Shear stress-activated Wnt-angiopoietin-2 signaling recapitulates vascular repair in zebrafish embryos

Arterioscler Thromb Vasc Biol. 2014 Oct;34(10):2268-75. doi: 10.1161/ATVBAHA.114.303345. Epub 2014 Aug 21.


Objective: Fluid shear stress intimately regulates vasculogenesis and endothelial homeostasis. The canonical Wnt/β-catenin signaling pathways play an important role in differentiation and proliferation. In this study, we investigated whether shear stress activated angiopoietin-2 (Ang-2) via the canonical Wnt signaling pathway with an implication in vascular endothelial repair.

Approach and results: Oscillatory shear stress upregulated both TOPflash Wnt reporter activities and the expression of Ang-2 mRNA and protein in human aortic endothelial cells accompanied by an increase in nuclear β-catenin intensity. Oscillatory shear stress-induced Ang-2 and Axin-2 mRNA expression was downregulated in the presence of a Wnt inhibitor, IWR-1, but was upregulated in the presence of a Wnt agonist, LiCl. Ang-2 expression was further downregulated in response to a Wnt signaling inhibitor, DKK-1, but was upregulated by Wnt agonist Wnt3a. Both DKK-1 and Ang-2 siRNA inhibited endothelial cell migration and tube formation, which were rescued by human recombinant Ang-2. Both Ang-2 and Axin-2 mRNA downregulation was recapitulated in the heat-shock-inducible transgenic Tg(hsp70l:dkk1-GFP) zebrafish embryos at 72 hours post fertilization. Ang-2 morpholino injection of Tg (kdrl:GFP) fish impaired subintestinal vessel formation at 72 hours post fertilization, which was rescued by zebrafish Ang-2 mRNA coinjection. Inhibition of Wnt signaling with IWR-1 also downregulated Ang-2 and Axin-2 expression and impaired vascular repair after tail amputation, which was rescued by zebrafish Ang-2 mRNA injection.

Conclusions: Shear stress activated Ang-2 via canonical Wnt signaling in vascular endothelial cells, and Wnt-Ang-2 signaling is recapitulated in zebrafish embryos with a translational implication in vascular development and repair.

Keywords: DKK-1/dickkopfs-1; Wnt signaling; angiopoietin-2; endothelial repairs; human aortic endothelial cells (HAEC); vasculogenesis; zebrafish.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Angiopoietin-2 / genetics
  • Angiopoietin-2 / metabolism*
  • Animals
  • Animals, Genetically Modified
  • Axin Protein / genetics
  • Axin Protein / metabolism
  • Cell Movement
  • Cell Proliferation
  • Cells, Cultured
  • Gene Expression Regulation, Developmental
  • Genes, Reporter
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Human Umbilical Vein Endothelial Cells / metabolism
  • Humans
  • Intercellular Signaling Peptides and Proteins / genetics
  • Intercellular Signaling Peptides and Proteins / metabolism
  • Mechanotransduction, Cellular* / drug effects
  • Neovascularization, Physiologic* / drug effects
  • RNA Interference
  • RNA, Messenger / metabolism
  • Stress, Physiological
  • Time Factors
  • Transfection
  • Wnt Signaling Pathway* / drug effects
  • Wnt3A Protein / metabolism
  • Zebrafish / embryology
  • Zebrafish / genetics
  • Zebrafish / metabolism*
  • Zebrafish Proteins / genetics
  • Zebrafish Proteins / metabolism*


  • ANGPT2 protein, human
  • Angiopoietin-2
  • Axin Protein
  • DKK1 protein, human
  • Intercellular Signaling Peptides and Proteins
  • RNA, Messenger
  • WNT3A protein, human
  • Wnt3A Protein
  • Zebrafish Proteins
  • dkk1b protein, zebrafish
  • Green Fluorescent Proteins