Thresholds, sites, and contributions of circuit compensation following rod photoreceptorloss in mature retina

成熟视网膜视杆细胞感光损失后电路补偿的阈值、部位和贡献

• 批准号: 9913554
• 负责人: Felice A Dunn
• 金额: $ 36.3万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-05-01 至 2024-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9913554
• 关键词: Ablation; Address; Affect; Afferent Neurons; Amacrine Cells; Axon; Cell Death; Cells; Cessation of life; Cone; Data; Degenerative Disorder; Dendrites; Event; Exhibits; Financial compensation; Functional disorder; Future; Generations; Genes; Genetic; Glutamates; Goals; Human; Impairment; Individual; Injury; Investigation; Knowledge; Light; Link; Measures; Mediating; Modeling; Molecular; Mus; Neurons; Output; Pathway interactions; Patients; Photons; Photoreceptors; Population; Prosthesis; Proteins; Public Health; Reaction; Research; Resolution; Retina; Rod; Signal Transduction; Site; Structure; Synapses; Visual; Visual system structure; Work; base; cell type; diphtheria toxin receptor; effective therapy; ganglion cell; in vivo; innovation; insight; knock-down; mouse model; neural circuit; neuron loss; neuronal circuitry; normal aging; novel; postsynaptic; quantum; response; retinal neuron; retinal rods; stem cells; tool

There is critical need to understand the causes, extent, and mechanisms of reactions to cell death so that effective treatments most appropriate for the state of the remaining circuit can be employed, and so that constructive compensation can be harnessed as a potential treatment in conditions where a portion of the circuit endures. Our long-term goal is to salvage neuronal circuits. Here, we will define the effects of controlled cell death on specific circuits, cell types, synapses, and proteins for the purpose of understanding the conditions that result in constructive (e.g., compensation through increasing synaptic gain) vs. destructive (e.g., aberrant spontaneous activity that corrupts signal) response. The mouse retina is an exceptional platform for this study because the primary sensory neurons, photoreceptors, can be manipulated under genetic control; cell types within specific circuits are identifiable and accessible; and the functional readout can be interpreted as visual sensitivity. We propose to ablate variable populations of rods in mature retina and determine the structural and functional effects on the primary rod bipolar cell pathway, the most sensitive retinal pathway: rods→rod bipolar cells→AII amacrine cells→ON cone bipolar cells→ON sustained alpha ganglion cells (abbr. ON alpha). ON alpha ganglion cells receive the greatest number of rod inputs, thus would be the most sensitive to rod loss. Our central hypothesis is that the retina has constructive reactions to input loss with the capacity to recover normal function up to an undefined threshold; beyond this threshold, destructive reactions begin. Unknown is this tipping point. Our preliminary data show that despite loss of half the rods, rod- mediated light responses in ON alpha ganglion cell spikes are comparable to control, suggesting compensation within the primary rod bipolar cell pathway. Thus, the premise is strong for constructive compensation within the retina following rod loss, and we will determine the induction parameters, sites, and contributions of this compensation to maintaining function in the following aims: (Aim 1) to determine the degree of input loss that induces constructive vs. destructive structural and functional changes, and (Aim 2) to locate the site(s) and mechanism(s) of compensation within a well-defined neural circuit. The approach is innovative for genetic control over the timing and degree of rod death; synaptic- and cell-type specific structural and functional investigation of a well-defined retinal circuit; and molecular tools to distinguish between cell ablation and synapse disassembly in triggering compensatory mechanisms. The results will be significant for (1) determining the degree of rod death that triggers the remaining circuit to undergo destructive or constructive responses, (2) identifying the sites and contributions of structural and functional compensation to maintaining retinal function, and (3) providing knowledge essential to the optimization and deployment of therapies to treat dysfunctional photoreceptors involving stem cells, genes, and prostheses, all of which rely on a stable retinal circuit and/or extensive knowledge of the state of the surviving retinal circuit.

迫切需要了解细胞死亡反应的原因、程度和机制，以便可以采用最适合剩余回路状态的有效治疗方法，并且可以在以下情况下利用建设性补偿作为潜在的治疗方法：我们的长期目标是挽救神经回路，在这里，我们将定义受控细胞死亡对特定回路、细胞类型、突触和蛋白质的影响，以了解导致这种情况的条件。建设性的（例如，通过增加突触增益进行补偿）与破坏性（例如破坏信号的异常自发活动）反应相比，小鼠视网膜是本研究的一个特殊平台，因为初级感觉神经元、光感受器可以在特定的细胞类型下进行操纵。电路是可识别和可访问的；并且功能读数可以解释为视觉敏感性，并建议消除成熟视网膜中不同的视杆细胞群，并确定对最敏感的初级视杆细胞通路的结构和功能影响。视网膜通路：视杆细胞→视杆双极细胞→AII无长突细胞→ON视锥双极细胞→ON持续α神经节细胞（简称ONα）接收最多数量的视杆细胞输入，因此对视杆细胞最敏感。我们的中心假设是，视网膜对输入损失有建设性的反应，并且有能力恢复正常功能，直到达到一个未定义的阈值；超过这个阈值，我们的初步数据表明，破坏性的反应就会开始。尽管失去了一半的杆，杆 ON α神经节细胞尖峰介导的光反应与对照相当，表明补偿 因此，在视杆细胞丧失后视网膜内进行建设性补偿的前提是强有力的，我们将确定这种补偿的诱导参数、部位和对维持功能的贡献，目的如下：（目标 1） ）确定引起建设性与破坏性结构和功能变化的输入损失程度，以及（目标 2）在明确的神经回路中定位补偿的位点和机制。该方法是创新的。用于基因控制时间和程度视杆细胞死亡的研究；明确的视网膜回路的突触和细胞类型特异性结构和功能研究；以及区分细胞消融和突触分解触发补偿机制的分子工具。触发剩余回路经历破坏性或建设性反应的视杆细胞死亡程度，（2）确定结构和功能补偿对维持视网膜功能的位置和贡献，以及（3）提供优化和部署治疗方法所必需的知识涉及干细胞、基因和假体的功能失调的光感受器，所有这些都依赖于稳定的视网膜回路和/或对幸存视网膜回路状态的广泛了解。