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Luo M, Liu Y, Nikolovska K, Riederer B, Patrucco E, Hofmann F, Seidler U. cGMP-dependent kinase 2, Na +/H + exchanger NHE3, and PDZ-adaptor NHERF2 co-assemble in apical membrane microdomains. Acta Physiol (Oxf) 2024; 240:e14125. [PMID: 38533975 DOI: 10.1111/apha.14125] [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: 10/12/2023] [Revised: 01/30/2024] [Accepted: 02/14/2024] [Indexed: 03/28/2024]
Abstract
AIM Trafficking, membrane retention, and signal-specific regulation of the Na+/H+ exchanger 3 (NHE3) are modulated by the Na+/H+ Exchanger Regulatory Factor (NHERF) family of PDZ-adapter proteins. This study explored the assembly of NHE3 and NHERF2 with the cGMP-dependent kinase II (cGKII) within detergent-resistant membrane microdomains (DRMs, "lipid rafts") during in vivo guanylate cycle C receptor (Gucy2c) activation in murine small intestine. METHODS Small intestinal brush border membranes (siBBMs) were isolated from wild type, NHE3-deficient, cGMP-kinase II-deficient, and NHERF2-deficient mice, after oral application of the heat-stable Escherichia coli toxin (STa) analog linaclotide. Lipid raft and non-raft fractions were separated by Optiprep density gradient centrifugation of Triton X-solubilized siBBMs. Confocal microscopy was performed to study NHE3 redistribution after linaclotide application in vivo. RESULTS In the WT siBBM, NHE3, NHERF2, and cGKII were strongly raft associated. The raft association of NHE3, but not of cGKII, was NHERF2 dependent. After linaclotide application to WT mice, lipid raft association of NHE3 decreased, that of cGKII increased, while that of NHERF2 did not change. NHE3 expression in the BBM shifted from a microvillar to a terminal web region. The linaclotide-induced decrease in NHE3 raft association and in microvillar abundance was abolished in cGKII-deficient mice, and strongly reduced in NHERF2-deficient mice. CONCLUSION NHE3, cGKII, and NHERF2 form a lipid raft-associated signal complex in the siBBM, which mediates the inhibition of salt and water absorption by Gucy2c activation. NHERF2 enhances the raft association of NHE3, which is essential for its close interaction with the exclusively raft-associated activated cGKII.
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Affiliation(s)
- Min Luo
- Department of Gastroenterology, Hepatology, Infectiology and Endocrinology, Hannover Medical School, Hannover, Germany
- Department of Infectious Diseases, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Yongjian Liu
- Department of Gastroenterology, Hepatology, Infectiology and Endocrinology, Hannover Medical School, Hannover, Germany
- Department of Endocrinology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Katerina Nikolovska
- Department of Gastroenterology, Hepatology, Infectiology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Brigitte Riederer
- Department of Gastroenterology, Hepatology, Infectiology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Enrico Patrucco
- Institut für Pharmakologie und Toxikologie, TU München, München, Germany
- Department of Molecular Biotechnology and Health Science, University of Torino, Torino, Italy
| | - Franz Hofmann
- Institut für Pharmakologie und Toxikologie, TU München, München, Germany
| | - Ursula Seidler
- Department of Gastroenterology, Hepatology, Infectiology and Endocrinology, Hannover Medical School, Hannover, Germany
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2
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Kalashyan M, Raghunathan K, Oller H, Bayer MT, Jimenez L, Roland JT, Kolobova E, Hagen SJ, Goldsmith JD, Shub MD, Goldenring JR, Kaji I, Thiagarajah JR. Patient-derived enteroids provide a platform for the development of therapeutic approaches in microvillus inclusion disease. J Clin Invest 2023; 133:e169234. [PMID: 37643022 PMCID: PMC10575727 DOI: 10.1172/jci169234] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 08/22/2023] [Indexed: 08/31/2023] Open
Abstract
Microvillus inclusion disease (MVID), caused by loss-of-function mutations in the motor protein myosin Vb (MYO5B), is a severe infantile disease characterized by diarrhea, malabsorption, and acid/base instability, requiring intensive parenteral support for nutritional and fluid management. Human patient-derived enteroids represent a model for investigation of monogenic epithelial disorders but are a rare resource from MVID patients. We developed human enteroids with different loss-of function MYO5B variants and showed that they recapitulated the structural changes found in native MVID enterocytes. Multiplex immunofluorescence imaging of patient duodenal tissues revealed patient-specific changes in localization of brush border transporters. Functional analysis of electrolyte transport revealed profound loss of Na+/H+ exchange (NHE) activity in MVID patient enteroids with near-normal chloride secretion. The chloride channel-blocking antidiarrheal drug crofelemer dose-dependently inhibited agonist-mediated fluid secretion. MVID enteroids exhibited altered differentiation and maturation versus healthy enteroids. γ-Secretase inhibition with DAPT recovered apical brush border structure and functional Na+/H+ exchange activity in MVID enteroids. Transcriptomic analysis revealed potential pathways involved in the rescue of MVID cells including serum/glucocorticoid-regulated kinase 2 (SGK2) and NHE regulatory factor 3 (NHERF3). These results demonstrate the utility of patient-derived enteroids for developing therapeutic approaches to MVID.
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Affiliation(s)
- Meri Kalashyan
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Krishnan Raghunathan
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Haley Oller
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Marie-Theres Bayer
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Lissette Jimenez
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
- Congenital Enteropathy Program, Boston Children’s Hospital, Boston, Massachusetts, USA
- PediCODE Consortium, as detailed in Supplemental Acknowledgments
| | - Joseph T. Roland
- Section of Surgical Sciences and
- Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Elena Kolobova
- Section of Surgical Sciences and
- Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Susan J. Hagen
- Department of Surgery, Division of Surgical Sciences, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA
| | - Jeffrey D. Goldsmith
- PediCODE Consortium, as detailed in Supplemental Acknowledgments
- Department of Pathology, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Mitchell D. Shub
- Department of Child Health, University of Arizona College of Medicine–Phoenix, and Division of Gastroenterology, Phoenix Children’s Hospital, Phoenix, Arizona, USA
| | - James R. Goldenring
- PediCODE Consortium, as detailed in Supplemental Acknowledgments
- Section of Surgical Sciences and
- Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Nashville VA Medical Center, Nashville, Tennessee, USA
| | - Izumi Kaji
- PediCODE Consortium, as detailed in Supplemental Acknowledgments
- Section of Surgical Sciences and
- Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Jay R. Thiagarajah
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
- Congenital Enteropathy Program, Boston Children’s Hospital, Boston, Massachusetts, USA
- PediCODE Consortium, as detailed in Supplemental Acknowledgments
- Harvard Digestive Disease Center, Boston, Massachusetts, USA
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3
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Rumpf M, Pautz S, Drebes B, Herberg FW, Müller HAJ. Microtubule-Associated Serine/Threonine (MAST) Kinases in Development and Disease. Int J Mol Sci 2023; 24:11913. [PMID: 37569286 PMCID: PMC10419289 DOI: 10.3390/ijms241511913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 07/17/2023] [Accepted: 07/19/2023] [Indexed: 08/13/2023] Open
Abstract
Microtubule-Associated Serine/Threonine (MAST) kinases represent an evolutionary conserved branch of the AGC protein kinase superfamily in the kinome. Since the discovery of the founding member, MAST2, in 1993, three additional family members have been identified in mammals and found to be broadly expressed across various tissues, including the brain, heart, lung, liver, intestine and kidney. The study of MAST kinases is highly relevant for unraveling the molecular basis of a wide range of different human diseases, including breast and liver cancer, myeloma, inflammatory bowel disease, cystic fibrosis and various neuronal disorders. Despite several reports on potential substrates and binding partners of MAST kinases, the molecular mechanisms that would explain their involvement in human diseases remain rather obscure. This review will summarize data on the structure, biochemistry and cell and molecular biology of MAST kinases in the context of biomedical research as well as organismal model systems in order to provide a current profile of this field.
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Affiliation(s)
- Marie Rumpf
- Department of Developmental Genetics, Institute of Biology, University of Kassel, 34321 Kassel, Germany; (M.R.)
| | - Sabine Pautz
- Department of Biochemistry, Institute of Biology, University of Kassel, 34321 Kassel, Germany
| | - Benedikt Drebes
- Department of Developmental Genetics, Institute of Biology, University of Kassel, 34321 Kassel, Germany; (M.R.)
| | - Friedrich W. Herberg
- Department of Biochemistry, Institute of Biology, University of Kassel, 34321 Kassel, Germany
| | - Hans-Arno J. Müller
- Department of Developmental Genetics, Institute of Biology, University of Kassel, 34321 Kassel, Germany; (M.R.)
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4
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Kalashyan M, Raghunathan K, Oller H, Theres MB, Jimenez L, Roland JT, Kolobova E, Hagen SJ, Goldsmith JD, Shub MD, Goldenring JR, Kaji I, Thiagarajah JR. Therapy Development for Microvillus Inclusion Disease using Patient-derived Enteroids. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.28.526036. [PMID: 36747680 PMCID: PMC9900906 DOI: 10.1101/2023.01.28.526036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Microvillus Inclusion Disease (MVID), caused by loss-of-function mutations in the motor protein Myosin Vb (MYO5B), is a severe infantile disease characterized by diarrhea, malabsorption, and acid-base instability, requiring intensive parenteral support for nutritional and fluid management. Human patient-derived enteroids represent a model for investigation of monogenic epithelial disorders but are a rare resource from MVID patients. We developed human enteroids with different loss-of function MYO5B variants and showed that they recapitulated the structural changes found in native MVID enterocytes. Multiplex Immunofluorescence imaging of patient duodenal tissues revealed patient-specific changes in localization of brush border transporters. Functional analysis of electrolyte transport revealed profound loss of Na + /H + exchange (NHE) activity in MVID patient enteroids with near-normal chloride secretion. The chloride channel-blocking anti-diarrheal drug, Crofelemer, dose-dependently inhibited agonist-mediated fluid secretion. MVID enteroids exhibited altered differentiation and maturation versus healthy enteroids. Inhibition of Notch signaling with the γ-secretase inhibitor, DAPT, recovered apical brush border structure and functional Na + /H + exchange activity in MVID enteroids. Transcriptomic analysis revealed potential pathways involved in the rescue of MVID cells including serum- and glucocorticoid-induced protein kinase 2 (SGK2), and NHE regulatory factor 3 (NHERF3). These results demonstrate the utility of patient-derived enteroids for developing therapeutic approaches to MVID. Conflict-of-interest statement The authors have declared that no conflict of interest exists.
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Affiliation(s)
- Meri Kalashyan
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital; Harvard Medical School, Boston, MA
| | - Krishnan Raghunathan
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital; Harvard Medical School, Boston, MA
| | - Haley Oller
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital; Harvard Medical School, Boston, MA
| | - Marie-Bayer Theres
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital; Harvard Medical School, Boston, MA
| | - Lissette Jimenez
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital; Harvard Medical School, Boston, MA
- Congenital Enteropathy Program, Boston Children’s Hospital, Boston, MA
- PediCoDE Consortium
| | - Joseph T. Roland
- Section of Surgical Sciences, Vanderbilt University Medical Center, Nashville, Tennessee
- Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Elena Kolobova
- Section of Surgical Sciences, Vanderbilt University Medical Center, Nashville, Tennessee
- Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Susan J Hagen
- Department of Surgery, Division of Surgical Sciences, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA
| | - Jeffrey D. Goldsmith
- Department of Pathology, Boston Children’s Hospital; Harvard Medical School, Boston, MA
- PediCoDE Consortium
| | - Mitchell D. Shub
- Department of Child Health University of Arizona College of Medicine-Phoenix and Division of Gastroenterology, Phoenix Children’s
| | - James R. Goldenring
- Section of Surgical Sciences, Vanderbilt University Medical Center, Nashville, Tennessee
- Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, Tennessee
- Nashville VA Medical Center, Nashville, TN
- PediCoDE Consortium
| | - Izumi Kaji
- Section of Surgical Sciences, Vanderbilt University Medical Center, Nashville, Tennessee
- Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, Tennessee
- PediCoDE Consortium
| | - Jay R. Thiagarajah
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital; Harvard Medical School, Boston, MA
- Congenital Enteropathy Program, Boston Children’s Hospital, Boston, MA
- Harvard Digestive Disease Center, Boston MA
- PediCoDE Consortium
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5
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Delgado-Bermúdez A, Yeste M, Bonet S, Pinart E. A Review on the Role of Bicarbonate and Proton Transporters during Sperm Capacitation in Mammals. Int J Mol Sci 2022; 23:ijms23116333. [PMID: 35683013 PMCID: PMC9180951 DOI: 10.3390/ijms23116333] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 06/01/2022] [Accepted: 06/05/2022] [Indexed: 12/14/2022] Open
Abstract
Alkalinization of sperm cytosol is essential for plasma membrane hyperpolarization, hyperactivation of motility, and acrosomal exocytosis during sperm capacitation in mammals. The plasma membrane of sperm cells contains different ion channels implicated in the increase of internal pH (pHi) by favoring either bicarbonate entrance or proton efflux. Bicarbonate transporters belong to the solute carrier families 4 (SLC4) and 26 (SLC26) and are currently grouped into Na+/HCO3− transporters and Cl−/HCO3− exchangers. Na+/HCO3− transporters are reported to be essential for the initial and fast entrance of HCO3− that triggers sperm capacitation, whereas Cl−/HCO3− exchangers are responsible for the sustained HCO3− entrance which orchestrates the sequence of changes associated with sperm capacitation. Proton efflux is required for the fast alkalinization of capacitated sperm cells and the activation of pH-dependent proteins; according to the species, this transport can be mediated by Na+/H+ exchangers (NHE) belonging to the SLC9 family and/or voltage-gated proton channels (HVCN1). Herein, we discuss the involvement of each of these channels in sperm capacitation and the acrosome reaction.
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Affiliation(s)
- Ariadna Delgado-Bermúdez
- Biotechnology of Animal and Human Reproduction (TechnoSperm), Institute of Food and Agricultural Technology, University of Girona, ES-17003 Girona, Spain; (A.D.-B.); (M.Y.); (S.B.)
- Unit of Cell Biology, Department of Biology, Faculty of Sciences, University of Girona, ES-17003 Girona, Spain
| | - Marc Yeste
- Biotechnology of Animal and Human Reproduction (TechnoSperm), Institute of Food and Agricultural Technology, University of Girona, ES-17003 Girona, Spain; (A.D.-B.); (M.Y.); (S.B.)
- Unit of Cell Biology, Department of Biology, Faculty of Sciences, University of Girona, ES-17003 Girona, Spain
- Catalan Institution for Research and Advanced Studies (ICREA), ES-08010 Barcelona, Spain
| | - Sergi Bonet
- Biotechnology of Animal and Human Reproduction (TechnoSperm), Institute of Food and Agricultural Technology, University of Girona, ES-17003 Girona, Spain; (A.D.-B.); (M.Y.); (S.B.)
- Unit of Cell Biology, Department of Biology, Faculty of Sciences, University of Girona, ES-17003 Girona, Spain
| | - Elisabeth Pinart
- Biotechnology of Animal and Human Reproduction (TechnoSperm), Institute of Food and Agricultural Technology, University of Girona, ES-17003 Girona, Spain; (A.D.-B.); (M.Y.); (S.B.)
- Unit of Cell Biology, Department of Biology, Faculty of Sciences, University of Girona, ES-17003 Girona, Spain
- Correspondence: ; Tel.: +34-972-419-514
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6
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Nikolovska K, Seidler UE, Stock C. The Role of Plasma Membrane Sodium/Hydrogen Exchangers in Gastrointestinal Functions: Proliferation and Differentiation, Fluid/Electrolyte Transport and Barrier Integrity. Front Physiol 2022; 13:899286. [PMID: 35665228 PMCID: PMC9159811 DOI: 10.3389/fphys.2022.899286] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 04/19/2022] [Indexed: 12/11/2022] Open
Abstract
The five plasma membrane Na+/H+ exchanger (NHE) isoforms in the gastrointestinal tract are characterized by distinct cellular localization, tissue distribution, inhibitor sensitivities, and physiological regulation. NHE1 (Slc9a1) is ubiquitously expressed along the gastrointestinal tract in the basolateral membrane of enterocytes, but so far, an exclusive role for NHE1 in enterocyte physiology has remained elusive. NHE2 (Slc9a2) and NHE8 (Slc9a8) are apically expressed isoforms with ubiquitous distribution along the colonic crypt axis. They are involved in pHi regulation of intestinal epithelial cells. Combined use of a knockout mouse model, intestinal organoid technology, and specific inhibitors revealed previously unrecognized actions of NHE2 and NHE8 in enterocyte proliferation and differentiation. NHE3 (Slc9a3), expressed in the apical membrane of differentiated intestinal epithelial cells, functions as the predominant nutrient-independent Na+ absorptive mechanism in the gut. The new selective NHE3 inhibitor (Tenapanor) allowed discovery of novel pathophysiological and drug-targetable NHE3 functions in cystic-fibrosis associated intestinal obstructions. NHE4, expressed in the basolateral membrane of parietal cells, is essential for parietal cell integrity and acid secretory function, through its role in cell volume regulation. This review focuses on the expression, regulation and activity of the five plasma membrane Na+/H+ exchangers in the gastrointestinal tract, emphasizing their role in maintaining intestinal homeostasis, or their impact on disease pathogenesis. We point to major open questions in identifying NHE interacting partners in central cellular pathways and processes and the necessity of determining their physiological role in a system where their endogenous expression/activity is maintained, such as organoids derived from different parts of the gastrointestinal tract.
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7
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Whittamore JM, Hatch M. Oxalate Flux Across the Intestine: Contributions from Membrane Transporters. Compr Physiol 2021; 12:2835-2875. [PMID: 34964122 DOI: 10.1002/cphy.c210013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Epithelial oxalate transport is fundamental to the role occupied by the gastrointestinal (GI) tract in oxalate homeostasis. The absorption of dietary oxalate, together with its secretion into the intestine, and degradation by the gut microbiota, can all influence the excretion of this nonfunctional terminal metabolite in the urine. Knowledge of the transport mechanisms is relevant to understanding the pathophysiology of hyperoxaluria, a risk factor in kidney stone formation, for which the intestine also offers a potential means of treatment. The following discussion presents an expansive review of intestinal oxalate transport. We begin with an overview of the fate of oxalate, focusing on the sources, rates, and locations of absorption and secretion along the GI tract. We then consider the mechanisms and pathways of transport across the epithelial barrier, discussing the transcellular, and paracellular components. There is an emphasis on the membrane-bound anion transporters, in particular, those belonging to the large multifunctional Slc26 gene family, many of which are expressed throughout the GI tract, and we summarize what is currently known about their participation in oxalate transport. In the final section, we examine the physiological stimuli proposed to be involved in regulating some of these pathways, encompassing intestinal adaptations in response to chronic kidney disease, metabolic acid-base disorders, obesity, and following gastric bypass surgery. There is also an update on research into the probiotic, Oxalobacter formigenes, and the basis of its unique interaction with the gut epithelium. © 2021 American Physiological Society. Compr Physiol 11:1-41, 2021.
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Affiliation(s)
- Jonathan M Whittamore
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Marguerite Hatch
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, Florida, USA
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8
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Larsen MB, Choi JJ, Wang X, Myerburg MM, Frizzell RA, Bertrand CA. Separating the contributions of SLC26A9 and CFTR to anion secretion in primary human bronchial epithelia. Am J Physiol Lung Cell Mol Physiol 2021; 321:L1147-L1160. [PMID: 34668421 PMCID: PMC8715023 DOI: 10.1152/ajplung.00563.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 10/01/2021] [Accepted: 10/15/2021] [Indexed: 11/22/2022] Open
Abstract
Aberrant anion secretion across the bronchial epithelium is associated with airway disease, most notably in cystic fibrosis. Although the cystic fibrosis transmembrane conductance regulator (CFTR) is recognized as the primary source of airway anion secretion, alternative anion transport mechanisms play a contributing role. An alternative anion transporter of growing interest is SLC26A9, a constitutively active chloride channel that has been shown to interact with CFTR and may also contribute to bicarbonate secretion. Interest in SLC26A9 has been fueled by genome-wide association studies that suggest it is a significant modifier of CF disease severity. Despite this growing evidence that SLC26A9 plays an important role in the airway, its presence and function in bronchial epithelia remain poorly understood, in part, because its activity is difficult to separate from the activity of CFTR. Here, we present results using primary human bronchial epithelia (HBE) from multiple patient sources to confirm that SLC26A9 mRNA is present in HBE and that its constitutive channel activity is unaffected by knockdown of CFTR. Furthermore, SLC26A9 and CFTR show differential responses to common inhibitors of anion secretion. Finally, we assess the impact of bicarbonate on the activity of SLC26A9 and CFTR. These results confirm that SLC26A9 is the primary source of constitutive anion secretion across HBE, and should inform future studies focused on activation of SLC26A9 as an alternative anion channel in CF. These results should provide a strong foundation to investigate how single-nucleotide polymorphisms in SLC26A9 modulate airway disease.
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Affiliation(s)
- Mads B Larsen
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Jeannie J Choi
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Xiaohui Wang
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Michael M Myerburg
- Department of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Raymond A Frizzell
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Carol A Bertrand
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
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9
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Stephens CE, Whittamore JM, Hatch M. The role of NHE3 (Slc9a3) in oxalate and sodium transport by mouse intestine and regulation by cAMP. Physiol Rep 2021; 9:e14828. [PMID: 33904662 PMCID: PMC8077127 DOI: 10.14814/phy2.14828] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 03/01/2021] [Accepted: 03/09/2021] [Indexed: 12/14/2022] Open
Abstract
Intestinal oxalate transport involves Cl−/HCO3− exchangers but how this transport is regulated is not currently known. NHE3 (Slc9a3), an apical Na+/H+ exchanger, is an established target for regulation of electroneutral NaCl absorption working in concert with Cl−/HCO3− exchangers. To test whether NHE3 could be involved in regulation of intestinal oxalate transport and renal oxalate handling we compared urinary oxalate excretion rates and intestinal transepithelial fluxes of 14C‐oxalate and 22Na+ between NHE3 KO and wild‐type (WT) mice. NHE3 KO kidneys had lower creatinine clearance suggesting reduced GFR, but urinary oxalate excretion rates (µmol/24 h) were similar compared to the WT but doubled when expressed as a ratio of creatinine. Intestinal transepithelial fluxes of 14C‐oxalate and 22Na+ were measured in the distal ileum, cecum, and distal colon. The absence of NHE3 did not affect basal net transport rates of oxalate or sodium across any intestinal section examined. Stimulation of intracellular cAMP with forskolin (FSK) and 3‐isobutyl‐1‐methylxanthine (IBMX) led to an increase in net oxalate secretion in the WT distal ileum and cecum and inhibition of sodium absorption in the cecum and distal colon. In NHE3 KO cecum, cAMP stimulation of oxalate secretion was impaired suggesting the possibility of a role for NHE3 in this process. Although, there is little evidence for a role of NHE3 in basal intestinal oxalate fluxes, NHE3 may be important for cAMP stimulation of oxalate in the cecum and for renal handling of oxalate.
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Affiliation(s)
- Christine E Stephens
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Jonathan M Whittamore
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Marguerite Hatch
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, USA
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10
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Que T, Wang H, Yang W, Wu J, Hou C, Pei S, Wu Q, Li LM, Wei S, Xie X, Huang H, Chen P, Huang Y, Wu A, He M, Nong D, Wei X, Wu J, Nong R, Huang N, Zhou Q, Lin Y, Lu T, Wei Y, Li S, Yao J, Zhong Y, Qin H, Tan L, Li Y, Li W, Liu T, Liu S, Yu Y, Qiu H, Jiang Y, Li Y, Liu Z, Huang CM, Hu Y. The reference genome and transcriptome of the limestone langur, Trachypithecus leucocephalus, reveal expansion of genes related to alkali tolerance. BMC Biol 2021; 19:67. [PMID: 33832502 PMCID: PMC8034193 DOI: 10.1186/s12915-021-00998-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 03/05/2021] [Indexed: 01/13/2023] Open
Abstract
Background Trachypithecus leucocephalus, the white-headed langur, is a critically endangered primate that is endemic to the karst mountains in the southern Guangxi province of China. Studying the genomic and transcriptomic mechanisms underlying its local adaptation could help explain its persistence within a highly specialized ecological niche. Results In this study, we used PacBio sequencing and optical assembly and Hi-C analysis to create a high-quality de novo assembly of the T. leucocephalus genome. Annotation and functional enrichment revealed many genes involved in metabolism, transport, and homeostasis, and almost all of the positively selected genes were related to mineral ion binding. The transcriptomes of 12 tissues from three T. leucocephalus individuals showed that the great majority of genes involved in mineral absorption and calcium signaling were expressed, and their gene families were significantly expanded. For example, FTH1 primarily functions in iron storage and had 20 expanded copies. Conclusions These results increase our understanding of the evolution of alkali tolerance and other traits necessary for the persistence of T. leucocephalus within an ecologically unique limestone karst environment.
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Affiliation(s)
- Tengcheng Que
- Terrestrial Wildlife Rescue and Epidemic Diseases Surveillance Center of Guangxi, Nanning, Guangxi, 530003, China
| | - Huifeng Wang
- Department of Biochemistry and Molecular Biology, School of Pre-Clinical Medicine, Guangxi Medical University, Nanning, Guangxi, 530021, China
| | - Weifei Yang
- Annoroad Gene Technology, Beijing, 100176, China
| | - Jianbao Wu
- Guangxi Chongzuo white headed langur national nature reserve, Chongzuo, Guangxi, 532200, China
| | - Chenyang Hou
- School of Information and Management, Guangxi Medical University, Nanning, Guangxi, 530021, China
| | - Surui Pei
- Annoroad Gene Technology, Beijing, 100176, China
| | - Qunying Wu
- Department of Biochemistry and Molecular Biology, School of Pre-Clinical Medicine, Guangxi Medical University, Nanning, Guangxi, 530021, China
| | - Liu Ming Li
- Guangxi Reproductive Medical Research Center, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, 530021, China
| | - Shilu Wei
- Life Sciences Institute, Guangxi Medical University, Nanning, Guangxi, 530021, China
| | - Xing Xie
- Life Sciences Institute, Guangxi Medical University, Nanning, Guangxi, 530021, China
| | - Hongli Huang
- Life Sciences Institute, Guangxi Medical University, Nanning, Guangxi, 530021, China
| | - Panyu Chen
- Terrestrial Wildlife Rescue and Epidemic Diseases Surveillance Center of Guangxi, Nanning, Guangxi, 530003, China
| | - Yiming Huang
- Center for Genomic and Personalized Medicine, Guangxi Medical University, Nanning, Guangxi, 530021, China
| | - Aiqiong Wu
- Terrestrial Wildlife Rescue and Epidemic Diseases Surveillance Center of Guangxi, Nanning, Guangxi, 530003, China
| | - Meihong He
- Terrestrial Wildlife Rescue and Epidemic Diseases Surveillance Center of Guangxi, Nanning, Guangxi, 530003, China
| | - Dengpan Nong
- Terrestrial Wildlife Rescue and Epidemic Diseases Surveillance Center of Guangxi, Nanning, Guangxi, 530003, China
| | - Xiao Wei
- Guangxi Chongzuo white headed langur national nature reserve, Chongzuo, Guangxi, 532200, China
| | - Junyi Wu
- Nanning Animal Zoo, Nanning, Guangxi, 530021, China
| | - Ru Nong
- Nanning Animal Zoo, Nanning, Guangxi, 530021, China
| | - Ning Huang
- Nanning Animal Zoo, Nanning, Guangxi, 530021, China
| | - Qingniao Zhou
- Department of Biochemistry and Molecular Biology, School of Pre-Clinical Medicine, Guangxi Medical University, Nanning, Guangxi, 530021, China
| | - Yaowang Lin
- Department of Biochemistry and Molecular Biology, School of Pre-Clinical Medicine, Guangxi Medical University, Nanning, Guangxi, 530021, China
| | - Tingxi Lu
- School of Information and Management, Guangxi Medical University, Nanning, Guangxi, 530021, China
| | - Yongjie Wei
- Terrestrial Wildlife Rescue and Epidemic Diseases Surveillance Center of Guangxi, Nanning, Guangxi, 530003, China
| | - Shousheng Li
- Terrestrial Wildlife Rescue and Epidemic Diseases Surveillance Center of Guangxi, Nanning, Guangxi, 530003, China
| | - Jianglong Yao
- Terrestrial Wildlife Rescue and Epidemic Diseases Surveillance Center of Guangxi, Nanning, Guangxi, 530003, China
| | - Yanli Zhong
- Terrestrial Wildlife Rescue and Epidemic Diseases Surveillance Center of Guangxi, Nanning, Guangxi, 530003, China
| | - Huayong Qin
- Terrestrial Wildlife Rescue and Epidemic Diseases Surveillance Center of Guangxi, Nanning, Guangxi, 530003, China
| | - Luohao Tan
- Terrestrial Wildlife Rescue and Epidemic Diseases Surveillance Center of Guangxi, Nanning, Guangxi, 530003, China
| | - Yingjiao Li
- Terrestrial Wildlife Rescue and Epidemic Diseases Surveillance Center of Guangxi, Nanning, Guangxi, 530003, China
| | - Weidong Li
- Life Sciences Institute, Guangxi Medical University, Nanning, Guangxi, 530021, China
| | - Tao Liu
- Annoroad Gene Technology, Beijing, 100176, China
| | - Sanyang Liu
- Annoroad Gene Technology, Beijing, 100176, China
| | - Yongyi Yu
- Annoroad Gene Technology, Beijing, 100176, China
| | - Hong Qiu
- Annoroad Gene Technology, Beijing, 100176, China
| | - Yonghua Jiang
- Center for Genomic and Personalized Medicine, Guangxi Medical University, Nanning, Guangxi, 530021, China
| | - Youcheng Li
- Life Sciences Institute, Guangxi Medical University, Nanning, Guangxi, 530021, China
| | - Zhijin Liu
- College of Life Sciences, Capital Normal University, Beijing, 100048, China
| | - Cheng Ming Huang
- College of Life Sciences, Capital Normal University, Beijing, 100048, China.
| | - Yanling Hu
- Department of Biochemistry and Molecular Biology, School of Pre-Clinical Medicine, Guangxi Medical University, Nanning, Guangxi, 530021, China. .,Life Sciences Institute, Guangxi Medical University, Nanning, Guangxi, 530021, China. .,Center for Genomic and Personalized Medicine, Guangxi Medical University, Nanning, Guangxi, 530021, China.
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11
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Yu Q. Slc26a3 (DRA) in the Gut: Expression, Function, Regulation, Role in Infectious Diarrhea and Inflammatory Bowel Disease. Inflamm Bowel Dis 2021; 27:575-584. [PMID: 32989468 DOI: 10.1093/ibd/izaa256] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Indexed: 12/12/2022]
Abstract
BACKGROUND The transport of transepithelial Cl- and HCO3- is crucial for the function of the intestinal epithelium and maintains the acid-based homeostasis. Slc26a3 (DRA), as a key chloride-bicarbonate exchanger protein in the intestinal epithelial luminal membrane, participates in the electroneutral NaCl absorption of intestine, together with Na+/H+ exchangers. Increasing recent evidence supports the essential role of decreased DRA function or expression in infectious diarrhea and inflammatory bowel disease (IBD). METHOD In this review, we give an overview of the current knowledge of Slc26a3, including its cloning and expression, function, roles in infectious diarrhea and IBD, and mechanisms of actions. A better understanding of the physiological and pathophysiological relevance of Slc26a3 in infectious diarrhea and IBD may reveal novel targets for future therapy. CONCLUSION Understanding the physiological function, regulatory interactions, and the potential mechanisms of Slc26a3 in the pathophysiology of infectious diarrhea and IBD will define novel therapeutic approaches in future.
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Affiliation(s)
- Qin Yu
- Department of Gastroenterology, Tongji Hospital, Huazhong University of Science and Technology, Wuhan City, China
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12
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Deciphering ion transporters, kinases and PDZ-adaptor molecules that mediate guanylate cyclase C agonist-dependent intestinal fluid loss in vivo. Biochem Pharmacol 2020; 178:114040. [DOI: 10.1016/j.bcp.2020.114040] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 05/13/2020] [Indexed: 01/12/2023]
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13
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Bannert K, Berlin P, Reiner J, Lemcke H, David R, Engelmann R, Lamprecht G. SNX27 regulates DRA activity and mediates its direct recycling by PDZ-interaction in early endosomes at the apical pole of Caco2 cells. Am J Physiol Gastrointest Liver Physiol 2020; 318:G854-G869. [PMID: 32116023 DOI: 10.1152/ajpgi.00374.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
DRA (downregulated in adenoma, SLC26A3) and NHE3 (Na+/H+ exchanger 3, SLC9A3) together mediate intestinal electroneutral NaCl absorption. Both transporters contain PDZ (postsynaptic density 95, disc large, zonula occludens 1) binding motifs and interact with PDZ adaptor proteins regulating their activity and recycling. SNX27 (sorting nexin 27) contains a PDZ domain and is involved in the recycling of cargo proteins including NHE3. The interaction of SNX27 with DRA and its potential role for the activity and recycling of DRA have been evaluated in this study. SNX27 specifically interacts with DRA via its PDZ domain. The knockdown (KD) of SNX27 reduced DRA activity by 50% but was not accompanied by a decrease of DRA surface expression. This indicates that DRA is trafficked to specific functional domains in the plasma membrane in which DRA is particularly active. Consistently, the disruption of lipid raft integrity by methyl-β-cyclodextrin has an inhibitory effect on DRA activity that was strongly reduced after SNX27 KD. In differentiated intestinal Caco2 cells, superresolution microscopy and a novel quantitative axial approach revealed that DRA and SNX27 colocalize in rab5-positive early endosomes at the apical pole. SNX27 regulates the activity of DRA in the apical plasma membrane through binding with its PDZ domain. This interaction occurs in rab5-positive early endosomes at the apical pole of differentiated intestinal Caco2 cells. SNX27 is involved in the direct recycling of DRA to the plasma membrane where it is inserted into lipid rafts facilitating increased activity.NEW & NOTEWORTHY SNX27 has a PDZ domain and is involved in the regulation and recycling of transmembrane proteins. The role of SNX27 on the activity and recycling of the intestinal Cl-/HCO3- exchanger DRA has not yet been studied. This study shows that SNX27 directly interacts with DRA in early endosomes at the apical pole of intestinal Caco2 cells and mediates its direct recycling to facilitate high activity in lipid rafts in the apical plasma membrane.
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Affiliation(s)
- Karen Bannert
- Department of Gastroenterology and Endocrinology, Center for Internal Medicine, Rostock University Medical Center, Rostock, Germany
| | - Peggy Berlin
- Department of Gastroenterology and Endocrinology, Center for Internal Medicine, Rostock University Medical Center, Rostock, Germany
| | - Johannes Reiner
- Department of Gastroenterology and Endocrinology, Center for Internal Medicine, Rostock University Medical Center, Rostock, Germany
| | - Heiko Lemcke
- Department of Cardiac Surgery, Rostock University Medical Center, Rostock, Germany.,Department Life, Light and Matter, University of Rostock, Rostock, Germany
| | - Robert David
- Department of Cardiac Surgery, Rostock University Medical Center, Rostock, Germany.,Department Life, Light and Matter, University of Rostock, Rostock, Germany
| | - Robby Engelmann
- Institute of Immunology, Rostock University Medical Center, Rostock, Germany
| | - Georg Lamprecht
- Department of Gastroenterology and Endocrinology, Center for Internal Medicine, Rostock University Medical Center, Rostock, Germany
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14
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Antihypertensive and Renal Mechanisms of SGLT2 (Sodium-Glucose Linked Transporter 2) Inhibitors. Hypertension 2020; 75:894-901. [DOI: 10.1161/hypertensionaha.119.11684] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Empaglifolzin, canagliflozin, and dapagliflozin are SGLT2 (sodium-glucose linked transporter type 2) inhibitors for treatment of type 2 diabetes mellitus that also reduce blood pressure, mortality, and cardiovascular disease and slow the loss of glomerular filtration rate. SGLT2 inhibitors inhibit the coupled reabsorption of sodium and glucose from the proximal tubules, thereby increasing renal glucose and sodium excretion, but they have more widespread renal effects, including inhibition of the sodium:proton exchanger. They increase the delivery of sodium to the loop of Henle and can thereby activate the tubuloglomerular feedback response to correct glomerular hyperfiltration. There are multiple potential mechanisms whereby these drugs lower blood pressure and preserve kidney function that are the focus of this review.
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15
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Pedersen SF, Counillon L. The SLC9A-C Mammalian Na +/H + Exchanger Family: Molecules, Mechanisms, and Physiology. Physiol Rev 2019; 99:2015-2113. [PMID: 31507243 DOI: 10.1152/physrev.00028.2018] [Citation(s) in RCA: 103] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Na+/H+ exchangers play pivotal roles in the control of cell and tissue pH by mediating the electroneutral exchange of Na+ and H+ across cellular membranes. They belong to an ancient family of highly evolutionarily conserved proteins, and they play essential physiological roles in all phyla. In this review, we focus on the mammalian Na+/H+ exchangers (NHEs), the solute carrier (SLC) 9 family. This family of electroneutral transporters constitutes three branches: SLC9A, -B, and -C. Within these, each isoform exhibits distinct tissue expression profiles, regulation, and physiological roles. Some of these transporters are highly studied, with hundreds of original articles, and some are still only rudimentarily understood. In this review, we present and discuss the pioneering original work as well as the current state-of-the-art research on mammalian NHEs. We aim to provide the reader with a comprehensive view of core knowledge and recent insights into each family member, from gene organization over protein structure and regulation to physiological and pathophysiological roles. Particular attention is given to the integrated physiology of NHEs in the main organ systems. We provide several novel analyses and useful overviews, and we pinpoint main remaining enigmas, which we hope will inspire novel research on these highly versatile proteins.
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Affiliation(s)
- S F Pedersen
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark; and Université Côte d'Azur, CNRS, Laboratoire de Physiomédecine Moléculaire, LP2M, France, and Laboratories of Excellence Ion Channel Science and Therapeutics, Nice, France
| | - L Counillon
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark; and Université Côte d'Azur, CNRS, Laboratoire de Physiomédecine Moléculaire, LP2M, France, and Laboratories of Excellence Ion Channel Science and Therapeutics, Nice, France
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16
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Pera T, Tompkins E, Katz M, Wang B, Deshpande DA, Weinman EJ, Penn RB. Specificity of NHERF1 regulation of GPCR signaling and function in human airway smooth muscle. FASEB J 2019; 33:9008-9016. [PMID: 31042404 PMCID: PMC6662985 DOI: 10.1096/fj.201900323r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 04/08/2019] [Indexed: 12/21/2022]
Abstract
Na+/H+ exchanger regulatory factor 1 (NHERF1; also known as ezrin-radixin-moesin-binding phosphoprotein 50) is a PSD-95, disc large, zona occludens-1 adapter that acts as a scaffold for signaling complexes and cytoskeletal-plasma membrane interactions. NHERF1 is crucial to β-2-adrenoceptor (β2AR)-mediated activation of cystic fibrosis transmembrane conductance regulator (CFTR) in epithelial cells, and NHERF1 has been proposed to mediate the recycling of internalized β2AR back to the cell membrane. In the current study, we assessed the role of NHERF1 in regulating cAMP-mediated signaling and immunomodulatory functions in airway smooth muscle (ASM). NHERF1 knockdown attenuated the induction of (protein kinase A) phospho-vasodilator-stimulated phosphoprotein (p-VASP) by isoproterenol (ISO), prostaglandin E2 (PGE2), or forskolin (FSK) as well as the induction of p-heat shock protein 20 after 4 h of stimulation with ISO and FSK. NHERF1 knockdown fully abrogated the ISO-, PGE2-, and FSK-induced IL-6 gene expression and cytokine production without affecting cAMP-mediated phosphodiesterase 4D (PDE4D) gene expression, phospho-cAMP response element-binding protein (p-CREB), and cAMP response element (CRE)-Luc, or PDGF-induced cyclin D1 expression. Interestingly, NHERF1 knockdown prevented ISO-induced chromatin-binding of the transcription factor CCAAT-enhancer-binding protein-β (c/EBPβ). c/EBPβ knockdown almost completely abrogated the cAMP-mediated IL-6 but not PDE4D gene expression. The differential regulation of cAMP-induced signaling and gene expression in our study indicates a role for NHERF1 in the compartmentalization of cAMP signaling in ASM.-Pera, T., Tompkins, E., Katz, M., Wang, B., Deshpande, D. A., Weinman, E. J., Penn, R. B. Specificity of NHERF1 regulation of GPCR signaling and function in human airway smooth muscle.
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Affiliation(s)
- Tonio Pera
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Center for Translational Medicine, The Jane and Leonard Korman Respiratory Institute, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Eric Tompkins
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Center for Translational Medicine, The Jane and Leonard Korman Respiratory Institute, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Michael Katz
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Center for Translational Medicine, The Jane and Leonard Korman Respiratory Institute, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Bin Wang
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Center for Translational Medicine, The Jane and Leonard Korman Respiratory Institute, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Deepak A. Deshpande
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Center for Translational Medicine, The Jane and Leonard Korman Respiratory Institute, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Edward J. Weinman
- Department of Medicine, University of Maryland, Baltimore, Maryland, USA
| | - Raymond B. Penn
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Center for Translational Medicine, The Jane and Leonard Korman Respiratory Institute, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
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17
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Seidler U, Nikolovska K. Slc26 Family of Anion Transporters in the Gastrointestinal Tract: Expression, Function, Regulation, and Role in Disease. Compr Physiol 2019; 9:839-872. [DOI: 10.1002/cphy.c180027] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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18
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Ishizuka N, Nakayama M, Watanabe M, Tajima H, Yamauchi Y, Ikari A, Hayashi H. Luminal Na + homeostasis has an important role in intestinal peptide absorption in vivo. Am J Physiol Gastrointest Liver Physiol 2018; 315:G799-G809. [PMID: 30138575 DOI: 10.1152/ajpgi.00099.2018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Intestinal cell line studies indicated luminal Na+ homeostasis is essential for proton-coupled peptide absorption, because the driving force of PepT1 activity is supported by the apical Na+/H+ exchanger NHE3. However, there is no direct evidence demonstrating the importance of in vivo luminal Na+ for peptide absorption in animal experiments. To investigate the relationship between luminal Na+ homeostasis and peptide absorption, we took advantage of claudin 15-deficient (cldn15-/-) mice, whereby Na+ homeostasis is disrupted. We quantitatively assessed the intestinal segment responsible for peptide absorption using radiolabeled nonhydrolyzable dipeptide (glycylsarcosine, Gly-Sar) and nonabsorbable fluid phase marker polyethylene glycol (PEG) 4000 in vivo. In wild-type (WT) mice, the concentration ratio of Gly-Sar to PEG 4000 decreased in the upper jejunum, suggesting the upper jejunum is responsible for peptide absorption. Gly-Sar absorption was decreased in the jejunum of cldn15-/- mice. To elucidate the mechanism underlining these impairments, a Gly-Sar-induced short-circuit ( Isc) current was measured. In WT mice, increments of Gly-Sar-induced Isc were inhibited by the luminal application of a NHE3-specific inhibitor S3226 in a dose-dependent fashion. In contrast to in vivo experiments, robust Gly-Sar-induced Isc increments were observed in the jejunal mucosa of cldn15-/- mice. Gly-Sar-induced Isc was inhibited by S3226 or a reduction of luminal Na+ concentration, which mimics low luminal Na+ concentrations in vivo . Our study demonstrates that luminal Na+ homeostasis is important for peptide absorption in native epithelia and that there is a cooperative functional relationship between PepT1 and NHE3. NEW & NOTEWORTHY Our study is the first to demonstrate that luminal Na+ homeostasis is important for proton-coupled peptide absorption in in vivo animal experiments.
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Affiliation(s)
- Noriko Ishizuka
- Laboratory of Physiology School of Food and Nutritional Sciences, University of Shizuoka, Suruga-ku, Shizuoka , Japan
| | - Michiko Nakayama
- Laboratory of Physiology School of Food and Nutritional Sciences, University of Shizuoka, Suruga-ku, Shizuoka , Japan
| | - Miki Watanabe
- Laboratory of Physiology School of Food and Nutritional Sciences, University of Shizuoka, Suruga-ku, Shizuoka , Japan
| | - Haruna Tajima
- Laboratory of Physiology School of Food and Nutritional Sciences, University of Shizuoka, Suruga-ku, Shizuoka , Japan
| | - Yuri Yamauchi
- Laboratory of Physiology School of Food and Nutritional Sciences, University of Shizuoka, Suruga-ku, Shizuoka , Japan
| | - Akira Ikari
- Laboratory of Biochemistry, Department of Biopharmaceutical Sciences, Gifu Pharmaceutical University , Gifu , Japan
| | - Hisayoshi Hayashi
- Laboratory of Physiology School of Food and Nutritional Sciences, University of Shizuoka, Suruga-ku, Shizuoka , Japan
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19
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Interrogation of the Gulf toadfish intestinal proteome response to hypersalinity exposure provides insights into osmoregulatory mechanisms and regulation of carbonate mineral precipitation. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY D-GENOMICS & PROTEOMICS 2018; 27:66-76. [DOI: 10.1016/j.cbd.2018.06.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Revised: 06/11/2018] [Accepted: 06/18/2018] [Indexed: 12/26/2022]
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20
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Lenzen H, Qian J, Manns MP, Seidler U, Jörns A. Restoration of mucosal integrity and epithelial transport function by concomitant anti-TNFα treatment in chronic DSS-induced colitis. J Mol Med (Berl) 2018; 96:831-843. [DOI: 10.1007/s00109-018-1658-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 05/27/2018] [Accepted: 06/01/2018] [Indexed: 12/25/2022]
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21
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Circadian clock component PERIOD2 regulates diurnal expression of Na +/H + exchanger regulatory factor-1 and its scaffolding function. Sci Rep 2018; 8:9072. [PMID: 29899468 PMCID: PMC5998136 DOI: 10.1038/s41598-018-27280-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 06/01/2018] [Indexed: 11/30/2022] Open
Abstract
A number of diverse cell-surface proteins are anchored to the cytoskeleton via scaffold proteins. Na+/H+ exchanger regulatory factor-1 (NHERF1), encoded by the Slc9a3r1 gene, functions as a scaffold protein, which is implicated in the regulation of membrane expression of various cell-surface proteins. Here, we demonstrate that the circadian clock component PERIOD2 (PER2) modulates transcription of the mouse Slc9a3r1 gene, generating diurnal accumulation of NHERF1 in the mouse liver. Basal expression of Slc9a3r1 was dependent on transcriptional activation by p65/p50. PER2 bound to p65 protein and prevented p65/p50-mediated transactivation of Slc9a3r1. The time-dependent interaction between PER2 and p65 underlay diurnal oscillation in the hepatic expression of Slc9a3r1/NHERF1. The results of immunoprecipitation experiments and liquid chromatography-mass spectrometry analysis of mouse liver revealed that NHERF1 time-dependently interacted with fatty acid transport protein-5 (FATP5). Temporary accumulation of NHERF1 protein stabilized plasmalemmal localization of FATP5, thereby enhancing hepatic uptake of fatty acids at certain times of the day. Our results suggest an unacknowledged role for PER2 in regulating the diurnal expression of NHERF1 in mouse liver. This machinery also contributed to diurnal changes in the ability of hepatic cells to uptake fatty acids.
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22
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García-Heredia JM, Carnero A. Dr. Jekyll and Mr. Hyde: MAP17's up-regulation, a crosspoint in cancer and inflammatory diseases. Mol Cancer 2018; 17:80. [PMID: 29650022 PMCID: PMC5896160 DOI: 10.1186/s12943-018-0828-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 03/28/2018] [Indexed: 12/14/2022] Open
Affiliation(s)
- José M García-Heredia
- Instituto de Biomedicina de Sevilla, IBIS/Hospital Universitario Virgen del Rocío/ Universidad de Sevilla/Consejo Superior de Investigaciones Científicas, Avda. Manuel Siurot s/n, 41013, Sevilla, Spain.,Department of Vegetal Biochemistry and Molecular Biology, University of Seville, Seville, Spain.,CIBER de Cáncer, Instituto de Salud Carlos III, Pabellón 11, Madrid, Spain
| | - Amancio Carnero
- Instituto de Biomedicina de Sevilla, IBIS/Hospital Universitario Virgen del Rocío/ Universidad de Sevilla/Consejo Superior de Investigaciones Científicas, Avda. Manuel Siurot s/n, 41013, Sevilla, Spain. .,CIBER de Cáncer, Instituto de Salud Carlos III, Pabellón 11, Madrid, Spain.
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23
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Avula LR, Chen T, Kovbasnjuk O, Donowitz M. Both NHERF3 and NHERF2 are necessary for multiple aspects of acute regulation of NHE3 by elevated Ca 2+, cGMP, and lysophosphatidic acid. Am J Physiol Gastrointest Liver Physiol 2018; 314:G81-G90. [PMID: 28882822 PMCID: PMC5866371 DOI: 10.1152/ajpgi.00140.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The intestinal epithelial brush border Na+/H+ exchanger NHE3 accounts for a large component of intestinal Na absorption. NHE3 is regulated during digestion by signaling complexes on its COOH terminus that include the four multi-PDZ domain-containing NHERF family proteins. All bind to NHE3 and take part in different aspects of NHE3 regulation. Because the roles of each NHERF appear to vary on the basis of the cell model or intestinal segment studied and because of our recent finding that a NHERF3-NHERF2 heterodimer appears important for NHE3 regulation in Caco-2 cells, we examined the role of NHERF3 and NHERF2 in C57BL/6 mouse jejunum using homozygous NHERF2 and NHERF3 knockout mice. NHE3 activity was determined with two-photon microscopy and the dual-emission pH-sensitive dye SNARF-4F. The jejunal apical membrane of NHERF3-null mice appeared similar to wild-type (WT) mice in surface area, microvillus number, and height, which is similar to results previously reported for jejunum of NHERF2-null mice. NHE3 basal activity was not different from WT in either NHERF2- or NHERF3-null jejunum, while d-glucose-stimulated NHE3 activity was reduced in NHERF2, but similar to WT in NHERF3 KO. LPA stimulation and UTP (elevated Ca2+) and cGMP inhibition of NHE3 were markedly reduced in both NHERF2- and NHERF3-null jejunum. Forskolin inhibited NHE3 in NHERF3-null jejunum, but the extent of inhibition was reduced compared with WT. The forskolin inhibition of NHE3 in NHERF2-null mice was too inconsistent to determine whether there was an effect and whether it was altered compared with the WT response. These results demonstrate similar requirement for NHERF2 and NHERF3 in mouse jejunal NHE3 regulation by LPA, Ca2+, and cGMP. The explanation for the similarity is not known but is consistent with involvement of a brush-border NHERF3-NHERF2 heterodimer or sequential NHERF-dependent effects in these aspects of NHE3 regulation. NEW & NOTEWORTHY NHERF2 and NHERF3 are apical membrane multi-PDZ domain-containing proteins that are involved in regulation of intestinal NHE3. This study demonstrates that NHERF2 and NHERF3 have overlapping roles in NHE3 stimulation by LPA and inhibition by elevated Ca2+ and cGMP. These results are consistent with their role being as a NHERF3-NHERF2 heterodimer or via sequential NHERF-dependent signaling steps, and they begin to clarify a role for multiple NHERF proteins in NHE3 regulation.
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Affiliation(s)
- Leela Rani Avula
- 1Department of Medicine, the Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Tiane Chen
- 1Department of Medicine, the Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Olga Kovbasnjuk
- 1Department of Medicine, the Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Mark Donowitz
- 1Department of Medicine, the Johns Hopkins School of Medicine, Baltimore, Maryland,2Department of Physiology, the Johns Hopkins University School of Medicine, Baltimore, Maryland
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Shashikanth N, Yeruva S, Ong MLDM, Odenwald MA, Pavlyuk R, Turner JR. Epithelial Organization: The Gut and Beyond. Compr Physiol 2017; 7:1497-1518. [DOI: 10.1002/cphy.c170003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Broadbent D, Ahmadzai MM, Kammala AK, Yang C, Occhiuto C, Das R, Subramanian H. Roles of NHERF Family of PDZ-Binding Proteins in Regulating GPCR Functions. Adv Immunol 2017; 136:353-385. [PMID: 28950951 DOI: 10.1016/bs.ai.2017.05.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Multicellular organisms are equipped with an array of G-protein-coupled receptors (GPCRs) that mediate cell-cell signaling allowing them to adapt to environmental cues and ultimately survive. This is mechanistically possible through complex intracellular GPCR machinery that encompasses a vast network of proteins. Within this network, there is a group called scaffolding proteins that facilitate proper localization of signaling proteins for a quick and robust GPCR response. One protein family within this scaffolding group is the PSD-95/Dlg/ZO-1 (PDZ) family which is important for GPCR localization, internalization, recycling, and downstream signaling. Although the PDZ family of proteins regulate the functions of several receptors, this chapter focuses on a subfamily within the PDZ protein family called the Na+/H+ exchanger regulatory factors (NHERFs). Here we extensively review the predominantly characterized roles of NHERFs in renal phosphate absorption, intestinal ion regulation, cancer progression, and immune cell functions. Finally, we discuss the future perspectives and possible clinical application of targeting NHERFs in several disorders.
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Affiliation(s)
| | | | | | - Canchai Yang
- Michigan State University, East Lansing, MI, United States
| | | | - Rupali Das
- Michigan State University, East Lansing, MI, United States
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Bertrand CA, Mitra S, Mishra SK, Wang X, Zhao Y, Pilewski JM, Madden DR, Frizzell RA. The CFTR trafficking mutation F508del inhibits the constitutive activity of SLC26A9. Am J Physiol Lung Cell Mol Physiol 2017; 312:L912-L925. [PMID: 28360110 PMCID: PMC5495941 DOI: 10.1152/ajplung.00178.2016] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 03/22/2017] [Accepted: 03/22/2017] [Indexed: 11/22/2022] Open
Abstract
Several members of the SLC26A family of anion transporters associate with CFTR, forming complexes in which CFTR and SLC26A functions are reciprocally regulated. These associations are thought to be facilitated by PDZ scaffolding interactions. CFTR has been shown to be positively regulated by NHERF-1, and negatively regulated by CAL in airway epithelia. However, it is unclear which PDZ-domain protein(s) interact with SLC26A9, a SLC26A family member found in airway epithelia. We have previously shown that primary, human bronchial epithelia (HBE) from non-CF donors exhibit constitutive anion secretion attributable to SLC26A9. However, constitutive anion secretion is absent in HBE from CF donors. We examined whether changes in SLC26A9 constitutive activity could be attributed to a loss of CFTR trafficking, and what role PDZ interactions played. HEK293 coexpressing SLC26A9 with the trafficking mutant F508del CFTR exhibited a significant reduction in constitutive current compared with cells coexpressing SLC26A9 and wt CFTR. We found that SLC26A9 exhibits complex glycosylation when coexpressed with F508del CFTR, but its expression at the plasma membrane is decreased. SLC26A9 interacted with both NHERF-1 and CAL, and its interaction with both significantly increased with coexpression of wt CFTR. However, coexpression with F508del CFTR only increased SLC26A9's interaction with CAL. Mutation of SLC26A9's PDZ motif decreased this association with CAL, and restored its constitutive activity. Correcting aberrant F508del CFTR trafficking in CF HBE with corrector VX-809 also restored SLC26A9 activity. We conclude that when SLC26A9 is coexpressed with F508del CFTR, its trafficking defect leads to a PDZ motif-sensitive intracellular retention of SLC26A9.
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Affiliation(s)
- Carol A Bertrand
- Departments of Pediatrics and Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania;
| | - Shalini Mitra
- Departments of Pediatrics and Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Sanjay K Mishra
- Departments of Pediatrics and Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Xiaohui Wang
- Departments of Pediatrics and Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Yu Zhao
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire
| | - Joseph M Pilewski
- Department of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; and
| | - Dean R Madden
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire
| | - Raymond A Frizzell
- Departments of Pediatrics and Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
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Camilleri M, Sellin JH, Barrett KE. Pathophysiology, Evaluation, and Management of Chronic Watery Diarrhea. Gastroenterology 2017; 152:515-532.e2. [PMID: 27773805 PMCID: PMC5285476 DOI: 10.1053/j.gastro.2016.10.014] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 09/21/2016] [Accepted: 10/11/2016] [Indexed: 02/08/2023]
Abstract
Chronic watery diarrhea poses a diagnostic and therapeutic challenge and is often a disabling condition for patients. Although acute diarrhea is likely to be caused by infection, the causes of chronic diarrhea (>4 weeks in duration) are more elusive. We review the pathophysiology, diagnosis, and treatment of chronic diarrhea. Drawing on recent insights into the molecular mechanisms of intestinal epithelial transport and barrier function, we discuss how diarrhea can result from a decrease in luminal solute absorption, an increase in secretion, or both, as well as derangements in barrier properties. We also describe the various extraepithelial factors that activate diarrheal mechanisms. Finally, clinical evaluation and tests used in the assessment of patients presenting with chronic diarrhea are reviewed, and an algorithm guiding therapeutic decisions and pharmacotherapy is presented.
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Affiliation(s)
- Michael Camilleri
- Clinical Enteric Neuroscience Translational and Epidemiological Research, Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota.
| | - Joseph H. Sellin
- Division of Gastroenterology, Department of Medicine, Baylor College of Medicine, Houston, TX
| | - Kim E. Barrett
- Division of Gastroenterology, Department of Medicine, University of California, San Diego, La Jolla, CA
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28
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van Putten JPM, Strijbis K. Transmembrane Mucins: Signaling Receptors at the Intersection of Inflammation and Cancer. J Innate Immun 2017; 9:281-299. [PMID: 28052300 DOI: 10.1159/000453594] [Citation(s) in RCA: 170] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2016] [Accepted: 11/19/2016] [Indexed: 12/18/2022] Open
Abstract
Mucosal surfaces line our body cavities and provide the interaction surface between commensal and pathogenic microbiota and the host. The barrier function of the mucosal layer is largely maintained by gel-forming mucin proteins that are secreted by goblet cells. In addition, mucosal epithelial cells express cell-bound mucins that have both barrier and signaling functions. The family of transmembrane mucins consists of diverse members that share a few characteristics. The highly glycosylated extracellular mucin domains inhibit invasion by pathogenic bacteria and can form a tight mesh structure that protects cells in harmful conditions. The intracellular tails of transmembrane mucins can be phosphorylated and connect to signaling pathways that regulate inflammation, cell-cell interactions, differentiation, and apoptosis. Transmembrane mucins play important roles in preventing infection at mucosal surfaces, but are also renowned for their contributions to the development, progression, and metastasis of adenocarcinomas. In general, transmembrane mucins seem to have evolved to monitor and repair damaged epithelia, but these functions can be highjacked by cancer cells to yield a survival advantage. This review presents an overview of the current knowledge of the functions of transmembrane mucins in inflammatory processes and carcinogenesis in order to better understand the diverse functions of these multifunctional proteins.
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Affiliation(s)
- Jos P M van Putten
- Department of Infectious Diseases and Immunology, Utrecht University, Utrecht, The Netherlands
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29
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Takei Y, Wong MKS, Pipil S, Ozaki H, Suzuki Y, Iwasaki W, Kusakabe M. Molecular mechanisms underlying active desalination and low water permeability in the esophagus of eels acclimated to seawater. Am J Physiol Regul Integr Comp Physiol 2016; 312:R231-R244. [PMID: 28003213 DOI: 10.1152/ajpregu.00465.2016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 12/19/2016] [Accepted: 12/21/2016] [Indexed: 11/22/2022]
Abstract
Marine teleosts can absorb imbibed seawater (SW) to maintain water balance, with esophageal desalination playing an essential role. NaCl absorption from luminal SW was enhanced 10-fold in the esophagus of SW-acclimated eels, and removal of Na+ or Cl- from luminal SW abolished the facilitated absorption, indicating coupled transport. Mucosal/serosal application of various blockers for Na+/Cl- transporters profoundly decreased the absorption. Among the transporter genes expressed in eel esophagus detected by RNA-seq, dimethyl amiloride-sensitive Na+/H+ exchanger (NHE3) and 4,4'-diisothiocyano-2,2'-disulfonic acid-sensitive Cl-/[Formula: see text] exchanger (AE) coupled by the scaffolding protein on the apical membrane of epithelial cells, and ouabain-sensitive Na+-K+-ATPases (NKA1α1c and NKA3α) and diphenylamine-2-carboxylic acid-sensitive Cl- channel (CLCN2) on the basolateral membrane, may be responsible for enhanced transcellular NaCl transport because of their profound upregulation after SW acclimation. Upregulated carbonic anhydrase 2a (CA2a) supplies H+ and [Formula: see text] for activation of the coupled NHE and AE. Apical hydrochlorothiazide-sensitive Na+-Cl- cotransporters and basolateral Na+-[Formula: see text] cotransporter (NBCe1) and AE1 are other possible candidates. Concerning the low water permeability that is typically seen in marine teleost esophagus, downregulated aquaporin genes (aqp1a and aqp3) and upregulated claudin gene (cldn15a) are candidates for transcellular/paracellular route. In situ hybridization showed that these upregulated transporters and tight-junction protein genes were expressed in the absorptive columnar epithelial cells of eel esophagus. These results allow us to provide a full picture of the molecular mechanism of active desalination and low water permeability that are characteristic to marine teleost esophagus and gain deeper insights into the role of gastrointestinal tracts in SW acclimation.
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Affiliation(s)
- Yoshio Takei
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, University of Tokyo, Kashiwa, Chiba, Japan;
| | - Marty K-S Wong
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, University of Tokyo, Kashiwa, Chiba, Japan
| | - Supriya Pipil
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, University of Tokyo, Kashiwa, Chiba, Japan
| | - Haruka Ozaki
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba, Japan.,Bioinformatics Research Unit, Advanced Center for Computing and Communication, RIKEN, Wako, Saitama, Japan; and
| | - Yutaka Suzuki
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba, Japan
| | - Wataru Iwasaki
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba, Japan.,Department of Biological Sciences, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Makoto Kusakabe
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, University of Tokyo, Kashiwa, Chiba, Japan
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30
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Coady MJ, El Tarazi A, Santer R, Bissonnette P, Sasseville LJ, Calado J, Lussier Y, Dumayne C, Bichet DG, Lapointe JY. MAP17 Is a Necessary Activator of Renal Na+/Glucose Cotransporter SGLT2. J Am Soc Nephrol 2016; 28:85-93. [PMID: 27288013 DOI: 10.1681/asn.2015111282] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 04/05/2016] [Indexed: 11/03/2022] Open
Abstract
The renal proximal tubule reabsorbs 90% of the filtered glucose load through the Na+-coupled glucose transporter SGLT2, and specific inhibitors of SGLT2 are now available to patients with diabetes to increase urinary glucose excretion. Using expression cloning, we identified an accessory protein, 17 kDa membrane-associated protein (MAP17), that increased SGLT2 activity in RNA-injected Xenopus oocytes by two orders of magnitude. Significant stimulation of SGLT2 activity also occurred in opossum kidney cells cotransfected with SGLT2 and MAP17. Notably, transfection with MAP17 did not change the quantity of SGLT2 protein at the cell surface in either cell type. To confirm the physiologic relevance of the MAP17-SGLT2 interaction, we studied a cohort of 60 individuals with familial renal glucosuria. One patient without any identifiable mutation in the SGLT2 coding gene (SLC5A2) displayed homozygosity for a splicing mutation (c.176+1G>A) in the MAP17 coding gene (PDZK1IP1). In the proximal tubule and in other tissues, MAP17 is known to interact with PDZK1, a scaffolding protein linked to other transporters, including Na+/H+ exchanger 3, and to signaling pathways, such as the A-kinase anchor protein 2/protein kinase A pathway. Thus, these results provide the basis for a more thorough characterization of SGLT2 which would include the possible effects of its inhibition on colocalized renal transporters.
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Affiliation(s)
- Michael J Coady
- Physics Department & Groupe d'étude des protéines membranaires
| | - Abdulah El Tarazi
- Departement of Molecular and Integrative Physiology & Groupe d'étude des protéines membranaires, and
| | - René Santer
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; and
| | - Pierre Bissonnette
- Departement of Molecular and Integrative Physiology & Groupe d'étude des protéines membranaires, and
| | | | - Joaquim Calado
- Department of Nephrology, ToxOmics, Centre for Toxicogenomics and Human Health, NOVA Medical School, New University of Lisbon, Lisbon, Portugal
| | - Yoann Lussier
- Departement of Molecular and Integrative Physiology & Groupe d'étude des protéines membranaires, and
| | - Christopher Dumayne
- Departement of Molecular and Integrative Physiology & Groupe d'étude des protéines membranaires, and
| | - Daniel G Bichet
- Departement of Molecular and Integrative Physiology & Groupe d'étude des protéines membranaires, and.,Department of Medicine, Centre de recherche de l'Hôpital du Sacré-Cœur, University of Montreal, Montreal, Quebec, Canada
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31
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Yoshida M, Zhao L, Grigoryan G, Shim H, He P, Yun CC. Deletion of Na+/H+ exchanger regulatory factor 2 represses colon cancer progress by suppression of Stat3 and CD24. Am J Physiol Gastrointest Liver Physiol 2016; 310:G586-98. [PMID: 26867566 PMCID: PMC4836134 DOI: 10.1152/ajpgi.00419.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 02/04/2016] [Indexed: 01/31/2023]
Abstract
The Na(+)/H(+) exchanger regulatory factor (NHERF) family of proteins is scaffolds that orchestrate interaction of receptors and cellular proteins. Previous studies have shown that NHERF1 functions as a tumor suppressor. The goal of this study is to determine whether the loss of NHERF2 alters colorectal cancer (CRC) progress. We found that NHERF2 expression is elevated in advanced-stage CRC. Knockdown of NHERF2 decreased cancer cell proliferation in vitro and in a mouse xenograft tumor model. In addition, deletion of NHERF2 in Apc(Min/+) mice resulted in decreased tumor growth in Apc(Min/+) mice and increased lifespan. Blocking NHERF2 interaction with a small peptide designed to bind the second PDZ domain of NHERF2 attenuated cancer cell proliferation. Although NHERF2 is known to facilitate the effects of lysophosphatidic acid receptor 2 (LPA2), transcriptome analysis of xenograft tumors revealed that NHERF2-dependent genes largely differ from LPA2-regulated genes. Activation of β-catenin and ERK1/2 was mitigated in Apc(Min/+);Nherf2(-/-) adenomas. Moreover, Stat3 phosphorylation and CD24 expression levels were suppressed in Apc(Min/+);Nherf2(-/-) adenomas. Consistently, NHERF2 knockdown attenuated Stat3 activation and CD24 expression in colon cancer cells. Interestingly, CD24 was important in the maintenance of Stat3 phosphorylation, whereas NHERF2-dependent increase in CD24 expression was blocked by inhibition of Stat3, suggesting that NHERF2 regulates Stat3 phosphorylation through a positive feedback mechanism between Stat3 and CD24. In summary, this study identifies NHERF2 as a novel oncogenic protein and a potential target for cancer treatment. NHERF2 potentiates the oncogenic effects in part by regulation of Stat3 and CD24.
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Affiliation(s)
- Michihiro Yoshida
- 1Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, Georgia; ,2Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan;
| | - Luqing Zhao
- 1Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, Georgia; ,3Division of Gastroenterology, Department of Medicine, Beijing Hospital of Traditional Chinese Medicine Affiliated to Capital Medical University, Beijing, China;
| | - Gevorg Grigoryan
- 4Department of Computer Science, Dartmouth College, Hanover, New Hampshire;
| | - Hyunsuk Shim
- 5Winship Cancer Institute, Emory University, Atlanta, Georgia; and ,6Department of Radiology and Imaging Sciences, Emory University, Atlanta, Georgia
| | - Peijian He
- 1Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, Georgia;
| | - C. Chris Yun
- 1Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, Georgia; ,5Winship Cancer Institute, Emory University, Atlanta, Georgia; and
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Magalhães D, Cabral JM, Soares-da-Silva P, Magro F. Role of epithelial ion transports in inflammatory bowel disease. Am J Physiol Gastrointest Liver Physiol 2016; 310:G460-76. [PMID: 26744474 DOI: 10.1152/ajpgi.00369.2015] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 01/02/2016] [Indexed: 02/06/2023]
Abstract
Inflammatory bowel disease (IBD) is a chronic inflammatory disorder with a complex pathogenesis. Diarrhea is a highly prevalent and often debilitating symptom of IBD patients that results, at least in part, from an intestinal hydroelectrolytic imbalance. Evidence suggests that reduced electrolyte absorption is more relevant than increased secretion to this disequilibrium. This systematic review analyses and integrates the current evidence on the roles of epithelial Na(+)-K(+)-ATPase (NKA), Na(+)/H(+) exchangers (NHEs), epithelial Na(+) channels (ENaC), and K(+) channels (KC) in IBD-associated diarrhea. NKA is the key driving force of the transepithelial ionic transport and its activity is decreased in IBD. In addition, the downregulation of apical NHE and ENaC and the upregulation of apical large-conductance KC all contribute to the IBD-associated diarrhea by lowering sodium absorption and/or increasing potassium secretion.
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Affiliation(s)
- Diogo Magalhães
- Department of Pharmacology and Therapeutics, Faculty of Medicine, Porto, Portugal; and MedInUP-Center for Drug Discovery and Innovative Medicines, University of Porto, Porto, Portugal
| | - José Miguel Cabral
- Department of Pharmacology and Therapeutics, Faculty of Medicine, Porto, Portugal; and MedInUP-Center for Drug Discovery and Innovative Medicines, University of Porto, Porto, Portugal
| | - Patrício Soares-da-Silva
- Department of Pharmacology and Therapeutics, Faculty of Medicine, Porto, Portugal; and MedInUP-Center for Drug Discovery and Innovative Medicines, University of Porto, Porto, Portugal
| | - Fernando Magro
- Department of Pharmacology and Therapeutics, Faculty of Medicine, Porto, Portugal; and MedInUP-Center for Drug Discovery and Innovative Medicines, University of Porto, Porto, Portugal
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33
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Prostacyclin receptors: Transcriptional regulation and novel signalling mechanisms. Prostaglandins Other Lipid Mediat 2015; 121:70-82. [DOI: 10.1016/j.prostaglandins.2015.04.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 03/25/2015] [Accepted: 04/18/2015] [Indexed: 12/24/2022]
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Camilleri M, Carlson P, Acosta A, Busciglio I. Colonic mucosal gene expression and genotype in irritable bowel syndrome patients with normal or elevated fecal bile acid excretion. Am J Physiol Gastrointest Liver Physiol 2015; 309:G10-20. [PMID: 25930081 PMCID: PMC4491506 DOI: 10.1152/ajpgi.00080.2015] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 04/28/2015] [Indexed: 02/08/2023]
Abstract
The mucosal gene expression in rectosigmoid mucosa (RSM) in irritable bowel syndrome with diarrhea (IBS-D) is unknown. Our objectives were, first, to study mRNA expression [by RT(2) PCR of 19 genes pertaining to tight junctions, immune activation, intestinal ion transport and bile acid (BA) homeostasis] in RSM in IBS-D patients (n = 47) and healthy controls (n = 17) and study expression of a selected protein (PDZD3) in 10 IBS-D patients and 4 healthy controls; second, to assess RSM mRNA expression according to genotype and fecal BA excretion (high ≥ 2,337 μmol/48 h); and third, to determine whether genotype or mucosal mRNA expression is associated with colonic transit or BA parameters. Fold changes were corrected for false detection rate for 19 genes studied (P < 0.00263). In RSM in IBS-D patients compared with controls, mRNA expression of GUC2AB, PDZD3, and PR2Y4 was increased, whereas CLDN1 and FN1 were decreased. One immune-related gene was upregulated (C4BP4) and one downregulated (CCL20). There was increased expression of a selected ion transport protein (PDZD3) on immunohistochemistry and Western blot in IBS-D compared with controls (P = 0.02). There were no significant differences in mucosal mRNA in 20 IBS-D patients with high compared with 27 IBS-D patients with normal BA excretion. GPBAR1 (P < 0.05) was associated with colonic transit. We concluded that mucosal ion transport mRNA (for several genes and PDZD3 protein) is upregulated and barrier protein mRNA downregulated in IBS-D compared with healthy controls, independent of genotype. There are no differences in gene expression in IBS-D with high compared with normal fecal BA excretion.
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Affiliation(s)
- Michael Camilleri
- Clinical Enteric Neuroscience Translational and Epidemiological Research (C.E.N.T.E.R.), Mayo Clinic, Rochester, Minnesota
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Camilleri M. Intestinal secretory mechanisms in irritable bowel syndrome-diarrhea. Clin Gastroenterol Hepatol 2015; 13:1051-7; quiz e61-2. [PMID: 25041862 PMCID: PMC4297594 DOI: 10.1016/j.cgh.2014.07.020] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 07/01/2014] [Accepted: 07/07/2014] [Indexed: 02/07/2023]
Abstract
Although diarrhea is the predominant bowel dysfunction in as many as one-third of patients with irritable bowel syndrome (IBS), it is unclear whether there is a specific disorder of intestinal fluid or electrolyte secretion in IBS. Diarrhea is generally considered a result of accelerated colonic transit in patients with IBS. Although a primary secretory diathesis has not been well-documented in patients with IBS with diarrhea (IBS-D), several mechanisms that could potentially contribute to intestinal secretion have been reported. Some of these mechanisms also influence motor and secretory dysfunctions that contribute to the pathophysiology of IBS-D. We review the evidence supporting secretion in IBS-D caused by peptides and amines produced by enteroendocrine cells or submucosal neurons, enterocyte secretory processes, and intraluminal factors (bile acids and short-chain fatty acids). Understanding these mechanisms and developing clinical methods for their identification could improve management of patients with IBS-D.
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Affiliation(s)
- Michael Camilleri
- Clinical Enteric Neuroscience Translational and Epidemiological Research (C.E.N.T.E.R.), Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, Minnesota.
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36
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Pelaseyed T, Bergström JH, Gustafsson JK, Ermund A, Birchenough GMH, Schütte A, van der Post S, Svensson F, Rodríguez-Piñeiro AM, Nyström EEL, Wising C, Johansson MEV, Hansson GC. The mucus and mucins of the goblet cells and enterocytes provide the first defense line of the gastrointestinal tract and interact with the immune system. Immunol Rev 2015; 260:8-20. [PMID: 24942678 DOI: 10.1111/imr.12182] [Citation(s) in RCA: 798] [Impact Index Per Article: 88.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The gastrointestinal tract is covered by mucus that has different properties in the stomach, small intestine, and colon. The large highly glycosylated gel-forming mucins MUC2 and MUC5AC are the major components of the mucus in the intestine and stomach, respectively. In the small intestine, mucus limits the number of bacteria that can reach the epithelium and the Peyer's patches. In the large intestine, the inner mucus layer separates the commensal bacteria from the host epithelium. The outer colonic mucus layer is the natural habitat for the commensal bacteria. The intestinal goblet cells secrete not only the MUC2 mucin but also a number of typical mucus components: CLCA1, FCGBP, AGR2, ZG16, and TFF3. The goblet cells have recently been shown to have a novel gate-keeping role for the presentation of oral antigens to the immune system. Goblet cells deliver small intestinal luminal material to the lamina propria dendritic cells of the tolerogenic CD103(+) type. In addition to the gel-forming mucins, the transmembrane mucins MUC3, MUC12, and MUC17 form the enterocyte glycocalyx that can reach about a micrometer out from the brush border. The MUC17 mucin can shuttle from a surface to an intracellular vesicle localization, suggesting that enterocytes might control and report epithelial microbial challenge. There is communication not only from the epithelial cells to the immune system but also in the opposite direction. One example of this is IL10 that can affect and improve the properties of the inner colonic mucus layer. The mucus and epithelial cells of the gastrointestinal tract are the primary gate keepers and controllers of bacterial interactions with the host immune system, but our understanding of this relationship is still in its infancy.
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Affiliation(s)
- Thaher Pelaseyed
- Department of Medical Biochemistry, University of Gothenburg, Gothenburg, Sweden
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Walther C, Caetano FA, Dunn HA, Ferguson SSG. PDZK1/NHERF3 differentially regulates corticotropin-releasing factor receptor 1 and serotonin 2A receptor signaling and endocytosis. Cell Signal 2015; 27:519-31. [PMID: 25562428 DOI: 10.1016/j.cellsig.2014.12.019] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 12/18/2014] [Accepted: 12/28/2014] [Indexed: 10/24/2022]
Abstract
The corticotropin-releasing factor receptor 1 (CRFR1) and serotonin 2A receptor (5-HT2AR) are linked to cellular mechanisms underlying stress anxiety and depression. Both receptors are members of the G protein-coupled receptor (GPCR) superfamily and encode class I PSD-95/DiscsLarge/Zona Occludens 1 (PDZ) binding motifs (-S/T-x-V/I/L) at the end of their carboxyl-terminal tails. We have identified PDZK1, also referred to as Na(+)/H(+) exchange regulatory cofactor 3 (NHERF3) as both a CRFR1- and 5-HT2AR-interacting protein. We have examined whether PDZK1 plays a role in regulating both CRFR1 and 5-HT2AR activity. We find that while PDZK1 interactions with CRFR1 are PDZ binding motif-dependent, PDZK1 associates with 5-HT2AR in a PDZ binding motif-independent manner and CRFR1 expression, but not 5-HT2AR expression, redistributes PDZK1 to the plasma membrane in PDZ binding motif-dependent manner. PDZK1, negatively regulates 5-HT2AR endocytosis and has no effect upon 5-HT2AR-mediated ERK1/2 phosphorylation. In contrast, PDZK1 overexpression does not affect CRFR1 endocytosis, but selectively increases CRFR1-stimulated ERK1/2 phosphorylation. Similar to what has been previously reported for PSD-95 and SAP97, PDZK1 positively influences 5-HT2AR-stimulated inositol phosphate formation, but does not contribute to the regulation of CRFR1-mediated cAMP signaling. Taken together, these results indicate that PDZK1 differentially regulates the signaling and trafficking of CRFR1 and 5-HT2AR via PDZ-dependent and -independent mechanisms, respectively.
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Affiliation(s)
- Cornelia Walther
- J. Allyn Taylor Centre for Cell Biology, Robarts Research Institute
| | | | - Henry A Dunn
- J. Allyn Taylor Centre for Cell Biology, Robarts Research Institute; Department of Physiology and Pharmacology, University of Western Ontario, 100 Perth Dr., London, Ontario, Canada, N6A5K8
| | - Stephen S G Ferguson
- J. Allyn Taylor Centre for Cell Biology, Robarts Research Institute; Department of Physiology and Pharmacology, University of Western Ontario, 100 Perth Dr., London, Ontario, Canada, N6A5K8.
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Yeruva S, Chodisetti G, Luo M, Chen M, Cinar A, Ludolph L, Lünnemann M, Goldstein J, Singh AK, Riederer B, Bachmann O, Bleich A, Gereke M, Bruder D, Hagen S, He P, Yun C, Seidler U. Evidence for a causal link between adaptor protein PDZK1 downregulation and Na⁺/H⁺ exchanger NHE3 dysfunction in human and murine colitis. Pflugers Arch 2014; 467:1795-807. [PMID: 25271043 PMCID: PMC4383727 DOI: 10.1007/s00424-014-1608-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Revised: 09/02/2014] [Accepted: 09/03/2014] [Indexed: 12/13/2022]
Abstract
A dysfunction of the Na(+)/H(+) exchanger isoform 3 (NHE3) significantly contributes to the reduced salt absorptive capacity of the inflamed intestine. We previously reported a strong decrease in the NHERF family member PDZK1 (NHERF3), which binds to NHE3 and regulates its function in a mouse model of colitis. The present study investigates whether a causal relationship exists between the decreased PDZK1 expression and the NHE3 dysfunction in human and murine intestinal inflammation. Biopsies from the colon of patients with ulcerative colitis, murine inflamed ileal and colonic mucosa, NHE3-transfected Caco-2BBe colonic cells with short hairpin RNA (shRNA) knockdown of PDZK1, and Pdzk1-gene-deleted mice were studied. PDZK1 mRNA and protein expression was strongly decreased in inflamed human and murine intestinal tissue as compared to inactive disease or control tissue, whereas that of NHE3 or NHERF1 was not. Inflamed human and murine intestinal tissues displayed correct brush border localization of NHE3 but reduced acid-activated NHE3 transport activity. A similar NHE3 transport defect was observed when PDZK1 protein content was decreased by shRNA knockdown in Caco-2BBe cells or when enterocyte PDZK1 protein content was decreased to similar levels as found in inflamed mucosa by heterozygote breeding of Pdzk1-gene-deleted and WT mice. We conclude that a decrease in PDZK1 expression, whether induced by inflammation, shRNA-mediated knockdown, or heterozygous breeding, is associated with a decreased NHE3 transport rate in human and murine enterocytes. We therefore hypothesize that inflammation-induced loss of PDZK1 expression may contribute to the NHE3 dysfunction observed in the inflamed intestine.
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Affiliation(s)
- Sunil Yeruva
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Carl-Neuberg-Straße 1, 30625, Hannover, Germany
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Sultan A, Luo M, Yu Q, Riederer B, Xia W, Chen M, Lissner S, Gessner JE, Donowitz M, Yun CC, deJonge H, Lamprecht G, Seidler U. Differential association of the Na+/H+ Exchanger Regulatory Factor (NHERF) family of adaptor proteins with the raft- and the non-raft brush border membrane fractions of NHE3. Cell Physiol Biochem 2014; 32:1386-402. [PMID: 24297041 DOI: 10.1159/000356577] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/24/2013] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND/AIMS Trafficking, brush border membrane (BBM) retention, and signal-specific regulation of the Na+/H+ exchanger NHE3 is regulated by the Na+/H+ Exchanger Regulatory Factor (NHERF) family of PDZ-adaptor proteins, which enable the formation of multiprotein complexes. It is unclear, however, what determines signal specificity of these NHERFs. Thus, we studied the association of NHE3, NHERF1 (EBP50), NHERF2 (E3KARP), and NHERF3 (PDZK1) with lipid rafts in murine small intestinal BBM. METHODS Detergent resistant membranes ("lipid rafts") were isolated by floatation of Triton X-incubated small intestinal BBM from a variety of knockout mouse strains in an Optiprep step gradient. Acid-activated NHE3 activity was measured fluorometrically in BCECF-loaded microdissected villi, or by assessment of CO2/HCO3(-) mediated increase in fluid absorption in perfused jejunal loops of anethetized mice. RESULTS NHE3 was found to partially associate with lipid rafts in the native BBM, and NHE3 raft association had an impact on NHE3 transport activity and regulation in vivo. NHERF1, 2 and 3 were differentially distributed to rafts and non-rafts, with NHERF2 being most raft-associated and NHERF3 entirely non-raft associated. NHERF2 expression enhanced the localization of NHE3 to membrane rafts. The use of acid sphingomyelinase-deficient mice, which have altered membrane lipid as well as lipid raft composition, allowed us to test the validity of the lipid raft concept in vivo. CONCLUSIONS The differential association of the NHERFs with the raft-associated and the non-raft fraction of NHE3 in the brush border membrane is one component of the differential and signal-specific NHE3 regulation by the different NHERFs.
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Lee HJ, Kwon MH, Lee S, Hall RA, Yun CC, Choi I. Systematic family-wide analysis of sodium bicarbonate cotransporter NBCn1/SLC4A7 interactions with PDZ scaffold proteins. Physiol Rep 2014; 2:2/5/e12016. [PMID: 24844638 PMCID: PMC4098744 DOI: 10.14814/phy2.12016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
NBCn1 (SLC4A7) plays a role in transepithelial HCO3 (-) movement and intracellular pH maintenance in many tissues. In this study, we searched PDZ proteins capable of binding to NBCn1. We screened a protein array membrane, on which 96 different class I PDZ protein peptides were blotted, with the C-terminal domain of NBCn1 fused to GST. Thirteen proteins were identified in these screens: MAGI-3, NHERF-1, NHERF-2, PSD-95, chapsyn-110, ERBIN, MALS-1, densin-180, syntrophins α1, β2, γ2, MUPP1, and PDZK1. After determining these binding partners, we analyzed the database of known and predicted protein interactions to obtain an NBCn1 interaction network. The network shows NBCn1 being physically and functionally associated with a variety of membrane and cytosolic proteins via the binding partners. We then focused on syntrophin γ2 to examine the molecular and functional interaction between NBCn1 and one of the identified binding partners in the Xenopus oocyte expression system. GST/NBCn1 pulled down syntrophin γ2 and conversely GST/syntrophin γ2 pulled down NBCn1. Moreover, syntrophin γ2 increased intracellular pH recovery, from acidification, mediated by NBCn1's Na/HCO3 cotransport. Syntrophin γ2 also increased an ionic conductance produced by NBCn1 channel-like activity. Thus, syntrophin γ2 regulates NBCn1 activity. In conclusion, this study demonstrates that NBCn1 binds to many PDZ proteins, which in turn may allow the transporter to associate with other physiologically important proteins.
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Affiliation(s)
- Hye Jeong Lee
- Department of Pediatrics, Division of Hematology and Oncology, Vanderbilt University, Nashville, Tennessee, USA
| | - Min Hyung Kwon
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Soojung Lee
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Randy A Hall
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - C Chris Yun
- Department of Medicine, Division of Digestive Disease, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Inyeong Choi
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia, USA
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The role of pancreatic ductal secretion in protection against acute pancreatitis in mice*. Crit Care Med 2014; 42:e177-88. [PMID: 24368347 DOI: 10.1097/ccm.0000000000000101] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
OBJECTIVES A common potentially fatal disease of the pancreas is acute pancreatitis, for which there is no treatment. Most studies of this disorder focus on the damage to acinar cells since they are assumed to be the primary target of multiple stressors affecting the pancreas. However, increasing evidence suggests that the ducts may also have a crucial role in induction of the disease. To test this hypothesis, we sought to determine the specific role of the duct in the induction of acute pancreatitis using well-established disease models and mice with deletion of the Na/H exchanger regulatory factor-1 that have selectively impaired ductal function. DESIGN Randomized animal study. SETTING Animal research laboratory. SUBJECTS Wild-type and Na/H exchanger regulatory factor-1 knockout mice. INTERVENTIONS Acute necrotizing pancreatitis was induced by i.p. administration of cerulein or by intraductal administration of sodium taurocholate. The pancreatic expression of Na/H exchanger regulatory factor-1 and cystic fibrosis transmembrane conductance regulator (a key player in the control of ductal secretion) was analyzed by immunohistochemistry. In vivo pancreatic ductal secretion was studied in anesthetized mice. Functions of pancreatic acinar and ductal cells as well as inflammatory cells were analyzed in vitro. MEASUREMENTS AND MAIN RESULTS Deletion of Na/H exchanger regulatory factor-1 resulted in gross mislocalization of cystic fibrosis transmembrane conductance regulator, causing marked reduction in pancreatic ductal fluid and bicarbonate secretion. Importantly, deletion of Na/H exchanger regulatory factor-1 had no deleterious effect on functions of acinar and inflammatory cells. Deletion of Na/H exchanger regulatory factor-1, which specifically impaired ductal function, increased the severity of acute pancreatitis in the two mouse models tested. CONCLUSIONS Our findings provide the first direct evidence for the crucial role of ductal secretion in protecting the pancreas from acute pancreatitis and strongly suggest that improved ductal function should be an important modality in prevention and treatment of the disease.
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Jung ES, Park J, Gee HY, Jung J, Noh SH, Lee JS, Richter W, Namkung W, Lee MG. Shank2 mutant mice display a hypersecretory response to cholera toxin. J Physiol 2014; 592:1809-21. [PMID: 24445315 DOI: 10.1113/jphysiol.2013.268631] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Shank2 is a PDZ (PSD-95/discs large/ZO-1)-based adaptor that has been suggested to regulate membrane transporting proteins in the brain and epithelial tissues. Here, we report that Shank2 mutant (Shank2(-/-)) mice exhibit aberrant fluid and ion transport in the intestine. Molecular characterization using epithelial tissues from Shank2(+/+) and Shank2(-/-) mice revealed that a long spliceoform of Shank2 (Shank2E) is predominantly expressed in the pancreatic, renal and intestinal epithelia. In functional assays, deletion of Shank2 increased the cystic fibrosis transmembrane conductance regulator (CFTR)-dependent short-circuit currents by 84% (P < 0.05) and 101% (P < 0.05) in the mouse colon and rectum, respectively. Disruption of the CFTR-Shank2-phosphodiesterase 4D protein complex appeared to be mostly responsible for the changes in CFTR activities. Notably, Shank2 deletion profoundly increased cholera toxin-induced fluid accumulation in the mouse intestine (∼90%, P < 0.01). Analyses with chemical inhibitors confirmed that the hyperactivation of CFTR channel function is responsible for the increased response to cholera toxin. These results suggest that Shank2 is a key molecule that participates in epithelial homeostasis, in particular to prevent overt secretory responses caused by epithelial pathogens.
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Affiliation(s)
- Eun Suk Jung
- Department of Pharmacology, Yonsei University College of Medicine, 134 Sinchon-Dong, Seoul 120-752, Korea.
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Lissner S, Hsieh CJ, Nold L, Bannert K, Bodammer P, Sultan A, Seidler U, Graeve L, Lamprecht G. The PDZ-interaction of the intestinal anion exchanger downregulated in adenoma (DRA; SLC26A3) facilitates its movement into Rab11a-positive recycling endosomes. Am J Physiol Gastrointest Liver Physiol 2013; 304:G980-90. [PMID: 23578788 DOI: 10.1152/ajpgi.00132.2012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Electroneutral NaCl absorption in the ileum and colon is mediated by downregulated in adenoma (DRA) (Cl⁻/HCO₃⁻ exchanger; SLC26A3) and Na⁺/H⁺ exchanger 3 (NHE3, SLC9A3). Surface expression of transport proteins undergoes basal and regulated recycling by endo- and exocytosis. Expression and activity of DRA in the plasma membrane depend on intact lipid rafts, phosphatidylinositol 3-kinase (PI3-kinase), and the PDZ interaction of DRA. However, it is unknown how the PDZ interaction of DRA affects its trafficking to the cell surface. Therefore, the (re)cycling pathway of DRA was investigated in HEK cells stably expressing enhanced green fluorescent protein (EGFP)-DRA or EGFP-DRA-ETKFminus (a mutant lacking the PDZ interaction motif). Early, late, and recycling endosomes were immunoisolated by precipitating stably transfected mCherry-hemagglutinin (HA)-Rab5a, -7a, or -11a. EGFP-DRA and EGFP-DRA-ETKFminus were equally present in early endosomes. In recycling endosomes, wild-type DRA was preferentially present, whereas, in late endosomes, DRA-ETKF-minus dominated. Correspondingly, EGFP-DRA colocalized with mCherry-HA-Rab11a in recycling endosomes, whereas EGFP-DRA-ETKFminus colocalized with mCherry-HA-Rab7a in late endosomes. Functionally, this different distribution was reflected by a shorter half-life of the mutant DRA. Transient expression of dominant-negative Rab11a(S25N) inhibited the activity (-17%, P < 0.05) and the cell surface expression of DRA (-30%, P < 0.05). Transient transfection of Rab4a or its dominant-negative mutant Rab4a(S22N) was without effect and thus excluded participation of the rapid recycling pathway. Taken together, the PDZ interaction of DRA facilitates its movement into Rab11a-positive recycling endosomes, from where it is inserted in the plasma membrane. A scenario emerges where specific PDZ adaptor proteins are present along several compartments of the endocytosis-recycling pathway.
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Affiliation(s)
- S Lissner
- 1st Medical Department, University of Tübingen, Tübingen, Germany
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Ren A, Zhang W, Yarlagadda S, Sinha C, Arora K, Moon CS, Naren AP. MAST205 competes with cystic fibrosis transmembrane conductance regulator (CFTR)-associated ligand for binding to CFTR to regulate CFTR-mediated fluid transport. J Biol Chem 2013; 288:12325-34. [PMID: 23504457 DOI: 10.1074/jbc.m112.432724] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The PDZ (postsynaptic density-95/discs large/zona occludens-1) domain-based interactions play important roles in regulating the expression and function of the cystic fibrosis transmembrane conductance regulator (CFTR). Several PDZ domain-containing proteins (PDZ proteins for short) have been identified as directly or indirectly interacting with the C terminus of CFTR. To better understand the regulation of CFTR processing, we conducted a genetic screen and identified MAST205 (a microtubule-associated serine/threonine kinase with a molecular mass of 205 kDa) as a new CFTR regulator. We found that overexpression of MAST205 increased the expression of CFTR and augmented CFTR-mediated fluid transport in a dose-dependent manner. Conversely, knockdown of MAST205 inhibited CFTR function. The PDZ motif of CFTR is required for the regulatory role of MAST205 in CFTR expression and function. We further demonstrated that MAST205 and the CFTR-associated ligand competed for binding to CFTR, which facilitated the processing of CFTR and consequently up-regulated the expression and function of CFTR at the plasma membrane. More importantly, we found that MAST205 could facilitate the processing of F508del-CFTR mutant and augment its quantity and channel function at the plasma membrane. Taken together, our data suggest that MAST205 plays an important role in regulating CFTR expression and function. Our findings have important clinical implications for treating CFTR-associated diseases such as cystic fibrosis and secretory diarrheas.
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Affiliation(s)
- Aixia Ren
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
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Birrane G, Mulvaney EP, Pal R, Kinsella BT, Kocher O. Molecular analysis of the prostacyclin receptor's interaction with the PDZ1 domain of its adaptor protein PDZK1. PLoS One 2013; 8:e53819. [PMID: 23457445 PMCID: PMC3566133 DOI: 10.1371/journal.pone.0053819] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Accepted: 12/03/2012] [Indexed: 01/07/2023] Open
Abstract
The prostanoid prostacyclin, or prostaglandin I2, plays an essential role in many aspects of cardiovascular disease. The actions of prostacyclin are mainly mediated through its activation of the prostacyclin receptor or, in short, the IP. In recent studies, the cytoplasmic carboxy-terminal domain of the IP was shown to bind several PDZ domains of the multi-PDZ adaptor PDZK1. The interaction between the two proteins was found to enhance cell surface expression of the IP and to be functionally important in promoting prostacyclin-induced endothelial cell migration and angiogenesis. To investigate the interaction of the IP with the first PDZ domain (PDZ1) of PDZK1, we generated a nine residue peptide (KK(411)IAACSLC(417)) containing the seven carboxy-terminal amino acids of the IP and measured its binding affinity to a recombinant protein corresponding to PDZ1 by isothermal titration calorimetry. We determined that the IP interacts with PDZ1 with a binding affinity of 8.2 µM. Using the same technique, we also determined that the farnesylated form of carboxy-terminus of the IP does not bind to PDZ1. To understand the molecular basis of these findings, we solved the high resolution crystal structure of PDZ1 bound to a 7-residue peptide derived from the carboxy-terminus of the non-farnesylated form of IP ((411)IAACSLC(417)). Analysis of the structure demonstrates a critical role for the three carboxy-terminal amino acids in establishing a strong interaction with PDZ1 and explains the inability of the farnesylated form of IP to interact with the PDZ1 domain of PDZK1 at least in vitro.
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Affiliation(s)
- Gabriel Birrane
- Division of Experimental Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Eamon P. Mulvaney
- School of Biomolecular and Biomedical Sciences, Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin, Ireland
| | - Rinku Pal
- Department of Pathology and Center for Vascular Biology Research, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
| | - B. Therese Kinsella
- School of Biomolecular and Biomedical Sciences, Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin, Ireland
| | - Olivier Kocher
- Department of Pathology and Center for Vascular Biology Research, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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Kim NH, Cheong KA, Lee TR, Lee AY. PDZK1 Upregulation in Estrogen-Related Hyperpigmentation in Melasma. J Invest Dermatol 2012; 132:2622-31. [DOI: 10.1038/jid.2012.175] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Interaction of the human prostacyclin receptor and the NHERF4 family member intestinal and kidney enriched PDZ protein (IKEPP). BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:1998-2012. [DOI: 10.1016/j.bbamcr.2012.07.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Revised: 07/27/2012] [Accepted: 07/30/2012] [Indexed: 11/24/2022]
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Giral H, Cranston D, Lanzano L, Caldas Y, Sutherland E, Rachelson J, Dobrinskikh E, Weinman EJ, Doctor RB, Gratton E, Levi M. NHE3 regulatory factor 1 (NHERF1) modulates intestinal sodium-dependent phosphate transporter (NaPi-2b) expression in apical microvilli. J Biol Chem 2012; 287:35047-35056. [PMID: 22904329 DOI: 10.1074/jbc.m112.392415] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
P(i) uptake in the small intestine occurs predominantly through the NaPi-2b (SLC34a2) co-transporter. NaPi-2b is regulated by changes in dietary P(i) but the mechanisms underlying this regulation are largely undetermined. Sequence analyses show NaPi-2b has a PDZ binding motif at its C terminus. Immunofluorescence imaging shows NaPi-2b and two PDZ domain containing proteins, NHERF1 and PDZK1, are expressed in the apical microvillar domain of rat small intestine enterocytes. Co-immunoprecipitation studies in rat enterocytes show that NHERF1 associates with NaPi-2b but not PDZK1. In HEK co-expression studies, GFP-NaPi-2b co-precipitates with FLAG-NHERF1. This interaction is markedly diminished when the C-terminal four amino acids are truncated from NaPi-2b. FLIM-FRET analyses using tagged proteins in CACO-2(BBE) cells show a distinct phasor shift between NaPi-2b and NHERF1 but not between NaPi-2b and the PDZK1 pair. This shift demonstrates that NaPi-2b and NHERF1 reside within 10 nm of each other. NHERF1(-/-) mice, but not PDZK1(-/-) mice, had a diminished adaptation of NaPi-2b expression in response to a low P(i) diet. Together these studies demonstrate that NHERF1 associates with NaPi-2b in enterocytes and regulates NaPi-2b adaptation.
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Affiliation(s)
- Hector Giral
- Department of Medicine, University of Colorado Denver, Aurora, Colorado and the Veterans Affairs Eastern Colorado Health Care System, Denver, Colorado 80045
| | - DeeAnn Cranston
- Department of Medicine, University of Colorado Denver, Aurora, Colorado and the Veterans Affairs Eastern Colorado Health Care System, Denver, Colorado 80045
| | - Luca Lanzano
- Department of Biomedical Engineering, Laboratory for Fluorescence Dynamics, University of California, Irvine, California 92697
| | - Yupanqui Caldas
- Department of Medicine, University of Colorado Denver, Aurora, Colorado and the Veterans Affairs Eastern Colorado Health Care System, Denver, Colorado 80045
| | - Eileen Sutherland
- Department of Medicine, University of Colorado Denver, Aurora, Colorado and the Veterans Affairs Eastern Colorado Health Care System, Denver, Colorado 80045
| | - Joanna Rachelson
- Department of Medicine, University of Colorado Denver, Aurora, Colorado and the Veterans Affairs Eastern Colorado Health Care System, Denver, Colorado 80045
| | - Evgenia Dobrinskikh
- Department of Medicine, University of Colorado Denver, Aurora, Colorado and the Veterans Affairs Eastern Colorado Health Care System, Denver, Colorado 80045
| | - Edward J Weinman
- Department of Medicine and Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - R Brian Doctor
- Department of Medicine, University of Colorado Denver, Aurora, Colorado and the Veterans Affairs Eastern Colorado Health Care System, Denver, Colorado 80045
| | - Enrico Gratton
- Department of Biomedical Engineering, Laboratory for Fluorescence Dynamics, University of California, Irvine, California 92697
| | - Moshe Levi
- Department of Medicine, University of Colorado Denver, Aurora, Colorado and the Veterans Affairs Eastern Colorado Health Care System, Denver, Colorado 80045.
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Lenzen H, Lünnemann M, Bleich A, Manns MP, Seidler U, Jörns A. Downregulation of the NHE3-binding PDZ-adaptor protein PDZK1 expression during cytokine-induced inflammation in interleukin-10-deficient mice. PLoS One 2012; 7:e40657. [PMID: 22848392 PMCID: PMC3407152 DOI: 10.1371/journal.pone.0040657] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Accepted: 06/11/2012] [Indexed: 12/21/2022] Open
Abstract
Background Impaired salt and water absorption is an important feature in the pathogenesis of diarrhea in inflammatory bowel disease (IBD). We analyzed the expression of proinflammatory cytokines in the infiltrating immune cells and the function and expression of the Na+/H+ exchanger isoform 3 (NHE3) and its regulatory PDZ-adaptor proteins NHERF1, NHERF2, and PDZK1 in the colon of interleukin-10–deficient (IL-10−/−) mice. Methodology/Principal Findings Gene and protein expression were analyzed by real-time reverse transcription polymerase chain reaction (qRT-PCR), in situ RT-PCR, and immunohistochemistry. NHE3 activity was measured fluorometrically in apical enterocytes within isolated colonic crypts. Mice developed chronic colitis characterized by a typical immune cell infiltration composed of T-lymphocytes and macrophages, with high levels of gene and protein expression of the proinflammatory cytokines interleukin-1β and tumor necrosis factor-α. In parallel, inducible nitric oxide synthase expression was increased while procaspase 3 expression was unaffected. Interferon-γ expression remained low. Although acid-activated NHE3 activity was significantly decreased, the inflammatory process did not affect its gene and protein expression or its abundance and localization in the apical membrane. However, expression of the PDZ-adaptor proteins NHERF2 and PDZK1 was downregulated. NHERF1 expression was unchanged. In a comparative analysis we observed the PDZK1 downregulation also in the DSS (dextran sulphate sodium) model of colitis. Conclusions/Significance The impairment of the absorptive function of the inflamed colon in the IL-10−/−mouse, in spite of unaltered NHE3 expression and localization, is accompanied by the downregulation of the NHE3-regulatory PDZ adaptors NHERF2 and PDZK1. We propose that the downregulation of PDZ-adaptor proteins may be an important factor leading to NHE3 dysfunction and diarrhea in the course of the cytokine-mediated inflammatory process in these animal models of IBD.
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Affiliation(s)
- Henrike Lenzen
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany.
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Yoo BK, Yanda MK, No YR, Yun CC. Human intestinal epithelial cell line SK-CO15 is a new model system to study Na(+)/H(+) exchanger 3. Am J Physiol Gastrointest Liver Physiol 2012; 303:G180-8. [PMID: 22556145 PMCID: PMC3404572 DOI: 10.1152/ajpgi.00069.2012] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The Caco-2 cell line represents absorptive polarized intestinal epithelial cells that express multiple forms of Na(+)/H(+) exchanger (NHE) in their plasma membranes. Caco-2 cells express the major apical NHE isoform NHE3, but low NHE3 expression together with inefficient transfection often hamper intended studies. In this study, we examined whether SK-CO15 cells could be used to study NHE3 regulation. SK-CO15 cells grown on Transwell inserts developed polarized epithelial cells with microvilli. The transfection efficiency of SK-CO15 cells was markedly higher compared with Caco-2 cells, an advantage in gene transfer and knockout. SK-CO15 cells expressed NHE1, NHE2, and NHE3. NHE3 expression was significantly greater in these cells than Caco-2, and NHE3 comprised more than half of total NHE activity. Apical expression of NHE3 in SK-CO15 cells was confirmed by confocal immunofluorescence and surface biotinylation. NHE regulatory factors NHERF1 and NHERF2, which are important for regulation of NHE3 activity, were expressed in these cells. Stimulatory response of NHE3 in SK-CO15 cells was assessed by dexamethasone and lysophosphatidic acid (LPA). Treatment with dexamethasone for 24-48 h increased NHE3 expression and activity. Similarly to Caco-2 cells, SK-CO15 cells lacked the expression of the LPA receptor LPA(5,) but exogenous expression of LPA(5) resulted in acute stimulation of NHE3. Forskolin acutely inhibited NHE3 activity in SK-CO15 cells, further attesting the validity of these cells. We conclude that SK-CO15 cells with the amenity for transfection and high endogenous NHE3 expression are a new and better cell model for NHE3 regulatory investigation than widely used Caco-2 cells.
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Affiliation(s)
- Byong Kwon Yoo
- Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, Georgia
| | - Murali Krishna Yanda
- Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, Georgia
| | - Yi Ran No
- Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, Georgia
| | - C. Chris Yun
- Division of Digestive Diseases, Department of Medicine, Emory University, Atlanta, Georgia
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