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D. C. Baas, S. van Soest, T. G. Gorgels, P. T. V. M. de Jong, J. Stap, A. A. B. Bergen; Gene Expression and Lipofuscin Accumulation in an in vitro Model for Age- Related Macular Degeneration. Invest. Ophthalmol. Vis. Sci. 2007;48(13):3774.
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© ARVO (1962-2015); The Authors (2016-present)
The aim of our study is to identify molecular pathways involved in retinal pigment epithelium (RPE) lipofuscinogenesis in an in vitro model for age- related macular degeneration (AMD).
We cultured ARPE-19 cells on transwell filters, with and without bovine photoreceptor outer segments (POS) in the culture medium, for up to 120 days. Gene expression patterns, using 22K micro arrays, and lipofuscin accumulation of the RPE cells were determined on several time points (56 days, 70 days, 84 days).
Quantative (FACS) and qualitative (image analysis) measurements showed very rapid and progressive accumulation of lipofuscin in RPE cells after adding POS to medium. In contrast, lipofuscin accumulation in controls (no POS in medium) was slow and progressed to much lower levels. Micro array analysis and bioinformatics generated a list of 2723 genes showing significant differences in expression between time point 2 (56 days) and time point 4 (84 days). Trend analysis over all time points of the experiment resulted in 18 genes with a continuous upward trend in gene expression and 34 genes with a continuous downward trend. The upward genes represented an overrepresented group linked to the gene-ontology terms "signal transducer activity" (GO:0004871) and " lipid metabolism" (GO: 0006629). These groups contain genes encoding proteins known to be present in cytoplasm and endoplasmatic reticulum (ER), such as SDCBP (syndecan binding protein (syntenin)).The downward genes represented an overrepresented group linked to the gene-ontology term "collagen" (GO:0005581).This group contains genes encoding proteins known to be present in the extracellular matrix (ECM), such as COL7A1 (Collagen, type VII, alpha 1).
Micro array analysis of an in vitro model of AMD identified 18 genes with an continuous upward trend over time, and 34 genes with a continuous downward trend. These genes and gene expression trends most likely correlate with progressive lipofuscin accumulation in RPE. Our in vitro model can be used to identify pathways involved in lipofuscinogenesis, and may be used for manipulation of lipofuscin accumulation levels.
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