Circadian Organization of the Retina

描述(申请人提供)：脊椎动物的视网膜普遍受到昼夜节律的影响。在脊椎动物物种中，视网膜节律多种多样，包括视杆和视锥视盘脱落；多巴胺和褪黑素的合成；ERG b波幅度；以及视觉敏感度。我们研究的长期目标是阐明视网膜细胞的类型和对视网膜功能的昼夜组织至关重要的机制。通过绘制生物钟基因PER-1在小鼠视网膜中的时间和空间分布，使用转基因小鼠，其中转录PER-1的神经元被动态绿色荧光蛋白(GFP)报告标记，我们已经建立了PER-1时钟基因节律集中在视网膜内的神经元，部分在多巴胺能无长突细胞内。此外，麦克马洪实验室最近建立了转基因小鼠品系，这些品系表达酪氨酸羟化酶(TH)基因转录的红色荧光蛋白(RFP)报告，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来研究视网膜昼夜节律组织的三个关键方面：I.表达PER 1的多巴胺能无长突细胞的靶向电生理学-我们将检查这些神经元是否在尖峰频率和离子电流方面表现出内在的昼夜节律。2.多巴胺能无长突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体是否支持整个视网膜时钟基因表达的昼夜节律。表达PER-1的神经节细胞的特征和节律性-我们将确定表达PER-1的神经节细胞的功能类型(即开、关、瞬时)，以及神经节细胞的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，并为理解光感受器退化和近视的潜在机制、受视网膜生物钟及其褪黑素/多巴胺输出影响的病理性眼部疾病提供更广泛的基础。

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.