HSV-1 promotes Ca2+-mediated APP phosphorylation and Aβ accumulation in rat cortical neurons

Epidemiological and experimental findings suggest that chronic infection with Herpes simplex virus type 1 (HSV-1) may be a risk factor for Alzheimer's disease (AD), but the molecular mechanisms underlying this association have not been fully identified. We investigated the effects of HSV-1 on excitability and intracellular calcium signaling in rat cortical neurons and the impact of these effects on amyloid precursor protein (APP) processing and the production of amyloid-beta peptide (A beta). Membrane depolarization triggering firing rate increases was observed shortly after neurons were challenged with HSV-1 and was still evident 12 hours postinfection. These effects depended on persistent sodium current activation and potassium current inhibition. The virally induced hyperexcitability triggered intracellular Ca2+ signals that significantly increased intraneuronal Ca2+ levels. It also enhanced activity-and Ca2+-dependent APP phosphorylation and intracellular accumulation of A beta 42. These findings indicate that HSV-1 causes functional changes in cortical neurons that promote APP processing and A beta production, and they are compatible with the co-factorial role for HSV-1 in the pathogenesis of AD suggested by previous findings. (C) 2011 Elsevier Inc. All rights reserved.