A Stage-Specific OTX2 Regulatory Network and Maturation-Associated Gene Programs Are Inherent Barriers to RPE Neural Competency.
A Stage-Specific OTX2 Regulatory Network and Maturation-Associated Gene Programs Are Inherent Barriers to RPE Neural Competency.
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DOI：
10.3389/fcell.2022.875155
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发表时间：
2022
影响因子：
5.5
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视网膜色素上皮（RPE）在脊椎动物中表现出多种可塑性，是视网膜神经元再生的潜在细胞来源。胚胎视网膜具有通过以FGF依赖性方式重编程RPE细胞来再生神经视网膜的短暂能力。鸡胚RPE在胚胎第4天（E4）可再生神经视网膜，但在胚胎第5天（E5）已丧失神经再生能力。为了确定再生能力丧失的机制，我们使用E4和E5鸡RPE以及在视网膜切除术和FGF 2治疗后的两个阶段进行RNA和ATAC测序。我们发现与神经视网膜命运相关的基因在非再生E5 RPE中保持FGF2诱导。与命运限制相一致，RPE细胞稳定地退出细胞周期并抑制在再生期间正常表达的细胞周期进展基因（包括E2F1）的表达。E5 RPE表现出与成熟功能相关的基因途径的进行性激活，独立于视网膜切除术或FGF 2治疗，包括视网膜代谢、色素沉着合成和离子转运。此外，E5 RPE不能有效地抑制响应于FGF2的OTX2表达。预测的OTX2结合基序在E5 RPE中经历稳健的可及性增加，其中许多与已知促进RPE分化和成熟的基因的推定调控元件一致。总之，这些结果揭示了基因调控的广泛改变，最终导致RPE神经能力的丧失，并暗示OTX2是巩固RPE命运的关键决定因素。这些结果产生有价值的洞察力的基础上的RPE谱系限制在早期发育过程中，将是重要的，在了解不同的能力RPE衍生的视网膜再生脊椎动物之间观察。
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), 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.