Transient receptor potential vanilloid 4 (TRPV4) silencing in Helicobacter pylori‐infected human gastric epithelium

Abstract

Background Helicobacter pylori (HP) infection induces methylation silencing of specific genes in gastric epithelium. Various stimuli activate the nonselective cation channel TRPV4, which is expressed in gastric epithelium where it detects mechanical stimuli and promotes ATP release. As CpG islands in TRPV4 are methylated in HP‐infected gastric epithelium, we evaluated HP infection‐dependent changes in TRPV4 expression in gastric epithelium.Materials and MethodsHuman gastric biopsy samples, a human gastric cancer cell line (AGS), and a normal gastric epithelial cell line (GES‐1) were used to detect TRPV4 mRNA and protein expression by RT‐PCR and Western blotting, respectively. Ca2+ imaging was used to evaluate TRPV4 ion channel activity. TRPV4 methylation status was assessed by methylation‐specific PCR (MSP). ATP release was measured by a luciferin‐luciferase assay.Results TRPV4 mRNA and protein were detected in human gastric biopsy samples and in GES‐1 cells. MSP and demethylation assays showed TRPV4 methylation silencing in AGS cells. HP coculture directly induced methylation silencing of TRPV4 in GES‐1 cells. In human samples, HP infection was associated with TRPV4 methylation silencing that recovered after HP eradication in a time‐dependent manner.Conclusion HP infection‐dependent DNA methylation suppressed TRPV4 expression in human gastric epithelia, suggesting that TRPV4 methylation may be involved in HP‐associated dyspepsia.

Involvement of VNUT-exocytosis in transient receptor potential vanilloid 4-dependent ATP release from gastrointestinal epithelium

“…ATP concentrations released from GES-1 and CCD 841 cells cultured in 12-well plates were measured using a luciferin-luciferase assay (ATP Bioluminescence Assay Kit CLS II, Roche Diagnostics, Basel, Switzerland) and a luminometer (Lumat LB 9507, Berthold Technologies, Japan) with slight modification to previously described methods [ 12 , 14 ]. Cells cultured to 70–80% confluence and incubated in 500 μL bath solution for 30 min at room temperature (25°C) were used to measure basal ATP release.…”

“…TRPV4 is present in diverse tissues including the colon [ 11 ], and we have reported that TRPV4 and VNUT are expressed in mouse esophageal keratinocytes and contribute ATP exocytosis [ 12 ]. Furthermore, TRPV4 activation induces ATP release in gastric epithelial cells [ 13 ] [ 14 ]. However, it is unknown whether TRPV4 activation induces ATP exocytosis from gastric and colonic epithelia.…”

Effect of Yuzu (Citrus junos) Seed Limonoids and Spermine on Intestinal Microbiota and Hypothalamic Tissue in the Sandhoff Disease Mouse Model

“…On the other hand, such extremely biased ratios of Lactobacillus in SD control mice may be implicated in dysbiosis, a condition in which microbiota diversity is reduced primarily because of antibiotic administration, unhealthy dietary intakes, infection, genetic abnormalities, and immune disorders [ 45 ]. Dysbiosis has also been reported to increase the permeability of epithelial cells in the small intestine [ 46 ], and ulcerations attributed to increased permeability of these cells can lead to intestinal inflammation via intestinal microbiota or their associated metabolites. Examples of such dysbiosis have been reported in the case of Parkinson’s disease.…”

Letter to the Editor: “Ion Channels in Brain Metastasis”—Ion Channels in Cancer Set up and Metastatic Progression

“…For instance, we [ 2 ] evaluated the expression of ninety ion-channel genes in 3673 human biopsies, in five different solid tumors (bladder cancer, breast cancer, glioblastoma, lung cancer and melanoma). We [ 2 ] and others [ 3 , 4 , 5 , 6 , 7 , 8 , 9 ] have shown a key role of ion channels in tumors common to Klumpp, L. et al, namely lung cancer, breast cancer and melanoma, as well as in other cancers such as glioblastoma, bladder cancer and colorectal cancer. These channels are calcium channel voltage-dependent (CACNA1D); FXYD domain-containing ion transport regulators (FXYD3, FXYD5); chloride intracellular channels (CLIC1); glutamate receptors (HTR3A); potassium channel voltage-gated channels (KCNE3, KCNE4, KCNN4); transient receptor potential cation channels (TRPA1, TRPC5, TRPM3, TRPV4) and Aquaporins (AQPs).…”

“…Such a list may somehow integrate the scenario depicted by Klumpp, L. et al As we underlined in our study, all such cancers have different histological origin but they have endothelial and vascular alterations in common. The role of ion channels in vascular alteration occurring in the metastatic process is clearly recognized but still not completely elucidated, as discussed by Klumpp, L. et al Therefore, we believe that all these ion channels reported by Klumpp, L. et al [ 1 ]., us [ 2 ] and others [ 3 , 4 , 5 , 6 , 7 , 8 , 9 ] may have a mechanistic role in the primary tumor set up as well as in the metastatic progression toward the brain and other organs.…”