Expression & function of channelrhodopsins in the retina

描述(申请人提供)：许多人类视网膜退行性疾病中的视力丧失或失明，如视网膜色素变性和年龄相关性黄斑变性，都是光感受器细胞退化的结果。目前，盲人还没有真正的治疗或治愈方法。目前大多数试图开发治疗失明疾病的方法都基于两种策略：一种是将正常细胞或干细胞移植到患病的视网膜中，另一种是通过视网膜植入物提供电刺激。我们提出了一种新的策略，旨在为患有感光细胞变性的盲人恢复一定程度的视力。我们的策略是使光感受器退行性视网膜中剩余的二级或三级神经元通过在其膜上表达光门通道来对光做出反应。这一战略很可能在机制和技术上都是可行的，可以避免当前办法遇到的许多障碍。特别是，最近克隆了直接光门微型视紫红质，通道红光双链蛋白，并在哺乳动物细胞系中进行了功能表达。在盲人患者和动物模型中的研究表明，视网膜的二级和三级神经元部分地保存在病变的视网膜中。此外，通过基因治疗将外源基因导入视网膜神经元也是可能的。这项建议的目的是在啮齿动物模型中对这一策略进行可行性研究。我们将在这个方案中检验的具体假设是：1)直接光门通道视紫红质可以在哺乳动物的视网膜神经元中表达，2)在感光细胞退化的视网膜中剩余的视网膜二级和三级神经元保持其传递和处理视觉信号的生理能力。这些研究将为进一步的工作奠定基础，从而开发一种潜在有效的治疗失明疾病的方法，以及在生物医学研究中具有宝贵应用价值的技术。

DESCRIPTION (provided by applicant): Vision loss or blindness in many human retinal degenerative diseases, such as retinitis pigmentosa and age-related macular degeneration, is a result of the degeneration of photoreceptor cells. At present, there is no real treatment or cure for the blind. Most of the current approaches that are attempting to develop treatments for the blinding disorders are based on two strategies: one involves transplantation of normal or stem cells into the diseased retinas and the other provides electrical-stimulation via retinal implants. We propose a new strategy that aims to restore a certain level of vision for the blind suffering from photoreceptor degeneration. Our strategy is to enable the remaining second or third order neurons in photoreceptor degenerative retinas to respond to light by expressing light-gated channels in their membranes. This strategy is likely to be feasible both mechanistically and technically and can avoid many obstacles encountered by the current approaches. Particularly, directly light-gated micro-type rhodopsins, channelrhodipsins, have been recently cloned and functionally expressed in mammalian cell lines. Studies in blind patients and in animal models suggest that the second and third order retinal neurons remain, in part, preserved in the diseased retinas. Furthermore, it is possible that exogenous genes can be introduced into retinal neurons by means of gene therapy. The objective of this proposal is to conduct feasibility studies for this strategy in rodent models. The specific hypotheses that we will test in this proposal are: 1) directly light-gated channelrhodopsins can be functionally expressed in mammalian retinal neurons, 2) the remaining retinal second and third order neurons in the photoreceptor-degenerative retinas retain their physiological capacity to relay and process visual signals. These studies will establish a foundation for further work leading to the development of a potentially effective treatment for the blinding disorders as well as techniques with valuable applicability in biomedical research.