Institut de Génétique Humaine, CNRS UPR 1142, Montpellier, France.
Cell. 2011 Jan 21;144(2):214-26. doi: 10.1016/j.cell.2010.12.026.
In Drosophila melanogaster, Hox genes are organized in an anterior and a posterior cluster, called Antennapedia complex and bithorax complex, located on the same chromosome arm and separated by 10 Mb of DNA. Both clusters are repressed by Polycomb group (PcG) proteins. Here, we show that genes of the two Hox complexes can interact within nuclear PcG bodies in tissues where they are corepressed. This colocalization increases during development and depends on PcG proteins. Hox gene contacts are conserved in the distantly related Drosophila virilis species and they are part of a large gene interaction network that includes other PcG target genes. Importantly, mutations on one of the loci weaken silencing of genes in the other locus, resulting in the exacerbation of homeotic phenotypes in sensitized genetic backgrounds. Thus, the three-dimensional organization of Polycomb target genes in the cell nucleus stabilizes the maintenance of epigenetic gene silencing.
在黑腹果蝇中，Hox 基因被组织在一个称为触角足复合体（Antennapedia complex）和双胸复合体（bithorax complex）的前簇和后簇中，位于同一染色体臂上，由 10Mb 的 DNA 隔开。这两个簇都被 Polycomb 组（PcG）蛋白抑制。在这里，我们表明，两个 Hox 复合物中的基因可以在它们被核心抑制的组织中的核 PcG 体中相互作用。这种共定位在发育过程中增加，并依赖于 PcG 蛋白。Hox 基因的接触在亲缘关系较远的果蝇 virilis 物种中是保守的，它们是一个包括其他 PcG 靶基因的大基因相互作用网络的一部分。重要的是，一个基因座上的突变削弱了另一个基因座上基因的沉默，导致在敏感遗传背景下同异位表型的加剧。因此，细胞内 PcG 靶基因的三维组织稳定了表观遗传基因沉默的维持。
