Glutathione accumulation with enhanced uptake of cystine induced mild cold stress in HepG2 cells

抄録

Reduced glutathione (GSH) is a unique tripeptide because it plays a key role in redox signaling and xenobiotic detoxification. Additionally, it modulates cell proliferation, apoptosis, immune function, and fibrogenesis. GSH concentrations are finely tuned in cells, making their increase difficult. In rare cases, GSH is induced in the brain during mild therapeutic hypothermia. However, no experimental observations are available to explain this phenomenon. In this study, we measure amino acid and GSH concentrations in HepG2 cells exposed to mild cold stress (MCS) by liquid chromatography coupled with quadrupole-Orbitrap mass spectrometry. In addition, we evaluate cystine uptake in HepG2 cells exposed to MCS using selenocystine (SeCys₂), a selenium-containing analog of cystine. As a result, incubation at 30ºC was the GSH accumulation model for HepG2 cells by MCS. Because cystine concentration at 30°C increased and glutamic acid concentration at 30°C decreased, cystine uptake via the cystine/glutamate transporter xCT was induced by MCS. The results of the cystine uptake test in HepG2 cells exposed to MCS using SeCys₂ are consistent with enhanced cystine uptake via the cystine/glutamate transporter xCT. In summary, we demonstrate that MCS promotes cystine uptake via xCT, inducing GSH accumulation in HepG2 cells.