Amyloid β peptide-induced inhibition of endothelial nitric oxide production involves oxidative stress-mediated constitutive eNOS/HSP90 interaction and disruption of agonist-mediated Akt activation.
BACKGROUND
Amyloid β (Aβ)-induced vascular dysfunction significantly contributes to the pathogenesis of Alzheimer's disease (AD). Aβ is known to impair endothelial nitric oxide synthase (eNOS) activity, thus inhibiting endothelial nitric oxide production (NO).


METHODS
In this study, we investigated Aβ-effects on heat shock protein 90 (HSP90) interaction with eNOS and Akt in cultured vascular endothelial cells and also explored the role of oxidative stress in this process.


RESULTS
Treatments of endothelial cells (EC) with Aβ promoted the constitutive association of HSP90 with eNOS but abrogated agonist (vascular endothelial growth factor (VEGF))-mediated HSP90 interaction with Akt. This effect resulted in blockade of agonist-mediated phosphorylation of Akt and eNOS at serine 1179. Furthermore, Aβ stimulated the production of reactive oxygen species in endothelial cells and concomitant treatments of the cells with the antioxidant N-acetyl-cysteine (NAC) prevented Aβ effects in promoting HSP90/eNOS interaction and rescued agonist-mediated Akt and eNOS phosphorylation.


CONCLUSIONS
The obtained data support the hypothesis that oxidative damage caused by Aβ results in altered interaction of HSP90 with Akt and eNOS, therefore promoting vascular dysfunction. This mechanism, by contributing to Aβ-mediated blockade of nitric oxide production, may significantly contribute to the cognitive impairment seen in AD patients.
Department of Ophthalmology, Georgia Regents University, Health Sciences Campus, 1120 15th St., Augusta, GA, 30912, USA. flamoke@gru.edu.
Folami
F
Lamoke
Department of Biology, University of Rome 'Roma Tre', Via Ostiense, 169, Rome, 00154, Italy. irc-fsh@hotmail.it.
Valeria
V
Mazzone
Department of Biology, University of Rome 'Roma Tre', Via Ostiense, 169, Rome, 00154, Italy. tiziana.persichini@uniroma3.it.
Tiziana
T
Persichini
Department of Neurology and Laboratory of Neuroscience, IRCCS Istituto Auxologico Italiano, Cusano Milanino 20095, Milan, Italy. mollace@hotmail.it.
Annamaria
A
Maraschi
Department of Kinesiology, College of William and Mary, 200 Stadium Dr., Williamsburg, VA, 23186, USA. mbharr@wm.edu.
Michael Brennan
MB
Harris
Vascular Biology Center, Georgia Regents University, 1120 15th St., Augusta, GA, 30912, USA. rvenema@gru.edu.
Richard C
RC
Venema
Department of Biology, University of Rome 'Roma Tre', Via Ostiense, 169, Rome, 00154, Italy. marco.colasanti@uniroma3.it.
Marco
M
Colasanti
IRC-FSH, Department of Health Sciences, University of Catanzaro 'Magna Graecia', Catanzaro Complesso 'Ninì Barbieri', Roccelletta di Borgia, 88021, Italy. micaela.gliozzi@gmail.com.
Micaela
M
Gliozzi
IRC-FSH, Department of Health Sciences, University of Catanzaro 'Magna Graecia', Catanzaro Complesso 'Ninì Barbieri', Roccelletta di Borgia, 88021, Italy. muscoli@unicz.it.|IRCCS San Raffaele Pisana, Via di Val Cannuta, 247, 00166, Rome, Italy. muscoli@unicz.it.
Carolina
C
Muscoli
Department of Ophthalmology, Georgia Regents University, Health Sciences Campus, 1120 15th St., Augusta, GA, 30912, USA. mbartoli@gru.edu.
Manuela
M
Bartoli
IRC-FSH, Department of Health Sciences, University of Catanzaro 'Magna Graecia', Catanzaro Complesso 'Ninì Barbieri', Roccelletta di Borgia, 88021, Italy. mollace@libero.it.|IRCCS San Raffaele Pisana, Via di Val Cannuta, 247, 00166, Rome, Italy. mollace@libero.it.
Vincenzo
V
Mollace
D000111:Acetylcysteine / Q000494:pharmacology; D016229:Amyloid beta-Peptides / Q000494:pharmacology*; D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D042783:Endothelial Cells; D004730:Endothelium, Vascular / Q000166:cytology; D016166:Free Radical Scavengers / Q000494:pharmacology; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism*; D047468:Immunoprecipitation; D009569:Nitric Oxide / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects*; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology
D016229:Amyloid beta-Peptides; D016166:Free Radical Scavengers; D018841:HSP90 Heat-Shock Proteins; D042461:Vascular Endothelial Growth Factor A; D009569:Nitric Oxide; D012694:Serine; D052250:Nitric Oxide Synthase Type III; D051057:Proto-Oncogene Proteins c-akt; D000111:Acetylcysteine