Mechanisms of mechanosensory transduction in Merkel cells

描述(申请人提供)：这项研究的长期目标是发现在哺乳动物中启动触摸和疼痛的力传导分子。这些感觉对于社会交往和避免有害环境是必不可少的；然而，在病理生理状态下，触摸过敏会导致超敏和慢性疼痛。本应用的目的是确定Merkel细胞-轴突复合体中的感觉转导机制。这些复合体是皮肤上极其敏感的触摸感受器，可以编码形状和纹理，比如人类的盲文图案。它们由表皮Merkel细胞和体感传入神经元的终末组成。这一应用侧重于小鼠Merkel细胞-轴突的复杂生理学，因为它是哺乳动物最容易接受体外和体内实验的触摸感受器。虽然它们是脊椎动物表皮中仅有的四种保守细胞类型之一，但默克尔细胞在皮肤生物学中的作用仍不清楚。这项拟议研究的中心假设是，表皮默克尔细胞是通过离子通道传递力的机械敏感细胞。如果是真的，产生的电信号将通过感觉神经元发送到大脑，以编码温柔的触摸。这一假设将通过结合生理学技术(钙成像方法和电生理学)来分析默克尔细胞中的力激活信号，以及通过分子方法来识别编码机械转导机制的基因来直接检验。简化的体外系统将用于阐明机械转导分子，完整的成像将评估体内默克尔细胞的触摸敏感性。其具体目的是：1.确定力激活离子通道是否介导了Merkel细胞的机械转导。2.评价细胞外系绳对Merkel细胞触觉敏感性的影响。3.确定Merkel细胞机械转导所需的离子通道亚基。与公共健康相关：该应用程序旨在识别触摸机械转导和皮肤疼痛感受器所必需的基因。当机械感觉被周围神经损伤扰乱时，周围神经损伤伴随着大量疾病(糖尿病)、感染(艾滋病毒)和医疗干预(化疗)，损伤往往会导致永久性损伤，可能需要截肢。此外，触觉过敏是慢性疼痛的一个常见特征，这是一个折磨着5000万美国人的毁灭性公共卫生问题。通过识别启动神经信号的分子，这些分子1)在周围神经病中受损，2)在慢性疼痛中过度活跃，这些研究可能为开发针对这些病理生理条件的新疗法提供分子靶点。

DESCRIPTION (provided by applicant): The long-term goal of this research is to discover the force-transduction molecules that initiate touch and pain in mammals. These senses are essential for social interactions and for avoiding harmful environments; however, in pathophysiological states, touch hypersensitivity contributes to allodynia and chronic pain. The objective of this application is to define sensory transduction mechanisms in Merkel cell-neurite complexes. These complexes are exquisitely sensitive touch receptors in the skin that encode shapes and textures, such as Braille-like patterns in humans. They are made up of epidermal Merkel cells and the terminals of somatosensory afferent neurons. This application focuses on mouse Merkel cell-neurite complex physiology because it is the mammalian touch receptor that is most amenable to in vitro and in vivo experiments. Although they are one of only four conserved cell types in the vertebrate epidermis, the role of Merkel cells in skin biology is still unknown. The central hypothesis of the proposed research is that epidermal Merkel cells are mechanosensitive cells that transduce force via ion channels. If true, the resulting electrical signals will be sent via sensory neurons to the brain to encode gentle touch. This hypothesis will be directly tested by combining physiological techniques (calcium imaging approaches and electrophysiology) to analyze force-activated signals in Merkel cells and molecular approaches to identify genes that encode mechanotransduction machinery. Simplified in vitro systems will be used to elucidate mechanotransduction molecules, and intact imaging will assess the touch-sensitivity of Merkel cells in vivo. The specific aims are to: 1. Determine whether force-activated ion channels mediate mechanotransduction in Merkel cells. 2. Evaluate the contribution of extracellular tethers to touch sensitivity in Merkel cells. 3. Identify ion-channel subunits required for mechanotransduction in Merkel cells. PUBLIC HEALTH RELEVANCE: The application aims to identify genes essential for mechanotransduction in touch and pain receptors in the skin. When mechanosensation is disrupted by peripheral nerve damage, which accompanies a vast number of diseases (diabetes), infections (HIV) and medical interventions (chemotherapy), injuries often lead to permanent impairment that can necessitate limb amputation. Moreover, touch hypersensitivity is a common feature of chronic pain, a devastating public health problem afflicting >50 million Americans. By identifying the molecules that initiate neuronal signals that are 1) impaired in peripheral neuropathy and 2) overly active in chronic pain, these studies may provide molecular targets for the development of new therapeutics for these pathophysiological conditions.