Purinergic signaling in taste buds

味蕾中的嘌呤信号

• 批准号: 8677871
• 负责人: Sue C. Kinnamon
• 金额: $ 32.94万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-01 至 2017-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8677871
• 关键词: Ablation; Address; Affect; Afferent Neurons; Amiloride; Applications Grants; Basal Cell; Behavior; Behavioral; Behavioral Assay; Biological Assay; Brain; Breeding; Canned Foods; Cells; Cellular Assay; Chemicals; Connexins; Data; Development; Discrimination; Disease; Doxycycline; Eating; Elements; Epithelial Cells; Esthesia; Exons; Fiber; Genetic; Genetic Models; Health; Housing; In Vitro; Knock-out; Knockout Mice; Laboratory mice; Lead; Link; Luciferases; Measures; Mediating; Medicine; Membrane; Modeling; Mus; NTPDase2; Nerve; Nerve Fibers; Nervous system structure; Neuroglia; Neurosciences; Non-Insulin-Dependent Diabetes Mellitus; Obesity; P2X-receptor; Pharmaceutical Preparations; Pharmacologic Substance; Phenocopy; Phenotype; Pilot Projects; Play; Poison; Population; Process; Purinoceptor; Receptor Signaling; Role; Shapes; Signal Transduction; Sodium Chloride; Stimulus; Supporting Cell; System; Taste Buds; Taste Perception; Testing; Time; Tissues; Type I Epithelial Receptor Cell; Type II Epithelial Receptor Cell; Type III Epithelial Receptor Cell; afferent nerve; cell type; compliance behavior; desensitization; ecto-nucleotidase; ectoATPase; in vitro testing; in vivo; inhibitor/antagonist; luciferin; neurophysiology; neurotransmitter release; postsynaptic; prevent; receptor; recombinase; relating to nervous system; research study; response; salt sensitive; transmission process

DESCRIPTION (provided by applicant): While substantial progress has been made in identifying the receptors and downstream signaling mechanisms involved in taste transduction, much less is known about how taste cells transmit this information to the nervous system. Recently we identified ATP as a key transmitter linking taste cells to activation of gustatory afferent fibers. Using mice that lack the purinergic receptors P2X2 and P2X3, we showed that these mice lack gustatory responses to all taste stimuli. Further experiments by our labs and others have shown that the taste cells that express bitter, sweet, and umami taste receptors release ATP via non-vesicular mechanisms, likely hemichannels composed of Pannexin1. Further, the ATP that is released is broken down to ADP by the ecto- nucleotidase NTPDase2, expressed on the membranes of the glial-like support cells in the taste bud. However, several questions remain about the role of ATP as a transmitter in taste buds. First, is Pannexin1 required for ATP release and full activation of gustatory afferents? This has not been tested in vivo. Further, why are sour and salty responses absent in the P2X2/3 double knockout mice when the only taste cells known to release ATP are the cells that respond to bitter, sweet, and umami stimuli? Finally, what is the role of the ecto-ATPase in the perdurance of the ATP released from taste buds and how does this impact gustatory function? In this new grant proposal we will use existing knockout mice to genetically eliminate key elements of purinergic signaling in taste buds. We will use an integrated systems neuroscience approach-- from cellular assays of ATP release to gustatory nerve recording and behavior-- to answer the following questions: (1) Is Pannexin1 required for ATP release and activation of gustatory nerve fibers? We will use both a global and a conditional knockout of Pannexin1 to address whether this channel mediates ATP release in taste cells, and whether it is necessary and sufficient for full activation of gustatory afferent fibers and taste guided behavior. (2) What is the role of NTPDase2 in the perdurance of ATP release? We will utilize NTPDase2 knockout mice to determine how NTPDase2 affects the magnitude and perdurance of the ATP that is released and what role this plays in the sensitivity of the afferent nerve fibers to taste stimuli. Results from these experiments will provide important new data about the role of ATP in gustatory function. By understanding how taste cells communicate with afferent nerve fibers, it may be possible to develop pharmaceutical agents that will interfere with this process and modulate taste function. This could have an important impact on health problems that result from disorders of food intake.

描述（由申请人提供）：虽然在识别味觉转导所涉及的受体和下游信号传导机制方面已经取得了实质性进展，但对于味觉细胞如何将此信息传递到神经系统的了解却少之又少。最近，我们发现 ATP 是连接味觉细胞和味觉传入纤维激活的关键递质。使用缺乏嘌呤能受体 P2X2 和 P2X3 的小鼠，我们发现这些小鼠缺乏对所有味觉刺激的味觉反应。我们实验室和其他实验室的进一步实验表明，表达苦味、甜味和鲜味受体的味觉细胞通过非囊泡机制（可能是由 Pannexin1 组成的半通道）释放 ATP。此外，释放的 ATP 被味蕾神经胶质样支持细胞膜上表达的核酸外切酶 NTPDase2 分解为 ADP。然而，关于 ATP 作为味蕾递质的作用仍然存在一些问题。首先，Pannexin1 是 ATP 释放和味觉传入完全激活所必需的吗？这尚未在体内进行测试。此外，为什么 P2X2/3 双基因敲除小鼠中没有酸味和咸味反应，而已知唯一释放 ATP 的味觉细胞是对苦味、甜味和鲜味刺激做出反应的细胞？最后，外源 ATP 酶在味蕾释放 ATP 的持久性中起什么作用？这对味觉功能有何影响？在这项新的资助提案中，我们将使用现有的基因敲除小鼠从基因上消除味蕾中嘌呤能信号传导的关键元件。我们将使用综合系统神经科学方法——从 ATP 释放的细胞测定到味觉神经记录和行为——来回答以下问题：(1) ATP 释放和味觉神经纤维激活是否需要 Pannexin1？我们将使用 Pannexin1 的全局敲除和条件敲除来解决该通道是否介导味觉细胞中 ATP 释放，以及它对于完全激活味觉传入纤维和味觉引导行为是否是必要和充分的。 (2) NTPDase2 在 ATP 持续释放中起什么作用？我们将利用 NTPDase2 敲除小鼠来确定 NTPDase2 如何影响所释放的 ATP 的大小和持久性，以及它在传入神经纤维对味觉刺激的敏感性中发挥什么作用。这些实验的结果将提供有关 ATP 在味觉功能中的作用的重要新数据。通过了解味觉细胞如何与传入神经纤维进行通信，有可能开发出干扰该过程并调节味觉功能的药剂。这可能对食物摄入失调引起的健康问题产生重要影响。