GSE122683
A microRNA-inducible CRISPR-Cas9 platform serves as microRNA sensors and cell type specific genome regulation tools
microRNAs (miRNAs) are an important class of small regulatory noncoding RNAs expressed by plants, animals and viruses. However, measuring miRNA activity in vivo remains a big challenge. Using a miRNA-mediated sgRNA releasing strategy and dCas9-VPR to drive a transgene RFP expression, we create a miRNA sensor that can faithfully measure miRNA activity at cellular levels and show that it can be used to monitor the differentiation status of stem cells. When sgRNAs are designed to target endogenous locus, we show this system can be adopted to achieve cell type specific activation of endogenous genes. Furthermore, when dCas9 is fused with a transcriptional repressor or a base editor, we show this system can be used to repress the expression of endogenous genes or mutate specific DNA bases of chromosome depending on the expression of cell type-specific miRNAs. Finally, by a miRNA sensor library screening, we discovered a previously undefined layer of heterogeneity associated with miR-21a activity in mouse embryonic stem cells. Together, these results highlight the utility of a miRNA-induced CRISPR-Cas9 system as miRNA sensors and cell type-specific genome regulation tools. Overall design: Examination of differential expressed genes between sorted RFP low and RFP high mouse embryonic stem cells by poly(A)+ RNA-Seq. Two independently prepared mouse ESCs samples were used for RNA-seq.