DEVELOPMENTAL EXPRESSION OF GABA-A RECEPTOR MRNAS

描述(逐字摘自申请者摘要)：这些项目的长期目标 研究是确定分子事件和信号级联涉及 小脑颗粒神经元GABAA受体亚单位表达的调节 差异化。小脑颗粒神经元在出生后经历广泛的 成熟。在这个过程中，它们停止了在外部胚芽中的分裂 层(EGL)，迁移到它们在内部颗粒层中的成熟位置 (IGL)，并接受突触输入。随之而来的一个表型变化 成熟过程是六个编码亚基的mRNAs表达增加 GABAA受体。这种多亚单位、配体门控的离子通道受体 介导主要抑制物--γ-氨基丁酸的作用 大脑中的神经递质。尽管在时间上同时增加了 体内亚单位转录水平的研究，使用培养的颗粒神经元 导致了亚基表达受到差异调控的假说 依赖于多个监管线索。小脑环境中的信号 选择性地诱导GABAA受体β2和Delta亚基的表达 培养中的颗粒神经元最近被鉴定出来。为了调查 对于这些信号的作用，提出了以下研究建议。首先， 神经调节蛋白和小脑EGL提取物对β2亚单位的调节作用 GABAA受体的表达和功能将在颗粒培养中进行检测 用Western blotting、免疫细胞化学和RT-PCR检测神经元。这个 EGL提取物的作用可能是由NeuRegin Will介导的 要下定决心。电生理学研究随后将调查 亚基表达的变化与对 GABA。第二，神经元活动和谷氨酸的作用机制 受体激活在调节Delta亚基表达和GABAA受体中的作用 功能将使用类似的实验方法进行检验。研究将会 在存在或不存在脑桥的情况下生长的小脑片上进行手术 外植体是体内发现的兴奋性苔藓纤维输入的来源。第三，信号 介导亚单位表达变化的转导通路将是 已确认身份。总之，这些研究将产生关于以下方面的新信息 环境信号参与指导发育表达和 神经细胞群体中GABAA受体的调节。

DESCRIPTION(Verbatim from Applicant's Abstract): The long term goal of these studies is to identify molecular events and signaling cascades involved in regulating GABAA receptor subunit expression during cerebellar granule neuron differentiation. Cerebellar granule neurons undergo extensive postnatal maturation. During this process they cease dividing in the external germinal layer (EGL), migrate to their mature positions in the internal granule layer (IGL), and receive synaptic input. One phenotypic change accompanying this maturation process is the increased expression of six mRNAs encoding subunits of the GABAA receptor. This multisubunit, ligand-gated ion channel receptor mediates the actions of gamma-aminobutyric acid, the major inhibitory neurotransmitter in the brain. Despite the temporally concurrent increases in subunit transcript levels in vivo, studies using cultured granule neurons have led to the hypothesis that subunit expression is differentially regulated and dependent on multiple regulatory cues. Signals in the cerebellar environment which selectively induce GABAA receptor beta2 and delta subunit expression in granule neurons in culture have recently been identified. To investigate the actions of these signals, the following studies are proposed. First, the actions of neuregulin and cerebellar EGL extracts in regulating beta2 subunit expression and GABAA receptor function will be examined in cultures of granule neurons using Western blotting, immunocytochemistry, and RT-PCR. The possibility that the effects of the EGL extract are mediated by neuregulin will be determined. Electrophysiological studies will then investigate whether alterations in subunit expression are correlated with changes in response to GABA. Second, the mechanisms of action of neuronal activity and glutamate receptor activation in regulating delta subunit expression and GABAA receptor function will be examined using similar experimental approaches. Studies will be performed on cerebellar slices grown in the presence or absence of pons explants, a source of excitatory mossy fiber input found in vivo. Third, signal transduction pathways mediating the changes in subunit expression will be identified. Together, these studies will yield novel information concerning environmental signals involved in directing the developmental expression and regulation of the GABAA receptor in a neuronal population.