MECHANISMS OF ACETYLCHOLINE RECEPTOR CLUSTERING

细胞表面成分定位到突触区域是一个重要的 发育神经生物学中的问题。已经证明，横向 弥漫性表达的受体的迁移对 受体聚集在发育中的神经肌肉连接处。作为电动的 电场提供了一种方便的方法来诱导膜的横向迁移 组件，它们的使用构成了一个有用的实验系统， 研究受体的定位。特别是，球形的培养物 非洲爪蛙的肌肉细胞已经被证明是 对这样的磁场作出反应的受体。群集将继续 在字段已经终止之后，并且是特定于乙酰胆碱的 感受器。这些观察结果使其成为一个功能强大的模型系统 这是为了探索受体聚集的机制，因为我) 培养的细胞迅速形成受体簇，以准确地响应 可测量的刺激，II)实验可以在没有 神经突起、细胞-底物接触或外源性因素，以及iii) 培养的细胞在几何上很简单，允许高分辨率 受体密度的定量。 拟议研究的目标是进一步研究这些机制。 负责模型系统中受体的集群，由 非洲爪哇文化。这些实验将利用全局和局部 外加电场在非洲爪哇肌肉细胞培养中的应用。 在这些操作之后，数字视频显微分析 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。三宽 这些问题将会得到解答： 1.什么分子事件(S)触发了场诱导的群聚 乙酰胆碱受体？ 2.其他突触后分子对电的反应如何 菲尔兹？ 3.与受体竞争有关的参数有哪些 邻近星团？ 对这些问题的考查将加深我们对 突触发育形成的活体机制 联系人。在以下背景下，这些问题在智力上至关重要 发育神经生物学，并且在以下方面也有意义 基于突触的障碍。受体聚集的基本重要性 从像肌无力这样的疾病的破坏性影响中可以清楚地看到 Gravis，这会减少交界处可用的受体数量。 此外，实验结果和理论考虑表明， 神经元竞争受体的机制与 突触连接的发育完善，这是一个非常有趣的话题 关于发育障碍的问题。

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.