June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
PGC-1beta promotes oxidative damage and dysfunction of the retinal pigment epithelium
Author Affiliations & Notes
  • Magali Saint-Geniez
    Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
    Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States
  • Quincy Charles
    Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States
    Boston University School of Medicine, Boston, Massachusetts, United States
  • Mariana Rosales
    Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
    Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States
  • Arogya Khadka
    Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States
  • Gopalan Gnanaguru
    Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
    Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States
  • Jared Iacovelli
    Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
    Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States
  • Footnotes
    Commercial Relationships   Magali Saint-Geniez, None; Quincy Charles, None; Mariana Rosales, None; Arogya Khadka, None; Gopalan Gnanaguru, None; Jared Iacovelli, None
  • Footnotes
    Support  The Grimshaw Foundation (MSG), a Research to Prevent Blindness Unrestricted Grant (MSG), and donations to the Macular Degeneration Research, a program of the BrightFocus Foundation (MSG)
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 3381. doi:
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      Magali Saint-Geniez, Quincy Charles, Mariana Rosales, Arogya Khadka, Gopalan Gnanaguru, Jared Iacovelli; PGC-1beta promotes oxidative damage and dysfunction of the retinal pigment epithelium. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3381.

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

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Abstract

Purpose : Oxidative damage and mitochondrial dysfunctions of the retinal pigment epithelium (RPE) are key early events in age-related macular degeneration but the root mechanisms for RPE pro-angiogenic switch remain unclear. The transcriptional co-activators, PGC-1α and β, are two master regulators of oxidative metabolism in many tissues. We recently demonstrated that PGC-1α controls RPE cells oxidative metabolism and protects cells from cytotoxic oxidative damage. Conversely to PGC-1α, PGC-1β expression in RPE is repressed during RPE maturation in a PGC-1α-dependent manner. Here we further examined the role of PGC-1β in RPE biology and response to oxidative damage.

Methods : Human fetal RPE and ARPE-19 cells were maintained and matured using standard procedures. PGC-1 isoforms gain of function was performed by adenoviral transduction. Mitochondrial respiration was measured with the Seahorse extracellular flux analyzer. Gene expression changes were analyzed by qPCR. Cell death was quantified by LDH assay. Oxidative damage was induced by treatment with H2O2 (0.5 mM for 18 hrs) and oxidized LDL (500 µg/ml for 24 hrs).

Results : Oxygen consumption rate analysis showed that forced expression of PGC-1β stimulates RPE mitochondrial respiration similarly to PGC-1α. Contrary to PGC-1α, PGC-1β significantly repressed the expression of critical antioxidant transcription factors (FOXO3, p<0.05 and NFE2L2, p<0.01) and enzymes (HMOX1, CAT, p<0.01) leading to increased oxidative damage and cell death (p<0.01) in RPE exposed to cytotoxic levels of H2O2 (0.5mM for 18hours). We next evaluated whether AMD-related toxicants could induce PGC-1β expression in cultured RPE and demonstrated that PGC-1β, but not PGC-1α, is selectively induced by cytotoxic doses of oxidized LDL (p=0.0101) while non-oxidized LDL had no effect. In cells exposed to H2O2, PGC-1β was also specifically induced at 6 (p<0.001) and 18 hours (p<0.05) post-treatment. Finally we demonstrated that PGC-1β overexpression in RPE robustly induced Placenta Growth Factor expression (p<0.01) but not VEGFA (p>0.05) and strongly repressed the RPE-secreted anti-angiogenic factors, Thrombospondin-1 (p<0.001) and PEDF (p<0.01).

Conclusions : All together, these findings indicate that PGC-1s exert paradoxical functions in RPE and that pathologic induction of PGC-1β may promote RPE oxidative damage and choroidal neovascularization.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

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