Postembryonic establishment of megabase-scale gene silencing in nucleolar dominance.
Postembryonic establishment of megabase-scale gene silencing in nucleolar dominance.
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DOI：
10.1371/journal.pone.0001157
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发表时间：
2007-11-07
期刊：
影响因子：
3.7
通讯作者：
Pikaard CS
中科院分区：
文献类型：
--
作者：
Pontes O;Lawrence RJ;Silva M;Preuss S;Costa-Nunes P;Earley K;Neves N;Viegas W;Pikaard CS
核仁显性是动植物遗传杂种中的一种表观遗传现象，描述了由于另一个祖先的rRNA基因的沉默而从一个祖先遗传的45 S核糖体RNA基因（rRNA基因）的表达。rRNA基因串联排列在跨越数百万个碱基对的核仁组织者区（NOR），因此核仁优势中的基因沉默在雌性哺乳动物中的发生规模仅次于X染色体失活。在拟南芥（Arabidopsis suecica）中，A.和拟南芥A. arenosa，A.来源于拟南芥的rRNA基因受到核仁优势的支配，并通过抑制性染色质修饰而沉默。然而，核仁优势的发育阶段在A。苏西卡目前下落不明。我们发现，核仁的优势是不明显的胚胎发生过程中形成的幼苗子叶，但逐渐建立在早期胚后发育的组织中来自芽和根的顶端分生组织。A. thaliana rRNA基因与A.拟南芥的NORs从与组蛋白H3相关的去致密常染色质状态（其在赖氨酸4（H3 K4 me 3）上被三甲基化）到高度浓缩的异染色质状态（其中NORs与H3 K9 me 2和5-甲基胞嘧啶富集的色中心相关）。在组蛋白去乙酰化酶HDA 6和HDT 1被敲低的RNAi系中，发育调节的A. Thaliana NORs被破坏。总的来说，这些数据表明，HDA 6和HDT 1功能在核仁优势，在每一代复发的过程中胚后建立。
Nucleolar dominance is an epigenetic phenomenon in plant and animal genetic hybrids that describes the expression of 45S ribosomal RNA genes (rRNA genes) inherited from only one progenitor due to the silencing of the other progenitor's rRNA genes. rRNA genes are tandemly arrayed at nucleolus organizer regions (NORs) that span millions of basepairs, thus gene silencing in nucleolar dominance occurs on a scale second only to X-chromosome inactivation in female mammals. In Arabidopsis suecica, the allotetraploid hybrid of A. thaliana and A. arenosa, the A. thaliana –derived rRNA genes are subjected to nucleolar dominance and are silenced via repressive chromatin modifications. However, the developmental stage at which nucleolar dominance is established in A. suecica is currently unknown. We show that nucleolar dominance is not apparent in seedling cotyledons formed during embryogenesis but becomes progressively established during early postembryonic development in tissues derived from both the shoot and root apical meristems. The progressive silencing of A. thaliana rRNA genes correlates with the transition of A. thaliana NORs from a decondensed euchromatic state associated with histone H3 that is trimethylated on lysine 4 (H3K4me3) to a highly condensed heterochromatic state in which the NORs are associated with H3K9me2 and 5-methylcytosine-enriched chromocenters. In RNAi-lines in which the histone deacetylases HDA6 and HDT1 are knocked down, the developmentally regulated condensation and inactivation of A. thaliana NORs is disrupted. Collectively, these data demonstrate that HDA6 and HDT1 function in the postembryonic establishment of nucleolar dominance, a process which recurs in each generation.
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DOI：
10.1002/9780470988626.ch7
发表时间：
2005-01-01
期刊：
PLANT EPIGENETICS
影响因子：
--
作者：
Neves, Nuno;Viegas, Wanda;Pikaard, Craig S.
通讯作者：
Pikaard, Craig S.
影响因子：
5.4
作者：
NEVES, N;HESLOPHARRISON, JS;VIEGAS, W
通讯作者：
VIEGAS, W
影响因子：
64.5
作者：
Goldberg, Aaron D.;Allis, C. David;Bernstein, Emily
通讯作者：
Bernstein, Emily
影响因子：
16
作者：
Lawrence, RJ;Earley, K;Pikaard, CS
通讯作者：
Pikaard, CS
影响因子：
1
作者：
NAVASHIN, M.
通讯作者：
NAVASHIN, M.