New Chemical Probe May Shed Light on Role of Potential Biomarker in Parkinson’s, Study Suggests

A new chemical probe that binds to a protein called DJ-1 — a sensor of oxidative stress and a potential biomarker of Parkinson’s disease — may help researchers understand how the protein participates in disease progression, a study suggests.

The study, “A chemical probe to monitor the parkinsonism- associated protein DJ-1 in live cells,” was published in the ACS Chemical Biology journal.

Oxidative stress is caused by an imbalance between the body’s production of potentially harmful reactive oxygen species (ROS) and its ability to contain them.

The release of ROS by dopaminergic neurons is one of the underlying causes of Parkinson’s disease. Dopamine is a chemical essential for nerve cell communication and memory formation.

It is no surprise then that patients with a loss of function of the DJ-1 protein — which senses and protects against ROS molecules — often experience an early-onset familial form of Parkinson’s disease.

DJ-1 senses oxidative stress through a specific amino acid, called Cys-106, which becomes oxidized when it comes in contact with reactive oxygen species. This led researchers to hypothesize that DJ-1 could be a biomarker for oxidative stress in Parkinson’s disease.

The problem with this biomarker is that researchers need to distinguish the different forms DJ-1 can take. And while many probes can determine if a cysteine residue is oxidized or reduced, none are specific for this protein, largely hindering its detection.

Researchers in this study investigated a new compound, called aminoepoxycylcohexenones (AECH), which had shown high specificity to a bacterial protein similar to DJ-1.

They examined seven AECH probes and their ability to monitor oxidized DJ-1 levels in live cells. Among them, four strongly bound the protein, and three were moderate inhibitors.

The strong inhibitors rapidly bound the protein, but they also bound it even when mutations were present. However, moderate inhibitors did not label the mutant protein, and one in particular, called FM247, was chosen for additional analysis.

They tested FM247 in two human cell lines from cervical and lung cancer patients, as well as in a cell line relevant for Parkinson’s disease.

In all the different cell lines, the probe showed a clear selectivity for the oxidized DJ-1.

These results support the usefulness of FM247 as a tool for monitoring oxidized DJ-1 levels, which could be an important biomarker for Parkinson’s.

“Furthermore, FM247 and tools derived thereof are promising for imaging of DJ-1 in live cells to obtain direct information of localization and oxidation states,” the researchers concluded.