生物谷報(bào)道：最新研究表明基因的表達(dá)嚴(yán)格按照基因組的調(diào)節(jié),。表觀遺傳包括很多信息并沒(méi)有出現(xiàn)在DNA序列之中,，在發(fā)育過(guò)程中環(huán)境限制了一部分基因的表達(dá),。DNA序列中CpGs結(jié)構(gòu)的甲基化對(duì)表觀遺傳的調(diào)節(jié)具有顯著作用,，它可以使染色體轉(zhuǎn)錄沉默。甲基化作用可以使基因組在細(xì)胞分裂過(guò)程中保持穩(wěn)定。最近研究發(fā)現(xiàn)一種動(dòng)力在人類(lèi)細(xì)胞DNA甲基化過(guò)程中起到重大作用,。人類(lèi)雌性激素可作用于pS2/TFF1基因的啟動(dòng)子,，通過(guò)調(diào)節(jié)甲基化和去甲基化影響基因表達(dá)。DNA甲基化同時(shí)通過(guò)脫氨出現(xiàn)在CpG和5mCpGs結(jié)構(gòu)中,。這種抑制作用不影響pS2基因啟動(dòng)子序列的甲基化和其后隨序列的活性,。CpGs結(jié)構(gòu)啟動(dòng)子通過(guò)周期性的DNA甲基化狀態(tài)調(diào)節(jié)轉(zhuǎn)錄產(chǎn)物使基因表達(dá)多樣化。(生物谷 趙晨光)
生物谷推薦原始出處:
Nature 452, 45-50 (6 March 2008) | doi:10.1038/nature06544; Received 21 September 2007; Accepted 12 December 2007
Cyclical DNA methylation of a transcriptionally active promoter
Raphaël Métivier, Rozenn Gallais, Christophe Tiffoche, Christine Le Péron, Renata Z. Jurkowska, Richard P. Carmouche, David Ibberson, Peter Barath, Florence Demay, George Reid, Vladimir Benes, Albert Jeltsch, Frank Gannon& Gilles Salbert
Processes that regulate gene transcription are directly under the influence of the genome organization. The epigenome contains additional information that is not brought by DNA sequence, and generates spatial and functional constraints that complement genetic instructions. DNA methylation on CpGs constitutes an epigenetic mark generally correlated with transcriptionally silent condensed chromatin. Replication of methylation patterns by DNA methyltransferases maintains genome stability through cell division. Here we present evidence of an unanticipated dynamic role for DNA methylation in gene regulation in human cells. Periodic, strand-specific methylation/demethylation occurs during transcriptional cycling of the pS2/TFF1 gene promoter on activation by oestrogens. DNA methyltransferases exhibit dual actions during these cycles, being involved in CpG methylation and active demethylation of 5mCpGs through deamination. Inhibition of this process precludes demethylation of the pS2 gene promoter and its subsequent transcriptional activation. Cyclical changes in the methylation status of promoter CpGs may thus represent a critical event in transcriptional achievement.
