Modeling Disorders of Blood Coagulation in the Zebrafish

Abstract

Hemostasis, the process of blood clot formation and resolution in response to vascular injury, and thrombosis, the dysregulation of hemostasis leading to pathological clot formation, are widely studied. However, the genetic variability in hemostatic and thrombotic disorders is incompletely understood, suggesting that novel mediators have yet to be uncovered. The zebrafish is developing into a powerful in vivo model to study hemostasis, and its features as a model organism are well suited to (a) develop high-throughput screens to identify novel mediators of hemostasis and thrombosis, (b) validate candidate genes identified in human populations, and (c) characterize the structure/function relationship of gene products. In this review, we discuss conservation of the zebrafish hemostatic system, highlight areas for future study, and outline the utility of this model to study blood coagulation and its dysregulation.

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

“…Zebrafish are economical, easy to maintain and manipulate, and undergo rapid, external development as transparent embryos or larvae, making them amenable to hemostatic assays. We and others have demonstrated a high degree of conservation of the coagulation cascade between zebrafish and humans, identifying homologs for nearly all major factors [20][21][22][23][24][25], with strong data implicating mononuclear thrombocytes as functional equivalents to platelets [26,27]. However, thrombocytes have not been proven to be required for survival in response to hemorrhage.…”

Conformational quiescence of ADAMTS‐13 prevents proteolytic promiscuity

“…ADAMTS‐13 is a multi‐domain glycoprotein that proteolyses the A2 domain of von Willebrand factor (VWF) and regulates its hemostatic function 1, 2, 3, 4. Multiple VWF‐binding exosites have been identified across a number of ADAMTS‐13 domains 5, which have informed the development of a so‐called ‘molecular zipper’ model of interaction and proteolysis 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16.…”

Quantitative methods for studying hemostasis in zebrafish larvae

“…In addition to noting the TTO, we can observe the time to first attachment, as well as the number of thrombocytes present in the thrombus at 120 s. Previous studies suggest that these observations relate to the adhesion and aggregation properties of mammalian platelets (Khandekar et al, 2012; Kretz et al, 2015; Lang et al, 2010). …”

“…Unlike mammals, zebrafish possess nucleated thrombocytes, shown to perform many similar functions as mammalian platelets (Carradice & Lieschke, 2008; Kretz, Weyand, & Shavit, 2015; Weyand & Shavit, 2014). Zebrafish thrombocytes exhibit similar aggregation responses to platelet agonists including ADP, collagen, ristocetin, and arachidonic acid.…”

“…Additionally, thrombopoietin, a regulator of platelet production, and its receptor Mpl are conserved in zebrafish. The loss of either results in a decreased number of circulating thrombocytes (Kretz et al, 2015; Lin et al, 2005; Weyand & Shavit, 2014). Several studies in zebrafish have led to novel insights into platelet function, demonstrating their relevance as a model organism for studying platelet development and disorders (Khandekar, Kim, & Jagadeeswaran, 2012; Kretz et al, 2015; Lang, Gihr, Gawaz, & Muller, 2010).…”