REGULATION OF NEURONAL NICOTINIC ACETYLCHOLINE RECEPTOR

分子克隆研究已经确定了基因家族 编码功能不同的异聚体配体门控离子通道。 一个这样的基因家族编码亚基， 功能不同的异聚神经元烟碱乙酰胆碱 受体。 烟碱受体亚单位基因家族在 在脊椎动物脑和周围神经系统中表达。 每个 成员有一个独特的表达模式，虽然这些模式 部分重叠。 因此，该基因家族可能编码多个 异聚体受体，以维护突触功能，在许多 脑和外周的胆碱能通路。 这项建议涉及到确定 控制脊椎动物受体亚单位基因表达， 不同的异聚体烟碱受体可以在不同的细胞中组装， 表型不同的神经元的子集。 所描述的实验是 目的是：1）鉴定控制神经元的顺式作用元件 烟碱受体亚单位基因以神经特异性方式转录， 2)确定NGF是否影响烟碱受体亚单位 RNA在转录或RNA稳定性水平发挥作用，3） 确定活性对受体亚单位基因表达的影响， 以及4）确定受体亚基基因表达是否发生变化 在快速突触形成的时期。 编码神经元的基因家族 烟碱受体亚单位特别适合于所提出的 调查，因为它的成员是表达在一个良好的特点， 克隆细胞系，PC12和在可获得的和实验 交感神经系统 PC12系列提供了 开始表征的方便的细胞培养系统 调控配体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， 原代神经元，用于补充体内和体外方法， 探讨细胞间相互作用对受体亚基基因的影响 表情 神经元尼古丁受体亚单位基因和其他 配体门控离子通道基因在许多细胞核和细胞内共表达， 大脑的各个层 共同的神经元环境提高了 编码不同配体门控离子通道的基因有相似的 监管机制。 因此，这项调查很可能会成为 其他配体门控离子通道基因调控的模型， 哪些特征良好且易于使用的实验模型系统不是 发展良好。 烟碱受体基因表达的研究将有助于 最终使人们了解受体基因的重要性， 神经系统发育的调节机制， 深入了解神经系统疾病的分子机制， 是由异常的发展造成的。

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.