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Abe K, Ozako M, Inukai M, Matsuyuki Y, Kitayama S, Kanai C, Nagai C, Gopalasingam CC, Gerle C, Shigematsu H, Umekubo N, Yokoshima S, Yoshimori A. Deep learning driven de novo drug design based on gastric proton pump structures. Commun Biol 2023; 6:956. [PMID: 37726448 PMCID: PMC10509173 DOI: 10.1038/s42003-023-05334-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 09/08/2023] [Indexed: 09/21/2023] Open
Abstract
Existing drugs often suffer in their effectiveness due to detrimental side effects, low binding affinity or pharmacokinetic problems. This may be overcome by the development of distinct compounds. Here, we exploit the rich structural basis of drug-bound gastric proton pump to develop compounds with strong inhibitory potency, employing a combinatorial approach utilizing deep generative models for de novo drug design with organic synthesis and cryo-EM structural analysis. Candidate compounds that satisfy pharmacophores defined in the drug-bound proton pump structures, were designed in silico utilizing our deep generative models, a workflow termed Deep Quartet. Several candidates were synthesized and screened according to their inhibition potencies in vitro, and their binding poses were in turn identified by cryo-EM. Structures reaching up to 2.10 Å resolution allowed us to evaluate and re-design compound structures, heralding the most potent compound in this study, DQ-18 (N-methyl-4-((2-(benzyloxy)-5-chlorobenzyl)oxy)benzylamine), which shows a Ki value of 47.6 nM. Further high-resolution cryo-EM analysis at 2.08 Å resolution unambiguously determined the DQ-18 binding pose. Our integrated approach offers a framework for structure-based de novo drug development based on the desired pharmacophores within the protein structure.
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Affiliation(s)
- Kazuhiro Abe
- Cellular and Structural Physiology Institute, Nagoya University, Nagoya, Aichi, 464-8601, Japan.
- Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan.
- Center for One Medicine Innovative Translational Research (COMIT), Nagoya University, Nagoya, Aichi, 464-8601, Japan.
| | - Mami Ozako
- Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | - Miki Inukai
- Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | - Yoe Matsuyuki
- Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | - Shinnosuke Kitayama
- Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | - Chisato Kanai
- INTAGE Healthcare, Inc., 3-5-7, Kawaramachi Chuo-ku, Osaka, 541-0048, Japan
| | - Chiaki Nagai
- Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | | | - Christoph Gerle
- RIKEN SPring-8 Center, Kouto, Sayo-gun, Hyogo, 679-5148, Japan
| | - Hideki Shigematsu
- Japan Synchrotron Radiation Research Institute (JASRI), SPring-8, 1-1-1 Kouto, Sayo, Hyogo, 679-5148, Japan
| | - Nariyoshi Umekubo
- Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | - Satoshi Yokoshima
- Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan.
| | - Atsushi Yoshimori
- Institute for Theoretical Medicine, Inc., 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa, 251-0012, Japan.
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Roldán ML, Ramírez-Salinas GL, Martinez-Archundia M, Cuellar-Perez F, Vilchis-Nestor CA, Cancino-Diaz JC, Shoshani L. The β2-Subunit (AMOG) of Human Na+, K+-ATPase Is a Homophilic Adhesion Molecule. Int J Mol Sci 2022; 23:ijms23147753. [PMID: 35887102 PMCID: PMC9322774 DOI: 10.3390/ijms23147753] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 07/05/2022] [Accepted: 07/05/2022] [Indexed: 12/10/2022] Open
Abstract
The β2 subunit of Na+, K+-ATPase was originally identified as the adhesion molecule on glia (AMOG) that mediates the adhesion of astrocytes to neurons in the central nervous system and that is implicated in the regulation of neurite outgrowth and neuronal migration. While β1 isoform have been shown to trans-interact in a species-specific mode with the β1 subunit on the epithelial neighboring cell, the β2 subunit has been shown to act as a recognition molecule on the glia. Nevertheless, none of the works have identified the binding partner of β2 or described its adhesion mechanism. Until now, the interactions pronounced for β2/AMOG are heterophilic cis-interactions. In the present report we designed experiments that would clarify whether β2 is a cell–cell homophilic adhesion molecule. For this purpose, we performed protein docking analysis, cell–cell aggregation, and protein–protein interaction assays. We observed that the glycosylated extracellular domain of β2/AMOG can make an energetically stable trans-interacting dimer. We show that CHO (Chinese Hamster Ovary) fibroblasts transfected with the human β2 subunit become more adhesive and make large aggregates. The treatment with Tunicamycin in vivo reduced cell aggregation, suggesting the participation of N-glycans in that process. Protein–protein interaction assay in vivo with MDCK (Madin-Darby canine kidney) or CHO cells expressing a recombinant β2 subunit show that the β2 subunits on the cell surface of the transfected cell lines interact with each other. Overall, our results suggest that the human β2 subunit can form trans-dimers between neighboring cells when expressed in non-astrocytic cells, such as fibroblasts (CHO) and epithelial cells (MDCK).
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Affiliation(s)
- María Luisa Roldán
- Department of Physiology, Biophysics and Neurosciences, CINVESTAV-IPN, 2508 IPN Ave., San Pedro Zacatenco, Ciudad de México 07360, Mexico; (M.L.R.); (F.C.-P.); (C.A.V.-N.)
| | - Gema Lizbeth Ramírez-Salinas
- Department of Immunology, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México (UNAM), Circuito, Mario de La Cueva S/N, C.U., Coyoacán, Ciudad de México 04510, Mexico;
| | - Marlet Martinez-Archundia
- Laboratorio de Modelado Molecular, Bioinformática y Diseño de Fármacos, Departamento de Posgrado Escuela Superior de Medicina del Instituto Politécnico Nacional, Salvador Díaz Mirón esq. Plan de San Luis S/N, Miguel Hidalgo, Casco de Santo Tomas, Ciudad de México 11340, Mexico;
| | - Francisco Cuellar-Perez
- Department of Physiology, Biophysics and Neurosciences, CINVESTAV-IPN, 2508 IPN Ave., San Pedro Zacatenco, Ciudad de México 07360, Mexico; (M.L.R.); (F.C.-P.); (C.A.V.-N.)
| | - Claudia Andrea Vilchis-Nestor
- Department of Physiology, Biophysics and Neurosciences, CINVESTAV-IPN, 2508 IPN Ave., San Pedro Zacatenco, Ciudad de México 07360, Mexico; (M.L.R.); (F.C.-P.); (C.A.V.-N.)
| | - Juan Carlos Cancino-Diaz
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Salvador Díaz Mirón esq. Plan de San Luis S/N, Miguel Hidalgo, Casco de Santo Tomas, Ciudad de México 11340, Mexico;
| | - Liora Shoshani
- Department of Physiology, Biophysics and Neurosciences, CINVESTAV-IPN, 2508 IPN Ave., San Pedro Zacatenco, Ciudad de México 07360, Mexico; (M.L.R.); (F.C.-P.); (C.A.V.-N.)
- Correspondence: ; Tel.: +52-55-5747-3360
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3
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Arystarkhova E, Ozelius LJ, Brashear A, Sweadner KJ. Misfolding, altered membrane distributions, and the unfolded protein response contribute to pathogenicity differences in Na,K-ATPase ATP1A3 mutations. J Biol Chem 2021; 296:100019. [PMID: 33144327 PMCID: PMC7949067 DOI: 10.1074/jbc.ra120.015271] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 10/22/2020] [Accepted: 11/03/2020] [Indexed: 02/06/2023] Open
Abstract
Missense mutations in ATP1A3, the α3 isoform of Na,K-ATPase, cause neurological phenotypes that differ greatly in symptoms and severity. A mechanistic basis for differences is lacking, but reduction of activity alone cannot explain them. Isogenic cell lines with endogenous α1 and inducible exogenous α3 were constructed to compare mutation properties. Na,K-ATPase is made in the endoplasmic reticulum (ER), but the glycan-free catalytic α subunit complexes with glycosylated β subunit in the ER to proceed through Golgi and post-Golgi trafficking. We previously observed classic evidence of protein misfolding in mutations with severe phenotypes: differences in ER retention of endogenous β1 subunit, impaired trafficking of α3, and cytopathology, suggesting that they misfold during biosynthesis. Here we tested two mutations associated with different phenotypes: D923N, which has a median age of onset of hypotonia or dystonia at 3 years, and L924P, with severe infantile epilepsy and profound impairment. Misfolding during biosynthesis in the ER activates the unfolded protein response, a multiarmed program that enhances protein folding capacity, and if that fails, triggers apoptosis. L924P showed more nascent protein retention in ER than D923N; more ER-associated degradation of α3 (ERAD); larger differences in Na,K-ATPase subunit distributions among subcellular fractions; and greater inactivation of eIF2α, a major defensive step of the unfolded protein response. In L924P there was also altered subcellular distribution of endogenous α1 subunit, analogous to a dominant negative effect. Both mutations showed pro-apoptotic sensitization by reduced phosphorylation of BAD. Encouragingly, however, 4-phenylbutyrate, a pharmacological corrector, reduced L924P ER retention, increased α3 expression, and restored morphology.
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Affiliation(s)
- Elena Arystarkhova
- Laboratory of Membrane Biology, Department of Neurosurgery, Massachusetts General Hospital, Boston, Massachusetts, USA; Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, USA.
| | - Laurie J Ozelius
- Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Allison Brashear
- Department of Medicine, University of California at Davis Medical School, Sacramento, California, USA
| | - Kathleen J Sweadner
- Laboratory of Membrane Biology, Department of Neurosurgery, Massachusetts General Hospital, Boston, Massachusetts, USA; Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, USA.
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Habeck M, Tokhtaeva E, Nadav Y, Ben Zeev E, Ferris SP, Kaufman RJ, Bab-Dinitz E, Kaplan JH, Dada LA, Farfel Z, Tal DM, Katz A, Sachs G, Vagin O, Karlish SJD. Selective Assembly of Na,K-ATPase α2β2 Heterodimers in the Heart: DISTINCT FUNCTIONAL PROPERTIES AND ISOFORM-SELECTIVE INHIBITORS. J Biol Chem 2016; 291:23159-23174. [PMID: 27624940 DOI: 10.1074/jbc.m116.751735] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Indexed: 12/31/2022] Open
Abstract
The Na,K-ATPase α2 subunit plays a key role in cardiac muscle contraction by regulating intracellular Ca2+, whereas α1 has a more conventional role of maintaining ion homeostasis. The β subunit differentially regulates maturation, trafficking, and activity of α-β heterodimers. It is not known whether the distinct role of α2 in the heart is related to selective assembly with a particular one of the three β isoforms. We show here by immunofluorescence and co-immunoprecipitation that α2 is preferentially expressed with β2 in T-tubules of cardiac myocytes, forming α2β2 heterodimers. We have expressed human α1β1, α2β1, α2β2, and α2β3 in Pichia pastoris, purified the complexes, and compared their functional properties. α2β2 and α2β3 differ significantly from both α2β1 and α1β1 in having a higher K0.5K+ and lower K0.5Na+ for activating Na,K-ATPase. These features are the result of a large reduction in binding affinity for extracellular K+ and shift of the E1P-E2P conformational equilibrium toward E1P. A screen of perhydro-1,4-oxazepine derivatives of digoxin identified several derivatives (e.g. cyclobutyl) with strongly increased selectivity for inhibition of α2β2 and α2β3 over α1β1 (range 22-33-fold). Molecular modeling suggests a possible basis for isoform selectivity. The preferential assembly, specific T-tubular localization, and low K+ affinity of α2β2 could allow an acute response to raised ambient K+ concentrations in physiological conditions and explain the importance of α2β2 for cardiac muscle contractility. The high sensitivity of α2β2 to digoxin derivatives explains beneficial effects of cardiac glycosides for treatment of heart failure and potential of α2β2-selective digoxin derivatives for reducing cardiotoxicity.
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Affiliation(s)
| | - Elmira Tokhtaeva
- the Department of Physiology, School of Medicine, UCLA and Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California 90073
| | - Yotam Nadav
- From the Department of Biomolecular Sciences and
| | - Efrat Ben Zeev
- Israel National Centre for Personalized Medicine, Weizmann Institute of Science, Rehovoth 7610001, Israel
| | - Sean P Ferris
- the Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109
| | - Randal J Kaufman
- the Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109
| | | | - Jack H Kaplan
- the Department of Biochemistry and Molecular Genetics, University of Illinois, Chicago, Illinois 60607, and
| | - Laura A Dada
- the Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Zvi Farfel
- From the Department of Biomolecular Sciences and.,the School of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Daniel M Tal
- From the Department of Biomolecular Sciences and
| | - Adriana Katz
- From the Department of Biomolecular Sciences and
| | - George Sachs
- the Department of Physiology, School of Medicine, UCLA and Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California 90073
| | - Olga Vagin
- the Department of Physiology, School of Medicine, UCLA and Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California 90073,
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Wolf MTF, An SW, Nie M, Bal MS, Huang CL. Klotho up-regulates renal calcium channel transient receptor potential vanilloid 5 (TRPV5) by intra- and extracellular N-glycosylation-dependent mechanisms. J Biol Chem 2014; 289:35849-57. [PMID: 25378396 PMCID: PMC4276853 DOI: 10.1074/jbc.m114.616649] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 10/30/2014] [Indexed: 11/06/2022] Open
Abstract
The anti-aging protein Klotho is a type 1 membrane protein produced predominantly in the distal convoluted tubule. The ectodomain of Klotho is cleaved and secreted into the urine to regulate several ion channels and transporters. Secreted Klotho (sKL) up-regulates the TRPV5 calcium channel from the cell exterior by removing sialic acids from N-glycan of the channel and inhibiting its endocytosis. Because TRPV5 and Klotho coexpress in the distal convoluted tubule, we investigated whether Klotho regulates TRPV5 action from inside the cell. Whole-cell TRPV5-mediated channel activity was recorded in HEK cells coexpressing TRPV5 and sKL or membranous Klotho (mKL). Transfection of sKL, but not mKL, produced detectable Klotho protein in cell culture media. As for sKL, mKL increased TRPV5 current density. The role of sialidase activity of mKL acting inside is supported by findings that mutations of putative sialidase activity sites in sKL and mKL abrogated the regulation of TRPV5 but that the extracellular application of a sialidase inhibitor prevented the regulation of TRPV5 by sKL only. Mechanistically, coexpression with a dominant-negative dynamin II prevented the regulation of TRPV5 by sKL but not by mKL. In contrast, blocking forward trafficking by brefeldin A prevented the effect with mKL but not with sKL. Therefore, Klotho up-regulates TRPV5 from both the inside and outside of cells. The intracellular action of Klotho is likely due to enhanced forward trafficking of channel proteins, whereas the extracellular action is due to inhibition of endocytosis. Both effects involve putative Klotho sialidase activity. These effects of Klotho may play important roles regarding calcium reabsorption in the kidney.
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Affiliation(s)
| | - Sung-Wan An
- Internal Medicine, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | | | | | - Chou-Long Huang
- Internal Medicine, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
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6
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ATP4A gene regulatory network for fine-tuning of proton pump and ion channels. SYSTEMS AND SYNTHETIC BIOLOGY 2013; 7:23-32. [PMID: 24432139 DOI: 10.1007/s11693-012-9103-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 12/31/2012] [Accepted: 12/31/2012] [Indexed: 12/11/2022]
Abstract
The ATP4A encodes α subunit of H(+), K(+)-ATPase that contains catalytic sites of the enzyme forming pores through cell membrane which allows the ion transport. H(+), K(+)-ATPase is a membrane bound P-type ATPase enzyme which is found on the surface of parietal cells and uses the energy derived from each cycle of ATP hydrolysis that can help in exchanging ions (H(+), K(+) and Cl(-)) across the cell membrane secreting acid into the gastric lumen. The 3-D model of α-subunit of H(+), K(+)-ATPase was generated by homology modeling. It was evaluated and validated on the basis of free energies and amino acid residues. The inhibitor binding amino acid active pockets were identified in the 3-D model by molecular docking. The two drugs Omeprazole and Rabeprazole were found more potent interactions with generated model of α-subunit of H(+), K(+)-ATPase on the basis of their affinity between drug-protein interactions. We have generated ATP4A gene regulatory networks for interactions with other proteins which involved in regulation that can help in fine-tuning of proton pump and ion channels. These findings provide a new dimension for discovery and development of proton pump inhibitors and gene regulation of the ATPase. It can be helpful in better understanding of human physiology and also using synthetic biology strategy for reprogramming of parietal cells for control of gastric ulcers.
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Yao S, Bee A, Brewer D, Dodson A, Beesley C, Ke Y, Ambroisine L, Fisher G, Møller H, Dickinson T, Gerard P, Lian LY, Risk J, Lane B, Smith P, Reuter V, Berney D, Gosden C, Scardino P, Cuzick J, Djamgoz MBA, Cooper C, Foster CS. PRKC-ζ Expression Promotes the Aggressive Phenotype of Human Prostate Cancer Cells and Is a Novel Target for Therapeutic Intervention. Genes Cancer 2011; 1:444-64. [PMID: 21779455 DOI: 10.1177/1947601910376079] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 05/25/2010] [Accepted: 05/25/2010] [Indexed: 01/26/2023] Open
Abstract
We show protein kinase C-zeta (PKC-ζ) to be a novel predictive biomarker for survival from prostate cancer (P < 0.001). We also confirm that transcription of the PRKC-ζ gene is crucial to the malignant phenotype of human prostate cancer. Following siRNA silencing of PRKC-ζ in PC3-M prostate cancer cells, stable transfectant cell line si-PRKC-ζ-PC3-M(T1-6) is phenotypically nonmalignant in vitro and in vivo. Genome-wide expression analysis identified 373 genes to be differentially expressed in the knockdown cells and 4 key gene networks to be significantly perturbed during phenotype modulation. Functional interconnection between some of the modulated genes is revealed, although these may be within different regulatory pathways, emphasizing the complexity of their mutual interdependence. Genes with altered expression following PRKC-ζ knockdown include HSPB1, RAD51, and ID1 that we have previously described to be critical in prostatic malignancy. Because expression of PRKC-ζ is functionally involved in promoting the malignant phenotype, we propose PKC-ζ as a novel and biologically relevant target for therapeutic intervention in prostate cancer.
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Affiliation(s)
- Sheng Yao
- Division of Cellular Pathology and Molecular Genetics, University of Liverpool, UK
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8
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He W, Liu W, Chew CS, Baker SS, Baker RD, Forte JG, Zhu L. Acid secretion-associated translocation of KCNJ15 in gastric parietal cells. Am J Physiol Gastrointest Liver Physiol 2011; 301:G591-600. [PMID: 21719736 PMCID: PMC3191558 DOI: 10.1152/ajpgi.00460.2010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Potassium ions are required for gastric acid secretion. Several potassium channels have been implicated in providing K(+) at the apical membrane of parietal cells. In examining the mRNA expression levels between gastric mucosa and liver tissue, KCNJ15 stood out as the most highly specific K(+) channel in the gastric mucosa. Western blot analysis confirmed that KCNJ15 is abundant in the stomach. Immunofluorescence staining of isolated gastric glands indicated that KCNJ15 was expressed in parietal cells and chief cells, but not in mucous neck cells. In resting parietal cells, KCNJ15 was mainly found in puncta throughout the cytoplasm but was distinct from H(+)-K(+)-ATPase. Upon stimulation, KCNJ15 and H(+)-K(+)-ATPase become colocalized on the apical membranes, as suggested by immunofluorescence staining. Western blot analysis of the resting and the stimulated membrane fractions confirmed this observation. From nonsecreting preparations, KCNJ15-containing vesicles sedimented after a 4-h centrifugation at 100,000 g, but not after a 30-min spin, which did sediment most of the H(+)-K(+)-ATPase-containing tubulovesicles. Most of the KCNJ15 containing small vesicle population was depleted upon stimulation of parietal cells, as indicated by the fact that the KCNJ15 signal was shifted to a large membrane fraction that sedimented at 4,000 g. Our results demonstrate that, in nonsecreting parietal cells, KCNJ15 is stored in vesicles distinct from the H(+)-K(+)-ATPase-enriched tubulovesicles. Furthermore, upon stimulation, KCNJ15 and H(+)-K(+)-ATPase both translocate to the apical membrane for active acid secretion. Thus KCNJ15 can be added to the family of apical K(+) channels in gastric parietal cells.
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Affiliation(s)
- Wenjun He
- 1Digestive Diseases and Nutrition Center, Department of Pediatrics, State University of New York at Buffalo, Buffalo, New York;
| | - Wensheng Liu
- 1Digestive Diseases and Nutrition Center, Department of Pediatrics, State University of New York at Buffalo, Buffalo, New York;
| | - Catherine S. Chew
- 2Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, Georgia; and
| | - Susan S. Baker
- 1Digestive Diseases and Nutrition Center, Department of Pediatrics, State University of New York at Buffalo, Buffalo, New York;
| | - Robert D. Baker
- 1Digestive Diseases and Nutrition Center, Department of Pediatrics, State University of New York at Buffalo, Buffalo, New York;
| | - John G. Forte
- 3Department of Molecular and Cell Biology, University of California, Berkeley, California
| | - Lixin Zhu
- 1Digestive Diseases and Nutrition Center, Department of Pediatrics, State University of New York at Buffalo, Buffalo, New York;
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9
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Padilla-Benavides T, Roldán ML, Larre I, Flores-Benitez D, Villegas-Sepúlveda N, Contreras RG, Cereijido M, Shoshani L. The polarized distribution of Na+,K+-ATPase: role of the interaction between {beta} subunits. Mol Biol Cell 2010; 21:2217-25. [PMID: 20444976 PMCID: PMC2893986 DOI: 10.1091/mbc.e10-01-0081] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Na+,K+-ATPase polarity depends on the interaction between the β subunits of Na+,K+-ATPases located on neighboring cells. In the present work, we use energy transfer methods (FRET), in vivo to demonstrate that these β subunits interact directly at the intercellular space of epithelial cells. The very existence of higher metazoans depends on the vectorial transport of substances across epithelia. A crucial element of this transport is the membrane enzyme Na+,K+-ATPase. Not only is this enzyme distributed in a polarized manner in a restricted domain of the plasma membrane but also it creates the ionic gradients that drive the net movement of glucose, amino acids, and ions across the entire epithelium. In a previous work, we have shown that Na+,K+-ATPase polarity depends on interactions between the β subunits of Na+,K+-ATPases located on neighboring cells and that these interactions anchor the entire enzyme at the borders of the intercellular space. In the present study, we used fluorescence resonance energy transfer and coprecipitation methods to demonstrate that these β subunits have sufficient proximity and affinity to permit a direct interaction, without requiring any additional extracellular molecules to span the distance.
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Affiliation(s)
- Teresita Padilla-Benavides
- Department of Physiology Biophysics and Neurosciences, and Department of Molecular Biomedicine, Center for Research and Advanced Studies, CINVESTAV-IPN, Mexico DF 07300, Mexico
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10
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Scillitani G, Mastrodonato M, Liquori GE, Ferri D. Co-Distribution of Glycoconjugates and H+, K+-ATPase in the Parietal Cells of the Greater Horseshoe Bat,Rhinolophus ferrumequinum(Schreber, 1774). Zoolog Sci 2010; 27:433-9. [DOI: 10.2108/zsj.27.433] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Tokhtaeva E, Sachs G, Vagin O. Assembly with the Na,K-ATPase alpha(1) subunit is required for export of beta(1) and beta(2) subunits from the endoplasmic reticulum. Biochemistry 2009; 48:11421-31. [PMID: 19764716 DOI: 10.1021/bi901438z] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The level of the heterodimeric Na,K-ATPase is tightly controlled in epithelia to maintain appropriate transport function. The catalytic Na,K-ATPase alpha subunit is not able to exit the ER or catalyze ion transport unless assembled with the beta subunit. However, requirements for the ER exit of the Na,K-ATPase beta subunit that plays an additional, ion-transport-independent, role in intercellular adhesion are not clear. Exogenous beta(1) or beta(2) subunits expressed in renal MDCK cells replace endogenous beta(1) subunits in the alpha-beta complexes in the ER, resulting in a decrease in the amount of the alpha(1)-bound endogenous beta(1) subunits by 47-61% with no change in the amount of alpha(1) subunits. Disruption of the alpha(1)-beta association by mutations in defined alpha(1)-interacting regions of either beta(1) or beta(2) subunits results in the ER retention and rapid degradation of unassembled mutants. Hence, the ER quality control system allows export only of assembled alpha-beta complexes to the Golgi, thereby maintaining an equimolar ratio of alpha and beta subunits in the plasma membrane, whereas the number of alpha(1) subunits in the ER determines the amount of the alpha-beta complexes.
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Affiliation(s)
- Elmira Tokhtaeva
- Department of Physiology, School of Medicine, UCLA and Veterans Administration Greater Los Angeles Health Care System, Los Angeles, USA
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12
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Bab-Dinitz E, Albeck S, Peleg Y, Brumfeld V, Gottschalk KE, Karlish SJD. A C-Terminal Lobe of the β Subunit of Na,K-ATPase and H,K-ATPase Resembles Cell Adhesion Molecules. Biochemistry 2009; 48:8684-91. [DOI: 10.1021/bi900868e] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | | | | | - Kay E. Gottschalk
- Department of Applied Physics, Ludwig-Maximilians Universität, 80799 München, Germany
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Chang XB, Mengos A, Hou YX, Cui L, Jensen TJ, Aleksandrov A, Riordan JR, Gentzsch M. Role of N-linked oligosaccharides in the biosynthetic processing of the cystic fibrosis membrane conductance regulator. J Cell Sci 2008; 121:2814-23. [PMID: 18682497 DOI: 10.1242/jcs.028951] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The epithelial chloride channel CFTR is a glycoprotein that is modified by two N-linked oligosaccharides. The most common mutant CFTR protein in patients with cystic fibrosis, DeltaF508, is misfolded and retained by ER quality control. As oligosaccharide moieties of glycoproteins are known to mediate interactions with ER lectin chaperones, we investigated the role of N-linked glycosylation in the processing of wild-type and DeltaF508 CFTR. We found that N-glycosylation and ER lectin interactions are not major determinants of trafficking of wild-type and DeltaF508 from the ER to the plasma membrane. Unglycosylated CFTR, generated by removal of glycosylation sites or treatment of cells with the N-glycosylation inhibitor tunicamycin, did not bind calnexin, but did traffic to the cell surface and exhibited chloride channel activity. Most importantly, unglycosylated DeltaF508 CFTR still could not escape quality control in the early secretory pathway and remained associated with the ER. However, the absence of N-linked oligosaccharides did reduce the stability of wild-type CFTR, causing significantly more-rapid turnover in post-ER compartments. Surprisingly, the individual N-linked carbohydrates do not play equivalent roles and modulate the fate of the wild-type protein in different ways in its early biosynthetic pathway.
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Affiliation(s)
- Xiu-Bao Chang
- Mayo Clinic College of Medicine, Mayo Clinic Arizona, Scottsdale, AZ 85259, USA
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Dürr KL, Tavraz NN, Zimmermann D, Bamberg E, Friedrich T. Characterization of Na,K-ATPase and H,K-ATPase Enzymes with Glycosylation-Deficient β-Subunit Variants by Voltage-Clamp Fluorometry in Xenopus Oocytes. Biochemistry 2008; 47:4288-97. [DOI: 10.1021/bi800092k] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Katharina L. Dürr
- Max Volmer Laboratory for Biophysical Chemistry, Institute of Chemistry, Technical University of Berlin, Secr. PC 14, Strasse des 17. Juni 135, D-10623 Berlin, Germany, Department of Biophysical Chemistry, Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, D-60438 Frankfurt/Main, Germany, and Chemical and Pharmaceutical Sciences Department, Johann Wolfgang Goethe University Frankfurt, Max-von-Laue-Strasse 1, 7-9, D-60439 Frankfurt/Main, Germany
| | - Neslihan N. Tavraz
- Max Volmer Laboratory for Biophysical Chemistry, Institute of Chemistry, Technical University of Berlin, Secr. PC 14, Strasse des 17. Juni 135, D-10623 Berlin, Germany, Department of Biophysical Chemistry, Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, D-60438 Frankfurt/Main, Germany, and Chemical and Pharmaceutical Sciences Department, Johann Wolfgang Goethe University Frankfurt, Max-von-Laue-Strasse 1, 7-9, D-60439 Frankfurt/Main, Germany
| | - Dirk Zimmermann
- Max Volmer Laboratory for Biophysical Chemistry, Institute of Chemistry, Technical University of Berlin, Secr. PC 14, Strasse des 17. Juni 135, D-10623 Berlin, Germany, Department of Biophysical Chemistry, Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, D-60438 Frankfurt/Main, Germany, and Chemical and Pharmaceutical Sciences Department, Johann Wolfgang Goethe University Frankfurt, Max-von-Laue-Strasse 1, 7-9, D-60439 Frankfurt/Main, Germany
| | - Ernst Bamberg
- Max Volmer Laboratory for Biophysical Chemistry, Institute of Chemistry, Technical University of Berlin, Secr. PC 14, Strasse des 17. Juni 135, D-10623 Berlin, Germany, Department of Biophysical Chemistry, Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, D-60438 Frankfurt/Main, Germany, and Chemical and Pharmaceutical Sciences Department, Johann Wolfgang Goethe University Frankfurt, Max-von-Laue-Strasse 1, 7-9, D-60439 Frankfurt/Main, Germany
| | - Thomas Friedrich
- Max Volmer Laboratory for Biophysical Chemistry, Institute of Chemistry, Technical University of Berlin, Secr. PC 14, Strasse des 17. Juni 135, D-10623 Berlin, Germany, Department of Biophysical Chemistry, Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, D-60438 Frankfurt/Main, Germany, and Chemical and Pharmaceutical Sciences Department, Johann Wolfgang Goethe University Frankfurt, Max-von-Laue-Strasse 1, 7-9, D-60439 Frankfurt/Main, Germany
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The roles of the Na,K-ATPase beta 1 subunit in pump sorting and epithelial integrity. J Bioenerg Biomembr 2007; 39:367-72. [DOI: 10.1007/s10863-007-9103-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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