Thiamine leads to oxidative stress resistance via regulation of the glucose metabolism

Thiamine diphosphate (ThDP) is an essential cofactor for important enzymes in carbohydrate, amino acid and lipid metabolisms. It is also known that thiamine plays an important role in stress response of some organisms. In this study, we focused on the effect of thiamine on stress responses triggered by various stress agents. For this purpose, firstly, viability of Schizosaccharomyces pombe cell cultures was examined under oxidative, osmotic and heat stresses. The highest tolerance observed in cell viability due to the presence of extracellular thiamine (1.5 mu M) was found only against oxidative stress. Then. enzyme activity of catalase and superoxide dismutase (SOD) involved in antioxidant defense mechanism and the expression analysis of genes encoding enzymes related to glucose metabolism and stress response pathways were investigated under oxidative stress. In this condition, it was not observed any difference in SOD and catalase activities, and their gene expressions due to the presence of thiamine, whereas the upregulation of pyruvate dehydrogenase (pdb1), transketolase (SPBC2G5.05). fructose-1,6-bisphosphatase (fbp1) and the downregulation of pyruvate decarboxylase (pdc201) were observed. In conclusion, these findings suggest that extracellular thiamine leading to oxidative stress resistance have an impact on the regulation of glucose metabolism by shifting the energy generation from fermentation to respiration.