Shear Stress‐Activated Angiopoeitin‐2 Modulates Endothelial Cell Repairs and Vasculogenesis via Wnt/β‐catenin Signaling Pathway

Abstract

Fluid shear stress is intimately involved in vascular endothelial cell repairs. It is recognized that pulsatile shear stress up‐regulated Angiopoetin‐2 expression (Ang‐2) in human umbilical vein endothelial cells (HUVEC). We hypothesized that Ang‐2 was implicated in HUVEC repairs and vasculogenesis via Wnt/β‐catenin signaling pathway. Knock‐down of Ang‐2 expression with siRNA resulted in an impaired HUVEC migration and tube formation. Wnt3a, a Wnt activator, up‐regulated Ang‐2 mRNA expression (p < 0.05 vs. no addition, n = 3), whereas DKK‐1, a Wnt inhibitor, inhibited Ang‐2 expression (p < 0.05 vs. PBS treated, n = 3), leading to impaired migration and tubule formation. We further demonstrated that subintestinal vessels (SIVs) were absent in heat shock inducible DKK‐1:gfp zebrafish at 72 hpf. Knock‐down of Ang‐2 with morpholino oligomers in the transgenic zebrafish embryo (TG(flk1:GFP)) at 1‐cell stage resulted in impaired vasculogenesis to the entire vasculature at 48 hpf. Treatment with ionomycine, a Calcium (Ca2+) ionophore, also resulted in both impaired HUVEC repairs and suppression of SIV formation in TG(flk1:GFP) lines at 72 hpf as evidenced by down‐regulation of Ang‐2 mRNA expression (p < 0.05 vs. DMSO treatment, n = 3). Taken together, our findings suggest that shear stress‐activated Ang‐2 is implicated in endothelial cell repairs and vasculogenesis via Wnt/β‐catenin signaling pathway.Grant Funding Source : NIH