Helicobacter pylori-induced changes in miRNA expression in human gastric epithelial cells

H. pylori infection of human gastric epithelial cells (GEC) represses H,K-ATPase alpha subunit (HK-alpha) gene transcription through NF-Kappa B p50 homodimer binding to HK-alpha promoter. The bacterial cagA and slt gene products have been implicated in HK-alpha repression, which facilitates gastric H. pylori colonization and may underlie transient clinical hypochlorhydria. We hypothesized that H. pylori also regulates H,K-ATPase expression post-transcriptionally by micro-RNA interaction with HK-alpha mRNA. Our microarray experiment examined the effect of infection by wildtype H. pylori infection or a delta-cagA H. pylori mutant on miRNA expression of human gastric cells (AGS). Our results indicate that H. pylori infection up-regulates GEC miRNAs that target the HK-alpha 3' UTR and block translation, and that CagA activity is implicated in the miRNA up-regulation. Three types of samples were generated for microarray analysis: 1) AGS cells infected with wildtype H. pylori; 2) AGS cells infected with cagA-deficient H. pylori; 3) a mock-infected sample, prepared as a control by combining total RNA from uninfected AGS cells with total RNA from wildtype H. pylori, with relative eukaryotic and prokaryotic RNA amounts matching those observed in infected samples, based on proportional ribosomal peak heights quantified by Bioanalyzer. Three experimental replicates were generated for each type of treatment.