Circadian Organization of the Retina

描述（申请人提供）：视网膜既是一个感觉器官，也是一个自我维持的神经生物钟。视网膜作为视觉的主要感觉器官，完成物理光刺激的转导和编码为神经信号的初始步骤，然后通过视神经将视觉和光信息传递给大脑的其他部分。视网膜内在生物钟通过有节奏的基因表达和多巴胺、褪黑素等调节性神经递质的有节奏释放，调节视网膜神经元和视网膜回路，将视网膜整体感觉功能塑造成高灵敏度的“白天”和高灵敏度的“夜晚”状态。虽然视网膜生物钟对视网膜生理和代谢有广泛的影响，但视网膜生物钟的潜在细胞和分子机制尚不清楚。本研究的长期目标是阐明哺乳动物视网膜生物钟的基本机制及其对视网膜感觉功能的控制。对于即将到来的奖励期，我们建议研究特定昼夜节律钟基因和细胞群在视网膜昼夜节律钟中的功能作用，以及视网膜时钟调节视网膜敏感性的机制。具体来说，我们建议研究以下问题：具体目标1：视网膜生物钟的分子组织。利用敲除核心生物钟基因Per1、Per2、Cry1、Cry2、clock和NPAS2的小鼠细胞系，我们将测试这些基因在小鼠视网膜生物钟中的功能作用。具体目标二。视网膜生物钟的细胞组织。利用单细胞发光成像和细胞特异性操作分子昼夜节律钟功能，通过携带核心时钟基因Bmal1的floxed等位基因和Cre重组酶的细胞特异性表达的小鼠系，我们将试图确定视网膜中的哪些细胞群是昼夜节律起搏器。具体目标三。视网膜功能的生物钟控制。使用分子遗传学方法，我们将测试哪些细胞和传递途径是关键的：(1)使用ERG对视网膜敏感性的昼夜节律控制，以及(2)视网膜时钟的光掺杂。完成这些目标将有助于深入了解包括人类在内的许多生物的视觉功能和灵敏度根据一天中的时间进行调节的潜在机制。这些发现将是理解正常视网膜功能的基础，视网膜作为一个模型生物钟系统，并有助于我们理解与光感受器变性和近视相关的临床相关昼夜节律和多巴胺能视网膜机制。

DESCRIPTION (provided by applicant): The retina is both a sensory organ and a self-sustained neural circadian clock. As the primary sensory organ for vision, the retina performs the initial steps of transduction and encoding of physical light stimuli into neural signals, and then transmits visual and photic information to the rest of the brain via the optic nerve. The intrinsic retinal circadian clock shapes overall retinal sensory function into high acuity "day" and high sensitivity "night" states by modulating retinal neurons and reconfiguring retinal circuits through rhythmic gene expression and rhythmic of release of modulatory neurotransmitters such as dopamine and melatonin. Although the retinal circadian clock exerts extensive influence over retinal physiology and metabolism, the underlying cellular and molecular mechanisms of the retinal circadian clock are not well understood. The long-term goal of the research proposed here is to elucidate the fundamental mechanisms of the mammalian retinal circadian clock and its control of retinal sensory function. For the upcoming award period we propose to examine the functional role of specific circadian clock genes and cell populations in the retinal circadian clock, as well as the mechanisms by which the retinal clock modulates retinal sensitivity. Specifically, we propose to examine the following issues: Specific Aim I: Molecular Organization of the Retinal Circadian Clock. Using mouse lines in which the core circadian clock genes Per1, Per2, Cry1, Cry2, Clock and NPAS2 are knocked out we will test the functional role of each of these genes in the mouse retinal circadian clock. Specific Aim II. Cellular Organization of the Retinal Circadian Clock. Using single-cell luminescence imaging and cell- specific manipulation of molecular circadian clock function via mouse lines carrying floxed alleles of the core clock gene Bmal1 and cell-specific expression of Cre recombinase, we will seek to determine which cell populations in the retina are circadian pacemakers. Specific Aim III. Circadian Clock Control of Retinal Function. Using molecular genetic approaches, we will test which cells and transmitter pathways are critical for: (1) circadian control of retinal sensitivity using the ERG, and (2) light entrainment of the retinal clock. Completion of these aims will provide insight into the underlying mechanisms by which visual function and sensitivity is modulated according to time of day in many organisms, including humans. These findings will be fundamental for understanding normal retinal function, the retina as a model biological clock system, and contribute to our understanding of clinically relevant circadian and dopaminergic retinal mechanisms associated with photoreceptor degeneration and myopia. PUBLIC HEALTH RELEVANCE: Our vision is different at different times of day because our retina works differently at different times of day. These functional daily rhythms are not simple responses to the daily light-dark cycle, but, as demonstrated by their persistence in constant darkness, they are the overt expression of an endogenous, self-sustained circadian clock in the retina that drives many rhythms in retinal physiology and metabolism. The retinal circadian clock adjusts retinal function, biasing it appropriately for day or night vision. In addition, the retinal clock imparts differential vulnerability to retinal light damage at different times of day, is altered in the blinding disease retinitis pigmentosa, and influences macular edema and the development of myopia. Increased understanding of the retinal circadian clock is important to understanding human vision and its preservation and to elucidating the mechanisms of this model neural circadian pacemaker.