Investigating the Molecular Basis of Mechanotransduction Channel Gating

描述（由候选人提供）：在细胞和分子水平上，人们对人类如何感知触觉知之甚少。即使是轻微的微风也会对皮肤产生足够的压力，从而启动一个快速的信号级联，立即将这种感觉传递给大脑。这种将机械刺激转化为神经元信号的过程被称为机械感觉，它对触觉、听觉、平衡、肾脏调节等感觉至关重要。机械感觉的组成部分是嵌入在细胞表面的蛋白质，称为离子通道，在张力或拉伸时打开。在哺乳动物中，上皮钠通道（ENaCs）和酸感离子通道（asic）与机械感觉有关，但对它们在这一过程中的作用知之甚少。秀丽隐杆线虫是一种常用于机械感觉研究的模式生物。本研究重点关注的两种秀丽隐杆线虫蛋白MEC-4和MEC-10，它们构成了感知轻柔触摸的通道，与ENaCs和asic属于同一个超家族。因此，研究MEC-4和MEC-10在其原生环境中获得的信息将与哺乳动物的触觉有关。在这个超级家族中，许多排列在通道孔中的残基是高度保守的，它们长期以来一直与通道功能有关。在本研究中，MEC-4和MEC-10形成的通道孔中发现的高度保守残基将发生突变，以便利用裂缝-蠕虫全细胞膜片钳技术确定特异性变化如何改变体内通道功能。确定这些残基的作用将增强在分子蛋白水平上对通道门控的理解。首先，将研究具有已知表型的突变。然后，将研究许多孔衬甘氨酸，以探讨GxxxG螺旋填料基序在通道门控途径中的重要性。这项工作将是第一次对这一重要区域进行彻底的体内电生理研究。机械敏感蛋白通道参与许多重要的过程，如解释触觉和听觉，调节肾功能，控制血压，平衡细胞间盐和水的比例。了解这些通道的功能可以为干预打开大门，防止或减缓它们控制的重要人类功能的衰退。

DESCRIPTION (provided by candidate): On the cellular and molecular level, exactly how humans sense touch is poorly understood. Even a slight breeze exerts enough pressure against the skin to start a rapid signaling cascade that immediately transmits the sensation to the brain. This process of translating mechanical stimuli into neuronal signals is called mechanosensation, and it is critical for the sense of touch, hearing, balance, kidney regulation, and more. Integral components of mechanosensation are proteins embedded within the surface of a cell called ion channels that open upon tension or stretch. In mammals epithelial sodium channels (ENaCs) and acid- sensing ion channels (ASICs) are linked to mechanosensation, but little is known about how they function in this process. C. elegans is a model organism often used for studying mechanosensation. The two C. elegans proteins that are the focus of this proposal, MEC-4 and MEC-10, constitute the channel that senses gentle touch and are in the same super family as ENaCs and ASICs. Thus, information gained from studying MEC-4 and MEC-10 in their native environment will be relevant to mammalian touch sensation. Many of the residues that line the pore of the channels in this super family are highly conserved, and they have long been implicated in channel function. In this proposal highly conserved residues found in the pore of the channel formed by MEC-4 and MEC-10 will be mutated in order to determine how specific changes alter channel function in vivo using the slit-worm whole-cell patch clamp technique. Determining the roles of these residues will enhance the understanding of channel gating at the molecular protein level. First, mutations with known phenotypes will be studied. Then, the many pore-lining glycines will be investigated to probe the importance of the GxxxG helix-packing motif in the gating pathway of the channel. This work will be the first thorough in vivo electrophysiological investigation of this important region. Mechanosensitive protein channels are involved in many vital processes such as interpreting the sensations of touch and hearing, regulating kidney function, controling blood pressure, and balancing the ratio of salt and water across cells. Understanding how these channels function could open the door to interventions that prevent or slow the decline of the important human functions that they control.