Li Y, Camp S, Rachinsky T L, Bongiorno C, Taylor P
Department of Pharmacology, University of California, San Diego, La Jolla 92093-0636.
J Biol Chem. 1993 Feb 15;268(5):3563-72.
The 5'-untranslated region of the mouse acetylcholinesterase gene has been characterized structurally by RNase protection, primer extension, and sequencing. Evidence has been obtained for the use of two alternative promoters in brain. Tissue-specific splicing to alternative acceptor sites in the 5'-untranslated exons occurs in brain, muscle, and erythropoietic cells. cis elements 5' of the cap site that is predominantly used in these tissues and cells have been analyzed by deletion analysis of promoter-reporter gene constructs and by site-specific mutagenesis. The cap site is found 107 base pairs (bp) 5' of the translation start site. This region is devoid of CAAT or TATA sequences; further in the 5' direction 50 and 70 bp are tandem Egr-1 sites. The putative promoter has been coupled to the open reading frame of a luciferase reporter gene. Deletion analysis shows that this region largely accounts for tissue-specific transcription seen upon transfection of neuronal and muscle cells. Mutagenesis of the Egr-1 sites results in a marked loss of reporter gene activity, further substantiating the importance of this region in the control of transcription. cis elements in the promoter differ from those found for the genes encoding the various subunits of the nicotinic acetylcholine receptor, and distinct differences in control of transcription are evident when the respective reporter genes are transfected into C2 muscle cells.
小鼠乙酰胆碱酯酶基因的5'-非翻译区已通过核糖核酸酶保护、引物延伸和测序进行了结构表征。已获得证据表明在大脑中使用了两个替代启动子。在大脑、肌肉和造血细胞中发生了向5'-非翻译外显子中替代受体位点的组织特异性剪接。通过启动子-报告基因构建体的缺失分析和位点特异性诱变，分析了在这些组织和细胞中主要使用的帽位点5'端的顺式元件。帽位点位于翻译起始位点5'端107个碱基对（bp）处。该区域没有CAAT或TATA序列；在5'方向上更远的位置，50和70 bp处是串联的Egr-１位点。推定的启动子已连接到荧光素酶报告基因的开放阅读框。缺失分析表明，该区域在很大程度上解释了在神经元和肌肉细胞转染后所见的组织特异性转录。Egr-１位点的诱变导致报告基因活性明显丧失，进一步证实了该区域在转录控制中的重要性。启动子中的顺式元件与编码烟碱型乙酰胆碱受体各个亚基的基因中的顺式元件不同，当将各自的报告基因转染到C2肌肉细胞中时，转录控制中的明显差异很明显。
