Delay and restoration of persistent wound-induced retinal pigmented epithelial-to-mesenchymal transition by TGF-beta pathway inhibitors: Implications for age-related macular degeneration
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ABSTRACT: This SuperSeries is composed of the SubSeries listed below.
Project description:Age-related macular degeneration (AMD) is a leading cause of blindness. Most vision loss occurs following the transition from a disease of deposit formation and inflammation to a disease of neovascular fibrosis and/or cell death. Here, we investigate how repeated wound stimulus leads to seminal changes in gene expression and the onset of a perpetual state of stimulus-independent wound response in retinal pigmented epithelial (RPE) cells, a cell-type central to the etiology of AMD. Using a human fetal RPE cell culture model that considers monolayer disruption and subconfluent culture as a proxy for wound stimulus, we have shown that prolonged wound stimulus leads to terminal acquisition of a mesenchymal phenotype post-confluence and altered expression of more than 40% of the transcriptome (see GEO:GSE62224). In contrast, at subconfluence fewer than 5% of expressed transcripts have 2-fold or greater expression differences after repeated passage. Protein-protein and pathway interaction analysis of the genes with passage-dependent expression levels in subconfluent cultures reveals a 158-node interactome comprised of two interconnected modules with functions pertaining to wound response and cell division. Among the wound response genes are the TGFb pathway activators: TGFB1, TGFB2, INHBA, INHBB, GDF6, CTGF, and THBS1. Significantly, inhibition of TGFBR1/ACVR1B mediated signaling using receptor kinase inhibitors both forestalls and reverses the passage-dependent loss of epithelial potential. In this RNA-Seq based transcriptome analysis we show that the TGFb receptor kinase inhibitor, A-83-01, largely reverses the effects of passage and restores the transcriptome profile of Passage 4 RPE highly similar to that seen in differentiated Passage 0 RPE. Examination of mRNA expression in three different primary fetal RPE donor lines in 32 day old passage 0, passage 3, and passage 3 treated with 500 nM A-83-01 cultures
Project description:Age-related macular degeneration (AMD) is a leading cause of blindness. Most vision loss occurs following the transition from a disease of deposit formation and inflammation to a disease of neovascular fibrosis and/or cell death. Here, we investigate how protracted wound stimulus leads to seminal changes in gene expression and the onset of a self-sustained state of wound response in retinal pigmented epithelial (RPE) cells. Using a human fetal RPE cell culture model and a systems level transcriptome analysis, we show that prolonged subconfluent culture resulting from repeated passage, leads to terminal acquisition of a mesenchymal-like phenotype post-confluence accompanied by altered expression of >40% of the transcriptome. In contrast, at subconfluence <5% of transcripts have >2-fold expression changes after repeated passage. Protein-protein interaction analysis reveals a core set of genes comprising two interconnected modules with functions pertaining to wound response and cell division. Among the wound response genes are the TGF-beta pathway activators: TGFB1, TGFG2, INHBA, INHBB, GDF6, CTGF, and THBS1. Small molecule inhibition of TGFBR1/ACVR1B mediated signaling both forestalls and reverses the passage-dependent loss of epithelial potential. Moreover, a disproportionate number of RPE wound response genes have altered expression in neovascular and geographic AMD; including key members of the TGF-beta pathway. In conclusiton, in RPE cells the switch to a terminal mesenchymal-like state following protracted or repeated wound stimulus is driven by activation of a self-perpetuating TGF-beta feedback loop. Targeted inhibition of TGF-beta signaling may be an effective approach towards retarding AMD progression and producing RPE cells in quantity for research and cell based therapies.