Unravelling the Role of DJ-1 in Extracellular-Vesicle-Mediated Intercellular Communication

Abstract

Mutations in DJ-1 cause familial Parkinson’s disease. DJ-1 plays a role in protection from oxidative stress, but the relation to PD is unclear. Recently, DJ-1 has been identified at higher concentration in extracellular vesicles (EV) from biological fluids of PD patients, providing a link between EV and a protein associated with PD. EV from neuronal and glial cells have demonstrated roles in synaptic activity, morphological plasticity, neurovascular integrity, contributing to the spread of neurodegeneration. The effects of DJ-1 KO on the EV populations of neuronally-differentiated SH-SY5Y were studied under healthy and rotenone-treated conditions to understand the role of DJ-1 in EV-mediated intercellular communication in PD. EV number was studied via flow cytometry, protein content via mass spectrometry, and function via macrophage migration assays. Results showed that the EV response to increasing rotenone concentration was altered in DJ-1 KO cells. While an EV increased was observed upon rotenone treatment in both genotypes compared to their control, treatment caused a 43 % increase of small EV in DJ-1 KO vs WT. However small EV count did not increase due to DJ-1 KO at 5 nM rotenone. EV protein content was altered at 10 nM rotenone; mass spectrometry identified 117 proteins with different concentrations between the two genotypes, suggesting that DJ-1 is functionally linked to EV production or uptake. While at 10 nM rotenone no increase in cell death was detected, a decrease in mitochondria health in DJ-1 KO vs WT was observed, suggesting EV changes are part of a stress response, not due to dying cells. Furthermore, DJ-1 KO alters the function of EV: at 10 nM rotenone EV from DJ-1 KO stimulated high macrophage migration, with no migration promoted by WT EV. The results provide insights into mechanisms underpinning early stages of DJ-1-linked PD, revealing unknown links between EV and DJ-1.