title: Notch modulates VEGF action in endothelial cells by inducing Matrix Metalloprotease activity.
abstract: BACKGROUND
  In the vasculature, Notch signaling functions as a downstream effecter of Vascular Endothelial Growth Factor (VEGF) signaling. VEGF regulates sprouting angiogenesis in part by inducing and activating matrix metalloproteases (MMPs). This study sought to determine if VEGF regulation of MMPs was mediated via Notch signaling and to determine how Notch regulation of MMPs influenced endothelial cell morphogenesis.
  
  
  RESULTS
  We assessed the relationship between VEGF and Notch signaling in cultured human umbilical vein endothelial cells. Overexpression of VEGF-induced Notch4 and the Notch ligand, Dll4, activated Notch signaling, and altered endothelial cell morphology in a fashion similar to that induced by Notch activation. Expression of a secreted Notch antagonist (Notch1 decoy) suppressed VEGF-mediated activation of endothelial Notch signaling and endothelial morphogenesis. We demonstrate that Notch mediates VEGF-induced matrix metalloprotease activity via induction of MMP9 and MT1-MMP expression and activation of MMP2. Introduction of a MMP inhibitor blocked Notch-mediated endothelial morphogenesis. In mice, analysis of VEGF-induced dermal angiogenesis demonstrated that the Notch1 decoy reduced perivascular MMP9 expression.
  
  
  CONCLUSIONS
  Taken together, our data demonstrate that Notch signaling can act downstream of VEGF signaling to regulate endothelial cell morphogenesis via induction and activation of specific MMPs. In a murine model of VEGF-induced dermal angiogenesis, Notch inhibition led to reduced MMP9 expression.
authors.affiliation: Pathology and Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, NY, NY 10032, USA. jkk9@columbia.edu.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Funahashi
authors.forename: Carrie J
authors.initials: CJ
authors.lastname: Shawber
authors.forename: Anshula
authors.initials: A
authors.lastname: Sharma
authors.forename: Emi
authors.initials: E
authors.lastname: Kanamaru
authors.forename: Yun K
authors.initials: YK
authors.lastname: Choi
authors.forename: Jan
authors.initials: J
authors.lastname: Kitajewski