title: Cell-signaling evidence for adenosine stimulation of coronary smooth muscle proliferation via the A1 adenosine receptor.
abstract: For decades, it has been thought that adenosine is exclusively antimitogenic on vascular smooth muscles via the A2-type adenosine receptor. Recently, we have demonstrated that adenosine stimulates proliferation of porcine coronary artery smooth muscle cells (CASMC) through the A1 adenosine receptor. However, the cell-signaling mechanisms underlying A1 receptor-mediated CASMC proliferation in response to adenosine have not been defined. Here, we show that in cultured CASMC, adenosine stimulates phosphorylation of extracellular signal-regulated kinase (ERK), Jun N-terminal kinase (JNK), and AKT in a concentration- and time-dependent manner. This effect is fully mimicked by NECA (nonselective agonist), largely mimicked by CCPA (A1-selective agonist), weakly mimicked by 2-Cl-IB-MECA (A3-selective agonist), but not by CGS21680 (A2A-selective agonist), indicating that adenosine signals strongly via the A1 receptor to these mitogenic signaling pathways. This interpretation is supported by the finding that adenosine- and CCPA-induced phosphorylation of ERK, JNK, and AKT are inhibited by pertussis toxin (inactivator of Gi proteins) and by DPCPX (A1-selective antagonist), but not by SCH58261, MRS1706, and VUF5574 (A2A-, A2B-, and A3-selective antagonists, respectively). In addition, adenosine- and CCPA-induced phosphorylation of ERK, JNK, and AKT is inhibited, respectively, by U0126, PD98059 (mitogen-activated protein kinase kinase inhibitors), SP600125 (JNK kinase inhibitor), and wortmannin (phosphatidylinositol 3-kinase inhibitor). Furthermore, these kinase inhibitors abolish or diminish adenosine- and CCPA-induced increases in the rate of cellular DNA synthesis, bromodeoxyuridine incorporation, protein synthesis, and cell number. We conclude that adenosine activates the ERK, JNK, and phosphatidylinositol 3-kinase/AKT pathways primarily through the A1 receptor, leading to CASMC mitogenesis.
authors.affiliation: Department of Medical Pharmacology and Physiology, University of Missouri-Columbia, School of Medicine, Columbia, MO 65212, USA.
authors.forename: Jianzhong
authors.initials: J
authors.lastname: Shen
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Halenda
authors.forename: Michael
authors.initials: M
authors.lastname: Sturek
authors.forename: Peter A
authors.initials: PA
authors.lastname: Wilden
mesh_terms: D000241:Adenosine / Q000494:pharmacology*; D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000166:cytology / Q000187:drug effects*; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D043682:Receptor, Adenosine A1 / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D013552:Swine; D014970:Xanthines / Q000494:pharmacology
chemical_list: D000241:Adenosine; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D047428:Protein Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D043682:Receptor, Adenosine A1; D014970:Xanthines; C051360:1,3-dipropyl-8-cyclopentylxanthine