June 2015
Volume 56, Issue 7
Free
ARVO Annual Meeting Abstract  |   June 2015
Effects of advanced glycation end-products (AGEs) on retinal pigment epithelial (RPE) cells lysosomal function: implications for age-related macular degeneration (AMD)
Author Affiliations & Notes
  • Luminita I Paraoan
    Eye & Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
  • Umar Sharif
    Eye & Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
  • Paul Kay
    Eye & Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
  • Ian Grierson
    Eye & Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
  • Yit C Yang
    2Wolverhampton Eye Infirmary, New Cross Hospital, Wolverhampton, United Kingdom
    3School of Life & Health Sciences, Aston University, Birmingham, United Kingdom
  • Simon Harding
    Eye & Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
  • Footnotes
    Commercial Relationships Luminita Paraoan, None; Umar Sharif, None; Paul Kay, None; Ian Grierson, None; Yit Yang, None; Simon Harding, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2015, Vol.56, 4197. doi:https://doi.org/
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      Luminita I Paraoan, Umar Sharif, Paul Kay, Ian Grierson, Yit C Yang, Simon Harding; Effects of advanced glycation end-products (AGEs) on retinal pigment epithelial (RPE) cells lysosomal function: implications for age-related macular degeneration (AMD). Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):4197. doi: https://doi.org/.

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

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Abstract

Purpose: RPE lysosomal dysfunction is a major contributor to AMD pathogenesis. Controlled activity of a major class of RPE proteinases, the cathepsins, is crucial in maintaining correct lysosomal function. Advanced glycation end-products (AGEs) accumulate in the Bruch’s membrane (BM) with age, impacting critical RPE functions and in turn, contributing to the development of AMD. The aim of this study was to assess the effect of AGEs on lysosomal function by analysing the expression, processing and activity of the cysteine proteinases cathepsins B, L and S, and the aspartic proteinase cathepsin D.

Methods: ARPE-19 cells were cultured on AGE-containing BM mimics (matrigel) for 14 days and compared to untreated substrate. Expression levels and intracellular processing of cathepsins B, D, L and S, were assessed by qPCR and immunoblotting of cell lysates. Lysosomal activity was investigated using multiple activity assays specific to each of the analysed cathepsins. Statistical analysis was performed using the Student’s independent T-test.

Results: AGE exposure produced a 36% decrease in cathepsin L activity when compared to non-treated controls (p=0.02, n= 3) although no significant changes were observed in protein expression/processing under these conditions. Both the pro and active forms of cathepsin S decreased by 40% (p=0.04) and 74% (p=0.004), respectively (n=3). In contrast, the active form of the cathepsin D increased by 125% (p=0.005, n= 4). However, no changes were observed in the activity levels of both cathepsins S and D. In addition, cathepsin B expression, processing and activity also remained unaltered following AGE exposure.

Conclusions: AGEs accumulation in the extracellular matrix, a phenomenon associated with the natural aging process of the BM, attenuates the expression, intracellular processing and activity of specific lysosomal effectors. Altered enzymatic function may impair important lysosomal processes such as endocytosis, autophagy and phagocytosis of photoreceptor outer segments, each of which may influence the age-related dysfunction of the RPE and subsequently, AMD pathogenesis.

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