Cellular signaling and NO production.
The endothelium can evoke relaxations (dilatations) of the underlying vascular smooth muscle, by releasing vasodilator substances. The best characterized endothelium-derived relaxing factor is nitric oxide (NO), which is synthesized by the endothelial isoform of nitric oxide synthase (eNOS). Endothelium-dependent relaxations involve both pertussis-toxin-sensitive G(i) (e.g., responses to serotonin, sphingosine 1-phosphate, alpha(2)-adrenergic agonists, and thrombin) and pertussis-toxin-insensitive G(q) (e.g., adenosine diphosphate and bradykinin) coupling proteins. eNOS undergoes a complex pattern of intracellular regulation, including post-translational modifications involving enzyme acylation and phosphorylation. eNOS is reversibly targeted to signal-transducing plasmalemmal caveolae where the enzyme interacts with a number of regulatory proteins, many of which are modified in cardiovascular disease states. The release of nitric oxide by the endothelial cell can be up- (e.g., by estrogens, exercise, and dietary factors) and down-regulated (e.g. oxidative stress, smoking, and oxidized low-density lipoproteins). It is reduced in the course of vascular disease (e.g., diabetes and hypertension). Arteries covered with regenerated endothelium (e.g. following angioplasty) selectively lose the pertussis-toxin-sensitive pathway for NO release which favors vasospasm, thrombosis, penetration of macrophages, cellular growth, and the inflammatory reaction leading to atherosclerosis. The unraveling of the complex interaction of the pathways regulating the presence and the activity of eNOS will enhance the understanding of the perturbations in endothelium-dependent signaling that are seen in cardiovascular disease states, and may lead to the identification of novel targets for therapeutic intervention.
Michel
Thomas
T
Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA. thomas_michel@harvard.edu
Vanhoutte
Paul M
PM
D000215:Acylation; D048868:Adaptor Proteins, Signal Transducing; D000375:Aging / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism; D002352:Carrier Proteins / Q000502:physiology; D022461:Caveolins / Q000378:metabolism; D003327:Coronary Disease / Q000503:physiopathology; D004268:DNA-Binding Proteins; D015536:Down-Regulation; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic; D018841:HSP90 Heat-Shock Proteins / Q000502:physiology; D006801:Humans; D006937:Hypercholesterolemia / Q000503:physiopathology; D006973:Hypertension / Q000503:physiopathology; D047908:Intracellular Signaling Peptides and Proteins / Q000502:physiology; D008077:Lipoproteins, LDL; D009569:Nitric Oxide / Q000502:physiology*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D010766:Phosphorylation; D025941:Protein Interaction Mapping; D011499:Protein Processing, Post-Translational; D012038:Regeneration; D015398:Signal Transduction; D044767:Ubiquitin-Protein Ligases; D015854:Up-Regulation
D048868:Adaptor Proteins, Signal Transducing; D002147:Calmodulin; D002352:Carrier Proteins; D022461:Caveolins; D004268:DNA-Binding Proteins; D018841:HSP90 Heat-Shock Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008077:Lipoproteins, LDL; C470345:NOSTRIN protein, human; C099252:oxidized low density lipoprotein; D009569:Nitric Oxide; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; C419706:NOSIP protein, human; D044767:Ubiquitin-Protein Ligases; D002118:Calcium