REGULATION OF NEURONAL NICOTINIC ACETYLCHOLINE RECEPTOR

分子克隆研究已经确定了基因家族 编码功能不同的异构体配基门控离子通道。 一个这样的基因家族编码亚基，这些亚基组装成几个 功能不同的异构体神经元烟碱乙酰胆碱 感受器。烟碱受体亚单位基因家族丰富 在脊椎动物的大脑和周围神经系统中表达。每个人 成员有一个独特的表达模式，尽管这些模式 部分重叠。因此，该基因家族很可能编码多个 异构体受体在许多细胞中抑制突触功能 大脑和外周的胆碱能通路。 该提案涉及确定以下机制 控制脊椎动物受体亚单位基因的表达，从而在功能上 不同的异构型尼古丁受体可以组装在不同的 表型不同的神经元的亚群。所描述的实验如下 旨在：1)识别控制神经元的顺式作用元件 尼古丁受体亚单位基因以神经特异的方式转录， 2)测定NGF对烟碱受体亚单位的影响 RNA在转录或RNA稳定的水平上发挥作用，3) 确定活性对受体亚单位基因表达的影响， 以及4)确定受体亚单位基因表达是否发生变化 在突触快速发生的时期。编码神经元的基因家族 尼古丁受体亚单位特别容易受到建议的 调查，因为它的成员在一个很有特色的 克隆细胞系PC12及其在可及实验中的应用 可操控的交感神经系统。PC12系列产品提供了 一种方便的细胞培养系统，可在其中开始表征 控制配基门控离子通道的转录调控元件 基因。交感神经节提供了一个可接近的实验系统 补充的原代神经元在体内和体外的方法 细胞间相互作用对受体亚单位基因的影响 表情。神经元型烟碱受体亚单位基因及其他 配基门控离子通道基因在许多细胞核和细胞中共表达 大脑的各个层面。常见的神经元环境增加了这种可能性 编码不同配体门控离子通道的基因有相似之处 监管机制。因此，这项调查很可能成为 一个调节其他配体门控离子通道基因的模型， 哪些具有良好特征且易于访问的实验模型系统不是 也很发达。 烟碱受体基因表达的研究将 最终导致对受体基因重要性的理解 神经系统发育的调节机制，也许 对神经系统疾病的分子机制的洞察 由异常发育造成的。

Molecular cloning studies have identified gene families encoding functionally distinct heteromeric ligand-gated ion-channels. One such family of genes encodes subunits that are assembled into several functionally-distinct heteromeric neuronal nicotinic acetylcholine receptors. The nicotinic receptor subunit gene family is abundantly expressed in the vertebrate brain and peripheral nervous system. Each member has a unique pattern of expression, although these patterns overlap partially. Thus, this gene family is likely to encode multiple heteromeric receptors to subserve synaptic functions in numerous cholinergic pathways of the brain and periphery. This proposal is concerned with identifying the mechanisms that control vertebrate receptor subunit gene expression so that functionally distinct heteromeric nicotinic receptors can be assembled in different subsets of phenotypically distinct neurons. The experiments described are designed to: 1) identify the cis-acting elements that control neuronal nicotinic receptor subunit gene transcription in a neural-specific manner, 2) determine whether the influence of NGF on nicotinic receptor subunit RNAs is exerted at the level of transcription or RNA stability, 3) determine the influence of activity on receptor subunit gene expression, and 4) determine if changes in receptor subunit gene expression occur during periods of rapid synaptogenesis. The gene family encoding neuronal nicotinic receptor subunits are particularly amenable to the proposed investigation because its members are expressed in a wellcharacterized clonal cell line, PC12 and in the accessible and experimentally manipulatable sympathetic nervous system. The PC12 line provides a convenient cell culture system in which to begin characterizing transcription regulatory elements controlling ligand-gated ion-channel genes. Sympathetic ganglia provide an accessible experimental system of primary neurons for complementary in vivo and in vitro approaches to address the influence of cell-cell interactions on receptor subunit gene expression. Neuronal nicotinic receptor subunit genes and other ligand-gated ion-channel genes are co-expressed in numerous nuclei and cell layers of the brain. Common neuronal environments raise the possibility that the genes encoding different ligand-gated ion-channels share similar mechanisms of regulation. Thus, this investigation is likely to serve as a model for the regulation of other ligand-gated ion-channel genes, for which well-characterized and accessible experimental models systems are not as well developed. The investigation of nicotinic receptor gene expression will ultimately lead to an understanding of the importance of receptor gene regulatory mechanisms to the development of the nervous system and perhaps insight into the molecular mechanisms of neurological disorders which result from aberrant development.