?1 ADRENERGIC RECEPTOR ACTIVATION & EXPRESSION

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The ?-adrenergic receptors (?-ARs) are important modulators in the sympathetic control of various metabolic processes in the central (CNS) and peripheral nervous system. These receptors are localized at multiple sites throughout the nervous system, and serve as important regulators of CNS-mediated behavior and several neural functions, including mood, memory, neuroendocrine control, and stimulation of autonomic function. My laboratory has cloned, sequenced, and expressed the rat and rhesus macaque ?1-adrenergic receptor genes. We have defined the ?1-AR transcriptional start sites, promoter elements, and polyadenylation sites used for expression in the C6 glioma cell line, and have identified potential enhancer and repressor regions that influence ?1-AR expression. We have demonstrated that the inducible cAMP early repressor (ICER) is induced in C6 cells by ?1-AR agonists, and that ICER interacts with the ?1-AR promoter to down-regulate ?1-AR mRNA transcription, w ith resul tant diminution of cell surface receptor. We have also shown that the rat ?1-AR mRNA contains two functional polyadenylation sites, and that transcript selection occurs in C6 cells undergoing isoproterenol-induced ?1-AR mRNA down-regulation. This process may be regulated by post-transcriptional control mechanisms, potentially with the use of RNA stability proteins interacting with an AU-rich ?1-AR 3' untranslated region. Current research is centered on identifying genomic elements and trans-activators of ?1-AR transcription, with the use of ?1-AR luciferase-reporter recombinants, transfection assays, DNA mobility shift and DNase footprinting assays. The overall focus of this project is to precisely identify functional regulatory elements and factors involved in the regulation of the ?1-adrenergic receptor gene, and to analyze the transcriptional activation of the ?1-adrenergic receptor subtype during receptor down-regulation and hormonal stimulation. Research will initially utiliz e rodent tissues, prior to the use of nonhuman primate tissues, in the identification of ?1-AR transactivators. FUNDING NIH HL42358, and American Heart Association Established Investigator Award PUBLICATIONS Li Z, Vaidya RVA, Alvaro JD, Iredale PA, Hsu R, Hoffman G, Fitzgerald L, Curran PK, Machida CA, Fishman PH, Duman RS. Protein kinase C-mediated down-regulation of ?1-AR gene expression in rat C6 glioma cells. Mol Pharmacol 54:14-21, 1998. Yang YF, Kirigiti P, Li B, Deshmane S, Machida CA. Differential selection of ?1-adrenergic receptor transcripts during agonist-induced down-regulation. Soc Neurosci Abstr 24:600, 1998 (abstract 237.20).