Kartal Burcu, Palabiyik Bedia
Department of Molecular Biology and Genetics, Institute of Graduate Studies in Sciences, Istanbul University, 34116, Istanbul, Turkey.
Department of Molecular Biology and Genetics, Faculty of Science, Istanbul University, 34134, Istanbul, Turkey.
Cell Mol Biol (Noisy-le-grand). 2019 Jan 31;65(1):73-77.
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 µM) 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-bis-phosphatase (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.
硫胺素二磷酸（ThDP）是碳水化合物、氨基酸和脂质代谢中重要酶的必需辅助因子。还已知硫胺素在某些生物体的应激反应中起重要作用。在本研究中，我们重点关注硫胺素对各种应激源引发的应激反应的影响。为此，首先，在氧化应激、渗透应激和热应激条件下检测了粟酒裂殖酵母细胞培养物的活力。发现仅在氧化应激下，由于细胞外硫胺素（1.5 µM）的存在，细胞活力表现出最高耐受性。然后，在氧化应激条件下，研究了参与抗氧化防御机制的过氧化氢酶和超氧化物歧化酶（SOD）的酶活性，以及与葡萄糖代谢和应激反应途径相关的酶编码基因的表达分析。在此条件下，未观察到硫胺素的存在对SOD和过氧化氢酶活性及其基因表达有任何差异，然而，观察到丙酮酸脱氢酶（pdb1）、转酮醇酶（SPBC2G5.05）、果糖-1,6-二磷酸酶（fbp1）上调，丙酮酸脱羧酶（pdc201）下调。总之，这些发现表明，导致氧化应激抗性的细胞外硫胺素通过将能量产生从发酵转变为呼吸作用，对葡萄糖代谢的调节产生影响。
