Genistein acutely stimulates nitric oxide synthesis in vascular endothelial cells by a cyclic adenosine 5'-monophosphate-dependent mechanism.
Genistein may improve vascular function, but the mechanism of this effect is unclear. We tested the hypothesis that genistein directly regulates vascular function through stimulation of endothelial nitric oxide synthesis. Genistein activated endothelial nitric oxide synthase (eNOS) in intact bovine aortic endothelial cells and human umbilical vein endothelial cells over an incubation period of 10 min. The maximal eNOS activity was at 1 microm genistein. Consistent with this activation pattern, 1 microm genistein maximally stimulated the phosphorylation of eNOS at serine 1179 at 10 min of incubation. The rapid activation of eNOS by genistein was not dependent on RNA transcription or new protein synthesis and was not blocked by a specific estrogen receptor antagonist. In addition, inhibition of MAPK or phosphatidylinositol 3-OH kinase/Akt kinase had no affect on eNOS activation by genistein. Furthermore, the genistein effect on eNOS was also independent of tyrosine kinase inhibition. However, inhibition of cAMP-dependent kinase [protein kinase A (PKA)] by H89 completely abolished the genistein-stimulated eNOS activation and phosphorylation, suggesting that genistein acted through a PKA-dependent pathway. These findings demonstrated that genistein had direct nongenomic effects on eNOS activity in vascular endothelial cells, leading to eNOS activation and nitric oxide synthesis. These effects were mediated by PKA and were unrelated to an estrogenic effect. This cellular mechanism may underlie some of the cardiovascular protective effects proposed for soy phytoestrogens.
Liu
Dongmin
D
Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa and Veterans Affairs Medical Center, Iowa City, Iowa 52246, USA.
Homan
Laurie L
LL
Dillon
Joseph S
JS
D000818:Animals; D001011:Aorta / Q000166:cytology; D002417:Cattle; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D019833:Genistein / Q000494:pharmacology*; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D014471:Umbilical Veins / Q000166:cytology
D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D004791:Enzyme Inhibitors; D048049:Extracellular Signal-Regulated MAP Kinases; D019833:Genistein; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; C496314:NOS3 protein, human; C494918:AKT1 protein, human