美國(guó)科學(xué)家14日公布首張人類表觀基因組圖譜,。這一成果將對(duì)人類表觀遺傳學(xué)研究作出貢獻(xiàn)。表觀遺傳學(xué)被稱為基因,、疾病和環(huán)境之間“迷失的橋梁”,。
美國(guó)薩克研究所（Salk）的研究人員利用功能強(qiáng)大的計(jì)算機(jī)和新技術(shù)繪制了兩種人類細(xì)胞的表觀基因組圖譜，它們分別為胚胎干細(xì)胞和肺部纖維原細(xì)胞,。
索爾克生物研究所研究員約瑟夫·?？苏f(shuō)：“以往，我們僅局限于表觀基因組片段圖,。能夠研究表觀基因組的全部圖譜將方便我們更好地體會(huì)基因組究竟如何影響健康和疾病,，也可以使我們明白飲食和環(huán)境如何作用于基因表達(dá)。”
表觀遺傳學(xué)是與遺傳學(xué)相對(duì)應(yīng)的概念,。遺傳學(xué)是指基于基因序列改變所致基因表達(dá)水平變化,；而在不改變脫氧核糖核酸（DNA）序列的情況下，激活和關(guān)閉基因行為或使之低調(diào)發(fā)揮的機(jī)制,，稱作“表觀遺傳”,。
每個(gè)生物體都有一個(gè)基本的表觀基因組，相當(dāng)于控制基因功能的“使用手冊(cè)”,。生物體通過(guò)與環(huán)境互動(dòng)編輯“使用手冊(cè)”,，不斷添加或刪除“使用說(shuō)明”,。換句話說(shuō)，我們?nèi)粘Ｋ缘氖澄锘蚪佑|的毒素都可對(duì)激活或關(guān)閉基因行為產(chǎn)生遺傳性改變,。
這份研究報(bào)告刊登于英國(guó)《自然》雜志網(wǎng)絡(luò)版上,。（生物谷Bioon.com）
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生物谷推薦原始出處：
Nature advance online publication 14 October 2009 | doi:10.1038/nature08514
Human DNA methylomes at base resolution show widespread epigenomic differences
Ryan Lister1,9, Mattia Pelizzola1,9, Robert H. Dowen1, R. David Hawkins2, Gary Hon2, Julian Tonti-Filippini4, Joseph R. Nery1, Leonard Lee2, Zhen Ye2, Que-Minh Ngo2, Lee Edsall2, Jessica Antosiewicz-Bourget5,6, Ron Stewart5,6, Victor Ruotti5,6, A. Harvey Millar4, James A. Thomson5,6,7,8, Bing Ren2,3 & Joseph R. Ecker1
1 Genomic Analysis Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
2 Ludwig Institute for Cancer Research,
3 Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, California 92093, USA
4 ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, Crawley, Western Australia 6009, Australia
5 Morgridge Institute for Research, Madison, Wisconsin 53707, USA
6 Genome Center of Wisconsin, Madison, Wisconsin 53706, USA
7 Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, Wisconsin 53715, USA
8 Department of Anatomy, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
9 These authors contributed equally to this work.
10 Correspondence to: Joseph R. Ecker1 Correspondence and requests for materials should be addressed to J.R.E.
DNA cytosine methylation is a central epigenetic modification that has essential roles in cellular processes including genome regulation, development and disease. Here we present the first genome-wide, single-base-resolution maps of methylated cytosines in a mammalian genome, from both human embryonic stem cells and fetal fibroblasts, along with comparative analysis of messenger RNA and small RNA components of the transcriptome, several histone modifications, and sites of DNA–protein interaction for several key regulatory factors. Widespread differences were identified in the composition and patterning of cytosine methylation between the two genomes. Nearly one-quarter of all methylation identified in embryonic stem cells was in a non-CG context, suggesting that embryonic stem cells may use different methylation mechanisms to affect gene regulation. Methylation in non--CG contexts showed enrichment in gene bodies and depletion in protein binding sites and enhancers. Non--CG methylation disappeared upon induced differentiation of the embryonic stem cells, and was restored in induced pluripotent stem cells. We identified hundreds of differentially methylated regions proximal to genes involved in pluripotency and differentiation, and widespread reduced methylation levels in fibroblasts associated with lower transcriptional activity. These reference epigenomes provide a foundation for future studies exploring this key epigenetic modification in human disease and development.
