Department of Biochemistry, University of Oxford, Oxford, UK.
Instituto Gulbenkian de Ciência, Oeiras, Portugal.
J Cell Biol. 2021 Mar 1;220(3). doi: 10.1083/jcb.202007210.
Human centromeres form primarily on α-satellite DNA but sporadically arise de novo at naive ectopic loci, creating neocentromeres. Centromere inheritance is driven primarily by chromatin containing the histone H3 variant CENP-A. Here, we report a chromosome engineering system for neocentromere formation in human cells and characterize the first experimentally induced human neocentromere at a naive locus. The spontaneously formed neocentromere spans a gene-poor 100-kb domain enriched in histone H3 lysine 9 trimethylated (H3K9me3). Long-read sequencing revealed this neocentromere was formed by purely epigenetic means and assembly of a functional kinetochore correlated with CENP-A seeding, eviction of H3K9me3 and local accumulation of mitotic cohesin and RNA polymerase II. At formation, the young neocentromere showed markedly reduced chromosomal passenger complex (CPC) occupancy and poor sister chromatin cohesion. However, long-term tracking revealed increased CPC assembly and low-level transcription providing evidence for centromere maturation over time.
人类着丝粒主要形成于α-卫星 DNA 上，但偶尔也会在原始异位位置从头出现，形成新着丝粒。着丝粒的遗传主要由含有组蛋白 H3 变体 CENP-A 的染色质驱动。在这里，我们报告了一种在人类细胞中形成新着丝粒的染色体工程系统，并在原始位置表征了第一个实验诱导的人类新着丝粒。自发形成的新着丝粒跨越富含组蛋白 H3 赖氨酸 9 三甲基化（H3K9me3）的基因贫乏 100kb 区域。长读测序显示，这个新着丝粒是通过纯粹的表观遗传手段形成的，并且组装一个功能的动粒与 CENP-A 播种、H3K9me3 的驱逐以及有丝分裂黏合蛋白和 RNA 聚合酶 II 的局部积累有关。在形成过程中，年轻的新着丝粒显示出明显减少的染色体乘客复合物（CPC）占有率和较差的姐妹染色质凝聚。然而，长期跟踪显示 CPC 组装增加和低水平转录，为随着时间的推移着丝粒成熟提供了证据。
