Faivre Léa, Schubert Daniel
Epigenetics of Plants, Freie Universität Berlin, Berlin, Germany.
J Exp Bot. 2023 Mar 28;74(6):1770-1783. doi: 10.1093/jxb/erad029.
Chromatin is an essential contributor to the regulation of transcription. The two histone post-translational modifications H3K4me3 and H3K27me3 act as an activator and repressor of gene expression, respectively, and are usually described as being mutually exclusive. However, recent work revealed that both marks might co-exist at several loci, forming a distinctive chromatin state called bivalency. While this state has been detected on a handful of genes involved in plant development and stress responses, its role in the regulation of transcription remains unclear. In an effort to shed more light on the putative function(s) of bivalency in plants, this review details the potential players involved in its setting and reading, and explores how this chromatin state might contribute to the control of gene expression. We propose that bivalency maintains transcriptional plasticity by facilitating transitions between a repressed and an active state and/or by preventing irreversible silencing of its targets. We also highlight recently developed techniques that could be used for further investigating bivalency.
染色质是转录调控的重要贡献者。两种组蛋白翻译后修饰H3K4me3和H3K27me3分别作为基因表达的激活剂和抑制剂，通常被描述为相互排斥。然而，最近的研究表明，这两种标记可能在几个位点共存，形成一种独特的染色质状态，称为双价性。虽然这种状态已在少数参与植物发育和应激反应的基因上被检测到，但其在转录调控中的作用仍不清楚。为了更深入地了解双价性在植物中的假定功能，本综述详细介绍了参与其形成和识别的潜在因素，并探讨了这种染色质状态如何有助于基因表达的控制。我们提出，双价性通过促进抑制状态和激活状态之间的转换和/或通过防止其靶标的不可逆沉默来维持转录可塑性。我们还强调了最近开发的可用于进一步研究双价性的技术。
