Department of Biology, ETH Zürich, Zürich, Switzerland.
Howard Hughes Medical Institute, Chevy Chase, MD, USA.
Mol Biol Evol. 2021 Oct 27;38(11):4977-4986. doi: 10.1093/molbev/msab221.
Although rapid evolution of pericentromeric satellite DNA repeats is theorized to promote hybrid incompatibility (HI) (Yunis and Yasmineh 1971; Henikoff et al. 2001; Ferree and Barbash 2009; Sawamura 2012; Jagannathan and Yamashita 2017), how divergent repeats affect hybrid cells remains poorly understood. Recently, we demonstrated that sequence-specific DNA-binding proteins cluster satellite DNA from multiple chromosomes into "chromocenters," thereby bundling chromosomes to maintain the entire genome in a single nucleus (Jagannathan et al. 2018, 2019). Here, we show that ineffective clustering of divergent satellite DNA in the cells of Drosophila hybrids results in chromocenter disruption, associated micronuclei formation, and tissue atrophy. We further demonstrate that previously identified HI factors trigger chromocenter disruption and micronuclei in hybrids, linking their function to a conserved cellular process. Together, we propose a unifying framework that explains how the widely observed satellite DNA divergence between closely related species can cause reproductive isolation.
虽然理论上认为着丝粒卫星 DNA 重复序列的快速进化会促进杂种不亲和性（HI）（Yunis 和 Yasmineh 1971；Henikoff 等人，2001；Ferree 和 Barbash，2009；Sawamura，2012；Jagannathan 和 Yamashita，2017），但重复序列的差异如何影响杂种细胞仍知之甚少。最近，我们证明了序列特异性 DNA 结合蛋白将来自多个染色体的卫星 DNA 聚集到“染色中心”中，从而将染色体捆绑在一起，使整个基因组在单个核中保持稳定（Jagannathan 等人，2018，2019）。在这里，我们表明，在果蝇杂种细胞中，发散的卫星 DNA 无效聚类导致染色中心解体，伴随微核形成和组织萎缩。我们进一步证明，先前鉴定的 HI 因子在杂种中触发染色中心解体和微核形成，将其功能与保守的细胞过程联系起来。综上所述，我们提出了一个统一的框架，解释了为什么在密切相关的物种之间广泛观察到的卫星 DNA 分歧会导致生殖隔离。
