Abstract
Nuclear retinoic acid receptors (RARs) are ligand-dependent transcription factors that regulate the expression of retinoic acid target genes. Although the importance of RAR phosphorylation in their N-terminal domain is clearly established, the underlying mechanism for the phosphorylation-dependent transcriptional activity of the receptors had not been elucidated yet. Here, using a yeast two-hybrid system, we report the isolation of vinexin beta as a new cofactor that interacts with the N-terminal A/B domain of the RARgamma isotype. Vinexin beta is a multiple SH3 motif-containing protein associated with the cytoskeleton and also present in the nucleus. We demonstrate that vinexin beta colocalizes with RARgamma in the nucleus and interacts with the non-phosphorylated form of the AF-1 domain of RARgamma. We also show that this interaction is prevented upon phosphorylation of the AF-1 domain. Using F9 cells stably overexpressing vinexin beta or vinexin knockdown by RNA interference, we demonstrate that vinexin beta is an inhibitor of RARgamma-mediated transcription. We propose a model in which phosphorylation of the AF-1 domain controls RARgamma-mediated transcription through triggering the dissociation of vinexin beta.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adaptor Proteins, Signal Transducing / chemistry
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Adaptor Proteins, Signal Transducing / metabolism*
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Amino Acid Motifs
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Amino Acid Sequence
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Animals
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COS Cells
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Cell Nucleus / metabolism
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Chloramphenicol O-Acetyltransferase / metabolism
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Cloning, Molecular
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DNA, Complementary / metabolism
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Glutathione Transferase / metabolism
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Humans
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Immunoprecipitation
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Mice
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Microscopy, Fluorescence
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Molecular Sequence Data
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Muscle Proteins / chemistry
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Muscle Proteins / metabolism*
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Phosphorylation
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Plasmids / metabolism
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Protein Binding
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Protein Structure, Tertiary
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RNA / metabolism
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RNA Interference
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RNA, Small Interfering / metabolism
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Receptors, Retinoic Acid / chemistry*
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Retinoic Acid Receptor gamma
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Reverse Transcriptase Polymerase Chain Reaction
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Sequence Homology, Amino Acid
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Time Factors
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Transcription, Genetic*
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Transcriptional Activation
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Transfection
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Tretinoin / metabolism
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Two-Hybrid System Techniques
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beta-Galactosidase / metabolism
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src Homology Domains
Substances
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Adaptor Proteins, Signal Transducing
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DNA, Complementary
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Muscle Proteins
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RNA, Small Interfering
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Receptors, Retinoic Acid
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SORBS3 protein, human
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Sorbs3 protein, mouse
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Tretinoin
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RNA
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Chloramphenicol O-Acetyltransferase
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Glutathione Transferase
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beta-Galactosidase