Iron affects localization of Ght5 in fission yeast.

Iron is an essential cofactor for eukaryotic cells, as well as a toxic metal under certain conditions. On the other hand, glucose is the preferred energy and carbon source by most organisms and is an important signaling molecule in the regulation of biological processes. In Schizosaccharomyces pombe, the Ght5 hexose transporter, known as a high affinity glucose transporter, is required for cell proliferation in low glucose concentrations. Herein, we aimed to investigate the effects of iron stress on the Ght5 hexose transporter under glucose repression and derepression conditions. The effect of iron stress on the expression profile of the ght5 gene was analyzed by RT-qPCR and western blot. The localization of the Ght5-mNeonGreen fusion protein examined with confocal microscopy. Our results revealed that iron stress had an inhibitory effect on ght5 expression, and it altered Ght5 localization on the cell surface, causing it to accumulate in the cytoplasm.

Characterization of hexose transporter genes in the views of the chronological life span and glucose uptake in fission yeast.

Fission yeast, Schizosaccharomyces pombe, possesses eight hexose transporters, Ght1~8. In order to clarify the role of each hexose transporter on glucose uptake, a glucose uptake assay system was established and the actual glucose uptake activity of each hexose transporter-deletion mutant was measured. Under normal growth condition containing 2% glucose, ∆ght5 and ∆ght2 mutants showed large and small decrease in glucose uptake activity, respectively. On the other hand, the other deletion mutants did not show any decrease in glucose uptake activity indicating that, in the presence of Ght5 and Ght2, the other hexose transporters do not play a significant role in glucose uptake. To understand the relevance between glucose uptake and lifespan regulation, we measured the chronological lifespan of each hexose transporter deletion mutant, and found that only ∆ght5 mutant showed a significant lifespan extension. Based on these results we showed that Ght5 is mainly involved in the glucose uptake in Schizosaccharomyces pombe, and suggested that the ∆ght5 mutant has prolonged lifespan due to physiological changes similar to calorie restriction.

Hydrogen peroxide-induced oxidative stress upregulates ght5 gene belonging to hexose transporters in Schizosaccharomyces pombe.

Hydrogen peroxide is an agent that triggers oxidative stress. Glucose, which is a source of carbon and energy has a regulatory role in many metabolic processes such as growth rate, fermentation capacity and stress response. Schizosaccharomyces pombe has eight hexose transporters with a different affinity for glucose and/or related monosaccharides. In S. pombe, Ght5 is a glucose transporter with high-affinity. We aimed to investigate the effects of H2O2-induced oxidative stress on hexose transporters using glucose repression-resistant mutant strains (ird5 and ird11) of S. pombe. We analyzed the percentage of glucose consumption in S. pombe wild-type and mutant cells under stressed and non-stressed conditions. Then we compared the expression levels of the genes encoding hexose transporters under the same conditions. We confirmed that the glucose consumption efficiencies of the mutants were slower than the wild-type as in earlier study under non-stressed condition. The percentage of glucose consumption reduced by approximately two-fold in ird11 and wild-type, but not change in ird5, under a stressed condition. There is no difference between cells shape and size of S. pombe strains under stressed and non-stressed conditions. Under stress-induced condition, the expression levels of ght3, ght4 genes in ird11 and wild-type, and ght4, ght6 genes in ird5 decreased, but that of ght5 gene remarkably increased in only wild-type. We suggested that oxidative stress caused by H2O2 leads to upregulation of the ght5 gene in S. pombe.