Objective: We are investigating the ability of Parkin protein to protect cells from oxidative stress (OS) and the mechanisms that underlie this function. We hypothesize Parkin modulates cellular redox state through direct interaction with oxidants.

Background: About 50 % of early-onset PD is caused by autosomal recessive mutations in the PARK2 gene. Unfortunately, no specific role for Parkin in vivo has been validated; however signs of OS have been reported in humans and animal models of the disease. (Palacino et al, 2004) The present research focuses on Parkin’s role in protecting cells from OS.

Methods: We tested whether Parkin is able to directly mitigate reactive oxygen species (ROS). (1) Antioxidant activity of recombinant Parkin protein was determined using a chemiluminescence assay where the amount of luminescence produced is proportional to the concentration of ROS present within the sample; (2) Parkin’s ability to protect cells from OS was determined using two methods in established cell models overexpressing Parkin. First, production of ROS within the cell was measured using a ROS-specific fluorophore, and second, oxidized and reduced glutathione levels were measured as an indication of the downstream effect of ROS on overall redox state in cells. In both these methods, OS was induced by treatment with H₂O₂.

Results: Our preliminary results suggest that Parkin possesses the capacity to function as an antioxidant. Although it was not able to reduce ROS levels, both the chemiluminescence assay and glutathione measurements post-OS indicate that Parkin can protect the cell from ROS (H₂O₂) induced OS. In the chemiluminescence assay, Parkin was found to be more effective than equimolar amounts of glutathione, which may explain its ability to lower glutathione oxidation.

Conclusions: This is the first study which assesses Parkin’s ability as an antioxidant. The results gathered thus far would suggest that Parkin plays a role in direct ROS migitation and supports some of our previous work suggesting that Parkin protects neurons from oxidizing forces. (LaVoie et al, 2007) Further investigation using different oxidizing forces, measurement of other OS markers and animal PD models are required to further validate our results.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/investigating-the-role-of-parkin-in-mitigating-oxidative-stress/