The precise regulation of gene transcription is required to establish and maintain cell type-specific gene expression programs during multicellular development. In addition to transcription factors, chromatin, and its chemical modification, play a central role in regulating gene expression. In vertebrates, DNA is pervasively methylated at CG dinucleotides, a modification that is repressive to transcription. However, approximately 70% of vertebrate gene promoters are associated with DNA elements called CpG islands (CGIs) that are refractory to DNA methylation. CGIs integrate the activity of a range of chromatin-regulating factors that can post-translationally modify histones and modulate gene expression. This is exemplified by the trimethylation of histone H3 at lysine 4 (H3K4me3), which is enriched at CGI-associated gene promoters and correlates with transcriptional activity. Through studying H3K4me3 at CGIs it has become clear that CGIs shape the distribution of H3K4me3 and, in turn, H3K4me3 influences the chromatin landscape at CGIs. Here we will discuss our understanding of the emerging relationship between CGIs, H3K4me3, and gene expression.

中文翻译：

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了解CpG岛相关的基因启动子和H3K4甲基化之间的相互作用。

要在多细胞发育过程中建立和维持特定于细胞类型的基因表达程序，就需要精确调控基因转录。除转录因子外，染色质及其化学修饰在调节基因表达中起着核心作用。在脊椎动物中，DNA在CG二核苷酸处普遍被甲基化，这种修饰可抑制转录。但是，大约70％的脊椎动物基因启动子与对DNA甲基化具有抵抗力的称为CpG岛（CGI）的DNA元件相关。CGI整合了一系列染色质调节因子的活性，这些因子可以翻译后修饰组蛋白并调节基因表达。这可以通过组氨酸H3在赖氨酸4（H3K4me3）处的三甲基化来举例说明，它在CGI相关基因启动子处富集，并与转录活性相关。通过在CGI处研究H3K4me3，已经清楚地发现CGI会影响H3K4me3的分布，进而影响H3K4me3在CGI处的染色质分布。在这里，我们将讨论对CGI，H3K4me3和基因表达之间新兴关系的理解。