Amyloid Beta Aggregation in the Presence of Temperature-Sensitive Polymers.

Sebastian Funtan,Wolfgang Binder,Zhanna Evgrafova,Daniel Huster,Juliane Adler

doi:10.3390/polym8050178

Sebastian Funtan, Wolfgang Binder + Show 3 more

Open Access

https://doi.org/10.3390/polym8050178

Copy DOI

Abstract

The formation of amyloid fibrils is considered to be one of the main causes for many neurodegenerative diseases, such as Alzheimer’s, Parkinson’s or Huntington’s disease. Current knowledge suggests that amyloid-aggregation represents a nucleation-dependent aggregation process in vitro, where a sigmoidal growth phase follows an induction period. Here, we studied the fibrillation of amyloid β 1-40 (Aβ40) in the presence of thermoresponsive polymers, expected to alter the Aβ40 fibrillation kinetics due to their lower critical solution behavior. To probe the influence of molecular weight and the end groups of the polymer on its lower critical solution temperature (LCST), also considering its concentration dependence in the presence of buffer-salts needed for the aggregation studies of the amyloids, poly(oxazolines) (POx) with LCSTs ranging from 14.2–49.8 °C and poly(methoxy di(ethylene glycol)acrylates) with LCSTs ranging from 34.4–52.7 °C were synthesized. The two different polymers allowed the comparison of the influence of different molecular structures onto the fibrillation process. Mixtures of Aβ40 with these polymers in varying concentrations were studied via time-dependent measurements of the thioflavin T (ThT) fluorescence. The studies revealed that amyloid fibrillation was accelerated in, accompanied by an extension of the lag phase of Aβ40 fibrillation from 18.3 h in the absence to 19.3 h in the presence of the poly(methoxy di(ethylene glycol)acrylate) (3600 g/mol).

Highlights

A wide range of neurodegenerative diseases, such as Alzheimer’s, Parkinson’s or Huntington’s disease, is related to misfolding and aggregation of particular amyloid proteins, leading to the formation of insoluble fibrils [1]
The current study provides a first report on the influence thermoresponsive polymers exert on the fibrillation of an amyloid protein, mixed noncovalently into a fibrillating amyloid system
We synthesized two different polymers, both displaying an lower critical solution temperature (LCST): on the one hand, poly(methoxy di(ethylene glycol)acrylates) 3a–c were prepared by reversible addition-fragmentation chain-transfer polymerization (RAFT) [57,58] starting from methoxy di(ethylene glycol)acrylate 1 [59] and a chain transfer agent (CTA) (2-(n-butyltrithiocarbonylthio) propionic acid 2 [60]) with AIBN as the initiator

Summary

Introduction

A wide range of neurodegenerative diseases, such as Alzheimer’s, Parkinson’s or Huntington’s disease, is related to misfolding and aggregation of particular amyloid proteins, leading to the formation of insoluble fibrils [1]. At the very early stage of the lag phase, when no (larger, detectable) aggregates are present, native soluble proteins combine to form primary nuclei, which are referred to as oligomeric species and protofibrils characterized by a significant β-sheet conformation (Figure 1a) [9,10]. These primary nuclei elongate (Figure 1b), and a secondary nucleation catalyzed by the surface of a growing. Fragmentation (Figure 1d) as a consequence of external forces (e.g., mixing or shaking), which will generate new active chain ends, is possible and will will accelerate accelerate fibril the aggregated fibrils during the the lag lag phase is relatively low fibril growth growth[11]

Methods

Results

Conclusion