biostudies-literatureUnknown14Kumar PMicroRNAs are small non-coding RNAs that control gene expression during development, physiology, and disease. Transcription is a key factor in microRNA abundance and tissue-specific expression. Many databases predict the location of microRNA transcription start sites and promoters. However, these candidate regions require functional validation. Here, dCas9 fused to transcriptional activators or repressors - CRISPR activation (CRISPRa) and inhibition (CRISPRi)- were targeted to the candidate promoters of two intronic microRNAs, mmu-miR-335 and hsa-miR-3662, including the promoters of their respective host genes Mest and HBS1L. We report that in mouse embryonic stem cells and brain organoids, miR-335 was downregulated upon CRISPRi of its host gene Mest. Reciprocally, CRISPRa of Mest promoterFrontiers in genetics1147222https://www.ebi.ac.uk/biostudies/studies/S-EPMC10196145biostudies-literatureFunctional mapping of microRNA promoters with dCas9 fused to transcriptional regulators.PMC10196145Lemmers CVarrault ACourtes MLe Digarcher AMonteil ABouschet TLiu RKumar PCoku IHong CWang LfalseFunctional mapping of microRNA promoters with dCas9 fused to transcriptional regulators.MicroRNAs are small non-coding RNAs that control gene expression during development, physiology, and disease. Transcription is a key factor in microRNA abundance and tissue-specific expression. Many databases predict the location of microRNA transcription start sites and promoters. However, these candidate regions require functional validation. Here, dCas9 fused to transcriptional activators or repressors - CRISPR activation (CRISPRa) and inhibition (CRISPRi)- were targeted to the candidate promoters of two intronic microRNAs, mmu-miR-335 and hsa-miR-3662, including the promoters of their respective host genes Mest and HBS1L. We report that in mouse embryonic stem cells and brain organoids, miR-335 was downregulated upon CRISPRi of its host gene Mest. Reciprocally, CRISPRa of Mest promoter2023-01-01T00:00:00Z20232025-04-04T23:07:52.517Z2025-04-04T23:07:52.517ZS-EPMC101961453721442210.3389/fgene.2023.1147222