Circadian Organization of the Retina

描述（由申请人提供）：脊椎动物视网膜普遍受昼夜节律的影响。在脊椎动物物种中有各种各样的视网膜节律，包括-杆和锥盘脱落；多巴胺和褪黑素合成；ERG b波振幅；还有视觉敏感度。我们研究的长期目标是阐明视网膜细胞类型和视网膜功能昼夜组织的关键机制。通过绘制昼夜节律钟基因Per 1在小鼠视网膜中的时空分布，利用转基因小鼠，其中转录Per 1的神经元被动态绿色荧光蛋白（GFP）报告标记，我们已经确定了Per 1时钟基因节律集中在视网膜内的神经元中，部分集中在多巴胺能无分泌细胞内。此外，McMahon实验室最近建立了转基因小鼠系，表达酪氨酸羟化酶（TH）基因转录的红色荧光蛋白（RFP）报告基因，以标记多巴胺能神经元。在这里，我们建议使用这些独特的小鼠模型进行功能研究，检查视网膜昼夜节律组织的三个关键方面：1 .表达多巴胺能无分泌细胞的Per 1的靶向电生理-我们将检查这些神经元是否在尖峰频率和离子电流中表现出内在的昼夜节律。2。多巴胺能无分泌细胞和光感受器在视网膜节律性中的作用-我们将确定这些细胞群是否支持视网膜生物钟基因表达的昼夜节律。3。表达Per 1的神经节细胞和神经节细胞节律性的表征-我们将确定表达Per 1的神经节细胞的功能类型（即ON， OFF, transient），以及神经节细胞活动是否具有节律性。这些目标的完成将对视网膜回路与环境条件相匹配的机制产生重要的见解，并为理解受视网膜生物钟及其褪黑激素/多巴胺输出影响的光感受器变性和近视的潜在机制提供扩展的基础。

DESCRIPTION (provided by applicant): The vertebrate retina is pervasively influenced by circadian (daily) rhythmicity. Across vertebrate species there is a wide variety of retinal rhythms including - rod and cone disc shedding; dopamine and melatonin synthesis; ERG b-wave amplitude; and visual sensitivity. The long-term goal of our research is to elucidate the retinal cell types and mechanisms critical for circadian organization of retinal function. By mapping the temporal and spatial distribution of the circadian clock gene Per 1 in the mouse retina, using transgenic mice in which neurons transcribing Per 1 are marked with a dynamic green fluorescent protein (GFP) reporter, we have established that Per 1 clock gene rhythms are concentrated in neurons of the inner retina, in part, within dopaminergic amacrine cells. In addition, the McMahon lab has recently established transgenic mouse lines which express a red fluorescent protein (RFP) reporter of tyrosine hydroxylase (TH) gene transcription to mark dopaminergic neurons. Here we propose to use these unique mouse models for functional studies examining three critical aspects of the circadian organization of the retina: I. Targeted Electophysiology of Per 1 - Expressing Dopaminergic Amacrine Cells - we will examine if these neurons exhibit intrinsic circadian rhythms in spike frequency and ionic currents. II. The Roles of Dopaminergic Amacrine Cells and Photoreceptors in Retinal Rhythmicity - we will determine if these cell populations support circadian rhythms in overall retinal clock-gene expression. III. Characterization of Per 1 - Expressing Ganglion Cells and Ganglion Cell Rhythmicity - we will determine the functional types of Per 1 - expressing ganglion cells (i.e. ON, OFF, transient), and whether ganglion cell activity is rhythmic. Completion of these aims will produce important insights into the mechanisms by which the retinal circuits match their performance to ambient conditions and provide an expanded basis for understanding the underlying mechanisms of photoreceptor degeneration and myopia, pathological eye conditions affected by the retinal circadian clock and its melatonin/dopamine outputs.