title: Genetic reduction of vascular endothelial growth factor receptor 2 rescues aberrant angiogenesis caused by epsin deficiency.
abstract: 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.
  
  
  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.
authors: Cardiovascular Biology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.
authors: Kandice L
authors: KL
authors: Tessneer
authors: Cardiovascular Biology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.
authors: Satish
authors: S
authors: Pasula
authors: Cardiovascular Biology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.
authors: Xiaofeng
authors: X
authors: Cai
authors: Cardiovascular Biology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.
authors: Yunzhou
authors: Y
authors: Dong
authors: Cardiovascular Biology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.
authors: John
authors: J
authors: McManus
authors: Cardiovascular Biology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.|Biochemistry and Molecular Biology Department, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
authors: Xiaolei
authors: X
authors: Liu
authors: Cardiovascular Biology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.
authors: Lili
authors: L
authors: Yu
authors: Cardiovascular Biology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.
authors: Scott
authors: S
authors: Hahn
authors: Cardiovascular Biology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.
authors: Baojun
authors: B
authors: Chang
authors: Cardiovascular Biology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.
authors: Yiyuan
authors: Y
authors: Chen
authors: Cardiovascular Biology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.|Cell Biology Department, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
authors: Courtney
authors: C
authors: Griffin
authors: Cardiovascular Biology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.|Biochemistry and Molecular Biology Department, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
authors: Lijun
authors: L
authors: Xia
authors: Max Planck Institute for Molecular Biomedicine, Department of Tissue Morphogenesis, and University of Münster, Faculty of Medicine, Münster, Germany.
authors: Ralf H
authors: RH
authors: Adams
authors: Cardiovascular Biology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.|Biochemistry and Molecular Biology Department, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
authors: Hong
authors: H
authors: Chen
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport / Q000172:deficiency* / Q000235:genetics; D000818:Animals; D018827:Carcinoma, Lewis Lung / Q000098:blood supply* / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002465:Cell Movement; D049109:Cell Proliferation; D002478:Cells, Cultured; D003925:Diabetic Angiopathies / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D004195:Disease Models, Animal; D015536:Down-Regulation; D042783:Endothelial Cells / Q000378:metabolism* / Q000473:pathology; D018507:Gene Expression Regulation, Developmental; D015972:Gene Expression Regulation, Neoplastic; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009389:Neovascularization, Pathologic; D018919:Neovascularization, Physiologic / Q000235:genetics; D015398:Signal Transduction; D013997:Time Factors; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000172:deficiency* / Q000235:genetics; D014945:Wound Healing
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; C577774:Epn2 protein, mouse; D042461:Vascular Endothelial Growth Factor A; C114154:epsin; D040301:Vascular Endothelial Growth Factor Receptor-2
keywords: angiogenesis; epsin; receptors, vascular endothelial growth factor