Central Regulation of the Peripheral Visual System

描述(申请人提供)：每天，我们视网膜中的光敏感细胞，我们的光感受器，脱落并更新一部分光敏膜。然而，这个过程为什么会发生还不完全清楚；这对人类和动物的健康视力是必不可少的。事实上，视网膜退化发生在无法摆脱感光膜的突变大鼠身上。在大多数动物中，光敏膜的脱落受生物钟(昼夜节律)的调节，并由生物钟和/或光触发。然而，关于生物钟和光如何相互作用来触发和调节光敏膜的日常脱落和更新，人们知之甚少。马蹄蟹的侧眼长期以来一直是研究感光细胞膜脱落和更新的重要系统。它的光感受器在许多重要方面与人类的杆状光感受器相似。在目前获得资助的项目(R15EY13196)中，我们开发并测试了一个光与生物钟相互作用的模型，以调节每日瞬时光敏膜脱落。到目前为止，我们已经了解到，时钟通过cAMP依赖的蛋白激酶(PKA)刺激光感受器蛋白合成的下调，为视网膜的瞬时脱落和更新做好准备。这个竞争性的延续应用程序建议通过以下两个具体目标继续评估我们的模型：(1)。研究是否需要下调视觉arrestin的表达来启动侧眼的短暂性横纹脱毛(TRS)，以及是否需要肌动蛋白结合蛋白Myosin III来稳定黎明后白天针对TRS的横纹。(2)。确定PKA是否通过或与MAP激酶途径竞争，在TRS的侧眼八胺能预刺激期间减少光感受器蛋白质的合成。这位P.I.和他的本科生合作者将通过RNA干扰途径利用基因沉默来敲除蛋白质(arrestin和myosin III)的表达。我们的模型假设，时钟调节这些蛋白质的表达，可能还有其他蛋白质，通过适当地调节光敏膜的每日周转来维持健康的视力。公共卫生意义-使用与人类视网膜有许多相似之处的简单无脊椎动物视网膜对于开发翻译模型至关重要，该模型可用于推动研究，以防止由于日常光感受器外节周转失败而导致的视网膜退化和失明。让本科生参与生物医学研究，对于这个国家通过招募最聪明的年轻公民进入医学和生物医学研究，并培养新一代消息灵通的科学教师和大学教授来向公民提供信息来促进我们的公共健康的能力至关重要。

DESCRIPTION (provided by applicant): Everyday, the light-sensitive cells in our retinas, our photoreceptors, shed and renew a portion of their light-sensitive membrane. Why this process occurs is not completely understood, however; it is essential for healthy vision in humans and animals. In fact, retinal degeneration occurs in mutant rats unable to shed their photosensitive membrane. In most animals, shedding of the photosensitive membrane is regulated by a biological clock (circadian rhythm) and triggered by that clock and/or by light. Relatively little is known, however, about how the biological clock and light interact to trigger and regulate daily shedding and renewal of photosensitive membrane. The lateral eye of the horseshoe crab (Limulus) has long served as an important system for the study of photoreceptor membrane shedding and renewal. Its photoreceptors are similar in many important ways to human rod photoreceptors. In the currently funded project (R15 EY13196), we developed and tested a model for the interaction of light and the biological clock in the regulation of daily transient photosensitive membrane shedding. To date, we have learned that the clock primes the retina for transient shedding and renewal through cAMP-dependent protein kinase (PKA) stimulated downregulation of photoreceptor protein synthesis. This competing continuation application proposes to continue to evaluate our model through the following two specific aims: (1). Investigate whether downregulation of visual arrestin expression is required to prime the lateral eye for transient rhabdom shedding (TRS), and whether the actin-binding protein myosin III is required to stabilize the rhabdom against TRS during post-dawn daylight. (2). Determine whether PKA acts through, or in competition with, a MAP kinase pathway to decrease photoreceptor protein synthesis during octopaminergic priming of the lateral eye for TRS. The P.I. and his undergraduate student collaborators will use gene silencing through the RNA interference pathway to knockdown the expression of proteins (arrestin and myosin III). Our model hypothesizes that the clock regulates the expression of these proteins, and possibly others, to maintain healthy vision through proper regulation of daily turnover of the photosensitive membrane. Public Health Significance - The use of a simple invertebrate retina with many similarities to the human retina is critical to the development of translational models that can be used to drive research to prevent retinal degeneration and blindness caused by failures in daily photoreceptor outer segment turnover. Involving undergraduate students in biomedical research is critical to this Nation's ability advance our public health through recruitment of our brightest young citizens into medicine and biomedical research, and to produce new generations of well-informed science teachers and College professors to inform the Citizenry.