Project description:The retinal pigment epithelium (RPE) exhibits a diverse range of plasticity across vertebrates and is a potential source of cells for the regeneration of retinal neurons. Embryonic amniotes possess a transitory ability to regenerate neural retina through the reprogramming of RPE cells in an FGF-dependent manner. Chicken RPE can regenerate neural retina at embryonic day 4 (E4) of development, but RPE neural competence is lost by embryonic day 5 (E5). To identify mechanisms that underlie loss of regenerative competence, we performed RNA and ATAC sequencing using E4 and E5 chicken RPE, as well as at both stages following retinectomy and FGF2 treatment. We find that genes associated with neural retina fate remain FGF2-inducible in the non-regenerative E5 RPE. Coinciding with fate restriction, RPE cells stably exit the cell cycle and dampen the expression of cell cycle progression genes normally expressed during regeneration, including E2F1. E5 RPE exhibits progressive activation of gene pathways associated with mature function independently of retinectomy or FGF2 treatment, including retinal metabolism, pigmentation synthesis, and ion transport. Moreover, the E5 RPE fails to efficiently repress OTX2 expression in response to FGF2. Predicted OTX2 binding motifs undergo robust accessibility increases in E5 RPE, many of which coincide with putative regulatory elements for genes known to facilitate RPE differentiation and maturation. Together, these results uncover widespread alterations in gene regulation that culminate in the loss of RPE neural competence and implicate OTX2 as a key determinant in solidifying the RPE fate. These results yield valuable insight to the basis of RPE lineage restriction during early development and will be of importance in understanding the varying capacities for RPE-derived retinal regeneration observed among vertebrates.
Project description:The retinal pigment epithelium (RPE) exhibits a diverse range of plasticity across vertebrates and is a potential source of cells for the regeneration of retinal neurons. Embryonic amniotes possess a transitory ability to regenerate neural retina through the reprogramming of RPE cells in an FGF-dependent manner. Chicken RPE can regenerate neural retina at embryonic day 4 (E4) of development, but RPE neural competence is lost by embryonic day 5 (E5). To identify mechanisms that underlie loss of regenerative competence, we performed RNA and ATAC sequencing using E4 and E5 chicken RPE, as well as at both stages following retinectomy and FGF2 treatment. We find that genes associated with neural retina fate remain FGF2-inducible in the non-regenerative E5 RPE. Coinciding with fate restriction, RPE cells stably exit the cell cycle and dampen the expression of cell cycle progression genes normally expressed during regeneration, including E2F1. E5 RPE exhibits progressive activation of gene pathways associated with mature function independently of retinectomy or FGF2 treatment, including retinal metabolism, pigmentation synthesis, and ion transport. Moreover, the E5 RPE fails to efficiently repress OTX2 expression in response to FGF2. Predicted OTX2 binding motifs undergo robust accessibility increases in E5 RPE, many of which coincide with putative regulatory elements for genes known to facilitate RPE differentiation and maturation. Together, these results uncover widespread alterations in gene regulation that culminate in the loss of RPE neural competence and implicate OTX2 as a key determinant in solidifying the RPE fate. These results yield valuable insight to the basis of RPE lineage restriction during early development and will be of importance in understanding the varying capacities for RPE-derived retinal regeneration observed among vertebrates.
Project description:To evaluate the effect of oxidative stress on transcript localization in the retinal pigment epithelium (RPE), we performed poly-A RNA sequencing on nuclear and cytoplasmic fractions from induced pluripotent stem cell-derived retinal pigment epithelium (iPSC-RPE) cells exposed to hydrogen peroxide, as well as untreated controls.
Project description:The retinal pigment epithelium (RPE) provides vital support to photoreceptor cells and its dysfunction is associated with the onset and progression of age-related macular degeneration (AMD). Surgical provision of RPE cells may ameliorate AMD and thus it would be valuable to develop sources of patient-matched RPE cells for this application of regenerative medicine. We describe here the generation of functional RPE-like cells from fibroblasts that represent an important step toward that goal. We identified candidate master transcriptional regulators of RPEs using a novel computational method and then used these regulators to guide exploration of the transcriptional regulatory circuitry of RPE cells and to reprogram human fibroblasts into RPE-like cells. The RPE-like cells share key features with RPEs derived from healthy individuals, including morphology, gene expression and function, and thus represent a step toward the goal of generating patient-matched RPE cells for treatment of macular degeneration. Expression analysis was performed on induced retinal pigment epithelium-like cells.
Project description:The microarray technique was used to investigate gene expression level changes in human retinal pigment epithelium (RPE) microdissected from fetal eyes (13 and 16 weeks of gestation) and adult eyes (40-60 years old). The gene expression analysis of human fetal RPE during development were performed and compared to human native RPE. Of the 45,033 probe sets on the microarray, 30,736 were detected. 3498 differentially expressed genes could be clustered into 8 patterns of expression that were statistically significant. Analyzing expression pattern of genes coding for key functions (pigment synthesis, visual cycle, phagocytosis, adherens and tight junction, transcellular transport) indicates human RPE achieved a high degree of maturity at early pregnancy. Compare to 154 signature genes of RPE, 148 candidate genes were identified in this studies including 53 down-regulated genes and 5 up-regulated genes. qRT2-PCR results showed similar expression trends with the microarray at three time points.These findings indicate human RPE has different expression pattern compared to other animals. A three chip study using total RNA pooled equally from three 13-week fetal eyes, two 16-week fetal eyes and two adult eyes for three time points (13, 16 week gestation and mature adult eye). Experiment was repeated in another group samples. This is a six chip study totally.
Project description:Purpose: The retinal pigment epithelium (RPE) forms the outer blood-retinal barrier. Primary cultures of RPE can model the barrier, but are very sensitive to culture conditions. We examined how the neural retina regulates the RPE transcriptome in a culture model of embryonic development. Attention focused on the tight junctional genes essential for barrier function. Methods: Chick RPE from embryonic day 7 (E7) or embryonic day 14 (E14) was cultured on filters in a serum free medium. Media conditioned by organ culture of neural retinas was applied to the apical surface of the cultured RPE. Fetal bovine serum (2%) was included in some experiments. When the transepithelial electrical resistance (TER) reached a plateau, total RNA was isolated to probe the chick genome on Affymetrix microarrays. The expression tight junctional mRNAs was confirmed by real-time PCR and immunoblotting the protein. Results: The TER was slightly increased by serum, but increased 2-3X by retinal conditioned medium. Serum diminished the effect of retinal conditioned medium. In basal conditions, 86% of the transcriptome expressed during development in vivo was also expressed in culture. Approximately 5% of the transcriptome expressed in culture was absent in vivo. E14 retinal conditioned medium affected 15% of the transcriptome in E7 cultures (24% if serum was included), but only 1.9% in E14 cultures (12% with serum). Examination of 610 genes important for RPE function revealed that mRNAs for 17% were regulated by retinal conditioned medium alone in E7 cultures, compared to 6.2% for E14. For tight junctions, retinal conditioned medium had the most affect on members of the claudin family. These results were confirmed by quantitative real-time PCR. Besides regulating mRNA levels, immunoblotting and immunocytochemistry suggested additional mechanisms whereby retinal secretions regulated protein expression and localization. Conclusions: Gene expression in primary cultures of embryonic RPE resembled the native tissue, but expression, and differentiation, is improved when elements of the normal extracellular environment are replicated in culture. For a small group of proteins, retinal secretions were required to maintain in vivo-like expression in culture. Albeit insufficient, retinal secretions promoted differentiation of immature RPE and helped maintain the properties of more mature RPE. Experiment Overall Design: RPE were isolated from chicken embryos on embryonic day 7 or 14 and cultured, as described <Rahner C, Fukuhara M, Peng S, Kojima S, Rizzolo LJ. The apical and basal environments of the retinal pigment epithelium regulate the maturation of tight junctions during development. J Cell Sci. 2004;117:3307-18>. E7 is when tight junctions of the RPE begin to form; E14 is when tight junctions achieve their mature morphological appearance in vivo. The cells were cultured in medium that contains or lacks E14 retinal conditioned medium. Because serum inhibits the effect of retinal conditioned medium, serum was added to some cultures, resulting in 4 culture conditions for each age. To isolate total RNA, the RNeasy Protect kit (Qiagen) was used according to the manufacturer's protocols. For each culture, 3 independent preparations were used for analysis on Affymetrix microarrays of the chicken genome (Santa Clara, CA). The quality of the total RNA was assessed by the Keck Center, Yale University using formamide gels and a 2100 Bioanalyzer (Agilent Technologies, Santa Clara, CA)
Project description:The microarray technique was used to investigate gene expression level changes in human retinal pigment epithelium (RPE) microdissected from fetal eyes (13 and 16 weeks of gestation) and adult eyes (40-60 years old). The gene expression analysis of human fetal RPE during development were performed and compared to human native RPE. Of the 45,033 probe sets on the microarray, 30,736 were detected. 3498 differentially expressed genes could be clustered into 8 patterns of expression that were statistically significant. Analyzing expression pattern of genes coding for key functions (pigment synthesis, visual cycle, phagocytosis, adherens and tight junction, transcellular transport) indicates human RPE achieved a high degree of maturity at early pregnancy. Compare to 154 signature genes of RPE, 148 candidate genes were identified in this studies including 53 down-regulated genes and 5 up-regulated genes. qRT2-PCR results showed similar expression trends with the microarray at three time points.These findings indicate human RPE has different expression pattern compared to other animals.