title: Signaling pathways activated by alpha1-adrenergic receptor subtypes in PC12 cells.
abstract: PC12 cells were used to compare signaling pathways activated by alpha1-adrenergic receptor (AR) subtypes. PC12 cells were transfected with human alpha1A, alpha1B, or alpha1D-ARs, and subclones stably expressing receptor densities in physiological ranges isolated and characterized. Norepinephrine (NE) activated a large number of signaling pathways in transfected cells, including inositol phosphate formation, intracellular calcium, all three arms of the mitogen activated protein kinase pathways, and a number of tyrosine kinases. Activation of mitogen activated protein kinase pathways and tyrosine kinases was not blocked by chelation of intracellular calcium with BAPTA or inhibition of protein kinase C. NE also activated luciferase reporter constructs for seven different transcription factors (AP1, SRE, CRE, NFkappaB, NFAT, Stat, GAS) following transfection into alpha1A-AR expressing PC12 cells. However, similar increases in inositol phosphate formation and intracellular Ca2+ caused by purinergic P2Y2 receptor activation did not activate any of these reporters. Comparison of alpha1-AR subtypes showed that the alpha1A activated all seven reporters, the alpha1B showed smaller effects, while the alpha1D was ineffective. NE caused differentiation of alpha1A, but not alpha1B or alpha1D, -AR expressing PC12 cells similar to that caused by NGF. This NE-induced differentiation was reduced or blocked by all inhibitors tested. We conclude that alpha1-ARs activate many signaling pathways and transcriptional responses in PC12 cells, which are not linearly related to second messenger production, and which may differ for different alpha1-AR subtypes.
authors.affiliation: Department of Pharmacology, Emory University, Atlanta, GA 30322, USA.
authors.forename: H
authors.initials: H
authors.lastname: Zhong
authors.forename: D
authors.initials: D
authors.lastname: Lee
authors.forename: A
authors.initials: A
authors.lastname: Robeva
authors.forename: K P
authors.initials: KP
authors.lastname: Minneman
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D017930:Genes, Reporter / Q000187:drug effects; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D007295:Inositol Phosphates / Q000096:biosynthesis; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D009638:Norepinephrine / Q000494:pharmacology; D016716:PC12 Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D018340:Receptors, Adrenergic, alpha-1 / Q000145:classification* / Q000378:metabolism*; D015398:Signal Transduction; D013997:Time Factors; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D004791:Enzyme Inhibitors; D005419:Flavonoids; D007093:Imidazoles; D007295:Inositol Phosphates; D011725:Pyridines; D018340:Receptors, Adrenergic, alpha-1; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C; D020929:Mitogen-Activated Protein Kinase Kinases; C090942:4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)imidazole; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D002118:Calcium; D009638:Norepinephrine