CAA: Molecular Basis for the Cholinergic Modulation of Auditory Hair Cell Properties

在哺乳动物内耳中，感觉细胞的亚群接收来自大脑的抑制性输入。 像这样从大脑到感觉器官的神经元反馈通路被称为传出通路或下行通路。 类似的神经反馈也调节鱼类的侧线和爬行动物、两栖动物和鸟类的内耳的感觉知觉。 事实上，这种传出抑制已被保存在动物类表明这一过程的根本重要性。 这种听觉传出通路通过调节感觉细胞的兴奋性，有助于我们听觉的灵敏度和频率选择性。 然而，这种调节反馈的机制在分子水平上还不清楚。 已知乙酰胆碱受体α 9和α 10以及小电导Ca 2+激活的钾通道SK 2（其通常与钙源共定位）是哺乳动物听觉感觉细胞中所需的分子组分。 本计画应用分子生物学策略来鉴定参与这些离子通道选择性定位、聚集及功能关联的蛋白质。 此外，已经构建了SK 2和α 9/α 10受体的荧光标记嵌合体，以应用最先进的光学技术来研究其功能相互作用的生化基础。 这些发现将促进我们对感觉感知的生化原理的理解，包括所涉及的离子通道之间的蛋白质-蛋白质相互作用。 在完成该项目的同时，研究生和博士后研究员将接受培训，以利用强大的电生理和光学研究技术以及生物化学和分子技术。 这些都是神经科学和其他生物学研究前沿的基本技术，对可兴奋细胞中含有离子通道的大分子复合物的详细了解是基础。

In the mammalian inner ear a subpopulation of the sensory cells receive inhibitory inputs from the brain. Neuronal feedback pathways such as this one, from the brain to the sensory organ are called efferent or descending pathways. Similar neural feedback modulates sensory perception also in the lateral lines of fish and in the inner ears of reptiles, amphibians, and birds. The fact that this efferent inhibition has been conserved across animal classes suggests the fundamental importance of this process. This auditory efferent pathway contributes to the exquisite sensitivity and frequency selectivity of our sense of hearing by modulating the excitability of the sensory cells. However, the mechanisms underlying this modulatory feedback are not understood at the molecular level. It is known that the acetylcholine receptors alpha 9 and alpha 10 and the small conductance Ca2+-activated potassium channels SK2, which are often co-localized with calcium sources are required molecular components in the mammalian auditory sensory cells. This project applies a molecular biology strategy to identify proteins involved in the selective localization, clustering, and functional associations between these ion channels. Additionally, fluorescently tagged chimeras of the SK2 and of the alpha 9/ alpha 10 receptors have been constructed to apply state-of-the-art optical techniques to the investigation of the biochemical basis of their functional interactions. The findings will advance our understanding of the biochemical principles underlying sensory perception including protein-protein interactions between the ion channels involved. While completing this project graduate students and post-doctoral fellows will be trained to utilize powerful electrophysiological and optical research techniques as well as biochemical and molecular techniques. These are essential techniques in neuroscience and other biological research frontiers for which a detailed understanding of macromolecular complexes harboring ion channels in excitable cells is fundamental.