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Becker HM, Seidler UE. Bicarbonate secretion and acid/base sensing by the intestine. Pflugers Arch 2024; 476:593-610. [PMID: 38374228 PMCID: PMC11006743 DOI: 10.1007/s00424-024-02914-3] [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: 11/16/2023] [Revised: 01/15/2024] [Accepted: 01/17/2024] [Indexed: 02/21/2024]
Abstract
The transport of bicarbonate across the enterocyte cell membrane regulates the intracellular as well as the luminal pH and is an essential part of directional fluid movement in the gut. Since the first description of "active" transport of HCO3- ions against a concentration gradient in the 1970s, the fundamental role of HCO3- transport for multiple intestinal functions has been recognized. The ion transport proteins have been identified and molecularly characterized, and knockout mouse models have given insight into their individual role in a variety of functions. This review describes the progress made in the last decade regarding novel techniques and new findings in the molecular regulation of intestinal HCO3- transport in the different segments of the gut. We discuss human diseases with defects in intestinal HCO3- secretion and potential treatment strategies to increase luminal alkalinity. In the last part of the review, the cellular and organismal mechanisms for acid/base sensing in the intestinal tract are highlighted.
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Affiliation(s)
- Holger M Becker
- Department of Gastroenterology, Hannover Medical School, 30625, Hannover, Germany
| | - Ursula E Seidler
- Department of Gastroenterology, Hannover Medical School, 30625, Hannover, Germany.
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2
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Salari A, Xiu R, Amiri M, Pallenberg ST, Schreiber R, Dittrich AM, Tümmler B, Kunzelmann K, Seidler U. The Anion Channel TMEM16a/Ano1 Modulates CFTR Activity, but Does Not Function as an Apical Anion Channel in Colonic Epithelium from Cystic Fibrosis Patients and Healthy Individuals. Int J Mol Sci 2023; 24:14214. [PMID: 37762516 PMCID: PMC10531629 DOI: 10.3390/ijms241814214] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 09/08/2023] [Accepted: 09/11/2023] [Indexed: 09/29/2023] Open
Abstract
Studies in human colonic cell lines and murine intestine suggest the presence of a Ca2+-activated anion channel, presumably TMEM16a. Is there a potential for fluid secretion in patients with severe cystic fibrosis transmembrane conductance regulator (CFTR) mutations by activating this alternative pathway? Two-dimensional nondifferentiated colonoid-myofibroblast cocultures resembling transit amplifying/progenitor (TA/PE) cells, as well as differentiated monolayer (DM) cultures resembling near-surface cells, were established from both healthy controls (HLs) and patients with severe functional defects in the CFTR gene (PwCF). F508del mutant and CFTR knockout (null) mice ileal and colonic mucosa was also studied. HL TA/PE monolayers displayed a robust short-circuit current response (ΔIeq) to UTP (100 µM), forskolin (Fsk, 10 µM) and carbachol (CCH, 100 µM), while ΔIeq was much smaller in differentiated monolayers. The selective TMEM16a inhibitor Ani9 (up to 30 µM) did not alter the response to luminal UTP, significantly decreased Fsk-induced ΔIeq, and significantly increased CCH-induced ΔIeq in HL TA/PE colonoid monolayers. The PwCF TA/PE and the PwCF differentiated monolayers displayed negligible agonist-induced ΔIeq, without a significant effect of Ani9. When TMEM16a was localized in intracellular structures, a staining in the apical membrane was not detected. TMEM16a is highly expressed in human colonoid monolayers resembling transit amplifying cells of the colonic cryptal neck zone, from both HL and PwCF. While it may play a role in modulating agonist-induced CFTR-mediated anion currents, it is not localized in the apical membrane, and it has no function as an apical anion channel in cystic fibrosis (CF) and healthy human colonic epithelium.
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Affiliation(s)
- Azam Salari
- Department of Gastroenterology, Hannover Medical School, 30625 Hannover, Germany; (A.S.); (R.X.); (M.A.)
| | - Renjie Xiu
- Department of Gastroenterology, Hannover Medical School, 30625 Hannover, Germany; (A.S.); (R.X.); (M.A.)
| | - Mahdi Amiri
- Department of Gastroenterology, Hannover Medical School, 30625 Hannover, Germany; (A.S.); (R.X.); (M.A.)
| | - Sophia Theres Pallenberg
- Department of Pediatric Pneumonology, Allergology and Neonatology, Hannover Medical School, 30625 Hannover, Germany (A.-M.D.)
| | - Rainer Schreiber
- Institute of Physiology, University of Regensburg, 93040 Regensburg, Germany; (R.S.); (K.K.)
| | - Anna-Maria Dittrich
- Department of Pediatric Pneumonology, Allergology and Neonatology, Hannover Medical School, 30625 Hannover, Germany (A.-M.D.)
| | - Burkhard Tümmler
- Department of Pediatric Pneumonology, Allergology and Neonatology, Hannover Medical School, 30625 Hannover, Germany (A.-M.D.)
| | - Karl Kunzelmann
- Institute of Physiology, University of Regensburg, 93040 Regensburg, Germany; (R.S.); (K.K.)
| | - Ursula Seidler
- Department of Gastroenterology, Hannover Medical School, 30625 Hannover, Germany; (A.S.); (R.X.); (M.A.)
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Nickerson AJ, Rajendran VM. Dietary Na + depletion up-regulates NKCC1 expression and enhances electrogenic Cl - secretion in rat proximal colon. Cell Mol Life Sci 2023; 80:209. [PMID: 37458846 PMCID: PMC11073443 DOI: 10.1007/s00018-023-04857-x] [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: 09/13/2022] [Revised: 06/25/2023] [Accepted: 07/04/2023] [Indexed: 07/20/2023]
Abstract
The corticosteroid hormone, aldosterone, markedly enhances K+ secretion throughout the colon, a mechanism critical to its role in maintaining overall K+ balance. Previous studies demonstrated that basolateral NKCC1 was up-regulated by aldosterone in the distal colon specifically to support K+ secretion-which is distinct from the more well-established role of NKCC1 in supporting luminal Cl- secretion. However, considerable segmental variability exists between proximal and distal colonic ion transport processes, especially concerning their regulation by aldosterone. Furthermore, delineating such region-specific effects has important implications for the management of various gastrointestinal pathologies. Experiments were therefore designed to determine whether aldosterone similarly up-regulates NKCC1 in the proximal colon to support K+ secretion. Using dietary Na+ depletion as a model of secondary hyperaldosteronism in rats, we found that proximal colon NKCC1 expression was indeed enhanced in Na+-depleted (i.e., hyperaldosteronemic) rats. Surprisingly, electrogenic K+ secretion was not detectable by short-circuit current (ISC) measurements in response to either basolateral bumetanide (NKCC1 inhibitor) or luminal Ba2+ (non-selective K+ channel blocker), despite enhanced K+ secretion in Na+-depleted rats, as measured by 86Rb+ fluxes. Expression of BK and IK channels was also found to be unaltered by dietary Na+ depletion. However, bumetanide-sensitive basal and agonist-stimulated Cl- secretion (ISC) were significantly enhanced by Na+ depletion, as was CFTR Cl- channel expression. These data suggest that NKCC1-dependent secretory pathways are differentially regulated by aldosterone in proximal and distal colon. Development of therapeutic strategies in treating pathologies related to aberrant colonic K+/Cl- transport-such as pseudo-obstruction or ulcerative colitis-may benefit from these findings.
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Affiliation(s)
- Andrew J Nickerson
- Departments of Physiology, Pharmacology and Neuroscience, West Virginia University School of Medicine, Morgantown, WV, USA
- Departments of Biochemistry and Molecular Medicine, West Virginia University School of Medicine, 1 Medical Center Drive, Morgantown, WV, 26506, USA
- University of Pittsburgh, S929 Scaife Hall, 3550 Terrace Street, Pittsburgh, PA, USA
| | - Vazhaikkurichi M Rajendran
- Departments of Biochemistry and Molecular Medicine, West Virginia University School of Medicine, 1 Medical Center Drive, Morgantown, WV, 26506, USA.
- Department of Medicine, West Virginia University School of Medicine, Morgantown, WV, USA.
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Hegyi P, Seidler U, Kunzelmann K. CFTR-beyond the airways: Recent findings on the role of the CFTR channel in the pancreas, the intestine and the kidneys. J Cyst Fibros 2023; 22 Suppl 1:S17-S22. [PMID: 36621373 DOI: 10.1016/j.jcf.2022.12.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 12/31/2022] [Accepted: 12/31/2022] [Indexed: 01/09/2023]
Abstract
With increased longevity of patients suffering from cystic fibrosis, and widespread lung transplantation facilities, the sequelae of defective CFTR in other organs than the airways come to the fore. This minireview highlights recent scientific progress in the understanding of CFTR function in the pancreas, the intestine and the kidney, and explores potential therapeutic strategies to combat defective CFTR function in these organs.
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Affiliation(s)
- Peter Hegyi
- Institute for Translational Medicine, Medical School, University of Pécs, 7624 Pécs, Hungary; Center for Translational Medicine and Institute of Pancreatic Diseases, Semmelweis University, 1085 Budapest, Hungary; Translational Pancreatology Research Group, Interdisciplinary Centre of Excellence for Research Development and Innovation, University of Szeged, 6725 Szeged, Hungary
| | - Ursula Seidler
- Department of Gastroenterology, Hannover Medical School, 30625 Hannover, Germany.
| | - Karl Kunzelmann
- Institute of Physiology, Regensburg University, 93040 Regensburg, Germany
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Nylander O, Sjöblom M, Sedin J, Dahlgren D. Effects of α2-adrenoceptor stimulation on luminal alkalinisation and net fluid flux in rat duodenum. PLoS One 2022; 17:e0273208. [PMID: 36006975 PMCID: PMC9409570 DOI: 10.1371/journal.pone.0273208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 08/03/2022] [Indexed: 12/03/2022] Open
Abstract
The sympathetic nervous system is highly involved in the regulation of gastrointestinal functions such as luminal alkalinisation and fluid absorption. However, the exact mechanisms are not clear. This study aimed to delineate how α2-adrenergic receptor stimulation reduces duodenal luminal alkalinisation and induces net fluid absorption. This was tested by perfusing the duodenum of anesthetized rats with isotonic solutions devoid of Cl- and/or Na+, in the absence and presence of the α2-adrenoceptor agonist clonidine. The clonidine was also studied in rats treated with dimethylamiloride (a Na+/H+ exchange inhibitor), vasoactive intestinal peptide, and the nicotinic receptor antagonist hexamethonium. Clonidine reduced luminal alkalinisation and induced net fluid absorption. The Cl--free solution decreased luminal alkalinisation and abolished net fluid absorption, but did not prevent clonidine from doing so. Both the Na+-free solution and luminal dimethylamiloride increased luminal alkalinisation and abolished net fluid absorption, effects counteracted by clonidine. The NaCl-free solution (D-mannitol) did not affect luminal alkalinisation, but reduced net fluid absorption. Clonidine reduced luminal alkalinisation and induced net fluid absorption in rats perfused luminally with mannitol. However, clonidine did not affect the vasoactive intestinal peptide-induced increase in luminal alkalinisation or fluid secretion. Pre-treatment with hexamethonium abolished the effects of clonidine on luminal alkalinisation and net fluid flux. In summary, our in vivo experiments showed that clonidine-induced reduction in luminal alkalinisation and induction of net fluid absorption was unrelated to luminal Na+ and Cl-, or to apical Na+/H+ or Cl-/HCO3- exchangers. Instead, clonidine seems to exert its effects via suppression of nicotinic receptor-activated acetylcholine secretomotor neurons.
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Affiliation(s)
- Olof Nylander
- Division of Physiology, Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Markus Sjöblom
- Division of Physiology, Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - John Sedin
- Division of Physiology, Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - David Dahlgren
- Division of Physiology, Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
- * E-mail:
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Keely SJ, Barrett KE. Intestinal secretory mechanisms and diarrhea. Am J Physiol Gastrointest Liver Physiol 2022; 322:G405-G420. [PMID: 35170355 PMCID: PMC8917926 DOI: 10.1152/ajpgi.00316.2021] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 02/07/2022] [Accepted: 02/09/2022] [Indexed: 01/31/2023]
Abstract
One of the primary functions of the intestinal epithelium is to transport fluid and electrolytes to and from the luminal contents. Under normal circumstances, absorptive and secretory processes are tightly regulated such that absorption predominates, thereby enabling conservation of the large volumes of water that pass through the intestine each day. However, in conditions of secretory diarrhea, this balance becomes dysregulated, so that fluid secretion, driven primarily by Cl- secretion, overwhelms absorptive capacity, leading to increased loss of water in the stool. Secretory diarrheas are common and include those induced by pathogenic bacteria and viruses, allergens, and disruptions to bile acid homeostasis, or as a side effect of many drugs. Here, we review the cellular and molecular mechanisms by which Cl- and fluid secretion in the intestine are regulated, how these mechanisms become dysregulated in conditions of secretory diarrhea, currently available and emerging therapeutic approaches, and how new strategies to exploit intestinal secretory mechanisms are successfully being used in the treatment of constipation.
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Affiliation(s)
- Stephen J Keely
- School of Pharmacy and Biomolecular Sciences, Royal College of Surgeons in Ireland, University of Medicine and Health Sciences, Dublin, Ireland
| | - Kim E Barrett
- Department of Medicine, School of Medicine, University of California San Diego, La Jolla, California
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, Davis, California
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Manneck D, Manz G, Braun HS, Rosendahl J, Stumpff F. The TRPA1 Agonist Cinnamaldehyde Induces the Secretion of HCO 3- by the Porcine Colon. Int J Mol Sci 2021; 22:ijms22105198. [PMID: 34068986 PMCID: PMC8156935 DOI: 10.3390/ijms22105198] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 05/09/2021] [Accepted: 05/10/2021] [Indexed: 02/07/2023] Open
Abstract
A therapeutic potential of the TRPA1 channel agonist cinnamaldehyde for use in inflammatory bowel disease is emerging, but the mechanisms are unclear. Semi-quantitative qPCR of various parts of the porcine gastrointestinal tract showed that mRNA for TRPA1 was highest in the colonic mucosa. In Ussing chambers, 1 mmol·L-1 cinnamaldehyde induced increases in short circuit current (ΔIsc) and conductance (ΔGt) across the colon that were higher than those across the jejunum or after 1 mmol·L-1 thymol. Lidocaine, amiloride or bumetanide did not change the response. The application of 1 mmol·L-1 quinidine or the bilateral replacement of 120 Na+, 120 Cl- or 25 HCO3- reduced ΔGt, while the removal of Ca2+ enhanced ΔGt with ΔIsc numerically higher. ΔIsc decreased after 0.5 NPPB, 0.01 indometacin and the bilateral replacement of 120 Na+ or 25 HCO3-. The removal of 120 Cl- had no effect. Cinnamaldehyde also activates TRPV3, but comparative measurements involving patch clamp experiments on overexpressing cells demonstrated that much higher concentrations are required. We suggest that cinnamaldehyde stimulates the secretion of HCO3- via apical CFTR and basolateral Na+-HCO3- cotransport, preventing acidosis and damage to the epithelium and the colonic microbiome. Signaling may involve the opening of TRPA1, depolarization of the epithelium and a rise in PGE2 following a lower uptake of prostaglandins via OATP2A1.
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Affiliation(s)
- David Manneck
- Department of Veterinary Medicine, Institute of Veterinary Physiology, Freie Universität Berlin, Oertzenweg 19b, 14163 Berlin, Germany; (D.M.); (G.M.)
| | - Gisela Manz
- Department of Veterinary Medicine, Institute of Veterinary Physiology, Freie Universität Berlin, Oertzenweg 19b, 14163 Berlin, Germany; (D.M.); (G.M.)
| | - Hannah-Sophie Braun
- PerformaNat GmbH, Hohentwielsteig 6, 14163 Berlin, Germany; (H.-S.B.); (J.R.)
| | - Julia Rosendahl
- PerformaNat GmbH, Hohentwielsteig 6, 14163 Berlin, Germany; (H.-S.B.); (J.R.)
| | - Friederike Stumpff
- Department of Veterinary Medicine, Institute of Veterinary Physiology, Freie Universität Berlin, Oertzenweg 19b, 14163 Berlin, Germany; (D.M.); (G.M.)
- Correspondence: ; Tel.: +49-30-838-62595
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Wang J, Wang W, Wang H, Tuo B. Physiological and Pathological Functions of SLC26A6. Front Med (Lausanne) 2021; 7:618256. [PMID: 33553213 PMCID: PMC7859274 DOI: 10.3389/fmed.2020.618256] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 12/30/2020] [Indexed: 12/26/2022] Open
Abstract
Solute Carrier Family 26 (SLC26) is a conserved anion transporter family with 10 members in human (SLC26A1-A11, A10 being a pseudogene). All SLC26 genes except for SLC26A5 (prestin) are versatile anion exchangers with notable ability to transport a variety of anions. SLC26A6 has the most extensive exchange functions in the SLC26 family and is widely expressed in various organs and tissues of mammals. SLC26A6 has some special properties that make it play a particularly important role in ion homeostasis and acid-base balance. In the past few years, the function of SLC26A6 in the diseases has received increasing attention. SLC26A6 not only participates in the development of intestinal and pancreatic diseases but also serves a significant role in mediating nephrolithiasis, fetal skeletal dysplasia and arrhythmia. This review aims to explore the role of SLC26A6 in physiology and pathophysiology of relative mammalian organs to guide in-depth studies about related diseases of human.
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Affiliation(s)
- Juan Wang
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Wenkang Wang
- Department of Critical Care Medicine of the Third Affiliated Hospital (The First People's Hospital of Zunyi City), Zunyi Medical University, Zunyi, China
| | - Hui Wang
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Biguang Tuo
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
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Negro A, Verzicco I, Tedeschi S, Campanini N, Zanelli M, Negri E, Farnetti E, Nicoli D, Palladini B, Santi R, Cunzi D, Calvi A, Coghi P, Gerra L, Volpi R, Graiani G, Cabassi A. Case Report: Irreversible Watery Diarrhea, Severe Metabolic Acidosis, Hypokalemia and Achloridria Syndrome Related to Vasoactive Intestinal Peptide Secreting Malignant Pheochromocytoma. Front Endocrinol (Lausanne) 2021; 12:652045. [PMID: 33815297 PMCID: PMC8010837 DOI: 10.3389/fendo.2021.652045] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 03/01/2021] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Pheochromocytoma (PHEO) clinical manifestations generally mirror excessive catecholamines secretion; rarely the clinical picture may reflect secretion of other hormones. Watery diarrhea, hypokalemia and achlorhydria (WDHA) is a rare syndrome related to excessive secretion of vasoactive intestinal peptide (VIP). CLINICAL CASE A 73-year-old hypotensive man affected by adrenal PHEO presented with weight loss and watery diarrhea associated with hypokalemia, hyperchloremic metabolic acidosis (anion gap 15 mmol/l) and a negative urinary anion gap. Abdominal computed tomography scan showed a right adrenal PHEO, 8.1 cm in maximum diameter, with tracer uptake on 68GaDOTA-octreotate positron emission tomography. Metastasis in lumbar region and lung were present. Both chromogranin A and VIP levels were high (more than10 times the normal value) with slightly elevated urine normetanephrine and metanephrine excretion. Right adrenalectomy was performed and a somatostatin analogue therapy with lanreotide started. Immunostaining showed chromogranin A and VIP co-expression, with weak somatostatin-receptor-2A positivity. In two months, patient clinical conditions deteriorated with severe WDHA and multiple liver and lung metastasis. Metabolic acidosis and hypokalemia worsened, leading to hemodynamic shock and exitus. CONCLUSIONS A rare case of WDHA syndrome caused by malignant VIP-secreting PHEO was diagnosed. High levels of circulating VIP were responsible of the rapidly evolving clinical picture with massive dehydration and weight loss along with severe hyperchloremic metabolic acidosis and hypokalemia due to the profuse untreatable diarrhea. The rescue treatment with lanreotide was unsuccessful because of the paucity of somatostatin-receptor-2A on VIP-secreting PHEO chromaffin cells.
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Affiliation(s)
- Aurelio Negro
- Internal Medicine and Secondary Hypertension Center, Ospedale Sant’Anna di Castelnovo Ne’ Monti, Azienda Unità sanitaria Locale – IRCCS di Reggio Emilia, Reggio Emilia, Italy
| | - Ignazio Verzicco
- Centro Ipertensione Arteriosa e Studio Malattie Cardiorenali, S.S. Fisiopatologia Medica, Clinica Medica Generale e Terapia Medica, Parma, Italy
| | - Stefano Tedeschi
- Centro Ipertensione Arteriosa e Studio Malattie Cardiorenali, S.S. Fisiopatologia Medica, Clinica Medica Generale e Terapia Medica, Parma, Italy
| | - Nicoletta Campanini
- Pathology Unit, Department of Medicine and Surgery, University Hospital of Parma, Parma, Italy
| | - Magda Zanelli
- Pathology Unit, Ospedale Sant’Anna di Castelnovo Ne’ Monti, Azienda Unità sanitaria Locale – IRCCS di Reggio Emilia, Reggio Emilia, Italy
| | - Emanuele Negri
- High Care Internal Medicine Unit, Ospedale Sant’Anna di Castelnovo Ne’ Monti, Azienda Unità sanitaria Locale – IRCCS di Reggio Emilia, Reggio Emilia, Italy
| | - Enrico Farnetti
- Molecular Biology Laboratory, Ospedale Sant’Anna di Castelnovo Ne’ Monti, Azienda Unità sanitaria Locale – IRCCS di Reggio Emilia, Reggio Emilia, Italy
| | - Davide Nicoli
- Molecular Biology Laboratory, Ospedale Sant’Anna di Castelnovo Ne’ Monti, Azienda Unità sanitaria Locale – IRCCS di Reggio Emilia, Reggio Emilia, Italy
| | - Barbara Palladini
- Centro Ipertensione Arteriosa e Studio Malattie Cardiorenali, S.S. Fisiopatologia Medica, Clinica Medica Generale e Terapia Medica, Parma, Italy
| | - Rosaria Santi
- Internal Medicine and Secondary Hypertension Center, Ospedale Sant’Anna di Castelnovo Ne’ Monti, Azienda Unità sanitaria Locale – IRCCS di Reggio Emilia, Reggio Emilia, Italy
- High Care Internal Medicine Unit, Ospedale Sant’Anna di Castelnovo Ne’ Monti, Azienda Unità sanitaria Locale – IRCCS di Reggio Emilia, Reggio Emilia, Italy
| | - Davide Cunzi
- Internal Medicine and Secondary Hypertension Center, Ospedale Sant’Anna di Castelnovo Ne’ Monti, Azienda Unità sanitaria Locale – IRCCS di Reggio Emilia, Reggio Emilia, Italy
- Centro Ipertensione Arteriosa e Studio Malattie Cardiorenali, S.S. Fisiopatologia Medica, Clinica Medica Generale e Terapia Medica, Parma, Italy
| | - Anna Calvi
- Centro Ipertensione Arteriosa e Studio Malattie Cardiorenali, S.S. Fisiopatologia Medica, Clinica Medica Generale e Terapia Medica, Parma, Italy
| | - Pietro Coghi
- Centro Ipertensione Arteriosa e Studio Malattie Cardiorenali, S.S. Fisiopatologia Medica, Clinica Medica Generale e Terapia Medica, Parma, Italy
| | - Luigi Gerra
- Centro Ipertensione Arteriosa e Studio Malattie Cardiorenali, S.S. Fisiopatologia Medica, Clinica Medica Generale e Terapia Medica, Parma, Italy
| | - Riccardo Volpi
- Centro Ipertensione Arteriosa e Studio Malattie Cardiorenali, S.S. Fisiopatologia Medica, Clinica Medica Generale e Terapia Medica, Parma, Italy
| | - Gallia Graiani
- Histology and Histopathology Unit, Dental School, University of Parma, Parma, Italy
| | - Aderville Cabassi
- Centro Ipertensione Arteriosa e Studio Malattie Cardiorenali, S.S. Fisiopatologia Medica, Clinica Medica Generale e Terapia Medica, Parma, Italy
- *Correspondence: Aderville Cabassi,
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Kaji I, Roland JT, Watanabe M, Engevik AC, Goldstein AE, Hodges CA, Goldenring JR. Lysophosphatidic Acid Increases Maturation of Brush Borders and SGLT1 Activity in MYO5B-deficient Mice, a Model of Microvillus Inclusion Disease. Gastroenterology 2020; 159:1390-1405.e20. [PMID: 32534933 PMCID: PMC8240502 DOI: 10.1053/j.gastro.2020.06.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 05/29/2020] [Accepted: 06/03/2020] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIM Myosin VB (MYO5B) is an essential trafficking protein for membrane recycling in gastrointestinal epithelial cells. The inactivating mutations of MYO5B cause the congenital diarrheal disease, microvillus inclusion disease (MVID). MYO5B deficiency in mice causes mislocalization of SGLT1 and NHE3, but retained apical function of CFTR, resulting in malabsorption and secretory diarrhea. Activation of lysophosphatidic acid (LPA) receptors can improve diarrhea, but the effect of LPA on MVID symptoms is unclear. We investigated whether LPA administration can reduce the epithelial deficits in MYO5B-knockout mice. METHODS Studies were conducted with tamoxifen-induced, intestine-specific knockout of MYO5B (VilCreERT2;Myo5bflox/flox) and littermate controls. Mice were given LPA, an LPAR2 agonist (GRI977143), or vehicle for 4 days after a single injection of tamoxifen. Apical SGLT1 and CFTR activities were measured in Üssing chambers. Intestinal tissues were collected, and localization of membrane transporters was evaluated by immunofluorescence analysis in tissue sections and enteroids. RNA sequencing and enrichment analysis were performed with isolated jejunal epithelial cells. RESULTS Daily administration of LPA reduced villus blunting, frequency of multivesicular bodies, and levels of cathepsins in intestinal tissues of MYO5B-knockout mice compared with vehicle administration. LPA partially restored the brush border height and the localization of SGLT1 and NHE3 in small intestine of MYO5B-knockout mice and enteroids. The SGLT1-dependent short-circuit current was increased and abnormal CFTR activities were decreased in jejunum from MYO5B-knockout mice given LPA compared with vehicle. CONCLUSIONS LPA may regulate a MYO5B-independent trafficking mechanism and brush border maturation, and therefore be developed for treatment of MVID.
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Affiliation(s)
- Izumi Kaji
- Section of Surgical Sciences, Vanderbilt University Medical Center, Nashville, Tennessee; Epithelial Biology Center, Vanderbilt University School of Medicine, Nashville, Tennessee.
| | - Joseph T. Roland
- Section of Surgical Sciences, Vanderbilt University Medical Center, Sapporo, Japan,Epithelial Biology Center, Vanderbilt University School of Medicine, Sapporo, Japan
| | | | - Amy C. Engevik
- Section of Surgical Sciences, Vanderbilt University Medical Center, Sapporo, Japan,Epithelial Biology Center, Vanderbilt University School of Medicine, Sapporo, Japan
| | - Anna E. Goldstein
- Section of Surgical Sciences, Vanderbilt University Medical Center, Sapporo, Japan,Epithelial Biology Center, Vanderbilt University School of Medicine, Sapporo, Japan
| | - Craig A. Hodges
- Cystic Fibrosis Mouse Models Resource Center, Case Western Reserve University, Cleveland, OH
| | - James R. Goldenring
- Section of Surgical Sciences, Vanderbilt University Medical Center, Sapporo, Japan,Epithelial Biology Center, Vanderbilt University School of Medicine, Sapporo, Japan,Cell and Developmental Biology, Vanderbilt University School of Medicine, Sapporo, Japan,Nashville Veterans Affairs Medical Center, Nashville TN
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11
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Parathyroid hormone increases CFTR expression and function in Caco-2 intestinal epithelial cells. Biochem Biophys Res Commun 2020; 523:816-821. [DOI: 10.1016/j.bbrc.2019.12.106] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 12/31/2019] [Indexed: 12/29/2022]
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12
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Xu J, Zeug A, Riederer B, Yeruva S, Griesbeck O, Daniel H, Tuo B, Ponimaskin E, Dong H, Seidler U. Calcium-sensing receptor regulates intestinal dipeptide absorption via Ca 2+ signaling and IK Ca activation. Physiol Rep 2020; 8:e14337. [PMID: 31960592 PMCID: PMC6971415 DOI: 10.14814/phy2.14337] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Although absorption of di- and tripeptides into intestinal epithelial cells occurs via the peptide transporter 1 (PEPT1, also called solute carrier family 15 member 1 (SLC15A1)), the detailed regulatory mechanisms are not fully understood. We examined: (a) whether dipeptide absorption in villous enterocytes is associated with a rise in cytosolic Ca2+ ([Ca2+ ]cyt ), (b) whether the calcium sensing receptor (CaSR) is involved in dipeptide-elicited [Ca2+ ]cyt signaling, and (c) what potential consequences of [Ca2+ ]cyt signaling may enhance enterocyte dipeptide absorption. Dipeptide Gly-Sar and CaSR agonist spermine markedly raised [Ca2+ ]cyt in villous enterocytes, which was abolished by NPS-2143, a selective CaSR antagonist and U73122, an phospholipase C (PLC) inhibitor. Apical application of Gly-Sar induced a jejunal short-circuit current (Isc), which was reduced by NPS-2143. CaSR expression was identified in the lamina propria and on the basal enterocyte membrane of mouse jejunal mucosa in both WT and Slc15a1-/- animals, but Gly-Sar-induced [Ca2+ ]cyt signaling was significantly decreased in Slc15a1-/- villi. Clotrimazole and TRM-34, two selective blockers of the intermediate conductance Ca2+ -activated K+ channel (IKCa ), but not iberiotoxin, a selective blocker of the large-conductance K+ channel (BKCa ) and apamin, a selective blocker of the small-conductance K+ channel (SKCa ), significantly inhibited Gly-Sar-induced Isc in native tissues. We reveal a novel CaSR-PLC-Ca2+ -IKCa pathway in the regulation of small intestinal dipeptide absorption, which may be exploited as a target for future drug development in human nutritional disorders.
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Affiliation(s)
- Jingyu Xu
- Department of Gastroenterology, Hepatology and EndocrinologyHannover Medical SchoolHannoverGermany
- Research GastroenterologyAffiliated Hospital of Zunyi Medical UniversityZunyiChina
| | - Andre Zeug
- Cellular NeurophysiologyHannover Medical SchoolHannoverGermany
| | - Brigitte Riederer
- Department of Gastroenterology, Hepatology and EndocrinologyHannover Medical SchoolHannoverGermany
| | - Sunil Yeruva
- Department of Gastroenterology, Hepatology and EndocrinologyHannover Medical SchoolHannoverGermany
| | | | - Hannelore Daniel
- Nutritional PhysiologyTechnical University of MunichFreisingGermany
| | - Biguang Tuo
- Research GastroenterologyAffiliated Hospital of Zunyi Medical UniversityZunyiChina
| | | | - Hui Dong
- Department of MedicineUniversity of California, San DiegoLa JollaCAUSA
| | - Ursula Seidler
- Department of Gastroenterology, Hepatology and EndocrinologyHannover Medical SchoolHannoverGermany
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13
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Iwasaki M, Akiba Y, Kaunitz JD. Recent advances in vasoactive intestinal peptide physiology and pathophysiology: focus on the gastrointestinal system. F1000Res 2019; 8. [PMID: 31559013 PMCID: PMC6743256 DOI: 10.12688/f1000research.18039.1] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/05/2019] [Indexed: 12/11/2022] Open
Abstract
Vasoactive intestinal peptide (VIP), a gut peptide hormone originally reported as a vasodilator in 1970, has multiple physiological and pathological effects on development, growth, and the control of neuronal, epithelial, and endocrine cell functions that in turn regulate ion secretion, nutrient absorption, gut motility, glycemic control, carcinogenesis, immune responses, and circadian rhythms. Genetic ablation of this peptide and its receptors in mice also provides new insights into the contribution of VIP towards physiological signaling and the pathogenesis of related diseases. Here, we discuss the impact of VIP on gastrointestinal function and diseases based on recent findings, also providing insight into its possible therapeutic application to diabetes, autoimmune diseases and cancer.
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Affiliation(s)
- Mari Iwasaki
- Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA, USA
| | - Yasutada Akiba
- Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA, USA.,Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Jonathan D Kaunitz
- Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA, USA.,Departments of Medicine and Surgery, UCLA School of Medicine, Los Angeles, CA, USA
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14
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Chen T, Lin R, Avula L, Sarker R, Yang J, Cha B, Tse CM, McNamara G, Seidler U, Waldman S, Snook A, Bijvelds MJC, de Jonge HR, Li X, Donowitz M. NHERF3 is necessary for Escherichia coli heat-stable enterotoxin-induced inhibition of NHE3: differences in signaling in mouse small intestine and Caco-2 cells. Am J Physiol Cell Physiol 2019; 317:C737-C748. [PMID: 31365292 DOI: 10.1152/ajpcell.00351.2018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Enterotoxigenic Escherichia coli (ETEC) is a leading cause of childhood death from diarrhea and the leading cause of Traveler's diarrhea. E. coli heat-stable enterotoxin (ST) is a major virulence factor of ETEC and inhibits the brush border Na/H exchanger NHE3 in producing diarrhea. NHE3 regulation involves multiprotein signaling complexes that form on its COOH terminus. In this study, the hypothesis was tested that ST signals via members of the Na/H exchanger regulatory factor (NHERF) family of scaffolding proteins, NHERF2, which had been previously shown to have a role, and now with concentration on a role for NHERF3. Two models were used: mouse small intestine and Caco-2/BBe cells. In both models, ST rapidly increased intracellular cGMP, inhibited NHE3 activity, and caused a quantitatively similar decrease in apical expression of NHE3. The transport effects were NHERF3 and NHERF2 dependent. Also, mutation of the COOH-terminal amino acids of NHERF3 supported that NHERF3-NHERF2 heterodimerization was likely to account for this dual dependence. The ST increase in cGMP in both models was partially dependent on NHERF3. The intracellular signaling pathways by which ST-cGMP inhibits NHE3 were different in mouse jejunum (activation of cGMP kinase II, cGKII) and Caco-2 cells, which do not express cGKII (elevation of intracellular Ca2+ concentration [Ca2+]i). The ST elevation of [Ca2+]i was from intracellular stores and was dependent on NHERF3-NHERF2. This study shows that intracellular signaling in the same diarrheal model in multiple cell types may be different; this has implications for therapeutic strategies, which often assume that models have similar signaling mechanisms.
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Affiliation(s)
- Tiane Chen
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Ruxian Lin
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Leela Avula
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Rafiquel Sarker
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Jianbo Yang
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Boyoung Cha
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Chung Ming Tse
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - George McNamara
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Ursula Seidler
- Department of Gastroenterology, Hannover Medical School, Hannover, Germany
| | - Scott Waldman
- Division of Clinical Pharmacology, Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Adam Snook
- Division of Clinical Pharmacology, Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Marcel J C Bijvelds
- Department of Gastroenterology and Hepatology, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Hugo R de Jonge
- Department of Gastroenterology and Hepatology, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Xuhang Li
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Mark Donowitz
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
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15
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Vega G, Guequén A, Johansson MEV, Arike L, Martínez-Abad B, Nyström EEL, Scudieri P, Pedemonte N, Millar-Büchner P, Philp AR, Galietta LJ, Hansson GC, Flores CA. Normal Calcium-Activated Anion Secretion in a Mouse Selectively Lacking TMEM16A in Intestinal Epithelium. Front Physiol 2019; 10:694. [PMID: 31263421 PMCID: PMC6585864 DOI: 10.3389/fphys.2019.00694] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 05/16/2019] [Indexed: 01/24/2023] Open
Abstract
Calcium-activated anion secretion is expected to ameliorate cystic fibrosis, a genetic disease that carries an anion secretory defect in exocrine tissues. Human patients and animal models of the disease that present a mild intestinal phenotype have been postulated to bear a compensatory calcium-activated anion secretion in the intestine. TMEM16A is calcium-activated anion channel whose presence in the intestinal epithelium is contradictory. We aim to test the functional expression of TMEM16A using animal models with Cftr and/or Tmem16a intestinal silencing. Expression of TMEM16A was studied in a wild type and intestinal Tmem16a knockout mice by mRNA-seq, mass-spectrometry, q-PCR, Western blotting and immunolocalization. Calcium-activated anion secretion was recorded in the ileum and proximal colon of these animals including intestinal Cftr knockout and double mutants with dual Tmem16a and Cftr intestinal ablation. Mucus homeostasis was studied by immune-analysis of Mucin-2 (Muc2) and survival curves were recorded. Tmem16a transcript was found in intestine. Nevertheless, protein was barely detected in colon samples. Electrophysiological measurements demonstrated that the intestinal deletion of Tmem16a did not change calcium-activated anion secretion induced by carbachol or ATP in ileum and proximal colon. Muc2 architecture was not altered by Tmem16a silencing as was observed when Cftr was deleted from mouse intestine. Tmem16a silencing neither affected animal survival nor modified the lethality observed in the intestinal Cftr-null mouse. Our results demonstrate that TMEM16A function in the murine intestine is not related to electrogenic calcium-activated anion transport and does not affect mucus homeostasis and survival of animals.
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Affiliation(s)
- Génesis Vega
- Centro de Estudios Científicos (CECs), Valdivia, Chile
- Universidad Austral de Chile, Valdivia, Chile
| | - Anita Guequén
- Centro de Estudios Científicos (CECs), Valdivia, Chile
| | | | - Liisa Arike
- Department of Medical Biochemistry, University of Gothenburg, Gothenburg, Sweden
| | | | | | - Paolo Scudieri
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy
| | | | | | - Amber R. Philp
- Centro de Estudios Científicos (CECs), Valdivia, Chile
- Universidad Austral de Chile, Valdivia, Chile
| | - Luis J. Galietta
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy
- Department of Translational Medical Sciences (DISMET), University of Naples Federico II, Naples, Italy
| | - Gunnar C. Hansson
- Department of Medical Biochemistry, University of Gothenburg, Gothenburg, Sweden
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16
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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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17
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Takei Y, Wong MKS, Ando M. Molecular mechanisms for intestinal HCO3− secretion and its regulation by guanylin in seawater-acclimated eels. J Exp Biol 2019; 222:jeb.203539. [DOI: 10.1242/jeb.203539] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 06/03/2019] [Indexed: 01/25/2023]
Abstract
The intestine of marine teleosts secretes HCO3− into the lumen and precipitates Ca2+ and Mg2+ in the imbibed seawater as carbonates to decrease luminal fluid osmolality and facilitate water absorption. However, hormonal regulation of HCO3−secretion is largely unknown. Here, mucosally-added guanylin (GN) increased HCO3− secretion, measured by pH-stat, across isolated seawater-acclimated eel intestine bathed in saline at pH 7.4 (5% CO2). The effect of GN on HCO3− secretion was slower than that on the short-circuit current, and the time-course of the GN effect was similar to that of bumetanide. Mucosal bumetanide and serosal 4,4’-dinitrostilbene-2,2’-disulfonic acid (DNDS) inhibited the GN effect, suggesting an involvement of apical Na+-K+-2Cl− cotransporter (NKCC2) and basolateral Cl−/HCO3− exchanger (AE)/Na+-HCO3− cotransporter (NBC) in the GN effect. As mucosal DNDS failed to inhibit the GN effect, apical DNDS-sensitive AE may not be involved. To identify molecular species of transporters involved in the GN effect, we performed RNA-seq analyses followed by quantitative real-time PCR after transfer of eels to seawater. Among the genes upregulated after seawater transfer, AE genes, draa, b, and pat1a, c, on the apical membrane, and NBC genes, nbce1a, n1, n2a, and a AE gene, sat-1, on the basolateral membrane were candidates involved in HCO3− secretion. Judging from the slow effect of GN, we suggest that GN inhibits NKCC2b on the apical membrane and decreases cytosolic Cl− and Na+, which then activates apical DNDS-insensitive DRAs and basolateral DNDS-sensitive NBCs to enhance transcellular HCO3− flux across the intestinal epithelia of seawater-acclimated eels.
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Affiliation(s)
- Yoshio Takei
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, the University of Tokyo, Kashiwa, Chiba 277-8564, Japan
| | - Marty K. S. Wong
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, the University of Tokyo, Kashiwa, Chiba 277-8564, Japan
| | - Masaaki Ando
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, the University of Tokyo, Kashiwa, Chiba 277-8564, Japan
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18
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Madácsy T, Pallagi P, Maleth J. Cystic Fibrosis of the Pancreas: The Role of CFTR Channel in the Regulation of Intracellular Ca 2+ Signaling and Mitochondrial Function in the Exocrine Pancreas. Front Physiol 2018; 9:1585. [PMID: 30618777 PMCID: PMC6306458 DOI: 10.3389/fphys.2018.01585] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 10/23/2018] [Indexed: 12/26/2022] Open
Abstract
Cystic fibrosis (CF) is the most common genetic disorder that causes a significant damage in secretory epithelial cells due to the defective ion flux across the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel. Pancreas is one of the organs most frequently damaged by the disease leading to pancreatic insufficiency, abdominal pain and an increased risk of acute pancreatitis in CF patients causing a significant decrease in the quality of life. CFTR plays a central role in the pancreatic ductal secretory functions by carrying Cl- and HCO3 - ions across the apical membrane. Therefore pathophysiological studies in CF mostly focused on the effects of impaired ion secretion by pancreatic ductal epithelial cells leading to exocrine pancreatic damage. However, several studies indicated that CFTR has a central role in the regulation of intracellular signaling processes and is now more widely considered as a signaling hub in epithelial cells. In contrast, elevated intracellular Ca2+ level was observed in the lack of functional CFTR in different cell types including airway epithelial cells. In addition, impaired CFTR expression has been correlated with damaged mitochondrial function in epithelial cells. These alterations of intracellular signaling in CF are not well characterized in the exocrine pancreas yet. Therefore in this review we would like to summarize the complex role of CFTR in the exocrine pancreas with a special focus on the intracellular signaling and mitochondrial function.
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Affiliation(s)
- Tamara Madácsy
- First Department of Medicine, University of Szeged, Szeged, Hungary.,HAS-USZ Momentum Epithel Cell Signalling and Secretion Research Group, Szeged, Hungary
| | - Petra Pallagi
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Jozsef Maleth
- First Department of Medicine, University of Szeged, Szeged, Hungary.,HAS-USZ Momentum Epithel Cell Signalling and Secretion Research Group, Szeged, Hungary.,Department of Public Health, University of Szeged, Szeged, Hungary
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19
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Ahmadi S, Xia S, Wu YS, Di Paola M, Kissoon R, Luk C, Lin F, Du K, Rommens J, Bear CE. SLC6A14, an amino acid transporter, modifies the primary CF defect in fluid secretion. eLife 2018; 7:37963. [PMID: 30004386 PMCID: PMC6054531 DOI: 10.7554/elife.37963] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 07/12/2018] [Indexed: 01/29/2023] Open
Abstract
The severity of intestinal disease associated with Cystic Fibrosis (CF) is variable in the patient population and this variability is partially conferred by the influence of modifier genes. Genome-wide association studies have identified SLC6A14, an electrogenic amino acid transporter, as a genetic modifier of CF-associated meconium ileus. The purpose of the current work was to determine the biological role of Slc6a14, by disrupting its expression in CF mice bearing the major mutation, F508del. We found that disruption of Slc6a14 worsened the intestinal fluid secretion defect, characteristic of these mice. In vitro studies of mouse intestinal organoids revealed that exacerbation of the primary defect was associated with reduced arginine uptake across the apical membrane, with aberrant nitric oxide and cyclic GMP-mediated regulation of the major CF-causing mutant protein. Together, these studies highlight the role of this apical transporter in modifying cellular nitric oxide levels, residual function of the major CF mutant and potentially, its promise as a therapeutic target.
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Affiliation(s)
- Saumel Ahmadi
- Department of Physiology, University of Toronto, Toronto, Canada.,Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, Canada
| | - Sunny Xia
- Department of Physiology, University of Toronto, Toronto, Canada.,Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, Canada
| | - Yu-Sheng Wu
- Department of Physiology, University of Toronto, Toronto, Canada.,Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, Canada
| | - Michelle Di Paola
- Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, Canada.,Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Randolph Kissoon
- Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, Canada
| | - Catherine Luk
- Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, Canada
| | - Fan Lin
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Kai Du
- Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, Canada
| | - Johanna Rommens
- Department of Molecular Genetics, University of Toronto, Toronto, Canada.,Programme in Genetics and Genome Biology, Research Institute, Hospital for Sick Children, Toronto, Canada
| | - Christine E Bear
- Department of Physiology, University of Toronto, Toronto, Canada.,Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, Canada.,Department of Biochemistry, University of Toronto, Toronto, Canada
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20
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Yin J, Tse CM, Avula LR, Singh V, Foulke-Abel J, de Jonge HR, Donowitz M. Molecular Basis and Differentiation-Associated Alterations of Anion Secretion in Human Duodenal Enteroid Monolayers. Cell Mol Gastroenterol Hepatol 2018; 5:591-609. [PMID: 29930980 PMCID: PMC6009799 DOI: 10.1016/j.jcmgh.2018.02.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 02/05/2018] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS Human enteroids present a novel tool to study human intestinal ion transport physiology and pathophysiology. The present study describes the contributions of Cl- and HCO3- secretion to total cyclic adenosine monophosphate (cAMP)-stimulated electrogenic anion secretion in human duodenal enteroid monolayers and the relevant changes after differentiation. METHODS Human duodenal enteroids derived from 4 donors were grown as monolayers and differentiated by a protocol that includes the removal of Wnt3A, R-spondin1, and SB202190 for 5 days. The messenger RNA level and protein expression of selected ion transporters and carbonic anhydrase isoforms were determined by quantitative real-time polymerase chain reaction and immunoblotting, respectively. Undifferentiated and differentiated enteroid monolayers were mounted in the Ussing chamber/voltage-current clamp apparatus, using solutions that contained as well as lacked Cl- and HCO3-/CO2, to determine the magnitude of forskolin-induced short-circuit current change and its sensitivity to specific inhibitors that target selected ion transporters and carbonic anhydrase(s). RESULTS Differentiation resulted in a significant reduction in the messenger RNA level and protein expression of cystic fibrosis transmembrane conductance regulator, (CFTR) Na+/K+/2Cl- co-transporter 1 (NKCC1), and potassium channel, voltage gated, subfamily E, regulatory subunit 3 (KCNE3); and, conversely, increase of down-regulated-in-adenoma (DRA), electrogenic Na+/HCO3- co-transporter 1 (NBCe1), carbonic anhydrase 2 (CA2), and carbonic anhydrase 4 (CA4). Both undifferentiated and differentiated enteroids showed active cAMP-stimulated anion secretion that included both Cl- and HCO3- secretion as the magnitude of total active anion secretion was reduced after the removal of extracellular Cl- or HCO3-/CO2. The magnitude of total anion secretion in differentiated enteroids was approximately 33% of that in undifferentiated enteroids, primarily owing to the reduction in Cl- secretion with no significant change in HCO3- secretion. Anion secretion was consistently lower but detectable in differentiated enteroids compared with undifferentiated enteroids in the absence of extracellular Cl- or HCO3-/CO2. Inhibiting CFTR, NKCC1, carbonic anhydrase(s), cAMP-activated K+ channel(s), and Na+/K+-adenosine triphosphatase reduced cAMP-stimulated anion secretion in both undifferentiated and differentiated enteroids. CONCLUSIONS Human enteroids recapitulate anion secretion physiology of small intestinal epithelium. Enteroid differentiation is associated with significant alterations in the expression of several ion transporters and carbonic anhydrase isoforms, leading to a reduced but preserved anion secretory phenotype owing to markedly reduced Cl- secretion but no significant change in HCO3- secretion.
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Key Words
- AE2, anion exchanger 2
- Bicarbonate Secretion
- CA, carbonic anhydrase
- CFTR, cystic fibrosis transmembrane conductance regulator
- Chloride Secretion
- DRA
- DRA, down-regulated-in-adenoma
- Ion Transport
- Isc, short-circuit current
- KRB, Krebs–Ringer bicarbonate
- NBC, Na+/HCO3- co-transporter
- NBCe1, electrogenic Na+/HCO3- co-transporter 1
- NHE, Na+/H+ exchanger
- NKCC1, Na+/K+/2Cl- co-transporter 1
- SDS, sodium dodecyl sulfate
- SITS, 4-Acetamido-4′-isothiocyanato-2,2′-stilbenedisulfonic acid disodium salt hydrate
- TER, transepithelial electrical resistance
- cAMP, cyclic adenosine monophosphate
- mRNA, messenger ribonucleic acid
- qRT-PCR, quantitative real-time polymerase chain reaction
- ΔIsc, change in short-circuit current
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Affiliation(s)
- Jianyi Yin
- Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Chung-Ming Tse
- Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Leela Rani Avula
- Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Varsha Singh
- Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Jennifer Foulke-Abel
- Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Hugo R. de Jonge
- Department of Gastroenterology and Hepatology, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Mark Donowitz
- Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, Maryland,Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland,Correspondence Address correspondence to: Mark Donowitz, MD, Johns Hopkins University School of Medicine, 720 Rutland Avenue, 925 Ross Research Building, Baltimore, Maryland 21205. fax: (410) 955-9677.
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21
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Jin H, Wen G, Deng S, Wan S, Xu J, Liu X, Xie R, Dong H, Tuo B. Oestrogen upregulates the expression levels and functional activities of duodenal mucosal CFTR and SLC26A6. Exp Physiol 2017; 101:1371-1382. [PMID: 27615377 DOI: 10.1113/ep085803] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Accepted: 09/01/2016] [Indexed: 12/29/2022]
Abstract
NEW FINDINGS What is the central question of this study? Duodenal ulcer is a common disease. A sex-based difference in the incidence of duodenal ulcer has long been observed clinically, but the cause is unclear. What is the main finding and its importance? Duodenal mucosal bicarbonate secretion is the most important protective factor in duodenal mucosa against acid-induced damage. The cystic fibrosis transmembrane conductance regulator (CFTR) and the solute-linked carrier 26 gene family A6 (SLC26A6) are two key bicarbonate transport proteins that mediate duodenal mucosal bicarbonate secretion. We demonstrate that endogenous oestrogen upregulates the expression levels and functional activities of duodenal mucosal CFTR and SLC26A6, which contributes to the sex difference in the prevalence of duodenal ulcer. The incidence of duodenal ulcer is markedly lower in women than men, but the cause of the sex difference is not clear. The cystic fibrosis transmembrane conductance regulator (CFTR) and the solute-linked carrier 26 gene family A6 (SLC26A6) are two key bicarbonate transport proteins that mediate duodenal mucosal bicarbonate secretion, which is an important protective factor against acid-induced duodenal injury. The aim of this study was to investigate the effect of oestrogen on the expressions and functional activities of CFTR and SLC26A6 in duodenal mucosa. We found that the expression levels of duodenal CFTR and SLC26A6 were markedly higher in young (20- to 30-year-old) women than in young men and old (60- to 70-year-old) women and men. The expression levels of CFTR and SLC26A6 in young women were markedly higher in preovulatory phases than in premenstrual phases, which was consistent with the changes of serum estradiol concentrations. Further results showed that duodenal CFTR and SLC26A6 expression levels in female mice were markedly decreased after ovariectomy, and supplementation with estradiol reversed the changes in CFTR and SLC26A6. 17β-Estradiol increased CFTR and SLC26A6 expression levels of human duodenocytes in experiments in vitro. Functional experiments showed that basal and forskolin- and prostaglandin E2 -stimulated duodenal bicarbonate secretion in ovariectomized mice was markedly decreased and, likewise, supplementation with 17β-estradiol reversed the changes. In conclusion, endogenous oestrogen upregulates the expressions and functional activities of CFTR and SLC26A6 in duodenal mucosa, which could contribute to protection of the duodenum and explain the sex difference in the prevalence of duodenal ulcer.
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Affiliation(s)
- Hai Jin
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China.,Research Center of Medicine and Biology, Zunyi Medical College, Zunyi, China
| | - Guorong Wen
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China.,Research Center of Medicine and Biology, Zunyi Medical College, Zunyi, China
| | - Shili Deng
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China
| | - Shuo Wan
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China
| | - Jingyu Xu
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China.,Research Center of Medicine and Biology, Zunyi Medical College, Zunyi, China
| | - Xuemei Liu
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China
| | - Rui Xie
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China
| | - Hui Dong
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China.,Research Center of Medicine and Biology, Zunyi Medical College, Zunyi, China
| | - Biguang Tuo
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China. .,Digestive Disease Institute of Guizhou Province, Zunyi, China. .,Research Center of Medicine and Biology, Zunyi Medical College, Zunyi, China.
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22
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Yang X, Wen G, Tuo B, Zhang F, Wan H, He J, Yang S, Dong H. Molecular mechanisms of calcium signaling in the modulation of small intestinal ion transports and bicarbonate secretion. Oncotarget 2017; 9:3727-3740. [PMID: 29423078 PMCID: PMC5790495 DOI: 10.18632/oncotarget.23197] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 12/01/2017] [Indexed: 01/13/2023] Open
Abstract
Background and Purpose: Although Ca2+ signaling may stimulate small intestinal ion secretion, little is known about its critical role and the molecular mechanisms of Ca2+-mediated biological action. Key Results Activation of muscarinic receptors by carbachol(CCh) stimulated mouse duodenal Isc, which was significantly inhibited in Ca2+-free serosal solution and by several selective store-operated Ca2+ channels(SOC) blockers added to the serosal side of duodenal tissues. Furthermore, we found that CRAC/Orai channels may represent the molecular candidate of SOC in intestinal epithelium. CCh increased intracellular Ca2+ but not cAMP, and Ca2+ signaling mediated duodenal Cl- and HCO3- secretion in wild type mice but not in CFTR knockout mice. CCh induced duodenal ion secretion and stimulated PI3K/Akt activity in duodenal epithelium, all of which were inhibited by selective PI3K inhibitors with different structures. CCh-induced Ca2+ signaling also stimulated the phosphorylation of CFTR proteins and their trafficking to the plasma membrane of duodenal epithelial cells, which were inhibited again by selective PI3K inhibitors. Materials and Methods Functional, biochemical and morphological experiments were performed to examine ion secretion, PI3K/Akt and CFTR activity of mouse duodenal epithelium. Ca2+ imaging was performed on HT-29 cells. Conclusions and Implications Ca2+ signaling plays a critical role in intestinal ion secretion via CRAC/Orai-mediated SOCE mechanism on the serosal side of epithelium. We also demonstrated the molecular mechanisms of Ca2+ signaling in CFTR-mediated secretion via novel PI3K/Akt pathway. Our findings suggest new perspectives for drug targets to protect the upper GI tract and control liquid homeostasis in the small intestine.
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Affiliation(s)
- Xin Yang
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Guorong Wen
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, and Digestive Disease Institute of Guizhou Province, Zunyi 563003, China
| | - Biguang Tuo
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, and Digestive Disease Institute of Guizhou Province, Zunyi 563003, China
| | - Fenglian Zhang
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Hanxing Wan
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Jialin He
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Shiming Yang
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, and Digestive Disease Institute of Guizhou Province, Zunyi 563003, China
| | - Hui Dong
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.,Department of Medicine, School of Medicine, University of California, San Diego, CA 92093, USA
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23
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He J, Yang X, Guo Y, Zhang F, Wan H, Sun X, Tuo B, Dong H. Ca 2+ signaling in HCO 3- secretion and protection of upper GI tract. Oncotarget 2017; 8:102681-102689. [PMID: 29254280 PMCID: PMC5731990 DOI: 10.18632/oncotarget.21840] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2017] [Accepted: 09/23/2017] [Indexed: 01/05/2023] Open
Abstract
The cytosolic calcium ([Ca2+]cyt) is one of the most important cell signaling that can modulate gastrointestinal (GI) epithelial secretion and promote GI mucosal wound repair. The GI mucosal bicarbonate secretion is the main mechanism of mucosal protection. Our research team has been working in this field and provided solid evidence for the important role of Ca2+ signaling in the regulation of GI epithelial secretion and the underlying molecular mechanisms. In this review, we attempt to systemically review the current status of our knowledge on the role of Ca2+ signaling in the regulation of intestinal bicarbonate secretion and in the upper GI epithelial protection. We expect that novel targets could be identified for drug development to better protect GI mucosa and treat mucosal injury with the advance in this filed.
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Affiliation(s)
- Jialin He
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China
| | - Xin Yang
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Yanjun Guo
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Fenglian Zhang
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Hanxing Wan
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Xuemei Sun
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Biguang Tuo
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China
| | - Hui Dong
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China.,Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
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24
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Benedetto R, Ousingsawat J, Wanitchakool P, Zhang Y, Holtzman MJ, Amaral M, Rock JR, Schreiber R, Kunzelmann K. Epithelial Chloride Transport by CFTR Requires TMEM16A. Sci Rep 2017; 7:12397. [PMID: 28963502 PMCID: PMC5622110 DOI: 10.1038/s41598-017-10910-0] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 08/16/2017] [Indexed: 12/15/2022] Open
Abstract
Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is the secretory chloride/bicarbonate channel in airways and intestine that is activated through ATP binding and phosphorylation by protein kinase A, but fails to operate in cystic fibrosis (CF). TMEM16A (also known as anoctamin 1, ANO1) is thought to function as the Ca2+ activated secretory chloride channel independent of CFTR. Here we report that tissue specific knockout of the TMEM16A gene in mouse intestine and airways not only eliminates Ca2+-activated Cl− currents, but unexpectedly also abrogates CFTR-mediated Cl− secretion and completely abolishes cAMP-activated whole cell currents. The data demonstrate fundamentally new roles of TMEM16A in differentiated epithelial cells: TMEM16A provides a mechanism for enhanced ER Ca2+ store release, possibly engaging Store Operated cAMP Signaling (SOcAMPS) and activating Ca2+ regulated adenylyl cyclases. TMEM16A is shown to be essential for proper activation and membrane expression of CFTR. This intimate regulatory relationship is the cause for the functional overlap of CFTR and Ca2+-dependent chloride transport.
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Affiliation(s)
- Roberta Benedetto
- Physiological institute, University of Regensburg, University street 31, D-93053, Regensburg, Germany
| | - Jiraporn Ousingsawat
- Physiological institute, University of Regensburg, University street 31, D-93053, Regensburg, Germany
| | - Podchanart Wanitchakool
- Physiological institute, University of Regensburg, University street 31, D-93053, Regensburg, Germany
| | - Yong Zhang
- Department of Medicine and Department of Cell Biology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Michael J Holtzman
- Department of Medicine and Department of Cell Biology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Margarida Amaral
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8, 1749-016, Lisboa, Portugal
| | - Jason R Rock
- Department of Anatomy, University of California, San Francisco, USA
| | - Rainer Schreiber
- Physiological institute, University of Regensburg, University street 31, D-93053, Regensburg, Germany
| | - Karl Kunzelmann
- Physiological institute, University of Regensburg, University street 31, D-93053, Regensburg, Germany.
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25
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Bicarbonate in cystic fibrosis. J Cyst Fibros 2017; 16:653-662. [PMID: 28732801 DOI: 10.1016/j.jcf.2017.06.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 06/22/2017] [Accepted: 06/22/2017] [Indexed: 11/20/2022]
Abstract
BACKGROUND Cystic fibrosis (CF, mucoviscidosis) is caused by mutations in the gene encoding CF transmembrane conductance regulator (CFTR), which is a chloride and bicarbonate channel necessary for fluid secretion and extracellular alkalization. For a long time, research concentrated on abnormal Cl- and Na+ transport, but neglected bicarbonate as a crucial factor in CF. METHODS The present short review reports early findings as well as recent insights into the role of CFTR for bicarbonate transport and its defects in CF. RESULTS The available data indicate impaired bicarbonate transport not only in pancreas, intestine, airways, and reproductive organs, but also in salivary glands, sweat duct and renal tubular epithelial cells. Defective bicarbonate transport is closely related to the impaired mucus properties and mucus blocking in secretory organs of CF patients, causing the life threatening lung disease. CONCLUSIONS Apart from the devastating lung disease, abrogated bicarbonate transport also leads to many other organ dysfunctions, which are outlined in the present review.
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26
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The role of intestinal oxalate transport in hyperoxaluria and the formation of kidney stones in animals and man. Urolithiasis 2016; 45:89-108. [PMID: 27913853 DOI: 10.1007/s00240-016-0952-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 11/22/2016] [Indexed: 12/26/2022]
Abstract
The intestine exerts a considerable influence over urinary oxalate in two ways, through the absorption of dietary oxalate and by serving as an adaptive extra-renal pathway for elimination of this waste metabolite. Knowledge of the mechanisms responsible for oxalate absorption and secretion by the intestine therefore have significant implications for understanding the etiology of hyperoxaluria, as well as offering potential targets for future treatment strategies for calcium oxalate kidney stone disease. In this review, we present the recent developments and advances in this area over the past 10 years, and put to the test some of the new ideas that have emerged during this time, using human and mouse models. A key focus for our discussion are the membrane-bound anion exchangers, belonging to the SLC26 gene family, some of which have been shown to participate in transcellular oxalate absorption and secretion. This has offered the opportunity to not only examine the roles of these specific transporters, revealing their importance to oxalate homeostasis, but to also probe the relative contributions made by the active transcellular and passive paracellular components of oxalate transport across the intestine. We also discuss some of the various physiological stimuli and signaling pathways which have been suggested to participate in the adaptation and regulation of intestinal oxalate transport. Finally, we offer an update on research into Oxalobacter formigenes, alongside recent investigations of other oxalate-degrading gut bacteria, in both laboratory animals and humans.
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27
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Wen G, Jin H, Deng S, Xu J, Liu X, Xie R, Tuo B. Effects of Helicobacter pylori Infection on the Expressions and Functional Activities of Human Duodenal Mucosal Bicarbonate Transport Proteins. Helicobacter 2016; 21:536-547. [PMID: 27004488 DOI: 10.1111/hel.12309] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND The mechanisms for Helicobacter pylori (H. pylori)-induced duodenal ulcerogenesis are not fully understood. In this study, we investigated the effects of H. pylori infection on the expressions and functional activities of human duodenal mucosal bicarbonate transport proteins and hope to further clarify the pathogenesis of H. pylori-associated duodenal ulcer. MATERIALS AND METHODS The experiments were performed in the patients with H. pylori-associated duodenal ulcers, H. pylori-associated chronic gastritis, and H. pylori-negative healthy subjects. Duodenal mucosal bicarbonate secretion was measured by Ussing Chamber technology. RESULTS The expressions of duodenal mucosal bicarbonate transport proteins, CFTR (cystic fibrosis transmembrane conductance regulator) and SLC26A6 (solute-linked carrier 26 gene A6), in the patients with H. pylori-associated duodenal ulcers were markedly lower than those in healthy controls. Basal and both forskolin- and prostaglandin E2 -stimulated duodenal mucosal bicarbonate secretions in the patients with H. pylori-associated duodenal ulcers were also lower than those in healthy controls. After anti-H. pylori treatment for H. pylori-associated duodenal ulcers, duodenal mucosal bicarbonate secretion and CFTR and SLC26A6 expressions in H. pylori-eradicated patients recovered to levels comparable to healthy controls, but those were found to be not significantly altered in non-H. pylori-eradicated patients. The further results showed that decreases in the H. pylori-induced CFTR and SLC26A6 expression were related to the severity and virulent factors of H. pylori infection. CONCLUSION H. pylori infection impairs the expressions and functional activities of duodenal mucosal bicarbonate transport proteins, CFTR and SLC26A6, which contributes to the development of duodenal ulcer.
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Affiliation(s)
- Guorong Wen
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China.,Research Center of Medicine and Biology, Zunyi Medical College, Zunyi, China
| | - Hai Jin
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China.,Research Center of Medicine and Biology, Zunyi Medical College, Zunyi, China
| | - Shili Deng
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China
| | - Jingyu Xu
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China.,Research Center of Medicine and Biology, Zunyi Medical College, Zunyi, China
| | - Xuemei Liu
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China
| | - Rui Xie
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China
| | - Biguang Tuo
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China.,Research Center of Medicine and Biology, Zunyi Medical College, Zunyi, China
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28
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High-fat diet modifies the PPAR-γ pathway leading to disruption of microbial and physiological ecosystem in murine small intestine. Proc Natl Acad Sci U S A 2016; 113:E5934-E5943. [PMID: 27638207 DOI: 10.1073/pnas.1612559113] [Citation(s) in RCA: 163] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Diet is among the most important factors contributing to intestinal homeostasis, and basic functions performed by the small intestine need to be tightly preserved to maintain health. Little is known about the direct impact of high-fat (HF) diet on small-intestinal mucosal defenses and spatial distribution of the microbiota during the early phase of its administration. We observed that only 30 d after HF diet initiation, the intervillous zone of the ileum-which is usually described as free of bacteria-became occupied by a dense microbiota. In addition to affecting its spatial distribution, HF diet also drastically affected microbiota composition with a profile characterized by the expansion of Firmicutes (appearance of Erysipelotrichi), Proteobacteria (Desulfovibrionales) and Verrucomicrobia, and decrease of Bacteroidetes (family S24-7) and Candidatus arthromitus A decrease in antimicrobial peptide expression was predominantly observed in the ileum where bacterial density appeared highest. In addition, HF diet increased intestinal permeability and decreased cystic fibrosis transmembrane conductance regulator (Cftr) and the Na-K-2Cl cotransporter 1 (Nkcc1) gene and protein expressions, leading to a decrease in ileal secretion of chloride, likely responsible for massive alteration in mucus phenotype. This complex phenotype triggered by HF diet at the interface between the microbiota and the mucosal surface was reversed when the diet was switched back to standard composition or when mice were treated for 1 wk with rosiglitazone, a specific agonist of peroxisome proliferator-activated receptor-γ (PPAR-γ). Moreover, weaker expression of antimicrobial peptide-encoding genes and intervillous bacterial colonization were observed in Ppar-γ-deficient mice, highlighting the major role of lipids in modulation of mucosal immune defenses.
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29
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Abstract
cGMP controls many cellular functions ranging from growth, viability, and differentiation to contractility, secretion, and ion transport. The mammalian genome encodes seven transmembrane guanylyl cyclases (GCs), GC-A to GC-G, which mainly modulate submembrane cGMP microdomains. These GCs share a unique topology comprising an extracellular domain, a short transmembrane region, and an intracellular COOH-terminal catalytic (cGMP synthesizing) region. GC-A mediates the endocrine effects of atrial and B-type natriuretic peptides regulating arterial blood pressure/volume and energy balance. GC-B is activated by C-type natriuretic peptide, stimulating endochondral ossification in autocrine way. GC-C mediates the paracrine effects of guanylins on intestinal ion transport and epithelial turnover. GC-E and GC-F are expressed in photoreceptor cells of the retina, and their activation by intracellular Ca(2+)-regulated proteins is essential for vision. Finally, in the rodent system two olfactorial GCs, GC-D and GC-G, are activated by low concentrations of CO2and by peptidergic (guanylins) and nonpeptidergic odorants as well as by coolness, which has implications for social behaviors. In the past years advances in human and mouse genetics as well as the development of sensitive biosensors monitoring the spatiotemporal dynamics of cGMP in living cells have provided novel relevant information about this receptor family. This increased our understanding of the mechanisms of signal transduction, regulation, and (dys)function of the membrane GCs, clarified their relevance for genetic and acquired diseases and, importantly, has revealed novel targets for therapies. The present review aims to illustrate these different features of membrane GCs and the main open questions in this field.
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Affiliation(s)
- Michaela Kuhn
- Institute of Physiology, University of Würzburg, Würzburg, Germany
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30
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Ruhr IM, Mager EM, Takei Y, Grosell M. The differential role of renoguanylin in osmoregulation and apical Cl−/HCO3− exchange activity in the posterior intestine of the Gulf toadfish (Opsanus beta). Am J Physiol Regul Integr Comp Physiol 2015; 309:R399-409. [DOI: 10.1152/ajpregu.00118.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 05/20/2015] [Indexed: 11/22/2022]
Abstract
The guanylin family of peptides are effective regulators of intestinal physiology in marine teleosts. In the distal intestinal segments, they inhibit or reverse fluid absorption by inhibiting the absorptive short-circuit current ( Isc). The present findings demonstrate that mRNA from guanylin and uroguanylin, as well as at least one isoform of the guanylin peptide receptor, apical guanylyl cyclase-C (GC-C), was highly expressed in the intestine and rectum of the Gulf toadfish ( Opsanus beta). In the posterior intestine, GC-C, as well as the cystic fibrosis transmembrane conductance regulator and basolateral Na+/K+/2Cl− cotransporter, which comprise a Cl−-secretory pathway, were transcriptionally upregulated in 60 parts per thousand (ppt). The present study also shows that, in intestinal tissues from Gulf toadfish held in 35 ppt, renoguanylin (RGN) expectedly causes net Cl− secretion, inhibits both the absorptive Isc and fluid absorption, and decreases HCO3− secretion. Likewise, in intestinal tissues from Gulf toadfish acclimated to 60 ppt, RGN also inhibits the absorptive Isc and fluid absorption but to an even greater extent, corresponding with the mRNA expression data. In contrast, RGN does not alter Cl− flux and, instead, elevates HCO3− secretion in the 60-ppt group, suggesting increased apical Cl−/HCO3− exchange activity by SLC26a6. Overall, these findings reinforce the hypotheses that the guanylin peptide system is important for salinity acclimatization and that the secretory response could facilitate the removal of solids, such as CaCO3 precipitates, from the intestine.
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Affiliation(s)
- Ilan M. Ruhr
- Department of Marine Biology and Ecology, The Rosenstiel School of Marine and Atmospheric Science, The University of Miami, Miami, Florida
| | - Edward M. Mager
- Department of Marine Biology and Ecology, The Rosenstiel School of Marine and Atmospheric Science, The University of Miami, Miami, Florida
| | - Yoshio Takei
- Department of Marine Bioscience, The Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba, Japan
| | - Martin Grosell
- Department of Marine Biology and Ecology, The Rosenstiel School of Marine and Atmospheric Science, The University of Miami, Miami, Florida
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31
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Tchernychev B, Ge P, Kessler MM, Solinga RM, Wachtel D, Tobin JV, Thomas SR, Lunte CE, Fretzen A, Hannig G, Bryant AP, Kurtz CB, Currie MG, Silos-Santiago I. MRP4 Modulation of the Guanylate Cyclase-C/cGMP Pathway: Effects on Linaclotide-Induced Electrolyte Secretion and cGMP Efflux. J Pharmacol Exp Ther 2015. [PMID: 26216942 DOI: 10.1124/jpet.115.224329] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
MRP4 mediates the efflux of cGMP and cAMP and acts as an important regulator of these secondary messengers, thereby affecting signaling events mediated by cGMP and cAMP. Immunofluorescence staining showed high MRP4 expression localized predominantly in the apical membrane of rat colonic epithelium. In vitro studies were performed using a rat colonic mucosal layer mounted in an Ussing chamber. Linaclotide activation of the guanylate cyclase-C (GC-C)/cGMP pathway induced a concentration-dependent increase in transepithelial ion current [short-circuit current (Isc)] across rat colonic mucosa (EC50: 9.2 nM). Pretreatment of colonic mucosa with the specific MRP4 inhibitor MK571 potentiated linaclotide-induced electrolyte secretion and augmented linaclotide-stimulated intracellular cGMP accumulation. Notably, pretreatment with the phosphodiesterase 5 inhibitor sildenafil increased basal Isc, but had no amplifying effect on linaclotide-induced Isc. MRP4 inhibition selectively affected the activation phase, but not the deactivation phase, of linaclotide. In contrast, incubation with a GC-C/Fc chimera binding to linaclotide abrogated linaclotide-induced Isc, returning to baseline. Furthermore, linaclotide activation of GC-C induced cGMP secretion from the apical and basolateral membranes of colonic epithelium. MRP4 inhibition blocked cGMP efflux from the apical membrane, but not the basolateral membrane. These data reveal a novel, previously unrecognized mechanism that functionally couples GC-C-induced luminal electrolyte transport and cGMP secretion to spatially restricted, compartmentalized regulation by MRP4 at the apical membrane of intestinal epithelium. These findings have important implications for gastrointestinal disorders with symptoms associated with dysregulated fluid homeostasis, such as irritable bowel syndrome with constipation, chronic idiopathic constipation, and secretory diarrhea.
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Affiliation(s)
- Boris Tchernychev
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Pei Ge
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Marco M Kessler
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Robert M Solinga
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Derek Wachtel
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Jenny V Tobin
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Sara R Thomas
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Craig E Lunte
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Angelika Fretzen
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Gerhard Hannig
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Alexander P Bryant
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Caroline B Kurtz
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Mark G Currie
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
| | - Inmaculada Silos-Santiago
- Ironwood Pharmaceuticals, Cambridge, Massachusetts (B.T., P.G., M.M.K., R.M.S., D.W., J.V.T., A.F., G.H., A.P.B., C.B.K., M.G.C., I.S.-S.); and Ralph N. Adams Institute for Bioanalytical Chemistry, Department of Chemistry, University of Kansas, Lawrence, Kansas (S.R.T., C.E.L.)
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Tang L, Peng M, Liu L, Chang W, Binder HJ, Cheng SX. Calcium-sensing receptor stimulates Cl(-)- and SCFA-dependent but inhibits cAMP-dependent HCO3(-) secretion in colon. Am J Physiol Gastrointest Liver Physiol 2015; 308:G874-83. [PMID: 25792563 PMCID: PMC4437021 DOI: 10.1152/ajpgi.00341.2014] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 03/10/2015] [Indexed: 02/07/2023]
Abstract
Colonic bicarbonate (HCO3(-)) secretion is a well-established physiological process that is closely linked to overall fluid and electrolyte movement in the mammalian colon. These present studies show that extracellular calcium-sensing receptor (CaSR), a fundamental mechanism for sensing and regulating ionic and nutrient compositions of extracellular milieu in the small and large intestine, regulates HCO3(-) secretion. Basal and induced HCO3(-) secretory responses to CaSR agonists were determined by pH stat techniques used in conjunction with short-circuit current measurements in mucosa from rat distal colon mounted in Ussing chambers. R568, a specific CaSR activator, stimulated lumen Cl(-)- and short-chain fatty acid (SCFA)-dependent HCO3(-) secretion but inhibited cyclic nucleotide-activated HCO3(-) secretion. Consequently, at physiological conditions (either at basal or during lumen acid challenge) when electroneutral Cl(-)/HCO3(-) and SCFA/HCO3(-) exchangers dominate, CaSR stimulates HCO3(-) secretion; in contrast, in experimental conditions that stimulate fluid and HCO3(-) secretion, e.g., when forskolin activates electrogenic cystic fibrosis transmembrane conductance regulator-mediated HCO3(-) conductance, CaSR activation inhibits HCO3(-) secretion. Corresponding changes in JHCO3 (μeq·h(-1)·cm(-2), absence vs. presence of R568) were 0.18 ± 0.03 vs. 0.31 ± 0.08 under basal nonstimulated conditions and 1.85 ± 0.23 vs. 0.45 ± 0.06 under forskolin-stimulated conditions. Similarly, activation of CaSR by R568 stimulated Cl(-)- and SCFA-dependent HCO3(-) secretion and inhibited cAMP-dependent HCO3(-) secretion in colon mucosa of wild-type mice; such effects were abolished in CaSR-null mice. These results suggest a new paradigm for regulation of intestinal ion transport in which HCO3(-) secretion may be fine-tuned by CaSR in accordance with nutrient availability and state of digestion and absorption. The ability of CaSR agonists to inhibit secretagogue-induced intestinal HCO3(-) secretion suggests that modulation of CaSR activity may provide a new therapeutic approach to correct HCO3(-) deficit and metabolic acidosis, a primary cause of morbidity and mortality in acute infectious diarrheal illnesses.
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Affiliation(s)
- Lieqi Tang
- 1Division of Gastroenterology, Nutrition and Hepatology, Department of Pediatrics, University of Florida, Gainesville, Florida;
| | - Minzhi Peng
- 1Division of Gastroenterology, Nutrition and Hepatology, Department of Pediatrics, University of Florida, Gainesville, Florida;
| | - Li Liu
- 2Department of Pediatrics, Guangzhou Women and Children's Medical Center, Guangzhou, Guangdong, People's Republic of China;
| | - Wenhan Chang
- 3Endocrine Research, VA Medical Center, University of California at San Francisco, San Francisco, California;
| | - Henry J. Binder
- 4Department of Internal Medicine, Yale University, New Haven, Connecticut
| | - Sam X. Cheng
- 1Division of Gastroenterology, Nutrition and Hepatology, Department of Pediatrics, University of Florida, Gainesville, Florida;
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Ruhr IM, Bodinier C, Mager EM, Esbaugh AJ, Williams C, Takei Y, Grosell M. Guanylin peptides regulate electrolyte and fluid transport in the Gulf toadfish (Opsanus beta) posterior intestine. Am J Physiol Regul Integr Comp Physiol 2014; 307:R1167-79. [DOI: 10.1152/ajpregu.00188.2014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The physiological effects of guanylin (GN) and uroguanylin (UGN) on fluid and electrolyte transport in the teleost fish intestine have yet to be thoroughly investigated. In the present study, the effects of GN, UGN, and renoguanylin (RGN; a GN and UGN homolog) on short-circuit current ( Isc) and the transport of Cl−, Na+, bicarbonate (HCO3−), and fluid in the Gulf toadfish ( Opsanus beta) intestine were determined using Ussing chambers, pH-stat titration, and intestinal sac experiments. GN, UGN, and RGN reversed the Isc of the posterior intestine (absorptive-to-secretory), but not of the anterior intestine. RGN decreased baseline HCO3− secretion, but increased Cl− and fluid secretion in the posterior intestine. The secretory response of the posterior intestine coincides with the presence of basolateral NKCC1 and apical cystic fibrosis transmembrane conductance regulator (CFTR), the latter of which is lacking in the anterior intestine and is not permeable to HCO3− in the posterior intestine. However, the response to RGN by the posterior intestine is counterintuitive given the known role of the marine teleost intestine as a salt- and water-absorbing organ. These data demonstrate that marine teleosts possess a tissue-specific secretory response, apparently associated with seawater adaptation, the exact role of which remains to be determined.
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Affiliation(s)
- Ilan M. Ruhr
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida; and
| | - Charlotte Bodinier
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida; and
| | - Edward M. Mager
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida; and
| | - Andrew J. Esbaugh
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida; and
| | - Cameron Williams
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida; and
| | - Yoshio Takei
- Ocean Research Institute, University of Tokyo, Tokyo, Japan
| | - Martin Grosell
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida; and
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Xie R, Dong X, Wong C, Vallon V, Tang B, Sun J, Yang S, Dong H. Molecular mechanisms of calcium-sensing receptor-mediated calcium signaling in the modulation of epithelial ion transport and bicarbonate secretion. J Biol Chem 2014; 289:34642-53. [PMID: 25331955 DOI: 10.1074/jbc.m114.592774] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Epithelial ion transport is mainly under the control of intracellular cAMP and Ca(2+) signaling. Although the molecular mechanisms of cAMP-induced epithelial ion secretion are well defined, those induced by Ca(2+) signaling remain poorly understood. Because calcium-sensing receptor (CaSR) activation results in an increase in cytosolic Ca(2+) ([Ca(2+)]cyt) but a decrease in cAMP levels, it is a suitable receptor for elucidating the mechanisms of [Ca(2+)]cyt-mediated epithelial ion transport and duodenal bicarbonate secretion (DBS). CaSR proteins have been detected in mouse duodenal mucosae and human intestinal epithelial cells. Spermine and Gd(3+), two CaSR activators, markedly stimulated DBS without altering duodenal short circuit currents in wild-type mice but did not affect DBS and duodenal short circuit currents in cystic fibrosis transmembrane conductance regulator (CFTR) knockout mice. Clotrimazole, a selective blocker of intermediate conductance Ca(2+)-activated K(+) channels but not chromanol 293B, a selective blocker of cAMP-activated K(+) channels (KCNQ1), significantly inhibited CaSR activator-induced DBS, which was similar in wild-type and KCNQ1 knockout mice. HCO3 (-) fluxes across epithelial cells were activated by a CFTR activator, but blocked by a CFTR inhibitor. CaSR activators induced HCO3 (-) fluxes, which were inhibited by a receptor-operated channel (ROC) blocker. Moreover, CaSR activators dose-dependently raised cellular [Ca(2+)]cyt, which was abolished in Ca(2+)-free solutions and inhibited markedly by selective CaSR antagonist calhex 231, and ROC blocker in both animal and human intestinal epithelial cells. Taken together, CaSR activation triggers Ca(2+)-dependent DBS, likely through the ROC, intermediate conductance Ca(2+)-activated K(+) channels, and CFTR channels. This study not only reveals that [Ca(2+)]cyt signaling is critical to modulate DBS but also provides novel insights into the molecular mechanisms of CaSR-mediated Ca(2+)-induced DBS.
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Affiliation(s)
- Rui Xie
- From the Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China, the Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi 563003, China, and
| | - Xiao Dong
- the Department of Medicine, University of California, San Diego, La Jolla, California 92093
| | - Chase Wong
- the Department of Medicine, University of California, San Diego, La Jolla, California 92093
| | - Volker Vallon
- the Department of Medicine, University of California, San Diego, La Jolla, California 92093, the Veterans Affairs San Diego Healthcare System, La Jolla, California 92161
| | - Bo Tang
- From the Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Jun Sun
- the Departments of Biochemistry, Internal Medicine (GI), and Microbiology/Immunology, Rush University, Chicago, Illinois 60612
| | - Shiming Yang
- From the Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China,
| | - Hui Dong
- From the Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China, the Department of Medicine, University of California, San Diego, La Jolla, California 92093,
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Chemical rescue of ΔF508-CFTR in C127 epithelial cells reverses aberrant extracellular pH acidification to wild-type alkalization as monitored by microphysiometry. Biochem Biophys Res Commun 2014; 451:535-40. [DOI: 10.1016/j.bbrc.2014.08.036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 08/04/2014] [Indexed: 11/19/2022]
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Sommansson A, Wan Saudi WS, Nylander O, Sjöblom M. The ethanol-induced stimulation of rat duodenal mucosal bicarbonate secretion in vivo is critically dependent on luminal Cl-. PLoS One 2014; 9:e102654. [PMID: 25033198 PMCID: PMC4102535 DOI: 10.1371/journal.pone.0102654] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 06/22/2014] [Indexed: 12/31/2022] Open
Abstract
Alcohol may induce metabolic and functional changes in gastrointestinal epithelial cells, contributing to impaired mucosal barrier function. Duodenal mucosal bicarbonate secretion (DBS) is a primary epithelial defense against gastric acid and also has an important function in maintaining the homeostasis of the juxtamucosal microenvironment. The aim in this study was to investigate the effects of the luminal perfusion of moderate concentrations of ethanol in vivo on epithelial DBS, fluid secretion and paracellular permeability. Under thiobarbiturate anesthesia, a ∼30-mm segment of the proximal duodenum with an intact blood supply was perfused in situ in rats. The effects on DBS, duodenal transepithelial net fluid flux and the blood-to-lumen clearance of 51Cr-EDTA were investigated. Perfusing the duodenum with isotonic solutions of 10% or 15% ethanol-by-volume for 30 min increased DBS in a concentration-dependent manner, while the net fluid flux did not change. Pre-treatment with the CFTR inhibitor CFTRinh172 (i.p. or i.v.) did not change the secretory response to ethanol, while removing Cl− from the luminal perfusate abolished the ethanol-induced increase in DBS. The administration of hexamethonium (i.v.) but not capsazepine significantly reduced the basal net fluid flux and the ethanol-induced increase in DBS. Perfusing the duodenum with a combination of 1.0 mM HCl and 15% ethanol induced significantly greater increases in DBS than 15% ethanol or 1.0 mM HCl alone but did not influence fluid flux. Our data demonstrate that ethanol induces increases in DBS through a mechanism that is critically dependent on luminal Cl− and partly dependent on enteric neural pathways involving nicotinic receptors. Ethanol and HCl appears to stimulate DBS via the activation of different bicarbonate transporting mechanisms.
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Affiliation(s)
- Anna Sommansson
- Division of Gastrointestinal Physiology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Wan Salman Wan Saudi
- Division of Gastrointestinal Physiology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Olof Nylander
- Division of Gastrointestinal Physiology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Markus Sjöblom
- Division of Gastrointestinal Physiology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
- * E-mail:
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da Silva Lima V, Crajoinas RO, Carraro-Lacroix LR, Godinho AN, Dias JLG, Dariolli R, Girardi ACC, Fonteles MC, Malnic G, Lessa LMA. Uroguanylin inhibits H-ATPase activity and surface expression in renal distal tubules by a PKG-dependent pathway. Am J Physiol Cell Physiol 2014; 307:C532-41. [PMID: 25031022 DOI: 10.1152/ajpcell.00392.2013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Cumulative evidence suggests that guanylin peptides play an important role on electrolyte homeostasis. We have previously reported that uroguanylin (UGN) inhibits bicarbonate reabsorption in a renal distal tubule. In the present study, we tested the hypothesis that the bicarbonaturic effect of UGN is at least in part attributable to inhibition of H(+)-ATPase-mediated hydrogen secretion in the distal nephron. By in vivo stationary microperfusion experiments, we were able to show that UGN inhibits H(+)-ATPase activity by a PKG-dependent pathway because KT5823 (PKG inhibitor) abolished the UGN effect on distal bicarbonate reabsorption and H89 (PKA inhibitor) was unable to prevent it. The in vivo results were confirmed by the in vitro experiments, where we used fluorescence microscopy to measure intracellular pH (pHi) recovery after an acid pulse with NH4Cl. By this technique, we observed that UGN and 8 bromoguanosine-cGMP (8Br-cGMP) inhibited H(+)-ATPase-dependent pHi recovery and that the UGN inhibitory effect was abolished in the presence of the PKG inhibitor. In addition, by using RT-PCR technique, we verified that Madin-Darby canine kidney (MDCK)-C11 cells express guanylate cyclase-C. Besides, UGN stimulated an increase of both cGMP content and PKG activity but was unable to increase the production of cellular cAMP content and PKA activity. Furthermore, we found that UGN reduced cell surface abundance of H+-ATPase B1 subunit in MDCK-C11 and that this effect was abolished by the PKG inhibitor. Taken together, our data suggest that UGN inhibits H(+)-ATPase activity and surface expression in renal distal cells by a cGMP/PKG-dependent pathway.
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Affiliation(s)
- Vanessa da Silva Lima
- Superior Institute of Biomedical Sciences, State University of Ceará, Fortaleza, Ceará, Brazil
| | | | - Luciene R Carraro-Lacroix
- Department of Physiology and Biophysics, Biomedical Sciences Institute, University of São Paulo, São Paulo, São Paulo, Brazil
| | - Alana N Godinho
- Superior Institute of Biomedical Sciences, State University of Ceará, Fortaleza, Ceará, Brazil
| | - João L G Dias
- Superior Institute of Biomedical Sciences, State University of Ceará, Fortaleza, Ceará, Brazil
| | | | | | - Manassés C Fonteles
- Superior Institute of Biomedical Sciences, State University of Ceará, Fortaleza, Ceará, Brazil; Mackenzie University, São Paulo, São Paulo, Brazil
| | - Gerhard Malnic
- Department of Physiology and Biophysics, Biomedical Sciences Institute, University of São Paulo, São Paulo, São Paulo, Brazil
| | - Lucília M A Lessa
- Superior Institute of Biomedical Sciences, State University of Ceará, Fortaleza, Ceará, Brazil;
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Anoctamins support calcium-dependent chloride secretion by facilitating calcium signaling in adult mouse intestine. Pflugers Arch 2014; 467:1203-13. [PMID: 24974903 DOI: 10.1007/s00424-014-1559-2] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 06/12/2014] [Accepted: 06/17/2014] [Indexed: 12/13/2022]
Abstract
Intestinal epithelial electrolyte secretion is activated by increase in intracellular cAMP or Ca(2+) and opening of apical Cl(-) channels. In infants and young animals, but not in adults, Ca(2+)-activated chloride channels may cause secretory diarrhea during rotavirus infection. While detailed knowledge exists concerning the contribution of cAMP-activated cystic fibrosis transmembrane conductance regulator (CFTR) channels, analysis of the role of Ca(2+)-dependent Cl(-) channels became possible through identification of the anoctamin (TMEM16) family of proteins. We demonstrate expression of several anoctamin paralogues in mouse small and large intestines. Using intestinal-specific mouse knockout models for anoctamin 1 (Ano1) and anoctamin 10 (Ano10) and a conventional knockout model for anoctamin 6 (Ano6), we demonstrate the role of anoctamins for Ca(2+)-dependent Cl(-) secretion induced by the muscarinic agonist carbachol (CCH). Ano1 is preferentially expressed in the ileum and large intestine, where it supports Ca(2+)-activated Cl(-) secretion. In contrast, Ano10 is essential for Ca(2+)-dependent Cl(-) secretion in jejunum, where expression of Ano1 was not detected. Although broadly expressed, Ano6 has no role in intestinal cholinergic Cl(-) secretion. Ano1 is located in a basolateral compartment/membrane rather than in the apical membrane, where it supports CCH-induced Ca(2+) increase, while the essential and possibly only apical Cl(-) channel is CFTR. These results define a new role of Ano1 for intestinal Ca(2+)-dependent Cl(-) secretion and demonstrate for the first time a contribution of Ano10 to intestinal transport.
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Liu X, Li T, Riederer B, Lenzen H, Ludolph L, Yeruva S, Tuo B, Soleimani M, Seidler U. Loss of Slc26a9 anion transporter alters intestinal electrolyte and HCO3(-) transport and reduces survival in CFTR-deficient mice. Pflugers Arch 2014; 467:1261-75. [PMID: 24965066 PMCID: PMC4434866 DOI: 10.1007/s00424-014-1543-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 05/19/2014] [Accepted: 05/20/2014] [Indexed: 12/16/2022]
Abstract
Slc26a9 is an anion transporter that is strongly expressed in the stomach and lung. Slc26a9 variants were recently found associated with a higher incidence of meconium ileus in cystic fibrosis (CF) infants, raising the question whether Slc26a9 is expressed in the intestine and what its functional role is. Slc26a9 messenger RNA (mRNA) was found highly expressed in the mucosae of the murine and human upper gastrointestinal tract, with an abrupt decrease in expression levels beyond the duodenum. Absence of SLC26a9 expression strongly increased the intestinally related mortality in cystic fibrosis transmembrane conductance regulator (CFTR)-deficient mice. Proximal duodenal JHCO3(-) and fluid secretion were reduced in the absence of Slc26a9 expression. In the proximal duodenum of young Slc26a9 KO mice, the glands and villi/crypts were elongated and proliferation was enhanced. This difference was lost with ageing, as were the alterations in fluid movement, whereas the reduction in JHCO3(-) remained. Laser dissection followed by qPCR suggested Slc26a9 expression to be crypt-predominant in the duodenum. In summary, deletion of Slc26a9 caused bicarbonate secretory and fluid absorptive changes in the proximal duodenal mucosa and increased the postweaning death rates in CFTR-deficient mice. Functional alterations in the duodenum were most prominent at young ages. We assume that the association of meconium ileus and Slc26a9 variants may be related to maldigestion and impaired downstream signaling caused by loss of upper GI tract digestive functions, aggravating the situation of lack of secretion and sticky mucus at the site of obstruction in CF intestine.
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Affiliation(s)
- Xuemei Liu
- Department of Gastroenterology, Hannover Medical School, Hannover, Germany
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Song P, Du Y, Song W, Liu X, Hong L, Li H, Xie H, Zhou L, Tuo B, Zheng S. Bile deficiency induces changes in intestinal Cl(-) and HCO3 (-) secretions in mice. Acta Physiol (Oxf) 2014; 211:421-33. [PMID: 24731192 DOI: 10.1111/apha.12301] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 08/28/2013] [Accepted: 04/10/2014] [Indexed: 12/14/2022]
Abstract
AIMS Biliary tract obstruction is a common clinical lesion. However, the effect of biliary tract obstruction on intestinal secretion is poorly understood. In this study, we made an investigation on intestinal HCO3 (-) and Cl(-) secretions in an experimental model of murine biliary duct ligation. METHODS Murine intestinal mucosal HCO3 (-) and Cl(-) secretions were examined in vitro in Ussing chambers by pH-stat and short-circuit current (Isc ) techniques. The mRNA and protein expressions of the cystic fibrosis transmembrane conductance regulator (CFTR) and the Na(+) -K(+) -2Cl(-) cotransporter (NKCC1) were analysed by real-time PCR, western blot and immunohistochemistry. RESULTS Basal Cl(-) secretion and forskolin-stimulated duodenal and jejunal mucosal HCO3 (-) and Cl(-) secretions in mice with common biliary duct ligation were markedly elevated, compared with controls (P < 0.05 and P < 0.01). Further experiments showed that basal Cl(-) secretion and forskolin-stimulated duodenal and jejunal mucosal HCO3 (-) and Cl(-) secretions in mice with external bile drainage were also markedly elevated. CFTRinh -172 inhibited forskolin-stimulated HCO3 (-) and Cl(-) secretions. The mRNA and protein expression levels of CFTR and NKCC1 in the intestinal mucosa with both biliary duct ligation and external bile drainage were markedly higher than those in controls (P < 0.001). Bile acid administration restored the changes in function and expression of CFTR and NKCC1 in the intestinal mucosa. CONCLUSION Bile deficiency in the intestine up-regulates the expressions of intestinal mucosal CFTR and NKCC1 and enhances intestinal mucosal HCO3 (-) and Cl(-) secretion capacity, which contributes to the understanding of intestinal physiological function for patients with biliary duct obstruction.
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Affiliation(s)
- P. Song
- Key Laboratory of Combined Multi-organ Transplantation; Ministry of Public Health; First Affiliated Hospital; School of Medicine; Zhejiang University; Hangzhou 310003 China
| | - Y. Du
- Key Laboratory of Combined Multi-organ Transplantation; Ministry of Public Health; First Affiliated Hospital; School of Medicine; Zhejiang University; Hangzhou 310003 China
| | - W. Song
- Key Laboratory of Combined Multi-organ Transplantation; Ministry of Public Health; First Affiliated Hospital; School of Medicine; Zhejiang University; Hangzhou 310003 China
| | - X. Liu
- Department of Surgery; First Affiliated Hospital; School of Medicine; Zhejiang University; Hangzhou 310003 China
| | - L. Hong
- Key Laboratory of Combined Multi-organ Transplantation; Ministry of Public Health; First Affiliated Hospital; School of Medicine; Zhejiang University; Hangzhou 310003 China
| | - H. Li
- Key Laboratory of Combined Multi-organ Transplantation; Ministry of Public Health; First Affiliated Hospital; School of Medicine; Zhejiang University; Hangzhou 310003 China
| | - H. Xie
- Key Laboratory of Combined Multi-organ Transplantation; Ministry of Public Health; First Affiliated Hospital; School of Medicine; Zhejiang University; Hangzhou 310003 China
| | - L. Zhou
- Key Laboratory of Combined Multi-organ Transplantation; Ministry of Public Health; First Affiliated Hospital; School of Medicine; Zhejiang University; Hangzhou 310003 China
| | - B. Tuo
- Department of Gastroenterology; Affiliated Hospital of Zunyi Medical College; Zunyi 563003 China
| | - S. Zheng
- Key Laboratory of Combined Multi-organ Transplantation; Ministry of Public Health; First Affiliated Hospital; School of Medicine; Zhejiang University; Hangzhou 310003 China
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Billet A, Hanrahan JW. The secret life of CFTR as a calcium-activated chloride channel. J Physiol 2013; 591:5273-8. [PMID: 23959675 PMCID: PMC3936366 DOI: 10.1113/jphysiol.2013.261909] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 08/15/2013] [Indexed: 12/27/2022] Open
Abstract
cAMP-stimulated anion conductance is defective in cystic fibrosis (CF). The regulatory domain of CFTR, the anion channel protein encoded by the CF gene, possesses an unusually high density of consensus sequences for phosphorylation by protein kinase A (14 in a stretch of <200 amino acids). Thus it is not surprising that CFTR is viewed primarily as a cAMP-stimulated anion channel, and most studies have focused on this mode of activation. However, there is growing evidence that CFTR also responds to Ca(2+)-mobilizing secretagogues and contributes substantially to cholinergic and purinergic responses in native tissues. G protein-coupled receptors that signal through Gαq can stimulate CFTR channels by activating Ca(2+)-dependent adenylyl cyclase and tyrosine kinases, and also by inhibiting protein phosphatase type 2A. Here we review evidence for these novel mechanisms of CFTR activation and discuss how they may help explain previous observations.
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Affiliation(s)
- Arnaud Billet
- J. W. Hanrahan: Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal, QC, Canada H3G 1Y6.
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Gastrointestinal HCO3- transport and epithelial protection in the gut: new techniques, transport pathways and regulatory pathways. Curr Opin Pharmacol 2013; 13:900-8. [PMID: 24280619 DOI: 10.1016/j.coph.2013.10.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 09/29/2013] [Accepted: 10/01/2013] [Indexed: 02/07/2023]
Abstract
The concept of a protective alkaline gastric and duodenal mucus layer is a century old, yet it is amazing how much new information on HCO3(-) transport pathways has emerged recently, made possible by the extensive utilization of gene-deleted and transgenic mice and novel techniques to study HCO3(-) transport. This review highlights recent findings regarding the importance of HCO3(-) for mucosal protection of duodenum and other gastrointestinal epithelia against luminal acid and other damaging factors. Recently, methods have been developed to visualize HCO3(-) transport in vivo by assessing the surface pH in the mucus layer, as well as the epithelial pH. New information about HCO3(-) transport pathways, and emerging concepts about the intricate regulatory network that governs duodenal HCO3(-) secretion are described, and new perspectives for drug therapy discussed.
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Jakab RL, Collaco AM, Ameen NA. Characterization of CFTR High Expresser cells in the intestine. Am J Physiol Gastrointest Liver Physiol 2013; 305:G453-65. [PMID: 23868408 PMCID: PMC3761243 DOI: 10.1152/ajpgi.00094.2013] [Citation(s) in RCA: 26] [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 CFTR High Expresser (CHE) cells express eightfold higher levels of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel compared with neighboring enterocytes and were first identified by our laboratory (Ameen et al., Gastroenterology 108: 1016, 1995). We used double-label immunofluorescence microscopy to further study these enigmatic epithelial cells in rat intestine in vivo or ex vivo. CHE cells were found in duodenum, most frequent in proximal jejunum, and absent in ileum and colon. CFTR abundance increased in CHE cells along the crypt-villus axis. The basolateral Na(+)K(+)Cl(-) cotransporter NKCC1, a key transporter involved in Cl(-) secretion, was detected at similar levels in CHE cells and neighboring enterocytes at steady state. Microvilli appeared shorter in CHE cells, with low levels of Myosin 1a, a villus enterocyte-specific motor that retains sucrase/isomaltase in the brush-border membrane (BBM). CHE cells lacked alkaline phosphatase and absorptive villus enterocyte BBM proteins, including Na(+)H(+) exchanger NHE3, Cl(-)/HCO3(-) exchanger SLC26A6 (putative anion exchanger 1), and sucrase/isomaltase. High levels of the vacuolar-ATPase proton pump were observed in the apical domain of CHE cells. Levels of the NHE regulatory factor NHERF1, Na-K-ATPase, and Syntaxin 3 were similar to that of neighboring enterocytes. cAMP or acetylcholine stimulation robustly increased apical CFTR and basolateral NKCC1 disproportionately in CHE cells relative to neighboring enterocytes. These data strongly argue for a specialized role of CHE cells in Cl(-)-mediated "high-volume" fluid secretion on the villi of the proximal small intestine.
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Affiliation(s)
- Robert L. Jakab
- Departments of 1Pediatrics/Gastroenterology and Hepatology, and
| | - Anne M. Collaco
- Departments of 1Pediatrics/Gastroenterology and Hepatology, and
| | - Nadia A. Ameen
- Departments of 1Pediatrics/Gastroenterology and Hepatology, and ,2Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut
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Mann EA, Harmel-Laws E, Cohen MB, Steinbrecher KA. Guanylate cyclase C limits systemic dissemination of a murine enteric pathogen. BMC Gastroenterol 2013; 13:135. [PMID: 24004613 PMCID: PMC3766218 DOI: 10.1186/1471-230x-13-135] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 08/21/2013] [Indexed: 02/07/2023] Open
Abstract
Background Guanylate Cyclase C (GC-C) is an apically-oriented transmembrane receptor that is expressed on epithelial cells of the intestine. Activation of GC-C by the endogenous ligands guanylin or uroguanylin elevates intracellular cGMP and is implicated in intestinal ion secretion, cell proliferation, apoptosis, intestinal barrier function, as well as the susceptibility of the intestine to inflammation. Our aim was to determine if GC-C is required for host defense during infection by the murine enteric pathogen Citrobacter rodentium of the family Enterobacteriacea. Methods GC-C+/+ control mice or those having GC-C genetically ablated (GC-C−/−) were administered C. rodentium by orogastric gavage and analyzed at multiple time points up to post-infection day 20. Commensal bacteria were characterized in uninfected GC-C+/+ and GC-C−/− mice using 16S rRNA PCR analysis. Results GC-C−/− mice had an increase in C. rodentium bacterial load in stool relative to GC-C+/+. C. rodentium infection strongly decreased guanylin expression in GC-C+/+ mice and, to an even greater degree, in GC-C−/− animals. Fluorescent tracer studies indicated that mice lacking GC-C, unlike GC-C+/+ animals, had a substantial loss of intestinal barrier function early in the course of infection. Epithelial cell apoptosis was significantly increased in GC-C−/− mice following 10 days of infection and this was associated with increased frequency and numbers of C. rodentium translocation out of the intestine. Infection led to significant liver histopathology in GC-C−/− mice as well as lymphocyte infiltration and elevated cytokine and chemokine expression. Relative to naïve GC-C+/+ mice, the commensal microflora load in uninfected GC-C−/− mice was decreased and bacterial composition was imbalanced and included outgrowth of the Enterobacteriacea family. Conclusions This work demonstrates the novel finding that GC-C signaling is an essential component of host defense during murine enteric infection by reducing bacterial load and preventing systemic dissemination of attaching/effacing-lesion forming bacterial pathogens such as C. rodentium.
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Affiliation(s)
- Elizabeth A Mann
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
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Collaco AM, Jakab RL, Hoekstra NE, Mitchell KA, Brooks A, Ameen NA. Regulated traffic of anion transporters in mammalian Brunner's glands: a role for water and fluid transport. Am J Physiol Gastrointest Liver Physiol 2013; 305:G258-75. [PMID: 23744739 PMCID: PMC3742856 DOI: 10.1152/ajpgi.00485.2012] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The Brunner's glands of the proximal duodenum exert barrier functions through secretion of glycoproteins and antimicrobial peptides. However, ion transporter localization, function, and regulation in the glands are less clear. Mapping the subcellular distribution of transporters is an important step toward elucidating trafficking mechanisms of fluid transport in the gland. The present study examined 1) changes in the distribution of intestinal anion transporters and the aquaporin 5 (AQP5) water channel in rat Brunner's glands following second messenger activation and 2) anion transporter distribution in Brunner's glands from healthy and disease-affected human tissues. Cystic fibrosis transmembrane conductance regulator (CFTR), AQP5, sodium-potassium-coupled chloride cotransporter 1 (NKCC1), sodium-bicarbonate cotransporter (NBCe1), and the proton pump vacuolar ATPase (V-ATPase) were localized to distinct membrane domains and in endosomes at steady state. Carbachol and cAMP redistributed CFTR to the apical membrane. cAMP-dependent recruitment of CFTR to the apical membrane was accompanied by recruitment of AQP5 that was reversed by a PKA inhibitor. cAMP also induced apical trafficking of V-ATPase and redistribution of NKCC1 and NBCe1 to the basolateral membranes. The steady-state distribution of AQP5, CFTR, NBCe1, NKCC1, and V-ATPase in human Brunner's glands from healthy controls, cystic fibrosis, and celiac disease resembled that of rat; however, the distribution profiles were markedly attenuated in the disease-affected duodenum. These data support functional transport of chloride, bicarbonate, water, and protons by second messenger-regulated traffic in mammalian Brunner's glands under physiological and pathophysiological conditions.
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Affiliation(s)
- Anne M. Collaco
- 1Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut;
| | - Robert L. Jakab
- 1Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut;
| | - Nadia E. Hoekstra
- 1Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut;
| | - Kisha A. Mitchell
- 2Department of Pathology, Yale University School of Medicine, New Haven, Connecticut; and
| | - Amos Brooks
- 2Department of Pathology, Yale University School of Medicine, New Haven, Connecticut; and
| | - Nadia A. Ameen
- 1Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut; ,3Department Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut
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Yang N, Garcia MAS, Quinton PM. Normal mucus formation requires cAMP-dependent HCO3- secretion and Ca2+-mediated mucin exocytosis. J Physiol 2013; 591:4581-93. [PMID: 23818690 DOI: 10.1113/jphysiol.2013.257436] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Evidence from the pathology in cystic fibrosis (CF) and recent results in vitro indicate that HCO3- is required for gel-forming mucins to form the mucus that protects epithelial surfaces. Mucus formation and release is a complex process that begins with an initial intracellular phase of synthesis, packaging and apical granule exocytosis that is followed by an extracellular phase of mucin swelling, transport and discharge into a lumen. Exactly where HCO3- becomes crucial in these processes is unknown, but we observed that in the presence of HCO3-, stimulating dissected segments of native mouse intestine with 5-hydroxytryptamine (5-HT) and prostaglandin E2 (PGE2) induced goblet cell exocytosis followed by normal mucin discharge in wild-type (WT) intestines. CF intestines that inherently lack cystic fibrosis transmembrane conductance regulator (CFTR)-dependent HCO3- secretion also demonstrated apparently normal goblet cell exocytosis, but in contrast, this was not followed by similar mucin discharge. Moreover, we found that even in the presence of HCO3-, when WT intestines were stimulated only with a Ca2+-mediated agonist (carbachol), exocytosis was followed by poor discharge as with CF intestines. However, when the Ca2+-mediated agonist was combined with a cAMP-mediated agonist (isoproterenol (isoprenaline) or vasoactive intestinal peptide) in the presence of HCO3- both normal exocytosis and normal discharge was observed. These results indicate that normal mucus formation requires concurrent activation of a Ca2+-mediated exocytosis of mucin granules and an independent cAMP-mediated, CFTR-dependent, HCO3- secretion that appears to mainly enhance the extracellular phases of mucus excretion.
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Affiliation(s)
- Ning Yang
- N. Yang: Division of Respiratory Medicine, Department of Pediatrics, University of California School of Medicine, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0830, USA.
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Song P, Song W, Liu X, Jin C, Xie H, Zhou L, Tuo B, Zheng S. Function and expression of cystic fibrosis transmembrane conductance regulator after small intestinal transplantation in mice. PLoS One 2013; 8:e62536. [PMID: 23626828 PMCID: PMC3633864 DOI: 10.1371/journal.pone.0062536] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 03/22/2013] [Indexed: 01/14/2023] Open
Abstract
The secretion function of intestinal graft is one of the most important factors for successful intestinal transplantation. Cystic fibrosis transmembrane conductance regulator (CFTR) mediates HCO3- and Cl- secretions in intestinal epithelial cells. In this study, we made investigation on the expression and function of CFTR in an experimental model of murine small intestinal transplantation. Heterotopic intestinal transplantations were performed in syngeneic mice. The mRNA and protein expressions of CFTR were analyzed by real time PCR and western blot. Murine intestinal mucosal HCO3- and Cl- secretions were examined in vitro in Ussing chambers by the pH stat and short circuit current (Isc) techniques. The results showed that forskolin, an activator of CFTR, stimulated jejunal mucosal epithelial HCO3- and Cl- secretions in mice, but forskolin-stimulated HCO3- and Cl- secretions in donor and recipient jejunal mucosae of mice after heterotopic jejunal transplantation were markedly decreased, compared with controls (P<0.001). The mRNA and protein expression levels of CFTR in donor and recipient jejunal mucosae of mice were also markedly lower than those in controls (P<0.001), and the mRNA and protein expression levels of tumor necrosis factor α (TNFα) were markedly increased in donor jejunal mucosae of mice (P<0.001), compared with controls. Further experiments showed that TNFα down-regulated the expression of CFTR mRNA in murine jejunal mucosa. In conclusion, after intestinal transplantation, the function of CFTR was impaired, and its mRNA and protein expressions were down-regulated, which may be induced by TNFα.
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Affiliation(s)
- Penghong Song
- Key Laboratory of Combined Multi-organ Transplantation of Ministry of Public Health, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Wenfeng Song
- Key Laboratory of Combined Multi-organ Transplantation of Ministry of Public Health, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Xiaosun Liu
- Department of Surgery, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Changhai Jin
- Key Laboratory of Combined Multi-organ Transplantation of Ministry of Public Health, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Haiyang Xie
- Key Laboratory of Combined Multi-organ Transplantation of Ministry of Public Health, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Lin Zhou
- Key Laboratory of Combined Multi-organ Transplantation of Ministry of Public Health, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Biguang Tuo
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical College, Zunyi, China
| | - Shusen Zheng
- Key Laboratory of Combined Multi-organ Transplantation of Ministry of Public Health, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
- * E-mail:
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48
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Singh AK, Xia W, Riederer B, Juric M, Li J, Zheng W, Cinar A, Xiao F, Bachmann O, Song P, Praetorius J, Aalkjaer C, Seidler U. Essential role of the electroneutral Na+-HCO3- cotransporter NBCn1 in murine duodenal acid-base balance and colonic mucus layer build-up in vivo. J Physiol 2013; 591:2189-204. [PMID: 23401617 DOI: 10.1113/jphysiol.2012.247874] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Duodenal epithelial cells need efficient defence strategies during gastric acidification of the lumen, while colonic mucosa counteracts damage by pathogens by building up a bacteria-free adherent mucus layer. Transport of HCO3(-) is considered crucial for duodenal defence against acid as well as for mucus release and expansion, but the transport pathways involved are incompletely understood. This study investigated the significance of the electroneutral Na(+)-HCO3(-) cotransporter NBCn1 for duodenal defence against acid and colonic mucus release. NBCn1 was localized to the basolateral membrane of duodenal villous enterocytes and of colonic crypt cells, with predominant expression in goblet cells. Duodenal villous enterocyte intracellular pH was studied before and during a luminal acid load by two-photon microscopy in exteriorized, vascularly perfused, indicator (SNARF-1 AM)-loaded duodenum of isoflurane-anaesthetized, systemic acid-base-controlled mice. Acid-induced HCO3(-) secretion was measured in vivo by single-pass perfusion and pH-stat titration. After a luminal acid load, NBCn1-deficient duodenocytes were unable to recover rapidly from intracellular acidification and could not respond adequately with protective HCO3(-) secretion. In the colon, build-up of the mucus layer was delayed, and a decreased thickness of the adherent mucus layer was observed, suggesting that basolateral HCO3(-) uptake is essential for optimal release of mucus. The electroneutral Na(+)-HCO3(-) cotransporter NBCn1 displays a differential cellular distribution in the murine intestine and is essential for HCO3(-)-dependent mucosal protective functions, such as recovery of intracellular pH and HCO3(-) secretion in the duodenum and secretion of mucus in the colon.
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Affiliation(s)
- Anurag Kumar Singh
- Department of Gastroenterology, Hannover Medical School, Hannover, Germany
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Cooper JL, Quinton PM, Ballard ST. Mucociliary transport in porcine trachea: differential effects of inhibiting chloride and bicarbonate secretion. Am J Physiol Lung Cell Mol Physiol 2012. [PMID: 23204069 DOI: 10.1152/ajplung.00143.2012] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
This study was designed to assess the relative importance of Cl(-) and HCO(3)(-) secretion to mucociliary transport rate (MCT) in ex vivo porcine tracheas. MCT was measured in one group of tissues that was exposed to adventitial HCO(3)(-)-free solution while a parallel group was exposed to adventitial HCO(3)(-)-replete solution. After measurement of baseline MCT rates, acetylcholine (ACh) was added to stimulate submucosal gland mucous liquid secretion, and MCT rates were again measured. Before ACh addition, the mean MCT was higher in the HCO(3)(-)-free group (4.2 ± 0.9 mm/min) than in the HCO(3)(-)-replete group (2.3 ± 0.3 mm/min), but this difference was not statistically significant. ACh addition significantly increased MCT in both groups, but ACh-stimulated MCT was significantly lower in the HCO(3)(-)-free group (11.0 ± 1.5 mm/min) than in the HCO(3)(-)-replete group (17.0 ± 2.0 mm/min). A second series of experiments examined the effect on MCT of blocking Cl(-) secretion with 100 μM bumetanide. Before adding ACh, MCT in the bumetanide-treated group (1.0 ± 0.2 mm/min) was significantly lower than in the control group (3.8 ± 1.1 mm/min). ACh addition significantly increased MCT in both groups, but there was no significant difference between the bumetanide-treated group (21.4 ± 1.7 mm/min) and control group (19.5 ± 3.4 mm/min). These results indicate that ACh-stimulated MCT has greater dependence on HCO(3)(-) secretion, whereas the basal MCT rate has greater dependence on Cl(-) secretion.
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Affiliation(s)
- Jeffrey L Cooper
- Department of Physiology, College of Medicine, University of South Alabama, Mobile, AL 36688, USA
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Jakab RL, Collaco AM, Ameen NA. Cell-specific effects of luminal acid, bicarbonate, cAMP, and carbachol on transporter trafficking in the intestine. Am J Physiol Gastrointest Liver Physiol 2012; 303:G937-50. [PMID: 22936272 PMCID: PMC3469693 DOI: 10.1152/ajpgi.00452.2011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Changes in intestinal luminal pH affect mucosal ion transport. The aim of this study was to compare how luminal pH and specific second messengers modulate the membrane traffic of four major ion transporters (CFTR, NHE3, NKCC1, and NBCe1) in rat small intestine. Ligated duodenal, jejunal, and ileal segments were infused with acidic or alkaline saline, 8-Br-cAMP, or the calcium agonist carbachol in vivo for 20 min. Compared with untreated intestine, lumen pH was reduced after cAMP or carbachol and increased following HCO(3)(-)-saline. Following HCl-saline, lumen pH was restored to control pH levels. All four secretory stimuli resulted in brush-border membrane (BBM) recruitment of CFTR in crypts and villi. In villus enterocytes, CFTR recruitment was coincident with internalization of BBM NHE3 and basolateral membrane recruitment of the bicarbonate transporter NBCe1. Both cAMP and carbachol recruited NKCC1 to the basolateral membrane of enterocytes, while luminal acid or HCO(3)(-) retained NKCC1 in intracellular vesicles. Luminal acid resulted in robust recruitment of CFTR and NBCe1 to their respective enterocyte membrane domains in the upper third of the villi; luminal HCO(3)(-) induced similar membrane changes lower in the villi. These findings indicate that each stimulus promotes a specific transporter trafficking response along the crypt-villus axis. This is the first demonstration that physiologically relevant secretory stimuli exert their actions in villus enterocytes by membrane recruitment of CFTR and NBCe1 in tandem with NHE3 internalization.
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Affiliation(s)
- Robert L. Jakab
- 1Departments of Pediatrics/Gastroenterology and Hepatology, and
| | - Anne M. Collaco
- 1Departments of Pediatrics/Gastroenterology and Hepatology, and
| | - Nadia A. Ameen
- 1Departments of Pediatrics/Gastroenterology and Hepatology, and ,2Cellular and Molecular Physiology Yale University School of Medicine, New Haven, Connecticut
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