Nucleolin is required for DNA methylation state and the expression of rRNA gene variants in Arabidopsis thaliana.
Nucleolin is required for DNA methylation state and the expression of rRNA gene variants in Arabidopsis thaliana.
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DOI：
10.1371/journal.pgen.1001225
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发表时间：
2010-11-24
期刊：
影响因子：
4.5
通讯作者：
Sáez-Vásquez J
中科院分区：
文献类型：
--
作者：
Pontvianne F;Abou-Ellail M;Douet J;Comella P;Matia I;Chandrasekhara C;Debures A;Blevins T;Cooke R;Medina FJ;Tourmente S;Pikaard CS;Sáez-Vásquez J
在真核生物中，45S rRNA 基因串联排列，在植物中拷贝数从数百到数千不等。尽管很明显并非所有拷贝都在正常生长条件下转录，但控制特定 rRNA 基因组表达的分子基础仍不清楚。在这里，我们报告了拟南芥中的四种主要 rRNA 基因变异。有趣的是，在核仁蛋白样蛋白基因（Atnuc-L1）被破坏的拟南芥植物中，虽然这些rRNA变体之一的转录被诱导，但其他变体要么被抑制，要么保持不变。值得注意的是，最具代表性的 rRNA 基因变体在 WT 植物中失活，但在 Atnuc-L1 突变体中重新激活。我们证明积累的 pre-rRNA 源自 RNA Pol I 转录并被准确加工。此外，我们发现 AtNUC-L1 基因的破坏会导致对称 DNA 甲基化的丧失，而不影响 rRNA 基因上的组蛋白表观遗传标记。总的来说，这些数据揭示了 rRNA 基因转录调控的新机制，其中核仁蛋白在控制拟南芥中活性和抑制的 rRNA 基因变异中发挥着主要作用。染色质重塑在所有真核生物的基因表达控制中发挥着核心作用。染色质可以处于抑制或转录不活跃状态（异染色质），也可以处于更宽松或转录活跃状态（常染色质）。染色质的组成部分是核小体，由四种组蛋白 H2A、H2B、H3 和 H4 组成，周围环绕着 147 个 DNA 碱基对。此外，连接组蛋白 H1 引导相邻核小体之间的 DNA 路径，形成染色质纤维。染色质压缩还取决于 DNA 甲基化和许多组蛋白修饰，包括组蛋白尾部的甲基化和乙酰化。然而，需要其他非组蛋白来指导染色质结构和重塑。核仁蛋白是一种主要的核仁蛋白，不仅参与 rRNA 转录和 RNA Pol I 转录的 45S pre-rRNA 的加工，而且还参与核质中 RNA pol II 转录的控制。通过遗传、分子和免疫细胞学方法，我们使用模式植物拟南芥研究了这种蛋白质在体内控制 rRNA 染色质结构和数百个簇状 rRNA 基因表达的作用。
In eukaryotes, 45S rRNA genes are arranged in tandem arrays in copy numbers ranging from several hundred to several thousand in plants. Although it is clear that not all copies are transcribed under normal growth conditions, the molecular basis controlling the expression of specific sets of rRNA genes remains unclear. Here, we report four major rRNA gene variants in Arabidopsis thaliana. Interestingly, while transcription of one of these rRNA variants is induced, the others are either repressed or remain unaltered in A. thaliana plants with a disrupted nucleolin-like protein gene (Atnuc-L1). Remarkably, the most highly represented rRNA gene variant, which is inactive in WT plants, is reactivated in Atnuc-L1 mutants. We show that accumulated pre–rRNAs originate from RNA Pol I transcription and are processed accurately. Moreover, we show that disruption of the AtNUC-L1 gene induces loss of symmetrical DNA methylation without affecting histone epigenetic marks at rRNA genes. Collectively, these data reveal a novel mechanism for rRNA gene transcriptional regulation in which the nucleolin protein plays a major role in controlling active and repressed rRNA gene variants in Arabidopsis. Chromatin remodeling plays a central role in controlling gene expression in all eukaryotic organisms. Chromatin can be found in a repressive or transcriptionally inactive state (heterochromatin) or in a more permissive or transcriptionally active state (euchromatin). The building block of chromatin is the nucleosome, which consists of four histones, H2A, H2B, H3, and H4, surrounded by 147 base pairs of DNA. In addition, a linker histone H1 directs the path of DNA between adjacent nucleosomes to form the chromatin fiber. Chromatin compaction also depends on DNA methylation and on a number of histone modifications, including methylation and acetylation of histone tails. However, other non-histone proteins are required to direct chromatin structure and remodeling. Nucleolin is a major nucleolar protein involved not only in rRNA transcription and processing of 45S pre–rRNA transcribed by RNA Pol I, but also in the control of RNA pol II transcription in the nucleoplasm. Through genetic, molecular, and immunocytological approaches, we studied the role of this protein in vivo in controlling rRNA chromatin structure and the expression of hundreds of clustered rRNA genes using the model plant Arabidopsis thaliana.
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影响因子：
2.9
作者：
KHARRAT, A;DERANCOURT, J;ERARD, M
通讯作者：
ERARD, M
影响因子：
7.2
作者：
Hetzl, Jennifer;Foerster, Andrea M.;Scheid, Ortrun Mittelsten
通讯作者：
Scheid, Ortrun Mittelsten
影响因子：
7.2
作者：
Copenhaver, GP;Pikaard, CS
通讯作者：
Pikaard, CS
DOI：
10.1111/j.1432-1033.1988.tb14224.x
发表时间：
1988-08-15
期刊：
EUROPEAN JOURNAL OF BIOCHEMISTRY
影响因子：
--
作者：
ERARD, MS;BELENGUER, P;AMALRIC, F
通讯作者：
AMALRIC, F
影响因子：
4.5
作者：
Kufel, J;Dichtl, B;Tollervey, D
通讯作者：
Tollervey, D