Genetic reduction of vascular endothelial growth factor receptor 2 rescues aberrant angiogenesis caused by epsin deficiency

Arterioscler Thromb Vasc Biol. 2014 Feb;34(2):331-337. doi: 10.1161/ATVBAHA.113.302586. Epub 2013 Dec 5.


Objective: We previously showed that endothelial epsin deficiency caused elevated vascular endothelial growth factor receptor 2 (VEGFR2) and enhanced VEGF signaling, resulting in aberrant tumor angiogenesis and reduced tumor growth in adult mice. However, direct evidence demonstrating that endothelial epsins regulate angiogenesis specifically through VEGFR2 downregulation is still lacking. In addition, whether the lack of epsins causes abnormal angiogenesis during embryonic development remains unclear.

Approach and results: A novel strain of endothelial epsin-deleted mice that are heterozygous for VEGFR2 (Epn1(fl/fl); Epn2(-/-); Flk(fl/+); iCDH5 Cre mice) was created. Analysis of embryos at different developmental stages showed that deletion of epsins caused defective embryonic angiogenesis and retarded embryo development. In vitro angiogenesis assays using isolated primary endothelial cells (ECs) from Epn1(fl/fl); Epn2(-/-); iCDH5 Cre (EC-iDKO) and Epn1(fl/fl); Epn2(-/-); Flk(fl/+); iCDH5 Cre (EC-iDKO-Flk(fl/+)) mice demonstrated that VEGFR2 reduction in epsin-depleted cells was sufficient to restore normal VEGF signaling, EC proliferation, EC migration, and EC network formation. These findings were complemented by in vivo wound healing, inflammatory angiogenesis, and tumor angiogenesis assays in which reduction of VEGFR2 was sufficient to rescue abnormal angiogenesis in endothelial epsin-deleted mice.

Conclusions: Our results provide the first genetic demonstration that epsins function specifically to downregulate VEGFR2 by mediating activated VEGFR2 internalization and degradation and that genetic reduction of VEGFR2 level protects against excessive angiogenesis caused by epsin loss. Our findings indicate that epsins may be a potential therapeutic target in conditions in which tightly regulated angiogenesis is crucial, such as in diabetic wound healing and tumors.

Keywords: angiogenesis; epsin; receptors, vascular endothelial growth factor.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adaptor Proteins, Vesicular Transport / deficiency*
  • Adaptor Proteins, Vesicular Transport / genetics
  • Animals
  • Carcinoma, Lewis Lung / blood supply*
  • Carcinoma, Lewis Lung / genetics
  • Carcinoma, Lewis Lung / metabolism*
  • Carcinoma, Lewis Lung / pathology
  • Cell Movement
  • Cell Proliferation
  • Cells, Cultured
  • Diabetic Angiopathies / genetics
  • Diabetic Angiopathies / metabolism*
  • Diabetic Angiopathies / pathology
  • Disease Models, Animal
  • Down-Regulation
  • Endothelial Cells / metabolism*
  • Endothelial Cells / pathology
  • Gene Expression Regulation, Developmental
  • Gene Expression Regulation, Neoplastic
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Neovascularization, Pathologic*
  • Neovascularization, Physiologic* / genetics
  • Signal Transduction
  • Time Factors
  • Vascular Endothelial Growth Factor A / metabolism
  • Vascular Endothelial Growth Factor Receptor-2 / deficiency*
  • Vascular Endothelial Growth Factor Receptor-2 / genetics
  • Wound Healing


  • Adaptor Proteins, Vesicular Transport
  • Epn2 protein, mouse
  • Vascular Endothelial Growth Factor A
  • epsin
  • Vascular Endothelial Growth Factor Receptor-2