MOLECULAR MECHANISMS OF TRANSDUCTION AND TRANSMITTER RELEASE IN TASTE CELLS

当化学刺激物与细胞相互作用时，味觉传导开始。 味觉感受器细胞的顶膜。这种相互作用最终导致 细胞内钙离子的增加和递质的释放 将味觉细胞连接到味觉神经纤维上在下一个供资期间 将检查转导和递质释放的方面。的 前两个具体目标集中在甜味转导，而第三个目标 检测味觉细胞释放的递质 目的1：研究味觉蛋白在甜味信号转导中的作用。 在上一个资助期，有证据表明，糖激活 cAMP途径，而合成甜味剂激活的途径涉及 IP/3和DAG。这两个第二信使途径显然汇聚在 a K+传导性，使味觉细胞去极化。在下一个供资期 提出实验来检查化学感觉特异性的作用， G蛋白，味蛋白，在这个过程中。一个转基因小鼠品系将 从R. Margolskee博士获得，其中味蛋白启动子已经被 与绿色荧光蛋白（GFP）基因相连。因此，味觉细胞 表达味觉调节素的细胞将是荧光的， 生理记录Ca 2+成像、全细胞记录和人 心理物理学研究将被用来确定gustducin在 甜蜜的传导 目的2：鉴定介导Sweet最终步骤的K+通道 转导 单通道记录将用于表征K+通道， 对甜味刺激的反应是关闭的具体来说，实验是 建议确定糖是否靶向相同的通道， 合成甜味剂，以及磷酸化是否需要通道 结束 目的3：研究IP/3在味觉神经递质释放中的作用 细胞 最近的结果表明，在泥小狗味觉细胞变性转导 IP/3介导的钙从细胞内储存的释放可能 足以触发味觉细胞释放递质未来 资助期突触囊泡释放的味觉细胞将成像 直接使用荧光膜染料FM 1 -43。实验 提出确定IP/3和Ca/2+在此过程中的作用。 这些研究将提供关于 味觉传导中的味蛋白及其作用机制 从味觉细胞中释放出递质。

Taste transduction is initiated when chemical stimuli interact with the apical membrane of taste receptor cells. The interaction ultimately leads to an increase in intracellular calcium and release of transmitter from the taste cell onto gustatory nerve fibers. During the next funding period aspects of both transduction and transmitter release will be examined. The first two specific aims focus on sweet transduction, while the third aim examines transmitter release from taste cells. Aim 1: To determine the role of gustducin in sweet transduction. In the previous funding period evidence was provided that sugars activate the cAMP pathway, while synthetic sweeteners activate a pathway involving IP/3 and DAG. These two second messenger pathways apparently converge on a K+ conductance to depolarize taste cells. In the next funding period experiments are proposed to examine the role of the chemosensory-specific G protein, gustducin, in this process. A transgenic line of mice will be obtained from Dr. R Margolskee in which the gustducin promoter has been linked to the gene for Green Fluorescent Protein (GFP). Thus, taste cells that express gustducin will be fluorescent and can be targeted for physiological recording. Ca2+ imaging, whole cell recording, and human psychophysical studies will be used to determine the role of gustducin in sweet transduction. Aim 2: To identify the K+ channels that mediate the final step in sweet transduction. Single channel recording will be used to characterize the K+ channels that are closed in response to sweet stimuli. Specifically, experiments are proposed to determine whether the same channels are targeted by sugars and synthetic sweeteners, and whether phosphorylation is required for channel closure. Aim 3: To examine the role of IP/3 in neurotransmitter release from taste cells. Recent results on denatonium transduction in mudpuppy taste cells suggests that IP/3-mediate release of calcium from intracellular stores may be sufficient to trigger transmitter release from taste cells. In the next funding period synaptic vesicle release from taste cells will be imaged directly using the fluorescent membrane dye FM1-43. Experiments are proposed to determine the role of IP/3 and Ca/2+ in this process. These studies will provide important new information about the role of gustducin in sweet taste transduction and mechanisms involved in the release of transmitters from taste cells.