Berry Scott, Hartley Matthew, Olsson Tjelvar S G, Dean Caroline, Howard Martin
John Innes Centre, Norwich, United Kingdom.
Elife. 2015 May 8;4:e07205. doi: 10.7554/eLife.07205.
Inheritance of gene expression states is fundamental for cells to 'remember' past events, such as environmental or developmental cues. The conserved Polycomb Repressive Complex 2 (PRC2) maintains epigenetic repression of many genes in animals and plants and modifies chromatin at its targets. Histones modified by PRC2 can be inherited through cell division. However, it remains unclear whether this inheritance can direct long-term memory of individual gene expression states (cis memory) or instead if local chromatin states are dictated by the concentrations of diffusible factors (trans memory). By monitoring the expression of two copies of the Arabidopsis Polycomb target gene FLOWERING LOCUS C (FLC) in the same plants, we show that one copy can be repressed while the other is active. Furthermore, this 'mixed' expression state is inherited through many cell divisions as plants develop. These data demonstrate that epigenetic memory of FLC expression is stored not in trans but in cis.
基因表达状态的遗传对于细胞“记住”过去的事件（如环境或发育线索）至关重要。保守的多梳抑制复合物2（PRC2）维持动物和植物中许多基因的表观遗传抑制，并在其靶标处修饰染色质。经PRC2修饰的组蛋白可通过细胞分裂遗传。然而，目前尚不清楚这种遗传是能否指导单个基因表达状态的长期记忆（顺式记忆），还是局部染色质状态由可扩散因子的浓度决定（反式记忆）。通过监测同一植物中拟南芥多梳靶基因开花位点C（FLC）的两个拷贝的表达，我们发现一个拷贝可以被抑制而另一个拷贝是活跃的。此外，随着植物的发育，这种“混合”表达状态通过许多细胞分裂遗传。这些数据表明，FLC表达的表观遗传记忆不是以反式而是以顺式存储的。
