Effects of pharmacological agents on the lifespan phenotype of Drosophila DJ-1β mutants

Mutations in the DJ-1 gene cause autosomal recessive, early-onset Parkinsonism. The DJ-1 protein exerts a protective role against oxidative stress damage, working as a cellular oxidative stress sensor, and it seems to regulate gene expression at different levels. In Drosophila, two DJ-1 orthologs have been identified: DJ-1α and DJ-1β. Several studies have shown that loss of DJ-1β function causes Parkinson's disease (PD)-like phenotypes in flies such as age-dependent locomotor defects, reduced lifespan, and enhanced sensitivity to toxins that induce oxidative stress, like the herbicide paraquat. However, no dopaminergic neurodegeneration is observed. These results suggested that both locomotor and lifespan phenotypes could be either related to defects in oxidative stress response, or in dopaminergic physiology as proposed in mice models. In this study, we have employed pharmacological approaches to modify the lifespan phenotype of DJ-1β mutant flies. We have assessed the effects of chronic treatments with antiparkinsonian drugs as well as with antioxidant compounds on such phenotype finding that only antioxidants show statistically significant beneficial effects on DJ-1β mutants' lifespan. These results strongly suggest that oxidative stress plays a causal role in the lifespan phenotype of DJ-1β mutants. Consistent with this, we find that loss of DJ-1β function results in cellular accumulation of reactive oxygen species (ROS) in adult brains, elevated levels of lipid peroxidation and an increased catalase enzymatic activity, thus indicating the existence of high oxidative stress levels in DJ-1β mutants and confirming the essential function of the DJ-1β protein in protecting the organism against oxidative insults. Our study further shows that the lifespan phenotype of DJ-1β mutant flies is amenable to pharmacological intervention, and validates Drosophila as a valuable model for testing and identifying new drugs with therapeutic potential for PD.