拟南芥中表观遗传遗传的两步过程。
A two-step process for epigenetic inheritance in Arabidopsis.
机构信息
Howard Hughes Medical Institute, Indiana University, Bloomington, IN 47405, USA; Department of Biology and Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA.
Department of Biology and Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA.
出版信息
Mol Cell. 2014 Apr 10;54(1):30-42. doi: 10.1016/j.molcel.2014.02.019. Epub 2014 Mar 20.
In Arabidopsis, multisubunit RNA polymerases IV and V orchestrate RNA-directed DNA methylation (RdDM) and transcriptional silencing, but what identifies the loci to be silenced is unclear. We show that heritable silent locus identity at a specific subset of RdDM targets requires HISTONE DEACETYLASE 6 (HDA6) acting upstream of Pol IV recruitment and siRNA biogenesis. At these loci, epigenetic memory conferring silent locus identity is erased in hda6 mutants such that restoration of HDA6 activity cannot restore siRNA biogenesis or silencing. Silent locus identity is similarly lost in mutants for the cytosine maintenance methyltransferase, MET1. By contrast, pol IV or pol V mutants disrupt silencing without erasing silent locus identity, allowing restoration of Pol IV or Pol V function to restore silencing. Collectively, these observations indicate that silent locus specification and silencing are separable steps that together account for epigenetic inheritance of the silenced state.
在拟南芥中，多亚基 RNA 聚合酶 IV 和 V 协调 RNA 指导的 DNA 甲基化（RdDM）和转录沉默，但哪些基因座需要沉默尚不清楚。我们发现，在特定的 RdDM 靶标子集上，可遗传的沉默基因座特征需要组蛋白去乙酰化酶 6（HDA6）在上游作用于 Pol IV 的募集和 siRNA 生物发生。在这些基因座上，赋予沉默基因座特征的表观遗传记忆在 hda6 突变体中被抹去，以至于恢复 HDA6 活性不能恢复 siRNA 的生物发生或沉默。在胞嘧啶维持甲基转移酶 MET1 的突变体中，沉默基因座特征也会丢失。相比之下，pol IV 或 pol V 突变体破坏沉默而不抹去沉默基因座特征，允许恢复 Pol IV 或 Pol V 功能来恢复沉默。总的来说，这些观察结果表明，沉默基因座的指定和沉默是可分离的步骤，共同解释了沉默状态的表观遗传遗传。
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