April 2010
Volume 51, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2010
Epithelial Membrane Protein 2 (EMP2) Controls VEGF Expression in ARPE-19 Cells
Author Affiliations & Notes
  • S. A. Morales
    Ophthalmology,
    University of California, Los Angeles, Los Angeles, California
  • D. Telander
    Ophthalmology, University of California, Davis, Sacramento, California
  • J. Braun
    Pathology and Laboratory Medicine,
    University of California, Los Angeles, Los Angeles, California
  • L. K. Gordon
    Jules Stein Eye Inst,
    University of California, Los Angeles, Los Angeles, California
    Surgery, Greater Los Angeles VA Healthcare System, Los Angeles, California
  • Footnotes
    Commercial Relationships  S.A. Morales, Patent application pending, P; D. Telander, Patent application pending, P; J. Braun, Patent application pending, P; L.K. Gordon, Patent application pending, P.
  • Footnotes
    Support  VA Merit Grant; A. P. Giannini Fellowship
Investigative Ophthalmology & Visual Science April 2010, Vol.51, 4102. doi:
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    • Get Citation

      S. A. Morales, D. Telander, J. Braun, L. K. Gordon; Epithelial Membrane Protein 2 (EMP2) Controls VEGF Expression in ARPE-19 Cells. Invest. Ophthalmol. Vis. Sci. 2010;51(13):4102.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: : Age-related macular degeneration (AMD) is the primary cause of blindness in people 50 and older in developed countries. VEGF production by retinal pigment epithelial cells has been shown to be a key molecule regulating aberrant angiogenesis in the retina. Epithelial membrane protein 2 (EMP2), a member of the tetraspan protein family, is highly expressed in the RPE and has been shown to regulated FAK activation. FAK signal transduction is implicated in VEGF production. The purpose of this study is to determine whether changes in EMP2 expression modulate VEGF expression levels in RPE.

Methods: : An EMP2 blocking diabody was recombinantly constructed using a phage library. ARPE-19 cells were engineered to overexpress EMP2 (ARPE-19/EMP2). Both ARPE-19 and ARPE-19/EMP2 cells were evaluated for VEGF expression. In some experiments, the cells were pretreated with 20µg/ml of anti-EMP2 or control diabody for 2 hours. The small molecule inhibitor PP2 was used to inhibit FAK activation. VEGF levels were measured by Western Blot and ELISA.

Results: : VEGF expression in ARPE-19/EMP2 cells was about 150% of wild type ARPE-19 cells (P=.003). Exposure to anti-EMP2 diabody resulted in a 75% reduction in EMP2 protein levels. Concordant decreases in basal levels of activated FAK were also observed. Anti-EMP2 diabody treatment reduced VEGF expression by 50% in ARPE-19 (P=.04) and by 40% in the ARPE-19/EMP2 cells(P=.03). VEGF secretion was reduced by 64% in cells treated with PP2.

Conclusions: : This study establishes a novel connection between levels of EMP2 and VEGF and may reflect either a direct effect through the tetraspan web or an indirect change through FAK activation. In addition to the direct use of anti-VEGF antibodies, EMP2 may be an additional therapeutic target for the treatment of neovascular AMD.

Keywords: age-related macular degeneration • vascular endothelial growth factor • retinal pigment epithelium 
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