DNA Hypermethylation Downregulates Telomerase Reverse Transcriptase (TERT) during H. pylori-Induced Chronic Inflammation

Figure 1

DNA methylation downregulates hTERT gene expression during H. pylori infection. (a) AGS gastric epithelial cells were treated with 5′-azacytidine (1 μM) for 3 days before incubation with H. pylori B38 lysate (20 μg·ml⁻¹) for 48 h. Quantification of hTERT gene expression was performed by real-time qPCR. 5′-azacytidine treatment restores hTERT gene expression in cells stimulated with H. pylori B38 lysate. Results are expressed as mean ± SD of at least 2 independent experiments in duplicate. ; one-way ANOVA Kruskal–Wallis test followed by Dunn’s multiple comparison (infected versus uninfected ; ; infected versus azacytidine treated ± infection ; ) (b) Structure of the mTERT gene-promoter region in mice, containing a CpG island (hatched box, I and E-box element (black box, II)). (c) DNA methylation status of mTERT-promoter regions analysed by promoter methylation PCR assay, on genomic DNA isolated from the gastric mucosa of H. pylori SS1-infected (18 months) and uninfected mice, as described in the Experimental procedures. A representative gel of amplified methylated DNA is reported (upper panel) with each well corresponding to one mouse. (d) Quantification for each amplified methylated DNA fragment using BIO-PROFIL Bio-1D++ (Biosystems) software (lower panel), showing H. pylori-induced DNA hypermethylation in both mTERT-promoter regions I and II.

(a)

(b)

(c)

(d)