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 beta (A beta)-induced vascular dysfunction significantly contributes to the pathogenesis of Alzheimer's disease (AD). A beta is known to impair endothelial nitric oxide synthase (eNOS) activity, thus inhibiting endothelial nitric oxide production (NO). Method: In this study, we investigated A beta-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 A beta 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, A beta stimulated the production of reactive oxygen species in endothelial cells and concomitant treatments of the cells with the antioxidant N-acetyl-cysteine (NAC) prevented A beta 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 A beta results in altered interaction of HSP90 with Akt and eNOS, therefore promoting vascular dysfunction. This mechanism, by contributing to A beta-mediated blockade of nitric oxide production, may significantly contribute to the cognitive impairment seen in AD patients.