A chemical probe to monitor parkinsonism-associated protein DJ-1 in live cells

Oxidative stress is a contingent trigger of Parkinson`s disease (PD). DJ-1, a protein involved in oxidative stress sensing, gained major attention when mutations in its gene were identified in PD patients. Although the study of the corresponding protein function is still in its infancy, a crucial oxidation sensor at a conserved cysteine was linked to the disease. Inspired by inhibition studies with a bacterial homolog of DJ-1 we here screen several amino-epoxycylcohexenones and identify a chemical probe that exhibits specificity for the human protein in various cell lines. The probe selectively labeled the oxidation sensor via nucleophilic attack of the conserved cysteine onto the epoxide ring. This covalent addition occurred only in the reduced state. Whole proteome studies in HeLa, A549 and SHSY5Y cell lines confirmed strong enrichment of solely reduced DJ-1 which was diminished by increasing oxidative stress. The probe thus facilitates the first selective in situ monitoring of DJ-1 in its reduced state and enables studying the function of this important biomarker in dependence of oxidative stress.