title: Knocking down 10-Formyltetrahydrofolate dehydrogenase increased oxidative stress and impeded zebrafish embryogenesis by obstructing morphogenetic movement.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Institute of Basic Medical Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan.
authors.forename: Wen-Ni
authors.initials: WN
authors.lastname: Chang
authors.affiliation: Institute of Basic Medical Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan.
authors.forename: Gang-Hui
authors.initials: GH
authors.lastname: Lee
authors.affiliation: Institute of Basic Medical Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan.
authors.forename: Tseng-Ting
authors.initials: TT
authors.lastname: Kao
authors.affiliation: Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan.
authors.forename: Cha-Ying
authors.initials: CY
authors.lastname: Lin
authors.affiliation: Institute of Basic Medical Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan.
authors.forename: Tsun-Hsien
authors.initials: TH
authors.lastname: Hsiao
authors.affiliation: School of Medical Laboratory and Biotechnology, Chung Shan Medical University, Taichung 402, Taiwan.
authors.forename: Jen-Ning
authors.initials: JN
authors.lastname: Tsai
authors.affiliation: Department of Biotechnology, Kaohsiung Medical University, Kao;hsiung 807, Taiwan.
authors.forename: Bing-Hung
authors.initials: BH
authors.lastname: Chen
authors.affiliation: Department of Chemistry, Tamkang University, Taipei 106, Taiwan.
authors.forename: Yau-Hung
authors.initials: YH
authors.lastname: Chen
authors.affiliation: Department of Chemistry, Tamkang University, Taipei 106, Taiwan.
authors.forename: Hsin-Ru
authors.initials: HR
authors.lastname: Wu
authors.affiliation: Institute of Molecular and Cellular Biology, National Taiwan University, Taipei 106, Taiwan.
authors.forename: Huai-Jen
authors.initials: HJ
authors.lastname: Tsai
authors.affiliation: 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. Electronic address: tffu@mail.ncku.edu.tw.
authors.forename: Tzu-Fun
authors.initials: TF
authors.lastname: Fu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D047108:Embryonic Development / Q000235:genetics*; D005492:Folic Acid / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D055785:Gene Knockdown Techniques; D006801:Humans; D009024:Morphogenesis / Q000235:genetics*; D060172:Morpholinos; D018384:Oxidative Stress / Q000235:genetics*; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000235:genetics*; D015027:Zebrafish / Q000235:genetics / Q000254:growth & development; D000099295:Formyltetrahydrofolate Dehydrogenase
chemical_list: D005492:Folic Acid; D060172:Morpholinos; D000587:Oxidoreductases Acting on CH-NH Group Donors; D000099295:Formyltetrahydrofolate Dehydrogenase
keywords: Cell migration; FDH; Folate metabolism; ROS; Zebrafish