December 2002
Volume 43, Issue 13
Free
ARVO Annual Meeting Abstract  |   December 2002
Ecto-Nucleotidases on RPE Cells: a Potential Source of Extracellular Adenosine
Author Affiliations & Notes
  • C Friedman
    Ophthalmology Scheie Eye Institute University of Pennsylvania Philadelphia PA
  • X Zhang
    Ophthalmology Scheie Eye Institute University of Pennsylvania Philadelphia PA
  • AM Laties
    Ophthalmology Scheie Eye Institute University of Pennsylvania Philadelphia PA
  • CH Mitchell
    Physiology University of Pennsylvania Philadelphia PA
  • Footnotes
    Commercial Relationships   C. Friedman, None; X. Zhang, None; A.M. Laties, None; C.H. Mitchell, None. Grant Identification: NIH EY10009-09, Jody Sack Fund, The Foundation Fighting Blindness and Research to Prevent Blindness
Investigative Ophthalmology & Visual Science December 2002, Vol.43, 900. doi:
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    • Get Citation

      C Friedman, X Zhang, AM Laties, CH Mitchell; Ecto-Nucleotidases on RPE Cells: a Potential Source of Extracellular Adenosine . Invest. Ophthalmol. Vis. Sci. 2002;43(13):900.

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

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Abstract

Abstract: : Purpose: Stimulation of adenosine receptors on RPE cells can modify phagocytosis and may influence transport across the cells. The source of adenosine capable of stimulating these receptors is unknown, but in other cells, released ATP is converted to adenosine through a series of extracellular enzymes. As RPE cells can release ATP, this study investigates the presence and activity of ecto-nucleotidases in RPE cells. Methods: A polyclonal antibody to CD-39 (ecto-apyrase; ATP to ADP to AMP) was tested in mouse retina. Ecto-5’nucleotidase (AMP to adenosine) activity was investigated with the lead precipitate reaction on the ARPE-19 line of cultured human RPE cells and albino rat sections. RT-PCR was performed on RNA from ARPE-19 cells with primers for CD39 and CD73 (ecto-5’nucleotidase). Results: CD39 was identified immunohistochemically on both apical and basolateral membranes of mouse RPE. Activity of 5’nucleotidase was detected on non-permeabilized ARPE-19 cells, consistent with extracellular activity from ecto-5’nucleotidase. Activity of 5’nucleotidase was also detected throughout sections of rat RPE cells, although it was not possible to distinguish between an apical and basolateral location. Preliminary RT-PCR data suggests that mRNA transcripts for both CD39 and CD73 are present in ARPE-19 cells. Conclusion: These results suggest that RPE cells possess the ecto-enzymes capable of converting released ATP into adenosine. This could serve as a source of extracellular adenosine capable of stimulating receptors.

Keywords: 306 adenosine • 490 neurotransmitters/neurotransmitter systems • 567 retinal pigment epithelium 
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