Long Noncoding RNA uc.173 Promotes Renewal of the Intestinal Mucosa by Inducing Degradation of MicroRNA 195.

BACKGROUND AND AIMS: The mammalian intestinal epithelium self-renews rapidly and homeostasis is preserved via tightly controlled mechanisms. Long noncoding RNAs transcribed from ultraconserved regions (T-UCRs) control different cell functions, but little is known about their role in maintaining the integrity of the intestinal epithelium. We searched for T-UCRs that regulate growth of the intestinal mucosa and investigated the mechanism by which T-UCR uc.173 regulates epithelial renewal.

METHODS: C57BL/6J mice were deprived of food for 48 hours in fasting experiments. Some mice were given intraperitoneal injections of a plasmid encoding LNA-anti-uc.173, to knock down endogenous uc.173. For studies using organoids, primary enterocytes were isolated from the intestine and transfected with the uc.173 transgene to increase uc.173 levels. Intestinal epithelial cells (Caco-2 and IEC-6 lines) were transfected with LNA-anti-uc.173 or uc.173 transgene. We quantified intestinal epithelial renewal based on BrdU incorporation, villus height and crypt depth, and cell number. The association of uc.173 with microRNA 195 (miRNA195) was determined by RNA pull-down assays.

RESULTS: Genome-wide profile analyses identified 21 T-UCRs, including uc.173, that were differentially expressed between intestinal mucosa of fasted vs non-fasted mice. Increasing levels of uc.173 by expression of a transgene increased growth of intestinal epithelial cells and organoids. Decreasing uc.173 levels by LNA-anti-uc.173 in mice reduced renewal of the intestinal epithelium. We found that uc.173 interacted directly with the primary transcript of miRNA195, leading to miRNA195 degradation.

CONCLUSIONS: In analyses of intestinal epithelial cells and mice, we identified uc.173 noncoding RNA that regulates growth of the intestinal mucosa and stimulates intestinal epithelial renewal by reducing levels of miRNA195.