MicroRNA-195 regulates Tuft cell function in the intestinal epithelium by altering translation of DCLK1

Intestinal Tuft cells sense luminal contents to influence the mucosal immune response against eukaryotic infection. Paneth cells secrete antimicrobial proteins as part of the mucosal protective barrier. Defects in Tuft and Paneth cells occur commonly in various gut mucosal disorders. MicroRNA-195 (miR-195) regulates the stability and translation of target mRNAs and is involved in many aspects of cell processes and pathologies. Here, we reported the posttranscriptional mechanisms by which miR-195 regulates Tuft and Paneth cell function in the small intestinal epithelium. Mucosal tissues from intestinal epithelial tissue-specific miR-195 transgenic (miR195-Tg) mice had reduced numbers of double cortin-like kinase 1 (DCLK1)-positive (Tuft) and lysozyme-positive (Paneth) cells, compared with tissues from control mice, but there were no effects on Goblet cells and enterocytes. Intestinal organoids expressing higher miR-195 levels from miR195-Tg mice also exhibited fewer Tuft and Paneth cells. Transgenic expression of miR-195 in mice failed to alter growth of the small intestinal mucosa but increased vulnerability of the gut barrier in response to lipopolysaccharide (LPS). Studies aimed at investigating the mechanism underlying regulation of Tuft cells revealed that miR-195 directly interacted with the Dclk1 mRNA via its 3'-untranslated region and inhibited DCLK1 translation. Interestingly, the RNA-binding protein HuR competed with miR-195 for binding Dclk1 mRNA and increased DCLK1 expression. These results indicate that miR-195 suppresses the function of Tuft and Paneth cells in the small intestinal epithelium and further demonstrate that increased miR-195 disrupts Tuft cell function by inhibiting DCLK1 translation via interaction with HuR.