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Kunzelmann K, Centeio R, Ousingsawat J, Talbi K, Seidler U, Schreiber R. SLC26A9 in airways and intestine: secretion or absorption? Channels (Austin) 2023; 17:2186434. [PMID: 36866602 PMCID: PMC9988340 DOI: 10.1080/19336950.2023.2186434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/04/2023] Open
Abstract
SLC26A9 is one out of 11 proteins that belong to the SLC26A family of anion transporters. Apart from expression in the gastrointestinal tract, SLC26A9 is also found in the respiratory system, in male tissues and in the skin. SLC26A9 has gained attention because of its modifier role in the gastrointestinal manifestation of cystic fibrosis (CF). SLC26A9 appears to have an impact on the extent of intestinal obstruction caused by meconium ileus. SLC26A9 supports duodenal bicarbonate secretion, but was assumed to provide a basal Cl- secretory pathway in airways. However, recent results show that basal airway Cl- secretion is due to cystic fibrosis conductance regulator (CFTR), while SLC26A9 may rather secrete HCO3-, thereby maintaining proper airway surface liquid (ASL) pH. Moreover, SLC26A9 does not secrete but probably supports reabsorption of fluid particularly in the alveolar space, which explains early death by neonatal distress in Slc26a9-knockout animals. While the novel SLC26A9 inhibitor S9-A13 helped to unmask the role of SLC26A9 in the airways, it also provided evidence for an additional role in acid secretion by gastric parietal cells. Here we discuss recent data on the function of SLC26A9 in airways and gut, and how S9-A13 may be useful in unraveling the physiological role of SLC26A9.
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Affiliation(s)
- Karl Kunzelmann
- Institut für Physiologie, Universität, Universitätsstraße 31, Regensburg, Germany
- CONTACT Karl Kunzelmann
| | - Raquel Centeio
- Institut für Physiologie, Universität, Universitätsstraße 31, Regensburg, Germany
| | - Jiraporn Ousingsawat
- Institut für Physiologie, Universität, Universitätsstraße 31, Regensburg, Germany
| | - Khaoula Talbi
- Institut für Physiologie, Universität, Universitätsstraße 31, Regensburg, Germany
| | - Ursula Seidler
- Department of Gastroenterology, Hannover Medical School, Hannover, Germany
| | - Rainer Schreiber
- Institut für Physiologie, Universität, Universitätsstraße 31, Regensburg, Germany
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2
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Pathophysiological role of ion channels and transporters in gastrointestinal mucosal diseases. Cell Mol Life Sci 2021; 78:8109-8125. [PMID: 34778915 PMCID: PMC8629801 DOI: 10.1007/s00018-021-04011-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 09/10/2021] [Accepted: 10/23/2021] [Indexed: 11/13/2022]
Abstract
The incidence of gastrointestinal (GI) mucosal diseases, including various types of gastritis, ulcers, inflammatory bowel disease and GI cancer, is increasing. Therefore, it is necessary to identify new therapeutic targets. Ion channels/transporters are located on cell membranes, and tight junctions (TJs) affect acid–base balance, the mucus layer, permeability, the microbiota and mucosal blood flow, which are essential for maintaining GI mucosal integrity. As ion channel/transporter dysfunction results in various GI mucosal diseases, this review focuses on understanding the contribution of ion channels/transporters to protecting the GI mucosal barrier and the relationship between GI mucosal disease and ion channels/transporters, including Cl−/HCO3− exchangers, Cl− channels, aquaporins, Na+/H+ exchangers, and K+ channels. Here, we provide novel prospects for the treatment of GI mucosal diseases.
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3
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Fujii T. [Different Membrane Environments Generate Multiple Functions of P-type Ion Pumps]. YAKUGAKU ZASSHI 2021; 141:1217-1222. [PMID: 34719540 DOI: 10.1248/yakushi.21-00135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
P-type ion pumps (P-type ATPases) are involved in various fundamental biological processes. For example, the gastric proton pump (H+,K+-ATPase) and sodium pump (Na+,K+-ATPase) are responsible for secretion of gastric acid and maintenance of cell membrane potential, respectively. In this review, we summarize three topics of our studies. The first topic is gastric H+,K+-ATPase associated with Cl--transporting proteins (Cl-/H+ exchanger ClC-5 and K+-Cl- cotransporter KCC4). In gastric parietal cells, we found that ClC-5 is predominantly expressed in intracellular tubulovesicles and that KCC4 is predominantly expressed in the apical membrane. Gastric acid (HCl) secretion may be accomplished by the two different complexes of H+,K+-ATPase and Cl--transporting protein. The second topic focuses on the Na+,K+-ATPase α1-isoform (α1NaK) associated with the volume-regulated anion channel (VRAC). In the cholesterol-enriched membrane microdomains of human cancer cells, we found that α1NaK has a receptor-like (non-pumping) function and that binding of low concentrations (nM level) of cardiac glycosides to α1NaK activates VRAC and exerts anti-cancer effects without affecting the pumping function of α1NaK. The third topic is the Na+,K+-ATPase α3-isoform (α3NaK) in human cancer cells. We found that α3NaK is abnormally expressed in the intracellular vesicles of attached cancer cells and that the plasma membrane translocation of α3NaK upon cell detachment contributes to the survival of metastatic cancer cells. Our results indicate that multiple functions of P-type ion pumps are generated by different membrane environments and their associated proteins.
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Affiliation(s)
- Takuto Fujii
- Department of Pharmaceutical Physiology, Faculty of Pharmaceutical Sciences, University of Toyama
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4
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Physiological Significance of Ion Transporters and Channels in the Stomach and Pathophysiological Relevance in Gastric Cancer. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2020; 2020:2869138. [PMID: 32104192 PMCID: PMC7040404 DOI: 10.1155/2020/2869138] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 12/17/2019] [Accepted: 01/08/2020] [Indexed: 12/26/2022]
Abstract
Gastric cancer (GC) is a highly invasive and fatal malignant disease that accounts for 5.7% of new global cancer cases and is the third leading cause of cancer-related death. Acid/base homeostasis is critical for organisms because protein and enzyme function, cellular structure, and plasma membrane permeability change with pH. Various ion transporters are expressed in normal gastric mucosal epithelial cells and regulate gastric acid secretion, ion transport, and fluid absorption, thereby stabilizing the differentiation and homeostasis of gastric mucosal epithelial cells. Ion transporter dysfunction results in disordered ion transport, mucosa barrier dysfunction, and acid/base disturbances, causing gastric acid-related diseases such as chronic atrophic gastritis (CAG) and GC. This review summarizes the physiological functions of multiple ion transporters and channels in the stomach, including Cl− channels, Cl−/HCO3− exchangers, sodium/hydrogen exchangers (NHEs), and potassium (K+) channels, and their pathophysiological relevance in GC.
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5
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Baratta V, Own J, Di Renzo C, Ollodart J, Geibel JP, Barahona M. In Pursuit of the Parietal Cell - An Evolution of Scientific Methodology and Techniques. Front Physiol 2019; 10:1497. [PMID: 31920702 PMCID: PMC6920182 DOI: 10.3389/fphys.2019.01497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 11/25/2019] [Indexed: 11/30/2022] Open
Abstract
The stomach has unique embryologic and anatomic properties, making the study of the parietal cell technically challenging. Numerous individuals have devoted decades of research to unraveling the pathophysiological basis of this cell type. Here, we perform a scoping review of novel in vitro and in vivo methodology pertaining to the parietal cell. First, we evaluate early in vitro methods of parietal cell analysis. This section focuses on three major techniques: gastric gland isolation, parietal cell isolation, and parietal cell culture. We also discuss parietal cell physiology and pathophysiology. Second, we discuss more contemporary efforts involving confocal microscopy and gastric organoids, a new technique that holds much promise in unveiling the temporal-spatial dynamics of the cell. Finally, we will discuss findings from our laboratory where we identified an active gastric vacuolar H+-ATPase as a putative mechanism for refractory GERD. Overall, this review aims to highlight the major milestones in understanding an elusive yet important cell. Though in no way comprehensive, we hope to provide a birds-eye view to the study of this unique cell type in the gastrointestinal tract.
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Affiliation(s)
- Vanessa Baratta
- Department of Surgery, Yale University School of Medicine, New Haven, CT, United States
| | - Jason Own
- Department of Surgery, Yale University School of Medicine, New Haven, CT, United States
| | - Chiara Di Renzo
- Department of Surgery, Oncology and Gastroenterology, Hepatobiliary Surgery and Liver Transplantation, Padua University, Padua, Italy
| | - Jenna Ollodart
- Department of Surgery, Yale University School of Medicine, New Haven, CT, United States
| | - John P. Geibel
- Department of Surgery, Yale University School of Medicine, New Haven, CT, United States
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT, United States
| | - Maria Barahona
- Department of Surgery, Yale University School of Medicine, New Haven, CT, United States
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6
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Kitay AM, Schneebacher MT, Schmitt A, Heschl K, Kopic S, Alfadda T, Alsaihati A, Link A, Geibel JP. Modulations in extracellular calcium lead to H +-ATPase-dependent acid secretion: a clarification of PPI failure. Am J Physiol Gastrointest Liver Physiol 2018. [PMID: 29517927 DOI: 10.1152/ajpgi.00132.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The H+,K+-ATPase was identified as the primary proton secretory pathway in the gastric parietal cell and is the pharmacological target of agents suppressing acid secretion. Recently, we identified a second acid secretory protein expressed in the parietal cell, the vacuolar H+-ATPase (V-type ATPase). The aim of the present study was to further characterize H+-ATPase activation by modulations in extracellular calcium via the calcium sensing receptor (CaSR). Isolated gastric glands were loaded with the pH indicator dye BCECF-AM [2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein acetoxymethyl ester] to measure intracellular pH. Experiments were conducted in the absence of sodium and potassium to monitor H+-ATPase-specific transport activity. CaSR was activated with the calcimimetic R568 (400 nM) and/or by modulations in extracellular Ca2+. Elevation in calcium concentrations increased proton extrusion from the gastric parietal cell. Allosteric modification of the CaSR via R568 and calcium increased vacuolar H+-ATPase activity significantly (ΔpH/minlowCa2+(0.1mM) = 0.001 ± 0.001, ΔpH/minnormalCa2+(1.0mM) = 0.033 ± 0.004, ΔpH/minhighCa2+(5.0mM) = 0.051 ± 0.005). Carbachol significantly suppressed calcium-induced gastric acid secretion via the H+-ATPase under sodium- and potassium-free conditions. We conclude that the V-type H+-ATPase is tightly linked to CaSR activation. We observed that proton pump inhibitor (PPI) exposure does not modulate H+-ATPase activity. This elevated blood calcium activation of the H+-ATPase could provide an explanation for recurrent reflux symptoms while taking a PPI therapy. NEW & NOTEWORTHY This study emphasizes the role of the H+-ATPase in acid secretion. We further demonstrate the modification of this proton excretion pathway by extracellular calcium and the activation of the calcium sensing receptor CaSR. The novelty of this paper is based on the modulation of the H+-ATPase via both extracellular Ca (activation) and the classical secretagogues histamine and carbachol (inactivation). Both activation and inactivation of this proton pump are independent of PPI modulation.
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Affiliation(s)
- Alice Miriam Kitay
- Department of Surgery, Yale University School of Medicine , New Haven, Connecticut.,Department of Gastroenterology, Hepatology and Infectious Diseases, Otto-von-Guericke University, Magdeburg, Gemany
| | | | - Anne Schmitt
- Department of Surgery, Yale University School of Medicine , New Haven, Connecticut
| | - Katharina Heschl
- Department of Surgery, Yale University School of Medicine , New Haven, Connecticut
| | - Sascha Kopic
- Department of Surgery, Yale University School of Medicine , New Haven, Connecticut.,Department of Cellular and Molecular Physiology, Yale University School of Medicine , New Haven, Connecticut
| | - Tariq Alfadda
- Department of Surgery, Yale University School of Medicine , New Haven, Connecticut
| | - Abrar Alsaihati
- Department of Surgery, Yale University School of Medicine , New Haven, Connecticut
| | - Alexander Link
- Department of Gastroenterology, Hepatology and Infectious Diseases, Otto-von-Guericke University, Magdeburg, Gemany
| | - John Peter Geibel
- Department of Surgery, Yale University School of Medicine , New Haven, Connecticut.,Department of Cellular and Molecular Physiology, Yale University School of Medicine , New Haven, Connecticut
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Zopun M, Liszt KI, Stoeger V, Behrens M, Redel U, Ley JP, Hans J, Somoza V. Human Sweet Receptor T1R3 is Functional in Human Gastric Parietal Tumor Cells (HGT-1) and Modulates Cyclamate and Acesulfame K-Induced Mechanisms of Gastric Acid Secretion. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:4842-4852. [PMID: 29665689 DOI: 10.1021/acs.jafc.8b00658] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The noncaloric sweeteners (NCSs) cyclamate (Cycl) and acesulfame K (AceK) are widely added to foods and beverages. Little is known about their impact on gastric acid secretion (GAS), which is stimulated by dietary protein and bitter-tasting compounds. Since Cycl and AceK have a bitter off taste in addition to their sweet taste, we hypothesized they modulate mechanisms of GAS in human gastric parietal cells (HGT-1). HGT-1 cells were exposed to sweet tastants (50 mM of glucose, d-threonine, Cycl, or AceK) and analyzed for their intracellular pH index (IPX), as an indicator of proton secretion by means of a pH-sensitive dye, and for mRNA levels of GAS-associated genes by RT-qPCR. Since the NCSs act via the sweet taste-sensing receptor T1R2/T1R3, mRNA expression of the corresponding genes was analyzed in addition to immunocytochemical localization of the T1R2 and T1R3 receptor proteins. Exposure of HGT-1 cells to AceK or d-threonine increased the IPX to 0.60 ± 0.05 and 0.80 ± 0.04 ( P ≤ 0.05), respectively, thereby indicating a reduced secretion of protons, whereas Cycl demonstrated the opposite effect with IPX values of -0.69 ± 0.08 ( P ≤ 0.05) compared to controls (IPX = 0). Cotreatment with the T1R3-inhibitor lactisole as well as a TAS1R3 siRNA knock-down approach reduced the impact of Cycl, AceK, and d-thr on proton release ( P ≤ 0.05), whereas cotreatment with 10 mM glucose enhanced the NCS-induced effect ( P ≤ 0.05). Overall, we demonstrated Cycl and AceK as modulators of proton secretion in HGT-1 cells and identified T1R3 as a key element in this response.
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Affiliation(s)
- Muhammet Zopun
- Faculty of Chemistry, Department of Physiological Chemistry , University of Vienna , Althanstraße 14 , Vienna 1090 , Austria
| | - Kathrin I Liszt
- Faculty of Chemistry, Christian Doppler Laboratory for Bioactive Aroma Compounds , University of Vienna , Althanstraße 14 , Vienna 1090 , Austria
| | - Verena Stoeger
- Faculty of Chemistry, Christian Doppler Laboratory for Bioactive Aroma Compounds , University of Vienna , Althanstraße 14 , Vienna 1090 , Austria
| | - Maik Behrens
- Department of Molecular Genetics , German Institute of Human Nutrition Potsdam-Rehbruecke , Arthur-Scheunert-Allee , 114-116 Nuthetal , Germany
| | - Ulrike Redel
- Department of Molecular Genetics , German Institute of Human Nutrition Potsdam-Rehbruecke , Arthur-Scheunert-Allee , 114-116 Nuthetal , Germany
| | - Jakob P Ley
- Symrise AG , Mühlenfeldstraße 1 , 37603 Holzminden , Germany
| | - Joachim Hans
- Symrise AG , Mühlenfeldstraße 1 , 37603 Holzminden , Germany
| | - Veronika Somoza
- Faculty of Chemistry, Department of Physiological Chemistry , University of Vienna , Althanstraße 14 , Vienna 1090 , Austria
- Faculty of Chemistry, Christian Doppler Laboratory for Bioactive Aroma Compounds , University of Vienna , Althanstraße 14 , Vienna 1090 , Austria
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8
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Arin RM, Gorostidi A, Navarro-Imaz H, Rueda Y, Fresnedo O, Ochoa B. Adenosine: Direct and Indirect Actions on Gastric Acid Secretion. Front Physiol 2017; 8:737. [PMID: 29018360 PMCID: PMC5614973 DOI: 10.3389/fphys.2017.00737] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 09/11/2017] [Indexed: 12/12/2022] Open
Abstract
Composed by a molecule of adenine and a molecule of ribose, adenosine is a paradigm of recyclable nucleoside with a multiplicity of functions that occupies a privileged position in the metabolic and regulatory contexts. Adenosine is formed continuously in intracellular and extracellular locations of all tissues. Extracellular adenosine is a signaling molecule, able to modulate a vast range of physiologic responses in many cells and organs, including digestive organs. The adenosine A1, A2A, A2B, and A3 receptors are P1 purinergic receptors, G protein-coupled proteins implicated in tissue protection. This review is focused on gastric acid secretion, a process centered on the parietal cell of the stomach, which contains large amounts of H+/K+-ATPase, the proton pump responsible for proton extrusion during acid secretion. Gastric acid secretion is regulated by an extensive collection of neural stimuli and endocrine and paracrine agents, which act either directly at membrane receptors of the parietal cell or indirectly through other regulatory cells of the gastric mucosa, as well as mechanic and chemic stimuli. In this review, after briefly introducing these points, we condense the current body of knowledge about the modulating action of adenosine on the pathophysiology of gastric acid secretion and update its significance based on recent findings in gastric mucosa and parietal cells in humans and animal models.
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Affiliation(s)
- Rosa M Arin
- Department of Physiology, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU)Leioa, Spain
| | - Adriana Gorostidi
- Department of Physiology, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU)Leioa, Spain
| | - Hiart Navarro-Imaz
- Department of Physiology, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU)Leioa, Spain
| | - Yuri Rueda
- Department of Physiology, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU)Leioa, Spain
| | - Olatz Fresnedo
- Department of Physiology, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU)Leioa, Spain
| | - Begoña Ochoa
- Department of Physiology, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU)Leioa, Spain
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9
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Han J, Lee SH, Giebisch G, Wang T. Potassium Channelopathies and Gastrointestinal Ulceration. Gut Liver 2017; 10:881-889. [PMID: 27784845 PMCID: PMC5087926 DOI: 10.5009/gnl15414] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 10/14/2015] [Accepted: 10/20/2015] [Indexed: 12/13/2022] Open
Abstract
Potassium channels and transporters maintain potassium homeostasis and play significant roles in several different biological actions via potassium ion regulation. In previous decades, the key revelations that potassium channels and transporters are involved in the production of gastric acid and the regulation of secretion in the stomach have been recognized. Drugs used to treat peptic ulceration are often potassium transporter inhibitors. It has also been reported that potassium channels are involved in ulcerative colitis. Direct toxicity to the intestines from nonsteroidal anti-inflammatory drugs has been associated with altered potassium channel activities. Several reports have indicated that the long-term use of the antianginal drug Nicorandil, an adenosine triphosphate-sensitive potassium channel opener, increases the chances of ulceration and perforation from the oral to anal regions throughout the gastrointestinal (GI) tract. Several of these drug features provide further insights into the role of potassium channels in the occurrence of ulceration in the GI tract. The purpose of this review is to investigate whether potassium channelopathies are involved in the mechanisms responsible for ulceration that occurs throughout the GI tract.
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Affiliation(s)
- Jaeyong Han
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, USA
| | - Seung Hun Lee
- Department of Internal Medicine, Section of Nephrology, Yale University, New Haven, CT, USA
| | - Gerhard Giebisch
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, USA
| | - Tong Wang
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, USA
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10
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Kitay AM, Geibel JP. Stomach and Bone. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1033:97-131. [DOI: 10.1007/978-3-319-66653-2_6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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11
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Sakai H, Fujii T, Takeguchi N. Proton-Potassium (H+/K+) ATPases: Properties and Roles in Health and Diseases. Met Ions Life Sci 2016; 16:459-83. [DOI: 10.1007/978-3-319-21756-7_13] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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12
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Nighot MP, Nighot PK, Ma TY, Malinowska DH, Shull GE, Cuppoletti J, Blikslager AT. Genetic Ablation of the ClC-2 Cl- Channel Disrupts Mouse Gastric Parietal Cell Acid Secretion. PLoS One 2015; 10:e0138174. [PMID: 26378782 PMCID: PMC4574764 DOI: 10.1371/journal.pone.0138174] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2015] [Accepted: 08/27/2015] [Indexed: 11/30/2022] Open
Abstract
The present studies were designed to examine the effects of ClC-2 ablation on cellular morphology, parietal cell abundance, H/K ATPase expression, parietal cell ultrastructure and acid secretion using WT and ClC-2-/- mouse stomachs. Cellular histology, morphology and proteins were examined using imaging techniques, electron microscopy and western blot. The effect of histamine on the pH of gastric contents was measured. Acid secretion was also measured using methods and secretagogues previously established to give maximal acid secretion and morphological change. Compared to WT, ClC-2-/- gastric mucosal histological organization appeared disrupted, including dilation of gastric glands, shortening of the gastric gland region and disorganization of all cell layers. Parietal cell numbers and H/K ATPase expression were significantly reduced by 34% (P<0.05) and 53% (P<0.001) respectively and cytoplasmic tubulovesicles appeared markedly reduced on electron microscopic evaluation without evidence of canalicular expansion. In WT parietal cells, ClC-2 was apparent in a similar cellular location as the H/K ATPase by immunofluorescence and appeared associated with tubulovesicles by immunogold electron microscopy. Histamine-stimulated [H+] of the gastric contents was significantly (P<0.025) lower by 9.4 fold (89%) in the ClC-2-/- mouse compared to WT. Histamine/carbachol stimulated gastric acid secretion was significantly reduced (range 84–95%, P<0.005) in ClC-2-/- compared to WT, while pepsinogen secretion was unaffected. Genetic ablation of ClC-2 resulted in reduced gastric gland region, reduced parietal cell number, reduced H/K ATPase, reduced tubulovesicles and reduced stimulated acid secretion.
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Affiliation(s)
- Meghali P. Nighot
- North Carolina State University, College of Veterinary Medicine, Raleigh, North Carolina, United States of America
| | - Prashant K. Nighot
- North Carolina State University, College of Veterinary Medicine, Raleigh, North Carolina, United States of America
| | - Thomas Y. Ma
- University of New Mexico School of Medicine, Albuquerque, New Mexico, United States of America
| | - Danuta H. Malinowska
- University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Gary E. Shull
- University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - John Cuppoletti
- University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Anthony T. Blikslager
- North Carolina State University, College of Veterinary Medicine, Raleigh, North Carolina, United States of America
- * E-mail:
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13
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Fujii T, Takahashi Y, Takeshima H, Saitoh C, Shimizu T, Takeguchi N, Sakai H. Inhibition of gastric H+,K+-ATPase by 4-(2-butyl-6,7-dichloro-2-cyclopentylindan-1-on-5-yl)oxybutyric acid (DCPIB), an inhibitor of volume-regulated anion channel. Eur J Pharmacol 2015; 765:34-41. [PMID: 26277321 DOI: 10.1016/j.ejphar.2015.08.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 06/24/2015] [Accepted: 08/10/2015] [Indexed: 12/12/2022]
Abstract
4-(2-Butyl-6,7-dichloro-2-cyclopentylindan-1-on-5-yl)oxybutyric acid (DCPIB) has been used as an inhibitor of volume-regulated anion channel (VRAC), which is expressed in almost all cells (IC50 is around 4 µM). Here, we found that DCPIB significantly inhibited the activities of gastric proton pump (H+,K+-ATPase) in isolated gastric tubulovesicles and the membrane sample of the H+,K+-ATPase-expressing cells, and their IC50 values were around 9 µM. In the tubulovesicles, no significant expression of leucine rich repeat containing 8 family member A (LRRC8A), an essential component of VRAC, was observed. The inhibitory effect of DCPIB was also found in the membrane sample obtained from the cells in which LRRC8A had been knocked down. On the other hand, DCPIB had no significant effect on the activity of Na+,K+-ATPase or Ca2+-ATPase. In the H+,K+-ATPase-expressing cells, DCPIB inhibited the 86Rb+ transport activity of H+,K+-ATPase but not that of Na+,K+-ATPase. DCPIB had no effect on the activity of Cl- channels other than VRAC in the cells. These results suggest that DCPIB directly inhibits H+,K+-ATPase activity. DCPIB may be a beneficial tool for studying the H+,K+-ATPase function in vitro.
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Affiliation(s)
- Takuto Fujii
- Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Yuji Takahashi
- Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Hiroshi Takeshima
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Chisato Saitoh
- Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Takahiro Shimizu
- Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Noriaki Takeguchi
- Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Hideki Sakai
- Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
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14
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Digestive system dysfunction in cystic fibrosis: challenges for nutrition therapy. Dig Liver Dis 2014; 46:865-74. [PMID: 25053610 DOI: 10.1016/j.dld.2014.06.011] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 06/10/2014] [Accepted: 06/28/2014] [Indexed: 02/08/2023]
Abstract
Cystic fibrosis can affect food digestion and nutrient absorption. The underlying mutation of the cystic fibrosis trans-membrane regulator gene depletes functional cystic fibrosis trans-membrane regulator on the surface of epithelial cells lining the digestive tract and associated organs, where Cl(-) secretion and subsequently secretion of water and other ions are impaired. This alters pH and dehydrates secretions that precipitate and obstruct the lumen, causing inflammation and the eventual degradation of the pancreas, liver, gallbladder and intestine. Associated conditions include exocrine pancreatic insufficiency, impaired bicarbonate and bile acid secretion and aberrant mucus formation, commonly leading to maldigestion and malabsorption, particularly of fat and fat-soluble vitamins. Pancreatic enzyme replacement therapy is used to address this insufficiency. The susceptibility of pancreatic lipase to acidic and enzymatic inactivation and decreased bile availability often impedes its efficacy. Brush border digestive enzyme activity and intestinal uptake of certain disaccharides and amino acids await clarification. Other complications that may contribute to maldigestion/malabsorption include small intestine bacterial overgrowth, enteric circular muscle dysfunction, abnormal intestinal mucus, and intestinal inflammation. However, there is some evidence that gastric digestive enzymes, colonic microflora, correction of fatty acid abnormalities using dietary n-3 polyunsaturated fatty acid supplementation and emerging intestinal biomarkers can complement nutrition management in cystic fibrosis.
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Takahashi Y, Fujii T, Fujita K, Shimizu T, Higuchi T, Tabuchi Y, Sakamoto H, Naito I, Manabe K, Uchida S, Sasaki S, Ikari A, Tsukada K, Sakai H. Functional coupling of chloride-proton exchanger ClC-5 to gastric H+,K+-ATPase. Biol Open 2014; 3:12-21. [PMID: 24429108 PMCID: PMC3892156 DOI: 10.1242/bio.20136205] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
It has been reported that chloride–proton exchanger ClC-5 and vacuolar-type H+-ATPase are essential for endosomal acidification in the renal proximal cells. Here, we found that ClC-5 is expressed in the gastric parietal cells which secrete actively hydrochloric acid at the luminal region of the gland, and that it is partially localized in the intracellular tubulovesicles in which gastric H+,K+-ATPase is abundantly expressed. ClC-5 was co-immunoprecipitated with H+,K+-ATPase in the lysate of tubulovesicles. The ATP-dependent uptake of 36Cl− into the vesicles was abolished by 2-methyl-8-(phenylmethoxy)imidazo[1,2-a]pyridine-3-acetonitrile (SCH28080), an inhibitor of H+,K+-ATPase, suggesting functional expression of ClC-5. In the tetracycline-regulated expression system of ClC-5 in the HEK293 cells stably expressing gastric H+,K+-ATPase, ClC-5 was co-immunoprecipitated with H+,K+-ATPase, but not with endogenous Na+,K+-ATPase. The SCH28080-sensitive 36Cl− transporting activity was observed in the ClC-5-expressing cells, but not in the ClC-5-non-expressing cells. The mutant (E211A-ClC-5), which has no H+ transport activity, did not show the SCH28080-sensitive 36Cl− transport. On the other hand, both ClC-5 and its mutant (E211A) significantly increased the activity of H+,K+-ATPase. Our results suggest that ClC-5 and H+,K+-ATPase are functionally associated and that they may contribute to gastric acid secretion.
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Affiliation(s)
- Yuji Takahashi
- Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan
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16
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Fisher JT, Tyler SR, Zhang Y, Lee BJ, Liu X, Sun X, Sui H, Liang B, Luo M, Xie W, Yi Y, Zhou W, Song Y, Keiser N, Wang K, de Jonge HR, Engelhardt JF. Bioelectric characterization of epithelia from neonatal CFTR knockout ferrets. Am J Respir Cell Mol Biol 2013; 49:837-44. [PMID: 23782101 DOI: 10.1165/rcmb.2012-0433oc] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Cystic fibrosis (CF) is a life-shortening, recessive, multiorgan genetic disorder caused by the loss of CF transmembrane conductance regulator (CFTR) chloride channel function found in many types of epithelia. Animal models that recapitulate the human disease phenotype are critical to understanding pathophysiology in CF and developing therapies. CFTR knockout ferrets manifest many of the phenotypes observed in the human disease, including lung infections, pancreatic disease and diabetes, liver disease, malnutrition, and meconium ileus. In the present study, we have characterized abnormalities in the bioelectric properties of the trachea, stomach, intestine, and gallbladder of newborn CF ferrets. Short-circuit current (ISC) analysis of CF and wild-type (WT) tracheas revealed the following similarities and differences: (1) amiloride-sensitive sodium currents were similar between genotypes; (2) responses to 4,4'-diisothiocyano-2,2'-stilbene disulphonic acid were 3.3-fold greater in CF animals, suggesting elevated baseline chloride transport through non-CFTR channels in a subset of CF animals; and (3) a lack of 3-isobutyl-1-methylxanthine (IBMX)/forskolin-stimulated and N-(2-Naphthalenyl)-((3,5-dibromo-2,4-dihydroxyphenyl)methylene)glycine hydrazide (GlyH-101)-inhibited currents in CF animals due to the lack of CFTR. CFTR mRNA was present throughout all levels of the WT ferret and IBMX/forskolin-inducible ISC was only observed in WT animals. However, despite the lack of CFTR function in the knockout ferret, the luminal pH of the CF ferret gallbladder, stomach, and intestines was not significantly changed relative to WT. The WT stomach and gallbladder exhibited significantly enhanced IBMX/forskolin ISC responses and inhibition by GlyH-101 relative to CF samples. These findings demonstrate that multiple organs affected by disease in the CF ferret have bioelectric abnormalities consistent with the lack of cAMP-mediated chloride transport.
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Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) protein is highly expressed in the pancreatic duct epithelia and permits anions and water to enter the ductal lumen. This results in an increased volume of alkaline fluid allowing the highly concentrated proteins secreted by the acinar cells to remain in a soluble state. This work will expound on the pathophysiology and pathology caused by the malfunctioning CFTR protein with special reference to ion transport and acid-base abnormalities both in humans and animal models. We will also discuss the relationship between cystic fibrosis (CF) and pancreatitis, and outline present and potential therapeutic approaches in CF treatment relevant to the pancreas.
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Affiliation(s)
- Michael Wilschanski
- Pediatric Gastroenterology, Hadassah University Hospital, Jerusalem 91240, Israel
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18
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Kopic S, Geibel JP. Gastric acid, calcium absorption, and their impact on bone health. Physiol Rev 2013; 93:189-268. [PMID: 23303909 DOI: 10.1152/physrev.00015.2012] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Calcium balance is essential for a multitude of physiological processes, ranging from cell signaling to maintenance of bone health. Adequate intestinal absorption of calcium is a major factor for maintaining systemic calcium homeostasis. Recent observations indicate that a reduction of gastric acidity may impair effective calcium uptake through the intestine. This article reviews the physiology of gastric acid secretion, intestinal calcium absorption, and their respective neuroendocrine regulation and explores the physiological basis of a potential link between these individual systems.
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Affiliation(s)
- Sascha Kopic
- Department of Surgery and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut, USA
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19
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Atteinte digestive (pancréatique et intestinale) de la mucoviscidose : approche physiopathologique. Arch Pediatr 2012; 19 Suppl 1:S20-2. [DOI: 10.1016/s0929-693x(12)71103-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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20
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21
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Shenoy A, Kopic S, Murek M, Caputo C, Geibel JP, Egan ME. Calcium-modulated chloride pathways contribute to chloride flux in murine cystic fibrosis-affected macrophages. Pediatr Res 2011; 70:447-52. [PMID: 21796019 PMCID: PMC3189336 DOI: 10.1203/pdr.0b013e31822f2448] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Cystic fibrosis (CF), a common lethal inherited disorder defined by ion transport abnormalities, chronic infection, and robust inflammation, is the result of mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein, a cAMP-activated chloride (Cl-) channel. Macrophages are reported to have impaired activity in CF. Previous studies suggest that Cl- transport is important for macrophage function; therefore, impaired Cl- secretion may underlie CF macrophage dysfunction. To determine whether alterations in Cl- transport exist in CF macrophages, Cl- efflux was measured using N-[ethoxycarbonylmethyl]- 6-methoxy-quinolinium bromide (MQAE), a fluorescent indicator dye. The contribution of CFTR was assessed by calculating Cl- flux in the presence and absence of cftr(inh)-172. The contribution of calcium (Ca(2+))-modulated Cl- pathways was assessed by examining Cl- flux with varied extracellular Ca(2+) concentrations or after treatment with carbachol or thapsigargin, agents that increase intracellular Ca(2+) levels. Our data demonstrate that CFTR contributed to Cl- efflux only in WT macrophages, while Ca(2+)-mediated pathways contributed to Cl- transport in CF and WT macrophages. Furthermore, CF macrophages demonstrated augmented Cl- efflux with increases in extracellular Ca(2+). Taken together, this suggests that Ca(2+)-mediated Cl- pathways are enhanced in CF macrophages compared with WT macrophages.
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Affiliation(s)
- Ambika Shenoy
- Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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22
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Fujii T, Fujita K, Takeguchi N, Sakai H. Function of K⁺-Cl⁻ cotransporters in the acid secretory mechanism of gastric parietal cells. Biol Pharm Bull 2011; 34:810-2. [PMID: 21628876 DOI: 10.1248/bpb.34.810] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Gastric proton pump (H⁺, K⁺-ATPase) secretes H⁺ of acid (HCl) via the luminal membrane of parietal cells. For the HCl secretion, Cl⁻- and K⁺-transporting proteins are required. Recent our studies have demonstrated that K⁺-Cl⁻ cotransporters (KCC3a and KCC4) are expressed in gastric parietal cells. KCC3a is associated with Na⁺, K⁺-ATPase in the basolateral membrane, and KCC4 is associated with H⁺, K⁺-ATPase in the apical canalicular membrane. This paper summarizes the functional association between KCCs and P-type ATPases and the contribution of these complexes to acid secretion in gastric parietal cells.
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Affiliation(s)
- Takuto Fujii
- Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan.
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23
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Aoyama F, Sawaguchi A. Functional transformation of gastric parietal cells and intracellular trafficking of ion channels/transporters in the apical canalicular membrane associated with acid secretion. Biol Pharm Bull 2011; 34:813-6. [PMID: 21628877 DOI: 10.1248/bpb.34.813] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The parietal cell of the gastric gland is a highly differentiated cell responsible for the gastric hydrochloric acid secretion into the lumen of the stomach. In response to stimulation of acid secretion, the parietal cells undergo well-characterized morphological transformations to recruit H⁺/K⁺-ATPase from the cytoplasmic tubulovesicles to the apical canalicular membrane. Besides H⁺ extrusion via H⁺/K⁺-ATPase, Cl⁻ efflux and K⁺ recycling across the apical canalicular membrane are necessary via chloride and potassium channels/transporters, respectively. In the last decade, a number of molecular candidates for the Cl⁻ efflux and K⁺ recycling have been identified in the apical canalicular membrane of the parietal cell. This review focuses on the functional transformation of gastric parietal cells and intracellular trafficking of ion channels/transporters expressed in the apical canalicular membrane associated with gastric acid secretion.
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Affiliation(s)
- Fumiyo Aoyama
- Department of Anatomy, Ultrastructural Cell Biology, Faculty of Medicine, University of Miyazaki, Kiyotake, Miyazaki, Japan
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24
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Fujii T, Morii M, Takeguchi N, Sakai H. [Molecular mechanisms of H(+) and Cl(-) secretion in gastric parietal cells]. Nihon Yakurigaku Zasshi 2011; 138:51-5. [PMID: 21828937 DOI: 10.1254/fpj.138.51] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Rotte A, Pasham V, Mack AF, Bhandaru M, Qadri SM, Eichenmüller M, Ruth P, Lang F. Ca2+ activated K+ channel Kca3.1 as a determinant of gastric acid secretion. Cell Physiol Biochem 2011; 27:597-604. [PMID: 21691077 DOI: 10.1159/000329981] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/28/2011] [Indexed: 12/28/2022] Open
Abstract
The Ca(2+) activated K(+) channel K(ca)3.1 is expressed in a variety of tissues. In the gastric gland it is expressed in the basolateral cell membrane. To determine the functional significance of K(ca)3.1 activity for gastric acid secretion, gastric acid secretion was determined in isolated glands from gene targeted mice lacking functional K(ca)3.1 (K(ca)3.1(-/-)) and from their wild type littermates (K(ca)3.1(+/+)). According to BCECF-fluorescence cytosolic pH in isolated gastric glands was similar in K(ca)3.1(-/-) and K(ca)3.1(+/+) mice. Na(ca)-independent pH recovery (ΔpH/min) following an ammonium pulse, a measure of H(ca)/K(ca) ATPase activity, was, however, significantly faster in K(ca)3.1(-/-) than in K(ca)3.1(+/+) mice. Accordingly, the luminal pH was significantly lower and the acid content significantly higher in K(ca)3.1(-/-) than in K(ca)3.1(+/+) mice. The abundance of mRNA encoding H(ca)/K(ca) ATPase and KCNQ1 was similar in both genotypes. Increase of extracellular K(ca) concentrations to 35 mM (replacing Na(ca)/NMDG) and treatment with histamine (100 μM) significantly increased ΔpH/min to a larger extent in K(ca)3.1(+/+) than in K(ca)3.1(-/-) mice and dissipated the differences between the genotypes. Carbachol (100 μM) increased ΔpH/min in both genotypes but did not abolish the difference between K(ca)3.1(-/-) and K(ca)3.1(+/+) mice. In K(ca)3.1(+/+) mice the K(ca)3.1 opener DCEBIO (100 μM) did not significantly alter basal ΔpH/min but significantly blunted ΔpH/min in the presence of carbachol. In conclusion, K(ca)3.1 activity suppresses carbachol stimulated gastric acid secretion.
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Affiliation(s)
- Anand Rotte
- Department of Physiology, University of Tübingen, Gmelinstrasse 5, Tübingen, Germany
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26
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Pasham V, Rotte A, Bhandaru M, Eichenmüller M, Bobbala D, Yang W, Pearce D, Lang F, Pearce D, Lang F. Regulation of gastric acid secretion by the serum and glucocorticoid inducible kinase isoform SGK3. J Gastroenterol 2011; 46:305-17. [PMID: 21113728 PMCID: PMC6049078 DOI: 10.1007/s00535-010-0348-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Accepted: 10/26/2010] [Indexed: 02/04/2023]
Abstract
BACKGROUND The serum and glucocorticoid inducible kinase isoform SGK3 is ubiquitously expressed and has been shown to participate in the regulation of cell survival and transport. Similar to SGK1 and protein kinase B (PKB/Akt) isoforms, SGK3 may phosphorylate glycogen synthase kinase (GSK) 3α,β, which has recently been shown to participate in the regulation of basal gastric acid secretion. The present study thus explored the role of SGK3 in the regulation of gastric acid secretion. METHODS Experiments were performed in isolated glands from gene-targeted mice lacking functional SGK3 (sgk3-/-) or from their wild-type littermates (sgk3+/+). Utilizing 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein, acetoxymethyl ester (BCECF) fluorescence, gastric acid secretion was determined from Na(+)-independent pH recovery (∆pH/min) following an ammonium pulse, which reflects H+/K+ adenosine triphosphatase (ATP) ase activity. RESULTS Cytosolic pH in isolated gastric glands was similar in sgk3-/- and sgk3+/+ mice. ∆pH/min was, however, significantly larger in sgk3-/- than in sgk3+/+ mice. In both genotypes, ∆pH/min was virtually abolished in the presence of the H(+)/K(+) ATPase inhibitor omeprazole (100 μM) and SCH28080 (500 nM). Increase of extracellular K+ concentrations to 35 mM (replacing Na+/NMDG) or treatment with 5 μM forskolin increased ∆pH/min in sgk3+/+ mice to a larger extent than in sgk3-/- mice and abrogated the differences between genotypes. The protein kinase A inhibitor H89 (150 nM) decreased ∆pH/min to similarly low values in both genotypes. CONCLUSIONS SGK3 suppresses gastric acid secretion, an effect presumably mediated by the stimulation of protein kinase A with the subsequent activation of K+ channels.
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Affiliation(s)
| | - Anand Rotte
- Department of Physiology, University of Tübingen, Germany
| | | | | | | | - Wenting Yang
- Department of Physiology, University of Tübingen, Germany
| | - David Pearce
- Department of Medicine (Nephrology), University of California, San Francisco, CA 94122, USA
| | - Florian Lang
- Department of Physiology, University of Tübingen, Germany
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Abstract
Acid-related disorders represent a major healthcare concern. In recent years, our understanding of the physiologic processes underlying gastric acid secretion has improved notably. The identity of several apical ion transport proteins, which are necessary for acid secretion to take place, has been resolved. The recent developments have uncovered potential therapeutic targets for the treatment of acid-related disorders. This brief review provides an update on the mechanisms of gastric acid secretion, with a particular focus on apical ion transport.
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Affiliation(s)
- Sascha Kopic
- Departments of Surgery and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT, USA
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28
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Rotte A, Pasham V, Bhandaru M, Eichenmüller M, Yang W, Qadri SM, Kempe DS, Puchchakayala G, Pearce D, Birnbaum MJ, Lang F. Regulation of gastric acid secretion by PKB/Akt2. Cell Physiol Biochem 2010; 25:695-704. [PMID: 20511715 DOI: 10.1159/000315089] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/08/2010] [Indexed: 12/16/2022] Open
Abstract
Pharmacological inhibition of phosphoinositol 3 kinase (PI3K) and partial deficiency of phosphoinositide dependent kinase PDK1 have previously been shown to enhance basal gastric acid secretion. PI3K/PDK1 dependent signaling involves activation of protein kinase B/Akt, which may thus be similarly involved in the regulation of gastric acid secretion. To test that hypothesis, gastric acid secretion was determined in isolated glands from gene targeted mice lacking functional Akt2 (akt2(-/-)) or from their wild type littermates (akt2(+/+)). According to BCECF-fluorescence cytosolic pH in isolated gastric glands was similar in akt2(-/-) and akt2(+/+) mice. Na(+)-independent pH recovery (DeltapH/min) following an ammonium pulse, a measure of H(+)/K(+) ATPase activity, was, however, significantly faster in akt2(-/-) than in akt2(+/+) mice. In both genotypes, DeltapH/min was virtually abolished by H(+)/K(+) ATPase inhibitor omeprazole (100 muM). Increase of extracellular K(+) concentrations to 35 mM (replacing Na(+)) increased DeltapH/min to a significantly larger extent in akt2(+/+) than in akt2(-/-) mice and dissipated the differences between the genotypes. Similarly, treatment with 5 muM forskolin enhanced DeltapH/min significantly only in akt2(+/+) mice and abolished the differences between the genotypes. Conversely, protein kinase A inhibitor H89 (50 nM) decreased DeltapH/min to similarly low values in both genotypes. In conclusion, Akt2 suppresses gastric acid secretion and contributes to or even accounts for the inhibition of gastric acid secretion by PI3K.
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Affiliation(s)
- Anand Rotte
- Department of Physiology, University of Tübingen, D-72076 Tübingen, Germany
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29
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Abstract
The parietal cell is responsible for secreting concentrated hydrochloric acid into the gastric lumen. To fulfill this task, it is equipped with a broad variety of functionally coupled apical and basolateral ion transport proteins. The concerted scientific effort over the last years by a variety of researchers has provided us with the molecular identity of many of these transport mechanisms, thereby contributing to the clarification of persistent controversies in the field. This article will briefly review the current model of parietal cell physiology and ion transport in particular and will update the existing models of apical and basolateral transport in the parietal cell.
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Affiliation(s)
- Sascha Kopic
- Department of Surgery, Yale University, School of Medicine, New Haven, Connecticut
| | - Michael Murek
- Department of Surgery, Yale University, School of Medicine, New Haven, Connecticut
| | - John P. Geibel
- Department of Surgery, Yale University, School of Medicine, New Haven, Connecticut
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30
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AMP-activated protein kinase: a physiological off switch for murine gastric acid secretion. Pflugers Arch 2009; 459:39-46. [DOI: 10.1007/s00424-009-0698-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Revised: 06/11/2009] [Accepted: 06/30/2009] [Indexed: 10/20/2022]
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31
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Fujii T, Takahashi Y, Ikari A, Morii M, Tabuchi Y, Tsukada K, Takeguchi N, Sakai H. Functional Association between K+-Cl- Cotransporter-4 and H+,K+-ATPase in the Apical Canalicular Membrane of Gastric Parietal Cells. J Biol Chem 2009; 284:619-629. [DOI: 10.1074/jbc.m806562200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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32
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Heitzmann D, Warth R. Physiology and pathophysiology of potassium channels in gastrointestinal epithelia. Physiol Rev 2008; 88:1119-82. [PMID: 18626068 DOI: 10.1152/physrev.00020.2007] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Epithelial cells of the gastrointestinal tract are an important barrier between the "milieu interne" and the luminal content of the gut. They perform transport of nutrients, salts, and water, which is essential for the maintenance of body homeostasis. In these epithelia, a variety of K(+) channels are expressed, allowing adaptation to different needs. This review provides an overview of the current literature that has led to a better understanding of the multifaceted function of gastrointestinal K(+) channels, thereby shedding light on pathophysiological implications of impaired channel function. For instance, in gastric mucosa, K(+) channel function is a prerequisite for acid secretion of parietal cells. In epithelial cells of small intestine, K(+) channels provide the driving force for electrogenic transport processes across the plasma membrane, and they are involved in cell volume regulation. Fine tuning of salt and water transport and of K(+) homeostasis occurs in colonic epithelia cells, where K(+) channels are involved in secretory and reabsorptive processes. Furthermore, there is growing evidence for changes in epithelial K(+) channel expression during cell proliferation, differentiation, apoptosis, and, under pathological conditions, carcinogenesis. In the future, integrative approaches using functional and postgenomic/proteomic techniques will help us to gain comprehensive insights into the role of K(+) channels of the gastrointestinal tract.
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Affiliation(s)
- Dirk Heitzmann
- Institute of Physiology and Clinic and Policlinic for Internal Medicine II, Regensburg, Germany
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33
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Schubert ML, Peura DA. Control of gastric acid secretion in health and disease. Gastroenterology 2008; 134:1842-60. [PMID: 18474247 DOI: 10.1053/j.gastro.2008.05.021] [Citation(s) in RCA: 254] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Accepted: 04/28/2008] [Indexed: 12/16/2022]
Abstract
Recent milestones in the understanding of gastric acid secretion and treatment of acid-peptic disorders include the (1) discovery of histamine H(2)-receptors and development of histamine H(2)-receptor antagonists, (2) identification of H(+)K(+)-ATPase as the parietal cell proton pump and development of proton pump inhibitors, and (3) identification of Helicobacter pylori as the major cause of duodenal ulcer and development of effective eradication regimens. This review emphasizes the importance and relevance of gastric acid secretion and its regulation in health and disease. We review the physiology and pathophysiology of acid secretion as well as evidence regarding its inhibition in the management of acid-related clinical conditions.
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Affiliation(s)
- Mitchell L Schubert
- Department of Medicine, Division of Gastroenterology, Virginia Commonwealth University's Medical College of Virginia, McGuire Veterans Affairs Medical Center, Richmond, Virginia 23249, USA.
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34
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Heitzmann D, Warth R. No potassium, no acid: K+ channels and gastric acid secretion. Physiology (Bethesda) 2008; 22:335-41. [PMID: 17928547 DOI: 10.1152/physiol.00016.2007] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The gastric H+-K+-ATPase pumps H+ into the lumen and takes up K+ in parallel. In the acid-producing parietal cells, luminal KCNE2/KCNQ1 K+ channels play a pivotal role in replenishing K+ in the luminal fluid. Inactivation of KCNE2/KCNQ1 channels abrogates gastric acid secretion and dramatically modifies the architecture of gastric mucosa.
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35
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Abstract
PURPOSE OF REVIEW This review summarizes the past year's literature regarding the regulation of gastric exocrine and endocrine secretion. RECENT FINDINGS Gastric acid secretion is tightly regulated by overlapping neural, hormonal, paracrine, and intracellular pathways in order to achieve the correct amount of acid secretion required by the specific situation. Too little acid can interfere with the absorption of iron, calcium, vitamin B12, and certain drugs as well as predispose to enteric infection, bacterial overgrowth, and gastric malignancy. Too much acid can induce esophageal, gastric, and duodenal injury. Gastrin, histamine, acetylcholine, and ghrelin stimulate whereas somatostatin, cholecystokinin, atrial natriuretic peptide, and nitric oxide inhibit acid secretion. Most patients infected with Helicobacter pylori manifest a pangastritis and produce less than normal amounts of acid; those with antral predominant gastritis, however, are hypergastrinemic and produce increased amounts of acid. Improved understanding of the channels and receptors that are required for and regulate H+K+-ATPase activity should lead to the development of novel antisecretory agents. SUMMARY A better understanding of the pathways regulating gastric secretions should lead to new strategies to prevent and treat a variety of gastric disorders such as gastroesophageal reflux disease, autoimmune gastritis, gastric cancer, and functional dyspepsia.
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Affiliation(s)
- Mitchell L Schubert
- Department of Medicine, Division of Gastroenterology, Virginia Commonwealth University's Medical College of Virginia and McGuire Veterans Affairs Medical Center, Richmond, Virginia 23249, USA.
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