Loss of fibrinogen in zebrafish results in an asymptomatic embryonic hemostatic defect and synthetic lethality with thrombocytopenia

Hu, Z., Lavik, K.I., Liu, Y., Vo, A.H., Richter, C.E., Di Paola, J., Shavit, J.A.
Journal of thrombosis and haemostasis : JTH   17(4): 607-617 (Journal)
Registered Authors
Hu, Zhilian, Liu, Yang, Richter, Catherine, Shavit, Jordan, Vo, Andy
fibrinogen, genome editing, hemostasis, thrombocytopenia, zebrafish
MeSH Terms
  • Afibrinogenemia/blood*
  • Afibrinogenemia/metabolism*
  • Animals
  • Animals, Genetically Modified
  • Fibrinogen/genetics
  • Fibrinogen/metabolism*
  • Hemorrhage/blood*
  • Hemorrhage/genetics
  • Hemostasis*/genetics
  • Humans
  • NF-E2 Transcription Factor, p45 Subunit/genetics
  • NF-E2 Transcription Factor, p45 Subunit/metabolism
  • Synthetic Lethal Mutations
  • Thrombocytopenia/blood*
  • Thrombocytopenia/genetics
  • Zebrafish/embryology
  • Zebrafish/genetics
  • Zebrafish/metabolism*
  • Zebrafish Proteins/deficiency
  • Zebrafish Proteins/genetics
  • Zebrafish Proteins/metabolism*
30663848 Full text @ J. Thromb. Haemost.
Mutations in the alpha chain of fibrinogen (FGA), like deficiencies in other fibrinogen subunits, lead to rare inherited autosomal recessive hemostatic disorders. These range from asymptomatic to catastrophic life-threatening bleeds, and the molecular basis of inherited fibrinogen deficiencies is only partially understood. Zinc finger nucleases have been used to produce mutations in zebrafish fga, resulting in overt adult onset hemorrhage and reduced survival.
To determine the age of onset of hemostatic defects in afibrinogenemic zebrafish, and model human fibrinogen deficiencies.
TALEN genome editing (transcription activator-like effector nucleases) was used to generate a zebrafish fga mutant. Hemostatic defects were assessed through survival, gross anatomical and histological observation, and laser-induced endothelial injury. Human FGA variants with unknown pathologies were engineered into the orthologous positions in zebrafish fga.
Loss of Fga decreased survival and resulted in synthetic lethality when combined with thrombocytopenia. Zebrafish fga mutants exhibit a severe hemostatic defect by 3 days of life, but without visible hemorrhage. Induced thrombus formation through venous endothelial injury was completely absent in mutant embryos and larvae. This hemostatic defect was restored by microinjection of wild type fga cDNA plasmid or purified human fibrinogen. This system was used to determine whether unknown human variants were pathological by engineering them into fga.
These studies confirm that loss of fibrinogen in zebrafish results in the absence of hemostasis from the embryonic period through adulthood. When combined with thrombocytopenia, zebrafish exhibit synthetic lethality, demonstrating that thrombocytes are necessary for survival in response to hemorrhage. This article is protected by copyright. All rights reserved.
Genes / Markers
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Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Engineered Foreign Genes