Inhibition of Aβ_1–42 Fibrillation by Chaperonins: Human Hsp60 Is a Stronger Inhibitor than Its Bacterial Homologue GroEL

Abstract

Alzheimer’s disease is a chronic neurodegenerative disease characterized by the accumulation of pathological aggregates of amyloid beta peptide. Many efforts have been focused on understanding peptide aggregation pathways and on identification of molecules able to inhibit aggregation in order to find an effective therapy. As a result, interest in neuroprotective proteins, such as molecular chaperones, has increased as their normal function is to assist in protein folding or to facilitate the disaggregation and/or clearance of abnormal aggregate proteins. Using biophysical techniques, we evaluated the effects of two chaperones, human Hsp60 and bacterial GroEL, on the fibrillogenesis of Aβ1–42. Both chaperonins interfere with Aβ1–42 aggregation, but the effect of Hsp60 is more significant and correlates with its more pronounced flexibility and stronger interaction with ANS, an indicator of hydrophobic regions. Dose-dependent ThT fluorescence kinetics and SAXS experiments reveal that Hsp60 does not change the nature of the molecular processes stochastically leading to the formation of seeds, but strongly delays them by recognition of hydrophobic sites of some peptide species crucial for triggering amyloid formation. Hsp60 reduces the initial chaotic heterogeneity of Aβ1–42 sample at high concentration regimes. The understanding of chaperone action in counteracting pathological aggregation could be a starting point for potential new therapeutic strategies against neurodegenerative diseases.

Valorization of Apple Peels through the Study of the Effects on the Amyloid Aggregation Process of κ-Casein

“…Hence, we tested the APP effect on the Aβ 1-42 peptide involved in Alzheimer' Disease by using the free-dye light scattering technique. It is known that heating from 0 to 37 • C induces, in the Aβ 1-42 peptide, a conversion from coil to beta-strand structures typical of amyloid formation [69]. As shown in Figure 7a, when the Aβ 1-42 peptide is incubated at 37 • C in the presence of APP, the increase found in the light scattered for the Aβ 1-42 peptide alone, and indicative of the aggregation process, was strongly reduced.…”

“…The sample preparation was operated in asepsis using a cold room at 4 • C. Aβ concentration was determined by tyrosine absorption at 276 nm using an extinction coefficient of 1390 cm −1 •M −1 . The aggregation kinetics of 50 µM Aβ 1-42 was monitored by light scattering after incubating the sample at controlled temperature (37 • C) [69,79]. The samples containing 50 µM Aβ and APP were obtained by appropriate aseptic mixing of the protein solutions and placed in closed cuvettes in a cold room at 4 • C, before incubation at higher temperatures.…”

Molecular Chaperones: A Double-Edged Sword in Neurodegenerative Diseases

“…In vitro studies have identified several cytosolic chaperones, such as the sHsps HSPB1, HSPB5, HSPB6, and HSPB8, the J-domain protein DNAJB6, as well as chaperonin that suppress Aβ aggregation, either by inhibiting initial aggregation or recruiting oligomeric species into larger structures (Lee et al, 2006 ; Wilhelmus et al, 2006 ; Shammas et al, 2011 ; Månsson et al, 2014a ; Mangione et al, 2016 ; Vilasi et al, 2019 ). As the sequestration of oligomers reduces the number of particles that can act as seeds this mechanism could help to limit the incorporation of monomers by templated misfolding.…”

“…The lack of available binding sites flanking the amyloid core is probably the reason why the canonical Hsp70 chaperone machinery does not interact with Aβ assemblies (Kakkar et al, 2014 ; Wentink et al, 2019 ). In contrast, the mitochondrial chaperonin HSPD1 can bind to Aβ oligomers, which reduces Aβ-mediated neurotoxicity by preventing Aβ oligomers from interacting with membranes (Marino et al, 2019 ; Vilasi et al, 2019 ). It is tempting to speculate that this function might be conserved by the homologous cytosolic chaperonin CCT, which could help to reduce Aβ toxicity by preventing disruption of intracellular membranes (Julien et al, 2018 ).…”

Development of novel N-(6-methanesulfonyl-benzothiazol-2-yl)-3-(4-substituted-piperazin-1-yl)-propionamides with cholinesterase inhibition, anti-β-amyloid aggregation, neuroprotection and cognition enhancing properties for the therapy of Alzheimer's disease

“…11e) provide the clear evidence that binding interaction of 12 is largely localized at the C-terminal and the bulky side chain of 12 create structural hindrance for salt bridge associated, thus prevent the protein aggregation the pathological state of Alzheimer disease. 47 To further explore the dynamic properties of the investigated structures in our simulations, the essential dynamics (ED) analysis on the Ca atoms was performed. 48 ED actually reects the overall conformational space of protein and protein-12 complex during simulations (Fig.…”