Document Detail

Oxidative stress increases HO-1 expression in ARPE-19 cells, but melanosomes suppress the increase when light is the stressor.
MedLine Citation:
PMID:  23221079     Owner:  NLM     Status:  MEDLINE    
PURPOSE: Phagocytized melanosomes in ARPE-19 cells were previously shown to decrease susceptibility to oxidative stress induced by hydrogen peroxide treatment and increase stress due to light irradiation relative to cells containing control black latex beads. Here we asked whether differential expression of antioxidant enzymes in cells containing pigment granules could explain the outcomes.
METHODS: ARPE-19 cells were loaded by phagocytosis with porcine RPE melanosomes or black latex beads (control particles). Heme oxygenase-1 (HO-1), HO-2, glutathione peroxidase (GPx), and catalase were quantified by Western blot analysis before and after treatment with sublethal hydrogen peroxide or blue light (400-450 nm). The stress was confirmed as sublethal by cell survival analysis using real-time quantification of propidium iodide fluorescence.
RESULTS: Phagocytosis itself produced transient changes in protein levels of some antioxidant enzymes, but steady-state levels (7 days after phagocytosis) did not differ in cells containing melanosomes versus beads. Sublethal stress, induced by either hydrogen peroxide or light, had no effect on catalase or HO-2 in either particle-free or particle-loaded cells. In contrast, HO-1 protein was upregulated by treatment with both hydrogen peroxide and light. Particle content did not affect the HO-1 increase induced by hydrogen peroxide, but the increase induced by blue light irradiation was partially blocked in cells containing black beads and blocked even more in cells containing melanosomes.
CONCLUSIONS: The results do not implicate differential antioxidant enzyme levels in stress protection by melanosomes against hydrogen peroxide, but they suggest a multifaceted role for melanosomes in regulating light stress susceptibility in RPE cells.
Anna Pilat; Anja M Herrnreiter; Christine M B Skumatz; Tadeusz Sarna; Janice M Burke
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2013-01-07
Journal Detail:
Title:  Investigative ophthalmology & visual science     Volume:  54     ISSN:  1552-5783     ISO Abbreviation:  Invest. Ophthalmol. Vis. Sci.     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-01-08     Completed Date:  2013-03-05     Revised Date:  2013-07-11    
Medline Journal Info:
Nlm Unique ID:  7703701     Medline TA:  Invest Ophthalmol Vis Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  47-56     Citation Subset:  IM    
Department of Biophysics, Faculty of Biochemistry, Biophysics, and Biotechnology, Jagiellonian University, Krakow, Poland.
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MeSH Terms
Antioxidants / metabolism
Cell Line
Cell Survival / drug effects,  physiology,  radiation effects
Glutathione Peroxidase / metabolism
Heme Oxygenase-1 / metabolism*
Hydrogen Peroxide / pharmacology
Melanosomes / drug effects,  metabolism*,  radiation effects*
Oxidants / pharmacology
Oxidative Stress / drug effects,  physiology*,  radiation effects*
Phagocytosis / physiology
Retinal Pigment Epithelium* / cytology,  metabolism,  radiation effects
Grant Support
Reg. No./Substance:
0/Antioxidants; 0/Oxidants; 7722-84-1/Hydrogen Peroxide; EC 1.11.1.-/glutathione peroxidase GPX1; EC Peroxidase; EC protein, human; EC Oxygenase-1

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