An unexpected role of glutamate receptors in the peripheral nervous system

谷氨酸受体在周围神经系统中的意想不到的作用

• 批准号: 10570182
• 负责人: Bo Duan
• 金额: $ 51.31万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-05-15 至 2025-02-28
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10570182
• 关键词: Address; Afferent Neurons; Animals; Behavior; Behavioral; Biology; Caenorhabditis elegans; Calcium; Candidate Disease Gene; Categories; Cells; Central Nervous System; Chemicals; Cues; Data; Detection; Electrophysiology (science); Environment; Esthesia; Family; Fishes; Functional disorder; Generations; Genetic; Genetic Models; Genetic Screening; Glutamate Receptor; Glutamates; Homologous Gene; Human; Image; Inflammatory; Ion Channel Gating; Knockout Mice; Life; Mammals; Mediating; Molecular; Molecular Genetics; Mus; N-terminal; Nematoda; Neurons; Neuropathy; Peripheral; Peripheral Nervous System; RNA Interference; Research; Role; Sensory; Sensory Receptors; Signal Transduction; Synapses; System; Temperature; Temperature Sense; Testing; Time; Work; allodynia; cold temperature; conditional knockout; design; insight; interdisciplinary approach; kainate; knock-down; model organism; mutant; nervous system disorder; neuromechanism; novel; receptor; response; screening; sensor; tool; transmission process

The ability to sense environmental temperature is essential for life. Molecular thermal sensors are a central player in thermosensation. These thermal receptors are expressed in cold-sensitive neurons/cells in the periphery. Work in the past two decades has identified a large number of TRP family channels as heat receptors that sense a full range of warm and hot temperatures, spanning from 33°C to over 53°C. This has led to a fairly clear understanding of how animals sense heat. By contrast, little is known about cold sensation. Thus far, only one cold receptor (TRPM8) has been identified. TRPM8 senses cool temperatures with an activation threshold at ~26°C and mediates cool sensation. As animals and humans are clearly capable of sensing temperatures below 26°C, and TRPM8 knockout mice show robust responses to noxious cold, unknown cold receptors, particularly those sensing noxious cold, must exist but remain to be identified. The nematode C. elegans is a popular genetic model organism for sensory biology research. Like mammals, C. elegans senses a full range of temperature cues. Importantly, sensory receptors and channels tend to be evolutionarily conserved in C. elegans. This, together with its short generation time (~3 days) and facile and rich genetic tools, makes C. elegans an ideal system for identifying novel cold receptors. We therefore designed and conducted an unbiased, activity-based genetic screen for cold-sensing mutants in C. elegans, using a real-time PCR thermocycler. We identified GLR-3, a kainate-type glutamate receptor homolog, as a novel type of cold receptor that mediates cold sensation in C. elegans. Strikingly, the GLR-3 homolog GluK2 from fish, mouse and human can all function as a cold receptor in heterologous systems. We also found that mouse GluK2 is expressed in the peripheral DRG sensory neurons. The activation threshold of GluK2 is below 20°C, suggesting that it mainly senses noxious cold rather than cool temperatures. As glutamate receptors are best known to transmit chemical signals across synapses in the central nervous system, these results present a striking case where a central chemical receptor, surprisingly, functions as a thermal receptor in the periphery. Despite these exciting observations, many unanswered questions remain, particularly regarding the role of mammalian GluK2 in cold sensation. For example, does GluK2 mediate cold sensation in mice? If so, how? Here, we propose to address these questions by testing several hypotheses. To do so, we will leverage the expertise from two research groups using a multidisciplinary approach combining molecular genetics, behavioral analysis, calcium imaging, and electrophysiology. The proposed research will not only provide novel insights into the mechanisms of cold sensation, but also unveil an unexpected role of glutamate receptors in the periphery. .

感知环境温度的能力对生命至关重要。分子热传感器是 在温度感知中扮演重要角色这些热感受器表达于脑中的冷敏感神经元/细胞中。 外围。在过去二十年的工作已经确定了大量的TRP家庭渠道作为热 感受器可以感受到从33°C到53°C以上的各种温暖和高温。这导致 对动物如何感知热量有了相当清晰的了解。相比之下，对冷感觉知之甚少。 迄今为止，只有一种冷受体（TRPM 8）被确定。TRPM 8通过一个 激活阈值约为26°C，并介导凉爽感觉。因为动物和人类显然有能力 TRPM 8基因敲除小鼠对寒冷的反应非常强烈， 未知的冷感受器，特别是那些感受有害冷的感受器，一定存在，但仍有待鉴定。的 线虫C.线虫是一种流行的用于感觉生物学研究的遗传模式生物。与哺乳动物一样，C. 秀丽线虫能感知到各种温度信号重要的是，感觉受体和通道往往是 进化保守。优美的这一点，连同其短的世代时间（~3天）和轻便， 丰富的遗传工具，使C. elegans是鉴定新型冷受体的理想系统。因此我们 设计并进行了一个公正的，基于活动的遗传筛选冷敏感突变体在C。优雅， 使用实时PCR热循环仪。我们鉴定了GLR-3，一种红藻氨酸型谷氨酸受体同源物， 一种新型的冷感受器，介导C.优雅的引人注目的是，GLR-3同系物GluK 2 来自鱼、小鼠和人的冷受体在异源系统中都可以起冷受体的作用。我们还发现 小鼠GluK 2在外周DRG感觉神经元中表达。GluK 2的激活阈值低于 20°C，这表明它主要感受有害的寒冷，而不是凉爽的温度。就像谷氨酸受体 最为人所知的是通过中枢神经系统的突触传递化学信号，这些结果表明， 这是一个惊人的例子，令人惊讶的是，中央的化学感受器，在外围起到了热感受器的作用。 尽管有这些令人兴奋的观察结果，但仍然存在许多未回答的问题，特别是关于 哺乳动物GluK 2在冷感觉中的作用。例如，GluK 2是否介导小鼠的冷感觉？如果是，如何做到？ 在这里，我们建议通过测试几个假设来解决这些问题。为此，我们将利用 来自两个研究小组的专业知识，使用多学科方法结合分子遗传学， 行为分析钙成像和电生理学这项研究不仅提供了新的 深入了解冷感觉的机制，而且还揭示了谷氨酸受体在 外围。 .