Molecular characterization of mouse melanopsin and second messenger pathway.

小鼠黑视蛋白和第二信使途径的分子特征。

• 批准号: 7656162
• 负责人: PHYLLIS R ROBINSON
• 金额: $ 31.98万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE COUNTY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-04-01 至 2013-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7656162
• 关键词: Arrestins; Behavior; Behavioral; Binding; Biochemical; Biochemical Pathway; Biochemistry; Biology; Blindness; Brain; Cell physiology; Cells; Characteristics; Circadian Rhythms; Data; Disease; Electrophysiology (science); Exhibits; Family; Family member; Future; G alpha q Protein; G-Protein-Coupled Receptors; GRK; GTP-Binding Proteins; Goals; Hour; Invertebrates; Light; Light Adaptations; Mass Spectrum Analysis; Mediating; Modification; Molecular; Molecular Genetics; Mouse Strains; Mus; Mutation; Natural regeneration; Nature; Neurodegenerative Disorders; Opsin; Pathway interactions; Peripheral; Pharmacological Treatment; Phospholipase C; Phosphorylation; Phosphotransferases; Photochemistry; Photoreceptors; Phototransduction; Physiological; Physiology; Pigments; Post-Translational Protein Processing; Property; Proteins; Research; Research Project Grants; Retina; Retinal; Retinal Cone; Retinal Ganglion Cells; Retinal Pigments; Reverse Transcriptase Polymerase Chain Reaction; Role; Second Messenger Systems; Sensory; Signal Pathway; Signal Transduction; Site; Site-Directed Mutagenesis; Sleep Disorders; Structure; Synapses; System; Testing; Transgenic Mice; Travel; Vertebrate Photoreceptors; base; behavior test; circadian pacemaker; design; experience; ganglion cell; in vitro Assay; in vivo; interdisciplinary approach; interest; light entrainment; melanopsin; member; novel; patch clamp; public health relevance; receptor; research study; response; second messenger; shift work; suprachiasmatic nucleus

DESCRIPTION (provided by applicant): Many aspects of mammalian physiology and behavior exhibit a daily 24 hour rhythm. These daily oscillations are circadian rhythms and are controlled by a brain structure known as the suprachiasmatic nucleus (SCN). The mammalian circadian clock is constantly being reset by the onset of environmental light. Light entrainment of the clock requires input from the retina, which communicates with the SCN via the axonal projections of a small subset of retinal ganglion cells (RGCs). Surprisingly, rod and cone photoreceptors are not required; instead, RGCs that project to the SCN appear to function as autonomous circadian photoreceptors as they exhibit light responses independent of rod- and cone-driven synaptic input. These SCN-projecting RGCs also express melanopsin, a novel vertebrate opsin, which is necessary for initiating the light response in these cells. Among all known vertebrate opsins, melanopsin is unique; it shows greater sequence similarity to invertebrate rhabdomeric photoreceptor opsins than to other vertebrate opsins. The current understanding of melanopsin's biochemical properties is rudimentary and its in vivo second messenger system has yet to be conclusively established and extensively characterized. The overall goal of the proposed research is to characterize the spectral and biochemical properties of melanopsin and to determine the biochemical pathway that mediates the intrinsic light responses of SCN-projecting RGCs. We hypothesize that melanopsin forms a photopigment that has biochemical characteristics similar to visual pigments associated with rhabdomeric photoreceptors and activates a Gq-based signaling pathway. Furthermore, we hypothesize that melanopsin undergoes light-dependent modifications that contribute to light adaptation of the melanopsin-dependent signaling cascade. To test these hypotheses, we propose an interdisciplinary approach combining biochemistry, electrophysiology, molecular genetics and behavioral studies. This approach is designed to determine melanopsin's photochemistry, to elucidate the nature of the second messenger pathway activated by melanopsin, and to determine if there are light-dependent post-translational modifications of melanopsin. PUBLIC HEALTH RELEVANCE: Many aspects of mammalian physiology and behavior exhibit a daily 24 hour rhythm. These daily oscillations are circadian rhythms and are controlled by a brain structure known as the suprachiasmatic nucleus. The mammalian circadian clock is constantly being reset by the onset of environmental light. Light entrainment of the clock requires input from the retina, which communicates with the suprachiasmatic nucleus via the axonal projections of a small subset of retinal ganglion cells. Surprisingly, classical photoreceptors, rods and cones are not necessary; instead, suprachiasmatic nucleus - projecting retinal ganglion cells function as autonomous photoreceptors. These ganglion cells also express a novel vertebrate visual pigment, known as melanopsin, which is necessary for initiating the light response in these cells. The proposed research project aims to characterize melanopsin. Understanding the signaling cascade activated by melanopsin is of great interest and significance for the field of sensory biology and circadian rhythms. In addition, disorders of the circadian system often accompany neurodegenerative diseases, sleep disorders, and blindness, and are more commonly experienced as a result of transmeridian travel and shift work. In the future, elucidation of the melanopsin-based signaling cascade should allow us to develop successful pharmacological treatments for these disorders.

描述（由申请人提供）：哺乳动物生理和行为的许多方面都表现出每天 24 小时的节律。这些日常振荡是昼夜节律，由称为视交叉上核（SCN）的大脑结构控制。哺乳动物的生物钟不断地随着环境光的出现而重置。时钟的光夹带需要来自视网膜的输入，视网膜通过一小部分视网膜神经节细胞 (RGC) 的轴突投影与 SCN 进行通信。令人惊讶的是，不需要杆状和锥状感光器；相反，投射到 SCN 的 RGC 似乎起到自主昼夜节律感光器的作用，因为它们表现出独立于视杆和视锥驱动的突触输入的光响应。这些 SCN 投射的 RGC 还表达黑视蛋白，这是一种新型脊椎动物视蛋白，它对于启动这些细胞的光反应是必需的。在所有已知的脊椎动物视蛋白中，黑视蛋白是独一无二的。与其他脊椎动物视蛋白相比，它与无脊椎动物弹状光感受器视蛋白具有更大的序列相似性。目前对黑视蛋白生化特性的了解还很初级，其体内第二信使系统尚未最终确定和广泛表征。本研究的总体目标是表征黑视蛋白的光谱和生化特性，并确定介导 SCN 投射 RGC 固有光响应的生化途径。我们假设黑视蛋白形成一种光色素，其生化特征类似于与弹状体光感受器相关的视觉色素，并激活基于 Gq 的信号通路。此外，我们假设黑视蛋白经历光依赖性修饰，有助于黑视蛋白依赖性信号级联的光适应。为了检验这些假设，我们提出了一种结合生物化学、电生理学、分子遗传学和行为研究的跨学科方法。该方法旨在确定黑视蛋白的光化学，阐明黑视蛋白激活的第二信使途径的性质，并确定黑视蛋白是否存在光依赖性翻译后修饰。公共卫生相关性：哺乳动物生理和行为的许多方面都表现出每天 24 小时的节律。这些日常振荡是昼夜节律，由称为视交叉上核的大脑结构控制。哺乳动物的生物钟不断地随着环境光的出现而重置。时钟的光夹带需要来自视网膜的输入，视网膜通过一小部分视网膜神经节细胞的轴突投射与视交叉上核进行通信。令人惊讶的是，经典的光感受器、视杆细胞和视锥细胞并不是必需的。相反，视交叉上核投射的视网膜神经节细胞起到自主感光器的作用。这些神经节细胞还表达一种新型脊椎动物视觉色素，称为黑视素，它是启动这些细胞中的光反应所必需的。拟议的研究项目旨在表征黑视蛋白。了解黑视蛋白激活的信号级联对于感觉生物学和昼夜节律领域具有重大意义和意义。此外，昼夜节律系统紊乱常常伴随神经退行性疾病、睡眠障碍和失明，并且更常见于跨子午线旅行和轮班工作。将来，对基于黑视蛋白的信号级联的阐明将使我们能够开发出针对这些疾病的成功的药物治疗方法。