Development and Regulation of Cholinergic Synapses

描述（由申请人提供）：我们的长期科学目标是获得突触传递的机制理解，重点是乙酰胆碱受体的建立和调节。快速胆碱能神经传递在肌肉和大脑是通过突触释放乙酰胆碱（ACh），它结合并激活离子通道形成五聚体受体（achr）。这些受体在进化上是保守的，无脊椎动物和脊椎动物都表达大量的AChR亚基，它们可以形成异质或同源的AChR。不同的受体对药物（如成瘾药物尼古丁）表现出不同的敏感性，受体的多样性有助于神经元功能和药物依赖。其中一种受体，即a7achr，与自闭症、焦虑和精神分裂症有关。a7介导的神经传递强度严重依赖于a7 achr的定位和密度；然而，这些受体或任何achr是如何被传递到突触并定位在突触上的，仍然没有得到很好的理解。本研究的目的是通过在秀丽隐杆线虫中使用遗传方法来识别有助于a7样achr传递或功能的信号通路，从而获得achr介导的突触信号传导的机制理解。我们之前证明了由秀丽隐杆线虫a7的同系物ACR-16介导的突触电流依赖于CAM-1，一种Ror类受体酪氨酸激酶（RTK）。我们现在有初步的数据表明，编码Wnt介导的信号传导蛋白的三个基因（CWN-2/Wnt， LIN-17/Fzd和DSH-1/Dvl）的突变表型与cam-1突变体中发现的行为和电生理缺陷有关。在本文中，我们测试了所有四种蛋白质都参与wnt介导的信号通路的模型，该信号通路是突触ACR-16受体的传递、定位或功能所必需的，我们阐明了下游信号传导成分，并测量了受体运输的体内动态。胆碱能神经传递与尼古丁成瘾、记忆和认知有关。a7 AChR调节和功能的扰动被认为是导致广泛的神经疾病的原因，如自闭症、焦虑、精神分裂症，以及阿尔茨海默病和帕金森病。因为许多对突触传递重要的基因产物在无脊椎动物到脊椎动物之间是保守的，我们预测，我们从秀丽隐杆线虫的研究中学到的东西将与正在进行的脊椎动物神经系统的研究直接相关。因此，我们的研究努力可能最终导致与胆碱能神经传递缺陷相关的神经疾病的新诊断或治疗方式。

DESCRIPTION (provided by applicant): Our long-term scientific goal is to gain a mechanistic understanding of synaptic transmission, with a focus on the establishment and regulation of acetylcholine receptors. Rapid cholinergic neurotransmission at muscles and in the brain is via synaptically released acetylcholine (ACh), which binds to and activates ion-channel forming pentameric receptors (AChRs). These receptors are evolutionarily conserved, and invertebrate and vertebrate organisms express large families of AChR subunits, which can form heteromeric or homomeric AChRs. The various receptors exhibit differential sensitivity to drugs (such as the addictive drug nicotine), and the diversity of receptors contributes to neuronal function and drug dependence. One receptor in particular, the homomeric a7 AChR, is associated with autism, anxiety and schizophrenia. The strength of a7-mediated neurotransmission is critically dependent on the localization and density of a7 AChRs; however, how these receptors or any AChRs are delivered to and localized at synapses is still not well understood. The goal of this proposal is to gain a mechanistic understanding of AChR-mediated synaptic signaling by using a genetic approach in Caenorhabditis elegans to identify signaling pathways that contribute to the delivery or function of a7-like AChRs. We previously demonstrated that synaptic currents mediated by ACR-16, a C. elegans a7 homologue, are dependent on CAM-1, a Ror class receptor tyrosine kinase (RTK). We now have preliminary data demonstrating that mutations in three genes encoding proteins that contribute to Wnt-mediated signaling (CWN-2/Wnt, LIN-17/Fzd, and DSH-1/Dvl) phenocopy the behavioral and electrophysiological defects found in cam-1 mutants. In this proposal we test the model that all four proteins contribute to a Wnt-mediated signaling pathway that is required for the delivery, localization or function of synaptic ACR-16 receptors, we elucidate downstream signaling components, and we measure the in vivo dynamics of receptor trafficking. Cholinergic neurotransmission is implicated in nicotine addiction, memory and cognition. Perturbations in a7 AChR regulation and function are thought to contribute to a broad spectrum of neuronal disorders such as autism, anxiety, and schizophrenia, as well as Alzheimer's and Parkinson's diseases. Because many of the gene products important for synaptic transmission are conserved from invertebrates to vertebrates, we predict that what we learn from our studies in C. elegans will have immediate relevance to ongoing studies in the vertebrate nervous system. Thus, our research efforts might ultimately lead to new diagnostic or therapeutic modalities for neuronal disorders associated with defects in cholinergic neurotransmission.