Purinergic signaling in taste buds

味蕾中的嘌呤信号

• 批准号: 8865596
• 负责人: Sue C. Kinnamon
• 金额: $ 32.71万
• 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 2016-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8865596
• 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; taste stimuli; taste transduction; 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）：虽然在鉴定味觉转导中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，但对味觉细胞如何将该信息传递到神经系统知之甚少。最近，我们确定ATP作为连接味觉细胞激活味觉传入纤维的关键递质。使用缺乏嘌呤能受体P2 X2和P2 X3的小鼠，我们发现这些小鼠对所有味觉刺激都缺乏味觉反应。我们实验室和其他人的进一步实验表明，表达苦味，甜味和鲜味受体的味觉细胞通过非囊泡机制释放ATP，可能是由Pannexin 1组成的半通道。此外，释放的ATP被外核苷酸酶NTPD酶2分解为ADP，外核苷酸酶NTPD酶2在味蕾中的神经胶质样支持细胞的膜上表达。然而，关于ATP在味蕾中作为传递器的作用仍然存在一些问题。首先，Pannexin 1是ATP释放和味觉传入的完全激活所必需的吗？这尚未在体内进行测试。此外，为什么在P2 X2/3双敲除小鼠中没有酸和咸的反应，而已知释放ATP的味觉细胞是对苦、甜和鲜味刺激有反应的细胞？最后，外ATP酶在味蕾释放ATP的持久性中起什么作用，这又是如何影响味觉功能的？在这项新的拨款申请中，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的关键元素。我们将使用一个集成的系统神经科学的方法-从ATP释放的细胞测定味觉神经记录和行为-回答以下问题：（1）Pannexin 1是否需要ATP释放和激活味觉神经纤维？我们将使用全局和条件性敲除Pannexin 1来解决这个通道是否介导味觉细胞中的ATP释放，以及它是否是味觉传入纤维和味觉引导行为的完全激活所必需和足够的。(2)NTPDase 2在维持ATP释放中的作用是什么？我们将利用NTPDase 2敲除小鼠来确定NTPDase 2如何影响释放的ATP的大小和持久性，以及这在传入神经纤维对味觉刺激的敏感性中起什么作用。这些实验的结果将为ATP在味觉功能中的作用提供重要的新数据。通过了解味觉细胞如何与传入神经纤维进行交流，有可能开发出干扰这一过程并调节味觉功能的药物。这可能对食物摄入紊乱引起的健康问题产生重要影响。