MECHANOTRANSDUCTION IN BARORECEPTOR NEURONS AND DROSOPHILA SENSORY NEURONS

动脉压力感受器是仅限于颈动脉的感觉末梢。 窦和主动脉弓，但具有强大的调节作用。他们 将动脉血压信号转化为神经体液调节 心血管结构和动态平衡。尽管有大量的 有关压力感受器(BR)神经激活决定因素的信息， 机电学的分子、细胞和功能决定因素 它们感觉神经末梢的转导在很大程度上是未知的。项目 这本PPG的IV讲的是机械感觉的神经生物学。这 四年前启动的项目(IV.A.1)，重点是1) 结状神经节内BR神经元的鉴定2)结节神经节的培养 体外；3)建立其机械性能的定量系统 激活；以及4)它们的响应的定义以及测量 全细胞膜电流，单通道[Ca~(2+)]i 通过测量寻找细胞机制的功能关联 在活体内颈动脉窦神经活动。基于非常激动人心的 在初步研究中，我们现在建议检验以下假设 ENAC/退行性蛋白家族代表离子通道负责 BR神经元的力电转导。这一假设获得了一个 触觉之间的基因联系的发现提供了强有力的理由 线虫的感觉和机械激活的证据 ENAC/退行性通道。在初步研究中，我们发现1) ENAC/Degenerin、Gamma ENaC、beta ENaC和BNc1亚单位(最近 从脑中克隆)，在小鼠的主动脉弓外膜中表达 BR神经末梢和BR神经元所在的结状神经节， 2)转染卵母细胞的BNC1a的活性为 被已知的机械感觉通道阻滞剂Gd3阻断；以及3) 机械刺激时BR神经元内[Ca~(2+)]i的升高可被 阿米洛利，一种已知的ENaC/退行性蛋白通道阻滞剂。我们的目标是： 第一，识别ENaC/Degenerin ENaC/Degenerin通道；第三，识别ENaC/Degenerin ENaC/Degenerin通道 试图扰乱BR对机械刺激的反应 细胞、器官和整个动物水平上的显性- ENaC/退化素家族阴性。 该项目的独特之处在于两家领先的 拥有自主神经控制神经生物学专业知识的实验室(阿布) 以及离子通道的分子生物学(威尔士)。添加了 在成像、转基因动物和基因方面的优秀核心支持 转移，成功解决这个问题的希望是 已经确定了。

The arterial baroreceptors are sensory endings restricted to the carotid sinus and aortic arch but with powerful regulatory influences. They transduce arterial pressure signals into neurohumoral regulation of cardiovascular structure and homeostasis. Despite a large amount of information on the determinants of activation of baroreceptor (BR) nerves, the molecular, cellular and functional determinants of mechanoelectrical transduction at their sensory nerve endings are largely unknown. Project IV of this PPG addresses the neurobiology of mechanosensation. This Project (IV.A.1) which was initiated four years ago, as focused on 1) the identification of BR neurons in the nodose ganglion; 2) culturing them in vitro; 3) the development of a quantitative system for their mechanical activation; and 4) the definition of their responses with measurements of whole cell membrane currents, single-channel openings [Ca2+]i. A functional correlate of the cellular mechanisms was sought by measurements of carotid sinus nerve activity in vivo. Based on very exciting preliminary studies, we now propose to test the hypothesis that the ENaC/degenerin family of proteins represent ionic channel responsible for mechanoelectrical transduction in BR neurons. This hypothesis gains a strong rationale from the discovery of a genetic link between touch sensation in C. Elegans and the evidence of mechanical activation of ENaC/degenerin channels. In preliminary studies we found that 1) the subunits of ENAC/degenerin, gamma ENaC; beta ENaC and BNC1 (recently cloned from brain), are expressed in the aortic arch adventitia in the nodose ganglia where the BR nerve terminals and BR neurons are located, respectively; 2) the activity of BNC1a (transfected into oocytes) is blocked by Gd3+, a known blocker of mechanosensory channels; and 3) the rise in [Ca2+]i in BR neurons during mechanical stimulation is blocked by amiloride, a known blocker of the ENaC/degenerin channels. Our aims are: first, to identify ENaC/degenerin ENaC/degenerin channels; and third, to attempt to disrupt the BR responses to mechanical stimulation at the cellular, organ and whole animal level by transfection of dominant- negatives of ENaC/degenerin family. The uniqueness of the project is in the joining of two leading laboratories, with expertise in neurobiology of autonomic control (Abboud) and in the molecular biology of ion channels (Welsh). With the added support of excellent cores in imaging, transgenic animals, and gene transfer, the promise of successful pursuit of this problem is ascertained.