Use of SyCatCh for the restoration of light signals in the retina of mice with photoreceptor degeneration

使用 SyCatCh 恢复光感受器变性小鼠视网膜中的光信号

• 批准号: 267355644
• 负责人: Dr. Michaela Fuchs
• 金额: --
• 依托单位: School of Life Sciences
• 依托单位国家: 德国
• 项目类别: Research Fellowships
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2015-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/267355644?language=en
• 关键词: Use; SyCatCh; restoration; light; signals

The retina is the first stage in the processing of light signals in the visual system. Highly specialized light-sensing neurons, the rod and cone photoreceptors, convert light into neural signals and transmit these to the post-receptoral retinal network. The retina performs considerable processing and filtering of the visual information before these signals are transmitted to the higher visual centers in the brain.Many retinal degenerative diseases involve the degeneration of photoreceptors and often lead to complete blindness. The prevention of vision loss or even the restoration of visual function are important goals in vision research. A promising strategy for the restoration of vision is optogenetics, which involves the introduction of genes encoding light-sensitive proteins (like channelrhodopsins) into neurons downstream of the photoreceptors. Upon light stimulation, these proteins generate electrical signals in neurons which are not intrinsically light-sensitive.The rd1 mouse is a widely used model of early onset retinal degeneration. It was previously demonstrated that expression of channelrhodopsin-2 in inner retinal cells of these mice can restore photosensitivity at the retinal and cortical level, proving the potential use of optogenetics in the restoration of vision. However, very high light intensities were needed for stimulation, which could ultimately cause photodamage to the retina. This might be overcome by using genetically engineered variants with altered properties.Our aim is to test a new optogenetic strategy for restoring light-sensitivity to the retinal circuitry following photoreceptor degeneration. This strategy is based on specifically controlling synaptic activity by light, by virally introducing the light-activated calcium channel CatCh into synaptic terminals of ON bipolar cells.Stimulation with blue light should lead to an influx of calcium ions and directly result in vesicle fusion at the highly specialized bipolar cell ribbon synapse, both of which we will measure using genetically encoded reporters of synaptic activity in combination with multiphoton imaging. We will use electrophysiological recordings with multi-electrode arrays to test whether the light signals are transmitted to the ganglion cells to generate spikes. All this will tell us directly how well CatCh expression in ON bipolar cells restores synaptic transmission in the retina of rd1 mice. We will test whether the light signals are transmitted to the higher visual centers in the brain by measuring optomotor responses and by imaging neural activity in the visual cortex.With our approach we will hopefully be able to restore visual function in mice with photoreceptor degeneration. We think that using CatCh will require significantly reduced light levels for activation of ON bipolar cells in comparison with previously used channelrhodopsins, thereby eliminating the concern that high intensity light induces photodamage in the retina.

视网膜是视觉系统中处理光信号的第一阶段。高度特化的感光神经元，视杆和视锥光感受器，将光转换成神经信号并将这些信号传递到后感受器视网膜网络。视网膜对视觉信息进行了大量的处理和过滤，然后将这些信息传输到大脑中的高级视觉中心。许多视网膜退行性疾病涉及光感受器的变性，并且通常导致完全失明。预防视力丧失甚至恢复视功能是视觉研究的重要目标。光遗传学是恢复视力的一个有希望的策略，它涉及将编码光敏蛋白（如通道视紫红质）的基因引入光感受器下游的神经元中。在光刺激下，这些蛋白质在本质上不对光敏感的神经元中产生电信号。rd 1小鼠是一种广泛使用的早发性视网膜变性模型。先前证明，这些小鼠的视网膜内细胞中通道视紫红质-2的表达可以恢复视网膜和皮质水平的光敏性，证明了光遗传学在视力恢复中的潜在用途。然而，刺激需要非常高的光强度，这最终可能导致视网膜的光损伤。我们的目的是测试一种新的光遗传学策略，用于恢复感光细胞变性后视网膜回路的光敏感性。这种策略是基于通过光特异性地控制突触活动，通过将光激活的钙通道CatCh病毒性地引入ON双极细胞的突触末端。蓝光刺激应导致钙离子的流入并直接导致高度特化的双极细胞带状突触处的囊泡融合，我们将使用遗传编码的突触活动报告基因结合多光子成像来测量这两种情况。我们将使用多电极阵列的电生理记录来测试光信号是否被传输到神经节细胞以产生尖峰。所有这些将直接告诉我们，ON双极细胞中CatCh的表达如何恢复rd 1小鼠视网膜中的突触传递。我们将通过测量视运动反应和成像视觉皮层的神经活动来测试光信号是否被传输到大脑中的高级视觉中心。通过我们的方法，我们将有望恢复感光细胞退化小鼠的视觉功能。我们认为，与以前使用的通道视紫红质相比，使用CatCh将需要显著降低的光水平来激活ON双极细胞，从而消除了高强度光诱导视网膜光损伤的担忧。