Light-activated ion chanenls for remote control of neuronal activity

描述(申请人提供)：神经元具有可被电压、配体、温度和机械力直接激活的离子通道，但不能被光激活。我们在这个项目中的目标是利用有机化学和分子生物学的结合来设计可以直接受光调节的新型离子通道。然后，我们将使用这些通道来回答有关视网膜中依赖活动的突触可塑性的问题，这些问题是目前可用的方法无法接近的。具体地说，这个项目将做出几个重大贡献。1)它将增加不断增长的光激活通道工具箱，这些通道对于远程控制神经元活动的不同方面非常有用。2)它将阐明视网膜神经节细胞是否像海马神经元一样表现出动态平衡突触可塑性，揭示视网膜中的突触是硬连接的还是可以随着使用而改变。3)它将阐明突触稳态是在树突状树的一部分内局部起作用，还是仅在整个神经元上起作用，从而为海马体和视网膜的稳态可塑性的功能重要性和机制提供线索。4)它将阐明由于视网膜色素变性小鼠和大鼠模型的光感受器退化而发生的视网膜回路的生理变化。通过阐明视网膜重塑的功能效应和时间进程，本研究将为评估和设计依赖于通过视网膜的完整突触信号的新的治疗策略提供关键重要的信息，包括用于恢复光感受器功能的基因治疗和用于再生视杆或视锥的干细胞治疗。与公共健康相关：在这个项目中，我们将设计新的分子，使神经细胞能够在光线下开启和关闭。我们将使用这些工具来回答重要的问题，即神经细胞之间的突触连接如何随着活动的变化而变化，以及在视杆和视锥在退行性致盲疾病(如视网膜色素变性)中丢失后，通过视网膜的信号如何变化。这将为了解视网膜如何运作和适应不同的光线条件提供基本信息，并将有助于设计和评估未来恢复视力的治疗策略。

DESCRIPTION (provided by applicant): Neurons possess ion channels that are directly activated by voltage, ligands, temperature, and mechanical forces, but not by light. Our goal in this project is to use a combination of organic chemistry and molecular biology to engineer new types of ion channels that can be directly regulated by light. We will then use these channels to answer questions focused on activity dependent synaptic plasticity in the retina that are unapproachable with presently available methods. Specifically, this project will make several major contributions. 1) It will add to the growing toolbox of light-activated channels that are of great utility for remote control of different aspects of neuronal activity. 2) It will elucidate whether retinal ganglion cells, like hippocampal neurons, exhibit homeostatic synaptic plasticity, revealing whether synapses in the retina are hard-wired or can change with use. 3) It will elucidate whether synaptic homeostasis operates locally within a portion of a dendritic tree, or only globally, across an entire neuron, providing clues as to the functional importance and mechanism of homeostatic plasticity in the hippocampus and retina. 4) It will elucidate the changes in the physiology of the retinal circuit that occur as a consequence of photoreceptor degeneration in mouse and rat models of retinitis pigmentosa. By elucidating the functional effects and time course of retinal remodeling, this study will provide information of key importance for evaluating and designing new therapeutic strategies that rely on intact synaptic signaling through the retina, including gene therapy for restoring photoreceptor function and stem cell therapy for regenerating rod or cones. PUBLIC HEALTH RELEVANCE: In this project we will engineer new molecules that will allow nerve cells to be turned on and off with light. We will use these tools to answer important questions about how synaptic connections between nerve cells change with activity and how signaling through the retina changes after rods and cones are lost during degenerative blinding diseases such as retinitis pigmentosa. This will provide fundamental information for understanding how the retina functions and adapts to different light conditions and will be useful for designing and evaluating future therapeutic strategies for restoring vision.