Cytosine methylation of an Sp1 site contributes to organ-specific and cell-specific regulation of expression of the lung epithelial gene T1α
Cytosine methylation of an Sp1 site contributes to organ-specific and cell-specific regulation of expression of the lung epithelial gene T1α
复制标题
DOI：
10.1042/bj3500883
复制
发表时间：
2000-09-15
影响因子：
4.1
通讯作者：
Williams, MC
中科院分区：
文献类型：
--
作者：
Cao, YX;Jean, JC;Williams, MC
最近的一些观察表明，胞嘧啶甲基化在正常细胞中细胞特异性基因的体内转录调控中具有作用。我们假设甲基化调节Tier，一种主要在成年啮齿动物肺中表达的基因。在胎儿中，Tier在几个器官中表达，包括整个神经系统，但在发育过程中，其表达逐渐限于肺泡I型上皮细胞、一些成骨细胞和脉络丛。在这里，我们报告这一层。在细胞和器官（包括脑）中的近端启动子中的关键Sp1位点处被甲基化，其中检测不到基因表达。相反，在表达T1 α的细胞中，这些位点没有甲基化。在胚胎脑中，Tier是未甲基化和表达的;在成人脑中，该基因是甲基化和不表达的。在肺上皮细胞系中，T11 α启动子的甲基化在体外使表达降低约10%。50%（最大抑制为100%）。突变的启动子结构的分析表明，一个单一的Sp1位点在近端启动子提供了所有或大部分的甲基化敏感的基因沉默。我们的结论是，除了转录因子的调节，胞嘧啶甲基化有一个完整的动物和原代细胞中该基因的复杂表达模式的作用。
Several recent observations have suggested that cytosine methylation has a role in the in vivo transcriptional regulation of cell-specific genes in normal cells. We hypothesized that methylation regulates Tier, a gene expressed primarily in lung in adult rodents. In fetuses Tier is expressed in several organs, including the entire nervous system, but during development its expression is progressively restricted to lung alveolar type I epithelial cells, some osteoblasts and choroid plexus. Here we report that Tier. is methylated at a key Sp1 site in the proximal promoter in cells and organs, including brain, where no gene expression is detectable. Conversely, in T1 alpha-expressing cells, these sites are not methylated. In embryonic brain Tier is unmethylated and expressed; in adult brain the gene is methylated and not expressed. In lung epithelial cell lines, methylation of the Tl1 alpha promoter in vitro decreases expression by approx. 50% (the maximum suppression being 100%). Analysis of mutated promoter constructs indicates that a single Sp1 site in the proximal promoter provides all or most of the methylation-sensitive gene silencing. We conclude that, in addition to regulation by transcription factors, cytosine methylation has a role in the complex expression patterns of this gene in intact animals and primary cells.