H3K4me3 inversely correlates with DNA methylation at a large class of non-CpG-island-containing start sites
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- 作者：Dheepa Balasubramanian (1)
Batool Akhtar-Zaidi (1) (2)
Lingyun Song (3)
Cynthia F Bartels (1)
Martina Veigl (4)
Lydia Beard (4)
Lois Myeroff (4)
Kishore Guda (4)
James Lutterbaugh (4)
Joseph Willis (4) (5)
Gregory E Crawford (3)
Sanford D Markowitz (1) (4) (6)
Peter C Scacheri (1) (2) (4) - 刊名：Genome Medicine
- 出版年：2012
- 出版时间：May 2012
- 年：2012
- 卷：4
- 期：5
- 全文大小：
- 作者单位：Dheepa Balasubramanian (1)
Batool Akhtar-Zaidi (1) (2)
Lingyun Song (3)
Cynthia F Bartels (1)
Martina Veigl (4)
Lydia Beard (4)
Lois Myeroff (4)
Kishore Guda (4)
James Lutterbaugh (4)
Joseph Willis (4) (5)
Gregory E Crawford (3)
Sanford D Markowitz (1) (4) (6)
Peter C Scacheri (1) (2) (4)
1. Department of Genetics and Genome Sciences, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH, 44106, USA
2. Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, 9500 Euclid Ave, Cleveland, OH, 44195, USA
3. Institute for Science and Policy, and Department of Pediatrics, Duke University, 101 Science Drive, Durham, NC, 27708, USA
4. Case Comprehensive Cancer Center, Case Western Reserve University, 11100 Euclid Ave, Cleveland, OH, 44106, USA
5. Department of Pathology, Case Western Reserve University, 2103 Cornell Road, Cleveland, OH, 44106, USA
6. Department of Medicine, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH, 44106, USA - ISSN：1756-994X
文摘
Background In addition to mutations, epigenetic silencing of genes has been recognized as a fundamental mechanism that promotes human carcinogenesis. To date, characterization of epigenetic gene silencing has largely focused on genes in which silencing is mediated by hypermethylation of promoter-associated CpG islands, associated with loss of the H3K4me3 chromatin mark. Far less is known about promoters lacking CpG-islands or genes that are repressed by alternative mechanisms. Methods We performed integrative ChIP-chip, DNase-seq, and global gene expression analyses in colon cancer cells and normal colon mucosa to characterize chromatin features of both CpG-rich and CpG-poor promoters of genes that undergo silencing in colon cancer. Results Epigenetically repressed genes in colon cancer separate into two classes based on retention or loss of H3K4me3 at transcription start sites. Quantitatively, of transcriptionally repressed genes that lose H3K4me3 in colon cancer (K4-dependent genes), a large fraction actually lacks CpG islands. Nonetheless, similar to CpG-island containing genes, cytosines located near the start sites of K4-dependent genes become DNA hypermethylated, and repressed K4-dependent genes can be reactivated with 5-azacytidine. Moreover, we also show that when the H3K4me3 mark is retained, silencing of CpG island-associated genes can proceed through an alternative mechanism in which repressive chromatin marks are recruited. Conclusions H3K4me3 equally protects from DNA methylation at both CpG-island and non-CpG island start sites in colon cancer. Moreover, the results suggest that CpG-rich genes repressed by loss of H3K4me3 and DNA methylation represent special instances of a more general epigenetic mechanism of gene silencing, one in which gene silencing is mediated by loss of H3K4me3 and methylation of non-CpG island promoter-associated cytosines.