Mitochondrial Dysfunction in a New Model of Dry AMD

项目摘要 非渗出性或“干性”年龄相关性黄斑变性（AMD）是视力损害的主要原因。 发病率，没有有效的治疗方法。我们的实验室之前已经证实 在香烟烟雾中发现的环境毒物对苯二酚（HQ），污染物， 和塑料，作为干性AMD的潜在原因。我们已经证明，老年小鼠喂养的饮食与 低剂量HQ产生AMD样视网膜下色素上皮（RPE）沉积物。此外，本发明的目的是， 培养的RPE细胞暴露于HQ引发许多非致死性损伤反应 （细胞骨架破坏、细胞“起泡”、胶原蛋白合成增加等）通过激活 特异性胞质信号级联（即ASK 1、p38 MAPK、pHSP 25等）。基于我们 初步研究，我们提出了概念假设，即总部和其他AMD相关 触发物通过诱导线粒体功能障碍促进亚RPE存款形成。 将RPE细胞培养的体外观察结果与体内RPE生物学联系起来已经证明相当 具有挑战性，因为现有的视网膜色素上皮下沉积物的小鼠模型需要老化、遗传 操作、高脂饮食或其他损伤（即蓝光、补体等）。由于这些 模型是时间、成本和资源密集型的，它们不适合深入研究 机制研究来表征亚RPE存款形成的病理生物学。 该R21提案的目的是支持一种新型小鼠模型的探索性研究， 急性RPE下存款形成，通过结膜下暴露于年幼小鼠中的HQ诱导 在两周的时间里，（1）表明这些沉积物是慢性沉积物的前体， 老年小鼠模型;（2）表征存款的相关生化机制 阵具体来说，我们试图证明线粒体功能障碍在 触发调节体内亚RPE存款生物学的细胞质信号传导途径。第二、 我们希望评估RPE下沉积物的ApoE 4脂质失调模型， ApoE 4存款模型和急性眼周HQ模型之间的生物学重叠。最后， 本项目将引入一种新的靶向肽MTP-131，以确定 线粒体功能障碍的治疗是否可以减轻RPE细胞损伤， 可能还有视网膜色素上皮下的沉积物。支持我们概念的积极发现 这一假说将证实线粒体功能障碍作为干性AMD新治疗靶点。

PROJECT SUMMARY Nonexudative, or “dry,” age-related macular degeneration (AMD) is a major cause of visual morbidity, for which there are no effective treatments. Our laboratory has previously implicated the environmental toxicant hydroquinone (HQ), which is found in cigarette smoke, pollutants, and plastics, as a potential cause of dry AMD. We have shown that aged mice fed a diet with low-dose HQ develop AMD-like sub-retinal pigment epithelium (RPE) deposits. Additionally, exposure of cultured RPE cells to HQ triggers numerous nonlethal injury responses (cytoskeletal disruption, cell “blebbing”, increased collagen synthesis, etc.) via activation of specific cytoplasmic signaling cascades (i.e. ASK1, p38 MAPK, pHSP25, others). Based on our preliminary studies, we propose the conceptual hypothesis that HQ and other AMD-relevant triggers promote subRPE deposit formation via induction of mitochondrial dysfunction. Linking in vitro observations of RPE cell culture to in vivo RPE biology has proven quite challenging because existing mouse models of subRPE deposits require aging, genetic manipulations, high-fat diet, or other injury (i.e. blue light, complement, etc.). Since these models are time-, cost-, and resource-intensive, they do not lend themselves to in-depth mechanistic studies to characterize the pathobiology of subRPE deposit formation. The purpose of this R21 proposal is to support exploratory studies of a novel mouse model for acute subRPE deposit formation, induced by subconjunctival exposure to HQ in young mice over a two-week period, (1) to show that these deposits are precursors of deposits in chronic models in aged mice; and (2) to characterize relevant biochemical mechanisms of deposit formation. Specifically, we seek to demonstrate the central role of mitochondrial dysfunction in triggering cytoplasmic signaling pathways that regulate subRPE deposit biology in vivo. Second, we desire to evaluate the ApoE4 lipid dysregulation model of subRPE deposits to assess biologic overlap between the ApoE4 deposit model and the acute periocular HQ model. Finally, this project will introduce a novel mitochondria-targeting peptide, MTP-131, to determine whether treatment of mitochondrial dysfunction can mitigate RPE cellular injury, and prevent and perhaps regress subRPE deposits. Positive findings in support of our conceptual hypothesis would validate mitochondrial dysfunction as a novel therapeutic target for dry AMD.