Spatial organization of the genome in the nucleus plays a critical role in development and regulation of transcription. A genomic region that resides at the nuclear periphery is part of the chromatin layer marked with histone H3 lysine 9 dimethyl (H3K9me2), but chromatin reorganization during cell differentiation can cause movement in and out of this nuclear compartment with patterns specific for individual cell fates. Here we describe a CRISPR-based system that allows visualization coupled with forced spatial relocalization of a target genomic locus in live cells. We demonstrate that a specified locus can be tethered to the nuclear periphery through direct binding to a dCas9-Lap2β fusion protein at the nuclear membrane, or via targeting of a histone methyltransferase (HMT), G9a fused to dCas9, that promotes H3K9me2 labeling and localization to the nuclear periphery. The enzymatic activity of the HMT is sufficient to promote this repositioning, while disruption of the catalytic activity abolishes the localization effect. We further demonstrate that dCas9-G9a-mediated localization to the nuclear periphery is independent of nuclear actin polymerization. Our data suggest a function for epigenetic histone modifying enzymes in spatial chromatin organization and provide a system for tracking and labeling targeted genomic regions in live cells.

细胞核中基因组的空间组织在转录的发展和调节中起着关键作用。位于核外围的基因组区域是染色质层的一部分，标记有组蛋白 H3 赖氨酸 9 二甲基 (H3K9me2)，但细胞分化过程中的染色质重组会导致进出该核区室，并具有特定于单个细胞命运的模式。在这里，我们描述了一个基于 CRISPR 的系统，该系统允许可视化与活细胞中目标基因组位点的强制空间重新定位相结合。我们证明可以通过直接结合核膜上的 dCas9-Lap2β 融合蛋白，或通过靶向组蛋白甲基转移酶 (HMT)，G9a 与 dCas9 融合，将特定基因座连接到核外围，促进 H3K9me2 标记和定位到核外围。HMT 的酶活性足以促进这种重新定位，而催化活性的破坏则消除了定位效应。我们进一步证明 dCas9-G9a 介导的核外围定位与核肌动蛋白聚合无关。我们的数据表明空间染色质组织中表观遗传组蛋白修饰酶的功能，并提供了一个系统来跟踪和标记活细胞中的目标基因组区域。我们进一步证明 dCas9-G9a 介导的核外围定位与核肌动蛋白聚合无关。我们的数据表明空间染色质组织中表观遗传组蛋白修饰酶的功能，并提供了一个系统来跟踪和标记活细胞中的目标基因组区域。我们进一步证明 dCas9-G9a 介导的核外围定位与核肌动蛋白聚合无关。我们的数据表明空间染色质组织中表观遗传组蛋白修饰酶的功能，并提供了一个系统来跟踪和标记活细胞中的目标基因组区域。