Whitehead Institute for Biomedical Research, Cambridge, United States.
Department of Biology, Massachusetts Institute of Technology, Cambridge, United States.
Elife. 2020 Nov 11;9:e59770. doi: 10.7554/eLife.59770.
Although originally thought to be silent chromosomal regions, centromeres are instead actively transcribed. However, the behavior and contributions of centromere-derived RNAs have remained unclear. Here, we used single-molecule fluorescence in-situ hybridization (smFISH) to detect alpha-satellite RNA transcripts in intact human cells. We find that alpha-satellite RNA-smFISH foci levels vary across cell lines and over the cell cycle, but do not remain associated with centromeres, displaying localization consistent with other long non-coding RNAs. Alpha-satellite expression occurs through RNA polymerase II-dependent transcription, but does not require established centromere or cell division components. Instead, our work implicates centromere-nucleolar interactions as repressing alpha-satellite expression. The fraction of nucleolar-localized centromeres inversely correlates with alpha-satellite transcripts levels across cell lines and transcript levels increase substantially when the nucleolus is disrupted. The control of alpha-satellite transcripts by centromere-nucleolar contacts provides a mechanism to modulate centromere transcription and chromatin dynamics across diverse cell states and conditions.
虽然最初被认为是沉默的染色体区域，但着丝粒实际上是活跃转录的。然而，着丝粒衍生 RNA 的行为和贡献仍然不清楚。在这里，我们使用单分子荧光原位杂交 (smFISH) 在完整的人类细胞中检测α-卫星 RNA 转录本。我们发现，α-卫星 RNA-smFISH 焦点水平在细胞系和细胞周期中都有所不同，但不与着丝粒保持关联，其定位与其他长非编码 RNA 一致。α-卫星表达通过 RNA 聚合酶 II 依赖性转录发生，但不依赖于已建立的着丝粒或细胞分裂成分。相反，我们的工作表明着丝粒-核仁相互作用抑制α-卫星的表达。核仁定位的着丝粒与不同细胞系中的α-卫星转录本水平呈负相关，并且当核仁被破坏时，转录本水平会大幅增加。通过着丝粒-核仁接触对α-卫星转录本的控制提供了一种机制，可以调节不同细胞状态和条件下的着丝粒转录和染色质动态。
