MECHANISMS OF ACETYLCHOLINE RECEPTOR CLUSTERING

细胞表面成分在突触区域的定位是一个重要的 发育神经生物学的问题。 已经表明，横向 弥散表达受体的迁移对 受体聚集在发育中的神经肌肉接头处。 电动 电场提供了一种方便的方法来诱导膜的侧向迁移 组件，它们的使用构成了有用的实验系统， 来研究受体定位。 特别是，培养球形 非洲爪蟾的肌肉细胞已经被证明 集群受体对这些领域作出反应。 集群继续 在电场终止后，对乙酰胆碱具有特异性 受体。 这些观察使其成为一个强大的模型系统， 这是为了探索受体聚集的潜在机制，因为i） 培养的细胞迅速形成受体簇， 可测量的刺激，ii）实验可以在没有 神经突、细胞-基质接触或外源因子，和iii）所述 培养细胞的几何结构简单， 受体密度的定量。 拟议研究的目标是进一步研究 负责模型系统中受体的聚集， 非洲爪蟾文化 实验将利用全球和本地 应用外部电场培养非洲爪蟾肌肉细胞。 在这些操作之后，数字视频显微镜分析 将进行荧光标记的细胞，以表征 乙酰胆碱受体和其他成分的分布。 三大 将讨论以下问题： 1. 什么样的分子事件触发了场诱导的聚集 乙酰胆碱受体？ 2. 其他突触后分子如何对电刺激做出反应？ fields？ 3. 与受体竞争相关的参数是什么？ 邻近的集群？ 对这些问题的研究将增加我们对世界的理解。 负责突触发育形成的体内机制 联系人. 这些问题在知识上至关重要， 发育神经生物学，也具有重要意义， 突触紊乱 受体聚集的根本重要性 从肌无力等疾病的破坏性影响中可以清楚地看到， 严重的，这减少了可用的受体在交界处的数量。 此外，实验结果和理论考虑表明， 神经元竞争受体的机制与 突触连接的发展细化，一个非常感兴趣的话题 关于发展性残疾。

Localization of cell-surface components to synaptic regions is an important problem in developmental neurobiology. It has been shown that lateral migration of diffusely-expressed receptors makes a major contribution to receptor clustering at the developing neuromuscular junction. As electric fields offer a convenient means to induce lateral migration of membrane components, their use constitutes a useful experimental system with which to study receptor localization. In particular, cultures of spherical muscle cells from the African frog Xenopus laevis have been shown to cluster receptors in response to such fields. The clustering continues after the field has been terminated, and is specific for acetylcholine receptors. These observations render this a powerful model system with which to probe the mechanisms underlying receptor clustering, because i) the cultured cells form receptor clusters rapidly in response to precisely measurable stimuli, ii) experiments can be conducted in the absence of neurites, cell-substrate contacts, or exogenous factors, and iii) the cultured cells are geometrically simple, permitting high-resolution quantitation of receptor density. The goal of the proposed study is to examine further the mechanisms responsible for the clustering of receptors in the model system afforded by the Xenopus cultures. The experiments will utilize global and local application of external electric fields to cultured Xenopus muscle cells. Following these manipulations, digital video-microscopic analysis of fluorescently labeled cells will be performed in order to characterize the distribution of acetylcholine receptors and other components. Three broad questions will be addressed: 1. What molecular event(s) trigger the field-induced clustering of acetylcholine receptors? 2. How do other post-synaptic molecules behave in response to electric fields? 3. What are the parameters relevant to competition for receptors between neighboring clusters? Examination of these questions will increase our understanding of the in vivo mechanisms responsible for the developmental formation of synaptic contacts. The questions are intellectually crucial within the context of developmental neurobiology, and also have significance with respect to synapse-based disorders. The fundamental importance of receptor clustering is clear from the devastating effects of diseases such as myasthenia gravis, which reduce the number of available receptors at the junction. Moreover, experimental results and theoretical considerations suggest that the mechanisms by which neurons compete for receptors relate to the developmental refinement of synaptic connections, a topic of great interest with respect to developmental disabilities.