DEVELOPMENTAL EXPRESSION OF GABA-A RECEPTOR MRNAS

描述（来自申请人摘要的逐字）：这些的长期目标 研究的目的是确定参与的分子事件和信号级联反应， 小脑颗粒神经元GABAA受体亚单位表达的调控 分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，它们停止在外部生殖器中分裂。 层（EGL），迁移到内部颗粒层中的成熟位置 (IGL)并接收突触输入。一个表型变化伴随着这一点， 成熟过程是六种mRNA编码亚基的表达增加 GABAA受体。这种多亚基配体门控离子通道受体 介导γ-氨基丁酸的作用， 神经传递素尽管在时间上同时增加， 在体内亚单位转录水平，使用培养的颗粒神经元的研究， 导致亚基表达受到差异调节的假设， 依赖于多种调节信号。小脑环境中的信号 选择性诱导GABAA受体β 2和δ亚基表达， 培养的颗粒神经元最近已被鉴定。探讨 这些信号的作用，提出了以下研究。一是 Neuregulin和小脑EGL提取物对β 2亚基的调节作用 GABAA受体的表达和功能将在颗粒细胞培养物中进行检测。 用Western blotting、免疫细胞化学和RT-PCR检测神经元。的 EGL提取物的作用由神经调节蛋白介导的可能性将 被确定。电生理学研究将调查是否 亚基表达的改变与以下反应的变化相关： GABA第二，神经元活动和谷氨酸的作用机制 受体活化调节δ亚单位表达和GABAA受体 功能将使用类似的实验方法进行检查。研究将 在存在或不存在脑桥的情况下生长的小脑切片上进行 外植体，体内发现的兴奋性苔藓纤维输入的来源。三、信号 介导亚基表达变化的转导途径将是 鉴定总之，这些研究将产生新的信息， 参与指导发育表达的环境信号， 调节神经元群体中的GABAA受体。

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.