S1773 Identification of microRNA Expressed in Duodenal and Gastric Mucosa, and Modulation By the Duodenal Ulcerogen Cysteamine

Abstract

MicroRNAs (miRNAs) are non-coding small RNAs, which are found to regulate gene expression in many tissues/organs in various physiologic processes. Cysteamine induces duodenal and rarely gastric ulcers in patients receiving cysteamine for cystinosis or hepatic damage and animal models. The rat model has been widely used to study the pathogenesis and healing of duodenal ulcers. In this study, we have performed miRNA microarray to complement our previous DNA microarray analysis of gene expression in rat duodenal mucosa to identify gene expression changes specifically associated with duodenal ulceration. Goals: To identify molecular pathways leading to duodenal ulcer formation induced by duodenal ulcerogens like cysteamine. Methods and Results: Groups of unfasted Sprague-Dawley female rats (180200g) were given cysteamine-HCl (25mg/100g, once) by gavage. Rats were euthanized by CO2 inhalation 2 hr after cysteamine administration. Proximal duodenal and gastric mucosa was scraped. Total RNA including the miRNA fraction was extracted from mucosal samples and further processed for Exiqon miRCURY microarray (289 rat miRNAs). Real-time PCR was performed to confirm some candidate miRNAs. Eight miRNAs were found to have 4fold or higher difference in expression level between duodenal and gastric mucosa. Among them,miR-215 was reported to be upregulated in Barrett's esophagus and is likely a duodenal/ small intestinal specific miRNA. Cysteamine changed the expression level of 20 miRNAs in duodenal mucosa by over 2-fold; two of these by more than 4-fold. Eleven of them are unpublished novel miRNAs. miR-542-5p was increased more than 8-fold by cysteamine. In silico analysis shows its target genes include insulin-like growth factor 2 receptor, paired-like homeodomain transcription factor 3, RCE1 homolog and hypothetical protein LOC152485. Conclusions: 1) We have identified a group of miRNAs differentially expressed in duodenal and gastric mucosa. 2) Cysteamine modulates the expression of several miRNAs which may control wound healing, tissue repair and angiogenesis. 3) Thus, miRNA analysis provides a new way to study gene expression changes in the pathogenesis of duodenal ulceration.