title: Activation of signal transducers and activators of transcription by alpha(1A)-adrenergic receptor stimulation in PC12 cells.
abstract: In PC12 cells stably expressing alpha(1A)-adrenergic receptors (ARs), norepinephrine (NE) activates several mitogen-activated protein kinase pathways and causes differentiation (). Using retroviral luciferase reporters, we found that NE also activated both signal transducers and activators of transcription (Stat) and gamma-interferon-activated sequence-mediated transcriptional responses, with maximal effects similar to those caused by interleukin-6 (IL-6). UTP and epidermal growth factor had no effect, whereas nerve growth factor caused a small Stat activation. Responses to NE were blocked by prazosin and depended on receptor density. Responses to NE were not blocked by inhibitors of mitogen-activated protein kinase kinase (PD98059), protein kinase C (GFX203290), Src (PP2), Jak2 (AG490), or the calcium chelator 1, 2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid. The p38 mitogen-activated protein kinase inhibitors SB202190 and SB203580 blocked Stat activation by NE, the epidermal growth factor receptor inhibitor AG1478 caused a small inhibition, but the phosphoinositide 3 kinase inhibitor LY294002 potentiated both responses. Gel shifts confirmed formation of nuclear factors binding to both Stat and gamma-interferon-activated sequence consensus sequences in response to NE and IL-6. Immunoprecipitation experiments showed that IL-6 increased tyrosine phosphorylation of Stat1 and Stat3 in PC12 cells, whereas NE caused a sustained increase in tyrosine phosphorylation of Stat1. These results suggest that alpha(1A)-AR stimulation causes Stat-mediated transcriptional responses in PC12 cells that are not downstream of known second messenger or tyrosine kinase pathways.
authors.affiliation: Department of Pharmacology, Emory University, Atlanta, GA, USA.
authors.forename: H
authors.initials: H
authors.lastname: Zhong
authors.forename: T J
authors.initials: TJ
authors.lastname: Murphy
authors.forename: K P
authors.initials: KP
authors.lastname: Minneman
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D017930:Genes, Reporter; D006133:Growth Substances / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D008156:Luciferases / Q000096:biosynthesis / Q000235:genetics; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009638:Norepinephrine / Q000502:physiology; D016716:PC12 Cells; D010766:Phosphorylation; D051381:Rats; D018340:Receptors, Adrenergic, alpha-1 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D015533:Transcriptional Activation; D014162:Transfection; D014443:Tyrosine / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D006133:Growth Substances; D015850:Interleukin-6; D018340:Receptors, Adrenergic, alpha-1; D014443:Tyrosine; D008156:Luciferases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D009638:Norepinephrine