Vgl-4, a novel member of the vestigial-like family of transcription cofactors, regulates alpha1-adrenergic activation of gene expression in cardiac myocytes.
Cardiac and skeletal muscle genes are regulated by the transcriptional enhancer factor (TEF-1) family of transcription factors. In skeletal muscle, TEF-1 factors interact with a skeletal muscle-specific cofactor called Vestigial-like 2 (Vgl-2) that is related to the Drosophila protein Vestigial. Here, we characterize Vgl-4, the only member of the Vestigial-like family expressed in the heart. Unlike other members of the Vgl family that have a single TEF-1 interaction domain called the tondu (TDU) motif, Vgl-4 has two TDU motifs in its carboxyl-terminal domain. Like other Vgl factors, Vgl-4 physically interacts with TEF-1 in an immunoprecipitation assay. Vgl-4 functionally interacts with TEF-1 and also with myocyte enhancer factor 2 in a mammalian two-hybrid assay. Overexpression of Vgl-4 in cardiac myocytes interfered with the basal expression and alpha1-adrenergic receptor-dependent activation of a TEF-1-dependent skeletal alpha-actin promoter. In cardiac myocytes cultured in serum and in serum-free medium, a myc-tagged Vgl-4 protein was located in the nucleus and cytoplasm but was exported from the nucleus when cells were treated with alpha1-adrenergic receptor agonist. A chimeric nuclear-retained Vgl-4 protein inhibited alpha1-adrenergic receptor-dependent activation. In contrast, deletion of the TDU motifs of Vgl-4 prevented Vgl-4 nuclear localization, relieved Vgl-4 interference of basal activity, and enhanced alpha1-adrenergic up-regulation of the skeletal alpha-actin promoter. Nuclear export of Vgl-4 is dependent on the nuclear exportin CRM-1. These results suggest that Vgl-4 modulates the activity of TEF-1 factors and counteracts alpha1-adrenergic activation of gene expression in cardiac myocytes.
Chen
Hsiao-Huei
HH
Cardiovascular Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA.
Mullett
Steven J
SJ
Stewart
Alexandre F R
AF
D000199:Actins / Q000378:metabolism; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D004247:DNA / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009124:Muscle Proteins; D009154:Mutation; D009206:Myocardium / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D018340:Receptors, Adrenergic, alpha-1 / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D000091262:TEA Domain Transcription Factors; D014018:Tissue Distribution; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D014162:Transfection; D020798:Two-Hybrid System Techniques
D000199:Actins; D004268:DNA-Binding Proteins; D009124:Muscle Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D018340:Receptors, Adrenergic, alpha-1; D011993:Recombinant Fusion Proteins; D000091262:TEA Domain Transcription Factors; C057182:TEAD1 protein, human; D014157:Transcription Factors; C470573:VGLL2 protein, human; C488533:VGLL4 protein, human; C488534:vestigial-like 4 protein, mouse; D004247:DNA