The roles of Gbeta5 and R7 RGS protein in vision

Gbeta5和R7 RGS蛋白在视觉中的作用

• 批准号: 8511667
• 负责人: Ching-Kang Jason Chen
• 金额: $ 28.71万
• 依托单位: VIRGINIA COMMONWEALTH UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-01 至 2014-01-24
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8511667
• 关键词: Adult; Affect; Amacrine Cells; Area; Biochemistry; Biological Preservation; Birth; Brain; Cell membrane; Cell physiology; Cells; Cellular Structures; Defect; Dendrites; Dendritic Cells; Development; Disease; Electron Microscopy; Electrophysiology (science); Electroretinography; Future; GTP-Binding Protein Regulators; GTP-Binding Proteins; Genes; Genetic; Goals; Heterotrimeric GTP-Binding Proteins; Histology; Human; Inherited; Investigation; Knock-in Mouse; Knock-out; Knowledge; Light; Link; Measures; Mediating; Membrane Potentials; Modality; Molecular Biology; Morphology; Mus; Mutation; Nature; Night Blindness; Partner in relationship; Patients; Photoreceptors; Phototransduction; Prevention; Property; RGS Proteins; Recovery; Regulation; Retina; Retinal; Retinal Diseases; Role; Signal Transduction; Staging; Synapses; System; Tamoxifen; Testing; Therapeutic; Time; Transgenic Mice; Vertebrate Photoreceptors; Vision; Visual; Visual system structure; Work; base; cholinergic; critical period; functional restoration; genetic manipulation; improved; insight; knowledge base; neurotransmission; novel; outer plexiform layer; patch clamp; postnatal; response; restoration; retinal neuron; retinal rods; retinogeniculate; ribbon synapse; synaptogenesis; vision development; visual information

DESCRIPTION (provided by applicant): Signal transduction mediated by heterotrimeric G-proteins occurs throughout nature and is best represented by phototransduction in retinal rods. However, how trimeric G-proteins subserve vertebrate vision outside photoreceptors is still poorly understood. This application will fill this gap by elucidating the roles of the fifth Gb subnit (Gb5) and its obligate partners R7 Regulators of G-protein Signaling (RGS6, RGS7, RGS9, RGS11) in mouse retina. The proposal is based on defects found in the visual system of Gb5-/-mice, which include: 1) infrequent spontaneous retinal waves~ 2) poorly refined retinogeniculate projections~ 3) abnormal ribbon synapses at outer plexiform layer (OPL) with unincorporated depolarizing bipolar cells (DBC) dendrites~ 4) lack of electroretinography (ERG) b-waves~ 5) reduction of starburst amacrine cell (SAC) dendritic field, 6) rhythmic oscillation SAC membrane potentials, and 7) prolonged phototransduction recovery. We demonstrate that Gb5 works exclusively through stabilizing R7 RGS proteins in retina and hence in its absence the signaling state of Gbo is hypothesized to be pathologically prolonged to cause these visual defects. Furthermore, we find that the requirement of Gb5 and R7 RGS for normal DBC function takes place during retinal development and that Gb5 may be very slowly turned over at dendritic tips of adult DBC. Solving the underlying mechanism(s) of the aforementioned defects will thus advance knowledge concerning the development and function of retina. We propose here to use an integrated approach combining molecular biology, biochemistry, histology, mouse genetics, ERG, and single cell electrophysiology to achieve the following goals. Aim-1 will test whether prolonged Gbo signaling retards formation of OPL triadic ribbon synapses in Gb5-/- mice. Aim-2 will define a critical period during which Gb5 and R7 RGS proteins are needed for visual system development. It will also measure the stability of OPL synapse and turnover rate of Gb5, Gbo, Gb13 and R7 RGS proteins in DBC. Aim- 3 will examine which and how R7 RGS proteins are involved in stage II cholinergic retinal waves, whether prolonged Gbo activation underlies the reduction of SAC dendritic fields, and the synaptic origin and oscillatory mechanism of adult Gb5-/- SAC. By completing these aims we shall know which and how trimeric G-proteins are used in vision beyond phototransduction in different retinal neurons. Useful mouse lines will be made here and characterized to facilitate future inquiry of the applicability of newly gained knowledge in the retina to central visual system and/or other CNS circuits. Finally, knowing the normal visual mechanism is indispensable for efficient prevention, preservation, and restoration of vision in patients suffering from various debilitating blinding diseases.

描述（由申请人提供）：由异源三聚体 G 蛋白介导的信号转导存在于自然界中，最好的代表是视网膜杆中的光转导。然而，三聚体 G 蛋白如何促进脊椎动物光感受器之外的视力仍然知之甚少。该应用将通过阐明小鼠视网膜中第五个 Gb 亚基 (Gb5) 及其 G 蛋白信号转导 R7 调节器 (RGS6、RGS7、RGS9、RGS11) 的作用来填补这一空白。该提议基于在 Gb5-/-小鼠视觉系统中发现的缺陷，其中包括：1）不常见的自发性视网膜波~2）细化的视网膜原状投影~3）外丛状层（OPL）处的异常带状突触具有未结合的去极化双极细胞 (DBC) 树突~ 4) 缺乏视网膜电图 (ERG) b 波~ 5) 星爆减少无长突细胞 (SAC) 树突状区域，6) 节律振荡 SAC 膜电位，7) 延长光转导恢复。我们证明 Gb5 仅通过稳定视网膜中的 R7 RGS 蛋白发挥作用，因此假设在其缺失的情况下，Gb5 的信号传导状态会病理性延长，从而导致这些视觉缺陷。此外，我们发现在视网膜发育过程中，正常 DBC 功能需要 Gb5 和 R7 RGS，并且 Gb5 在成人 DBC 的树突尖端可能非常缓慢地转换。因此，解决上述缺陷的根本机制将增进有关视网膜发育和功能的知识。我们在此建议采用分子生物学、生物化学、组织学、小鼠遗传学、ERG和单细胞电生理学相结合的综合方法来实现以下目标。 Aim-1 将测试延长的 Gbo 信号传导是否会阻碍 Gb5-/- 小鼠中 OPL 三元带状突触的形成。 Aim-2 将定义视觉系统发育需要 Gb5 和 R7 RGS 蛋白的关键时期。它还将测量 OPL 突触的稳定性以及 DBC 中 Gb5、Gbo、Gb13 和 R7 RGS 蛋白的周转率。 Aim-3 将研究哪些 R7 RGS 蛋白以及如何参与 II 期胆碱能视网膜波，长时间的 Gbo 激活是否是 SAC 树突域减少的基础，以及成人 Gb5-/- SAC 的突触起源和振荡机制。通过完成这些目标，我们将了解哪些三聚体 G 蛋白以及如何在不同视网膜神经元的光转导之外的视觉中使用。此处将制作有用的小鼠线并对其进行表征，以方便将来探究视网膜中新获得的知识对中央视觉系统和/或其他中枢神经系统回路的适用性。最后，了解正常的视觉机制对于有效预防、保存和恢复患有各种致盲性疾病的患者的视力是必不可少的。