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Lee YHG, Cerf NT, Shalaby N, Montes MR, Clarke RJ. Bioinformatic Study of Possible Acute Regulation of Acid Secretion in the Stomach. J Membr Biol 2024; 257:79-89. [PMID: 38436710 PMCID: PMC11006737 DOI: 10.1007/s00232-024-00310-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2023] [Accepted: 02/21/2024] [Indexed: 03/05/2024]
Abstract
The gastric H+,K+-ATPase is an integral membrane protein which derives energy from the hydrolysis of ATP to transport H+ ions from the parietal cells of the gastric mucosa into the stomach in exchange for K+ ions. It is responsible for the acidic environment of the stomach, which is essential for digestion. Acid secretion is regulated by the recruitment of the H+,K+-ATPase from intracellular stores into the plasma membrane on the ingestion of food. The similar amino acid sequences of the lysine-rich N-termini α-subunits of the H+,K+- and Na+,K+-ATPases, suggests similar acute regulation mechanisms, specifically, an electrostatic switch mechanism involving an interaction of the N-terminal tail with the surface of the surrounding membrane and a modulation of the interaction via regulatory phosphorylation by protein kinases. From a consideration of sequence alignment of the H+,K+-ATPase and an analysis of its coevolution with protein kinase C and kinases of the Src family, the evidence points towards a phosphorylation of tyrosine-7 of the N-terminus by either Lck or Yes in all vertebrates except cartilaginous fish. The results obtained will guide and focus future experimental research.
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Affiliation(s)
- Yan Hay Grace Lee
- School of Chemistry, University of Sydney, Sydney, NSW, 2006, Australia
| | - Nicole T Cerf
- Instituto de Química y Fisicoquímica Biológica (IQUIFIB), CONICET, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Nicholas Shalaby
- School of Chemistry, University of Sydney, Sydney, NSW, 2006, Australia
| | - Mónica R Montes
- Instituto de Química y Fisicoquímica Biológica (IQUIFIB), CONICET, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Ronald J Clarke
- School of Chemistry, University of Sydney, Sydney, NSW, 2006, Australia.
- The University of Sydney Nano Institute, Sydney, NSW, 2006, Australia.
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2
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Esfandiyari K, Pfeifer LJ, Farahani MA, Malakpour Kolbadinezhad S, Castro LF, Wilson JM. The gastric proton pump in gobiid and mudskipper fishes. Evidence of stomach loss? Comp Biochem Physiol A Mol Integr Physiol 2022; 274:111300. [PMID: 36031062 DOI: 10.1016/j.cbpa.2022.111300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 08/20/2022] [Accepted: 08/21/2022] [Indexed: 01/01/2023]
Abstract
Stomach loss has occurred independently multiple times during gnathostome evolution with notable frequency within the Teleostei. Significantly, this loss of acid-peptic digestion has been found to correlate with the secondary genomic loss of the gastric proton pump subunits (atp4a, atp4b) and pepsinogens/pepsins (pga, pgc). Gastric glands produce gastric juice containing the acid and pepsin and thus their presence is a hallmark feature of a digestive system capable of acid-peptic digestion. However, in gobiid fishes although oesogaster and gastric glands have been identified histologically, their functional significance has been questioned. In the present study we address whether the gastric proton pump is present and expressed in gastric glands of the goby Neogobius species (Gobiidae) and in members of the family Oxudercidae, a group of amphibious gobiid fishes commonly known as mudskippers (genera: Periophthalmus, Boleophthalmus, Periophthalmodon and Scartelaos). We confirmed the presence of gastric glands and have immunohistochemically localized gastric proton pump expression to these glands in Neogobius fluviatilis and Periophthalmus novemradiatus, Periophthalmus barbarus and Boleophthalmus boddarti. Genome analysis in Neogobius melanostomus, Periophthalmus magnuspinnatus, Scartelaos histophorus, Boleophthalmus pectinirostris, and Periophthalmodon schlosseri revealed the presence of both atp4a and atp4b subunit orthologues in all species in a conserved genomic loci organization. Moreover, it was possible to deduce that the complete open reading frame and the key functional amino acid residues are present. The conserved expression of the gastric proton pump provides clear evidence of the potential for gastric acid secretion indicating that acid digestion is retained in these gobiid fishes and not lost.
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Fujii T, Sugimoto K, Noda T, Shimizu T, Matsuya Y, Sakai H. Inhibition of gastric H +,K +-ATPase by new dihydropyrazole derivative KYY-008. Biochem Biophys Res Commun 2021; 567:177-182. [PMID: 34166915 DOI: 10.1016/j.bbrc.2021.06.056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Accepted: 06/16/2021] [Indexed: 12/12/2022]
Abstract
The gastric proton pump (H+,K+-ATPase) responsible for the H+ secretion of gastric acid is an essential therapeutic target for acid-related diseases. H+,K+-ATPase belongs to a P2-type ATPase family. Here, we examined the effects of a newly synthesized dihydropyrazole derivative KYY-008 on the H+,K+-ATPase. KYY-008 concentration-dependently inhibited the enzyme activity of the ATPase in the membrane fractions prepared from isolated hog gastric mucosa and from human kidney HEK293 cells in which gastric H+,K+-ATPase is exogenously expressed. The IC50 values in these samples were 3.4 μM and 3.7 μM, respectively. In addition, KYY-008 significantly inhibited the H+,K+-ATPase-derived H+ uptake into the tightly sealed vesicles prepared from the hog gastric mucosa. In contrast, KYY-008 has no effect on the activities of other P2-type ATPases such as Na+,K+-ATPase and Ca2+-ATPase. KYY-008 did not change the ionic currents of voltage-dependent Ca2+ channels, that were potential targets for some dihydropyrazole derivatives. Together, we discovered a new dihydropyrazole derivative which acts as a selective inhibitor of gastric H+,K+-ATPase.
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Affiliation(s)
- Takuto Fujii
- Department of Pharmaceutical Physiology, Faculty of Pharmaceutical Sciences, University of Toyama, Toyama, 930-0194, Japan.
| | - Kenji Sugimoto
- Department of Synthetic and Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama, Toyama, 930-0194, Japan
| | - Takafumi Noda
- Department of Pharmaceutical Physiology, Faculty of Pharmaceutical Sciences, University of Toyama, Toyama, 930-0194, Japan
| | - Takahiro Shimizu
- Department of Pharmaceutical Physiology, Faculty of Pharmaceutical Sciences, University of Toyama, Toyama, 930-0194, Japan
| | - Yuji Matsuya
- Department of Synthetic and Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama, Toyama, 930-0194, Japan
| | - Hideki Sakai
- Department of Pharmaceutical Physiology, Faculty of Pharmaceutical Sciences, University of Toyama, Toyama, 930-0194, Japan
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Diaz D, Clarke RJ. Evolutionary Analysis of the Lysine-Rich N-terminal Cytoplasmic Domains of the Gastric H +,K +-ATPase and the Na +,K +-ATPase. J Membr Biol 2018; 251:653-666. [PMID: 30056551 DOI: 10.1007/s00232-018-0043-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 07/19/2018] [Indexed: 12/16/2022]
Abstract
The catalytic α-subunits of both the Na+,K+-ATPase and the gastric H+,K+-ATPase possess lysine-rich N-termini which project into the cytoplasm. Due to conflicting experimental results, it is currently unclear whether the N-termini play a role in ion pump function or regulation, and, if they do, by what mechanism. Comparison of the lysine frequencies of the N-termini of both proteins with those of all of their extramembrane domains showed that the N-terminal lysine frequencies are far higher than one would expect simply from exposure to the aqueous solvent. The lysine frequency was found to vary significantly between different vertebrate classes, but this is due predominantly to a change in N-terminal length. As evidenced by a comparison between fish and mammals, an evolutionary trend towards an increase of the length of the N-terminus of the H+,K+-ATPase on going from an ancestral fish to mammals could be identified. This evolutionary trend supports the hypothesis that the N-terminus is important in ion pump function or regulation. In placental mammals, one of the lysines is replaced by serine (Ser-27), which is a target for protein kinase C. In most other animal species, a lysine occupies this position and hence no protein kinase C target is present. Interaction with protein kinase C is thus not the primary role of the lysine-rich N-terminus. The disordered structure of the N-terminus may, via increased flexibility, facilitate interaction with another binding partner, e.g. the surrounding membrane, or help to stabilise particular enzyme conformations via the increased entropy it produces.
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Affiliation(s)
- Dil Diaz
- School of Chemistry, University of Sydney, Sydney, NSW, 2006, Australia
| | - Ronald J Clarke
- School of Chemistry, University of Sydney, Sydney, NSW, 2006, Australia. .,The University of Sydney Nano Institute, Sydney, NSW, 2006, Australia.
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Jana K, Bandyopadhyay T, Ganguly B. Designed inhibitors with hetero linkers for gastric proton pump H +,K +-ATPase: Steered molecular dynamics and metadynamics studies. J Mol Graph Model 2017; 78:129-138. [PMID: 29055186 DOI: 10.1016/j.jmgm.2017.10.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 10/06/2017] [Accepted: 10/09/2017] [Indexed: 02/07/2023]
Abstract
Acid suppressant SCH28080 and its derivatives reversibly reduce acid secretion activity of the H+,K+-ATPase in a K+ competitive manner. The results on homologation of the SCH28080 by varying the linker chain length suggested the improvement in efficacy. However, the pharmacokinetic studies reveal that the hydrophobic nature of the CH2 linker units may not help it to function as a better acid suppressant. We have exploited the role of linker unit to enhance the efficacy of such reversible acid suppressant drug molecules using hetero linker, i.e., disulfide and peroxy linkers. The logarithm of partition coefficient defined for a drug molecule relates to the partition coefficient, which allows the optimum solubility characteristics to reach the active site. The logarithm of partition coefficient calculated for the designed inhibitors suggests that inhibitors would possibly reach the active site in sufficient concentration like in the case of SCH28080. The steered molecular dynamics studies have revealed that the Inhibitor-1 with disulfide linker unit is more stable at the active site due to greater noncovalent interactions compared to the SCH28080. Centre of mass distance analysis suggests that the Cysteine-813 amino acid residue selectively plays an important role in the inhibition of H+,K+-ATPase for Inhibitor-1. Furthermore, the quantum chemical calculations with M11L/6-31+G(d,p) level of theory have been performed to account the noncovalent interactions responsible for the stabilization of inhibitor molecules in the active site gorge of the gastric proton pump at different time scale. The hydrogen bonding and hydrophobic interaction studies corroborate the center of mass distance analysis as well. Well-tempered metadynamics free energy surface and center of mass separation analysis for the Inhibitor-1 is in good agreement with the steered molecular dynamics results. The torsional angle of the linker units seems to be crucial for better efficacy of drug molecules. The torsional angle of linker units of SCH28080 (COCH2C) and of Inhibitor 1 (CSSC) prefers to lie within ∼60°-90° for a longer time during the simulations, whereas, the peroxy linker (COOC) of Inhibitor 2 prefers to adopt ∼120-160°. Therefore, it appears that the smaller torsion angle of linker units can achieve better interactions with the active site residues of H+,K+-ATPase to inhibit the acid secretion activity. The reversible drug molecules with disulfide linker unit would be a promising candidate as proton pump antagonist to H+,K+-ATPase.
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Affiliation(s)
- Kalyanashis Jana
- Computation and Simulation Unit (Analytical Discipline and Centralized Instrument Facility), CSIR, Central Salt and Marine Chemicals Research Institute, Bhavnagar 364002, Gujarat, India; Academy of Scientific and Innovative Research, CSIR, CSMCRI, Bhavnagar 364002, Gujarat, India
| | - Tusar Bandyopadhyay
- Theoretical Chemistry Section, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India.
| | - Bishwajit Ganguly
- Computation and Simulation Unit (Analytical Discipline and Centralized Instrument Facility), CSIR, Central Salt and Marine Chemicals Research Institute, Bhavnagar 364002, Gujarat, India; Academy of Scientific and Innovative Research, CSIR, CSMCRI, Bhavnagar 364002, Gujarat, India.
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Fossmark R, Calvete O, Mjønes P, Benitez J, Waldum HL. ECL-cell carcinoids and carcinoma in patients homozygous for an inactivating mutation in the gastric H(+) K(+) ATPase alpha subunit. APMIS 2016; 124:561-6. [PMID: 27150581 DOI: 10.1111/apm.12546] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 03/30/2016] [Indexed: 02/07/2023]
Abstract
A family with a missense variant of the ATP4A gene encoding the alpha subunit of the gastric proton pump (H(+) K(+) ATPase) has recently been described. Homozygous siblings were hypergastrinemic (median gastrin 486 pM) and had gastric tumours diagnosed at a median age of 33 years. In the current histopathological study, we further characterized the tumours found in the gastric corpus. The tumours had the histological appearance of carcinoids (NET G1 or G2) and were immunoreactive for the general neuroendocrine markers chromogranin A (CgA) and synaptophysin as well as the ECL-cell markers vesicular monoamine transporter 2 (VMAT2) and histidine decarbozylase (HDC). One of the tumours consisted of a NET G2 component, but also had a component with glandular growth, which morphologically was classified as an intestinal type adenocarcinoma. Many glands of the adenocarcinoma contained a large proportion of cells positive for neuroendocrine markers, especially the small vesicle marker synaptophysin and the cytoplasmic enzyme HDC. In conclusion, patients homozygous for an inactivating ATP4A mutation develop gastric ECL-cell carcinoids in their 3rd or 4th decade. The adenocarcinoma may be classified as neuroendocrine with ECL-cell differentiation.
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Affiliation(s)
- Reidar Fossmark
- Department of Gastroenterology and Hepatology, St. Olav's Hospital, Trondheim, Norway.,Department of Cancer Research and Molecular Medicine, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Oriol Calvete
- Human Genetics Group, Spanish National Cancer Research Center (CNIO), Madrid, Spain.,Network of Research on Rare Diseases (CIBERER), Madrid, Spain
| | - Patricia Mjønes
- Department of Cancer Research and Molecular Medicine, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.,Department of Pathology, St. Olav's Hospital, Trondheim, Norway
| | - Javier Benitez
- Human Genetics Group, Spanish National Cancer Research Center (CNIO), Madrid, Spain.,Network of Research on Rare Diseases (CIBERER), Madrid, Spain
| | - Helge L Waldum
- Department of Gastroenterology and Hepatology, St. Olav's Hospital, Trondheim, Norway.,Department of Cancer Research and Molecular Medicine, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway
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Fossmark R, Rao S, Mjønes P, Munkvold B, Flatberg A, Varro A, Thommesen L, Nørsett KG. PAI-1 deficiency increases the trophic effects of hypergastrinemia in the gastric corpus mucosa. Peptides 2016; 79:83-94. [PMID: 27038741 DOI: 10.1016/j.peptides.2016.03.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 03/18/2016] [Accepted: 03/29/2016] [Indexed: 12/16/2022]
Abstract
The gastric hormone gastrin plays a role in organizing the gastric mucosa. Gastrin also regulates the expression of genes that have important actions in extracellular matrix modelling, including plasminogen activator inhibitor (PAI)-1 which is part of the urokinase plasminogen activator (uPA) system. The uPA system (including PAI-1) is associated with cancer progression, fibrosis and thrombosis. Its biological role in the stomach and molecular mechanisms of action are not well understood. The aim of this study was to examine the effect of PAI-1 on the trophic changes observed in gastric corpus mucosa in hypergastrinemia using PAI-1 and/or HK-ATPase beta subunit knockout (KO) mice. HK-ATPase beta subunit KO mice were used as a model of hypergastrinemia. In 12 month old female mice, intragastric acidity and plasma gastrin were measured. The stomachs were examined for macroscopic and histological changes. In mice null for both PAI-1 and HK-ATPase beta (double KO), there was exaggerated hypergastrinemia, increased stomach weight and corpus mucosal thickness, and more pronounced trophic and architectural changes in the corpus compared with HK-ATPase beta KO mice. Genome-wide microarray expression data for the gastric corpus mucosa showed a distinct gene expression profile for the HK-ATPase beta KO mice; moreover, enrichment analysis revealed changes in expression of genes regulating intracellular processes including cytoskeleton remodelling, cell adhesion, signal transduction and epithelial-to-mesenchymal transition (EMT). Genes differentially expressed in the double KO compared with HK-ATPase beta KO mice included the transcription factor Barx2 and the chromatin remodeler gene Tet2, which may be involved in both normal gastric physiology and development of gastric cancer. Based on the present data, we suggest that PAI-1 plays a role in maintaining gastric mucosal organization in hypergastrinemia.
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Affiliation(s)
- Reidar Fossmark
- Department of Cancer Research and Molecular Medicine, NTNU, Trondheim, Norway; Department of Gastroenterology and Hepatology, St. Olav's University Hospital, Trondheim, Norway.
| | - Shalini Rao
- Department of Cancer Research and Molecular Medicine, NTNU, Trondheim, Norway.
| | - Patricia Mjønes
- Department of Cancer Research and Molecular Medicine, NTNU, Trondheim, Norway; Department of Pathology, St. Olav's University Hospital, Trondheim, Norway.
| | - Bjørn Munkvold
- Department of Cancer Research and Molecular Medicine, NTNU, Trondheim, Norway.
| | - Arnar Flatberg
- Department of Cancer Research and Molecular Medicine, NTNU, Trondheim, Norway.
| | - Andrea Varro
- Department of Cell and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom.
| | - Liv Thommesen
- Department of Cancer Research and Molecular Medicine, NTNU, Trondheim, Norway.
| | - Kristin G Nørsett
- Department of Cancer Research and Molecular Medicine, NTNU, Trondheim, Norway; The Central Norway Regional Health Authority, Trondheim, Norway.
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Abstract
Gastric H(+),K(+)-ATPase is an ATP-driven proton pump responsible for the acid secretion. Here, we describe the procedure for the isolation of H(+),K(+)-ATPase-enriched membrane vesicle fractions by Ficoll/sucrose density gradient centrifugation. Further purification by SDS treatment of membrane fractions is also introduced. These procedures allow us to obtain purified protein preparations in a quantity of several tens of milligrams, with the specific activity of ~480 μmol/mg/h. High purity and stability of H(+),K(+)-ATPase in the membrane preparation enable us to evaluate its detailed biochemical properties, and also to obtain 2D crystals for structural analysis.
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Abe K. Two-Dimensional Crystallization of Gastric H(+),K(+)-ATPase for Structural Analysis by Electron Crystallography. Methods Mol Biol 2016; 1377:443-55. [PMID: 26695054 DOI: 10.1007/978-1-4939-3179-8_39] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Electron crystallography of two-dimensional (2D) crystals has provided important information on the structural biology of P-type ATPases. Here, I describe the procedure for making 2D crystals of gastric H(+),K(+)-ATPase purified from pig stomach. The 2D crystals are produced by dialyzing detergent-solubilized H(+),K(+)-ATPase mixed with synthetic phospholipids. Removal of the detergent induces the reconstitution of H(+),K(+)-ATPase molecules into the lipid bilayer. In the presence of fluorinated phosphate analogs, or in combination with transporting cations or the specific antagonist SCH28080, H(+),K(+)-ATPase forms crystalline 2D arrays. The molecular conformation and morphology of the 2D crystals vary depending on the crystallizing conditions. Using these 2D crystals, three-dimensional structures of H(+),K(+)-ATPase can be generated by data correction from ice-embedded 2D crystals using cryo-electron microscopy, followed by processing the recorded images using electron crystallography methods.
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