Pigment Regeneration Mechanisms in the Human Retina

摘要 在过去的2- 30年里，人们已经做了重要的工作来解决光明和黑暗的机制 使用小鼠作为模型系统，在哺乳动物的视杆和视锥光感受器中的适应以及疾病。 然而，老鼠是一种夜行动物，缺乏黄斑，一个专门的中心区域在灵长类视网膜 它提供了对人类日常生存至关重要的高敏锐度色觉。因此，人类的机制 日间视力或破坏黄斑中的光感受器的疾病，例如视网膜相关黄斑变性。 退行性变（AMD）在小鼠中的研究具有挑战性。例如，没有有效的治疗方法， AMD是老年人失明的最常见原因。因此，迫切需要更好地 了解健康和疾病中人类黄斑中光感受器的生物学。尤其如此 视锥细胞和视杆细胞相比的差异已经被更广泛的研究。最近的研究 在小鼠视网膜内建立了光非依赖性和光依赖性色素再生途径 分离自色素上皮（RPE）。这些途径通过Müller细胞再生色素， 光通路（光依赖性和非依赖性视网膜内视觉周期）或感光细胞本身 通过细胞自主再生机制。然而，对于这些机制， 人黄斑或中央凹。该提案的目标是确定独立于RPE的 色素再生途径使视锥细胞能够迅速适应黑暗并在强光下保持敏感性 特别是在人类的黄斑区我们的中心假设是，通过视觉系统运作的典型视觉周期， RPE太慢而不能在强光下维持视力，或在快速变化的视网膜色素水平期间介导暗适应。 人类黄斑的照明。这项工作分为两个具体目标。这些都是为了确定 光非依赖性视网膜内视觉周期（Aim I）和光色素再生途径的贡献 (Aim II）暗适应和维持人黄斑视锥细胞的光敏感性。实验将 使用离体视网膜电图和单细胞抽吸电极记录。这些技术很好地 适用于评估黑暗中视觉周期和细胞自主色素再生途径的作用 光敏感性的适应和维持。我们将利用我们的经验和合作 我们在过去三年中建立了眼库，以制定捐赠标准和协议， 记录来自器官或研究供体人眼的黄斑视锥的光诱发反应1 - 5小时 是死后造成的这些研究的结果将确定不同的视觉周期途径对人类的贡献 由视锥介导的跨越视网膜的地理区域（包括中央凹）的视觉。这些信息将 为阐明黄斑营养不良的发病机制和改善黄斑营养不良的潜在靶点的研究提供基础。 视力或防止老化或患病人眼视力丧失。

ABSTRACT During the past 2-3 decades important work has been done to resolve the mechanisms of light and dark adaptation as well as disease in the mammalian rod and cone photoreceptors using mouse as a model system. However, the mouse is a nocturnal animal that lacks the macula, a specialized central region in primate retina that provides high-acuity color vision critical for human everyday survival. Consequently, mechanisms of human daytime vision or diseases that disrupt photoreceptors in the macula, such as Age-Related Macular Degeneration (AMD), are challenging to study in mice. For example, there is no effective treatment for the dry form of AMD, the most common cause of blindness among the elderly. Thus, there is a critical need to better understand the biology of the photoreceptors in the human macula in health and disease. This is particularly true of cone photoreceptors compared to rods that have been more extensively studied. Recent studies have established both light-independent and light-dependent pigment regeneration pathways within the mouse retina isolated from the pigment epithelium (RPE). These pathways regenerate pigment via Müller cells in cone-specific pathways (light-independent and -dependent intraretinal visual cycles) or in the photoreceptor cells themselves by a cell-autonomous regeneration mechanism. However, nothing is known about these mechanisms in the human macula or fovea. The goal of this proposal is to determine the contribution of the RPE-independent pigment regeneration pathways to the ability of cones to dark adapt quickly and maintain sensitivity in bright light specifically in the human macula. Our central hypothesis is that the canonical visual cycle that operates via the RPE is too slow to maintain vision in bright light or mediate dark adaptation during rapidly changing levels of illumination in the human macula. The work is organized into two specific aims. These are to determine the contribution of the light-independent intraretinal visual cycle (Aim I) and photic pigment regeneration pathways (Aim II) to dark adaptation and maintenance of light sensitivity of human macular cones. The experiments will employ ex vivo electroretinography and single cell suction electrode recordings. These techniques are well suited for assessing the role of visual cycles and cell-autonomous pigment regeneration pathways in dark adaptation and maintenance of light sensitivity, respectively. We will leverage our experience and collaborations with Eye Banks that we have established during the past three years to develop donor criteria and protocols to record light-evoked responses of macular cones from organ or research donor human eyes 1 – 5 hours postmortem. Results of these studies will determine the contribution of different visual cycle pathways to human vision mediated by the cones across geographical regions of the retina, including the fovea. This information will provide a basis for studies to elucidate pathogenesis of macular dystrophies and potential targets to improve vision or prevent vision loss in aging or diseased human eye.