Noncoding Vault RNA1-1 Impairs Intestinal Epithelial Renewal and Barrier Function by Interacting with CUG-binding Protein 1.

Abstract

Background & aims: Small noncoding vault RNAs (vtRNAs) are involved in many cell processes important for health and disease, but their pathobiological functions in the intestinal epithelium are underexplored. Here, we investigated the role of human vtRNA1-1 in regulating intestinal epithelial renewal and barrier function.

Methods: Studies were conducted in vtRNA1-1 transgenic (vtRNA1-1Tg) mice, primary enterocytes, and Caco-2 cells. Extracellular vesicles (EVs) were isolated from the serum of shock patients and septic mice. Intestinal organoids (enteroids) were prepared from vtRNA1-1Tg and littermate mice. Mucosal growth was measured by Ki67 immunostaining or BrdU incorporation, and gut permeability assessed using the FITC-dextran assay.

Results: Intestinal tissues recovered from shock patients and septic mice evidenced mucosal injury and gut barrier dysfunction; vtRNA levels were elevated in EVs isolated from their sera. In mice, intestinal epithelial-specific transgenic expression of vtRNA1-1 inhibited mucosal growth, reduced Paneth cell numbers and intercellular junction (IJ) protein expression, and increased gut barrier vulnerability to lipopolysaccharide exposure. Conversely, in vitro silencing of vtRNA1-1 increased IJ protein levels and enhanced epithelial barrier function. Exposing enteroids to vtRNA1-1-rich EVs augmented paracellular permeability. Mechanistically, vtRNA1-1 interacted with CUG-binding protein 1 (CUGBP1) and increased CUGBP1 association with claudin-1 and occludin mRNAs, thereby inhibiting their expression.

Conclusions: These findings indicate that elevated levels of vtRNA1-1 in EVs and mucosal tissues repress intestinal epithelial renewal and barrier function. Notably, this work reveals a novel role for dysregulation of the vtRNA1-1/CUGBP1 axis in the pathogenesis of gut mucosal disruption in critical illness.