Systematic Aβ Analysis in Drosophila Reveals High Toxicity for the 1-42, 3-42 and 11-42 Peptides, and Emphasizes N- and C-Terminal Residues

PLoS One. 2015 Jul 24;10(7):e0133272. doi: 10.1371/journal.pone.0133272. eCollection 2015.

Abstract

Brain amyloid plaques are a hallmark of Alzheimer's disease (AD), and primarily consist of aggregated Aβ peptides. While Aβ 1-40 and Aβ 1-42 are the most abundant, a number of other Aβ peptides have also been identified. Studies have indicated differential toxicity for these various Aβ peptides, but in vivo toxicity has not been systematically tested. To address this issue, we generated improved transgenic Drosophila UAS strains expressing 11 pertinent Aβ peptides. UAS transgenic flies were generated by identical chromosomal insertion, hence removing any transgenic position effects, and crossed to a novel and robust Gal4 driver line. Using this improved Gal4/UAS set-up, survival and activity assays revealed that Aβ 1-42 severely shortens lifespan and reduces activity. N-terminal truncated peptides were quite toxic, with 3-42 similar to 1-42, while 11-42 showed a pronounced but less severe phenotype. N-terminal mutations in 3-42 (E3A) or 11-42 (E11A) resulted in reduced toxicity for 11-42, and reduced aggregation for both variants. Strikingly, C-terminal truncation of Aβ (1-41, -40, -39, -38, -37) were non-toxic. In contrast, C-terminal extension to 1-43 resulted in reduced lifespan and activity, but not to the same extent as 1-42. Mutating residue 42 in 1-42 (A42D, A42R and A42W) greatly reduced Aβ accumulation and toxicity. Histological and biochemical analysis revealed strong correlation between in vivo toxicity and brain Aβ aggregate load, as well as amount of insoluble Aβ. This systematic Drosophila in vivo and in vitro analysis reveals crucial N- and C-terminal specificity for Aβ neurotoxicity and aggregation, and underscores the importance of residues 1-10 and E11, as well as a pivotal role of A42.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Amyloid beta-Peptides / chemistry*
  • Amyloid beta-Peptides / genetics
  • Amyloid beta-Peptides / metabolism*
  • Animals
  • Animals, Genetically Modified
  • Drosophila
  • Drosophila Proteins / genetics
  • Gene Expression
  • Genotype
  • Locomotion / genetics
  • Molecular Sequence Data
  • Protein Aggregation, Pathological
  • Protein Sorting Signals
  • Solubility
  • Transcription Factors / genetics

Substances

  • Amyloid beta-Peptides
  • Drosophila Proteins
  • GAL4 protein, Drosophila
  • Protein Sorting Signals
  • Transcription Factors

Grant support

This work was supported by Swedish VINNOVA, by King Gustaf V's and Queen Victoria’s Freemasons' Foundation, and by AstraZeneca, Sodertalje, to ST, and by the Swedish Research Council to PH. MJ was supported by a VINNOVA grant, "Innovations for future health". The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.