Hsp60 as a novel inhibitor of Amyloid beta misfolding.

The understanding of the biophysical mechanism(s) driving Alzheimer's disease (AD) pathogenesis is critical to devise an effective cure for this age-related terminal disorder affecting millions in the US alone. AD is a pathology related to aging, where several cellular protective mechanisms are impaired, including chaperonins, which are proteins responsible for cellular protection against misfolded peptides. Evidence suggests that misfolding and aggregation into neurotoxic oligomers of the amyloid beta peptide (A?) is a key event in AD pathogenesis. Therefore, understanding the mechanism(s) that may prevent A? aggregation may identify an effective therapeutic target. Some studies have linked A? misfolding with age-related down-regulation of chaperones, particularly in mitochondria where co-localization of the chaperonin Hsp60 and A? it has been suggested. We hypothesize that Hsp60 is protective against A? neurotoxicity via inhibiting its dysfunctional misfolding and subsequent aggregation. To test this hypothesis, we investigated the mechanism involved in Hsp60 inhibition of A? aggregation using both a biophysical and biological approach. Specifically, the A?-Hsp60 interaction was evaluated in a cell-free system by atomic force microscopy (AFM), circular dichroism spectrometry (CD) and high performance liquid chromatography (HPLC). In addition, the interaction between Hsp60 and A? was also evaluated in a cellular model of AD (7PA2 cell line) overexpressing Hsp60 using Western blotting and immunocytochemistry. Our results indicate that Hsp60 is an effective inhibitor of A? toxic aggregation and thus could play a protective role against AD neurodegeneration. Supported in part by NIH grant R01AG042890 to GT.