Chromatin reorganization accompanying cellular dedifferentiation is associated with modifications of histone H3, redistribution of HP1, and activation of E2F‐target genes
Chromatin reorganization accompanying cellular dedifferentiation is associated with modifications of histone H3, redistribution of HP1, and activation of E2F‐target genes
复制标题
DOI：
10.1002/dvdy.10348
复制
发表时间：
2003-09
影响因子：
2.5
通讯作者：
L. Williams;Jing Zhao-;N. Morozova;Yan Li;Y. Avivi;G. Grafi
中科院分区：
文献类型：
--
作者：
L. Williams;Jing Zhao-;N. Morozova;Yan Li;Y. Avivi;G. Grafi
植物细胞显著的再生能力是基于它们的去分化能力。我们最近报道了细胞去分化通过两个不同的阶段进行，每个阶段都伴随着染色质去凝聚：获得命运转换的能力，然后信号依赖性地重新进入S期（Zhao et al. [ 2001 ] J. Biol. Chem. 276：22772 - 22778）。本研究的目的是（1）表征与染色质去浓缩相关的染色质因子的变化，以及（2）研究染色质去浓缩与pRb/E2 F调控基因的转录激活之间的关系。我们发现，植物细胞主管命运开关显示中断核仁结构域外观与18 S核糖体DNA的缩合，以及组蛋白H3和异染色质蛋白1（HP 1）的重新分配的修改。我们进一步表明，pRb/E2 F-靶基因RNR 2和PCNA在分化的叶细胞中是浓缩和沉默的，但随着细胞获得命运开关的能力，尽管尚未激活，但变得去浓缩;转录激活在进入S期的过程中变得明显，伴随着pRb磷酸化。我们认为，染色质重组是逆转分化过程的核心，导致基因表达程序的重置和沉默基因的激活。Developmental Dynamics 228：113-120，2003.© 2003 Wiley利斯公司
The remarkable regeneration capacity of plant cells is based on their capability to dedifferentiate. We recently reported that cellular dedifferentiation proceeds through two distinct phases, each accompanied by chromatin decondensation: acquisition of competence for fate switch followed by a signal‐dependent reentry into S phase (Zhao et al. [ 2001 ] J. Biol. Chem. 276:22772‐22778). The purpose of this study was to (1) characterize changes in chromatin factors associated with chromatin decondensation, and (2) study the relationship between chromatin decondensation and transcriptional activation of pRb/E2F‐regulated genes. We show that plant cells competent for fate switch display a disruption of nucleolar domain appearance associated with condensation of 18S ribosomal DNA, as well as modifications of histone H3 and redistribution of heterochromatin protein 1 (HP1). We further show that the pRb/E2F‐target genes RNR2 and PCNA are condensed and silent in differentiated leaf cells but become decondensed, although not yet activated, as cells acquire competence for fate switch; transcriptional activation becomes evident during progression into S phase, concomitantly with pRb phosphorylation. We propose that chromatin reorganization is central for reversion of the differentiation process leading to resetting of the gene expression program and activation of silent genes. Developmental Dynamics 228:113–120, 2003. © 2003 Wiley‐Liss, Inc.