Photosensitive control of the inner retina

描述（由申请人提供）：我们建议将光敏性直接赋予病变视网膜中正常非光敏神经元。虽然遗传性视网膜变性有许多遗传原因，但一个共同的主题是光感受器细胞最终的凋亡死亡。在大多数情况下，在视杆细胞和视锥细胞丢失后，剩余的视网膜内神经元能存活很长时间。我们的核心目标是使用新型视紫红质，它可以用可见光精确地控制神经活动。通道视紫红质-2是一种光敏阳离子通道，允许神经兴奋以响应蓝光。一种功能上的逆转录物是Halorhodopsin，一种光敏氯离子泵，可以用黄光抑制神经活动。这些视紫红质使用类维甲酸作为它们的发色团，直接调节活性，而不需要辅助蛋白级联或外源化学物质。我们假设，如果在适当的细胞亚型中启动，光驱动的兴奋和抑制可能会重新创建正常存在于视网膜中的ON和off中心视觉信息流。这些并行信息流主要负责允许对比度灵敏度和高敏锐度。特异性递送到所需的ON或off中心细胞群不是微不足道的，我们建议通过结合转录靶向和病毒基因转移方法来解决这个问题。膜片钳电生理学结合光栅扫描刺激将是评估转基因靶向特异性和表征这些神经元网络产生的光电流的项目的组成部分。最后，我们希望了解在疾病模型中，光敏的内视网膜是否可以通过简单的行为工具将功能信息传递给更高的视觉中心。利用这些结合神经工程和电生理学的方法，我们的目标是确定选择性光激发和抑制ON和OFF通路内神经元是否可以赋予损伤视网膜有用的光敏感性。公共卫生相关性：基因治疗是一种非常有前途的方法，可以尝试在导致光感受器丧失的疾病中恢复视力，而直接将光敏性赋予存活的视网膜神经元可能是一种方法。我们希望了解将非光敏神经元转化为光敏神经元的潜力，并将这些知识应用于视网膜假肢的未来发展。

DESCRIPTION (provided by applicant): We propose to impart light sensitivity directly onto normally non-photosensitive neurons in a diseased retina. While inherited retinal degenerations have many genetic causes at their source, one common theme is the eventual apoptotic death of photoreceptor cells. In most cases, the remaining inner retinal neurons survive long after rods and cones are lost. Central to our goal is the use of novel rhodopsins that allow for precise optical control of neural activity with visible light. Channelrhodopsin-2 is a photosensitive cation channel that allows for neural excitation in response to blue light. A functional converse is Halorhodopsin, a photo- sensitive chloride pump that silences neural activity with yellow light. These rhodopsins use retinoids as their chromophore and directly modulate activity without accessory protein cascades or exogenous chemicals. We hypothesize that if initiated in the appropriate cell subtype, light-driven excitation and inhibition may re- create the ON and OFF-center visual information streams normally present in the retina. These parallel information streams are largely responsible for allowing contrast sensitivity and high acuity. Specific delivery to the desired ON or OFF-center cell population is not trivial, and we propose to approach this by a combination of transcriptional targeting along with viral gene transfer methods. Patch clamp electrophysiology combined with raster scanning stimuli will be integral to the project for both evaluating the specificity of transgene targeting and in characterizing the photocurrents generated from networks of these neurons. Finally, we hope to understand if a photosensitive inner retina can transmit functional information to higher visual centers in a disease model with simple behavioral tools. Using these combined neuroengineering and electrophysiological approaches, we aim to determine if selective photo-excitation and inhibition of ON and OFF pathway inner neurons can confer useful light sensitivity to the injured retina. PUBLIC HEALTH RELEVANCE: Gene therapy is a highly promising method for attempting to restore vision in diseases that cause photoreceptor loss, and imparting light sensitivity directly to surviving retinal neurons may be one approach. We hope to understand the potential for converting non-photosensitive neurons into photosensors and apply this knowledge toward the future development of a retinal prosthetic.