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Imazato H, Takahashi N, Hirakawa Y, Yamaguchi Y, Hiyoshi M, Tajima T, Chosa E, Sawaguchi A. Three-dimensional fine structures in deep fascia revealed by combined use of cryo-fixed histochemistry and low-vacuum scanning microscopy. Sci Rep 2023; 13:6352. [PMID: 37072465 PMCID: PMC10113183 DOI: 10.1038/s41598-023-33479-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 04/13/2023] [Indexed: 05/03/2023] Open
Abstract
Recent physiological studies have shown that the deep fascia has received much attention concerning clinical medicine; however, histological examination of the deep fascia has not been well established. In this study, we aimed to clarify and visualize the structure of the deep fascia by taking advantage of cryofixation techniques and low-vacuum scanning electron microscopy. As a result, the ultrastructural observations revealed three-dimensional stratification of the deep fascia composed of three layers: the first superficial layer consisting of collagen fibers extending in various directions with blood vessels and peripheral nerves; the second intermediate layer formed by single straight and thick collagen fibers with flexibility; and the third deepest layer, consisting of relatively straight and thin collagen fibers. We explored the use of two hooks to hold a piece of deep fascia in place through the course of cryo-fixation. A comparative observation with or without the hook-holding procedure would indicate the morphological adaptation to physiological stretch and contraction of the deep fascia. The present morphological approach paves the way to visualize three-dimensional ultrastructures for future biomedical studies including clinical pathophysiology.
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Affiliation(s)
- Hiroyuki Imazato
- Division of Orthopaedic Surgery, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki, 889-1692, Japan
| | - Nobuyasu Takahashi
- Department of Anatomy, Ultrastructural Cell Biology, Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692, Japan.
| | - Yusuke Hirakawa
- Division of Orthopaedic Surgery, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki, 889-1692, Japan
| | - Yoichiro Yamaguchi
- Division of Orthopaedic Surgery, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki, 889-1692, Japan
| | - Masaru Hiyoshi
- Division of Orthopaedic Surgery, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki, 889-1692, Japan
| | - Takuya Tajima
- Division of Orthopaedic Surgery, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki, 889-1692, Japan
| | - Etsuo Chosa
- Division of Orthopaedic Surgery, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki, 889-1692, Japan
| | - Akira Sawaguchi
- Department of Anatomy, Ultrastructural Cell Biology, Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692, Japan
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Sawaguchi A, Kamimura T, Takahashi N, Yamashita A, Asada Y, Imazato H, Aoyama F, Wakui A, Sato T, Choijookhuu N, Hishikawa Y. In situ strategy for biomedical target localization via nanogold nucleation and secondary growth. Commun Biol 2021; 4:710. [PMID: 34112923 PMCID: PMC8192519 DOI: 10.1038/s42003-021-02246-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 05/19/2021] [Indexed: 01/20/2023] Open
Abstract
Immunocytochemistry visualizes the exact spatial location of target molecules. The most common strategy for ultrastructural immunocytochemistry is the conjugation of nanogold particles to antibodies as probes. However, conventional nanogold labelling requires time-consuming nanogold probe preparation and ultrathin sectioning of cell/tissue samples. Here, we introduce an in situ strategy involving nanogold nucleation in immunoenzymatic products on universal paraffin/cryostat sections and provide unique insight into nanogold development under hot-humid air conditions. Nanogold particles were specifically localized on kidney podocytes to target synaptopodin. Transmission electron microscopy revealed secondary growth and self-assembly that could be experimentally controlled by bovine serum albumin stabilization and phosphate-buffered saline acceleration. Valuable retrospective nanogold labelling for gastric H+/K+-ATPase was achieved on vintage immunoenzymatic deposits after a long lapse of 15 years (i.e., 15-year-old deposits). The present in situ nanogold labelling is anticipated to fill the gap between light and electron microscopy to correlate cell/tissue structure and function.
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Affiliation(s)
- Akira Sawaguchi
- Division of Ultrastructural Cell Biology, Department of Anatomy, University of Miyazaki, Miyazaki, Japan.
| | | | - Nobuyasu Takahashi
- Division of Ultrastructural Cell Biology, Department of Anatomy, University of Miyazaki, Miyazaki, Japan
| | - Atsushi Yamashita
- Division of Pathophysiology, Department of Pathology, University of Miyazaki, Miyazaki, Japan
| | - Yujiro Asada
- Division of Pathophysiology, Department of Pathology, University of Miyazaki, Miyazaki, Japan
| | - Hiroyuki Imazato
- Division of Orthopedic Surgery, Department of Medicine of Sensory and Motor Organs, University of Miyazaki, Miyazaki, Japan
| | - Fumiyo Aoyama
- Division of Ultrastructural Cell Biology, Department of Anatomy, University of Miyazaki, Miyazaki, Japan
| | | | | | - Narantsog Choijookhuu
- Division of Histochemical Cell Biology, Department of Anatomy, University of Miyazaki, Miyazaki, Japan
| | - Yoshitaka Hishikawa
- Division of Histochemical Cell Biology, Department of Anatomy, University of Miyazaki, Miyazaki, Japan
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Engevik AC, Kaji I, Goldenring JR. The Physiology of the Gastric Parietal Cell. Physiol Rev 2020; 100:573-602. [PMID: 31670611 PMCID: PMC7327232 DOI: 10.1152/physrev.00016.2019] [Citation(s) in RCA: 101] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 10/10/2019] [Accepted: 10/13/2019] [Indexed: 12/11/2022] Open
Abstract
Parietal cells are responsible for gastric acid secretion, which aids in the digestion of food, absorption of minerals, and control of harmful bacteria. However, a fine balance of activators and inhibitors of parietal cell-mediated acid secretion is required to ensure proper digestion of food, while preventing damage to the gastric and duodenal mucosa. As a result, parietal cell secretion is highly regulated through numerous mechanisms including the vagus nerve, gastrin, histamine, ghrelin, somatostatin, glucagon-like peptide 1, and other agonists and antagonists. The tight regulation of parietal cells ensures the proper secretion of HCl. The H+-K+-ATPase enzyme expressed in parietal cells regulates the exchange of cytoplasmic H+ for extracellular K+. The H+ secreted into the gastric lumen by the H+-K+-ATPase combines with luminal Cl- to form gastric acid, HCl. Inhibition of the H+-K+-ATPase is the most efficacious method of preventing harmful gastric acid secretion. Proton pump inhibitors and potassium competitive acid blockers are widely used therapeutically to inhibit acid secretion. Stimulated delivery of the H+-K+-ATPase to the parietal cell apical surface requires the fusion of intracellular tubulovesicles with the overlying secretory canaliculus, a process that represents the most prominent example of apical membrane recycling. In addition to their unique ability to secrete gastric acid, parietal cells also play an important role in gastric mucosal homeostasis through the secretion of multiple growth factor molecules. The gastric parietal cell therefore plays multiple roles in gastric secretion and protection as well as coordination of physiological repair.
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Affiliation(s)
- Amy C Engevik
- Departments of Surgery and of Cell and Developmental Biology and the Epithelial Biology Center, Vanderbilt University School of Medicine, Vanderbilt University Medical Center and the Nashville VA Medical Center, Nashville, Tennessee
| | - Izumi Kaji
- Departments of Surgery and of Cell and Developmental Biology and the Epithelial Biology Center, Vanderbilt University School of Medicine, Vanderbilt University Medical Center and the Nashville VA Medical Center, Nashville, Tennessee
| | - James R Goldenring
- Departments of Surgery and of Cell and Developmental Biology and the Epithelial Biology Center, Vanderbilt University School of Medicine, Vanderbilt University Medical Center and the Nashville VA Medical Center, Nashville, Tennessee
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Nishi M, Aoyama F, Kisa F, Zhu H, Sun M, Lin P, Ohta H, Van B, Yamamoto S, Kakizawa S, Sakai H, Ma J, Sawaguchi A, Takeshima H. TRIM50 protein regulates vesicular trafficking for acid secretion in gastric parietal cells. J Biol Chem 2012; 287:33523-32. [PMID: 22872646 DOI: 10.1074/jbc.m112.370551] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Of the TRIM/RBCC family proteins taking part in a variety of cellular processes, TRIM50 is a stomach-specific member with no defined biological function. Our biochemical data demonstrated that TRIM50 is specifically expressed in gastric parietal cells and is predominantly localized in the tubulovesicular and canalicular membranes. In cultured cells ectopically expressing GFP-TRIM50, confocal microscopic imaging revealed dynamic movement of TRIM50-associated vesicles in a phosphoinositide 3-kinase-dependent manner. A protein overlay assay detected preferential binding of the PRY-SPRY domain from the TRIM50 C-terminal region to phosphatidylinositol species, suggesting that TRIM50 is involved in vesicular dynamics by sensing the phosphorylated state of phosphoinositol lipids. Trim50 knock-out mice retained normal histology in the gastric mucosa but exhibited impaired secretion of gastric acid. In response to histamine, Trim50 knock-out parietal cells generated deranged canaliculi, swollen microvilli lacking actin filaments, and excess multilamellar membrane complexes. Therefore, TRIM50 seems to play an essential role in tubulovesicular dynamics, promoting the formation of sophisticated canaliculi and microvilli during acid secretion in parietal cells.
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Affiliation(s)
- Miyuki Nishi
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
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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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Chandra M, Zhou H, Li Q, Muallem S, Hofmann SL, Soyombo AA. A role for the Ca2+ channel TRPML1 in gastric acid secretion, based on analysis of knockout mice. Gastroenterology 2011; 140:857-67. [PMID: 21111738 PMCID: PMC3057336 DOI: 10.1053/j.gastro.2010.11.040] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Revised: 11/03/2010] [Accepted: 11/10/2010] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS Mutations in TRPML1, a lysosomal Ca(2+)-permeable TRP channel, lead to mucolipidosis type IV, a neurodegenerative lysosomal storage disease. An unusual feature of mucolipidosis type IV is constitutive achlorhydria. We produced Trpml1(-/-) (null) mice to investigate the requirement for this protein in gastric acid secretion. METHODS Trpml1-null mice were generated by gene targeting. The expression of Trpml1 and its role in acid secretion by gastric parietal cells were analyzed using biochemical, histologic, and ultrastructural approaches. RESULTS Trpml1 is expressed by parietal cells and localizes predominantly to the lysosomes; it was dynamically palmitoylated and dephosphorylated in vivo following histamine stimulation of acid secretion. Trpml1-null mice had significant impairments in basal and histamine-stimulated gastric acid secretion and markedly reduced levels of the gastric proton pump. Histologic and ultrastructural analyses revealed that Trpml1(-/-) parietal cells were enlarged, had multivesicular and multi-lamellated lysosomes, and maintained an abnormal intracellular canalicular membrane. The intralysosomal Ca(2+) content and receptor-mediated Ca(2+) signaling were, however, unaffected in Trpml1(-/-) gastric glands, indicating that Trpml1 does not function in the regulation of lysosomal Ca(2+). CONCLUSIONS Loss of Trpml1 causes reduced levels and mislocalization of the gastric proton pump and alters the secretory canaliculi, causing hypochlorhydria and hypergastrinemia. The lysosomal enlargement and defective intracellular canaliculi formation observed in Trpml1(-/-) parietal cells indicate that Trpml1 functions in the formation and trafficking of the tubulovesicles. This study provides direct evidence for the regulation of gastric acid secretion by a TRP channel; TRPML1 is an important protein in parietal cell apical membrane trafficking.
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Affiliation(s)
- Manjari Chandra
- Department of Internal Medicine, University of Texas, Southwestern Medical Center, 6000 Harry Hines Blvd, Dallas, TX 75390, USA
| | - Hua Zhou
- Department of Internal Medicine, University of Texas, Southwestern Medical Center, 6000 Harry Hines Blvd, Dallas, TX 75390, USA
| | - Qin Li
- Department of Physiology, University of Texas, Southwestern Medical Center, 6000 Harry Hines Blvd, Dallas, TX 75390, USA
| | - Shmuel Muallem
- Department of Physiology, University of Texas, Southwestern Medical Center, 6000 Harry Hines Blvd, Dallas, TX 75390, USA,Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, MD 20892, USA
| | - Sandra L. Hofmann
- Department of Internal Medicine, University of Texas, Southwestern Medical Center, 6000 Harry Hines Blvd, Dallas, TX 75390, USA
| | - Abigail A. Soyombo
- Department of Internal Medicine, University of Texas, Southwestern Medical Center, 6000 Harry Hines Blvd, Dallas, TX 75390, USA,Address correspondence to: Abigail A. Soyombo, Ph.D., Department of Internal Medicine, University of Texas, Southwestern Medical Center, 6000 Harry Hines Blvd, Dallas, Texas 75390-8593, USA, Tel: 214-648-1456, Fax: 214-648-4940,
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Volume density, distribution, and ultrastructure of secretory and basolateral membranes and mitochondria predict parietal cell secretory (dys)function. J Biomed Biotechnol 2010; 2010:394198. [PMID: 20339514 PMCID: PMC2842899 DOI: 10.1155/2010/394198] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2009] [Revised: 11/03/2009] [Accepted: 12/07/2009] [Indexed: 11/24/2022] Open
Abstract
Acid secretion in gastric parietal cells requires highly coordinated membrane transport and vesicle trafficking. Histologically, consensus defines acid secretion as the ratio of the volume density (Vd) of canalicular and apical membranes (CAMs) to tubulovesicular (TV) membranes, a value which varies widely under normal conditions. Examination of numerous achlorhydric mice made it clear that this paradigm is discrepant when used to assess most mice with genetic mutations affecting acid secretion. Vd of organelles in parietal cells of 6 genetically engineered mouse strains was obtained to identify a stable histological phenotype of acid secretion. We confirmed that CAM to TV ratio fairly represented secretory activity in untreated and secretion-inhibited wild-type (WT) mice and in NHE2−/− mice as well, though the response was significantly attenuated in the latter. However, high CAM to TV ratios wrongly posed as active acid secretion in AE2−/−, GHKAα−/−, and NHE4−/− mice. Achlorhydric genotypes also had a significantly higher Vd of basolateral membrane than WT mice, and reduced Vd of mitochondria and canaliculi. The Vd of mitochondria, and ratio of the Vd of basolateral membranes/Vd of mitochondria were preferred predictors of the level of acid secretion. Alterations in acid secretion, then, cause significant changes not only in the Vd of secretory membranes but also in mitochondria and basolateral membranes.
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Abstract
The gastric H,K-ATPase is the primary target for the treatment of acid-related diseases. Proton pump inhibitors (PPIs) are weak bases composed of two moieties, a substituted pyridine with a primary pK(a) of about 4.0, which allows selective accumulation in the secretory canaliculus of the parietal cell, and a benzimidazole with a second pK(a) of about 1.0. PPIs are acid-activated prodrugs that convert to sulfenic acids or sulfenamides that react covalently with one or more cysteines accessible from the luminal surface of the ATPase. Because of covalent binding, their inhibitory effects last much longer than their plasma half-life. However, the short half-life of the drug in the blood and the requirement for acid activation impair their efficacy in acid suppression, particularly at night. PPIs with longer half-life promise to improve acid suppression. All PPIs give excellent healing of peptic ulcers and produce good results in reflux esophagitis. PPIs combined with antibiotics eradicate Helicobacter pylori.
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Affiliation(s)
- Jai Moo Shin
- Membrane Biology, David Geffen School of Medicine, University of California at Los Angeles, Room 324, Building 113, 11301 Wilshire Boulevard, Los Angeles, CA 90073, USA
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Gliddon BL, Nguyen NV, Gunn PA, Gleeson PA, van Driel IR. Isolation, culture and adenoviral transduction of parietal cells from mouse gastric mucosa. Biomed Mater 2008; 3:034117. [DOI: 10.1088/1748-6041/3/3/034117] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Baiocchi L, Tisone G, Russo MA, Longhi C, Palmieri G, Volpe A, Almerighi C, Telesca C, Carbone M, Toti L, De Leonardis F, Angelico M. TUDCA prevents cholestasis and canalicular damage induced by ischemia-reperfusion injury in the rat, modulating PKCalpha-ezrin pathway. Transpl Int 2008; 21:792-800. [PMID: 18435680 DOI: 10.1111/j.1432-2277.2008.00682.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Cholestasis, induced by liver ischemia-reperfusion injury (IRI), is characterized by dilatation of bile canaliculi and loss of microvilli. Tauroursodeoxycholic acid (TUDCA) is an anti-cholestatic agent, modulating protein kinase C (PKC) alpha pathway. PKC reduces ischemic damage in several organs, its isoform alpha modulates ezrin, a key protein in the maintenance of cell lamellipoidal extensions. We evaluated the effects of TUDCA on cholestasis, canalicular changes and PKCalpha-ezrin expression in a rat model of liver IRI. Livers flushed and stored with Belzer solution or Belzer + 10 mm TUDCA (4 degrees C for 6 h) were reperfused (37 degrees C with O(2)) with Krebs-Ringer bicarbonate + 2.5 micromol/min of Taurocholate or TUDCA. Bile was harvested for bile flow assessment. Liver tissue was employed for Electron Microscopy (EM) and for PKCalpha and ezrin immunoblot and immunofluorescence. The same experiments were conducted with the PKCalpha inhibitor Go-6976. TUDCA-treated livers showed increased bile flow (0.25+/-0.17 vs. 0.042+/-0.02 microl/min/g liver, P<0.05) and better preservation of microvilli and bile canalicular area at EM. These effects were associated with increased PKCalpha and ezrin expression (P=0.03 and P=0.04 vs. control respectively), as also confirmed by immunofluorescence data. PKCalpha inhibition abolished these TUDCA effects. TUDCA administration during IRI reduces cholestasis and canalicular damage in the liver modulating PKCalpha-ezrin pathway.
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Shin JM, Munson K, Vagin O, Sachs G. The gastric HK-ATPase: structure, function, and inhibition. Pflugers Arch 2008; 457:609-22. [PMID: 18536934 DOI: 10.1007/s00424-008-0495-4] [Citation(s) in RCA: 167] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2008] [Revised: 03/07/2008] [Accepted: 03/11/2008] [Indexed: 02/06/2023]
Abstract
The gastric H,K-ATPase, a member of the P(2)-type ATPase family, is the integral membrane protein responsible for gastric acid secretion. It is an alpha,beta-heterodimeric enzyme that exchanges cytoplasmic hydronium with extracellular potassium. The catalytic alpha subunit has ten transmembrane segments with a cluster of intramembranal carboxylic amino acids located in the middle of the transmembrane segments TM4, TM5,TM6, and TM8. Comparison to the known structure of the SERCA pump, mutagenesis, and molecular modeling has identified these as constituents of the ion binding domain. The beta subunit has one transmembrane segment with N terminus in cytoplasmic region. The extracellular domain of the beta subunit contains six or seven N-linked glycosylation sites. N-glycosylation is important for the enzyme assembly, maturation, and sorting. The enzyme pumps acid by a series of conformational changes from an E(1) (ion site in) to an E(2) (ion site out) configuration following binding of MgATP and phosphorylation. Several experimental observations support the hypothesis that expulsion of the proton at 160 mM (pH 0.8) results from movement of lysine 791 into the ion binding site in the E(2)P configuration. Potassium access from the lumen depends on activation of a K and Cl conductance via a KCNQ1/KCNE2 complex and Clic6. K movement through the luminal channel in E(2)P is proposed to displace the lysine along with dephosphorylation to return the enzyme to the E(1) configuration. This enzyme is inhibited by the unique proton pump inhibitor class of drug, allowing therapy of acid-related diseases.
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Affiliation(s)
- Jai Moo Shin
- Department of Physiology, David Geffen School of Medicine, University of California at Los Angeles and VA Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA
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Aoyama F, Sawaguchi A, Ide S, Kitamura K, Suganuma T. Exfoliation of gastric pit-parietal cells into the gastric lumen associated with a stimulation of isolated rat gastric mucosa in vitro: a morphological study by the application of cryotechniques. Histochem Cell Biol 2008; 129:785-93. [PMID: 18299880 DOI: 10.1007/s00418-008-0403-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/08/2008] [Indexed: 11/29/2022]
Abstract
It is clinicopathologically important to elucidate the cell kinetics for the maintenance of normal gastric epithelium. In a rat gastric mucosa isolated after stimulation, a number of cells were exfoliated into the gastric lumen of the pit region. The present study was undertaken to clarify the origin of exfoliated cells and their histochemical profiles by taking the advantages of cryotechniques. As results, most of the exfoliated cells were identified as pit-parietal cells labeled with both peanut-lectin and anti-H+/K+-ATPase antibody. Quantitative analysis verified a time-dependent increase in the number of exfoliated cells in the gastric mucosa isolated after stimulation. The exfoliated cells exhibited a diffuse intracellular staining for E-cadherin, suggesting a dissociation of the adhesion molecule prior to the cell exfoliation. It should be noted that most of the exfoliated cells were negative to the apoptotic markers (TUNEL staining and caspase-3). Ultrastructurally, autophagosome-like structures consisting of H+/K+-ATPase positive membranes were frequently seen in the exfoliated pit-parietal cells. In addition, the pit-parietal cell exfoliation was accompanied by sealing of their basal portion with the cytoplasmic processes of adjacent surface mucous cells. The present morphological findings provide a new insight into the cell kinetics in the gastric epithelium in vitro.
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Affiliation(s)
- Fumiyo Aoyama
- Department of Anatomy, Ultrastructural Cell Biology, Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692, Japan
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Sachs G, Shin JM, Vagin O, Lambrecht N, Yakubov I, Munson K. The gastric H,K ATPase as a drug target: past, present, and future. J Clin Gastroenterol 2007; 41 Suppl 2:S226-42. [PMID: 17575528 PMCID: PMC2860960 DOI: 10.1097/mcg.0b013e31803233b7] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The recent progress in therapy if acid disease has relied heavily on the performance of drugs targeted against the H,K ATPase of the stomach and the H2 receptor antagonists. It has become apparent in the last decade that the proton pump is the target that has the likelihood of being the most sustainable area of therapeutic application in the regulation of acid suppression. The process of activation of acid secretion requires a change in location of the ATPase from cytoplasmic tubules into the microvilli of the secretory canaliculus of the parietal cell. Stimulation of the resting parietal cell, with involvement of F-actin and ezrin does not use significant numbers of SNARE proteins, because their message is depleted in the pure parietal cell transcriptome. The cell morphology and gene expression suggest a tubule fusion-eversion event. As the active H,K ATPase requires efflux of KCl for activity we have, using the transcriptome derived from 99% pure parietal cells and immunocytochemistry, provided evidence that the KCl pathway is mediated by a KCQ1/KCNE2 complex for supplying K and CLIC6 for supplying the accompanying Cl. The pump has been modeled on the basis of the structures of different conformations of the sr Ca ATPase related to the catalytic cycle. These models use the effects of site directed mutations and identification of the binding domain of the K competitive acid pump antagonists or the defined site of binding for the covalent class of proton pump inhibitors. The pump undergoes conformational changes associated with phosphorylation to allow the ion binding site to change exposure from cytoplasmic to luminal exposure. We have been able to postulate that the very low gastric pH is achieved by lysine 791 motion extruding the hydronium ion bound to carboxylates in the middle of the membrane domain. These models also allow description of the K entry to form the K liganded form of the enzyme and the reformation of the ion site inward conformation thus relating the catalytic cycle of the pump to conformational models. The mechanism of action of the proton pump inhibitor class of drug is discussed along with the cysteines covalently bound with these inhibitors. The review concludes with a discussion of the mechanism of action and binding regions of a possible new class of drug for acid control, the K competitive acid pump antagonists.
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Affiliation(s)
- George Sachs
- Department of Physiology, David Geffen School of Medicine, University of California at Los Angeles, CA, USA.
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