The alpha1D-adrenergic receptor induces vascular smooth muscle apoptosis via a p53-dependent mechanism.
Activation of the endogenous alpha1-adrenergic receptor (AR) associated with human aortic smooth muscle cells resulted in a dose- and time-dependent increase in the levels of mitochondrial reactive oxygen species (ROS). ROS increases were apparent within 10 min and maximal after 45 min. Prolonged activation (>4 h) of the alpha1-AR resulted in smooth muscle cell apoptosis. Both the increase in ROS and apoptotic cell death were blocked by the nonselective alpha1-AR antagonist prazosin as well as the selective alpha1D-AR antagonist 8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4.5]decane-7, 9-dione (BMY 7378). Increases in ROS and apoptosis produced by alpha1-AR activation were also blocked by the p38 mitogen-activated protein kinase inhibitor 4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)-1H-imidazole (SB 202190) and the NAPDH oxidase inhibitor apocynin. The extracellular signal-regulated kinase 1/2 inhibitor 2'-amino-3'-methoxyflavone (PD 98059) or the c-Jun NH2-terminal kinase inhibitor 1, 9-pyrazoloanthrone anthra(1, 9-cd)pyrazol-6(2H)-one (SP 600125) was without effect on increases in ROS levels or apoptosis. Pifithrin-alpha, an inhibitor of the tumor suppressor protein p53, had no effect on ROS generation but did block alpha1D-AR-induced apoptosis. Activation of the alpha1D-AR resulted in translocation of p53 to the mitochondria. The mitochondrial translocation of p53 was blocked by prazosin, BMY 7378, apocynin, SB 202190, and pifithrin-alpha. Apoptosis was also blocked by small interfering RNA directed against p53. These data show that the alpha1D-AR is coupled to the generation of mitochondrial ROS by a pathway involving p38 and NADPH oxidase. Sustained activation of the alpha1D-AR results in smooth muscle cell apoptosis in a pathway that involves the tumor suppressor protein p53 and the mitochondrial translocation of p53. The data also provide evidence of a linkage between the alpha1D-AR and p53.
García-Cazarín
Mary L
ML
Department of Molecular and Biomedical Pharmacology, The University of Kentucky College of Medicine, 800 Rose St., UKMC MS 305, Lexington, KY 40536-0084, USA.
Smith
Jennifer L
JL
Clair
Daret K St
DK
Piascik
Michael T
MT
D000098:Acetophenones / Q000494:pharmacology; D058668:Adrenergic alpha-1 Receptor Antagonists; D000873:Anthracenes / Q000494:pharmacology; D001011:Aorta / Q000166:cytology / Q000378:metabolism*; D017209:Apoptosis; D052160:Benzothiazoles / Q000494:pharmacology; D002478:Cells, Cultured; D016895:Culture Media, Serum-Free; D004146:Dioxanes / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D008928:Mitochondria / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D010656:Phenylephrine / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D018340:Receptors, Adrenergic, alpha-1 / Q000502:physiology*; D013997:Time Factors; D014050:Toluene / Q000031:analogs & derivatives / Q000494:pharmacology; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors / Q000502:physiology*
D000098:Acetophenones; D058668:Adrenergic alpha-1 Receptor Antagonists; D000873:Anthracenes; D052160:Benzothiazoles; D016895:Culture Media, Serum-Free; D004146:Dioxanes; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007093:Imidazoles; D010879:Piperazines; D011725:Pyridines; D017382:Reactive Oxygen Species; D018340:Receptors, Adrenergic, alpha-1; D016159:Tumor Suppressor Protein p53; C057446:5-methylurapidil; C432165:pyrazolanthrone; D010656:Phenylephrine; D014050:Toluene; C056165:acetovanillone; C121565:pifithrin; C010654:(2-(2',6'-dimethoxy)phenoxyethylamino)methylbenzo-1,4-dioxane; C053428:BMY 7378; C090942:4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)imidazole; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D011224:Prazosin