Munoz-Soriano, V. | bioRxiv Science

bioRxiv2020

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

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.

neuroscience↗

bioRxiv2020

Enhanced activity of glycolytic enzymes in Drosophila and human cell models of Parkinson's disease based on DJ-1 deficiency

Parkinsons disease (PD) is a neurodenerative debilitating disorder characterized by progressive disturbances in motor, autonomic and psychiatric functions. The pathological hallmark of PD is the loss of dopaminergic neurons in the substantia nigra pars compacta, which causes striatal dopamine deficiency. Although most PD cases are sporadic (iPD), approximately 5-10% of all patients suffer from monogenic PD forms caused by highly penetrant rare mutations segregating with the disease in families (fPD). One of the genes linked to monogenic PD is DJ-1. Mutations in DJ-1 cause autosomal recessive early-onset forms of fPD; however, it has been shown that an over-oxidized and inactive form of the DJ-1 protein is found in the brains of iPD individuals. Valuable insights into potential PD pathogenic mechanisms involving DJ-1 have been obtained from studies in cell and animal PD models based on DJ-1 deficiency such as Drosophila. Flies mutant for the DJ-1{beta} gene, the Drosophila ortholog of human DJ-1, exhibited disease-related phenotypes such as motor defects, increased reactive oxygen species production and high levels of protein carbonylation. In the present study, we show that loss of DJ-1{beta} function significantly increased the activities of several regulatory glycolytic enzymes. Similar results were obtained in DJ-1-deficient SH-SY5Y neuroblastoma cells, thus suggesting that loss of DJ-1 function in both PD models produces an enhancement of glycolysis. Our results also show that FDA-approved compounds such as meclizine and dimethyl fumarate, which have different clinical applications, are able to attenuate PD-related phenotypes in both models. Moreover, we found that they could exert their beneficial effect by increasing glycolysis through the activation of key glycolytic enzymes. Taken together, these results are consistent with the idea that increasing glycolysis could be a potential disease-modifying strategy for PD, as recently suggested. Besides, they also support further evaluation and potential repurposing of meclizine and dimethyl fumarate as modulators of energy metabolism for neuroprotection in PD.

neuroscience↗