TY - JOUR
T1 - Selenomethionine (Se-Met) induces the cystine/glutamate exchanger SLC7A11 in cultured human retinal pigment epithelial (RPE) cells
T2 - Implications for antioxidant therapy in aging retina
AU - Ananth, Sudha
AU - Miyauchi, Seiji
AU - Thangaraju, Muthusamy
AU - Jadeja, Ravirajsinh N.
AU - Bartoli, Manuela
AU - Ganapathy, Vadivel
AU - Martin, Pamela M.
N1 - Funding Information:
Funding: We would like to acknowledge the funding support for these studies from National Eye Institute grants NIH EY029113 and NIH EY022416 to P.M.M.
Publisher Copyright:
© 2020 by the authors. Licensee MDPI, Basel, Switzerland.
PY - 2021/1
Y1 - 2021/1
N2 - Oxidative damage has been identified as a major causative factor in degenerative diseases of the retina; retinal pigment epithelial (RPE) cells are at high risk. Hence, identifying novel strategies for increasing the antioxidant capacity of RPE cells, the purpose of this study, is important. Specifically, we evaluated the influence of selenium in the form of selenomethionine (Se-Met) in cultured RPE cells on system xc-expression and functional activity and on cellular levels of glutathione, a major cellular antioxidant. ARPE-19 and mouse RPE cells were cultured with and without selenomethionine (Se-Met), the principal form of selenium in the diet. Promoter activity assay, uptake assay, RT-PCR, northern and western blots, and immunofluorescence were used to analyze the expression of xc-, Nrf2, and its target genes. Se-Met activated Nrf2 and induced the expression and function of xc-in RPE. Other target genes of Nrf2 were also induced. System xc-consists of two subunits, and Se-Met induced the subunit responsible for transport activity (SLC7A11). Selenocysteine also induced xc-but with less potency. The effect of Se-met on xc-was associated with an increase in maximal velocity and an increase in substrate affinity. Se-Met increased the cellular levels of glutathione in the control, an oxidatively stressed RPE. The Se-Met effect was selective; under identical conditions, taurine transport was not affected and Na+-coupled glutamate transport was inhibited. This study demonstrates that Se-Met enhances the antioxidant capacity of RPE by inducing the transporter xc-with a consequent increase in glutathione.
AB - Oxidative damage has been identified as a major causative factor in degenerative diseases of the retina; retinal pigment epithelial (RPE) cells are at high risk. Hence, identifying novel strategies for increasing the antioxidant capacity of RPE cells, the purpose of this study, is important. Specifically, we evaluated the influence of selenium in the form of selenomethionine (Se-Met) in cultured RPE cells on system xc-expression and functional activity and on cellular levels of glutathione, a major cellular antioxidant. ARPE-19 and mouse RPE cells were cultured with and without selenomethionine (Se-Met), the principal form of selenium in the diet. Promoter activity assay, uptake assay, RT-PCR, northern and western blots, and immunofluorescence were used to analyze the expression of xc-, Nrf2, and its target genes. Se-Met activated Nrf2 and induced the expression and function of xc-in RPE. Other target genes of Nrf2 were also induced. System xc-consists of two subunits, and Se-Met induced the subunit responsible for transport activity (SLC7A11). Selenocysteine also induced xc-but with less potency. The effect of Se-met on xc-was associated with an increase in maximal velocity and an increase in substrate affinity. Se-Met increased the cellular levels of glutathione in the control, an oxidatively stressed RPE. The Se-Met effect was selective; under identical conditions, taurine transport was not affected and Na+-coupled glutamate transport was inhibited. This study demonstrates that Se-Met enhances the antioxidant capacity of RPE by inducing the transporter xc-with a consequent increase in glutathione.
KW - Age-related macular degeneration (AMD), antioxidants
KW - Glutathione
KW - Oxidative stress
KW - Retina
KW - Retinal pigment epithelium (RPE)
KW - SLC7A11
KW - Selenium
KW - Selenomethionine (Se-Met)
KW - System xc
KW - XCT
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U2 - 10.3390/antiox10010009
DO - 10.3390/antiox10010009
M3 - Article
AN - SCOPUS:85098740306
SN - 2076-3921
VL - 10
SP - 1
EP - 17
JO - Antioxidants
JF - Antioxidants
IS - 1
M1 - 9
ER -