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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.

Jonson M, Pokrzywa M, Starkenberg A, Hammarstrom P, Thor S - PLoS ONE (2015)

Bottom Line: To address this issue, we generated improved transgenic Drosophila UAS strains expressing 11 pertinent Aβ peptides.In contrast, C-terminal extension to 1-43 resulted in reduced lifespan and activity, but not to the same extent as 1-42.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Chemistry and Biology, Linkoping University, SE-581 83, Linkoping, Sweden.

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.

No MeSH data available.


Related in: MedlinePlus

Expression of Aβ peptides ending at amino acid 42 shortens lifespan and impairs locomotor activity.(A-C) Lifespan trajectories of Drosophila flies expressing Aβ in the nervous system. (D-F) Locomotor activity analyzed by velocity using iFly. (G) Summary of the median lifespan (50% dead). (H) Summary of the day the velocity reaches the cut-off value of 4 mm/s. Survival plots were calculated using the Kaplan-Meier method. See S1 Table for statistical analyses of differences between the control and all variants.
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pone.0133272.g002: Expression of Aβ peptides ending at amino acid 42 shortens lifespan and impairs locomotor activity.(A-C) Lifespan trajectories of Drosophila flies expressing Aβ in the nervous system. (D-F) Locomotor activity analyzed by velocity using iFly. (G) Summary of the median lifespan (50% dead). (H) Summary of the day the velocity reaches the cut-off value of 4 mm/s. Survival plots were calculated using the Kaplan-Meier method. See S1 Table for statistical analyses of differences between the control and all variants.

Mentions: To test the toxicity of the novel Gal/UAS stocks, we first focused on Aβ 1–42. We found that the n-syb-Gal4/UAS-Aβ-1-42 flies displayed a greatly reduced median lifespan (where 50% of the flies have died), with an average of only 9 days, when compared to the n-syb-Gal4/+ controls (avg. 30 days) (Fig 2A and 2G). Thus, our new transgenic model expressing wt Aβ 1–42 showed a severely reduced lifespan when compared to our previously published studies [13, 22]. Another added benefit was that, in contrast to elav-Gal4, lifespans were not significantly different in males when compared to females (not shown).


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.

Jonson M, Pokrzywa M, Starkenberg A, Hammarstrom P, Thor S - PLoS ONE (2015)

Expression of Aβ peptides ending at amino acid 42 shortens lifespan and impairs locomotor activity.(A-C) Lifespan trajectories of Drosophila flies expressing Aβ in the nervous system. (D-F) Locomotor activity analyzed by velocity using iFly. (G) Summary of the median lifespan (50% dead). (H) Summary of the day the velocity reaches the cut-off value of 4 mm/s. Survival plots were calculated using the Kaplan-Meier method. See S1 Table for statistical analyses of differences between the control and all variants.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4514787&req=5

pone.0133272.g002: Expression of Aβ peptides ending at amino acid 42 shortens lifespan and impairs locomotor activity.(A-C) Lifespan trajectories of Drosophila flies expressing Aβ in the nervous system. (D-F) Locomotor activity analyzed by velocity using iFly. (G) Summary of the median lifespan (50% dead). (H) Summary of the day the velocity reaches the cut-off value of 4 mm/s. Survival plots were calculated using the Kaplan-Meier method. See S1 Table for statistical analyses of differences between the control and all variants.
Mentions: To test the toxicity of the novel Gal/UAS stocks, we first focused on Aβ 1–42. We found that the n-syb-Gal4/UAS-Aβ-1-42 flies displayed a greatly reduced median lifespan (where 50% of the flies have died), with an average of only 9 days, when compared to the n-syb-Gal4/+ controls (avg. 30 days) (Fig 2A and 2G). Thus, our new transgenic model expressing wt Aβ 1–42 showed a severely reduced lifespan when compared to our previously published studies [13, 22]. Another added benefit was that, in contrast to elav-Gal4, lifespans were not significantly different in males when compared to females (not shown).

Bottom Line: To address this issue, we generated improved transgenic Drosophila UAS strains expressing 11 pertinent Aβ peptides.In contrast, C-terminal extension to 1-43 resulted in reduced lifespan and activity, but not to the same extent as 1-42.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Chemistry and Biology, Linkoping University, SE-581 83, Linkoping, Sweden.

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.

No MeSH data available.


Related in: MedlinePlus