Identification of the functional domain in the transcription factor RTEF-1 that mediates alpha 1-adrenergic signaling in hypertrophied cardiac myocytes

• Published in: The Journal of biological chemistry 2000-06, Vol.275 (23), p.17476
• Main Authors: Ueyama, T, Zhu, C, Valenzuela, Y M, Suzow, J G, Stewart, A F
• Format: Article
• Language: English
• Subjects: Actins - genetics; Amino Acid Sequence; Animals; Animals, Newborn; Cardiomegaly - physiopathology; Cells, Cultured; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Genes, Reporter; Heart - physiology; Heart - physiopathology; Mice; Molecular Sequence Data; Muscle Proteins - chemistry; Muscle Proteins - genetics; Muscle Proteins - metabolism; Mutagenesis, Site-Directed; Myocardium - cytology; Myocardium - metabolism; Nuclear Proteins - metabolism; Phosphorylation; Rats; Receptors, Adrenergic, alpha-1 - physiology; Recombinant Fusion Proteins - metabolism; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; Sequence Alignment; Signal Transduction; Trans-Activators - chemistry; Trans-Activators - genetics; Trans-Activators - metabolism; Transcription Factors - genetics; Transcription Factors - metabolism; Transfection
• ISSN: 0021-9258

Cardiac myocytes respond to alpha(1)-adrenergic receptor stimulation by a progressive hypertrophy accompanied by the activation of many fetal genes, including skeletal muscle alpha-actin. The skeletal muscle alpha-actin gene is activated by signaling through an MCAT element, the binding site of the transcription enhancer factor-1 (TEF-1) family of transcription factors. Previously, we showed that overexpression of the TEF-1-related factor (RTEF-1) increased the alpha(1)-adrenergic response of the skeletal muscle alpha-actin promoter, whereas TEF-1 overexpression did not. Here, we identified the functional domains and specific sequences in RTEF-1 that mediate the alpha(1)-adrenergic response. Chimeric TEF-1 and RTEF-1 expression constructs localized the region responsible for the alpha(1)-adrenergic response to the carboxyl-terminal domain of RTEF-1. Site-directed mutagenesis was used to inactivate eight serine residues of RTEF-1, not present in TEF-1, that are putative targets of alpha(1)-adrenergic-dependent kinases. Mutation of a single serine residue, Ser-322, reduced the alpha(1)-adrenergic activation of RTEF-1 by 70% without affecting protein stability, suggesting that phosphorylation at this serine residue accounts for most of the alpha(1)-adrenergic response. Thus, these results demonstrate that RTEF-1 is a direct target of alpha(1)-adrenergic signaling in hypertrophied cardiac myocytes.