Institute of Plant Biology, National Taiwan University, Taipei 106, Taiwan.
Plant Physiol. 2012 Jan;158(1):119-29. doi: 10.1104/pp.111.184275. Epub 2011 Oct 12.
The molecular mechanism of how the histone deacetylase HDA6 participates in maintaining transposable element (TE) silencing in Arabidopsis (Arabidopsis thaliana) is not yet defined. In this study, we show that a subset of TEs was transcriptionally reactivated and that TE reactivation was associated with elevated histone H3 and H4 acetylation as well as increased H3K4Me3 and H3K4Me2 in hda6 mutants. Decreased DNA methylation of the TEs was also detected in hda6 mutants, suggesting that HDA6 silences the TEs by regulating histone acetylation and methylation as well as the DNA methylation status of the TEs. Similarly, transcripts of some of these TEs were also increased in the methyltransferase1 (met1) mutant, with decreased DNA methylation. Furthermore, H4 acetylation, H3K4Me3, H3K4Me2, and H3K36Me2 were enriched at the coregulated TEs in the met1 and hda6 met1 mutants. Protein-protein interaction analysis indicated that HDA6 physically interacts with MET1 in vitro and in vivo, and further deletion analysis demonstrated that the carboxyl-terminal region of HDA6 and the bromo-adjacent homology domain of MET1 were responsible for the interaction. These results suggested that HDA6 and MET1 interact directly and act together to silence TEs by modulating DNA methylation, histone acetylation, and histone methylation status.
组蛋白去乙酰化酶 HDA6 参与维持拟南芥转座元件 (TE) 沉默的分子机制尚不清楚。在这项研究中，我们表明一组 TEs 被转录重新激活，并且 TE 的重新激活与组蛋白 H3 和 H4 的乙酰化以及 H3K4Me3 和 H3K4Me2 的增加有关在 hda6 突变体中。在 hda6 突变体中还检测到 TE 的 DNA 甲基化减少，表明 HDA6 通过调节组蛋白乙酰化和甲基化以及 TE 的 DNA 甲基化状态来沉默 TE。类似地，在甲基转移酶 1 (met1) 突变体中，一些这些 TE 的转录本也增加了，DNA 甲基化减少。此外，在 met1 和 hda6 met1 突变体中，H4 乙酰化、H3K4Me3、H3K4Me2 和 H3K36Me2 在共调控的 TE 上富集。蛋白质-蛋白质相互作用分析表明 HDA6 在体外和体内与 MET1 物理相互作用，进一步的缺失分析表明 HDA6 的羧基末端区域和 MET1 的溴邻域同源结构域负责相互作用。这些结果表明 HDA6 和 MET1 直接相互作用，并通过调节 DNA 甲基化、组蛋白乙酰化和组蛋白甲基化状态共同作用来沉默 TE。
