REGULATION OF EXPRESSION OF EUKARYOTIC INITIATION FACTOR-2 ALPHA

静息状态下人外周血T细胞合成蛋白质的水平非常低 并且含有非常低水平的eIF-2αmRNA。在有丝分裂期间 激活，eIF-2αmRNA水平至少增加50倍， 这种影响被认为主要是由于核内稳定的 主要成绩单。序列(447至457)的分析 第一内含子揭示了一个与启动子(INR)同源的区域 序列最先由斯梅尔和巴尔的摩描述。此INR元素是 定位了eIF-2α启动子下游的450个碱基，并 目的是产生重叠的反义转录本。删除或 INR元件的突变导致可重复的5-8倍增长 在eIF-2α启动子驱动的CAT报告基因的活性中 反义驱动的基因活性相应降低2.5倍 293细胞体内荧光素酶基因报告。体外转录 分析还揭示了依赖于完整的 INR元件，其5‘端映射到INR周围的序列 共识序列。利用DNase I足迹分析和电泳法 迁移率改变分析，我们发现了一个潜在的顺式调节序列 紧挨着457和474之间的INR元素。在……里面 除了提供对DNase I的保护外，还结合了一个43kD 因子还会直接在INR上产生过敏部位 元素。INR元件的反义取向与第一 EIF-2α基因内含子提示反义基因的作用 转录调控eIF-2α的表达。的作用 反义转录本及其43kD蛋白在细胞周期调控中的作用 反义转录目前正在调查中。

Resting human peripheral blood T cells synethesize proteins at very low rates and contain very low levels of eIF-2 alpha mRNA. During mitogenic activation, the level of eIF-2 alpha mRNA increases at least 50-fold, an effect thought to be due primarily to intranuclear stabilization of the primary transcript. Analysis of sequences (+447 to +457) within the first intron revealed a region with homology to the initiator (Inr) sequence first described by Smale and Baltimore. This Inr element is positioned 450 bases downstreams of the eIF-2 alpha promoter and is oriented to generate an overlapping antisense transcript. Deletion or mutation of the Inr element results in a reproducible 5-8 fold increase in the activity of an eIF-2 alpha promoter driven CAT reporter gene and a corresponding 2.5 fold decrease in activity of an antisense driven luciferase report gene in vivo in 293 cells. In vitro transcription analysis also reveals antisense transcripts which depend on an intact Inr element and whose 5' ends map to sequences surrounding the Inr consensus sequence. By DNase I footprint analysis and electrophoretic mobility shift assay, we have found a potential cis-regulatory sequence immediately adjacent to the Inr element between +457 and +474. In addition to conferring protection against DNase I, binding of a 43 kD factor also generates hypersensitive sites directly over the Inr element. The antisense orientation of the Inr element with the first intron of the eIF-2 alpha gene suggests a role for the antisense transcript in the regulation of expression of eIF-2 alpha. The role of antisense transcripts and the role of the 43 kD protein in regulation of antisense transcription are currently under investigation.