| First Author | Babu E | Year | 2011 |
| Journal | Invest Ophthalmol Vis Sci | Volume | 52 |
| Issue | 8 | Pages | 5749-57 |
| PubMed ID | 21508099 | Mgi Jnum | J:181420 |
| Mgi Id | MGI:5311293 | Doi | 10.1167/iovs.10-6825 |
| Citation | Babu E, et al. (2011) Transport via SLC5A8 (SMCT1) is obligatory for 2-oxothiazolidine-4-carboxylate to enhance glutathione production in retinal pigment epithelial cells. Invest Ophthalmol Vis Sci 52(8):5749-57 |
| abstractText | PURPOSE: To evaluate the role of SLC5A8 in the transport of 2-oxothiazolidine-4-carboxylate (OTC) and to determine whether OTC augments glutathione production in RPE cells, thereby providing protection against oxidative stress. METHODS: SLC5A8-mediated transport of OTC was monitored in Xenopus laevis oocytes by electrophysiological means. Saturation kinetics, Na(+)-activation kinetics, and inhibition by ibuprofen were analyzed by monitoring OTC-induced currents as a measure of transport activity. Oxidative stress was induced in ARPE-19 cells and primary RPE cells isolated from wild type and Slc5a8(-/-) mouse retinas using H(2)O(2), and the effects of OTC on cell death and intracellular glutathione concentration were examined. RESULTS: Heterologous expression of human SLC5A8 in X. laevis oocytes induced Na(+)-dependent inward currents in the presence of OTC under voltage-clamp conditions. The transport of OTC via SLC5A8 was saturable, with a K(t) of 104 +/- 3 muM. The Na(+)-activation kinetics was sigmoidal with a Hill coefficient of 1.9 +/- 0.1, suggesting involvement of two Na(+) in the activation process. Ibuprofen, a blocker of SLC5A8, inhibited SLC5A8-mediated OTC transport; the concentration necessary for half-maximal inhibition was 17 +/- 1 muM. OTC increased glutathione levels and protected ARPE-19 and primary RPE cells isolated from wild type mouse retinas from H(2)O(2)-induced cell death. These effects were abolished in primary RPE isolated from Slc5a8(-/-) mouse retinas. CONCLUSIONS: OTC is a transportable substrate for SLC5A8. OTC augments glutathione production in RPE cells, thereby protecting them from oxidative damage. Transport via SLC5A8 is obligatory for this process. |
