MECHANISMS OF ACETYLCHOLINE RECEPTOR AGGREGATION IN A SIMPLE MODEL SYSTEM

将细胞表面成分定位到突触区域是一种 发育神经生物学中的重要问题。事实证明， 弥漫性表达的受体的侧向迁移成为主要的 发育中的神经肌肉对受体聚集的贡献 交叉口。因为电场提供了一种方便的方法来诱导横向 膜组件的迁移，它们的使用构成了一种有用的 用于研究受体定位的实验系统。在……里面 非洲青蛙球状肌肉细胞的培养 非洲爪哇已被证明能聚集受体，以响应这种 菲尔兹。在该字段已被终止之后继续聚类， 并且对乙酰胆碱受体是特异的。这些观察结果呈现了 这是一个强大的模型系统，可以用来探索机制 潜在的受体聚集，因为i)培养的细胞形成 受体迅速聚集以响应精确可测量的刺激， Ii)实验可以在没有神经突起、细胞- 底物接触，或外源因素，以及iii)培养的细胞 几何结构简单，允许对受体进行高分辨率定量 密度。 拟议研究的目标是进一步研究这些机制。 负责提供的模型系统中受体的集群 被非洲爪哇文化。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 乙酰胆碱受体及其他成分的分布。三 我们将讨论广泛的问题： 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。在上下文中，这些问题在智力上是至关重要的 对发育神经生物学的研究，也具有重要的意义 以突触为基础的障碍。受体的根本重要性 从疾病的破坏性影响来看，聚集性是显而易见的 重症肌无力，这会减少可用受体的数量 交叉口。此外，实验结果和理论考虑。 提示神经元竞争受体的机制与 对于突触连接的发育完善，一个非常重要的话题 对发育障碍的兴趣。

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 distributions 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.