VOLTAGE-DEPENDENT ION CHANNELS IN GUSTATION

描述（申请者提供）：味觉感知是由味蕾细胞表面的有味分子与蛋白质相互作用而产生的。这些味觉信号随后在味蕾中被转导、处理、编码并由脑神经传递到大脑。我们的长期研究目标是对参与味觉信号转导、味蕾编码和中枢神经系统解码的关键蛋白进行分子识别和功能表征，最终重建味觉感觉和感知的分子事件。我们利用分子克隆和功能分析鉴定和表征了许多味觉转导成分，包括G蛋白偶联味觉受体T1R3、G蛋白亚基和瞬时受体电位离子通道TRPM5。为了了解TRPM5下游的分子事件，并揭示负责酸味和咸味的离子通道，我们确定了味蕾细胞中6个电压依赖性钙通道的表达。本研究的具体目的是：1)在味蕾细胞中识别电压依赖性钙通道亚基并将其与已知的味觉信号分子共定位；2)从味蕾中分离的这些电压依赖性钙通道的异源表达和功能表征；3)通过监测这些电压依赖性钙通道在味觉刺激下对味蕾细胞内钙浓度升高和突触活性的药理和遗传干扰，确定这些通道在味蕾突触传递中的可能作用；4)最后，通过味觉神经记录和突变动物行为实验，确定这些电压依赖性钙通道在味觉感觉中的可能作用。这些研究结果将对酸、盐、苦、甜和鲜味味觉转导、突触传递和末梢编码在味觉器官中的分子机制提供新的见解。从这一努力中获得的知识将进一步加深我们对味觉障碍的分子基础的理解，如味觉障碍、味觉障碍、味觉减退和老年障碍，并可能导致有效的治疗。

DESCRIPTION (provided by applicant): Taste perception is initiated by the interaction of sapid molecules with proteins on the surface of taste bud cells. These gustatory signals are subsequently transduced, processed in taste buds, coded and transmitted by cranial nerves to the brain. The long-term objective of our research program is to molecularly identify and functionally characterize key proteins that are involved in taste signal transduction and coding in taste buds, and decoding in the central nervous system, and eventually to reconstruct the molecular events of taste sensation and perception. We have used molecular cloning and functional analyses to identify and characterize a number of taste transduction components, including a G-protein coupled taste receptor T1R3, G protein subunits and a transient receptor potential ion channel TRPM5. In order to understand the molecular events downstream of TRPM5 and to reveal ion channels that are responsible for sour and salty tastes, we have determined the expression of six voltage-dependent calcium channels in taste bud cells. The specific aims of this proposal are: 1) to identify and colocalize voltage-dependent calcium channel subunits with known taste signaling molecules in taste bud cells; 2) to heterologously express and functionally characterize novel isoforms of these voltage-dependent calcium channels isolated from taste buds; 3) to determine possible roles of these voltage-dependent calcium channels in taste bud synaptic transmission by monitoring the effect of pharmacological and genetic perturbation of these channels on the elevation of intracellular calcium concentrations and synaptic activity in taste bud cells in response to taste stimuli; 4) finally, to determine possible roles of these voltage-dependent calcium channels in taste sensation by gustatory nerve recording and animal behavioral tests with mutant animals. The results of these studies will yield new insights into the molecular mechanisms underling sour, salt, bitter, sweet and umami taste transduction, synaptic transmission and peripheral coding in the end organs of taste. The knowledge gained from this endeavor will further our understanding of the molecular bases of taste disorders such as malgeusia, dysgeusia, hypogeusia and ageusia and may lead to effective treatment.