Metabolic changes may precede proteostatic dysfunction in a Drosophila model of amyloid beta peptide toxicity.

Amyloid beta (Aß) peptide aggregation is linked to the initiation of Alzheimer's disease; accordingly, aggregation-prone isoforms of Aß, expressed in the brain, shorten the lifespan of Drosophila melanogaster. However, the lethal effects of Aß are not apparent until after day 15. We used shibire(TS) flies that exhibit a temperature-sensitive paralysis phenotype as a reporter of proteostatic robustness. In this model, we found that increasing age but not Aß expression lowered the flies' permissive temperature, suggesting that Aß did not exert its lethal effects by proteostatic disruption. Instead, we observed that chemical challenges, in particular oxidative stressors, discriminated clearly between young (robust) and old (sensitive) flies. Using nuclear magnetic resonance spectroscopy in combination with multivariate analysis, we compared water-soluble metabolite profiles at various ages in flies expressing Aß in their brains. We observed 2 genotype-linked metabolomic signals, the first reported the presence of any Aß isoform and the second the effects of the lethal Arctic Aß. Lethality was specifically associated with signs of oxidative respiration dysfunction and oxidative stress.

Modeling serpin conformational diseases in Drosophila melanogaster.

Transgenic Drosophila melanogaster have been used to model both the physiological and pathological behavior of serpins. The ability to generate flies expressing serpins and to rapidly assess associated phenotypes contributes to the power of this paradigm. While providing a whole-organism model of serpinopathies the powerful toolkit of genetic interventions allows precise molecular dissection of important biological pathways. In this chapter, we summarize the contribution that flies have made to the serpin field and then describe some of the experimental methods that are employed in these studies. In particular, we will describe the generation of transgenic flies, the assessment of phenotypes, and the principles of how to perform a genetic screen.