Calcium Buffering Mechanisms in Taste Cells

说明(申请人提供)：钙是许多细胞过程中重要的第二信使；因此，它的存在在细胞内受到严格的调控。细胞至少有五种钙缓冲机制：质膜上的钙-三磷酸腺苷酶和钠/钙交换器、内质网上的钙-三磷酸腺苷酶、线粒体和胞内钙缓冲蛋白。由于钙的升高是味觉转导的最后一步，因此在味觉细胞中钙的存在也必须受到严格的调控；然而，味觉细胞使用的钙缓冲机制尚不清楚。可能不同的钙缓冲机制有助于钙信号的形成和调节，以响应味觉刺激。这可能是决定味觉细胞如何与其他细胞交流的关键。本申请旨在描述味觉细胞中存在的钙缓冲机制。它将它们的表达与味蕾中存在的不同细胞类型相关联。以前已经表明，味觉细胞有两种截然不同的电生理特征，有电压门控钙通道的和没有电压门控钙通道的。这两个不同的轮廓与细胞类型有松散的关联。第一个假设是，根据细胞是否表达钙通道，会有不同的钙缓冲机制。第二个假设是，钙缓冲机制是细胞对味觉刺激反应形成的重要组成部分。这一应用的具体目的是：(1)表征存在于味觉细胞中的钙缓冲机制的表达，并将其表达与不同的细胞类型相关联；(2)确定味觉细胞中钙缓冲机制的生理作用，并确定它们在形成对味觉刺激的钙反应中的作用。这些目标将通过使用AIM 1的分子技术和AIM 2的钙成像技术来实现。拟议的实验结果将为味觉细胞如何产生钙信号并与其他细胞/传入神经元通信提供新的信息。这些数据将确定味觉细胞和使用PLC信号通路导致细胞内钙释放的细胞之间是否存在差异。味觉细胞通过电压门控钙通道进行钙内流。这些数据将进一步加深我们对味觉细胞如何产生信号以回应味觉刺激的理解。

DESCRIPTION (provided by applicant): Calcium is an important second messenger for many cellular processes; therefore, its presence is tightly regulated within cells. Cells have developed at least five calcium buffering mechanisms: the plasma membrane Ca2+-ATPase and Na+/Ca2+ exchanger, the Ca2+-ATPase on the endoplasmic reticulum, the mitochondria, and cytosolic calcium buffering proteins. Since a rise in calcium is the final step in taste transduction, the presence of calcium must be tightly regulated in taste cells as well; however, the calcium buffering mechanisms used by taste cells are not known. It is likely that different calcium buffering mechanisms contribute to the formation and modulation of the calcium signal in response to taste stimuli. This is probably critical in determining how a taste cell communicates to other cells. This application intends to characterize the calcium buffering mechanisms that are present in taste cells. It will correlate their expression with the different cell types that are present in taste buds. It has been shown previously that there are two distinct electrophysiological profiles in taste cells, those with voltage gated calcium channels and those without. These two different profiles correlate loosely with cell type. The first hypothesis is that there will be different calcium buffering mechanisms, depending on whether the cells express calcium channels or not. The second hypothesis is that calcium buffering mechanisms are important components in the formation of the cell's response to taste stimuli. The specific aims of this application are: (1) Characterize the expression of calcium buffering mechanisms present in taste cells and correlate their expression to different cell types; (2) Determine the physiological role of calcium buffering mechanisms in taste cells and determine their role in shaping the Ca2+ response to taste stimuli. These aims will be accomplished by using molecular techniques for aim 1 and calcium imaging for aim 2. Results from the proposed experiments will provide new information about how taste cells generate Ca2+ signals and communicate to other cells/afferent neurons. These data will determine if there are differences between taste cells that have calcium influx through voltage gated calcium channels and cells that use the PLC signaling pathway that results in calcium release from intracellular stores. This data will further our understanding about how taste cells generate a signal in response to a taste stimuli.