Reorganization of specific chromosomal domains and activation of silent genes in plant cells acquiring pluripotentiality

Divide and conquer: development and cell cycle genes in plant transformation

“…In addition, monitoring of S-phase-specific genes, such as RNR, MCM, CDC6, PCNA, H2A, H4 and E2Fa [23][24][25]38], might give detailed insights into the mechanisms of cell cycle modulation: using microarray analysis, O100 genes related to S phase have been identified in Arabidopsis after overexpression of E2Fa-DPa [24]. In addition, changes in heterochromatin remodeling, DNA or histone methylation and histone acetylation and deacetylation can be directly monitored by a variety of methods [17][18][19]60]. With the diversity of genomic databases, regeneration systems and developmental obstacles in various species, we anticipate a rich variety of approaches and successes in upcoming years.…”

“…In addition, methylated histone tails attract heterochromatin protein 1 (HP1), which causes further compaction of the DNA or the formation of heterochromatin [16]. Transcriptionally active genes are associated with euchromatic areas, whereas heterochromatin contains mostly transcriptionally inactive genes [17,18]. However, even within euchromatic regions, condensed areas of heterochromatin are common.…”

“…Both of these steps involve chromatin remodeling [7], although the G0-G1 transition involves chromatin relaxation rather than DNA synthesis [19]. In general, the competence of a cell to switch fate or acquire pluripotentiality [7] is accompanied by posttranslational modifications of histone H3, redistribution of heterochromatin protein 1 (HP1), changes in DNAmethylation patterns and activation of silent genes such as VIP1 and no apical meristem (NAM)-like genes [17].…”

“…VIP1 (VirE2 interacting protein 1) is a gene present in Arabidopsis; it is normally silent in differentiated cells but was up-regulated during the acquisition of pluripotentiality [17]. Further research determined that VIP1 interacts with VirE2 from Agrobacterium and with several histones, facilitating the integration of the foreign DNA into the plant genome [33,34].…”

Impact of nucleosome dynamics and histone modifications on cell proliferation during Arabidopsis development

“…During the dedifferentiation process, redistribution of LHP1, disruption of the nucleolus and posttranslational modifications of histone H3 can be evidenced (Williams et al, 2003). The DNA methylation and H3K9me2 patterns, that mark heterochromatin, are not globally altered (Tessadori et al, 2007), but there is a specific reorganization of chromosomal subdomains with reduced DNA methylation that leads to the activation of silent genes (Avivi et al, 2004;Koukalova et al, 2005). The histone methyltransferase mutant kryptonite (kyp/suvh4), with reduced H3K9me2, fails to form calli structures, suggesting a role of H3K9 methylation in the dedifferentiation and/or proliferation stages (Figure 1).…”