DIFFERENTIATION AND REGULATION OF GENE EXPRESSION IN ASTROCYTES AND NEURONS

许多神经学上重要蛋白质的基因已经被 分离和测序，它们的控制机制正在研究中。在……里面 具体地说，我们想了解为什么某些基因在 但不存在于星形胶质细胞中，反之亦然。层粘连蛋白是一种 星形胶质细胞的细胞外基质，并促进轴突生长。在……里面 基板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的cDNA，我们已经证明 星形胶质细胞只产生层粘连蛋白的B2mRNA和蛋白质。推动者 负责此特异性的区域已定位在200个BP以内 B2基因的基因。胶质纤维酸性蛋白(GFAP)是一种 仅在成熟的星形胶质细胞中发现的丝状蛋白。它是由RNA转录的 但与其他基因不同的是，聚合酶11不仅用作启动子 塔塔盒子25个基点，位于起始点上游，但也是下游元件10 到50BP的距离。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，转化为谷氨酸或GABA。 GS基因的启动子含有一个TATA盒，位于 转录起始点。与cAMP和cAMP同源的序列 糖皮质激素反应元件也被发现。缺失突变体 已经构建了GS启动子和CAT报告基因，并 将其导入多个细胞系，以检测其功能 调控序列的意义。的基因组克隆和cDNA 已获得L型钙通道基因。最少4种形式的 α-L通道亚基均有表达。杂交实验 揭示了神经元特异性钙通道基因的高水平表达。 嗅球、海马CA1区(细胞、齿状回、视交叉上回 核团和内侧视前核团。其他网站也表达了 活动。分离人类钙基因的工作仍在继续。

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.