Journal
INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE
Volume 49, Issue 1, Pages 310-319Publisher
ASSOC RESEARCH VISION OPHTHALMOLOGY INC
DOI: 10.1167/iovs.07-1041
Keywords
-
Categories
Funding
- NATIONAL EYE INSTITUTE [R01EY004900, R23EY004900] Funding Source: NIH RePORTER
- NEI NIH HHS [EY 04900-25] Funding Source: Medline
Ask authors/readers for more resources
PURPOSE. The authors previously published the novel finding that iron regulates L-glutamate synthesis and accumulation in the cell-conditioned medium (CCM) by increasing cytosolic aconitase activity in cultured lens epithelial cells (LECs), retinal pigment epithelial (RPE) cells, and neurons. The present study was designed to determine whether iron-induced L-glutamate accumulation in the CCM regulates L-cystine uptake and glutathione (GSH) levels through the aconitase pathway in LECs and RPE cells. METHODS. The presence of xCT, the light chain of X-c(-), a glutamate/cystine antiporter, was analyzed by RT-PCR, immunoblotting, and immunocytochemistry. Uptake of L-[S-35] cystine and L-[H-3] glutamate was measured in the presence or absence of transporter inhibitors. L-cystine uptake and intracellular GSH concentration were measured in the presence or absence of iron-saturated transferrin, the iron chelator dipyridyl (DP), or oxalomalic acid (OMA), an aconitase inhibitor. RESULTS. LECs and RPE cells express xCT, as evidenced by RT-PCR analysis and immunoblotting. xCT was localized by immunocytochemistry. The authors found that the iron-induced increase in L-glutamate availability increased L-cystine uptake, with subsequent increases in GSH levels. In addition, L-glutamate production, L-cystine uptake, and GSH concentration were inhibited by OMA and DP, indicating a central role for iron-regulated aconitase activity in GSH synthesis in LECs and RPE cells. CONCLUSIONS. These results demonstrate for the first time that iron regulates L-cystine uptake and the downstream production of GSH in two mammalian cell types. It is possible that the increase in intracellular antioxidant concentration induced by iron serves as a protective mechanism against the well-established capacity of iron to induce oxidative damage.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available