title: Equol-stimulated mitochondrial reactive oxygen species activate endothelial nitric oxide synthase and redox signaling in endothelial cells: roles for F-actin and GPR30.
abstract: We reported previously that dietary isoflavones modulate arterial blood pressure in vivo and that the daidzein metabolite equol rapidly activates endothelial NO synthase (eNOS) via Akt and extracellular signal-regulated kinase 1/2-dependent signaling. In this study, we report the first evidence in human endothelial cells that acute stimulation of mitochondrial superoxide generation by equol (100 nmol/L) is required for eNOS activation. Scavengers of superoxide (superoxide dismutase and manganese [III] tetrakis[1-methyl-4-pyridyl]porphyrin) abrogated equol stimulated Akt and eNOS phosphorylation, and the mitochondrial complex I inhibitor rotenone inhibited Akt, extracellular signal-regulated kinase 1/2, and eNOS phosphorylation, as well as NO-mediated increases in intracellular cGMP. Equol also induced rapid alterations in F-actin fiber distribution, with depolymerization of F-actin with cytochalasin D abrogating equol-stimulated mitochondrial superoxide generation. Treatment of cells with pertussis toxin or inhibition of GPR30/epidermal growth factor receptor kinase transactivation prevented equol-induced activation of extracellular signal-regulated kinase 1/2 via c-Src, Akt, and eNOS. Moreover, inhibition of epidermal growth factor receptor kinase activation with AG-1478 abrogated equol-stimulated mitochondrial reactive oxygen species generation and subsequent kinase and eNOS activation. Our findings suggest that equol-stimulated mitochondrial reactive oxygen species modulate endothelial redox signaling and NO release involving transactivation of epidermal growth factor receptor kinase and reorganization of the F-actin cytoskeleton. Identification of these novel actions of equol may provide valuable insights for therapeutic strategies to restore endothelial function in cardiovascular disease.
authors.affiliation: Cardiovascular Division, British Heart Foundation Centre for Research Excellence, School of Medicine, Franklin-Wilkins Building (Room 3.01), King's College London, 150 Stamford St, London SE1 9NH, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Rowlands
authors.forename: Sarah
authors.initials: S
authors.lastname: Chapple
authors.forename: Richard C M
authors.initials: RC
authors.lastname: Siow
authors.forename: Giovanni E
authors.initials: GE
authors.lastname: Mann
mesh_terms: D000199:Actins / Q000378:metabolism*; D000704:Analysis of Variance; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D060754:Equol; D066246:ErbB Receptors / Q000378:metabolism; D006801:Humans; D007529:Isoflavones / Q000494:pharmacology*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D010084:Oxidation-Reduction / Q000187:drug effects; D048789:Phytoestrogens / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D011960:Receptors, Estrogen; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D014471:Umbilical Veins / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
chemical_list: C007610:4',7-dihydroxy-3,4-dihydroisoflavone; D000199:Actins; C109584:GPER1 protein, human; D007529:Isoflavones; D048789:Phytoestrogens; D017382:Reactive Oxygen Species; D011960:Receptors, Estrogen; D043562:Receptors, G-Protein-Coupled; D060754:Equol; D052250:Nitric Oxide Synthase Type III; D066246:ErbB Receptors