Abstract
The cardiac homeobox transcription factor CSX/NKX2-5 plays an important role in vertebrate heart development. Using a yeast two-hybrid screening, we identified a novel LIM domain-containing protein, named CSX-associated LIM protein (Cal), that interacts with CSX/NKX2-5. CSX/NKX2-5 and Cal associate with each other both in vivo and in vitro, and the LIM domains of Cal and the homeodomain of CSX/NKX2-5 were necessary for mutual binding. Cal itself possessed the transcription-promoting activity, and cotransfection of Cal enhanced CSX/NKX2-5-induced activation of atrial natriuretic peptide gene promoter. Cal contained a functional nuclear export signal and shuttled from the cytoplasm into the nucleus in response to calcium. Accumulation of Cal in the nucleus of P19CL6 cells promoted myocardial cell differentiation accompanied by increased expression levels of the target genes of CSX/NKX2-5. These results suggest that a novel LIM protein Cal induces cardiomyocyte differentiation through its dynamic intracellular shuttling and association with CSX/NKX2-5.
Copyright The Rockefeller University Press
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Active Transport, Cell Nucleus / physiology
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Amino Acid Sequence
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Animals
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Atrial Natriuretic Factor / genetics
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Atrial Natriuretic Factor / metabolism
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Calcium / metabolism
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Cell Adhesion Molecules
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Cell Differentiation / physiology*
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Cells, Cultured
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Cytoskeletal Proteins
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Embryo, Mammalian / anatomy & histology
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Embryo, Mammalian / physiology
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Heart / growth & development*
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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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Humans
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LIM Domain Proteins
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Macromolecular Substances
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Mice
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Molecular Sequence Data
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Myocytes, Cardiac / cytology
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Myocytes, Cardiac / physiology*
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Promoter Regions, Genetic
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Protein Binding
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Rats
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Rats, Wistar
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Recombinant Fusion Proteins / metabolism
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Tissue Distribution
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Trans-Activators / genetics
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Trans-Activators / metabolism*
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Transcription Factors / genetics
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Transcription Factors / metabolism*
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Two-Hybrid System Techniques
Substances
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Cell Adhesion Molecules
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Cytoskeletal Proteins
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Fblim1 protein, mouse
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Homeobox Protein Nkx-2.5
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Homeodomain Proteins
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LIM Domain Proteins
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Macromolecular Substances
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NKX2-5 protein, human
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Recombinant Fusion Proteins
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Trans-Activators
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Transcription Factors
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Atrial Natriuretic Factor
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Calcium