Cellular and molecular mechanisms of retinoic acid-mediated blood-retinal barrier regulation

项目摘要 血-视网膜屏障（BRB）介导分子从血液到视网膜的运动， 保护视网膜神经组织免受潜在有害分子的伤害， 体内平衡BRB的破坏与糖尿病视网膜病变等眼部疾病有关 和老年性黄斑水肿BRB由微血管形成的内屏障和微血管形成的内屏障组成。 内皮细胞和由RPE形成的外屏障。这些细胞之间的紧密连接是 这是屏障功能的关键。然而，调节细胞紧密连接完整性的分子机制， BRB及其破坏对视网膜形态和视功能的影响 明白斑马鱼（Danio Rerio）是研究BRB机制的理想模型 由于其快速的体外视觉发展和广泛的可用性， 一系列基因工具。我们最近已经确定，维甲酸（RA），维生素A的代谢产物， 在防辐射制动器的维护中起着关键作用。斑马鱼幼鱼中RA信号的破坏和 使用泛视黄酸受体抑制剂（BMS 493）的成人导致BRB分解，破坏 视网膜血管和RPE中紧密连接蛋白的表达，以及视力下降。 差异表达基因的初步RNA测序和途径分析表明， mTOR信号通路在用抑制剂处理的鱼的视网膜中显著上调， 与未经处理的鱼相比，RA信号。此外，通过用抗肿瘤药物治疗抑制mTOR信号传导也是有效的。 雷帕霉素足以恢复RA抑制剂处理的幼虫中的BRB完整性。所以我们提出 RA通过与mTOR通路的串扰维持BRB，RA抑制剂诱导的BRB 分解导致视网膜损伤和视觉功能障碍。我们将描述RA的作用， 通过评估BRB中mTOR激活模式， 内部和外部BRB，并确定涉及BMS 493的上游和下游调节器- 引发BRB击穿。我们还将确定视网膜中的哪些细胞有助于RA抑制剂， 诱导的BRB分解，并表征视网膜中的细胞变化作为响应。 了解RA介导的BRB维持的细胞和分子机制 BRB崩溃后视网膜损伤和视力丧失的进展将是至关重要的， 确定预防BRB破坏导致视力丧失的治疗方法。

PROJECT SUMMARY The blood-retinal barrier (BRB) mediates movement of molecules from the blood to the retina, protecting the retinal neural tissue from potentially harmful molecules and maintaining retinal homeostasis. Breakdown of the BRB is associated with ocular diseases such as diabetic retinopathy and age-related macular edema. The BRB consists of both an inner barrier, formed by microvascular endothelial cells, and an outer barrier, formed by the RPE. Tight junctions between these cells are essential to barrier function. However, the molecular mechanisms regulating tight junction integrity in the BRB and the effects of BRB breakdown on retinal morphology and visual function are not fully understood. The zebrafish (Danio Rerio) is an ideal model to investigate the mechanisms of BRB breakdown and maintenance due to its rapid ex vivo visual development and the availability of a wide array of genetic tools. We have recently determined that retinoic acid (RA), a metabolite of Vitamin A, plays a critical role in the maintenance of the BRB. Disruption of RA signaling in zebrafish larvae and adults with a pan-retinoic acid receptor inhibitor (BMS493) results in BRB breakdown, disrupted expression of tight junction proteins in the retinal vasculature and RPE, and decreased visual acuity. Preliminary RNA sequencing and pathway analysis of differentially expressed genes indicates that the mTOR signaling pathway is significantly upregulated in retinas of fish treated with an inhibitor of RA signaling compared to untreated fish. Additionally, inhibition of mTOR signaling by treatment with rapamycin is sufficient to restore BRB integrity in RA-inhibitor-treated larvae. Therefore, we propose that RA maintains the BRB via crosstalk with the mTOR pathway and that RA-inhibitor-induced BRB breakdown leads to retinal damage and visual dysfunction. We will characterize the role of RA and the mTOR signaling pathway in BRB maintenance by assessing the pattern of mTOR activation in the inner and outer BRB and identifying the upstream and downstream regulators involved in BMS493- induced BRB breakdown. We will also determine which cells in the retina contribute to RA-inhibitor- induced BRB breakdown and characterize the cellular changes in the retina in response. Understanding the cellular and molecular mechanisms involved in RA-mediated BRB maintenance and the progression of retinal damage and vision loss following BRB breakdown will be critical to identify therapeutic approaches for preventing vision loss due to BRB disruption.