VDAC1-Targeted NHK1 Peptide Recovers Mitochondrial Dysfunction Counteracting Amyloid-β Oligomers Toxicity in Alzheimer's Disease.

Abstract

Mitochondrial dysfunction has been implicated in a broad range of age-related pathologies and has been proposed as a causative factor in Alzheimer's disease (AD). Analysis of post-mortem brains from AD patients showed increased levels of Voltage-dependent anion-selective channel 1 (VDAC1) in the dystrophic neurites surrounding amyloid-β (Aβ) deposits, suggesting a direct association between VDAC1 and mitochondrial toxicity. VDAC1 is the most abundant pore-forming protein of the outer mitochondrial membrane and, as a channel, it plays a pivotal role in regulating cellular bioenergetics, allowing the continuous exchange of ions and metabolites (ATP/ADP, Krebs cycle intermediates) between cytosol and mitochondria. In light of this evidence, we looked into the effects of Aβ oligomers on VDAC1 functions through electrophysiological and respirometric techniques. Our findings indicate that Aβ oligomers significantly modify the conductance, voltage dependency, and kinetic features of VDAC1, as well as its slight selectivity for anions, leading to a marked preference for cations. Given that VDAC1 is mainly involved in the trafficking of charged molecules in and out of mitochondria, a general reduction of cell viability and mitochondrial respiration was detected in neuroblastoma cells and primary cortical neurons exposed to Aβ oligomers. Interestingly, the toxic effect mediated by Aβ oligomers was counteracted by the use of NHK1, a small synthetic, cell-penetrating peptide that binds and modulates VDAC1. On these results, VDAC1 emerges as a crucial molecule in mitochondrial dysfunction in AD and as a promising pharmacological target for the development of new therapeutic avenues for this devastating neurodegenerative disease still without a cure.