Molecular mechanisms of photoreceptor disc morphogenesis

光感受器盘形态发生的分子机制

基本信息

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
项目类别：
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

项目摘要

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.

该提案解决了视觉中最基本的未解决问题之一：分子和细胞负责构建和维持脊椎动物感光细胞的感光细胞器的机制，外段。外节是一个纤毛结构，充满一堆圆盘膜，提供用于光捕获的巨大表面和包含构成光转导机制的蛋白质。光盘已更新为了抵消光线照射的不利影响，光盘更新的保真度至关重要维持感光器健康和正常视力。现在已经确定的是，每一个新的组织的形成椎间盘开始于由分支肌动蛋白网络扩张驱动的睫状质膜外翻其机制类似于运动细胞中板状伪足的形成。仍然完全未知的是分子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。查明这种机制是本应用程序的总体目标。我们最近的工作表明，这肌动蛋白网络由 WAVE 蛋白复合物成核，其独特的亚基组成专门适合执行此功能。因为 WAVE 复合物在上游信号通路和下游肌动蛋白网络，这为阐明负责周期性的整个机制打开了大门肌动蛋白在椎间盘形态发生位点的组装和分解。为了实现这一目标，我们将结合两个实验室的努力，将贡献独特的专业知识和两个互补的遗传模型改良动物：小鼠和爪蟾。我们提出的实验将研究肌动蛋白的调节细胞骨架动力学，包括活体光感受器中的细胞骨架动力学，由两类调节分子控制：小分子 GTP 酶和磷酸肌醇。阐明这些机制对于增进我们对基本原理的理解至关重要光感受器经常退化的光感受器细胞生物学和病理生物学机制与外节形态发生的缺陷有关。