Molecular Basis of Sensory Transduction in C. elegans

描述（由申请人提供）：最轻柔的微风、最粗糙的砂纸和最锋利的针都能被我们的体感系统检测到，该系统由嵌入皮肤中的数千个触觉敏感的机械感受器神经元组成。人们普遍认为，物理力是通过激活专门的离子通道（称为“机电转导”或MeT通道）转化为神经信号的，但对这一过程的分子和物理基础的理解仍处于初级阶段。所有动物都有触觉能力，最近的研究表明，线虫和哺乳动物的体感神经元具有相似的反应动力学（Geffeney和Goodman， Neuron 74:609, 2012）。在依赖DEG/ENaC或TRP通道蛋白形成MeT通道的神经元中可以看到这种功能守恒，这一发现意味着反应特性主要是由细胞环境赋予的，而不是离子通道蛋白固有的。该研究计划的长期目标是了解细胞膜和细胞骨架如何调节物理力传递到触摸受体神经元（trn）中表达的MeT通道，并发现与触摸诱发的MeT通道门控相关的结构重排。一般的方法是将鉴定出的trn中MeT通道门控的体内记录与秀丽隐杆线虫的遗传扰动结合起来，遗传扰动会改变多不饱和脂肪酸的生物合成和细胞膜功能，2)破坏微管和细胞骨架，3)破坏MEC-4蛋白中对钠选择性天然MeT通道形成至关重要的选定结构域。这项工作将与光遗传学研究相结合，旨在确定影响MeT通道的因素，但不包括下游信号事件，并与异源细胞中表达的MeT通道的生物物理分析相结合。拟议的研究结合了感觉生物物理学的专业知识，从已鉴定的秀丽隐杆线虫神经元的体内电记录，遗传分析，以获得对触觉的深刻理解。从这些研究中学到的东西有可能提高对触觉及其在疾病、化疗期间和正常衰老过程中的功能障碍的理解。

DESCRIPTION (provided by applicant): The gentlest breeze, the roughest sandpaper, and the sharpest pin are detected by our somatosensory system, which is composed of thousands of touch-sensitive mechanoreceptor neurons embedded in the skin. It is widely understood that physical force is transduced into neural signals through activation of specialized ion channels (called 'mechano-electrical transduction' or MeT channels), but understanding of the molecular and physical basis of this process remains rudimentary. All animals have the ability to sense touch and recent work has shown that nematode and mammalian somatosensory neurons have similar response dynamics (reviewed in Geffeney and Goodman, Neuron 74:609, 2012). This functional conservation is seen in neurons that rely on either DEG/ENaC or TRP channel proteins to form MeT channels, a finding which implies that response properties are conferred primarily by the cellular environment and not intrinsic to the ion channel proteins. The long-term goal of the proposed research program is to understand how the cell membrane and cytoskeleton regulate the delivery of physical force to MeT channels expressed in touch receptor neurons (TRNs) and discover the structural rearrangements associated with touch-evoked MeT channel gating. The general approach will be to combine in vivo recording of MeT channel gating in identified TRNs with genetic perturbations in C. elegans nematodes that 1) alter biosynthesis of polyunsaturated fatty acids and cell membrane function, 2) disrupt the microtubule and spectrin cytoskeleton and 3) disrupt selected domains in the MEC-4 proteins crucial to the formation of the sodium-selective native MeT channels,. This work will be paired with optogenetics studies designed to identify factors that affect MeT channels, but not downstream signaling events and with biophysical analysis of MeT channels expressed in heterologous cells. The proposed research combines expertise in sensory biophysics, in vivo electrical recording from identified C. elegans neurons, genetic analysis, to derive a profound understanding of the sense of touch. What is learned from these studies has the potential to improve understanding of touch sensation and its dysfunction in disease, during chemotherapy and as a consequence of normal aging.