Compacted, transcriptionally repressed chromatin, referred to as heterochromatin, represents a major fraction of the higher eukaryotic genome and exerts pivotal functions of silencing repetitive elements, maintenance of genome stability, and control of gene expression. Among the different histone post-translational modifications (PTMs) associated with heterochromatin, tri-methylation of lysine 9 on histone H3 (H3K9me3) is gaining increased attention. Besides its known role in repressing repetitive elements and non-coding portions of the genome, recent observations indicate H3K9me3 as an important player in silencing lineage-inappropriate genes. The ability of H3K9me3 to influence cell identity challenges the original concept of H3K9me3-marked heterochromatin as mainly a constitutive type of chromatin and provides a further level of understanding of how to modulate cell fate control. Here, we summarize the role of H3K9me3 marked heterochromatin and its dynamics in establishing and maintaining cellular identity.

中文翻译：

---

H3K9me3异染色质在细胞身份建立和维持中的作用。

紧密的，转录抑制的染色质，称为异染色质，代表了高等真核生物基因组的主要部分，并发挥了沉默重复元件，维持基因组稳定性和控制基因表达的关键功能。在与异染色质相关的不同组蛋白翻译后修饰（PTM）中，组蛋白H3（H3K9me3）上赖氨酸9的三甲基化受到越来越多的关注。除了其在抑制基因组的重复元件和非编码部分方面的已知作用外，最近的观察结果表明，H3K9me3是沉默不适合谱系基因的重要参与者。H3K9me3影响细胞身份的能力挑战了H3K9me3标记的异染色质（主要是染色质的组成型）的原始概念，并提供了如何调节细胞命运控制的进一步理解。在这里，我们总结了H3K9me3标记的异染色质的作用及其在建立和维持细胞身份方面的动态。