Protein kinase-A dependent phosphorylation of transcription enhancer factor-1 represses its DNA-binding activity but enhances its gene activation ability.
The cAMP-dependent signaling pathway has been implicated in cardiac cell growth/differentiation and muscle gene transcription. Previously, we have identified a cAMP-inducible E-box/M-CAT hybrid motif in the cardiac alpha-myosin heavy chain (alpha-MHC) gene promoter. The two factors, TEF-1 and Max, that bind to this motif are found to physically associate with each other and exert a positive cooperative effect for gene regulation. Here we show that TEF-1, but not Max, is a substrate for protein kinase-A (PK-A)-dependent phosphorylation. TEF-1 is phosphorylated by PK-A at residue serine-102. This post-translational modification of TEF-1 repressed its DNA-binding activity, but not its ability to interact with the Max protein. Replacement of serine-102 in TEF-1 by a neutral or a charged amino acid did not abolish its DNA-binding ability, suggesting that changing a charge at the 102 amino-acid position of TEF-1 was not sufficient to inhibit its DNA-binding activity. We also show that PK-A response of the alpha-MHC gene is stimulated by the presence of wild-type TEF-1 but not by mutant TEF-1 having serine-102 replaced by alanine, suggesting that phosphorylation at this residue accounts for the cAMP/PK-A response of the gene. Thus, these data demonstrate that TEF-1 is a direct target of cAMP/PK-A signaling in cardiac myocytes.
Department of Surgery (Cardiac and Thoracic), The University of Chicago, 5841 South Maryland Avenue, Chicago, IL 60637, USA. mgupta@surgery.bsd.uchicago.edu
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D050976:Basic-Leucine Zipper Transcription Factors; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005333:Fetus; D005786:Gene Expression Regulation; D005982:Glutathione Transferase / Q000235:genetics; D006801:Humans; D007700:Kinetics; D051379:Mice; D008969:Molecular Sequence Data; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D009687:Nuclear Proteins; D010766:Phosphorylation; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000737:chemistry; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012694:Serine / Q000378:metabolism; D000091262:TEA Domain Transcription Factors; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D014162:Transfection
D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; C499330:MAX protein, human; C499329:Max protein, rat; C067850:Myc associated factor X; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D000091262:TEA Domain Transcription Factors; C057182:TEAD1 protein, human; D014157:Transcription Factors; C068422:Max protein, mouse; D012694:Serine; D005982:Glutathione Transferase; D017868:Cyclic AMP-Dependent Protein Kinases