MiR-7 controls intestinal epithelial proliferation in Drosophila midgut in vivo. (A) Mature miR-7 sequence across different species, including human, pig, mouse, and fruit fly. The seed sequence is denoted in red. (B) Heatmap results of small RNA-seq analysis of Drosophila melanogaster midgut showing miRNAs that are significantly (P < .05) upregulated or downregulated upon exposure to the pro-proliferative Ecc15 pathogen (n = 3) relative to unchallenged (UC) condition (n = 3). Only showing those miRNAs with average reads per million mapped to miRNAs >100 in either Ecc15 challenge or UC. (C) Downregulation of miR-7 in the D. melanogaster midgut at 4 hours (minimal proliferative response, n = 3) and 12 hours (peak proliferative response, n = 3) after Ecc15 challenge compared with the UC control group. (D) Immunofluorescent staining of DAPI (blue) and Esg (green) in D. melanogaster midgut with mock (left), Ecc15 alone (middle), and Ecc15 with miR-7 overexpression driven by the Esg promoter (overexpressed miR-7 [miR-7 OE]) (right). (E) Bar graph showing counts of PH3+ replicating cells in the D. melanogaster midgut of each. * P < .05, ** P < .01, and *** P < .001 by 2-tailed Student t test.