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Increased Secondary Nucleation Underlies Accelerated Aggregation of the Four-Residue N-Terminally Truncated Aβ42 Species Aβ5-42

Weiffert, Tanja LU ; Meisl, Georg; Flagmeier, Patrick; De, Suman; Dunning, Christopher J.R. LU ; Frohm, Birgitta LU ; Zetterberg, Henrik LU ; Blennow, Kaj LU ; Portelius, Erik and Klenerman, David, et al. (2019) In ACS Chemical Neuroscience
Abstract

Aggregation of the amyloid-β (Aβ) peptide into plaques is believed to play a crucial role in Alzheimer's disease. Amyloid plaques consist of fibrils of full length Aβ peptides as well as N-terminally truncated species. β-Site amyloid precursor protein-cleaving enzyme (BACE1) cleaves amyloid precursor protein in the first step in Aβ peptide production and is an attractive therapeutic target to limit Aβ generation. Inhibition of BACE1, however, induces a unique pattern of Aβ peptides with increased levels of N-terminally truncated Aβ peptides starting at position 5 (Aβ5-X), indicating that these peptides are generated through a BACE1-independent pathway. Here we elucidate the aggregation mechanism of Aβ5-42 and its influence on... (More)

Aggregation of the amyloid-β (Aβ) peptide into plaques is believed to play a crucial role in Alzheimer's disease. Amyloid plaques consist of fibrils of full length Aβ peptides as well as N-terminally truncated species. β-Site amyloid precursor protein-cleaving enzyme (BACE1) cleaves amyloid precursor protein in the first step in Aβ peptide production and is an attractive therapeutic target to limit Aβ generation. Inhibition of BACE1, however, induces a unique pattern of Aβ peptides with increased levels of N-terminally truncated Aβ peptides starting at position 5 (Aβ5-X), indicating that these peptides are generated through a BACE1-independent pathway. Here we elucidate the aggregation mechanism of Aβ5-42 and its influence on full-length Aβ42. We find that, compared to Aβ42, Aβ5-42 is more aggregation prone and displays enhanced nucleation rates. Aβ5-42 oligomers cause nonspecific membrane disruption to similar extent as Aβ42 but appear at earlier time points in the aggregation reaction. Noteworthy, this implies similar toxicity of Aβ42 and Aβ5-42 and the toxic species are generated faster by Aβ5-42. The increased rate of secondary nucleation on the surface of existing fibrils originates from a higher affinity of Aβ5-42 monomers for fibrils, as compared to Aβ42: an effect that may be related to the reduced net charge of Aβ5-42. Moreover, Aβ5-42 and Aβ42 peptides coaggregate into heteromolecular fibrils and either species can elongate existing Aβ42 or Aβ5-42 fibrils but Aβ42 fibrils are more catalytic than Aβ5-42 fibrils. Our findings highlight the importance of the N-terminus for surface-catalyzed nucleation and thus the production of toxic oligomers.

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published
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keywords
aggregation mechanism, Alzheimer, BACE, coaggregation, Misfolding, toxicity
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ACS Chemical Neuroscience
publisher
The American Chemical Society
external identifiers
  • scopus:85062825981
ISSN
1948-7193
DOI
10.1021/acschemneuro.8b00676
language
English
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yes
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28247142-b9c0-48be-b6eb-65cebfe667a8
date added to LUP
2019-03-22 12:03:39
date last changed
2019-04-23 04:47:17
@article{28247142-b9c0-48be-b6eb-65cebfe667a8,
  abstract     = {<p>Aggregation of the amyloid-β (Aβ) peptide into plaques is believed to play a crucial role in Alzheimer's disease. Amyloid plaques consist of fibrils of full length Aβ peptides as well as N-terminally truncated species. β-Site amyloid precursor protein-cleaving enzyme (BACE1) cleaves amyloid precursor protein in the first step in Aβ peptide production and is an attractive therapeutic target to limit Aβ generation. Inhibition of BACE1, however, induces a unique pattern of Aβ peptides with increased levels of N-terminally truncated Aβ peptides starting at position 5 (Aβ5-X), indicating that these peptides are generated through a BACE1-independent pathway. Here we elucidate the aggregation mechanism of Aβ5-42 and its influence on full-length Aβ42. We find that, compared to Aβ42, Aβ5-42 is more aggregation prone and displays enhanced nucleation rates. Aβ5-42 oligomers cause nonspecific membrane disruption to similar extent as Aβ42 but appear at earlier time points in the aggregation reaction. Noteworthy, this implies similar toxicity of Aβ42 and Aβ5-42 and the toxic species are generated faster by Aβ5-42. The increased rate of secondary nucleation on the surface of existing fibrils originates from a higher affinity of Aβ5-42 monomers for fibrils, as compared to Aβ42: an effect that may be related to the reduced net charge of Aβ5-42. Moreover, Aβ5-42 and Aβ42 peptides coaggregate into heteromolecular fibrils and either species can elongate existing Aβ42 or Aβ5-42 fibrils but Aβ42 fibrils are more catalytic than Aβ5-42 fibrils. Our findings highlight the importance of the N-terminus for surface-catalyzed nucleation and thus the production of toxic oligomers.</p>},
  author       = {Weiffert, Tanja and Meisl, Georg and Flagmeier, Patrick and De, Suman and Dunning, Christopher J.R. and Frohm, Birgitta and Zetterberg, Henrik and Blennow, Kaj and Portelius, Erik and Klenerman, David and Dobson, Christopher M. and Knowles, Tuomas P.J. and Linse, Sara},
  issn         = {1948-7193},
  keyword      = {aggregation mechanism,Alzheimer,BACE,coaggregation,Misfolding,toxicity},
  language     = {eng},
  publisher    = {The American Chemical Society},
  series       = {ACS Chemical Neuroscience},
  title        = {Increased Secondary Nucleation Underlies Accelerated Aggregation of the Four-Residue N-Terminally Truncated Aβ42 Species Aβ5-42},
  url          = {http://dx.doi.org/10.1021/acschemneuro.8b00676},
  year         = {2019},
}