Dataset Information

Role of amyloid-beta glycine 33 in oligomerization, toxicity, and neuronal plasticity.

ABSTRACT: The aggregation of the amyloid-beta (Abeta) peptide plays a pivotal role in the pathogenesis of Alzheimer's disease, as soluble oligomers are intimately linked to neuronal toxicity and inhibition of hippocampal long-term potentiation (LTP). In the C-terminal region of Abeta there are three consecutive GxxxG dimerization motifs, which we could previously demonstrate to play a critical role in the generation of Abeta. Here, we show that glycine 33 (G33) of the central GxxxG interaction motif within the hydrophobic Abeta sequence is important for the aggregation dynamics of the peptide. Abeta peptides with alanine or isoleucine substitutions of G33 displayed an increased propensity to form higher oligomers, which we could attribute to conformational changes. Importantly, the oligomers of G33 variants were much less toxic than Abeta(42) wild type (WT), in vitro and in vivo. Also, whereas Abeta(42) WT is known to inhibit LTP, Abeta(42) G33 variants had lost the potential to inhibit LTP. Our findings reveal that conformational changes induced by G33 substitutions unlink toxicity and oligomerization of Abeta on the molecular level and suggest that G33 is the key amino acid in the toxic activity of Abeta. Thus, a specific toxic conformation of Abeta exists, which represents a promising target for therapeutic interventions.

SUBMITTER: Harmeier A

PROVIDER: S-EPMC6665404 | biostudies-literature | 2009 Jun

REPOSITORIES: biostudies-literature

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Role of amyloid-beta glycine 33 in oligomerization, toxicity, and neuronal plasticity.

Harmeier Anja A Wozny Christian C Rost Benjamin R BR Munter Lisa-Marie LM Hua Haiqing H Georgiev Oleg O Beyermann Michael M Hildebrand Peter W PW Weise Christoph C Schaffner Walter W Schmitz Dietmar D Multhaup Gerd G

The Journal of neuroscience : the official journal of the Society for Neuroscience 20090601 23

The aggregation of the amyloid-beta (Abeta) peptide plays a pivotal role in the pathogenesis of Alzheimer's disease, as soluble oligomers are intimately linked to neuronal toxicity and inhibition of hippocampal long-term potentiation (LTP). In the C-terminal region of Abeta there are three consecutive GxxxG dimerization motifs, which we could previously demonstrate to play a critical role in the generation of Abeta. Here, we show that glycine 33 (G33) of the central GxxxG interaction motif withi ...[more]

PMID: 19515926

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Project description:A major hallmark of Alzheimer's disease is the misfolding and aggregation of the amyloid- β peptide (Aβ). While early research pointed towards large fibrillar- and plaque-like aggregates as being the most toxic species, recent evidence now implicates small soluble Aβ oligomers as being orders of magnitude more harmful. Techniques capable of characterizing oligomer stoichiometry and assembly are thus critical for a deeper understanding of the earliest stages of neurodegeneration and for rationally testing next-generation oligomer inhibitors. While the fluorescence response of extrinsic fluorescent probes such as Thioflavin-T have become workhorse tools for characterizing large Aβ aggregates in solution, it is widely accepted that these methods suffer from many important drawbacks, including an insensitivity to oligomeric species. Here, we integrate several biophysics techniques to gain new insight into oligomer formation at the single-molecule level. We showcase single-molecule stepwise photobleaching of fluorescent dye molecules as a powerful method to bypass many of the traditional limitations, and provide a step-by-step guide to implementing the technique in vitro. By collecting fluorescence emission from single Aβ(1-42) peptides labelled at the N-terminal position with HiLyte Fluor 555 via wide-field total internal reflection fluorescence (TIRF) imaging, we demonstrate how to characterize the number of peptides per single immobile oligomer and reveal heterogeneity within sample populations. Importantly, fluorescence emerging from Aβ oligomers cannot be easily investigated using diffraction-limited optical microscopy tools. To assay oligomer activity, we also demonstrate the implementation of another biophysical method involving the ratiometric imaging of Fura-2-AM loaded cells which quantifies the rate of oligomer-induced dysregulation of intracellular Ca2+ homeostasis. We anticipate that the integrated single-molecule biophysics approaches highlighted here will develop further and in principle may be extended to the investigation of other protein aggregation systems under controlled experimental conditions.

Dataset Information

Role of amyloid-beta glycine 33 in oligomerization, toxicity, and neuronal plasticity.

Publications

Role of amyloid-beta glycine 33 in oligomerization, toxicity, and neuronal plasticity.

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