title: Epithelial membrane protein 2 controls VEGF expression in ARPE-19 cells.
abstract: OBJECTIVE
  VEGF production by RPE cells has been shown to be important in regulating aberrant angiogenesis in the retina, which is responsible for multiple types of ocular pathology. EMP2 is highly expressed in the RPE and has been shown to regulate FAK activation, which is implicated in VEGF expression in other cell lines. The purpose of this study was to determine whether EMP2 regulates VEGF expression in the RPE cell line, ARPE-19.
  
  
  METHODS
  ARPE-19 cells were engineered to overexpress EMP2. EMP2 siRNA was used to decrease EMP2 expression. The small molecule inhibitor PP2 was used to inhibit FAK activation. VEGF levels were measured by Western blot and ELISA. Functional differences in secreted VEGF were assayed using HUVEC migration.
  
  
  RESULTS
  VEGF expression levels correlated with levels of EMP2. An increase of VEGF by 150% was observed in EMP2 overexpressing cells as compared with ARPE-19 cells. Concordantly, EMP2 knockdown resulted in a 57% decrease in VEGF expression. HUVEC migration (P = 0.01) and vessel tube formation (P < 0.01) were significantly increased when exposed to cell culture supernatants from EMP2 overexpressing cells.
  
  
  CONCLUSIONS
  This study establishes a novel connection between EMP2 and VEGF and may reflect either a direct effect through the tetraspan web or an indirect change through FAK activation. This connection is functionally significant. In addition to the direct use of anti-VEGF antibodies, modulation of EMP2 with impact on VEGF is potentially a distinct therapeutic target for the treatment of neovascularization associated with retinal diseases that involve pathologic angiogenesis.
authors: Department of Ophthalmology, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, California 90095, USA.
authors: Shawn A
authors: SA
authors: Morales
authors: David G
authors: DG
authors: Telander
authors: Deanna
authors: D
authors: Leon
authors: Krisztina
authors: K
authors: Forward
authors: Jonathan
authors: J
authors: Braun
authors: Madhuri
authors: M
authors: Wadehra
authors: Lynn K
authors: LK
authors: Gordon
mesh_terms: D015153:Blotting, Western; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism / Q000502:physiology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D055213:Retinal Pigment Epithelium / Q000166:cytology / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
chemical_list: C486403:EMP2 protein, human; D008562:Membrane Glycoproteins; D047428:Protein Kinase Inhibitors; D042461:Vascular Endothelial Growth Factor A; D051416:Focal Adhesion Protein-Tyrosine Kinases