SERCA activity is reduced in DJ-1 mutant flies and human cells due to oxidative modification

Abstract

DJ-1 is a causative gene for familial Parkinsons disease (PD) with different functions, standing out its role against oxidative stress (OS). Accordingly, PD model flies harboring a mutation in the DJ-1{beta} gene (the Drosophila ortholog of human DJ-1) show high levels of OS markers like protein carbonylation, a common post-translational modification that may alter protein function. To increase our understanding of PD pathogenesis as well as to discover potential therapeutic targets for pharmacological intervention, we performed a redox proteomic assay in DJ-1{beta} mutant flies. Among the proteins that showed increased carbonylation levels in PD model flies, we found SERCA, an endoplasmic reticulum Ca2+ channel that plays an important role in Ca2+ homeostasis. Several studies have supported the involvement of Ca2+ dyshomeostasis in PD. Interestingly, a functional link between DJ-1 and Ca2+ homeostasis maintenance was previously reported. Thus, we decided to study the relation between SERCA activity and PD physiopathology. Our results showed that SERCA enzymatic activity is significantly reduced in DJ-1{beta} mutant flies, probably as a consequence of OS-induced carbonylation, as well as in a human cell PD model based on DJ-1-deficiency. Indeed, higher carbonylation levels of SERCA were also observed in DJ-1-deficient SH-SY5Y neuron-like cells compared to controls. In addition, we demonstrated that SERCA activity was increased in both PD models after treatment with a specific activator of this protein, CDN1163. Consistently, CDN1163 was also able to restore PD-related phenotypes in PD model flies and to increase viability in the human cell PD model. Taken together, our results indicate that impaired SERCA activity in both familial PD models may play a role in PD physiopathology. In addition, we demonstrate that therapeutic strategies addressing SERCA activation could be beneficial to treat this disease as shown for CDN1163.