3D functional changes in the gap junctional signaling during the age related neurodegeneration in the mammalian inner ear Organ of Corti

哺乳动物内耳柯蒂氏器年龄相关神经变性过程中间隙连接信号的 3D 功能变化

• 批准号: MR/S006761/1
• 负责人: Snezana Levic
• 金额: $ 1.93万
• 依托单位: University of Sussex
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FS006761%2F1
• 关键词: 3D; functional; changes; gap; junctional

Hearing loss is one of the major health concerns worldwide. Over 50% of individuals older than 75 suffer from permanent hearing loss. Currently, there is no therapeutic agent that can prevent or reduce the progression of hearing loss. The main hallmark of hearing loss is the damage to the auditory inner ear, including loss of various cell types responsible for the process of hearing, such as spiral ganglion neurons, sensory hair cells and stria vascularis. However, functional alterations are observed in the specific cell types before the onset of hearing loss. These cells which show pathological changes before the onset of hearing are functionally coupled with gap junctions. Gap junctions are intercellular connections that directly connect the cytoplasm of two cells, and allow various molecules, ions and electrical impulses to directly pass through a regulated gate between cells. Importantly, alterations in gap junction function is the major cause of hereditary deafness in humans. Probing the role gap junctional intercellular communication in the process of hearing has relied on studies in expression systems and immature inner ear cultures, using invasive techniques which disrupt native cellular composition (such as injecting dyes into the cell to observe the propagation of dye between cells through gap junctions), or using techniques which cause the damage to the cells (such as very high intensity lasers which are used to visualize the dyes injected). In this study, we focus on mature native tissues, to study gap junctional coupling using novel, non-invasive techniques, allowing for preservation of cellular and endogenous metabolites and second messengers, which are established and important modulators of gap junctional signalling. Thus, this would be the first study to explore a direct link between the age related hearing loss and the alterations of gap junction signaling. The main objectives of this pilot study is to understand the functional alterations in the gap junction intercellular communication that contribute to neurodegeneration of the cochlea leading to hearing loss. We will use mice as models for the human cochlea. It has been shown that the mouse and human cochleae function in similar ways and share common underlying sensory processing mechanisms. Mice are most common animal model used for investigation of hearing processes and any possible hearing restoration. The studies of gap junctional coupling will be performed in acutely isolated auditory inner ear using novel high resolution optical techniques and cell permeable dyes which can defuse through gap junctions between cells to study the kinetics of gap junctional coupling. We will also use pharmacological modulators known to affect the gap junctional coupling and function to asses in intact system how these affect the electrical signalling between cells, and how they change in the process of neurodegeneration, such as in age related hearing loss. The results from this project may provide new directions and fresh opportunities to understand the process of hearing loss. Moreover, knowledge gained from these pilot studies would provide novel insights into the workings of cochlea and provide future research directions, which could ultimately contribute to development of future therapeutic treatments for the majority of the hearing impaired community that benefits very little from current treatments for hearing loss.

听力损失是全球主要的健康问题之一。超过50%的75岁以上的人患有永久性听力损失。目前，没有治疗剂可以预防或减少听力损失的进展。听力损失的主要标志是听觉内耳的损伤，包括负责听觉过程的各种细胞类型的损失，例如螺旋神经节神经元、感觉毛细胞和血管纹。然而，在听力损失发作之前，在特定细胞类型中观察到功能改变。这些细胞在听力开始前表现出病理变化，在功能上与间隙连接偶联。缝隙连接是直接连接两个细胞的细胞质的细胞间连接，并且允许各种分子、离子和电脉冲直接通过细胞之间的调节门。重要的是，间隙连接功能的改变是人类遗传性耳聋的主要原因。探索缝隙连接细胞间通讯在听觉过程中的作用依赖于表达系统和未成熟内耳培养物的研究，使用破坏天然细胞组成的侵入性技术（例如将染料注射到细胞中以观察染料通过间隙连接在细胞之间的传播），或使用对细胞造成损伤的技术（例如用于使注射的染料可视化的非常高强度的激光）。在这项研究中，我们专注于成熟的天然组织，研究间隙连接偶联使用新的，非侵入性的技术，允许保存细胞和内源性代谢产物和第二信使，这是建立和重要的调节器的间隙连接信号。因此，这将是第一个探索年龄相关性听力损失与缝隙连接信号改变之间直接联系的研究。本初步研究的主要目的是了解导致听力损失的耳蜗神经退行性变的差距连接细胞间通讯的功能改变。我们将使用小鼠作为人类耳蜗的模型。已经表明，小鼠和人类耳蜗以相似的方式起作用，并且共享共同的潜在感觉处理机制。小鼠是研究听力过程和任何可能的听力恢复的最常见的动物模型。本研究将在急性离体听性内耳中利用新型的高分辨光学技术和细胞可渗透性染料，通过细胞间的缝隙连接来研究缝隙连接耦合的动力学。我们还将使用已知影响差距连接耦合和功能的药理学调节剂来评估完整系统中这些调节剂如何影响细胞之间的电信号，以及它们在神经变性过程中如何变化，例如在与年龄相关的听力损失中。该项目的结果可能为了解听力损失的过程提供新的方向和新的机会。此外，从这些试点研究中获得的知识将为耳蜗的工作提供新的见解，并提供未来的研究方向，这最终可能有助于为大多数听力受损社区开发未来的治疗方法，这些社区从目前的听力损失治疗中获益甚少。