CRISPR-Cas9 technologies have dramatically increased the ease of targeting DNA sequences in the genomes of living systems. The fusion of chromatin-modifying domains to nuclease-deactivated Cas9 (dCas9) has enabled targeted epigenome editing in both cultured cells and animal models. However, delivering large dCas9 fusion proteins to target cells and tissues is an obstacle to the widespread adoption of these tools for in vivo studies. Here, we describe the generation and characterization of two conditional transgenic mouse lines for epigenome editing, Rosa26:LSL-dCas9-p300 for gene activation and Rosa26:LSL-dCas9-KRAB for gene repression. By targeting the guide RNAs to transcriptional start sites or distal enhancer elements, we demonstrate regulation of target genes and corresponding changes to epigenetic states and downstream phenotypes in the brain and liver in vivo, and in T cells and fibroblasts ex vivo. These mouse lines are convenient and valuable tools for facile, temporally controlled, and tissue-restricted epigenome editing and manipulation of gene expression in vivo.

CRISPR-Cas9 技术极大地提高了靶向生命系统基因组中 DNA 序列的容易性。染色质修饰域与核酸酶失活 Cas9 (dCas9) 的融合使得在培养细胞和动物模型中进行靶向表观基因组编辑成为可能。然而，将大的 dCas9 融合蛋白递送到靶细胞和组织是这些工具广泛应用于体内研究的障碍。在这里，我们描述了用于表观基因组编辑的两种条件转基因小鼠品系的生成和表征，即用于基因激活的 Rosa26:LSL-dCas9-p300 和用于基因抑制的 Rosa26:LSL-dCas9-KRAB。通过将引导RNA靶向转录起始位点或远端增强子元件，我们证明了体内大脑和肝脏以及离体T细胞和成纤维细胞中靶基因的调节以及表观遗传状态和下游表型的相应变化。这些小鼠品系是方便且有价值的工具，可用于轻松、时间控制和组织限制的表观基因组编辑和体内基因表达操作。