Abstract 17550: Plasmalemma Vesicle-Associated Protein Promotes Angiogenesis by Stimulation of the Endothelial Production of Pro-Angiogenic Sphingosine 1-Phosphate
Although the molecular mechanisms that govern the formation of a vascular network have been studied intensively, many molecular players still remain unknown or not well understood. To identify potentially new genetic regulators of angiogenesis a cross-species, genome-wide analysis has been performed. Plasmalemma vesicle-associated protein (PLVAP) appeared to be specifically expressed in endothelial cells but its function in angiogenesis remains unknown.
Knockdown of PLVAP in HUVECs using siRNA resulted in an impaired capacity to form tubes (P<0.01, n=6). In the murine retina model PLVAP knockdown significantly diminished vascular network formation (P<0.05, n=10), thus mimicking the in vitro data. To elucidate the molecular function of PLVAP, a proteomics approach was used to identify the direct downstream target. Eukaryotic elongation factor 1A1 (eEF1A1) was identified as a novel binding partner of PLVAP. eEF1A1 is known to stimulate the proangiogenic sphingosine pathway that is located and activated around endothelial caveolae. Binding of PLVAP to eEF1A1 may function as a physical and functional linker between the caveolar-pit and the lid-like PLVAP structure. Evidence for the modulatory function of PLVAP was provided by an in-depth analysis of gene function in which knockdown of PLVAP led to reduced sphingosine kinase 1 (SPHK1) activity (P<0.05, n=8) and decreased levels of its pro-angiogenic product, sphingosine 1-phosphate (S1P) (P<0.01, n=8). The PLVAP knockdown phenotype could be rescued by supplementing S1P to HUVECs (P<0.05, n=8), thus indicating that PLVAP indeed regulates the production of pro-angiogenic S1P.
These findings provide for the first time evidence that the caveolae-associated protein, PLVAP, functions as a regulator of angiogenesis by indirect stimulation of the production of the pro-angiogenic factor S1P via eEF1A1.
- © 2013 by American Heart Association, Inc.