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Ryuzaki M, Miyashita K, Sato M, Inoue H, Fujii K, Hagiwara A, Uto A, Endo S, Oshida T, Kinouchi K, Itoh H. Activation of the intestinal tissue renin-angiotensin system by transient sodium loading in salt-sensitive rats. J Hypertens 2022; 40:33-45. [PMID: 34285148 PMCID: PMC8654260 DOI: 10.1097/hjh.0000000000002974] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 06/14/2021] [Accepted: 07/04/2021] [Indexed: 11/25/2022]
Abstract
BACKGROUND The renal tissue renin-angiotensin system is known to be activated by salt loading in salt-sensitive rats; however, the response in other organs remains unclear. METHOD Spontaneously hypertensive rats were subjected to normal tap water or transient high-salt-concentration water from 6 to 14 weeks of age and were thereafter given normal tap water. From 18 to 20 weeks of age, rats given water with a high salt concentration were treated with an angiotensin II type 1 receptor blocker, valsartan. RESULTS Sustained blood pressure elevation by transient salt loading coincided with a persistent decrease in the fecal sodium content and sustained excess of the circulating volume in spontaneously hypertensive rats. Administration of valsartan sustainably reduced the blood pressure and normalized the fecal sodium levels. Notably, transient salt loading persistently induced the intestinal tissue renin-angiotensin system and enhanced sodium transporter expression exclusively in the small intestine of salt-sensitive rats, suggesting the potential connection of intestinal sodium absorption to salt sensitivity. CONCLUSION These results reveal the previously unappreciated contribution of the intestinal tissue renin-angiotensin system to sodium homeostasis and blood pressure regulation in the pathophysiology of salt-sensitive hypertension.
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Affiliation(s)
- Masaki Ryuzaki
- Division of Endocrinology, Metabolism, and Nephrology, Department of Internal Medicine, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
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Linz B, Saljic A, Hohl M, Gawałko M, Jespersen T, Sanders P, Böhm M, Linz D. Inhibition of sodium-proton-exchanger subtype 3-mediated sodium absorption in the gut: A new antihypertensive concept. IJC HEART & VASCULATURE 2020; 29:100591. [PMID: 32760780 PMCID: PMC7390783 DOI: 10.1016/j.ijcha.2020.100591] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 06/24/2020] [Accepted: 07/07/2020] [Indexed: 12/22/2022]
Abstract
Arterial hypertension is one of the main contributors to cardiovascular diseases, including stroke, heart failure, and coronary heart disease. Salt plays a major role in the regulation of blood pressure and is one of the most critical factors for hypertension and stroke. At the individual level, effective salt reduction is difficult to achieve and available methods for managing sodium balance are lacking for many patients. As part of the ingested food, salt is absorbed in the gastrointestinal tract by the sodium proton exchanger subtype 3 (NHE3 also known as Slc9a3), influencing extracellular fluid volume and blood pressure. In this review, we discuss the beneficial effects of pharmacological inhibition of NHE3-mediated sodium absorption in the gut and focus on the effect on blood pressure and end-organ damage.
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Affiliation(s)
- Benedikt Linz
- Faculty of Health and Medical Sciences, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Arnela Saljic
- Faculty of Health and Medical Sciences, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mathias Hohl
- Kardiologie, Angiologie und Internistische Intensivmedizin, Universitätsklinikum des Saarlandes
| | - Monika Gawałko
- 1st Department of Cardiology, Medical University of Warsaw, Warsaw, Poland
- Department of Cardiology, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Thomas Jespersen
- Faculty of Health and Medical Sciences, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Prashanthan Sanders
- Centre for Heart Rhythm Disorders, Royal Adelaide Hospital, University of Adelaide, Adelaide, Australia
| | - Michael Böhm
- Kardiologie, Angiologie und Internistische Intensivmedizin, Universitätsklinikum des Saarlandes
| | - Dominik Linz
- Department of Cardiology, Maastricht University Medical Centre, Maastricht, the Netherlands
- Centre for Heart Rhythm Disorders, Royal Adelaide Hospital, University of Adelaide, Adelaide, Australia
- University Maastricht, Cardiovascular Research Institute Maastricht (CARIM), the Netherlands
- Corresponding author at: Maastricht UMC+, Maastricht Heart+Vascular Center, 6202 AZ Maastricht, the Netherlands.
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Kumar A, Priyamvada S, Soni V, Anbazhagan AN, Gujral T, Gill RK, Alrefai WA, Dudeja PK, Saksena S. Angiotensin II inhibits P-glycoprotein in intestinal epithelial cells. Acta Physiol (Oxf) 2020; 228:e13332. [PMID: 31177627 PMCID: PMC6899205 DOI: 10.1111/apha.13332] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Revised: 05/24/2019] [Accepted: 06/04/2019] [Indexed: 01/15/2023]
Abstract
AIM P-glycoprotein (Pgp/MDR1) plays a major role in intestinal homeostasis. Decrease in Pgp function and expression has been implicated in the pathogenesis of IBD. However, inhibitory mechanisms involved in the decrease of Pgp in inflammation are not fully understood. Angiotensin II (Ang II), a peptide hormone predominantly expressed in the epithelial cells of the crypt-villus junction of the intestine, has been shown to exert pro-inflammatory effects in the gut. It is increased in IBD patients and animals with experimental colitis. Whether Ang II directly influences Pgp is not known. METHODS Pgp activity was measured as verapamil-sensitive 3 H-digoxin flux. Pgp surface expression and exocytosis were measured by cell surface biotinylation studies. Signalling pathways were elucidated by Western blot analysis and pharmacological approaches. RESULTS Ang II (10 nM) significantly inhibited Pgp activity at 60 minutes. Ang II-mediated effects on Pgp function were receptor-mediated as the Ang II receptor 1 (ATR1) antagonist, losartan, blocked Pgp inhibition. Ang II effects on Pgp activity appeared to be mediated via PI3 kinase, p38 MAPK and Akt signalling. Ang II-mediated inhibition of Pgp activity was associated with a decrease in the surface membrane expression of Pgp protein via decreased exocytosis and was found to be dependent on the Akt pathway. Short-term treatment of Ang II (2 mg/kg b.wt., 2 hours) to mice also decreased the membrane expression of Pgp protein levels in ileum and colon. CONCLUSION Our findings provide novel insights into the role of Ang II and ATR1 in decreasing Pgp expression in intestinal inflammation.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics
- ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism
- Angiotensin II/administration & dosage
- Angiotensin II/pharmacology
- Animals
- Caco-2 Cells
- Dose-Response Relationship, Drug
- Epithelial Cells/drug effects
- Epithelial Cells/metabolism
- Gene Expression Regulation/drug effects
- Humans
- Intestinal Mucosa/cytology
- Mice
- Phosphatidylinositol 3-Kinases/genetics
- Phosphatidylinositol 3-Kinases/metabolism
- Proto-Oncogene Proteins c-akt/genetics
- Proto-Oncogene Proteins c-akt/metabolism
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
- Receptor, Angiotensin, Type 2/genetics
- Receptor, Angiotensin, Type 2/metabolism
- p38 Mitogen-Activated Protein Kinases/genetics
- p38 Mitogen-Activated Protein Kinases/metabolism
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Affiliation(s)
- Anoop Kumar
- Division of Gastroenterology & Hepatology, Dept. of Medicine, University of Illinois at Chicago
| | - Shubha Priyamvada
- Division of Gastroenterology & Hepatology, Dept. of Medicine, University of Illinois at Chicago
| | - Vikas Soni
- Division of Gastroenterology & Hepatology, Dept. of Medicine, University of Illinois at Chicago
| | - Arivarasu N. Anbazhagan
- Division of Gastroenterology & Hepatology, Dept. of Medicine, University of Illinois at Chicago
| | - Tarunmeet Gujral
- Division of Gastroenterology & Hepatology, Dept. of Medicine, University of Illinois at Chicago
| | - Ravinder K Gill
- Division of Gastroenterology & Hepatology, Dept. of Medicine, University of Illinois at Chicago
| | - Waddah A. Alrefai
- Division of Gastroenterology & Hepatology, Dept. of Medicine, University of Illinois at Chicago
- Jesse Brown VA Medical Center, Chicago, IL 60612
| | - Pradeep K. Dudeja
- Division of Gastroenterology & Hepatology, Dept. of Medicine, University of Illinois at Chicago
- Jesse Brown VA Medical Center, Chicago, IL 60612
| | - Seema Saksena
- Division of Gastroenterology & Hepatology, Dept. of Medicine, University of Illinois at Chicago
- Jesse Brown VA Medical Center, Chicago, IL 60612
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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: 110] [Impact Index Per Article: 22.0] [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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Pringle KG, Wang Y, Lumbers ER. The synthesis, secretion and uptake of prorenin in human amnion. Physiol Rep 2015; 3:3/4/e12313. [PMID: 25902786 PMCID: PMC4425950 DOI: 10.14814/phy2.12313] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Very high concentrations of prorenin protein occur in human amniotic fluid and amnion. The source of amniotic fluid prorenin is likely the decidua, as it has the highest levels of prorenin mRNA (REN). Conversely, REN mRNA levels in amnion and chorion are very low. This study aimed to investigate whether decidual prorenin could cross the amnion and accumulate in amniotic fluid. Late gestation amnion was incubated for 24 h in the presence or absence of recombinant human (rh)prorenin. REN mRNA abundance was determined by qPCR and prorenin protein levels in the supernatant and tissue were measured by an ELISA. Prior to incubation only 3/11 amnion samples had REN mRNA but measurable levels of prorenin protein were found (1.4 ng/mg total protein). After 24 h incubation, REN mRNA was found in all explants and levels were significantly increased (P = 0.03) but prorenin protein levels in amnion were unchanged. Prorenin protein levels in the supernatant were, however, increased (P = 0.048). Incubation with (rh)prorenin significantly increased amnion tissue prorenin levels (2.8 ng/mg total protein, P = 0.001); REN mRNA levels were unchanged. Therefore, amnion explants express small amounts of REN and secrete prorenin protein. Prorenin is also taken up by amnion. We postulate that the amniotic renin angiotensin system (RAS) alters pregnancy outcome through effects on gestation length and amniotic fluid volume. Since human amnion can take up and secrete prorenin protein, the activity of both amnion and amniotic fluid RASs can be amplified by prorenin produced by other intrauterine tissues.
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Affiliation(s)
- Kirsty G Pringle
- Mothers and Babies Research Centre, Hunter Medical Research Institute, John Hunter Hospital & School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, New South Wales, Australia
| | - Yu Wang
- Mothers and Babies Research Centre, Hunter Medical Research Institute, John Hunter Hospital & School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, New South Wales, Australia
| | - Eugenie R Lumbers
- Mothers and Babies Research Centre, Hunter Medical Research Institute, John Hunter Hospital & School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, New South Wales, Australia
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Singh AK, Liu Y, Riederer B, Engelhardt R, Thakur BK, Soleimani M, Seidler U. Molecular transport machinery involved in orchestrating luminal acid-induced duodenal bicarbonate secretion in vivo. J Physiol 2013; 591:5377-91. [PMID: 24018950 DOI: 10.1113/jphysiol.2013.254854] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The duodenal villus brush border membrane expresses several ion transporters and/or channels, including the solute carrier 26 anion transporters Slc26a3 (DRA) and Slc26a6 (PAT-1), the Na(+)/H(+) exchanger isoform 3 (NHE3), as well as the anion channels cystic fibrosis transmembrane conductance regulator (CFTR) and Slc26a9. Using genetically engineered mouse models lacking Scl26a3, Slc26a6, Slc26a9 or Slc9a3 (NHE3), the study was carried out to assess the role of these transporters in mediating the protective duodenal bicarbonate secretory response (DBS-R) to luminal acid; and to compare it to their role in DBS-R elicited by the adenylyl cyclase agonist forskolin. While basal DBS was reduced in the absence of any of the three Slc26 isoforms, the DBS-R to forskolin was not altered. In contrast, the DBS-R to a 5 min exposure to luminal acid (pH 2.5) was strongly reduced in the absence of Slc26a3 or Slc26a9, but not Slc26a6. CFTR inhibitor [CFTR(Inh)-172] reduced the first phase of the acid-induced DBS-R, while NHE3 inhibition (or knockout) abolished the sustained phase of the DBS-R. Luminal acid exposure resulted in the activation of multiple intracellular signalling pathways, including SPAK, AKT and p38 phosphorylation. It induced a biphasic trafficking of NHE3, first rapidly into the brush border membrane, followed by endocytosis in the later stage. We conclude that the long-lasting DBS-R to luminal acid exposure activates multiple duodenocyte signalling pathways and involves changes in trafficking and/or activity of CFTR, Slc26 isoforms Slc26a3 and Slc26a9, and NHE3.
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Affiliation(s)
- Anurag Kumar Singh
- Prof. Dr. U. Seidler: Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Carl-Neuberg-Straße 1, D-30625 Germany.
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Björkman E, Edebo A, Casselbrant A, Helander HF, Bratlie SO, Vieth M, Fändriks L. The renin-angiotensin system in the esophageal mucosa of healthy subjects and patients with reflux disease. Scand J Gastroenterol 2013; 48:147-59. [PMID: 23270416 DOI: 10.3109/00365521.2012.749510] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
OBJECTIVE Components of the renin-angiotensin system (RAS) were recently discovered in the esophagus, which could be of interest in relation to gastroesophageal reflux disease (GERD). The present study was undertaken to confirm and further investigate the expression of RAS in healthy and refluxed exposed human esophageal mucosae. METHODS Esophageal biopsies were obtained from healthy subjects (n = 34) and individuals with erosive reflux disease (ERD, n = 28). Evaluation of general morphology and histological signs of reflux as well as investigation of gene transcript, protein expression and localization of various RAS components using RT-PCR, ELISA, western blot and immunohistochemistry were performed. Physiological effects of the AT2R were investigated in Ussing chamber experiments. RESULTS The study confirmed histological signs of reflux in ERD and expression of ACE, AT1R, AT2R and CatD in all examined specimens. In addition, the main effector peptide AngII, the pro-hormone AGT, the Mas receptor and the angiotensin-forming enzymes renin, CMA, CatG and NEP were present. Individuals with reflux disease had higher transcription activity of ACE and AT1R, increased protein levels of AT2R and lower levels of MasR. AT2R stimulation increased the ion currents in healthy epithelium, whereas epithelium from individuals with reflux disease exhibited no significant response. CONCLUSIONS The study demonstrated that a local RAS is present in the human esophageal epithelium. Some RAS components were significantly altered in individuals diagnosed with ERD suggesting involvement in the pathophysiology of GERD.
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Affiliation(s)
- Eleonora Björkman
- Department of Gastrosurgical Research and Education, Institute of Clinical Sciences, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
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Queiroz-Leite GD, Peruzzetto MC, Neri EA, Rebouças NA. Transcriptional regulation of the Na⁺/H⁺ exchanger NHE3 by chronic exposure to angiotensin II in renal epithelial cells. Biochem Biophys Res Commun 2011; 409:470-6. [PMID: 21600882 DOI: 10.1016/j.bbrc.2011.05.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Accepted: 05/04/2011] [Indexed: 11/27/2022]
Abstract
Angiotensin II (Ang II) exerts an acute bimodal effect on proximal tubule NHE3: while low doses stimulate the exchanger, high doses inhibit it. In the present study, we have investigated the chronic effects of Ang II on NHE3 expression and transcriptional regulation. Treatment of a tubular epithelial cell line, OKP, with Ang II 10(-11)M significantly increased NHE protein expression and mRNA levels, without evidence of bimodal effect. No change in mRNA half-life was detected, but transient transfection studies showed a significant increase in NHE3 promoter activity. Binding sites for Sp1/Egr-1 and AP2 transcription factors of the NHE3 proximal promoter were mutated and we observed that the Sp1/Egr-1 binding site integrity is necessary for Ang II stimulatory effects. Inhibition of cytochrome P450, PI3K, PKA and MAPK pathways prevented the Ang II stimulatory effect on the NHE3 promoter activity. Taking all the results together, our data reveal that chronic Ang II treatment exerts a stimulatory effect on NHE3 expression and promoter activity. The Ang II up-regulation of the NHE3 promoter activity appears to involve the Sp1/Egr-1 binding site and the interplay of several intracellular signaling pathways.
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Affiliation(s)
- Gabriella D Queiroz-Leite
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
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Saksena S, Tyagi S, Goyal S, Gill RK, Alrefai WA, Ramaswamy K, Dudeja PK. Stimulation of apical Cl⁻/HCO₃⁻(OH⁻) exchanger, SLC26A3 by neuropeptide Y is lipid raft dependent. Am J Physiol Gastrointest Liver Physiol 2010; 299:G1334-43. [PMID: 20884887 PMCID: PMC3006247 DOI: 10.1152/ajpgi.00039.2010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Neuropeptide Y (NPY), an important proabsorptive hormone of the gastrointestinal tract has been shown to inhibit chloride secretion and stimulate NaCl absorption. However, mechanisms underlying the proabsorptive effects of NPY are not fully understood. The present studies were designed to examine the direct effects of NPY on apical Cl⁻/HCO₃⁻(OH⁻) exchange activity and the underlying mechanisms involved utilizing Caco2 cells. Our results showed that NPY (100 nM, 30 min) significantly increased Cl⁻/HCO₃⁻(OH⁻) exchange activity (∼2-fold). Selective NPY/Y1 or Y2 receptor agonists mimicked the effects of NPY. NPY-mediated stimulation of Cl⁻/HCO₃⁻(OH⁻) exchange activity involved the ERK1/2 MAP kinase-dependent pathway. Cell surface biotinylation studies showed that NPY does not alter DRA (apical Cl⁻/HCO₃⁻(OH⁻) exchanger) surface expression, ruling out the involvement of membrane trafficking events. Interestingly, DRA was found to be predominantly expressed in the detergent-insoluble (DI) and low-density fractions (LDF) of human colonic apical membrane vesicles (AMVs) representing lipid rafts. Depletion of membrane cholesterol by methyl-β-cyclodextrin (MβCD, 10 mM, 1 h) remarkably decreased DRA expression in the DI fractions. Similar results were obtained in Triton-X 100-treated Caco2 plasma membranes. DRA association with lipid rafts in the DI and LDF fractions of Caco2 cells was significantly enhanced (∼45%) by NPY compared with control. MβCD significantly decreased Cl⁻/HCO₃⁻(OH⁻) exchange activity in Caco2 cells as measured by DIDS- or niflumic acid-sensitive ³⁶Cl⁻ uptake (∼50%). Our results demonstrate that NPY modulates Cl⁻/HCO₃⁻(OH⁻) exchange activity by enhancing the association of DRA with lipid rafts, thereby resulting in an increase in Cl⁻/HCO₃⁻(OH⁻) exchange activity. Our findings suggest that the alteration in the association of DRA with lipid rafts may contribute to the proabsorptive effects of NPY in the human intestine.
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Affiliation(s)
- Seema Saksena
- Dept. of Medicine, University of Illinois at Chicago and Jesse Brown Veterans Affairs Medical Center, Illinois 60612, USA.
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Sansom SE, Nuovo GJ, Martin MM, Kotha SR, Parinandi NL, Elton TS. miR-802 regulates human angiotensin II type 1 receptor expression in intestinal epithelial C2BBe1 cells. Am J Physiol Gastrointest Liver Physiol 2010; 299:G632-42. [PMID: 20558762 PMCID: PMC2950689 DOI: 10.1152/ajpgi.00120.2010] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Accepted: 06/15/2010] [Indexed: 01/31/2023]
Abstract
Studies have demonstrated that angiotensin II (Ang II) can regulate intestinal fluid and electrolyte transport and control intestinal wall muscular activity. Ang II is also a proinflammatory mediator that participates in inflammatory responses such as apoptosis, angiogenesis, and vascular remodeling; accumulating evidence suggests that this hormone may be involved in gastrointestinal (GI) inflammation and carcinogenesis. Ang II binds to two distinct G protein-coupled receptor subtypes, the AT(1)R and AT(2)R, which are widely expressed in the GI system. Together these studies suggest that Ang II-AT(1)R/-AT(2)R actions may play an important role in GI tract physiology and pathophysiology. Currently it is not known whether miRNAs can regulate the expression of the human AT(1)R (hAT(1)R) in the GI system. PCR and in situ hybridization experiments demonstrated that miR-802 was abundantly expressed in human colon and intestine. Luciferase reporter assays demonstrated that miR-802 could directly interact with the bioinformatics-predicted target site harbored within the 3'-untranslated region of the hAT(1)R mRNA. To validate that the levels of miR-802 were physiologically relevant in the GI system, we demonstrated that miR-802 "loss-of-function" experiments resulted in augmented hAT(1)R levels and enhanced Ang II-induced signaling in a human intestinal epithelial cell line. These results suggest that miR-802 can modulate the expression of the hAT(1)R in the GI tract and ultimately play a role in regulating the biological efficacy of Ang II in this system.
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Affiliation(s)
- Sarah E Sansom
- Davis Heart and Lung Research Institute, Department of Pathology, The Ohio State Univ., Columbus, 43210, USA
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