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Aysegul Tura, Mahdy Ranjbar, Christine Örün, Salvatore Grisanti; Outcomes of Insulin-like growth factor-1 treatment on the morphology and junctional integrity of retinal pigment epithelial cells. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2471.
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© ARVO (1962-2015); The Authors (2016-present)
The loss of the polarized, hexagonal morphology of retinal pigment epithelial (RPE) cells is associated with the aging process and considered to be one of the earliest events in the course of age-related macular degeneration (AMD). Though the disruption of cellular junctions is a major incident underlying the depolarisation of many types of epithelial cells, the extracellular factors inducing this process in the RPE cells remain largely unknown. In this study, we analyzed the outcomes of insulin-like growth factor-1 (IGF-1) treatment on the expression of junctional proteins in the RPE cells. We also evaluated the efficacy of the flavonoid Quercetin in the maintenance of junctional integrity and polarized morphology.
Human RPE cells (ScienCell, Provitro, Berlin, Germany, Passages 1-4) were seeded on to poly-L-lysine coated 8-well slides or 6-well plates and allowed to differentiate in normal culture medium (with 2% serum) for 8-10 weeks. Cells were starved overnight in low (0.1%) serum medium and incubated with IGF-1 (100 ng/ml) ± Quercetin (25-100 μM) in low serum medium for 1 day. Protein expression was analyzed by immunocytochemistry and -blotting.
IGF-1 led to a significant decline in the expression of N-Cadherin, beta-catenin, and ZO-1 at the cellular junctions. This was associated with the acquisition of a less polygonal morphology. IGF-1 also resulted in the upregulation of TCF/LEF in the nucleus, suggesting the activation of the beta-Catenin pathway. Addition of Quercetin counteracted these IGF-1-dependent effects and allowed for a more differentiated, hexagonal morphology.
IGF-1 may interfere with the RPE function by disrupting the polarized, differentiated morphology of these cells and thereby be involved in the early pathogenesis of AMD, which deserves further investigation. Administration of the natural flavonoid Quercetin can be considered as a novel approach to alleviate the adverse effects of IGF-1 on the organization of RPE cells.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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