Chang Wen-Ni, Lee Gang-Hui, Kao Tseng-Ting, Lin Cha-Ying, Hsiao Tsun-Hsien, Tsai Jen-Ning, Chen Bing-Hung, Chen Yau-Hung, Wu Hsin-Ru, Tsai Huai-Jen, Fu Tzu-Fun
Institute of Basic Medical Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan.
Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan.
Biochim Biophys Acta. 2014 Jul;1840(7):2340-50. doi: 10.1016/j.bbagen.2014.04.009. Epub 2014 Apr 18.
Folate is an essential nutrient for cell survival and embryogenesis. 10-Formyltetrahydrofolate dehydrogenase (FDH) is the most abundant folate enzyme in folate-mediated one-carbon metabolism. 10-Formyltetrahydrofolate dehydrogenase converts 10-formyltetrahydrofolate to tetrahydrofolate and CO2, the only pathway responsible for formate oxidation in methanol intoxication. 10-Formyltetrahydrofolate dehydrogenase has been considered a potential chemotherapeutic target because it was down-regulated in cancer cells. However, the normal physiological significance of 10-Formyltetrahydrofolate dehydrogenase is not completely understood, hampering the development of therapeutic drug/regimen targeting 10-Formyltetrahydrofolate dehydrogenase.
10-Formyltetrahydrofolate dehydrogenase expression in zebrafish embryos was knocked-down using morpholino oligonucleotides. The morphological and biochemical characteristics of fdh morphants were examined using specific dye staining and whole-mount in-situ hybridization. Embryonic folate contents were determined by HPLC.
The expression of 10-formyltetrahydrofolate dehydrogenase was consistent in whole embryos during early embryogenesis and became tissue-specific in later stages. Knocking-down fdh impeded morphogenetic movement and caused incorrect cardiac positioning, defective hematopoiesis, notochordmalformation and ultimate death of morphants. Obstructed F-actin polymerization and delayed epiboly were observed in fdh morphants. These abnormalities were reversed either by adding tetrahydrofolate or antioxidant or by co-injecting the mRNA encoding 10-formyltetrahydrofolate dehydrogenase N-terminal domain, supporting the anti-oxidative activity of 10-formyltetrahydrofolate dehydrogenase and the in vivo function of tetrahydrofolate conservation for 10-formyltetrahydrofolate dehydrogenase N-terminal domain.
10-Formyltetrahydrofolate dehydrogenase functioned in conserving the unstable tetrahydrofolate and contributing to the intracellular anti-oxidative capacity of embryos, which was crucial in promoting proper cell migration during embryogenesis.
These newly reported tetrahydrofolate conserving and anti-oxidative activities of 10-formyltetrahydrofolate dehydrogenase shall be important for unraveling 10-formyltetrahydrofolate dehydrogenase biological significance and the drug development targeting 10-formyltetrahydrofolate dehydrogenase.
叶酸是细胞存活和胚胎发育所必需的营养素。10-甲酰四氢叶酸脱氢酶（FDH）是叶酸介导的一碳代谢中最丰富的叶酸酶。10-甲酰四氢叶酸脱氢酶将10-甲酰四氢叶酸转化为四氢叶酸和二氧化碳，这是甲醇中毒时甲酸盐氧化的唯一途径。10-甲酰四氢叶酸脱氢酶被认为是一种潜在的化疗靶点，因为它在癌细胞中表达下调。然而，10-甲酰四氢叶酸脱氢酶的正常生理意义尚未完全阐明，这阻碍了针对10-甲酰四氢叶酸脱氢酶的治疗药物/方案的开发。
使用吗啉代寡核苷酸敲低斑马鱼胚胎中10-甲酰四氢叶酸脱氢酶的表达。使用特异性染料染色和全胚胎原位杂交检查fdh morphants的形态和生化特征。通过高效液相色谱法测定胚胎叶酸含量。
10-甲酰四氢叶酸脱氢酶在胚胎早期发育过程中在整个胚胎中的表达是一致的，并在后期变得具有组织特异性。敲低fdh会阻碍形态发生运动，导致心脏定位错误、造血缺陷、脊索畸形以及morphants最终死亡。在fdh morphants中观察到F-肌动蛋白聚合受阻和外包延迟。通过添加四氢叶酸或抗氧化剂或共同注射编码10-甲酰四氢叶酸脱氢酶N端结构域的mRNA，这些异常得以逆转，这支持了10-甲酰四氢叶酸脱氢酶的抗氧化活性以及10-甲酰四氢叶酸脱氢酶N端结构域对四氢叶酸的体内保护功能。
10-甲酰四氢叶酸脱氢酶在保护不稳定的四氢叶酸以及增强胚胎细胞内抗氧化能力方面发挥作用，这对于胚胎发育过程中促进细胞正常迁移至关重要。
这些新报道的10-甲酰四氢叶酸脱氢酶的四氢叶酸保护和抗氧化活性对于阐明10-甲酰四氢叶酸脱氢酶的生物学意义以及针对1-甲酰四氢叶酸脱氢酶的药物开发具有重要意义。
