1
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van der Veen RE, Piontek J, Bieck M, Saiti A, Gonschior H, Lehmann M. Claudin-4 polymerizes after a small extracellular claudin-3-like substitution. J Biol Chem 2024:107693. [PMID: 39159821 DOI: 10.1016/j.jbc.2024.107693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 07/14/2024] [Accepted: 08/09/2024] [Indexed: 08/21/2024] Open
Abstract
Tight junctions play a pivotal role in the functional integrity of the human body by forming barriers that compartmentalize tissues and protect the body from external threats. Essential components of tight junctions are the transmembrane claudin proteins, which can polymerize into tight junction strands and meshworks. This study delves into the structural determinants of claudin polymerization, utilizing the close homology yet strong difference in polymerization capacity between claudin-3 and claudin-4. Through a combination of sequence alignment and structural modeling, critical residues in the second extracellular segment are pinpointed. Molecular dynamics simulations provide insights into the interactions of and the conformational changes induced by the identified extracellular segment 2 residues. Live-STED imaging demonstrates that introduction of these residues from claudin-3 into claudin-4 significantly enhances polymerization in non-epithelial cells. In tight junction-deficient epithelial cells, mutated claudin-4 not only influences tight junction morphology but also partially restores barrier function. Understanding the structural basis of claudin polymerization is crucial, as it offers insights into the dynamic nature of tight junctions. This knowledge could be applied to targeted therapeutic interventions, offering insight to repair or prevent barrier defects associated with pathological conditions, or introduce temporary barrier openings during drug delivery.
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Affiliation(s)
| | - Jörg Piontek
- Clinical Physiology/Nutritional Medicine, Department of Gastroenterology, Rheumatology and Infectious Diseases, Charité-Universitätsmedizin Berlin, Hindenburgdamm 30, 12203 Berlin, Germany
| | - Marie Bieck
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany
| | - Arbesa Saiti
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany
| | - Hannes Gonschior
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany
| | - Martin Lehmann
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany.
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2
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Apostolova D, Apostolov G, Moten D, Batsalova T, Dzhambazov B. Claudin-12: guardian of the tissue barrier or friend of tumor cells. Tissue Barriers 2024:2387408. [PMID: 39087432 DOI: 10.1080/21688370.2024.2387408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2024] [Revised: 07/28/2024] [Accepted: 07/28/2024] [Indexed: 08/02/2024] Open
Abstract
Tight junctions (TJs) are an important component of cellular connectivity. Claudin family proteins, as a constituent of TJs, determine their barrier properties, cell polarity and paracellular permeability. Claudin-12 is an atypical member of the claudin family, as it belongs to the group of non-classical claudins that lack a PDZ-binding domain. It has been shown that claudin-12 is involved in paracellular Ca2+ transients and it is present in normal and hyperplastic tissues in addition to neoplastic tissues. Dysregulation of claudin-12 expression has been reported in various cancers, suggesting that this protein may play an important role in cancer cell migration, invasion, and metastasis. Some studies have shown that claudin-12 gene functions as a tumor suppressor, but others have reported that overexpression of claudin-12 significantly increases the metastatic properties of various tumor cells. Investigating this dual role of claudin-12 is of utmost importance and should therefore be studied in detail. The aim of this review is to provide an overview of the information available to date on claudin-12, including its structure, expression in various tissues and substances that may affect it, with a final focus on its role in cancer.
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Affiliation(s)
- Desislava Apostolova
- Department of Developmental Biology, Faculty of Biology, Paisii Hilendarski University of Plovdiv, Plovdiv, Bulgaria
| | - Georgi Apostolov
- Department of Neurosurgery, Faculty of Medicine, Medical University of Plovdiv, Plovdiv, Bulgaria
| | - Dzhemal Moten
- Department of Developmental Biology, Faculty of Biology, Paisii Hilendarski University of Plovdiv, Plovdiv, Bulgaria
| | - Tsvetelina Batsalova
- Department of Developmental Biology, Faculty of Biology, Paisii Hilendarski University of Plovdiv, Plovdiv, Bulgaria
| | - Balik Dzhambazov
- Department of Developmental Biology, Faculty of Biology, Paisii Hilendarski University of Plovdiv, Plovdiv, Bulgaria
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3
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Mungara P, Waiss M, Hartwig S, Burger D, Cordat E. Unraveling the molecular landscape of kAE1: a narrative review. Can J Physiol Pharmacol 2024; 102:396-407. [PMID: 38669699 DOI: 10.1139/cjpp-2023-0482] [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: 04/28/2024]
Abstract
Kidney anion exchanger 1 (kAE1) is an isoform of the AE1 protein encoded by the SLC4A1 gene. It is a basolateral membrane protein expressed by α-intercalated cells in the connecting tubules and collecting duct of the kidney. Its main function is to exchange bicarbonate and chloride ions between the blood and urine to maintain blood pH at physiological threshold. The kAE1 protein undergoes multiple post-translational modifications such as phosphorylation and ubiquitination and interacts with many different proteins such as claudin-4 and carbonic anhydrase II. Mutations in the gene may lead to the development of distal renal tubular acidosis, characterized by the failure to acidify the urine, which may result in nephrocalcinosis and in more severe cases, renal failure. In this review, we discuss the structure and function of kAE1, its post-translational modifications, and protein-protein interactions. Finally, we discuss insights gained from the study of kAE1 mutations in humans and in mice.
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Affiliation(s)
- Priyanka Mungara
- Department of Physiology, Membrane Protein Disease Research Group, Faculty of Medicine, College of Health Sciences, University of Alberta, Edmonton, AB, Canada
| | - Moubarak Waiss
- School of Pharmaceutical Sciences, University of Ottawa, Ottawa, ON, Canada
| | - Sunny Hartwig
- Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada
| | - Dylan Burger
- School of Pharmaceutical Sciences, University of Ottawa, Ottawa, ON, Canada
- Ottawa Hospital Research Institute, Kidney Research Centre, Ottawa, ON, Canada
| | - Emmanuelle Cordat
- Department of Physiology, Membrane Protein Disease Research Group, Faculty of Medicine, College of Health Sciences, University of Alberta, Edmonton, AB, Canada
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4
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Wachiradejkul W, Pongkorpsakol P. Inter-claudin antagonism of paracellular pore function: mechanism and beyond. Tissue Barriers 2024:2330773. [PMID: 38494648 DOI: 10.1080/21688370.2024.2330773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Accepted: 03/11/2024] [Indexed: 03/19/2024] Open
Abstract
Claudin-2-dependent pore function mediates paracellular cation permeability and can result in pathogenesis of many diseases. Although existing various types of claudins, including barrier-forming and pore-forming claudins, their heterodimeric interaction affecting barrier and pore functions has never been fully elucidated yet. Recently, Shashikanth and colleagues demonstrated that expression of claudin-4 was able to antagonize paracellular pore activity of claudin-2. This commentary will emphasize the mechanism underlying claudin-4-mediated claudin-2-dependent pore inhibition and discuss its potential therapeutic and prognostic applications.
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Affiliation(s)
- Wanapas Wachiradejkul
- Princess Srisavangavadhana College of Medicine, Chulabhorn Royal Academy, Bangkok, Thailand
| | - Pawin Pongkorpsakol
- Princess Srisavangavadhana College of Medicine, Chulabhorn Royal Academy, Bangkok, Thailand
- Laboratory of Epithelial Tight Junction Pathophysiology, Bangkok, Thailand
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5
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Alija Ç, Knobe L, Pouyiourou I, Furuse M, Rosenthal R, Günzel D. Integrating Continuous Transepithelial Flux Measurements into an Ussing Chamber Set-Up. Int J Mol Sci 2024; 25:2252. [PMID: 38396929 PMCID: PMC10889482 DOI: 10.3390/ijms25042252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Revised: 01/29/2024] [Accepted: 02/08/2024] [Indexed: 02/25/2024] Open
Abstract
Fluorescently labelled compounds are often employed to study the paracellular properties of epithelia. For flux measurements, these compounds are added to the donor compartment and samples collected from the acceptor compartment at regular intervals. However, this method fails to detect rapid changes in permeability. For continuous transepithelial flux measurements in an Ussing chamber setting, a device was developed, consisting of a flow-through chamber with an attached LED, optical filter, and photodiode, all encased in a light-impermeable container. The photodiode output was amplified and recorded. Calibration with defined fluorescein concentration (range of 1 nM to 150 nM) resulted in a linear output. As proof of principle, flux measurements were performed on various cell lines. The results confirmed a linear dependence of the flux on the fluorescein concentration in the donor compartment. Flux depended on paracellular barrier function (expression of specific tight junction proteins, and EGTA application to induce barrier loss), whereas activation of transcellular chloride secretion had no effect on fluorescein flux. Manipulation of the lateral space by osmotic changes in the perfusion solution also affected transepithelial fluorescein flux. In summary, this device allows a continuous recording of transepithelial flux of fluorescent compounds in parallel with the electrical parameters recorded by the Ussing chamber.
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Affiliation(s)
- Çlirim Alija
- Clinical Physiology/Nutritional Medicine, Medical Department, Division of Gastroenterology, Infectiology, Rheumatology, Charité–Universitätsmedizin Berlin, 12203 Berlin, Germany; (Ç.A.); (L.K.); (I.P.); (R.R.)
| | - Lukas Knobe
- Clinical Physiology/Nutritional Medicine, Medical Department, Division of Gastroenterology, Infectiology, Rheumatology, Charité–Universitätsmedizin Berlin, 12203 Berlin, Germany; (Ç.A.); (L.K.); (I.P.); (R.R.)
| | - Ioanna Pouyiourou
- Clinical Physiology/Nutritional Medicine, Medical Department, Division of Gastroenterology, Infectiology, Rheumatology, Charité–Universitätsmedizin Berlin, 12203 Berlin, Germany; (Ç.A.); (L.K.); (I.P.); (R.R.)
| | - Mikio Furuse
- Division of Cell Structure, National Institute for Physiological Sciences, Okazaki, Aichi 444-8787, Japan;
| | - Rita Rosenthal
- Clinical Physiology/Nutritional Medicine, Medical Department, Division of Gastroenterology, Infectiology, Rheumatology, Charité–Universitätsmedizin Berlin, 12203 Berlin, Germany; (Ç.A.); (L.K.); (I.P.); (R.R.)
| | - Dorothee Günzel
- Clinical Physiology/Nutritional Medicine, Medical Department, Division of Gastroenterology, Infectiology, Rheumatology, Charité–Universitätsmedizin Berlin, 12203 Berlin, Germany; (Ç.A.); (L.K.); (I.P.); (R.R.)
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6
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Lashhab R, Essuman G, Chavez-Canales M, Alexander RT, Cordat E. Expression of the kidney anion exchanger 1 affects WNK4 and SPAK phosphorylation and results in claudin-4 phosphorylation. Heliyon 2023; 9:e22280. [PMID: 38034706 PMCID: PMC10687047 DOI: 10.1016/j.heliyon.2023.e22280] [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: 05/24/2023] [Revised: 11/07/2023] [Accepted: 11/08/2023] [Indexed: 12/02/2023] Open
Abstract
In the renal collecting ducts, chloride reabsorption occurs through both transcellular and paracellular pathways. Recent literature highlights a functional interplay between both pathways. We recently showed that in polarized inner medullary collecting duct cells, expression of the basolateral kidney anion exchanger 1 (kAE1) results in a decreased transepithelial electrical resistance (TEER), in a claudin-4 dependent pathway. Claudin-4 is a paracellular sodium blocker and chloride pore. Here, we show that kAE1 expression in mouse inner medullary collecting duct cells triggers WNK4, SPAK and claudin-4 phosphorylation. Expression of a functionally dead kAE1 E681Q mutant has no effect on phosphorylation of these proteins. Expression of a catalytically inactive WNK4 D321A or chloride-insensitive WNK4 L319F mutant abolishes kAE1 effect on TEER, supporting a contribution of WNK4 to the process. We propose that variations of the cytosolic pH and chloride concentration upon kAE1 expression alter WNK4 kinase activity and tight junction properties.
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Affiliation(s)
- Rawad Lashhab
- Department of Physiology and Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Grace Essuman
- Department of Physiology and Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Maria Chavez-Canales
- Unidad de Investigación UNAM-INCICh, Instituto Nacional de Cardiología Ignacio Chávez and Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Tlalpan, Mexico City, 14080, Mexico
| | - R. Todd Alexander
- Department of Physiology and Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - Emmanuelle Cordat
- Department of Physiology and Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
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7
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Abstract
Sequential expression of claudins, a family of tight junction proteins, along the nephron mirrors the sequential expression of ion channels and transporters. Only by the interplay of transcellular and paracellular transport can the kidney efficiently maintain electrolyte and water homeostasis in an organism. Although channel and transporter defects have long been known to perturb homeostasis, the contribution of individual tight junction proteins has been less clear. Over the past two decades, the regulation and dysregulation of claudins have been intensively studied in the gastrointestinal tract. Claudin expression patterns have, for instance, been found to be affected in infection and inflammation, or in cancer. In the kidney, a deeper understanding of the causes as well as the effects of claudin expression alterations is only just emerging. Little is known about hormonal control of the paracellular pathway along the nephron, effects of cytokines on renal claudin expression or relevance of changes in paracellular permeability to the outcome in any of the major kidney diseases. By summarizing current findings on the role of specific claudins in maintaining electrolyte and water homeostasis, this Review aims to stimulate investigations on claudins as prognostic markers or as druggable targets in kidney disease.
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Affiliation(s)
- Luca Meoli
- Clinical Physiology/Nutritional Medicine, Medical Department, Division of Gastroenterology, Infectiology, Rheumatology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Dorothee Günzel
- Clinical Physiology/Nutritional Medicine, Medical Department, Division of Gastroenterology, Infectiology, Rheumatology, Charité - Universitätsmedizin Berlin, Berlin, Germany.
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8
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Alexander RT. Kidney stones, hypercalciuria, and recent insights into proximal tubule calcium reabsorption. Curr Opin Nephrol Hypertens 2023; 32:359-365. [PMID: 37074688 DOI: 10.1097/mnh.0000000000000892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2023]
Abstract
PURPOSE OF REVIEW Most kidney stones are composed of calcium, and the greatest risk factor for kidney stone formation is hypercalciuria. Patients who form kidney stones often have reduced calcium reabsorption from the proximal tubule, and increasing this reabsorption is a goal of some dietary and pharmacological treatment strategies to prevent kidney stone recurrence. However, until recently, little was known about the molecular mechanism that mediates calcium reabsorption from the proximal tubule. This review summarizes newly uncovered key insights and discusses how they may inform the treatment of kidney stone formers. RECENT FINDINGS Studies examining claudin-2 and claudin-12 single and double knockout mice, combined with cell culture models, support complementary independent roles for these tight junction proteins in contributing paracellular calcium permeability to the proximal tubule. Moreover, a family with a coding variation in claudin-2 causing hypercalciuria and kidney stones have been reported, and reanalysis of Genome Wide Association Study (GWAS) data demonstrates an association between noncoding variations in CLDN2 and kidney stone formation. SUMMARY The current work begins to delineate the molecular mechanisms whereby calcium is reabsorbed from the proximal tubule and suggests a role for altered claudin-2 mediated calcium reabsorption in the pathogenesis of hypercalciuria and kidney stone formation.
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Affiliation(s)
- R Todd Alexander
- Department of Pediatrics
- Department of Physiology, University of Alberta
- The Women's & Children's Health Research Institute, Edmonton, Alberta, Canada
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9
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Berselli A, Benfenati F, Maragliano L, Alberini G. Multiscale modelling of claudin-based assemblies: a magnifying glass for novel structures of biological interfaces. Comput Struct Biotechnol J 2022; 20:5984-6010. [DOI: 10.1016/j.csbj.2022.10.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 10/24/2022] [Accepted: 10/24/2022] [Indexed: 11/03/2022] Open
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10
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Berselli A, Alberini G, Benfenati F, Maragliano L. Computational study of ion permeation through claudin-4 paracellular channels. Ann N Y Acad Sci 2022; 1516:162-174. [PMID: 35811406 PMCID: PMC9796105 DOI: 10.1111/nyas.14856] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Claudins (Cldns) form a large family of protein homologs that are essential for the assembly of paracellular tight junctions (TJs), where they form channels or barriers with tissue-specific selectivity for permeants. In contrast to several family members whose physiological role has been identified, the function of claudin 4 (Cldn4) remains elusive, despite experimental evidence suggesting that it can form anion-selective TJ channels in the renal epithelium. Computational approaches have recently been employed to elucidate the molecular basis of Cldns' function, and hence could help in clarifying the role of Cldn4. In this work, we use structural modeling and all-atom molecular dynamics simulations to transfer two previously introduced structural models of Cldn-based paracellular complexes to Cldn4 to reproduce a paracellular anion channel. Free energy calculations for ionic transport through the pores allow us to establish the thermodynamic properties driving the ion-selectivity of the structures. While one model shows a cavity permeable to chloride and repulsive to cations, the other forms barrier to the passage of all the major physiological ions. Furthermore, our results confirm the charge selectivity role of the residue Lys65 in the first extracellular loop of the protein, rationalizing Cldn4 control of paracellular permeability.
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Affiliation(s)
- Alessandro Berselli
- Center for Synaptic Neuroscience and Technology (NSYN@UniGe)Istituto Italiano di TecnologiaGenovaItaly,Department of Experimental MedicineUniversità degli Studi di GenovaGenovaItaly
| | - Giulio Alberini
- Center for Synaptic Neuroscience and Technology (NSYN@UniGe)Istituto Italiano di TecnologiaGenovaItaly,IRCCS Ospedale Policlinico San MartinoGenovaItaly
| | - Fabio Benfenati
- Center for Synaptic Neuroscience and Technology (NSYN@UniGe)Istituto Italiano di TecnologiaGenovaItaly,IRCCS Ospedale Policlinico San MartinoGenovaItaly
| | - Luca Maragliano
- Center for Synaptic Neuroscience and Technology (NSYN@UniGe)Istituto Italiano di TecnologiaGenovaItaly,Department of Life and Environmental SciencesPolytechnic University of MarcheAnconaItaly
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11
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Shashikanth N, France MM, Xiao R, Haest X, Rizzo HE, Yeste J, Reiner J, Turner JR. Tight junction channel regulation by interclaudin interference. Nat Commun 2022; 13:3780. [PMID: 35773259 PMCID: PMC9246906 DOI: 10.1038/s41467-022-31587-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 06/23/2022] [Indexed: 02/06/2023] Open
Abstract
Tight junctions form selectively permeable seals across the paracellular space. Both barrier function and selective permeability have been attributed to members of the claudin protein family, which can be categorized as pore-forming or barrier-forming. Here, we show that claudin-4, a prototypic barrier-forming claudin, reduces paracellular permeability by a previously unrecognized mechanism. Claudin-4 knockout or overexpression has minimal effects on tight junction permeability in the absence of pore-forming claudins. However, claudin-4 selectively inhibits flux across cation channels formed by claudins 2 or 15. Claudin-4-induced loss of claudin channel function is accompanied by reduced anchoring and subsequent endocytosis of pore-forming claudins. Analyses in nonepithelial cells show that claudin-4, which is incapable of independent polymerization, disrupts polymeric strands and higher order meshworks formed by claudins 2, 7, 15, and 19. This process of interclaudin interference, in which one claudin disrupts higher order structures and channels formed by a different claudin, represents a previously unrecognized mechanism of barrier regulation.
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Affiliation(s)
- Nitesh Shashikanth
- Laboratory of Mucosal Barrier Pathobiology, Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Marion M France
- Laboratory of Mucosal Barrier Pathobiology, Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Ruyue Xiao
- Laboratory of Mucosal Barrier Pathobiology, Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Xenia Haest
- Laboratory of Mucosal Barrier Pathobiology, Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Heather E Rizzo
- Laboratory of Mucosal Barrier Pathobiology, Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Jose Yeste
- Laboratory of Mucosal Barrier Pathobiology, Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
- Instituto de Microelectrónica de Barcelona, IMB-CNM (CSIC), Bellaterra, Spain
| | - Johannes Reiner
- Division of Gastroenterology and Endocrinology, Department of Medicine II, Rostock University Medical Center, Ernst-Heydemann-Str. 6, Rostock, Germany
| | - Jerrold R Turner
- Laboratory of Mucosal Barrier Pathobiology, Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
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12
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Beggs MR, Young K, Pan W, O'Neill DD, Saurette M, Plain A, Rievaj J, Doschak MR, Cordat E, Dimke H, Alexander RT. Claudin-2 and claudin-12 form independent, complementary pores required to maintain calcium homeostasis. Proc Natl Acad Sci U S A 2021; 118:e2111247118. [PMID: 34810264 PMCID: PMC8694054 DOI: 10.1073/pnas.2111247118] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/18/2021] [Indexed: 12/29/2022] Open
Abstract
Calcium (Ca2+) homeostasis is maintained through coordination between intestinal absorption, renal reabsorption, and bone remodeling. Intestinal and renal (re)absorption occurs via transcellular and paracellular pathways. The latter contributes the bulk of (re)absorption under conditions of adequate intake. Epithelial paracellular permeability is conferred by tight-junction proteins called claudins. However, the molecular identity of the paracellular Ca2+ pore remains to be delineated. Claudins (Cldn)-2 and -12 confer Ca2+ permeability, but deletion of either claudin does not result in a negative Ca2+ balance or increased calciotropic hormone levels, suggesting the existence of additional transport pathways or parallel roles for the two claudins. To test this, we generated a Cldn2/12 double knockout mouse (DKO). These animals have reduced intestinal Ca2+ absorption. Colonic Ca2+ permeability is also reduced in DKO mice and significantly lower than single-null animals, while small intestine Ca2+ permeability is unaltered. The DKO mice display significantly greater urinary Ca2+ wasting than Cldn2 null animals. These perturbations lead to hypocalcemia and reduced bone mineral density, which was not observed in single-KO animals. Both claudins were localized to colonic epithelial crypts and renal proximal tubule cells, but they do not physically interact in vitro. Overexpression of either claudin increased Ca2+ permeability in cell models with endogenous expression of the other claudin. We find claudin-2 and claudin-12 form partially redundant, independent Ca2+ permeable pores in renal and colonic epithelia that enable paracellular Ca2+ (re)absorption in these segments, with either one sufficient to maintain Ca2+ balance.
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Affiliation(s)
- Megan R Beggs
- Department of Physiology, University of Alberta, Edmonton, AB, T6G 2H7, Canada
- Women's and Children's Health Research Institute, Edmonton, AB, T6G 1C9, Canada
| | - Kennedi Young
- Department of Physiology, University of Alberta, Edmonton, AB, T6G 2H7, Canada
| | - Wanling Pan
- Department of Physiology, University of Alberta, Edmonton, AB, T6G 2H7, Canada
| | - Debbie D O'Neill
- Department of Physiology, University of Alberta, Edmonton, AB, T6G 2H7, Canada
| | - Matthew Saurette
- Department of Physiology, University of Alberta, Edmonton, AB, T6G 2H7, Canada
| | - Allein Plain
- Department of Physiology, University of Alberta, Edmonton, AB, T6G 2H7, Canada
| | - Juraj Rievaj
- Department of Physiology, University of Alberta, Edmonton, AB, T6G 2H7, Canada
| | - Michael R Doschak
- Faculty of Pharmacy & Pharmaceutical Sciences, University of Alberta, Edmonton, AB, T6G 2H5, Canada
| | - Emmanuelle Cordat
- Department of Physiology, University of Alberta, Edmonton, AB, T6G 2H7, Canada
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, 5000 Odense, Denmark
- Department of Nephrology, Odense University Hospital, 5000 Odense, Denmark
| | - R Todd Alexander
- Department of Physiology, University of Alberta, Edmonton, AB, T6G 2H7, Canada;
- Women's and Children's Health Research Institute, Edmonton, AB, T6G 1C9, Canada
- Department of Pediatrics, University of Alberta, Edmonton, AB, T6G 1C9, Canada
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13
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Wu S, Li L, Wu X, Wong CKC, Sun F, Cheng CY. AKAP9 supports spermatogenesis through its effects on microtubule and actin cytoskeletons in the rat testis. FASEB J 2021; 35:e21925. [PMID: 34569663 DOI: 10.1096/fj.202100960r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 08/16/2021] [Accepted: 08/31/2021] [Indexed: 12/29/2022]
Abstract
In mammalian testes, extensive remodeling of the microtubule (MT) and actin cytoskeletons takes place in Sertoli cells across the seminiferous epithelium to support spermatogenesis. However, the mechanism(s) involving regulatory and signaling proteins remains poorly understood. Herein, A-kinase anchoring protein 9 (AKAP9, a member of the AKAP multivalent scaffold protein family) was shown to be one of these crucial regulatory proteins in the rat testis. Earlier studies have shown that AKAP9 serves as a signaling platform by recruiting multiple signaling and regulatory proteins to create a large protein complex that binds to the Golgi and centrosome to facilitate the assembly of the MT-nucleating γ-tubulin ring complex to initiate MT polymerization. We further expanded our earlier studies based on a Sertoli cell-specific AKAP9 knockout mouse model to probe the function of AKAP9 by using the techniques of immunofluorescence analysis, RNA interference (RNAi), and biochemical assays on an in vitro primary Sertoli cell culture model, and an adjudin-based animal model. AKAP9 robustly expressed across the seminiferous epithelium in adult rat testes, colocalizing with MT-based tracks, and laid perpendicular across the seminiferous epithelium, and prominently expressed at the Sertoli-spermatid cell-cell anchoring junction (called apical ectoplasmic specialization [ES]) and at the Sertoli cell-cell interface (called basal ES, which together with tight junction [TJ] created the blood-testis barrier [BTB]) stage specifically. AKAP9 knockdown in Sertoli cells by RNAi was found to perturb the TJ-permeability barrier through disruptive changes in the distribution of BTB-associated proteins at the Sertoli cell cortical zone, mediated by a considerable loss of ability to induce both MT polymerization and actin filament bundling. A considerable decline in AKAP9 expression and a disruptive distribution of AKAP9 across the seminiferous tubules was also noted during adjudin-induced germ cell (GC) exfoliation in this animal model, illustrating AKAP9 is essential to maintain the homeostasis of cytoskeletons to maintain Sertoli and GC adhesion in the testis.
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Affiliation(s)
- Siwen Wu
- The Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, China.,The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York, USA
| | - Linxi Li
- The Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, China
| | - Xiaolong Wu
- Institute of Reproductive Medicine, Nantong University School of Medicine, Nantong, China
| | - Chris K C Wong
- Department of Biology, Croucher Institute for Environmental Sciences, Hong Kong Baptist University, Kowloon, China
| | - Fei Sun
- Institute of Reproductive Medicine, Nantong University School of Medicine, Nantong, China
| | - C Yan Cheng
- The Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, China.,The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York, USA
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Li Y, Liu M, Liu H, Sui X, Liu Y, Wei X, Liu C, Cheng Y, Ye W, Gao B, Wang X, Lu Q, Cheng H, Zhang L, Yuan J, Li M. The Anti-Inflammatory Effect and Mucosal Barrier Protection of Clostridium butyricum RH2 in Ceftriaxone-Induced Intestinal Dysbacteriosis. Front Cell Infect Microbiol 2021; 11:647048. [PMID: 33842393 PMCID: PMC8027357 DOI: 10.3389/fcimb.2021.647048] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Accepted: 02/26/2021] [Indexed: 12/12/2022] Open
Abstract
This study aimed at determining the beneficial effect of Clostridium butyricum (CB) RH2 on ceftriaxone-induced dysbacteriosis. To this purpose, BALB/c mice were exposed to ceftriaxone (400 mg/ml) or not (control) for 7 days, and administered a daily oral gavage of low-, and high-dose CB RH2 (108 and 1010 CFU/ml, respectively) for 2 weeks. CB RH2 altered the diversity of gut microbiota, changed the composition of gut microbiota in phylum and genus level, decreased the F/B ratio, and decreased the pro-inflammatory bacteria (Deferribacteres, Oscillibacter, Desulfovibrio, Mucispirillum and Parabacteroides) in ceftriaxone-treated mice. Additionally, CB RH2 improved colonic architecture and intestinal integrity by improving the mucous layer and the tight junction barrier. Furthermore, CB RH2 also mitigated intestinal inflammation through decreasing proinflammatory factors (TNF-α and COX-2) and increasing anti-inflammatory factors (IL-10). CB RH2 had direct effects on the expansion of CD4+ T cells in Peyer’s patches (PPs) in vitro, which in turn affected their immune response upon challenge with ceftriaxone. All these data suggested that CB RH2 possessed the ability to modulate the intestinal mucosal and systemic immune system in limiting intestinal alterations to relieve ceftriaxone-induced dysbacteriosis.
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Affiliation(s)
- Yuyuan Li
- Advanced Institute for Medical Sciences, Dalian Medical University, Dalian, China
| | - Man Liu
- College of Basic Medicine, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - He Liu
- College of Basic Medical Science, Dalian Medical University, Dalian, China
| | - Xue Sui
- Advanced Institute for Medical Sciences, Dalian Medical University, Dalian, China
| | - Yinhui Liu
- College of Basic Medical Science, Dalian Medical University, Dalian, China
| | - Xiaoqing Wei
- College of Basic Medical Science, Dalian Medical University, Dalian, China
| | - Chunzheng Liu
- College of Basic Medical Science, Dalian Medical University, Dalian, China
| | - Yiqin Cheng
- College of Basic Medical Science, Dalian Medical University, Dalian, China
| | - Weikang Ye
- College of Basic Medical Science, Dalian Medical University, Dalian, China
| | - Binbin Gao
- College of Basic Medical Science, Dalian Medical University, Dalian, China
| | - Xin Wang
- College of Basic Medical Science, Dalian Medical University, Dalian, China
| | - Qiao Lu
- College of Basic Medical Science, Dalian Medical University, Dalian, China
| | - Hao Cheng
- Marketing Department, Hangzhou Grand Biologic Pharmaceutical Inc., Hangzhou, China
| | - Lu Zhang
- Marketing Department, Hangzhou Grand Biologic Pharmaceutical Inc., Hangzhou, China
| | - Jieli Yuan
- College of Basic Medical Science, Dalian Medical University, Dalian, China
| | - Ming Li
- College of Basic Medical Science, Dalian Medical University, Dalian, China
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Plain A, Pan W, O’Neill D, Ure M, Beggs MR, Farhan M, Dimke H, Cordat E, Alexander RT. Claudin-12 Knockout Mice Demonstrate Reduced Proximal Tubule Calcium Permeability. Int J Mol Sci 2020; 21:ijms21062074. [PMID: 32197346 PMCID: PMC7139911 DOI: 10.3390/ijms21062074] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 03/11/2020] [Accepted: 03/15/2020] [Indexed: 01/13/2023] Open
Abstract
The renal proximal tubule (PT) is responsible for the reabsorption of approximately 65% of filtered calcium, primarily via a paracellular pathway. However, which protein(s) contribute this paracellular calcium pore is not known. The claudin family of tight junction proteins confers permeability properties to an epithelium. Claudin-12 is expressed in the kidney and when overexpressed in cell culture contributes paracellular calcium permeability (PCa). We therefore examined claudin-12 renal localization and its contribution to tubular paracellular calcium permeability. Claudin-12 null mice (KO) were generated by replacing the single coding exon with β-galactosidase from Escherichia coli. X-gal staining revealed that claudin-12 promoter activity colocalized with aquaporin-1, consistent with the expression in the PT. PTs were microperfused ex vivo and PCa was measured. PCa in PTs from KO mice was significantly reduced compared with WT mice. However, urinary calcium excretion was not different between genotypes, including those on different calcium containing diets. To assess downstream compensation, we examined renal mRNA expression. Claudin-14 expression, a blocker of PCa in the thick ascending limb (TAL), was reduced in the kidney of KO animals. Thus, claudin-12 is expressed in the PT, where it confers paracellular calcium permeability. In the absence of claudin-12, reduced claudin-14 expression in the TAL may compensate for reduced PT calcium reabsorption.
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Affiliation(s)
- Allein Plain
- Department of Physiology, The University of Alberta, Edmonton, AB T6J 2R7, Canada; (A.P.); (W.P.); (D.O.); (M.U.); (M.R.B.); (E.C.)
| | - Wanling Pan
- Department of Physiology, The University of Alberta, Edmonton, AB T6J 2R7, Canada; (A.P.); (W.P.); (D.O.); (M.U.); (M.R.B.); (E.C.)
| | - Deborah O’Neill
- Department of Physiology, The University of Alberta, Edmonton, AB T6J 2R7, Canada; (A.P.); (W.P.); (D.O.); (M.U.); (M.R.B.); (E.C.)
| | - Megan Ure
- Department of Physiology, The University of Alberta, Edmonton, AB T6J 2R7, Canada; (A.P.); (W.P.); (D.O.); (M.U.); (M.R.B.); (E.C.)
| | - Megan R. Beggs
- Department of Physiology, The University of Alberta, Edmonton, AB T6J 2R7, Canada; (A.P.); (W.P.); (D.O.); (M.U.); (M.R.B.); (E.C.)
- The Women’s & Children’s Health Research Institute, 11405-87 Avenue, Edmonton, AB T6G 1C9 Canada;
| | - Maikel Farhan
- The Women’s & Children’s Health Research Institute, 11405-87 Avenue, Edmonton, AB T6G 1C9 Canada;
- Department of Pediatrics, The University of Alberta, Edmonton, AB T6J 2R7, Canada
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, 5230 Odense, Denmark;
- Department of Nephrology, Odense University Hospital, 5000 Odense, Denmark
| | - Emmanuelle Cordat
- Department of Physiology, The University of Alberta, Edmonton, AB T6J 2R7, Canada; (A.P.); (W.P.); (D.O.); (M.U.); (M.R.B.); (E.C.)
| | - R. Todd Alexander
- Department of Physiology, The University of Alberta, Edmonton, AB T6J 2R7, Canada; (A.P.); (W.P.); (D.O.); (M.U.); (M.R.B.); (E.C.)
- The Women’s & Children’s Health Research Institute, 11405-87 Avenue, Edmonton, AB T6G 1C9 Canada;
- Department of Pediatrics, The University of Alberta, Edmonton, AB T6J 2R7, Canada
- Correspondence: ; Tel.: +1-(780)-248-5560
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Venugopal S, Anwer S, Szászi K. Claudin-2: Roles beyond Permeability Functions. Int J Mol Sci 2019; 20:ijms20225655. [PMID: 31726679 PMCID: PMC6888627 DOI: 10.3390/ijms20225655] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2019] [Revised: 11/08/2019] [Accepted: 11/09/2019] [Indexed: 12/12/2022] Open
Abstract
Claudin-2 is expressed in the tight junctions of leaky epithelia, where it forms cation-selective and water permeable paracellular channels. Its abundance is under fine control by a complex signaling network that affects both its synthesis and turnover in response to various environmental inputs. Claudin-2 expression is dysregulated in many pathologies including cancer, inflammation, and fibrosis. Claudin-2 has a key role in energy-efficient ion and water transport in the proximal tubules of the kidneys and in the gut. Importantly, strong evidence now also supports a role for this protein as a modulator of vital cellular events relevant to diseases. Signaling pathways that are overactivated in diseases can alter claudin-2 expression, and a good correlation exists between disease stage and claudin-2 abundance. Further, loss- and gain-of-function studies showed that primary changes in claudin-2 expression impact vital cellular processes such as proliferation, migration, and cell fate determination. These effects appear to be mediated by alterations in key signaling pathways. The specific mechanisms linking claudin-2 to these changes remain poorly understood, but adapters binding to the intracellular portion of claudin-2 may play a key role. Thus, dysregulation of claudin-2 may contribute to the generation, maintenance, and/or progression of diseases through both permeability-dependent and -independent mechanisms. The aim of this review is to provide an overview of the properties, regulation, and functions of claudin-2, with a special emphasis on its signal-modulating effects and possible role in diseases.
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King AJ, Siegel M, He Y, Nie B, Wang J, Koo-McCoy S, Minassian NA, Jafri Q, Pan D, Kohler J, Kumaraswamy P, Kozuka K, Lewis JG, Dragoli D, Rosenbaum DP, O'Neill D, Plain A, Greasley PJ, Jönsson-Rylander AC, Karlsson D, Behrendt M, Strömstedt M, Ryden-Bergsten T, Knöpfel T, Pastor Arroyo EM, Hernando N, Marks J, Donowitz M, Wagner CA, Alexander RT, Caldwell JS. Inhibition of sodium/hydrogen exchanger 3 in the gastrointestinal tract by tenapanor reduces paracellular phosphate permeability. Sci Transl Med 2019; 10:10/456/eaam6474. [PMID: 30158152 DOI: 10.1126/scitranslmed.aam6474] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 10/31/2017] [Accepted: 03/06/2018] [Indexed: 12/16/2022]
Abstract
Hyperphosphatemia is common in patients with chronic kidney disease and is increasingly associated with poor clinical outcomes. Current management of hyperphosphatemia with dietary restriction and oral phosphate binders often proves inadequate. Tenapanor, a minimally absorbed, small-molecule inhibitor of the sodium/hydrogen exchanger isoform 3 (NHE3), acts locally in the gastrointestinal tract to inhibit sodium absorption. Because tenapanor also reduces intestinal phosphate absorption, it may have potential as a therapy for hyperphosphatemia. We investigated the mechanism by which tenapanor reduces gastrointestinal phosphate uptake, using in vivo studies in rodents and translational experiments on human small intestinal stem cell-derived enteroid monolayers to model ion transport physiology. We found that tenapanor produces its effect by modulating tight junctions, which increases transepithelial electrical resistance (TEER) and reduces permeability to phosphate, reducing paracellular phosphate absorption. NHE3-deficient monolayers mimicked the phosphate phenotype of tenapanor treatment, and tenapanor did not affect TEER or phosphate flux in the absence of NHE3. Tenapanor also prevents active transcellular phosphate absorption compensation by decreasing the expression of NaPi2b, the major active intestinal phosphate transporter. In healthy human volunteers, tenapanor (15 mg, given twice daily for 4 days) increased stool phosphorus and decreased urinary phosphorus excretion. We determined that tenapanor reduces intestinal phosphate absorption predominantly through reduction of passive paracellular phosphate flux, an effect mediated exclusively via on-target NHE3 inhibition.
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Affiliation(s)
| | | | - Ying He
- Ardelyx Inc., Fremont, CA 94555, USA
| | | | - Ji Wang
- Ardelyx Inc., Fremont, CA 94555, USA
| | | | | | | | - Deng Pan
- Ardelyx Inc., Fremont, CA 94555, USA
| | | | | | | | | | | | | | - Debbie O'Neill
- University of Alberta, Edmonton, Alberta T6G 1C9, Canada
| | - Allein Plain
- University of Alberta, Edmonton, Alberta T6G 1C9, Canada
| | - Peter J Greasley
- Cardiovascular and Metabolic Disease (CVMD) Translational Medicine Unit, Early Clinical Development, Innovative Medicines and Early Development (IMED) Biotech Unit, AstraZeneca Gothenburg, 431 50 Mölndal, Sweden
| | | | - Daniel Karlsson
- Bioscience, CVMD, IMED Biotech Unit, AstraZeneca Gothenburg, 431 50 Mölndal, Sweden
| | - Margareta Behrendt
- Bioscience, CVMD, IMED Biotech Unit, AstraZeneca Gothenburg, 431 50 Mölndal, Sweden
| | - Maria Strömstedt
- Bioscience, CVMD, IMED Biotech Unit, AstraZeneca Gothenburg, 431 50 Mölndal, Sweden
| | | | - Thomas Knöpfel
- Institute of Physiology, University of Zurich and National Center of Competence in Research Kidney Control of Homeostasis, CH-8057 Zurich, Switzerland
| | - Eva M Pastor Arroyo
- Institute of Physiology, University of Zurich and National Center of Competence in Research Kidney Control of Homeostasis, CH-8057 Zurich, Switzerland
| | - Nati Hernando
- Institute of Physiology, University of Zurich and National Center of Competence in Research Kidney Control of Homeostasis, CH-8057 Zurich, Switzerland
| | - Joanne Marks
- Department of Neuroscience, Physiology and Pharmacology, University College London, Royal Free Campus, London NW3 2PF, UK
| | - Mark Donowitz
- Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich and National Center of Competence in Research Kidney Control of Homeostasis, CH-8057 Zurich, Switzerland
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Temporal Effects of Quercetin on Tight Junction Barrier Properties and Claudin Expression and Localization in MDCK II Cells. Int J Mol Sci 2019; 20:ijms20194889. [PMID: 31581662 PMCID: PMC6801663 DOI: 10.3390/ijms20194889] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 09/28/2019] [Accepted: 09/29/2019] [Indexed: 01/22/2023] Open
Abstract
: Kidney stones affect 10% of the population. Yet, there is relatively little known about how they form or how to prevent and treat them. The claudin family of tight junction proteins has been linked to the formation of kidney stones. The flavonoid quercetin has been shown to prevent kidney stone formation and to modify claudin expression in different models. Here we investigate the effect of quercetin on claudin expression and localization in MDCK II cells, a cation-selective cell line, derived from the proximal tubule. For this study, we focused our analyses on claudin family members that confer different tight junction properties: barrier-sealing (Cldn1, -3, and -7), cation-selective (Cldn2) or anion-selective (Cldn4). Our data revealed that quercetin's effects on the expression and localization of different claudins over time corresponded with changes in transepithelial resistance, which was measured continuously throughout the treatment. In addition, these effects appear to be independent of PI3K/AKT signaling, one of the pathways that is known to act downstream of quercetin. In conclusion, our data suggest that quercetin's effects on claudins result in a tighter epithelial barrier, which may reduce the reabsorption of sodium, calcium and water, thereby preventing the formation of a kidney stone.
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Dan Q, Shi Y, Rabani R, Venugopal S, Xiao J, Anwer S, Ding M, Speight P, Pan W, Alexander RT, Kapus A, Szászi K. Claudin-2 suppresses GEF-H1, RHOA, and MRTF, thereby impacting proliferation and profibrotic phenotype of tubular cells. J Biol Chem 2019; 294:15446-15465. [PMID: 31481470 DOI: 10.1074/jbc.ra118.006484] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Revised: 08/21/2019] [Indexed: 12/19/2022] Open
Abstract
The tight junctional pore-forming protein claudin-2 (CLDN-2) mediates paracellular Na+ and water transport in leaky epithelia and alters cancer cell proliferation. Previously, we reported that tumor necrosis factor-α time-dependently alters CLDN-2 expression in tubular epithelial cells. Here, we found a similar expression pattern in a mouse kidney injury model (unilateral ureteral obstruction), consisting of an initial increase followed by a drop in CLDN-2 protein expression. CLDN-2 silencing in LLC-PK1 tubular cells induced activation and phosphorylation of guanine nucleotide exchange factor H1 (GEF-H1), leading to Ras homolog family member A (RHOA) activation. Silencing of other claudins had no such effects, and re-expression of an siRNA-resistant CLDN-2 prevented RHOA activation, indicating specific effects of CLDN-2 on RHOA. Moreover, kidneys from CLDN-2 knockout mice had elevated levels of active RHOA. Of note, CLDN-2 silencing reduced LLC-PK1 cell proliferation and elevated expression of cyclin-dependent kinase inhibitor P27 (P27KIP1) in a GEF-H1/RHOA-dependent manner. P27KIP1 silencing abrogated the effects of CLDN-2 depletion on proliferation. CLDN-2 loss also activated myocardin-related transcription factor (MRTF), a fibrogenic RHOA effector, and elevated expression of connective tissue growth factor and smooth muscle actin. Finally, CLDN-2 down-regulation contributed to RHOA activation and smooth muscle actin expression induced by prolonged tumor necrosis factor-α treatment, because they were mitigated by re-expression of CLDN-2. Our results indicate that CLDN-2 suppresses GEF-H1/RHOA. CLDN-2 down-regulation, for example, by inflammation, can reduce proliferation and promote MRTF activation through RHOA. These findings suggest that the initial CLDN-2 elevation might aid epithelial regeneration, and CLDN-2 loss could contribute to fibrotic reprogramming.
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Affiliation(s)
- Qinghong Dan
- Keenan Research Centre for Biomedical Science at St. Michael's Hospital, University of Toronto, Ontario M5B 1T8, Canada
| | - Yixuan Shi
- Keenan Research Centre for Biomedical Science at St. Michael's Hospital, University of Toronto, Ontario M5B 1T8, Canada
| | - Razieh Rabani
- Keenan Research Centre for Biomedical Science at St. Michael's Hospital, University of Toronto, Ontario M5B 1T8, Canada
| | - Shruthi Venugopal
- Keenan Research Centre for Biomedical Science at St. Michael's Hospital, University of Toronto, Ontario M5B 1T8, Canada
| | - Jenny Xiao
- Keenan Research Centre for Biomedical Science at St. Michael's Hospital, University of Toronto, Ontario M5B 1T8, Canada
| | - Shaista Anwer
- Keenan Research Centre for Biomedical Science at St. Michael's Hospital, University of Toronto, Ontario M5B 1T8, Canada
| | - Mei Ding
- Keenan Research Centre for Biomedical Science at St. Michael's Hospital, University of Toronto, Ontario M5B 1T8, Canada
| | - Pam Speight
- Keenan Research Centre for Biomedical Science at St. Michael's Hospital, University of Toronto, Ontario M5B 1T8, Canada
| | - Wanling Pan
- Departments of Pediatrics and Physiology, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
| | - R Todd Alexander
- Departments of Pediatrics and Physiology, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
| | - András Kapus
- Keenan Research Centre for Biomedical Science at St. Michael's Hospital, University of Toronto, Ontario M5B 1T8, Canada.,Department of Surgery, University of Toronto, Ontario M5B 1T8, Canada
| | - Katalin Szászi
- Keenan Research Centre for Biomedical Science at St. Michael's Hospital, University of Toronto, Ontario M5B 1T8, Canada .,Department of Surgery, University of Toronto, Ontario M5B 1T8, Canada
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20
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The kidney anion exchanger 1 affects tight junction properties via claudin-4. Sci Rep 2019; 9:3099. [PMID: 30816203 PMCID: PMC6395713 DOI: 10.1038/s41598-019-39430-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 01/24/2019] [Indexed: 12/14/2022] Open
Abstract
In the renal collecting duct, intercalated cells regulate acid-base balance by effluxing protons through the v-H+-ATPase, and bicarbonate via apical pendrin or the basolateral kidney anion exchanger 1 (kAE1). Additionally, collecting duct cells play an essential role in transepithelial absorption of sodium and chloride. Expression of kAE1 in polarized MDCK I cells was previously shown to decrease trans-epithelial electrical resistance (TEER), suggesting a novel role for kAE1 in paracellular permeability. In our study, we not only confirmed that inducible expression of kAE1 in mIMCD3 cells decreased TEER but we also observed (i) increased epithelial absolute permeability to both sodium and chloride, and (ii) that this effect was dependent on kAE1 activity. Further, kAE1 regulated tight junction properties through the tight junction protein claudin-4, a protein with which it physically interacts and colocalizes. These findings unveil a novel interaction between the junctional protein claudin-4 and the kidney anion exchanger, which may be relevant to ion and/or pH homeostasis.
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22
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Amoozadeh Y, Dan Q, Anwer S, Huang HH, Barbieri V, Waheed F, Maishan M, Szászi K. Tumor Necrosis Factor-α Increases Claudin-1, 4, and 7 Expression in Tubular Cells: Role in Permeability Changes. J Cell Physiol 2017; 232:2210-2220. [DOI: 10.1002/jcp.25736] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 12/13/2016] [Indexed: 12/22/2022]
Affiliation(s)
- Yasaman Amoozadeh
- Keenan Research Centre for Biomedical Science of the St. Michael's Hospital; Ontario Canada
| | - Qinghong Dan
- Keenan Research Centre for Biomedical Science of the St. Michael's Hospital; Ontario Canada
| | - Shaista Anwer
- Keenan Research Centre for Biomedical Science of the St. Michael's Hospital; Ontario Canada
| | - Hsiao Han Huang
- Keenan Research Centre for Biomedical Science of the St. Michael's Hospital; Ontario Canada
| | - Vanessa Barbieri
- Keenan Research Centre for Biomedical Science of the St. Michael's Hospital; Ontario Canada
| | - Faiza Waheed
- Keenan Research Centre for Biomedical Science of the St. Michael's Hospital; Ontario Canada
| | - Mazharul Maishan
- Keenan Research Centre for Biomedical Science of the St. Michael's Hospital; Ontario Canada
- Department of Physiology; University of Toronto; Ontario Canada
| | - Katalin Szászi
- Keenan Research Centre for Biomedical Science of the St. Michael's Hospital; Ontario Canada
- Department of Surgery; University of Toronto; Ontario Canada
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23
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Kobayashi K, Tsugami Y, Matsunaga K, Oyama S, Kuki C, Kumura H. Prolactin and glucocorticoid signaling induces lactation-specific tight junctions concurrent with β-casein expression in mammary epithelial cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:2006-16. [DOI: 10.1016/j.bbamcr.2016.04.023] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 04/21/2016] [Accepted: 04/22/2016] [Indexed: 12/22/2022]
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Ahn C, Yang H, Lee D, An BS, Jeung EB. Placental claudin expression and its regulation by endogenous sex steroid hormones. Steroids 2015; 100:44-51. [PMID: 25982333 DOI: 10.1016/j.steroids.2015.05.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 05/04/2015] [Accepted: 05/06/2015] [Indexed: 12/17/2022]
Abstract
Tight junctions (TJs) form continuous intercellular contacts controlling the paracellular transportation across the cell-to-cell junction. TJ components include the peripheral protein zonula occludens-1 (ZO-1), junctional adhesion molecules (JAMs), and integral proteins such as occludin and claudins. Among the junction proteins, claudins play a major role in regulation of paracellular electrolyte transportation. This study explores the expression and distribution of tight junctions and their regulation during pregnancy. To study the regulation of claudin family, we examined expression of mouse placental tight junction proteins, including claudin-1 to -24, with real-time PCR and Western blotting and distribution of tight junction proteins with immunohistochemistry. Pregnant C57/BL6 mice were used in this study. The pregnant mice were divided into three groups depending on pregnant day (on days 12, 16, and 20 of gestation). Regarding the transcription levels, claudin-1, claudin-2, claudin-4, and claudin-5 expression levels were relatively high compared to other claudin family in all periods of pregnancy. Claudin-4 and 5 expressions, which reduce ion permeability, were increased over a period of time. However, claudin-2 expression, that is the responsive protein for a decrease in paracellular conductance, was decreased. Following this modulation of expression during mid-term pregnancy, we identified endogenous hormonal modulation of claudin family using estrogen receptor antagonist ICI 182,780 and progesterone receptor antagonist RU-486. After administration of ICI and RU-486, expression of claudin-4 mRNA and protein was increased. In addition, immunohistochemistry was performed to identify their localization for inferring permeability in placenta. Due to the function of claudins as effectors of ion transport at the end of regulatory pathways, they must be transducing proteins that modulate the function of claudins and thus link the physiologic inputs to the final effectors. This study will provide the claudin expressions and their localization in the mouse placenta, and their regulation by endogenous hormones. Taken together, the results of this study may contribute to assuming the roles and regulatory mechanism of these tight junction genes regarding maternal-fetal ion transportation in the placenta.
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Affiliation(s)
- Changhwan Ahn
- Laboratory of Veterinary Biochemistry and Molecular Biology, College of Veterinary Medicine, Chungbuk National University, Cheongju, Chungbuk 362-763, Republic of Korea
| | - Hyun Yang
- Laboratory of Veterinary Biochemistry and Molecular Biology, College of Veterinary Medicine, Chungbuk National University, Cheongju, Chungbuk 362-763, Republic of Korea
| | - Dongoh Lee
- Laboratory of Veterinary Biochemistry and Molecular Biology, College of Veterinary Medicine, Chungbuk National University, Cheongju, Chungbuk 362-763, Republic of Korea
| | - Beum-soo An
- Department of Biomaterials Sciences, College of Natural Resources & Life Science, Pusan National University, Miryang, Gyeongnam 627-706, Republic of Korea
| | - Eui-Bae Jeung
- Laboratory of Veterinary Biochemistry and Molecular Biology, College of Veterinary Medicine, Chungbuk National University, Cheongju, Chungbuk 362-763, Republic of Korea.
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Alexander RT, Rievaj J, Dimke H. Paracellular calcium transport across renal and intestinal epithelia. Biochem Cell Biol 2014; 92:467-80. [PMID: 25386841 DOI: 10.1139/bcb-2014-0061] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Calcium (Ca(2+)) is a key constituent in a myriad of physiological processes from intracellular signalling to the mineralization of bone. As a consequence, Ca(2+) is maintained within narrow limits when circulating in plasma. This is accomplished via regulated interplay between intestinal absorption, renal tubular reabsorption, and exchange with bone. Many studies have focused on the highly regulated active transcellular transport pathways for Ca(2+) from the duodenum of the intestine and the distal nephron of the kidney. However, comparatively little work has examined the molecular constituents creating the paracellular shunt across intestinal and renal epithelium, the transport pathway responsible for the majority of transepithelial Ca(2+) flux. More specifically, passive paracellular Ca(2+) absorption occurs across the majority of the intestine in addition to the renal proximal tubule and thick ascending limb of Henle's loop. Importantly, recent studies demonstrated that Ca(2+) transport through the paracellular shunt is significantly regulated. Therefore, we have summarized the evidence for different modes of paracellular Ca(2+) flux across renal and intestinal epithelia and highlighted recent molecular insights into both the mechanism of secondarily active paracellular Ca(2+) movement and the identity of claudins that permit the passage of Ca(2+) through the tight junction of these epithelia.
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Affiliation(s)
- R Todd Alexander
- a Department of Pediatrics, The University of Alberta, 4-585 Edmonton Clinic Health Academy, 11405 - 87 Ave, Edmonton, AB T6G 2R7, Canada
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Jennings P, Aschauer L, Wilmes A, Gstraunthaler G. Renal Cell Culture. METHODS IN PHARMACOLOGY AND TOXICOLOGY 2014. [DOI: 10.1007/978-1-4939-0521-8_4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Szaszi K, Amoozadeh Y. New Insights into Functions, Regulation, and Pathological Roles of Tight Junctions in Kidney Tubular Epithelium. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 308:205-71. [DOI: 10.1016/b978-0-12-800097-7.00006-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Strain-dependent augmentation of tight-junction barrier function in human primary epidermal keratinocytes by Lactobacillus and Bifidobacterium lysates. Appl Environ Microbiol 2013; 79:4887-94. [PMID: 23770906 DOI: 10.1128/aem.00982-13] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In this study, we investigated whether probiotic lysates can modify the tight-junction function of human primary keratinocytes. The keratinocytes were grown on cell culture inserts and treated with lysates from Bifidobacterium longum, Lactobacillus plantarum, Lactobacillus reuteri, Lactobacillus fermentum, or Lactobacillus rhamnosus GG. With the exception of L. fermentum (which decreased cell viability), all strains markedly enhanced tight-junction barrier function within 24 h, as assessed by measurements of transepithelial electrical resistance (TEER). However, B. longum and L. rhamnosus GG were the most efficacious, producing dose-dependent increases in resistance that were maintained for 4 days. These increases in TEER correlated with elevated expression of tight-junction protein components. Neutralization of Toll-like receptor 2 abolished both the increase in TEER and expression of tight-junction proteins induced by B. longum, but not L. rhamnosus GG. These data suggest that some bacterial strains increase tight-junction function via modulation of protein components but the different pathways involved may vary depending on the bacterial strain.
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Dimke H, Desai P, Borovac J, Lau A, Pan W, Alexander RT. Activation of the Ca(2+)-sensing receptor increases renal claudin-14 expression and urinary Ca(2+) excretion. Am J Physiol Renal Physiol 2013; 304:F761-9. [PMID: 23283989 DOI: 10.1152/ajprenal.00263.2012] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Kidney stones are a prevalent clinical condition imposing a large economic burden on the healthcare system. Hypercalciuria remains the major risk factor for development of a Ca(2+)-containing stone. The kidney's ability to alter Ca(2+) excretion in response to changes in serum Ca(2+) is in part mediated by the Ca(2+)-sensing receptor (CaSR). Recent studies revealed renal claudin-14 (Cldn14) expression localized to the thick ascending limb (TAL) and its expression to be regulated via the CaSR. We find that Cldn14 expression is increased by high dietary Ca(2+) intake and by elevated serum Ca(2+) levels induced by prolonged 1,25-dihydroxyvitamin D3 administration. Consistent with this, activation of the CaSR in vivo via administration of the calcimimetic cinacalcet hydrochloride led to a 40-fold increase in Cldn14 mRNA. Moreover, overexpression of Cldn14 in two separate cell culture models decreased paracellular Ca(2+) flux by preferentially decreasing cation permeability, thereby increasing transepithelial resistance. These data support the existence of a mechanism whereby activation of the CaSR in the TAL increases Cldn14 expression, which in turn blocks the paracellular reabsorption of Ca(2+). This molecular mechanism likely facilitates renal Ca(2+) losses in response to elevated serum Ca(2+). Moreover, dysregulation of the newly described CaSR-Cldn14 axis likely contributes to the development of hypercalciuria and kidney stones.
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Affiliation(s)
- Henrik Dimke
- Department of Physiology and Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
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