Regulation of System xc‐ Expression and Localization in a Dopaminergic Cell Line

Abstract

System xc− is a transport system that exchanges extracellular cystine for intracellular glutamate. The transporter plays a role in regulating intracellular cystine and cysteine levels, glutathione synthesis and maintains redox balance within the cell. Thus, the objective of this study was to examine how cellular redox state affects System xc− expression and cellular localization in dopaminergic cells. To manipulate cellular redox state, we exposed cells to either H2O2 or dopamine. We determined that exposure of PC12 cells to exogenous H2O2 (3 mM) or dopamine (10 mM) for 10 min results in an equivalent change in the intracellular H2O2 level in PC12 cells. Following either treatment, System xc− activity increases more than 2‐fold. Our preliminary data suggest that this increase is due to an increase in membrane localization of the transport system. Following oxidative insult, the glutathione levels in the cells are able to recover within one hour and the cells remain protected from cell death for at least 48 hours. Immunocytochemistry studies suggest that System xc− may be localized to a vesicles which may be important in the observed trafficking event. Thus, the regulated trafficking of System xc− may play a significant role in protecting dopaminergic cells form cell death. This research was supported by the Campbell Foundation, the NSF MRI and REU programs and the Biology and Chemistry Departments at Hope College.