Elsevier

Neuroscience

Volume 132, Issue 1, 2005, Pages 123-135
Neuroscience

Intraneuronal Aβ, non-amyloid aggregates and neurodegeneration in a Drosophila model of Alzheimer’s disease

https://doi.org/10.1016/j.neuroscience.2004.12.025Get rights and content

Abstract

We have developed models of Alzheimer’s disease in Drosophila melanogaster by expressing the Aβ peptides that accumulate in human disease. Expression of wild-type and Arctic mutant (Glu22Gly) Aβ1–42 peptides in Drosophila neural tissue results in intracellular Aβ accumulation followed by non-amyloid aggregates that resemble diffuse plaques. These histological changes are associated with progressive locomotor deficits and vacuolation of the brain and premature death of the flies. The severity of the neurodegeneration is proportional to the propensity of the expressed Aβ peptide to form oligomers. The fly phenotype is rescued by treatment with Congo Red that reduces Aβ aggregation in vitro. Our model demonstrates that intracellular accumulation and non-amyloid aggregates of Aβ are sufficient to cause the neurodegeneration of Alzheimer’s disease. Moreover it provides a platform to dissect the pathways of neurodegeneration in Alzheimer’s disease and to develop novel therapeutic interventions.

Section snippets

Generation of transgenic flies

The Aβ1–42 peptide (underlined) was cloned with a secretion signal peptide from the Drosophila necrotic gene (Green et al., 2000) (MASKVSILLLLTVHLLAAQTFAQDAEFRHDSGYEVHHQKLVFFAEDVGSNKGAIIGLMVGGVVIA) into the Gal4-responsive pUAST expression vector. The QuikChange XL site-directed mutagenesis kit (Stratagene, La Jolla, CA, USA) was used to introduce the Arctic Aβ1–42 mutation (Glu22Gly) and to introduce a premature stop codon, shortening the coding sequence by two amino acids, to produce the Aβ

Drosophila transgenesis

We have tested the hypothesis that intracellular and non-amyloid aggregates of Aβ1–42 are the neurotoxic species in Alzheimer’s disease by expressing Aβ1–42 and other Aβ peptides (fused to a secretion signal peptide) in the neural tissue of D. melanogaster. Independent transgenic lines were derived in which the coding sequences for the Aβ1–42 peptide (Alz42.1, Alz42.2, Alz42.3), the Aβ1–40 peptide (Alz40.1, Alz40.2, Alz40.3), or the Aβ1–42 peptide containing the Arctic mutation (Glu22Gly;

Discussion

The evidence that pro-aggregatory Aβ peptides underlie the neuronal dysfunction and death seen in Alzheimer’s disease is robust (Hardy and Selkoe, 2002). However it is not clear which species is directly neurotoxic and whether the toxic effect is mediated from within the cell or from the extracellular space. We have developed a Drosophila model of Alzheimer’s disease based on the secretion of Aβ peptides to gain insight into these questions. Initially Aβ was expressed in a Drosophila cell line

Acknowledgments

This work was supported by the Wellcome Trust, the Medical Research Council (UK) and Papworth NHS Trust. D.C.C. is a Wellcome Trust Advanced Clinical Fellow, K.J.K. is an MB/PhD student and R.P. is a PhD student, both funded by Merck, Sharpe and Dohme. Work by D.C.G. was supported by a MRC Programme Grant to M. Ashburner, D.C. Gubb and S. Russell. We are grateful to Matthew Savoian, Department of Genetics, University of Cambridge, for his help with microscopy; Neil Wilkie and David Smith, The

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