Expression & function of channelrhodopsins in the retina

描述（由申请人提供）：许多人类视网膜退行性疾病的视力丧失或失明，如视网膜色素变性和年龄相关性黄斑变性，是光感受器细胞退化的结果。目前，盲人还没有真正的治疗方法或治愈方法。目前大多数治疗致盲性疾病的方法都是基于两种策略：一种是将正常细胞或干细胞移植到病变视网膜中，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，旨在为盲人恢复一定程度的视力遭受光感受器退化。我们的策略是使光感受器退行性视网膜中剩余的第二或第三阶神经元通过在其膜上表达光门控通道来对光做出反应。这一战略很可能在机械和技术上都是可行的，并且可以避免目前方法遇到的许多障碍。特别是，直接光门控微型红紫红质，通道红紫红质，最近被克隆并在哺乳动物细胞系中功能表达。对失明患者和动物模型的研究表明，第二和第三级视网膜神经元部分保留在病变视网膜中。此外，外源基因有可能通过基因治疗的方式导入视网膜神经元。本提案的目的是在啮齿动物模型中进行该策略的可行性研究。我们将在本提案中测试的具体假设是：1)直接光门控通道视紫红质可以在哺乳动物视网膜神经元中功能性表达；2)光感受器退行性视网膜中剩余的视网膜二级和三级神经元保留了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，从而开发潜在有效的致盲疾病治疗方法以及在生物医学研究中具有宝贵适用性的技术。

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.