SNARE-dependence of the exocytosis at the inner hair cell ribbon synapse

内毛细胞带突触胞吐作用的 SNARE 依赖性

• 批准号: 122776753
• 负责人: Professor Dr. Tobias Moser
• 金额: --
• 依托单位: Unité INSERM U583
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2009
• 资助国家: 德国
• 起止时间: 2008-12-31 至 2010-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/122776753?language=en
• 关键词: SNARE; dependence; exocytosis; inner; hair

The sensory systems provide the organism with Information about the extemal world. Acoustic information, for example, is processed by the auditory system involving transduction of mechanical stimuli by hair cells of the cochlea. Finally acoustic information is encoded at the ribbon synapses of the inner hair cells (lHCs). Although molecular biological and biophysical works have initiated major progress in investigating ribbon synapse, its molecular physiology is still poorly understood. Work of this DFG-funded project has raised the provocative question whether this synapse employs the archetypical neuronal SNARE complex. During exocytosis in most synapses, a four-helical coiled-coil protein complex is formed between the three SNARE proteins syntaxin 1, synaptobrevin 2 and SNAP-25. It bridges vesicle and plasma membrane and has been implied from docking to fusion step of exocytosis. During the first funding period Regis Nouvian has made the striking observation that exocytosis in IHCs is resistant to clostridial neurotoxins E and D, which in many other neurosecretory preparations interfere with exocytosis by cleaving SNAP-25 and synaptobrevin, respectively. Moreover, a mouse mutant with a loss of function mutafion in the synaptobrevin 1 gene showed normal IHC exocytosis, which was unexpected, given that synaptobrevin 1 had been formely identified in guinea pig IHCs. When exploring the expression of SNAREs in mouse IHCs we did not find consistent evidence for the expression of neuronal SNAREs. The objective of this grant renewal is to identify the SNAREs involved in IHC exocytosis by further experiments on the expression of SNAREs (single-cell PCR, immunohistochemistry and analysis of knock-in mice for fluorescently tagged variants of SNAREs) and by further testing the effects of clostridial neurotoxins. This work will be performed in Göttingen in collaboration with Regis Nouvian, who initiated this study but will move on to take a CNRS position in Montpellier at the end of 2008 before this project can be completed.

感觉系统为生物体提供有关外部世界的信息。例如，声学信息由听觉系统处理，听觉系统涉及耳蜗毛细胞对机械刺激的转导。最后，声学信息在内毛细胞（IHC）的带状突触处被编码。尽管分子生物学和生物物理学的工作已经在带状突触的研究中取得了重大进展，但其分子生理学仍然知之甚少。这个DFG资助的项目的工作提出了一个挑衅性的问题，即这种突触是否采用了典型的神经元陷阱复合物。在大多数突触的胞吐过程中，在三种SNARE蛋白syntaxin 1、synaptobrevin 2和SNAP-25之间形成四螺旋卷曲螺旋蛋白复合物。它是连接囊泡和质膜的桥梁，并被认为是胞吐过程中从对接到融合的一个重要步骤。在第一个资助期间，Regis Nouvian做出了惊人的观察，即IHC中的胞吐作用对梭菌神经毒素E和D具有抗性，在许多其他神经分泌制剂中，梭菌神经毒素E和D分别通过切割SNAP-25和小突触泡蛋白来干扰胞吐作用。此外，在小突触泡蛋白1基因中具有功能突变丧失的小鼠突变体显示正常的IHC胞吐作用，这是出乎意料的，因为小突触泡蛋白1已经在豚鼠IHC中被正式鉴定。当探索SNARE在小鼠IHC中的表达时，我们没有发现神经元SNARE表达的一致证据。该资助更新的目的是通过对SNARE表达的进一步实验（单细胞PCR、免疫组织化学和对敲入小鼠的SNARE荧光标记变体的分析）以及通过进一步测试梭菌神经毒素的作用来鉴定参与IHC胞吐的SNARE。这项工作将在哥廷根与Regis Nouvian合作进行，Regis Nouvian发起了这项研究，但将于2008年底在该项目完成之前在蒙彼利埃担任CNRS的职位。