Biology Department, Washington University, St. Louis, MO, USA.
Nucleus. 2010 May-Jun;1(3):254-9. doi: 10.4161/nucl.1.3.11741. Epub 2010 Mar 2.
Nucleolar dominance is a widespread epigenetic phenomenon, describing the preferential silencing of ribosomal RNA (rRNA) genes inherited from one progenitor of an interspecific hybrid, independent of maternal or paternal effects. In the allotetraploid hybrid plant species Arabidopsis suecica, A. thaliana-derived rRNA genes are silenced whereas the A. arenosa-derived rRNA genes are transcribed. We reported previously on an RNAi-based screen of DNA methyltransferases, methylcytosine binding proteins and RNA-dependent DNA methylation pathway proteins that identified specific activities required for the establishment or enforcement of nucleolar dominance. Here we present additional molecular and cell biological evidence that siRNA-directed cytosine methylation and the methylcytosine binding protein MBD6 bring about large-scale chromosomal effects on rRNA gene loci subjected to nucleolar dominance in A. suecica.
核仁优势是一种广泛存在的表观遗传现象，描述了来自种间杂种一个亲本的核糖体 RNA（rRNA）基因的优先沉默，这种沉默独立于母本或父本效应。在拟南芥的异源四倍体杂种植物种中，A. thaliana 衍生的 rRNA 基因被沉默，而 A. arenosa 衍生的 rRNA 基因则被转录。我们之前报道了一个基于 RNAi 的 DNA 甲基转移酶、甲基胞嘧啶结合蛋白和 RNA 依赖的 DNA 甲基化途径蛋白的筛选，该筛选鉴定了建立或执行核仁优势所需的特定活性。在这里，我们提供了额外的分子和细胞生物学证据，表明 siRNA 指导的胞嘧啶甲基化和甲基胞嘧啶结合蛋白 MBD6 导致拟南芥中核仁优势的 rRNA 基因座上发生大规模的染色体效应。
