DIFFERENTIATION AND REGULATION OF GENE EXPRESSION IN ASTROCYTES AND NEURONS

星形胶质细胞和神经元基因表达的分化和调控

• 批准号: 3881756
• 负责人: E FREESE
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF NEUROLOGICAL DISORDERS AND STROKE
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3881756
• 关键词: Anura; DNA directed RNA polymerase; astrocytes; calcium channel; complementary DNA; extracellular matrix; gene expression; genetic regulation; genetic regulatory element; genetic transcription; glial fibrillary acidic protein; glutamate decarboxylase; glutamate receptor; glutaminase; growth cones; laboratory rat; laminin; messenger RNA; molecular cloning; nerve /myelin protein; neurons; nucleic acid sequence; oligonucleotides; protein sequence; protein structure; reporter genes; transfection; voltage gated channel

The genes for a number of neurologically important proteins have been isolated and sequenced, and their control mechanisms are being studied. In particular, we want to understand why certain genes are expressed in neurons but not in astrocytes and vice versa. Laminin is a component of the extracellular matrix of astrocytes and promotes neurite outgrowth. In basal lamina cells laminin normally consists of 3 chains (A, Bl, B2). Using chain-specific antibodies and small cDNAs, we have shown that astrocytes make only the B2 mRNA and protein of laminin. The promoter region responsible for this specificity has been localized within 200 bp of the B2 gene. Glial fibrillary acidic protein (GFAP) is an intermediate filament protein found only in mature astrocytes. It is transcribed by RNA polymerase 11 but, in contrast to other genes, uses as promoter not only a TATA box 25 bp upstream of the start site but also a downstream element 10 to 50 bp distant. Glutamine synthetase (GS) converts glutamate to glutamine which then enters neurons and is converted to glutamate or GABA. The promoter for the GS gene contains a TATA box, 28 bp upstream from the transcription start site. Sequences with homology to cAMP and glucocorticoid response elements have also been found. Deletion mutants with the GS promoter and a CAT reporter gene have been constructed and transfected into several cell lines in order to examine the functional significance of the regulatory sequences. Genomic clones and cDNAs for the L-type calcium channel gene have been obtained. At least 4 forms of the alpha-l subunit of the channel are expressed. Hybridization experiments reveal high levels of neuron-specific calcium channel mRNA in the olfactory bulb, hippocampal CAl (ells, dentate gyrus, suprachiasmatic nucleus, and the medial preoptic nucleus. Other sites also expressed activity. Work is continuing toward isolating a human calcium gene.

许多神经学上重要的蛋白质的基因已经被 分离并测序，其控制机制正在研究中。在 特别是，我们想知道为什么某些基因在 而不是在星形胶质细胞，反之亦然。层粘连蛋白是 星形胶质细胞的细胞外基质，并促进神经突生长。在 基底层细胞层粘连蛋白通常由3条链（A、B1、B2）组成。 使用链特异性抗体和小cDNA，我们已经表明， 星形胶质细胞仅产生层粘连蛋白的B2 mRNA和蛋白。启动子 负责这种特异性的区域已经定位在200 bp以内 B2基因。胶质细胞酸性蛋白（GFAP）是一种 仅在成熟星形胶质细胞中发现的丝蛋白。它由RNA转录 聚合酶11，但与其他基因相反，它不仅用作启动子， 起始位点上游25 bp的TATA盒，但也是下游元件10 到50 bp远。谷氨酰胺合成酶（GS）将谷氨酸转化为 谷氨酰胺然后进入神经元并转化为谷氨酸或GABA。 GS基因的启动子含有TATA盒，位于GS基因上游28 bp处。 转录起始位点。与cAMP具有同源性的序列， 糖皮质激素反应元件也被发现。 构建了具有GS启动子和CAT报告基因的表达载体， 转染到几个细胞系，以检查功能 调控序列的重要性。基因组克隆和cDNA， L型钙通道基因已获得。至少有4种形式的 表达通道的α-l亚基。杂交实验 揭示了高水平的神经元特异性钙通道mRNA， 嗅球、海马CA 1区（细胞、齿状回、视交叉上核 核和内侧视前核。其他网站也表示， 活动分离人类钙基因的工作仍在继续。