Extracellular Hsp90α Detoxifies β-Amyloid Fibrils Through an NRF2 and Autophagy Dependent Pathway

Abstract

We have investigated the role of extracellular Heat shock protein 90 alpha (eHsp90α) in conferring protection of neuronal cells against fibrillary amyloid-beta (f-Aβ1-42) toxicity mediated by microglial cells. The formation of f-Aβ1-42 plaques leads to neurotoxic inflammation, a critical pathological feature of Alzheimer's Disease. We observed increased uptake and clearance of internalized f-Aβ1-42 by microglial cells treated with eHsp90α, an effect associated with activation of NRF2 (NF-E2-related factor 2) - mediated autophagy. eHsp90α thus mitigated the neuronal toxicity of f-Aβ1-42-activated microglia. In addition, eHsp90α facilitated f-Aβ1-42 engulfment by microglial cells in vitro. In summary, eHsp90α triggers NRF2-mediated autophagy in microglia and thus protects against the neurotoxic effects of f-Aβ1-42.