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每天24小时节奏。这些日常振荡是昼夜节律，由称为脑部核（SCN）的大脑结构控制。哺乳动物昼夜节律的时钟不断地通过环境光的发作重置。时钟的光夹带需要视网膜的输入，该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通信。令人惊讶的是，不需要杆和锥形光感受器；取而代之的是，将SCN投影的RGC在表现出独立于杆和锥体驱动的突触输入的光反应时，似乎充当自动圆形光感受器。这些SCN投射RGC还表达了一种新型脊椎蛋白，这是在这些细胞中启动光反应所必需的。在所有已知的脊椎动物蛋白酶中，黑色素蛋白都是独一无二的。与其他脊椎动物蛋白相比，它显示出与无脊椎动物横纹肌光感受器Opsin的更大序列相似性。当前对黑色素蛋白生化特性的理解是基本的，其体内第二质体系统尚未得到最终确定和广泛的特征。拟议的研究的总体目标是表征黑色素蛋白的光谱和生化特性，并确定介导SCN射击RGC的内在光反应的生化途径。我们假设黑色素蛋白形成一种具有类似于与横纹肌光感受器相关的视觉颜料的生化特性并激活基于GQ的信号通路。此外，我们假设黑色素蛋白经历了光依赖性修饰，这有助于依赖黑色素蛋白依赖性信号传导级联的光适应。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。这种方法旨在确定黑色素蛋白的光化学，以阐明黑色素蛋白激活的第二信使途径的性质，并确定黑色素蛋白的光后翻译后修饰。公共卫生相关性：哺乳动物生理和行为的许多方面每天24小时节奏。这些日常振荡是昼夜节律，由称为脑部核的大脑结构控制。哺乳动物昼夜节律的时钟不断地通过环境光的发作重置。时钟的光夹带需要视网膜的输入，该视网膜通过一小部分视网膜神经节细胞的轴突投影与上核交流。令人惊讶的是，不需要经典的光感受器，棒和锥。取而代之的是，肌发作核 - 投射视网膜神经节细胞充当自主感光体。这些神经节细胞还表达了一种新型的脊椎动物视觉色素，称为黑色素蛋白，这对于启动这些细胞的光反应是必不可少的。拟议的研究项目旨在表征黑色素蛋白。了解黑色素蛋白激活的信号传导级联对于感觉生物学和昼夜节律领域具有极大的兴趣和意义。此外，昼夜节律系统的疾病通常伴随着神经退行性疾病，睡眠障碍和失明，并且由于跨性别的旅行和转移工作而更常见。将来，阐明基于黑色素的信号传导级联应使我们能够为这些疾病开发成功的药理治疗方法。