Circular RNA Cdr1as inhibits proliferation and delays injury-induced regeneration of the intestinal epithelium
Hee Kyoung Chung, Lan Xiao, Naomi Han, Jason Chen, Vivian Yao, Cassandra M. Cairns, Benjamin Raufman, Jaladanki N. Rao, Douglas J. Turner, Rosemary Kozar, Myriam Gorospe, Jian-Ying Wang
Hee Kyoung Chung, Lan Xiao, Naomi Han, Jason Chen, Vivian Yao, Cassandra M. Cairns, Benjamin Raufman, Jaladanki N. Rao, Douglas J. Turner, Rosemary Kozar, Myriam Gorospe, Jian-Ying Wang
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Research Article Gastroenterology

Circular RNA Cdr1as inhibits proliferation and delays injury-induced regeneration of the intestinal epithelium

Abstract

Circular RNAs (circRNAs) are highly expressed in the mammalian intestinal epithelium, but their functions remain largely unknown. Here, we identified the circRNA Cdr1as as a repressor of intestinal epithelial regeneration and defense. Cdr1as levels increased in mouse intestinal mucosa after colitis and septic stress, as well as in human intestinal mucosa from patients with inflammatory bowel disease and sepsis. Ablation of the Cdr1as locus from the mouse genome enhanced renewal of the intestinal mucosa, promoted injury-induced epithelial regeneration, and protected the mucosa against colitis. We found approximately 40 microRNAs, including miR-195, differentially expressed between intestinal mucosa of Cdr1as-knockout (Cdr1as–/–) versus littermate mice. Increasing the levels of Cdr1as inhibited intestinal epithelial repair after wounding in cultured cells and repressed growth of intestinal organoids cultured ex vivo, but this inhibition was abolished by miR-195 silencing. The reduction in miR-195 levels in the Cdr1as–/– intestinal epithelium was the result of reduced stability and processing of the precursor miR-195. These findings indicate that Cdr1as reduces proliferation and repair of the intestinal epithelium at least in part via interaction with miR-195 and highlight a role for induced Cdr1as in the pathogenesis of unhealed wounds and disrupted renewal of the intestinal mucosa.

Authors

Hee Kyoung Chung, Lan Xiao, Naomi Han, Jason Chen, Vivian Yao, Cassandra M. Cairns, Benjamin Raufman, Jaladanki N. Rao, Douglas J. Turner, Rosemary Kozar, Myriam Gorospe, Jian-Ying Wang

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Figure 1

Mucosal Cdr1as expression in the intestine associated with various pathologies.

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Mucosal Cdr1as expression in the intestine associated with various patho...
(A) Levels of mucosal Cdr1as and circ30977 in the colons of mice treated with water (control) or 3% DSS for 7 days as measured using Q-PCR. Values are the mean ± SEM (n = 5). *P < 0.05 compared with control mice. (B) Levels of mucosal Cdr1as and circPABPN1 in the small intestine of mice exposed to CLP for 48 hours (n = 5). *P < 0.05 compared with control. (C) Levels of mucosal Cdr1as and circPABPN1 in the small intestine from control littermate and IE-HuR–/– mice (n = 4). *P < 0.05 compared with littermates. (D) Levels of Cdr1as in cultured Caco-2 cells 16 hours after wounding in the presence or absence of cellular polyamines. Cells were exposed to DFMO (5 mmol/L) for 6 days, and the levels of Cdr1as were examined 16 hours after wounding (n = 3). *P < 0.05 and #P < 0.05 compared with 0-hour repair and 16-hour repair of the control group, respectively. (E) Mucosal Cdr1as levels in the colon from patients with ulcerative colitis (UC) and the ileum from patients with Crohn disease (CD) (n = 6). *P < 0.05 compared with controls. (F) In situ hybridization of Cdr1as with fluorescent LNA-RNA detection probe in the small intestinal mucosa in patients with sepsis, as shown in green. Scale bars: 25 μm; arrows indicate Cdr1as staining. Experiments were conducted in 4 control individuals and 4 septic patients and showed similar results. (G) Levels of cytoplasmic (cyto) and nuclear Cdr1as, uc.173, and HULC in Caco-2 cells. Statistical significance was analyzed using unpaired, 2-tailed Student’s t test, except for results in F and G. All experiments in F and G were repeated 3 times with similar results.