Proteomic identification of dopamine-conjugated proteins from isolated rat brain mitochondria and SH-SY5Y cells

Abstract

Dopamine oxidation has been previously demonstrated to cause dysfunction in mitochondrial respiration and membrane permeability, possibly related to covalent modification of critical proteins by the reactive dopamine quinone. However, specific mitochondrial protein targets have not been identified. In this study, we utilized proteomic techniques to identify proteins directly conjugated with ¹⁴C-dopamine from isolated rat brain mitochondria exposed to radiolabeled dopamine quinone (150 μM) and differentiated SH-SY5Y cells treated with ¹⁴C-dopamine (150 μM). We observed a subset of rat brain mitochondrial proteins that were covalently modified by ¹⁴C-dopamine, including chaperonin, ubiquinol-cytochrome c reductase core protein 1, glucose regulated protein 75/mitochondrial HSP70/mortalin, mitofilin, and mitochondrial creatine kinase. We also found the Parkinson's disease associated proteins ubiquitin carboxy-terminal hydrolase L1 and DJ-1 to be covalently modified by dopamine in both brain mitochondrial preparations and SH-SY5Y cells. The susceptibility of the identified proteins to covalent modification by dopamine may carry implications for their role in the vulnerability of dopaminergic neurons in Parkinson's disease pathogenesis.