Understanding How Photoswitches Restore Visual Function in Blind Mice

 描述(申请人提供)：视网膜色素变性(RP)和老年性黄斑变性(AMD)是由视杆细胞和视锥细胞退化引起的致盲疾病，导致视觉系统的其余部分完好无损，但无法对光做出反应。一种名为DENAQ的合成化学光开关可以恢复RP盲鼠模型的视觉反应。以前的研究表明，DENAQ对视网膜神经节细胞(RGC)的动作电位放电具有光敏性，但这是如何发生的尚不清楚。该项目的目标是阐明DENAQ光敏化的机制，这对于发现改进的候选药物和优化视力恢复的光刺激策略至关重要。第一个目的是了解为什么DENAQ选择性地感光有死视杆和视锥的小鼠的视网膜，而对有完整的视杆和视锥的健康视网膜没有影响。我们将测试这一假说，即变性导致DENAQ进入视网膜节细胞和/或增强对视网膜节细胞自发放电的离子通道的作用。第二个目的是确定哪些RGC是DENAQ光敏的。在健康的视网膜中，一些RGC在光线开始时激发，一些在偏移时激发，一些在开始和偏移时激发。研究将确定哪些是DENAQ光敏的，以及视杆和视锥的局部退化是否会导致空间受限的RGC光敏化，这与AMD这一局部退行性疾病特别相关。其他研究将揭示DENAQ光敏化是否适用于手术视网膜切除术期间获得的组织样本中的人RGC。第三个目标是利用我们的发现来优化视力恢复。有关DENAQ目标离子通道的信息将有助于开发更具体的光开关。这些通道在视网膜节细胞中的亚细胞定位将使空间上更精确的光控制成为可能。最后，体内成像研究将揭示信号从DENAQ治疗的视网膜传输到盲鼠大脑，验证视觉系统的功能完整性，并为优化视网膜刺激模式提供一个平台，以最好地概括正常的视觉反应。

 DESCRIPTION (provided by applicant): Retinitis pigmentosa (RP) and age-related macular degeneration (AMD) are blinding diseases caused by the degeneration of rods and cones, leaving the rest of the visual system intact but unable to respond to light. A synthetic chemical photoswitch, named DENAQ, can restore visual responses in blind mouse models of RP. Previous studies showed that DENAQ imparts light-sensitivity on action potential firing in retinal ganglion cells (RGC), but how this occurs is unclear. The goal of this project is to elucidate the mechanism of DENAQ photosensitization, crucial for enabling discovery of improved drug candidates and for optimizing photo- stimulation strategies for vision restoration. The first aim i to understand why DENAQ selectively photosensitizes retinas from mice with dead rods and cones while having no effect on healthy retinas with intact rods and cones. We will test the hypothesis that degeneration leads to enhanced entry of DENAQ into RGCs and/or enhanced action on ion channels underlying spontaneous firing in RGCs. The second aim is to identify which RGCs are photosensitized by DENAQ. In the healthy retina, some RGCs fire at light onset, some at offset, and some at onset and offset. Studies will determine which are photosensitized by DENAQ, and whether local degeneration of rods and cones leads to spatially constrained RGC photosensitization, of particular relevance for AMD, a localized degenerative disease. Other studies will reveal whether DENAQ photosensitization applies to human RGCs in tissue samples obtained during surgical retinectomy. The third aim is to exploit our findings to optimize vision restoration. Information about the ion channels targeted by DENAQ will enable development of more specific photoswitches. Subcellular localization of these channels in RGCs will enable more spatially-precise photo-control. Finally imaging studies in vivo will reveal signals transmitted from the DENAQ-treated retina to the brain of blind mice, validating the functional integrity of the visual system and providing a platform for optimizing retinal stimulatin patterns to best recapitulate normal visual responses.