Cone Opsin-Ligand Interactions and Photoreceptor Health

项目总结/摘要 该项目的主要目标是了解导致感光细胞的潜在事件 当类维生素A代谢出现问题时， 从退化。在Leber先天性黑蒙2型（LCA 2）中， 视色素的发色团（11-顺式视网膜）受到抑制。在LCA 2小鼠模型中，视锥细胞死亡 迅速对短波长敏感（SWS 1）的视锥细胞损害最严重。这种模式大致 与LCA 2的发病机制相似。其他实验室的研究表明， 治疗可以恢复视力，但在治疗前受到不可逆的视锥细胞损失的限制。早期 对小鼠模型给予外源性11-顺式视黄醛可改善视锥细胞存活，但 该实验室最近的工作表明，当小鼠受到 房间灯光这些结果表明：（1）视锥细胞视蛋白/11-顺式视网膜的相互作用是重要的， 预防视锥细胞死亡，和（2）11-顺式视黄醇将不是治疗LCA 2的解决方案，因为正常 光照条件抵消了它的好处。因为视锥细胞视蛋白是组成性活性的，但随着视锥细胞视蛋白活性的降低而失活。 11-cis retinal，该项目的假设是活性视锥视蛋白水平的增加导致 LCA 2的视锥细胞变性。因此，使视锥细胞视蛋白失活的光不敏感的小分子将被抑制。 当内源性11-顺式视黄醇有限时，对视锥细胞有保护作用。初步数据显示贝塔 紫罗兰酮，一种截短的11-顺式视黄醛类似物，提高了中/长波长敏感的 （M/LWS）锥，但不是SWS 1锥。与假设一致，β紫罗兰酮是一种反向激动剂 对M/LWS视锥蛋白，但对SWS 1视锥蛋白的激动剂。这项建议旨在改善 所有视锥细胞类型在LCA 2小鼠模型中的存活， 仍然可以改善视力;识别可以使视锥细胞视蛋白失活的新化合物; 确保它们不会严重阻碍野生型小鼠的视力;并确定这些影响。 化合物对细胞培养物中视锥细胞视蛋白的运输和翻译后修饰的影响， 动物模型荧光显微镜、视网膜电图、质谱和生化分析 方法将用于评估测试化合物对视锥细胞存活、功能和视蛋白的影响。 特性.视蛋白反向激动剂的使用可能在改善光感受器中具有更广泛的适用性。 与受损的类维生素A处理相关的其他视觉问题的存活率， 视网膜色素变性和衰老。

Project Summary / Abstract The broad objective of this project is to understand the underlying events that lead to photoreceptor degeneration when problems with retinoid metabolism arise and to develop methods to prevent cones from degenerating. In Leber Congenital Amaurosis type 2 (LCA2), generation of the native chromophore of visual pigments (11-cis retinal) is inhibited. In mouse models for LCA2, cone cells die rapidly. Damage is most severe with short wavelength sensitive (SWS1) cones. This pattern roughly parallels the pathogenesis of LCA2. Studies from other laboratories have demonstrated that gene therapy can restore vision but appears limited by irreversible cone loss prior to the treatment. Early administration of an exogenous source of 11-cis retinal to mouse models improved cone survival, but recent work from this laboratory demonstrated that this was ineffective when mice were subjected to room light. These results suggest that (1) cone opsin/11-cis retinal interactions are important in preventing cone death, and (2) 11-cis retinal will not be the solution to treating LCA2 because normal light conditions negates its benefits. Because cone opsins are constitutively active but deactived with 11-cis retinal, the hypothesis for this project is that the increased levels of active cone opsins lead to cone degeneration in LCA2. Thus, light-insensitive small molecules that deactivate cone opsins will be protective to cone cells when endogenous 11-cis retinal is limited. Preliminary data indicate that beta ionone, a truncated analog of 11-cis retinal, improved survival of middle/long wavelength-sensitive (M/LWS) cones but not SWS1 cones. Consistent with the hypothesis, beta ionone is an inverse agonist to M/LWS cone opsins but an agonist to SWS1 cone opsins. This proposal aims to improve the survival of all cone types in mouse models for LCA2 such that reintroduction of the missing gene later in development can still improve vision; identify new compounds that can deactivate cone opsins; ensure that they will not severely impede vision in wild-type mice; and determine the impact of these compounds on trafficking of and post-translational modifications to cone opsins in cell culture and animal models. Fluorescence microscopy, electroretinography, mass spectrometry, and biochemicial methods will be used to assess the effects of test compounds on cone cell survival, function, and opsin properties. The use of opsin inverse agonists may have broader applicability in improving photoreceptor survival for other visual problems associated with compromised retinoid processing such as Stargardt's, retinitis pigmentosa, and aging.