title: Effects of Helicobacter pylori on intracellular Ca2+ signaling in normal human gastric mucous epithelial cells.
abstract: In stomach, Helicobacter pylori (Hp) adheres to gastric mucous epithelial cells (GMEC) and initiates several different signal transduction events. Alteration of intracellular Ca2+ concentration ([Ca2+]i) is an important signaling mechanism in numerous bacteria-host model systems. Changes in [Ca2+]i induced by Hp in normal human GMEC have not yet been described; therefore, we examined effects of Hp on [Ca2+]i in normal human GMEC and a nontransformed GMEC line (HFE-145). Cultured cells were grown on glass slides, porous filters, or 96-well plates and loaded with fura 2 or fluo 4. Hp wild-type strain 60190 and vacA-, cagA-, and picB-/cagE- isogenic mutants were incubated with cells. Changes in [Ca2+]i were recorded with a fluorimeter or fluorescence plate reader. Wild-type Hp produced dose-dependent biphasic transient [Ca2+]i peak and plateau changes in both cell lines. Hp vacA- isogenic mutant produced changes in [Ca2+]i similar to those produced by wild type. Compared with wild type, cagA- and picB-/cagE- isogenic mutants produced lower peak changes and did not generate a plateau change. Preloading cultures with intracellular Ca2+ chelator BAPTA blocked all Hp-induced [Ca2+]i changes. Thapsigargin pretreatment of cultures to release Ca2+ from internal stores reduced peak change. Extracellular Ca2+ removal reduced plateau response. Hp-induced peak response was sensitive to G proteins and PLC inhibitors. Hp-induced plateau change was sensitive to G protein inhibitors, src kinases, and PLA2. These findings are the first to show that H. pylori alters [Ca2+]i in normal GMEC through a Ca2+ release/influx mechanism that depends on expression of cagA and picB/cagE genes.
authors.affiliation: Department of Surgery, Oregon Health Sciences University, 3181 Sam Jackson Park Road, Portland, OR 97201, USA.
authors.forename: Katie L
authors.initials: KL
authors.lastname: Marlink
authors.forename: Kathy D
authors.initials: KD
authors.lastname: Bacon
authors.forename: Brett C
authors.initials: BC
authors.lastname: Sheppard
authors.forename: Hassan
authors.initials: H
authors.lastname: Ashktorab
authors.forename: Duane T
authors.initials: DT
authors.lastname: Smoot
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Cover
authors.forename: Clifford W
authors.initials: CW
authors.lastname: Deveney
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Rutten
mesh_terms: D000942:Antigens, Bacterial / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology*; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism / Q000382:microbiology*; D019204:GTP-Binding Proteins / Q000378:metabolism; D005753:Gastric Mucosa / Q000166:cytology / Q000378:metabolism / Q000382:microbiology*; D005798:Genes, Bacterial / Q000502:physiology; D016481:Helicobacter Infections / Q000378:metabolism* / Q000382:microbiology; D016480:Helicobacter pylori / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D010741:Phospholipases A / Q000378:metabolism; D054467:Phospholipases A2; D010738:Type C Phospholipases / Q000378:metabolism; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C103937:PicB protein, Helicobacter pylori; C074689:VacA protein, Helicobacter pylori; C080866:cagA protein, Helicobacter pylori; D019061:src-Family Kinases; D010741:Phospholipases A; D054467:Phospholipases A2; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; D002118:Calcium