摘要：SummaryMicroRNAs (miRNAs) are short non-coding RNA molecules that regulate gene expression post-transcriptionally by binding to target messenger RNAs (mRNAs). Many human miRNAs are intragenic, located within introns of protein-coding sequence (host). Intriguingly, a percentage of intragenic miRNAs downregulate the host transcript forming an incoherent feedforward motif topology. Here, we study intragenic miRNA-mediated host gene regulation using a synthetic gene circuit stably integrated within a safe-harbor locus of human cells. When the intragenic miRNA is directed to inhibit the host transcript, we observe a reduction in reporter expression accompanied by output filtering and noise reduction. Specifically, the system operates as a filter with respect to promoter strength, with the threshold being robust to promoter strength and measurement time. Additionally, the intragenic miRNA regulation reduces expression noise compared to splicing-alone architecture. Our results provide a new insight into miRNA-mediated gene expression, with direct implications to gene therapy and synthetic biology applications.Graphical AbstractDisplay OmittedHighlights•Intragenic miRNA-based host regulation was recreated using a synthetic miRNA•The system was integrated in HEK293 cells via CRISPR-based safe-harbor integration•The system generates a gene expression threshold robust to host promoter strength•Host gene output has reduced noise compared to a splicing-alone architectureBiological Sciences; Molecular Biology; Molecular Mechanism of Gene Regulation
