Mechanisms of mechanosensory transduction in Merkel cells

描述（由申请人提供）：本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转导分子。这些感觉对于社会互动和避免有害环境是必不可少的;然而，在病理生理状态下，触摸超敏反应会导致异常性疼痛和慢性疼痛。 本申请的目的是确定默克尔细胞-神经突复合体中的感觉转导机制。这些复合物是皮肤中非常敏感的触觉感受器，可以编码形状和纹理，例如人类的盲文图案。它们由表皮默克尔细胞和躯体感觉传入神经元末梢组成。本申请集中于小鼠默克尔细胞-神经突复合体生理学，因为它是最适合于体外和体内实验的哺乳动物触觉受体。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然未知。 这项研究的中心假设是表皮默克尔细胞是机械敏感细胞，通过离子通道抵抗力。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。这一假设将直接测试相结合的生理技术（钙成像方法和电生理学），以分析力激活的信号在默克尔细胞和分子方法，以确定编码mechanotransduction机制的基因。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。具体目标是：1.确定力激活离子通道是否介导默克尔细胞中的机械转导。 2.评价细胞外系链对默克尔细胞中触摸敏感性的贡献。 3.鉴定默克尔细胞中机械转导所需的离子通道亚基。 公共卫生相关性：该应用程序旨在确定皮肤中触觉和疼痛受体中机械传导所必需的基因。当机械感觉被周围神经损伤破坏时，伴随着大量的疾病（糖尿病），感染（HIV）和医疗干预（化疗），损伤往往导致永久性损伤，可能需要截肢。此外，触摸超敏反应是慢性疼痛的常见特征，慢性疼痛是困扰> 5000万美国人的毁灭性公共卫生问题。通过鉴定启动神经元信号的分子，这些分子1）在周围神经病变中受损，2）在慢性疼痛中过度活跃，这些研究可以为开发这些病理生理学状况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.