| Although microRNAs are key regulators of gene expression, few studies have thoroughly evaluated the upstream regulators of microRNA activity. We seek to understand the upstream regulators of miR-142, a microRNA thought to be important for B cell lymphogenesis and lymphocyte proliferation. We performed sequential whole-genome RNAi and focused CRISPR screens in a human B cell line to identify genes affecting miR-142 activity on a reporter construct bearing several perfect binding sites. Top hits include known core microRNA pathway genes, but also other genes such as PSME4, FXR1, SKIV2L, and FAM208A. The observation of FXR1 as a top screen hit is intriguing given that it has been observed to post-transcriptionally promote the expression of several neuronal microRNAs, but has not been demonstrated for other microRNAs in general. The results gathered thus far demonstrate the power of using pooled high-throughput screening and genome-editing approaches to discover regulators of microRNA biogenesis and activity. |
