TRANSFER RNA MODIFICATION CONTRIBUTE TO PATHOGENESIS OF INTESTINAL INFLAMMATION BY ALTERING EPITHELIAL BARRIERS

Abstract

Abstract BACKGROUNDS Transfer RNA (tRNA) is the most extensively modified RNA in cells. Queuosine (Q)-modification is a fundamental process for fidelity and efficiency of translation from RNA to proteins. In eukaryotes, tRNA-Q-modification relies on the intestinal microbial product queuine. Growing evidence indicates that tRNA modifications play important roles in human diseases, e.g., type 2 diabetes. Q depletion led to endoplasmic reticulum stress in mouse liver. Q-tRNA modifications are dynamic and highly variable depending on the developmental stages and species type and tumorigenesis. However, the health consequences of disturbed availability of queuine and altered Q-tRNA modification remain to be investigated. The effects and mechanisms of Q-tRNA in intestinal bowel diseases (IBD) are unknown. METHODS We explored the Q-tRNA-related tRNA synthetases and expression of Q tRNA ribosyltransferase catalytic subunit 1 (QTRT1) in patients with IBD by investigating human biopsies and reanalyzing datasets. We used several colitis mouse models, organoids, and cultured cells for loss- and gain-of-function studies to investigate the mechanisms of Q-tRNA modifications in intestinal barrier functions, proliferation, and inflammation. RESULTS In ulcerative colitis and Crohn’s disease patients, QTRT1 expression was significantly downregulated. Altered QTRT1-related metabolites were found in human IBD. The four Q-tRNA-related tRNA synthetases, asparaginyl-aspartyl-, histidyl-, and tyrosyl-tRNA synthetase, were decreased in IBD patients. This reduction was further confirmed in DSS-induced colitis and IL10-deficient mice. Reduced QTRT1 was significantly correlated with intestinal junctions, including downregulated β-catenin and upregulated Claudin-2. These alterations were confirmed in vitro by deleting QTRT1 from cells. Queuine treatment significantly enhanced cell junctional functions and reduced inflammation in epithelial cells. CONCLUSION tRNA modifications play an unexplored novel role in the pathogenesis of intestinal inflammation by altering epithelial barriers. Insights into Q-tRNA modification in regulating barrier functions would facilitate the development of targeted interventions for IBD through queuine and tRNA modifications.