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Jérémie Canonica, Tatiana Favez, Laura Kowalczuk, Yvan Arsenijevic, Francine F Behar-Cohen; CSCR and the identification of new molecular mineralocorticoid targets in retinal pigment epithelium cells. Invest. Ophthalmol. Vis. Sci. 2018;59(9):3984.
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© ARVO (1962-2015); The Authors (2016-present)
Inappropriate activation of the mineralocorticoid receptor (MR) is involved in the pathogenesis of central serous chorioretinopathy (CSCR). But whether MR regulates molecular targets in retinal pigment epithelium (RPE) cells is unknown. To answer this question, we stimulated a human iPSC-derived RPE cellular model (iRPE) with various corticosteroids and their antagonists.
Human iPSC cells were differentiated into pure expandable iRPE cells and treated with aldosterone (10-7 M) ± spironolactone (10-5 M) or RU-486 (10-5 M) or cortisol (10-7 M) ± spironolactone (10-5 M) or RU-486 (10-5 M) for 24h. Large-scale transcriptomic analysis was conducted for the untreated control and the aldosterone experimental conditions. Bioinformatic analyses of the RNA-Seq were performed to identify aldosterone-regulated genes and specific signaling pathways. Transepithelial resistance (TER) was measured and specific tight junction proteins expression was evaluated by immunofluorescence.
iRPE cells demonstrated specific RPE markers expression and generated high TER levels. MR and the glucocorticoid receptor (GR) were expressed as mRNA transcript and protein. Aldosterone, cortisol and dexamethasone induced nuclear translocation of both MR and GR. RNA-seq transcriptomic analysis identified 125 up- and 101 down-regulated genes in aldosterone-treated iRPE cells compared to untreated cells. Enrichment analysis predicted cholesterol biosynthetic process (P = 0.041), active transmembrane transporter activity (P = 0.005) and plasma membrane (P = 0.037) to be over-represented in the biological process, the molecular function and the cellular component ontology, respectively. Aldosterone-regulated genes of interest (e.g. SCNN1A, S100A2, PTGER2, PER1, ABCC5 and SERPINF2) were validated by RT-qPCR. Corticosteroids treatments did not have an effect on TER neither on tight junction proteins expression or localization.
Our results demonstrate that iRPE express functional MR and that aldosterone-induced genes regulation is MR-dependent. Therefore, the RPE is a novel non-classical mineralocorticoid tissue to consider in the context of CSCR pathology and the inappropriate MR pathway activation hypothesis. New molecular mineralocorticoid targets identified in this study required further examination to determine their potential implication in epitheliopathy typically observed in CRSC patients.
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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