Molecular mechanisms of vestibular hair cell exocytosis

前庭毛细胞胞吐作用的分子机制

• 批准号: 7091346
• 负责人: FELIX E SCHWEIZER
• 金额: $ 22.63万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2010-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7091346
• 关键词: afferent nerve; cell membrane; ear hair cell; electrophysiology; exocytosis; glutamate receptor; laboratory mouse; laboratory rat; membrane fusion; molecular biology; neural transmission; neurotransmitter transport; protein protein interaction; protein structure function; sensory feedback; synapses; tissue /cell culture; vestibular apparatus; voltage /patch clamp

DESCRIPTION (provided by applicant): Mechanosensory hair cells in the vestibular system transduce information about head position and movement into neuronal signals. The aim of this application is to elucidate the molecular mechanisms underlying synaptic transmission from vestibular hair cells to afferent fibers. The hair cells afferent synapse exhibits anatomical (synaptic bodies or ribbons) and functional (responding to graded depolarizations) specializations that distinguish them from other synapses in the nervous system. We here propose to investigate which proteins and protein-interactions important at conventional synapses are important for hair cell synaptic transmission. Furthermore, vestibular physiology lacks an understanding of the functional difference between type I and type II hair cells. Type I hair cells, found only in amniotes, are engulfed by the afferent nerve, suggesting differences in synaptic physiology. The proposed experiments are therefore further aimed at understanding the molecular and functional difference in neurotransmitter release between vestibular type I and type II hair cells. These experiments will further our molecular and biophysical understanding of the first synapse in the vestibular and auditory system. Hair cells release neurotransmitter from the basolateral end of the cell body, offering relatively easy access to synaptic areas for the introduction of toxins and peptides to acutely perturb protein function. Exocytosis will be monitored directly by measuring the increase in cell membrane area that occurs when vesicles fuse with the plasma membrane. Specific Aim 1 tests the hypothesis that exocytosis is regulated by a specific subset of SNARE proteins. Specific Aim 2 addresses whether vesicle recycling is limiting for exocytosis. In Specific Aim 3 the hypothesis is tested that glutamate acts in a positive feedback loop to enhance release especially in type I hair cells. A detailed understanding of the proteins and mechanisms of release at this initial sensory synapse aid in identifying novel therapeutic approaches targeting vestibular dysfunction.

描述（由申请人提供）：前庭系统中的机械感觉毛细胞会导致有关头部位置和移动到神经元信号的信息。该应用的目的是阐明从前庭毛细胞到传入纤维的突触传播的分子机制。毛细胞传入突触表现出解剖（突触物体或丝带）和功能性（对分级去极化）的特殊性，可以将它们与神经系统中的其他突触区分开。我们在这里建议研究哪些蛋白质和蛋白质相互作用在常规突触中很重要，对于毛细胞突触传播很重要。此外，前庭生理学缺乏对I型和II型毛细胞之间功能差异的了解。仅在羊膜中发现的I型毛细胞被传入神经所吞没，表明突触生理的差异。因此，提出的实验进一步旨在了解前庭I型和II型毛细胞之间神经递质释放的分子和功能差异。这些实验将进一步进一步，我们对前庭和听觉系统中第一个突触的分子和生物物理理解。 毛细胞从细胞体的基底外侧释放神经递质，提供相对容易进入突触区域，以引入毒素和肽来急性扰动蛋白质功能。通过测量囊泡与质膜融合时发生的细胞膜区域的增加，可以直接监测胞吐作用。特定的目标1检验了胞吐作用受特定子集的SNARE蛋白质调节的假设。具体目标2解决了囊泡回收是否限制了胞吞作用。在特定目标3中，检验了假设，即谷氨酸在正反馈循环中起作用，以增强释放，尤其是在I型毛细胞中。在此最初的感觉突触中，对释放的蛋白质和机制的详细理解有助于识别针对前庭功能障碍的新型治疗方法。