SIGNALING IN TASTE CELLS

描述(由申请人提供)：最近的发现表明味蕾比以前的研究要复杂得多。成熟的味觉细胞表现出不同的特性，并可以相互交流。有人建议，味觉感受器的化学感觉检测之后，味蕾中的感觉信号在传输到大脑之前形成，就像在其他感觉系统中发生的那样。然而，味蕾内细胞异质性和细胞间信号的重要性仍有待解释。我们将针对味蕾中最普遍的细胞--I型胶质细胞提出以下问题：1.I型味觉细胞是否调节味蕾中的离子环境？空间缓冲K+是中枢星形胶质细胞执行的一项关键功能。我们的数据表明，ROMK和其他某些顶端通道可能在味蕾中形成了这样的K+清除途径。我们将使用舌片中味蕾的共聚焦钙成像、传入神经记录和行为分析来测试使用ROMK和其他K+外流调节剂的生理、药理和遗传操作对K+积累的影响。2.I型味觉细胞是否使用GABA作为神经递质来调节味觉信号？我们的实验数据表明，I型细胞是味蕾GABA能回路中的关键角色。我们将完成一种独特的转基因小鼠品系的生产，在该品系中，黄色荧光蛋白(YFP)仅在味蕾的I型细胞中表达。然后，我们将使用这些和我们的其他转基因小鼠来鉴定受体的细胞类型选择模式，并使用共聚焦钙成像来分析这些细胞类型中GABA介导的反应，特别是关于对味觉诱发反应的影响。3.I型细胞是否起源于局部上皮，其寿命有多长？味蕾中的细胞估计平均寿命为10-14天。早期的研究并没有确定味觉细胞的类型。我们将使用一种新的技术来测定出生细胞，以评估不同类型的味觉细胞是否具有不同的寿命和谱系。通过这一系列可测试的假设和专注于I型味蕾细胞的强大新技术，我们将开始解决更大的、几十年前的问题：为什么化学感觉味蕾细胞形成群落(即味蕾)？味蕾中处理的是什么信号，细胞之间正在进行的交流在味觉接受中起着什么作用？ 与公共健康相关：味蕾通过口腔中味蕾中不同类型细胞的协调作用来检测营养和潜在的有毒物质。我们将研究位于味蕾中但类似于胶质细胞的细胞如何影响味蕾的敏感性。因为负责调节的蛋白质位于一个可接近的位置，了解这些机制就有可能对厌恶和食欲的味觉进行药物操纵。

DESCRIPTION (provided by applicant): Recent findings indicate that taste buds are much more complex than previously held. Mature taste cells display diverse properties and may communicate among themselves. There are suggestions that chemo-sensory detection by taste receptors is followed by a shaping of the sensory signal within the taste bud prior to transmission to the brain, much as occurs in other sensory system. Yet, the significance of cellular heterogeneity and intercellular signals within the taste bud remain to be explained. We will ask the following questions focused on the most prevalent cells in taste buds, the glial-like Type I cells: 1. Do Type I taste cells regulate the ionic environment in taste buds? Spatially buffering K+ is a key function performed by astrocytes in the CNS. Our data suggest that ROMK and certain other apical channels may form such a K+ clearance pathway in taste buds. We will use confocal Ca imaging of taste buds in lingual slices, afferent nerve recordings and behavioral assays to test the effects of K+ accumulation using physiological, pharmacological, and genetic manipulations of ROMK and other regulators of K+ efflux. 2. Do Type I taste cells use GABA as a gliotransmitter to modulate taste signals? Our pilot data suggest that Type I cells are key players in GABAergic circuits in taste buds. We will complete production of a unique transgenic mouse strain in which yellow fluorescent protein (YFP) is expressed only in Type I cells of taste buds. We will then use these and our other transgenic mice to identify the cell-type selective pattern of receptors and confocal Ca2+ imaging to analyze GABA-mediated responses in these cells types, especially with respect to the impact on taste-evoked responses. 3. Do Type I cells arise from local epithelium and what is their lifespan? Cells in taste buds have an estimated average lifespan of 10-14 days. Earlier studies did not confidently resolve taste cell types. We will employ a new technology for birth-dating cells to assess if the different taste cell types have different lifespans and lineages. Through this series of testable hypotheses and powerful new technologies focused on Type I taste bud cells, we will begin to address the larger, and decades-old question: why do chemosensory taste cells form communities (i.e. taste buds)? What signals are processed within taste buds and what role in taste reception does ongoing communication among the cells serve? PUBLIC HEALTH RELEVANCE: Taste buds detect nutritive and potentially poisonous materials through the coordinated action of distinct types of cells housed in taste buds throughout the oral cavity. We will investigate how cells located in taste buds, but resembling glia, may influence the sensitivity of taste buds. Because the proteins responsible for regulation are in an accessible location, understanding these mechanisms introduces the possibility of pharmacological manipulation of aversive and appetitive taste sensations.