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Genes, Overlapping
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Heart / embryology*
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Homeobox Protein Nkx-2.5
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Homeodomain Proteins / genetics
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Homeodomain Proteins / metabolism
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Hormones / pharmacology
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Humans
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Mesoderm
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Mice
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Molecular Sequence Data
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Morphogenesis
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Phenotype
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Receptors, Glucocorticoid / metabolism
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T-Box Domain Proteins*
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Transcription Factors / genetics
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Transcription Factors / physiology*
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Xenopus Proteins*
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Xenopus laevis / embryology
Substances
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DNA, Complementary
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Homeobox Protein Nkx-2.5
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Homeodomain Proteins
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Hormones
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NKX2-5 protein, Xenopus
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NKX2-5 protein, human
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Nkx2-5 protein, mouse
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Receptors, Glucocorticoid
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T-Box Domain Proteins
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T-box transcription factor 5
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Transcription Factors
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Xenopus Proteins