The aims are to investigate the gastric physiology of the gastric pathogen Helicobacter pylori.
Specific Aims : (A). Identify the acid response regulon and signaling system of the cytoplasmic pH sensor. HP0244 is a previously unsuspected sensor of cytoplasmic pH. Using transcriptome analysis after pH 2.5 incubation, the HP0244, HP0703 independent, regulon will be identified to separate periplasmic (HP0165) from cytoplasmic pH) regulation and confirmed by qPCR;(B) Identify colonization dependent gene expression and evaluate pH control of their expression by comparative transcriptome analysis of H. pylori from infected gerbils with and without acid suppression. Transcriptome analysis of H. pylori infecting the gerbil stomach compared to in vitro cultured H. pylori showed a greater up-regulation of genes encoding proteins involved in acid acclimation than at pH 4.5 in vitro, likely reflecting a pH <4.5 in the niche of the colonizing organisms. Cell division, wall and protein biosynthesis genes were also increased. Preliminary data show that acid inhibition by a PPI reduces expression of the former group to the level found at pH 4.5 in vitro but augments expression of the latter three groups of growth-related genes, this may explain the need for a combination of a PPI with growth-dependent antibiotics for triple therapy. These data may lead to dual therapy with a long acting PPI + amoxicillin;(C) Investigate pH-induced activation and trafficking of a urease complex and other proteins to UreI on the inner membrane and determine whether this is regulated by HP0165 or HP0244 The expression of urease by H. pylori (~10% of total protein) is essential for gastric infections. However, at neutral pH, only 1/3rd of urease is active, 2/3rd is present as inactive apoenzyme. pH-dependent activation of the apoenzyme would provide a more rapid response to acid than de novo synthesis. Preliminary results suggest that there is activation and translocation of urease at acidic pH that is dependent on HP0165. UreI serves as the membrane anchor for the pH- dependent relocation of urease to the inner membrane and this is required for activation of apourease. This research may provide new leads for improvement eradication therapy thereby decreasing the risk of peptic ulcer disease and gastric cancer.

Public Health Relevance

Helicobacter pylori is responsible for peptic ulcers and a fortyfold increased risk of gastric cancer. We shall analyze the physiology of H. pylori in the stomach by investigating signaling systems for genes regulated by gastric pH and the role of urease trafficking and activation in infection. A better understanding of effects of acid inhibition on H. pylori may allow improvement or replacement of triple therapy for eradication.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK053642-14
Application #
8241071
Study Section
Gastrointestinal Cell and Molecular Biology Study Section (GCMB)
Program Officer
Hamilton, Frank A
Project Start
1997-09-30
Project End
2014-03-31
Budget Start
2012-04-01
Budget End
2014-03-31
Support Year
14
Fiscal Year
2012
Total Cost
$268,205
Indirect Cost
$6,877
Name
Brentwood Biomedical Research Institute
Department
Type
DUNS #
197170756
City
Los Angeles
State
CA
Country
United States
Zip Code
90073
Marcus, Elizabeth A; Vagin, Olga; Tokhtaeva, Elmira et al. (2013) Helicobacter pylori impedes acid-induced tightening of gastric epithelial junctions. Am J Physiol Gastrointest Liver Physiol 305:G731-9
Marcus, Elizabeth A; Sachs, George; Scott, David R (2013) The role of ExbD in periplasmic pH homeostasis in Helicobacter pylori. Helicobacter 18:363-72
Goebel, M; Stengel, A; Lambrecht, N W G et al. (2011) Selective gene expression by rat gastric corpus epithelium. Physiol Genomics 43:237-54
Shin, J M; Vagin, O; Munson, K et al. (2011) Erratum to: Molecular mechanisms in therapy of acid-related diseases. Cell Mol Life Sci 68:921
Wen, Yi; Feng, Jing; Scott, David R et al. (2011) A cis-encoded antisense small RNA regulated by the HP0165-HP0166 two-component system controls expression of ureB in Helicobacter pylori. J Bacteriol 193:40-51
Shin, Jai Moo; Inatomi, Nobuhiro; Munson, Keith et al. (2011) Characterization of a novel potassium-competitive acid blocker of the gastric H,K-ATPase, 1-[5-(2-fluorophenyl)-1-(pyridin-3-ylsulfonyl)-1H-pyrrol-3-yl]-N-methylmethanamine monofumarate (TAK-438). J Pharmacol Exp Ther 339:412-20
Sachs, George; Shin, Jai Moo; Hunt, Richard (2010) Novel approaches to inhibition of gastric acid secretion. Curr Gastroenterol Rep 12:437-47
Scott, David R; Marcus, Elizabeth A; Wen, Yi et al. (2010) Cytoplasmic histidine kinase (HP0244)-regulated assembly of urease with UreI, a channel for urea and its metabolites, CO2, NH3, and NH4(+), is necessary for acid survival of Helicobacter pylori. J Bacteriol 192:94-103
Vagin, Olga; Kraut, Jeffrey A; Sachs, George (2009) Role of N-glycosylation in trafficking of apical membrane proteins in epithelia. Am J Physiol Renal Physiol 296:F459-69
Shin, Jai Moo; Sachs, George; Cho, Young-moon et al. (2009) 1-Arylsulfonyl-2-(pyridylmethylsulfinyl) benzimidazoles as new proton pump inhibitor prodrugs. Molecules 14:5247-80

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