Molecular mechanisms of photoreceptor disc morphogenesis

光感受器盘形态发生的分子机制

• 批准号: 10749286
• 负责人: Vadim Y Arshavsky
• 金额: $ 65.5万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-30 至 2028-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10749286
• 关键词: Actins; Address; Adverse effects; Behavior; Biology; Biophysics; Cell membrane; Cells; Cellular biology; Cilia; Complement; Complex; Cytoskeleton; Defect; Electron Microscopy; Etiology; Fluorescence Microscopy; Frequencies; Functional Imaging; Functional disorder; Future; Genes; Genetically Modified Animals; Goals; Guanosine Triphosphate Phosphohydrolases; Health; Image; Impairment; Knock-out; Laboratories; Light; Maintenance; Mammals; Mass Spectrum Analysis; Mediating; Membrane; Metabolism; Methodology; Modeling; Molecular; Monomeric GTP-Binding Proteins; Morphogenesis; Mus; Organelles; Performance; Periodicals; Periodicity; Phosphatidylinositols; Phosphoric Monoester Hydrolases; Phosphotransferases; Photoreceptors; Phototransduction; Polymers; Positioning Attribute; Process; Protein Dephosphorylation; Proteins; Rana; Regulation; Research; Role; Signal Pathway; Site; Structure; Structure of retinal pigment epithelium; Surface; Therapeutic Intervention; Time; Transgenic Mice; Transgenic Organisms; Vertebrate Photoreceptors; Vision; WAVE protein; Work; Xenopus; base; cell motility; cell type; depolymerization; disorder prevention; experimental study; fascinate; inherited retinal degeneration; light adverse effect; light microscopy; phosphoinositide-3,4,5-triphosphate; photoreceptor cell outer segment; photoreceptor degeneration; photoreceptor disc; polymerization; programs; protein complex; recruit; sensor

This proposal addresses one of the most fundamental unsolved problems in vision: the molecular and cellular mechanism responsible for building and maintaining the light-sensitive organelle of vertebrate photoreceptor cells, the outer segment. The outer segment is a ciliary structure filled with a stack of disc membranes, which provide vast surfaces for light capture and harbor proteins comprising the phototransduction machinery. Discs are renewed on a daily basis in order to counteract the adverse effects of light exposure, and the fidelity of disc renewal is critical for maintaining photoreceptor health and normal vision. It is now well-established that the formation of each new disc begins with an evagination of the ciliary plasma membrane driven by an expansion of branched actin network in a mechanism akin the formation of lamellipodia in motile cells. What remain entirely unknown are the molecular mechanism that initiate the formation of each new disc with the striking periodicity of approximately 80 times per day in mammals. Pinpointing this mechanism is the overall goal of this application. Our recent work shows that this actin network is nucleated by the WAVE protein complex whose unique subunit composition is specifically fitted to perform this function. Because WAVE complexes mediate between the upstream signaling pathways and downstream actin networks, this opens doors to elucidating the entire mechanism responsible for the periodic assembly and disassembly of actin at the disc morphogenesis site. To accomplish this goal, we will combine the efforts of two laboratories, which will contribute unique expertise and two complementary models of genetically modified animals: mice and Xenopus frogs. Our proposed experiments will investigate the regulation of the actin cytoskeleton dynamics, including that in living photoreceptors, by two classes of regulatory molecules: small GTPases and phosphoinositides. Elucidating these mechanisms is critical for advancing our understanding of basic photoreceptor cell biology and pathobiological mechanisms underlying photoreceptor degeneration frequently associated with defects in outer segment morphogenesis.

这项提议解决了视觉中最基本的未解决的问题之一：分子和细胞 负责构建和维持脊椎动物感光细胞的光敏细胞器的机制， 外段。外节是充满一叠椎间盘膜的纤毛结构， 用于光捕获的广阔表面和包含光转导机制的蛋白质的港湾。光盘更新 以抵消光暴露的不利影响，并且光盘更新的保真度是至关重要的 维持感光细胞健康和正常视力。现在已经确定，每一个新事物的形成 盘开始于由分支肌动蛋白网络的扩张驱动的睫状质膜的外翻 其机制类似于运动细胞中片状伪足的形成。仍然完全未知的是 启动每个新圆盘形成的机制，每个新圆盘的撞击周期约为80次， 哺乳动物的一天精确定位此机制是此应用程序的总体目标。我们最近的研究表明， 肌动蛋白网络由WAVE蛋白复合物成核，WAVE蛋白复合物的独特亚基组成特别适合于 执行这个功能。由于WAVE复合物介导上游信号通路， 下游肌动蛋白网络，这打开了大门，阐明整个机制负责周期性 肌动蛋白在椎间盘形态发生部位的组装和分解。为了实现这一目标，我们将联合收割机 两个实验室的努力，这将有助于独特的专业知识和两个互补的模式，遗传 改良动物：老鼠和非洲爪蟾蛙。我们提出的实验将研究肌动蛋白的调节 细胞骨架动力学，包括在活的光感受器，由两类调节分子：小 GTP酶和磷酸肌醇。阐明这些机制对于促进我们对基本的 光感受器细胞生物学和光感受器变性背后的病理生物学机制经常 与外节形态发生缺陷有关。