1
|
Wu Z, Liu H, Wang X. Advancements in understanding bacterial enteritis pathogenesis through organoids. Mol Biol Rep 2024; 51:512. [PMID: 38622483 DOI: 10.1007/s11033-024-09495-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
Bacterial enteritis has a substantial role in contributing to a large portion of the global disease burden and serves as a major cause of newborn mortality. Despite advancements gained from current animal and cell models in improving our understanding of pathogens, their widespread application is hindered by apparent drawbacks. Therefore, more precise models are imperatively required to develop more accurate studies on host-pathogen interactions and drug discovery. Since the emergence of intestinal organoids, massive studies utilizing organoids have been conducted to study the pathogenesis of bacterial enteritis, revealing new mechanisms and validating established ones. In this review, we focus on the advancements of several bacterial pathogenesis mechanisms observed in intestinal organoid/enteroid models, exploring the host response and bacterial effectors during the infection process. Finally, we address the features that warrant additional investigation or could be enhanced in existing organoid models in order to guide future research endeavors.
Collapse
Affiliation(s)
- Zhengyang Wu
- Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Hongyuan Liu
- Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Xianli Wang
- Shanghai Jiao Tong University School of Public Health, Shanghai, 200025, China.
| |
Collapse
|
2
|
Zachos NC, Vaughan H, Sarker R, Est-Witte S, Chakraborty M, Baetz NW, Yu H, Yarov-Yarovoy V, McNamara G, Green JJ, Tse CM, Donowitz M. A Novel Peptide Prevents Enterotoxin- and Inflammation-Induced Intestinal Fluid Secretion by Stimulating Sodium-Hydrogen Exchanger 3 Activity. Gastroenterology 2023; 165:986-998.e11. [PMID: 37429363 PMCID: PMC11283679 DOI: 10.1053/j.gastro.2023.06.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 06/05/2023] [Accepted: 06/09/2023] [Indexed: 07/12/2023]
Abstract
BACKGROUND & AIMS Acute diarrheal diseases are the second most common cause of infant mortality in developing countries. This is contributed to by lack of effective drug therapy that shortens the duration or lessens the volume of diarrhea. The epithelial brush border sodium (Na+)/hydrogen (H+) exchanger 3 (NHE3) accounts for a major component of intestinal Na+ absorption and is inhibited in most diarrheas. Because increased intestinal Na+ absorption can rehydrate patients with diarrhea, NHE3 has been suggested as a potential druggable target for drug therapy for diarrhea. METHODS A peptide (sodium-hydrogen exchanger 3 stimulatory peptide [N3SP]) was synthesized to mimic the part of the NHE3 C-terminus that forms a multiprotein complex that inhibits NHE3 activity. The effect of N3SP on NHE3 activity was evaluated in NHE3-transfected fibroblasts null for other plasma membrane NHEs, a human colon cancer cell line that models intestinal absorptive enterocytes (Caco-2/BBe), human enteroids, and mouse intestine in vitro and in vivo. N3SP was delivered into cells via a hydrophobic fluorescent maleimide or nanoparticles. RESULTS N3SP uptake stimulated NHE3 activity at nmol/L concentrations under basal conditions and partially reversed the reduced NHE3 activity caused by elevated adenosine 3',5'-cyclic monophosphate, guanosine 3',5'-cyclic monophosphate, and Ca2+ in cell lines and in in vitro mouse intestine. N3SP also stimulated intestinal fluid absorption in the mouse small intestine in vivo and prevented cholera toxin-, Escherichia coli heat-stable enterotoxin-, and cluster of differentiation 3 inflammation-induced fluid secretion in a live mouse intestinal loop model. CONCLUSIONS These findings suggest pharmacologic stimulation of NHE3 activity as an efficacious approach for the treatment of moderate/severe diarrheal diseases.
Collapse
Affiliation(s)
- Nicholas C Zachos
- Division of Gastroenterology and Hepatology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland.
| | - Hannah Vaughan
- Translational Tissue Engineering Center, Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Rafiquel Sarker
- Division of Gastroenterology and Hepatology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Savannah Est-Witte
- Translational Tissue Engineering Center, Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Molee Chakraborty
- Division of Gastroenterology and Hepatology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Nicholas W Baetz
- Division of Gastroenterology and Hepatology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Hongzhe Yu
- Translational Tissue Engineering Center, Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, University of California Davis, Davis, California; Department of Anesthesiology and Pain Medicine, University of California Davis, Davis, California
| | - George McNamara
- Division of Gastroenterology and Hepatology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Jordan J Green
- Translational Tissue Engineering Center, Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Chung-Ming Tse
- Division of Gastroenterology and Hepatology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Mark Donowitz
- Division of Gastroenterology and Hepatology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
| |
Collapse
|
3
|
Donowitz M, Sarker R, Lin R, McNamara G, Tse CM, Singh V. Identification of Intestinal NaCl Absorptive-Anion Secretory Cells: Potential Functional Significance. Front Physiol 2022; 13:892112. [PMID: 35928564 PMCID: PMC9343792 DOI: 10.3389/fphys.2022.892112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 05/18/2022] [Indexed: 11/13/2022] Open
Abstract
Use of human enteroids studied in the undifferentiated and differentiated state that mimic the intestinal crypt and villus, respectively, has allowed studies of multiple enterocyte populations, including a large population of enterocytes that are transitioning from the crypt to the villus. This population expresses NHE3, DRA, and CFTR, representing a combination of Na absorptive and anion secretory functions. In this cell population, these three transporters physically interact, which affects their baseline and regulated activities. A study of this cell population and differentiated Caco-2 cells transduced with NHE3 and endogenously expressing DRA and CFTR has allowed an understanding of previous studies in which cAMP seemed to stimulate and inhibit DRA at the same time. Understanding the contributions of these cells to overall intestinal transport function as part of the fasting and post-prandial state and their contribution to the pathophysiology of diarrheal diseases and some conditions with constipation will allow new approaches to drug development.
Collapse
Affiliation(s)
- Mark Donowitz
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
- Department of Physiology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
- *Correspondence: Mark Donowitz,
| | - Rafiquel Sarker
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Ruxian Lin
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - George McNamara
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Chung Ming Tse
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Varsha Singh
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
| |
Collapse
|
4
|
Bogdanic E, Müller T, Heinz-Erian P, Garczarczyk-Asim D, Janecke AR, Rückel A. Further delineation of SLC9A3-related congenital sodium diarrhea. Mol Genet Genomic Med 2022; 10:e2000. [PMID: 35775128 PMCID: PMC9356552 DOI: 10.1002/mgg3.2000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Revised: 04/06/2022] [Accepted: 05/13/2022] [Indexed: 11/05/2022] Open
Abstract
BACKGROUND Congenital sodium diarrhea (CSD) is a rare enteropathy displaying both broad variability in clinical severity and genetic locus and allelic heterogeneity. Eleven CSD patients were reported so far with SLC9A3 variants that impair the function of the encoded intestinal sodium-proton exchanger 3 (NHE3). METHODS We report a 4-year-old patient, born prematurely in the 35th week of gestation, with antenatal polyhydramnios and dilated intestinal loops, and with diarrhea of congenital onset, 2-6 times a day, and with polydipsia. She thrived age-appropriately under a normal family diet. Serum sodium levels were repeatedly normal but urinary sodium excretion was low. Exome sequencing revealed compound heterozygous variants in SLC9A3 as the likely cause of the congenital diarrhea. RESULTS While exome sequencing did not reveal pathogenic or likely pathogenic variants in other genes that cause syndromic or non-syndromic forms of congenital and intractable diarrheas, we identified novel compound heterozygous variants in SLC9A3, a complex allele with two missense changes, NP_004165.2:p.[Ser331Leu;Val449Ile] and in-trans the missense variant p.(Phe451Ser). CONCLUSION The clinical phenotype here appears to localize to the milder end of the known CSD spectrum, and the identified variants suggest that this is the twelfth patient reported to date with CSD due to mutations in SLC9A3.
Collapse
Affiliation(s)
- Ema Bogdanic
- Department of Pediatrics I, Medical University of Innsbruck, Innsbruck, Austria
| | - Thomas Müller
- Department of Pediatrics I, Medical University of Innsbruck, Innsbruck, Austria
| | - Peter Heinz-Erian
- Department of Pediatrics I, Medical University of Innsbruck, Innsbruck, Austria
| | | | - Andreas R Janecke
- Department of Pediatrics I, Medical University of Innsbruck, Innsbruck, Austria.,Division of Human Genetics, Medical University of Innsbruck, Innsbruck, Austria
| | - Aline Rückel
- Department of Pediatrics, University of Erlangen, Erlangen, Germany
| |
Collapse
|
5
|
Gao AYL, Lourdin-De Filippis E, Orlowski J, McKinney RA. Roles of Endomembrane Alkali Cation/Proton Exchangers in Synaptic Function and Neurodevelopmental Disorders. Front Physiol 2022; 13:892196. [PMID: 35547574 PMCID: PMC9081726 DOI: 10.3389/fphys.2022.892196] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 03/30/2022] [Indexed: 12/25/2022] Open
Abstract
Endomembrane alkali cation (Na+, K+)/proton (H+) exchangers (eNHEs) are increasingly associated with neurological disorders. These eNHEs play integral roles in regulating the luminal pH, processing, and trafficking of cargo along the secretory (Golgi and post-Golgi vesicles) and endocytic (early, recycling, and late endosomes) pathways, essential regulatory processes vital for neuronal development and plasticity. Given the complex morphology and compartmentalization of multipolar neurons, the contribution of eNHEs in maintaining optimal pH homeostasis and cargo trafficking is especially significant during periods of structural and functional development and remodeling. While the importance of eNHEs has been demonstrated in a variety of non-neuronal cell types, their involvement in neuronal function is less well understood. In this review, we will discuss their emerging roles in excitatory synaptic function, particularly as it pertains to cellular learning and remodeling. We will also explore their connections to neurodevelopmental conditions, including intellectual disability, autism, and attention deficit hyperactivity disorders.
Collapse
Affiliation(s)
- Andy Y L Gao
- Integrated Program in Neuroscience, McGill University, Montreal, QC, Canada.,Department of Pharmacology & Therapeutics, McGill University, Montreal, QC, Canada
| | | | - John Orlowski
- Department of Physiology, McGill University, Montreal, QC, Canada
| | - R Anne McKinney
- Department of Pharmacology & Therapeutics, McGill University, Montreal, QC, Canada
| |
Collapse
|
6
|
Jacobs JW, Leadbetter MR, Bell N, Koo-McCoy S, Carreras CW, He L, Kohler J, Kozuka K, Labonté ED, Navre M, Spencer AG, Charmot D. Discovery of Tenapanor: A First-in-Class Minimally Systemic Inhibitor of Intestinal Na +/H + Exchanger Isoform 3. ACS Med Chem Lett 2022; 13:1043-1051. [PMID: 35859876 PMCID: PMC9290029 DOI: 10.1021/acsmedchemlett.2c00037] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
![]()
We present herein
the design, synthesis, and optimization of gut-restricted
inhibitors of Na+/H+ exchanger isoform 3 (NHE3).
NHE3 is predominantly expressed in the kidney and gastrointestinal
tract where it acts as the major absorptive sodium transporter. We
desired minimally systemic agents that would block sodium absorption
in the gastrointestinal tract but avoid exposure in the kidney. Starting
with a relatively low-potency highly bioavailable hit compound (1), potent and minimally absorbed NHE3 inhibitors were designed,
culminating with the discovery of tenapanor (28). Tenapanor
has been approved by the U.S. Food and Drug Administration (FDA) for
the treatment of irritable bowel syndrome with constipation in adults.
Collapse
Affiliation(s)
- Jeffrey W. Jacobs
- Ardelyx, Inc., 400 Fifth Avenue, Suite 210, Waltham, Massachusetts 02451, United States
| | - Michael R. Leadbetter
- Ardelyx, Inc., 400 Fifth Avenue, Suite 210, Waltham, Massachusetts 02451, United States
| | - Noah Bell
- Ardelyx, Inc., 400 Fifth Avenue, Suite 210, Waltham, Massachusetts 02451, United States
| | - Samantha Koo-McCoy
- Ardelyx, Inc., 400 Fifth Avenue, Suite 210, Waltham, Massachusetts 02451, United States
| | | | - Limin He
- Ardelyx, Inc., 400 Fifth Avenue, Suite 210, Waltham, Massachusetts 02451, United States
| | - Jill Kohler
- Ardelyx, Inc., 400 Fifth Avenue, Suite 210, Waltham, Massachusetts 02451, United States
| | - Kenji Kozuka
- Ardelyx, Inc., 400 Fifth Avenue, Suite 210, Waltham, Massachusetts 02451, United States
| | - Eric D. Labonté
- Ardelyx, Inc., 400 Fifth Avenue, Suite 210, Waltham, Massachusetts 02451, United States
| | - Marc Navre
- Ardelyx, Inc., 400 Fifth Avenue, Suite 210, Waltham, Massachusetts 02451, United States
| | - Andrew G. Spencer
- Ardelyx, Inc., 400 Fifth Avenue, Suite 210, Waltham, Massachusetts 02451, United States
| | - Dominique Charmot
- Ardelyx, Inc., 400 Fifth Avenue, Suite 210, Waltham, Massachusetts 02451, United States
| |
Collapse
|
7
|
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.
Collapse
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
| |
Collapse
|
8
|
Matsuoka R, Fudim R, Jung S, Zhang C, Bazzone A, Chatzikyriakidou Y, Robinson CV, Nomura N, Iwata S, Landreh M, Orellana L, Beckstein O, Drew D. Structure, mechanism and lipid-mediated remodeling of the mammalian Na +/H + exchanger NHA2. Nat Struct Mol Biol 2022; 29:108-120. [PMID: 35173351 PMCID: PMC8850199 DOI: 10.1038/s41594-022-00738-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 12/14/2021] [Indexed: 11/09/2022]
Abstract
The Na+/H+ exchanger SLC9B2, also known as NHA2, correlates with the long-sought-after Na+/Li+ exchanger linked to the pathogenesis of diabetes mellitus and essential hypertension in humans. Despite the functional importance of NHA2, structural information and the molecular basis for its ion-exchange mechanism have been lacking. Here we report the cryo-EM structures of bison NHA2 in detergent and in nanodiscs, at 3.0 and 3.5 Å resolution, respectively. The bison NHA2 structure, together with solid-state membrane-based electrophysiology, establishes the molecular basis for electroneutral ion exchange. NHA2 consists of 14 transmembrane (TM) segments, rather than the 13 TMs previously observed in mammalian Na+/H+ exchangers (NHEs) and related bacterial antiporters. The additional N-terminal helix in NHA2 forms a unique homodimer interface with a large intracellular gap between the protomers, which closes in the presence of phosphoinositol lipids. We propose that the additional N-terminal helix has evolved as a lipid-mediated remodeling switch for the regulation of NHA2 activity.
Collapse
Affiliation(s)
- Rei Matsuoka
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Roman Fudim
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.
| | - Sukkyeong Jung
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Chenou Zhang
- Center for Biological Physics, Department of Physics, Arizona State University, Tempe, AZ, USA
| | | | | | | | - Norimichi Nomura
- Graduate School of Medicine, Kyoto University, Konoe-cho, Yoshida, Sakyo-ku, Kyoto, Japan
| | - So Iwata
- Graduate School of Medicine, Kyoto University, Konoe-cho, Yoshida, Sakyo-ku, Kyoto, Japan
| | - Michael Landreh
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Laura Orellana
- Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden
| | - Oliver Beckstein
- Center for Biological Physics, Department of Physics, Arizona State University, Tempe, AZ, USA.
| | - David Drew
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.
| |
Collapse
|
9
|
Kovesdy CP, Adebiyi A, Rosenbaum D, Jacobs JW, Quarles LD. Novel Treatments from Inhibition of the Intestinal Sodium-Hydrogen Exchanger 3. Int J Nephrol Renovasc Dis 2021; 14:411-420. [PMID: 34880650 PMCID: PMC8646223 DOI: 10.2147/ijnrd.s334024] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 11/11/2021] [Indexed: 12/31/2022] Open
Abstract
Plasma membrane sodium–hydrogen exchangers (NHE) transport Na+ into cells in exchange for H+. While there are nine isoforms of NHE in humans, this review focuses on the NHE3 isoform, which is abundantly expressed in the gastrointestinal tract, where it plays a key role in acid–base balance and water homeostasis. NHE3 inhibition in the small intestine results in luminal sodium and water retention, leading to a general decrease in paracellular water flux and diffusional driving force, reduced intestinal sodium absorption, and increased stool sodium excretion. The resulting softer and more frequent stools are the rationale for the development of tenapanor as a novel, first-in-class NHE3 inhibitor to treat irritable bowel syndrome with constipation. NHE3 also has additional therapeutic implications in nephrology. Inhibition of intestinal NHE3 also lowers blood pressure by reducing intestinal sodium absorption. Perhaps, the most novel effect is its ability to decrease intestinal phosphate absorption by inhibiting the paracellular phosphate absorption pathway. Therefore, selective pharmacological inhibition of NHE3 could be a potential therapeutic strategy to treat not only heart failure and hypertension but also hyperphosphatemia. This review presents an overview of the molecular and physiological functions of NHE3 and discusses how these functions translate to potential clinical applications in nephrology.
Collapse
Affiliation(s)
- Csaba P Kovesdy
- Division of Nephrology, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Adebowale Adebiyi
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, USA
| | | | | | - L Darryl Quarles
- Division of Nephrology, University of Tennessee Health Science Center, Memphis, TN, USA
| |
Collapse
|
10
|
Ran L, Yan T, Zhang Y, Niu Z, Kan Z, Song Z. The recycling regulation of sodium-hydrogen exchanger isoform 3(NHE3) in epithelial cells. Cell Cycle 2021; 20:2565-2582. [PMID: 34822321 DOI: 10.1080/15384101.2021.2005274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
As the main exchanger of electroneutral NaCl absorption, sodium-hydrogen exchanger isoform 3 (NHE3) circulates in the epithelial brush border (BB) and intracellular compartments in a multi-protein complex. The size of the NHE3 complex changes during rapid regulation events. Recycling regulation of NHE3 in epithelial cells can be roughly divided into three stages. First, when stimulated by Ca2+, cGMP, and cAMP-dependent signaling pathways, NHE3 is converted from an immobile complex found at the apical microvilli (MV) into an easily internalized and mobile form that relocates to a compartment near the base of the MV. Second, NHE3 is internalized by clathrin and albumin-dependent pathways into cytoplasmic endosomal compartments, where the complex is reprocessed and reassembled. Finally, NHE3 is translocated from the recycling endosomes (REs) to the apex of epithelial cells, a process that can be stimulated by an increase in sodium-glucose cotransporter 1 (SGLT1) activity, epidermal growth factor receptor (EGFR) signaling, Ca2+ signaling, and binding to βPix and SH3 and multiple ankyrin repeat domains 2 (Shank2) proteins. This review describes the molecular steps and protein interactions involved in the recycling movement of NHE3 from the apex of epithelial cells, into vesicles, where it is reprocessed and reassembled, and returned to its original location on the plasma membrane, where it exerts its physiological function.
Collapse
Affiliation(s)
- Ling Ran
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Southwest University, Rongchang, China
| | - Tao Yan
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Xinjiang Agricultural University, Urumqi, China
| | - Yiling Zhang
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Southwest University, Rongchang, China
| | - Zheng Niu
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Southwest University, Rongchang, China
| | - Zifei Kan
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Southwest University, Rongchang, China
| | - Zhenhui Song
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Southwest University, Rongchang, China
| |
Collapse
|
11
|
Grosche S, Marenholz I, Esparza-Gordillo J, Arnau-Soler A, Pairo-Castineira E, Rüschendorf F, Ahluwalia TS, Almqvist C, Arnold A, Baurecht H, Bisgaard H, Bønnelykke K, Brown SJ, Bustamante M, Curtin JA, Custovic A, Dharmage SC, Esplugues A, Falchi M, Fernandez-Orth D, Ferreira MAR, Franke A, Gerdes S, Gieger C, Hakonarson H, Holt PG, Homuth G, Hubner N, Hysi PG, Jarvelin MR, Karlsson R, Koppelman GH, Lau S, Lutz M, Magnusson PKE, Marks GB, Müller-Nurasyid M, Nöthen MM, Paternoster L, Pennell CE, Peters A, Rawlik K, Robertson CF, Rodriguez E, Sebert S, Simpson A, Sleiman PMA, Standl M, Stölzl D, Strauch K, Szwajda A, Tenesa A, Thompson PJ, Ullemar V, Visconti A, Vonk JM, Wang CA, Weidinger S, Wielscher M, Worth CL, Xu CJ, Lee YA. Rare variant analysis in eczema identifies exonic variants in DUSP1, NOTCH4 and SLC9A4. Nat Commun 2021; 12:6618. [PMID: 34785669 PMCID: PMC8595373 DOI: 10.1038/s41467-021-26783-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2020] [Accepted: 10/21/2021] [Indexed: 11/10/2022] Open
Abstract
Previous genome-wide association studies revealed multiple common variants involved in eczema but the role of rare variants remains to be elucidated. Here, we investigate the role of rare variants in eczema susceptibility. We meta-analyze 21 study populations including 20,016 eczema cases and 380,433 controls. Rare variants are imputed with high accuracy using large population-based reference panels. We identify rare exonic variants in DUSP1, NOTCH4, and SLC9A4 to be associated with eczema. In DUSP1 and NOTCH4 missense variants are predicted to impact conserved functional domains. In addition, five novel common variants at SATB1-AS1/KCNH8, TRIB1/LINC00861, ZBTB1, TBX21/OSBPL7, and CSF2RB are discovered. While genes prioritized based on rare variants are significantly up-regulated in the skin, common variants point to immune cell function. Over 20% of the single nucleotide variant-based heritability is attributable to rare and low-frequency variants. The identified rare/low-frequency variants located in functional protein domains point to promising targets for novel therapeutic approaches to eczema. Genetic studies of eczema to date have mostly explored common genetic variation. Here, the authors perform a large meta-analysis for common and rare variants and discover 8 loci associated with eczema. Over 20% of the heritability of the condition is attributable to rare variants.
Collapse
Affiliation(s)
- Sarah Grosche
- Max-Delbrück-Center (MDC) for Molecular Medicine, Berlin, Germany.,Clinic for Pediatric Allergy, Experimental and Clinical Research Center, Charité University Medical Center, Berlin, Germany.,CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Ingo Marenholz
- Max-Delbrück-Center (MDC) for Molecular Medicine, Berlin, Germany.,Clinic for Pediatric Allergy, Experimental and Clinical Research Center, Charité University Medical Center, Berlin, Germany
| | - Jorge Esparza-Gordillo
- Max-Delbrück-Center (MDC) for Molecular Medicine, Berlin, Germany.,Clinic for Pediatric Allergy, Experimental and Clinical Research Center, Charité University Medical Center, Berlin, Germany.,GlaxoSmithKline, Stevenage, UK
| | - Aleix Arnau-Soler
- Max-Delbrück-Center (MDC) for Molecular Medicine, Berlin, Germany.,Clinic for Pediatric Allergy, Experimental and Clinical Research Center, Charité University Medical Center, Berlin, Germany
| | - Erola Pairo-Castineira
- Roslin Institute, University of Edinburgh, Edinburgh, UK.,MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Western General Hospital, Edinburgh, UK
| | | | - Tarunveer S Ahluwalia
- COPSAC, Copenhagen Prospective Studies on Asthma in Childhood, Herlev and Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark.,Steno Diabetes Center Copenhagen, Gentofte, Denmark
| | - Catarina Almqvist
- Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden.,Astrid Lindgren Children's Hospital, Karolinska University Hospital, Stockholm, Sweden
| | - Andreas Arnold
- Clinic and Polyclinic of Dermatology, University Medicine Greifswald, Greifswald, Germany
| | | | - Hansjörg Baurecht
- Department of Dermatology, Allergology and Venereology, University Hospital Schleswig-Holstein, Kiel, Germany.,Department of Epidemiology and Preventive Medicine, University Regensburg, Regensburg, Germany
| | - Hans Bisgaard
- COPSAC, Copenhagen Prospective Studies on Asthma in Childhood, Herlev and Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark
| | - Klaus Bønnelykke
- COPSAC, Copenhagen Prospective Studies on Asthma in Childhood, Herlev and Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark
| | - Sara J Brown
- Institute of Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh, UK
| | - Mariona Bustamante
- ISGlobal, Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain
| | - John A Curtin
- Division of Infection Immunity and Respiratory Medicine, School of Biological Sciences, The University of Manchester, Manchester Academic Health Science Centre and Manchester University NHS Foundation Trust, Manchester, UK
| | - Adnan Custovic
- National Lung and Heart Institute, Imperial College London, London, UK
| | - Shyamali C Dharmage
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Australia
| | - Ana Esplugues
- Nursing School, University of Valencia, FISABIO-University Jaume I-University of Valencia Joint Research Unit of Epidemiology and Environmental Health, CIBERESP, Valencia, Spain
| | - Mario Falchi
- Department of Twins Research and Genetic Epidemiology, King's College London, London, UK
| | | | - Manuel A R Ferreira
- Genetics and Computational Biology, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Andre Franke
- Institute of Clinical Molecular Biology, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Sascha Gerdes
- Department of Dermatology, Allergology and Venereology, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Christian Gieger
- Research Unit Molecular Epidemiology, Helmholtz Center Munich - German Research Center for Environmental Health, Neuherberg, Germany
| | - Hakon Hakonarson
- Center for Applied Genomics, Children's Hospital of Philadelphia, and Division of Human Genetics, Department of Pediatrics, The Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Patrick G Holt
- Telethon Kids Institute, The University of Western Australia, Perth, Australia
| | - Georg Homuth
- Department of Functional Genomics, Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Norbert Hubner
- Max-Delbrück-Center (MDC) for Molecular Medicine, Berlin, Germany
| | - Pirro G Hysi
- Department of Twins Research and Genetic Epidemiology, King's College London, London, UK
| | - Marjo-Riitta Jarvelin
- Department of Epidemiology and Biostatistics, MRC-PHE Centre for Environment & Health, School of Public Health, Imperial College London, London, UK.,Center for Life Course Health Research, Faculty of Medicine, University of Oulu, Oulu, Finland.,Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Robert Karlsson
- Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden
| | - Gerard H Koppelman
- Department of Pediatric Pulmonology and Pediatric Allergology, University of Groningen, University Medical Center Groningen, GRIAC Research Institute, Groningen, the Netherlands
| | - Susanne Lau
- Department of Pediatric Pulmonology, Immunology and Intensive Care Medicine, Charité University Medical Center, Berlin, Germany
| | - Manuel Lutz
- Institute of Genetic Epidemiology, Helmholtz Center Munich-German Research Center for Environmental Health, Neuherberg, Germany
| | - Patrik K E Magnusson
- Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden
| | - Guy B Marks
- Woolcock Institute of Medical Research, University of Sydney, Sydney, Australia
| | - Martina Müller-Nurasyid
- Institute of Genetic Epidemiology, Helmholtz Center Munich-German Research Center for Environmental Health, Neuherberg, Germany.,Institute for Medical Information Processing, Biometry, and Epidemiology (IBE), Faculty of Medicine, LMU Munich, Munich, Germany.,Institute of Medical Biostatistics, Epidemiology and Informatics (IMBEI), University Medical Center, Johannes Gutenberg University, Mainz, Germany
| | - Markus M Nöthen
- Institute of Human Genetics, University of Bonn, School of Medicine & University Hospital Bonn, Bonn, Germany
| | - Lavinia Paternoster
- MRC Integrative Epidemiology Unit, Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Craig E Pennell
- School of Medicine and Public Health, Faculty of Medicine and Health, The University of Newcastle, Newcastle, Australia
| | - Annette Peters
- Institute of Epidemiology, Helmholtz Center Munich-German Research Center for Environmental Health, Neuherberg, Germany
| | - Konrad Rawlik
- Roslin Institute, University of Edinburgh, Edinburgh, UK
| | - Colin F Robertson
- Respiratory Research, Murdoch Children's Research Institute, Melbourne, Australia
| | - Elke Rodriguez
- Department of Dermatology, Allergology and Venereology, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Sylvain Sebert
- Department of Epidemiology and Biostatistics, MRC-PHE Centre for Environment & Health, School of Public Health, Imperial College London, London, UK.,Center for Life Course Health Research, Faculty of Medicine, University of Oulu, Oulu, Finland.,Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Angela Simpson
- Division of Infection Immunity and Respiratory Medicine, School of Biological Sciences, The University of Manchester, Manchester Academic Health Science Centre and Manchester University NHS Foundation Trust, Manchester, UK
| | - Patrick M A Sleiman
- Center for Applied Genomics, Children's Hospital of Philadelphia, and Division of Human Genetics, Department of Pediatrics, The Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Marie Standl
- Institute of Epidemiology, Helmholtz Center Munich-German Research Center for Environmental Health, Neuherberg, Germany
| | - Dora Stölzl
- Department of Dermatology, Allergology and Venereology, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Konstantin Strauch
- Institute of Genetic Epidemiology, Helmholtz Center Munich-German Research Center for Environmental Health, Neuherberg, Germany.,Institute for Medical Information Processing, Biometry, and Epidemiology (IBE), Faculty of Medicine, LMU Munich, Munich, Germany.,Institute of Medical Biostatistics, Epidemiology and Informatics (IMBEI), University Medical Center, Johannes Gutenberg University, Mainz, Germany
| | - Agnieszka Szwajda
- Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden
| | - Albert Tenesa
- Roslin Institute, University of Edinburgh, Edinburgh, UK.,MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Western General Hospital, Edinburgh, UK.,Centre for Global Health Research, Usher Institute of Population Health Sciences and Informatics, Edinburgh, UK
| | - Philip J Thompson
- Institute for Respiratory Health and Centre for Respiratory Health, School of Biomedical Sciences, University of Western Australia, Nedlands, Australia
| | - Vilhelmina Ullemar
- Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden
| | - Alessia Visconti
- Department of Twins Research and Genetic Epidemiology, King's College London, London, UK
| | - Judith M Vonk
- Department of Epidemiology, University of Groningen, University Medical Center Groningen, GRIAC Research Institute, Groningen, the Netherlands
| | - Carol A Wang
- School of Medicine and Public Health, Faculty of Medicine and Health, The University of Newcastle, Newcastle, Australia
| | - Stephan Weidinger
- Department of Dermatology, Allergology and Venereology, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Matthias Wielscher
- Department of Epidemiology and Biostatistics, MRC-PHE Centre for Environment & Health, School of Public Health, Imperial College London, London, UK
| | | | - Chen-Jian Xu
- Department of Pediatric Pulmonology and Pediatric Allergology, University of Groningen, University Medical Center Groningen, GRIAC Research Institute, Groningen, the Netherlands.,Department of Gastroenterology, Hepatology and Endocrinology, Centre for individualized infection medicine (CIIM), Hannover Medical School, Hannover, Germany
| | - Young-Ae Lee
- Max-Delbrück-Center (MDC) for Molecular Medicine, Berlin, Germany. .,Clinic for Pediatric Allergy, Experimental and Clinical Research Center, Charité University Medical Center, Berlin, Germany.
| |
Collapse
|
12
|
Nickerson AJ, Rajendran VM. Flupirtine enhances NHE-3-mediated Na + absorption in rat colon via an ENS-dependent mechanism. Am J Physiol Gastrointest Liver Physiol 2021; 321:G185-G199. [PMID: 34132108 PMCID: PMC8410105 DOI: 10.1152/ajpgi.00158.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 06/11/2021] [Accepted: 06/11/2021] [Indexed: 01/31/2023]
Abstract
Recent studies in our lab have shown that the KV7 channel activator, flupirtine, inhibits colonic epithelial Cl- secretion through effects on submucosal neurons of the enteric nervous system (ENS). We hypothesized that flupirtine would also stimulate Na+ absorption as a result of reduced secretory ENS input to the epithelium. To test this hypothesis, unidirectional 22Na+ fluxes were measured under voltage-clamped conditions. Pharmacological approaches using an Ussing-style recording chamber combined with immunofluorescence microscopy techniques were used to determine the effect of flupirtine on active Na+ transport in the rat colon. Flupirtine stimulated electroneutral Na+ absorption in partially seromuscular-stripped colonic tissues, while simultaneously inhibiting short-circuit current (ISC; i.e., Cl- secretion). Both of these effects were attenuated by pretreatment with the ENS inhibitor, tetrodotoxin. The Na+/H+ exchanger isoform 3 (NHE-3)-selective inhibitor, S3226, significantly inhibited flupirtine-stimulated Na+ absorption, whereas the NHE-2-selective inhibitor HOE-694 did not. NHE-3 localization near the apical membranes of surface epithelial cells was also more apparent in flupirtine-treated colon versus control. Flupirtine did not alter epithelial Na+ channel (ENaC)-mediated Na+ absorption in distal colonic tissues obtained from hyperaldosteronaemic rats and had no effect in the normal ileum but did stimulate Na+ absorption in the proximal colon. Finally, the parallel effects of flupirtine on ISC (Cl- secretion) and Na+ absorption were significantly correlated with each other. Together, these data indicate that flupirtine stimulates NHE-3-dependent Na+ absorption, likely as a result of reduced stimulatory input to the colonic epithelium by submucosal ENS neurons.NEW & NOTEWORTHY We present a novel mechanism regarding regulation of epithelial ion transport by enteric neurons. Activation of neuronal KV7 K+ channels markedly stimulates Na+ absorption and inhibits Cl- secretion across the colonic epithelium. This may be useful in developing new treatments for diarrheal disorders, such as irritable bowel syndrome with diarrhea (IBS-D).
Collapse
Affiliation(s)
- Andrew J Nickerson
- Departments of Physiology, Pharmacology and Neuroscience, West Virginia University School of Medicine, Morgantown, West Virginia
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, West Virginia
| | - Vazhaikkurichi M Rajendran
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, West Virginia
- Department of Medicine, West Virginia University School of Medicine, Morgantown, West Virginia
| |
Collapse
|
13
|
Zhou K, Amiri M, Salari A, Yu Y, Xu H, Seidler U, Nikolovska K. Functional characterization of the sodium/hydrogen exchanger 8 and its role in proliferation of colonic epithelial cells. Am J Physiol Cell Physiol 2021; 321:C471-C488. [PMID: 34288721 DOI: 10.1152/ajpcell.00582.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Intestinal NaCl, HCO3-, and fluid absorption are strongly dependent on apical Na+/H+ exchange. The intestine expresses three presumably apical sodium-hydrogen exchanger (NHE) isoforms: NHE2, NHE3, and NHE8. We addressed the role of NHE8 [solute carrier 9A8 (SLC9A8)] and its interplay with NHE2 (SLC9A2) in luminal proton extrusion during acute and chronic enterocyte acidosis and studied the differential effects of NHE8 and NHE2 on enterocyte proliferation. In contrast to NHE3, which was upregulated in differentiated versus undifferentiated colonoids, the expression of NHE2 and NHE8 remained constant during differentiation of colonoids and Caco2Bbe cells. Heterogeneously expressed Flag-tagged rat (r)Nhe8 and human (h)NHE8 translocated to the apical membrane of Caco2Bbe cells. rNhe8 and hNHE8, when expressed in NHE-deficient PS120 fibroblasts showed higher sensitivity to HOE642 compared to NHE2. Lentiviral shRNA knockdown of endogenous NHE2 in Caco2Bbe cells (C2Bbe/shNHE2) resulted in a decreased steady-state intracellular pH (pHi), an increased NHE8 mRNA expression, and augmented NHE8-mediated apical NHE activity. Lentiviral shRNA knockdown of endogenous NHE8 in Caco2Bbe cells (C2Bbe/shNHE8) resulted in a decreased steady-state pHi as well, accompanied by decreased NHE2 mRNA expression and activity, which together contributed to reduced apical NHE activity in the NHE8-knockdown cells. Chronic acidosis increased NHE8 but not NHE2 mRNA expression. Alterations in NHE2 and NHE8 expression/activity affected proliferation, with C2Bbe/shNHE2 cells having lower and C2Bbe/shNHE8 having higher proliferative capacity, accompanied by amplified ERK1/2 signaling pathway and increased EGFR expression in the latter cell line. Thus, both Na+/H+ exchangers have distinct functions during cellular homeostasis by triggering different signaling pathways to regulate cellular proliferation and pHi control.
Collapse
Affiliation(s)
- Kunyan Zhou
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Mahdi Amiri
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Azam Salari
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Yan Yu
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Hua Xu
- Department of Pediatrics, University of Arizona Health Science Center, Tucson, Arizona
| | - Ursula Seidler
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Katerina Nikolovska
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| |
Collapse
|
14
|
Pizzagalli MD, Bensimon A, Superti‐Furga G. A guide to plasma membrane solute carrier proteins. FEBS J 2021; 288:2784-2835. [PMID: 32810346 PMCID: PMC8246967 DOI: 10.1111/febs.15531] [Citation(s) in RCA: 181] [Impact Index Per Article: 60.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 08/07/2020] [Accepted: 08/17/2020] [Indexed: 12/13/2022]
Abstract
This review aims to serve as an introduction to the solute carrier proteins (SLC) superfamily of transporter proteins and their roles in human cells. The SLC superfamily currently includes 458 transport proteins in 65 families that carry a wide variety of substances across cellular membranes. While members of this superfamily are found throughout cellular organelles, this review focuses on transporters expressed at the plasma membrane. At the cell surface, SLC proteins may be viewed as gatekeepers of the cellular milieu, dynamically responding to different metabolic states. With altered metabolism being one of the hallmarks of cancer, we also briefly review the roles that surface SLC proteins play in the development and progression of cancer through their influence on regulating metabolism and environmental conditions.
Collapse
Affiliation(s)
- Mattia D. Pizzagalli
- CeMM, Research Center for Molecular Medicine of the Austrian Academy of SciencesViennaAustria
| | - Ariel Bensimon
- CeMM, Research Center for Molecular Medicine of the Austrian Academy of SciencesViennaAustria
| | - Giulio Superti‐Furga
- CeMM, Research Center for Molecular Medicine of the Austrian Academy of SciencesViennaAustria
- Center for Physiology and PharmacologyMedical University of ViennaAustria
| |
Collapse
|
15
|
Cheuvront SN, Kenefick RW, Luque L, Mitchell KM, Vidyasagar S. Are oral rehydration solutions optimized for treating diarrhea? Nutr Health 2021; 27:461-465. [PMID: 33583247 DOI: 10.1177/0260106021991641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND A historical turning point occurred in the treatment of diarrhea when it was discovered that glucose could enhance intestinal sodium and water absorption. Adding glucose to salt water (oral rehydration solution, ORS) more efficiently replaced intestinal water and salt losses. AIM Provide a novel hypothesis to explain why mainstream use of ORS has been strongly recommended, but weakly adopted. METHODS Traditional (absorptive) and novel (secretory) physiological functions of glucose in an ORS were reviewed. RESULTS Small amounts of glucose can stimulate both intestinal absorption and secretion. Glucose can exacerbate a net secretory state and may aggravate pathogen-induced diarrhea, particularly for pathogens that affect glucose transport. CONCLUSION A hypothesis is made to explain why glucose-based ORS does not appreciably reduce diarrheal stool volume and why modern food science initiatives should focus on ORS formulations that replace water and electrolytes while also reducing stool volume and duration of diarrhea.
Collapse
|
16
|
Al Barbandi M, Defreitas MJ, Infante JC, Morsi M, Arroyo Parejo Drayer PA, Katsoufis CP, Seeherunvong W, Chandar J, Burke GW, Abitbol CL. Case Report: Uroenteric Fistula in a Pediatric-en-bloc Kidney Transplant Manifests as Deceptive Watery Diarrhea and Normal Anion Gap Acidosis. Front Pediatr 2021; 9:687396. [PMID: 34322462 PMCID: PMC8310905 DOI: 10.3389/fped.2021.687396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 06/16/2021] [Indexed: 12/02/2022] Open
Abstract
Introduction: The diagnosis of a post-surgical uroenteric fistula can be challenging and may be delayed for months after symptoms begin. A normal anion gap metabolic acidosis has been reported in up to 100% of patients after ureterosigmoidostomy, and bladder substitution using small bowel and/or colonic segments. Here, we describe a rare case of a pediatric patient who developed a uroenteric fistula from the transplant ureters into the small bowel, after an en-bloc kidney transplantation resulting in profound acidosis and deceptive watery diarrhea. Case Presentation: The patient is an 8-year-old girl with end stage kidney disease (ESKD) secondary to focal segmental glomerulosclerosis. Through a right retroperitoneal approach, she underwent a right native nephrectomy and a pediatric deceased donor en-bloc kidney transplant including two separate ureters. One month later, she had a renal allograft biopsy for suspected rejection. During the week after the biopsy, she experienced abdominal pain followed by watery diarrhea and metabolic acidosis requiring continuous bicarbonate/acetate infusions. An extensive gastro-intestinal evaluation for the cause of the diarrhea including endoscopy was inconclusive. The urine output decreased to <500 ml daily; although, the kidney function remained normal. After 2 weeks of unexplained watery diarrhea a magnetic resonance urogram with contrast was performed which demonstrated extravasation of urine from both ureters with fistulization into the small bowel. She underwent corrective surgery which identified the fistulous tract, which was resected and both ureters were re-implanted. The diarrhea and acidosis resolved, and she has maintained normal renal allograft function for over 1 year. Conclusion: An important aspect in the early diagnosis of a uroenteric fistula is the sudden onset of severe hyperchloremic metabolic acidosis that results when urine is diverted into the intestinal tract. The mechanism is similar to that described in cases of urinary diversions and/or bladder augmentation using the intestine. Important diagnostic tools are the measurements of solute excretion and pH in the urine as compared to the "watery diarrhea" or bowel output. Summary: We describe a case of a uroenteric fistula in a pediatric-en-bloc kidney transplant patient that went undiagnosed for almost 3 weeks due to the deceptive nature of the watery diarrhea which was actually urine. A uroenteric fistula should be considered in the differential diagnosis of diarrhea and hyperchloremic metabolic acidosis as a complication of kidney transplant. The simultaneous comparison of stool and urine pH and solute excretions may lead to the diagnosis, appropriate imaging and surgical intervention.
Collapse
Affiliation(s)
- Malek Al Barbandi
- Division of Pediatric Nephrology, Department of Pediatrics, University of Miami/Holtz Children's Hospital, Miami, FL, United States
| | - Marissa J Defreitas
- Division of Pediatric Nephrology, Department of Pediatrics, University of Miami/Holtz Children's Hospital, Miami, FL, United States.,Division of Kidney/Pancreas Transplant, Department of Surgery, Miami Transplant Institute, University of Miami/Jackson Memorial Hospital, Miami, FL, United States
| | - Juan C Infante
- Department of Radiology (Voluntary), University of Miami/Jackson Memorial Hospital, Miami, FL, United States.,Department of Radiology, Nemours Children's Hospital/University of Central Florida, Orlando, FL, United States
| | - Mahmoud Morsi
- Division of Kidney/Pancreas Transplant, Department of Surgery, Miami Transplant Institute, University of Miami/Jackson Memorial Hospital, Miami, FL, United States
| | - Patricia A Arroyo Parejo Drayer
- Division of Pediatric Nephrology, Department of Pediatrics, University of Miami/Holtz Children's Hospital, Miami, FL, United States
| | - Chryso P Katsoufis
- Division of Pediatric Nephrology, Department of Pediatrics, University of Miami/Holtz Children's Hospital, Miami, FL, United States
| | - Wacharee Seeherunvong
- Division of Pediatric Nephrology, Department of Pediatrics, University of Miami/Holtz Children's Hospital, Miami, FL, United States
| | - Jayanthi Chandar
- Division of Pediatric Nephrology, Department of Pediatrics, University of Miami/Holtz Children's Hospital, Miami, FL, United States.,Division of Kidney/Pancreas Transplant, Department of Surgery, Miami Transplant Institute, University of Miami/Jackson Memorial Hospital, Miami, FL, United States
| | - George W Burke
- Division of Kidney/Pancreas Transplant, Department of Surgery, Miami Transplant Institute, University of Miami/Jackson Memorial Hospital, Miami, FL, United States
| | - Carolyn L Abitbol
- Division of Pediatric Nephrology, Department of Pediatrics, University of Miami/Holtz Children's Hospital, Miami, FL, United States
| |
Collapse
|
17
|
Winklemann I, Matsuoka R, Meier PF, Shutin D, Zhang C, Orellana L, Sexton R, Landreh M, Robinson CV, Beckstein O, Drew D. Structure and elevator mechanism of the mammalian sodium/proton exchanger NHE9. EMBO J 2020; 39:e105908. [PMID: 33118634 PMCID: PMC7737618 DOI: 10.15252/embj.2020105908] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 09/09/2020] [Accepted: 09/10/2020] [Indexed: 12/21/2022] Open
Abstract
Na+ /H+ exchangers (NHEs) are ancient membrane-bound nanomachines that work to regulate intracellular pH, sodium levels and cell volume. NHE activities contribute to the control of the cell cycle, cell proliferation, cell migration and vesicle trafficking. NHE dysfunction has been linked to many diseases, and they are targets of pharmaceutical drugs. Despite their fundamental importance to cell homeostasis and human physiology, structural information for the mammalian NHE was lacking. Here, we report the cryogenic electron microscopy structure of NHE isoform 9 (SLC9A9) from Equus caballus at 3.2 Å resolution, an endosomal isoform highly expressed in the brain and associated with autism spectrum (ASD) and attention deficit hyperactivity (ADHD) disorders. Despite low sequence identity, the NHE9 architecture and ion-binding site are remarkably similar to distantly related bacterial Na+ /H+ antiporters with 13 transmembrane segments. Collectively, we reveal the conserved architecture of the NHE ion-binding site, their elevator-like structural transitions, the functional implications of autism disease mutations and the role of phosphoinositide lipids to promote homodimerization that, together, have important physiological ramifications.
Collapse
Affiliation(s)
- Iven Winklemann
- Department of Biochemistry and BiophysicsStockholm UniversityStockholmSweden
| | - Rei Matsuoka
- Department of Biochemistry and BiophysicsStockholm UniversityStockholmSweden
| | - Pascal F Meier
- Department of Biochemistry and BiophysicsStockholm UniversityStockholmSweden
| | - Denis Shutin
- Department of ChemistryUniversity of OxfordOxfordUK
| | - Chenou Zhang
- Department of PhysicsCenter for Biological PhysicsArizona State UniversityTempeAZUSA
| | - Laura Orellana
- Department of Biochemistry and BiophysicsStockholm UniversityStockholmSweden
| | - Ricky Sexton
- Department of PhysicsCenter for Biological PhysicsArizona State UniversityTempeAZUSA
| | - Michael Landreh
- Department of Microbiology, Tumor and Cell BiologyKarolinska InstituteStockholmSweden
| | | | - Oliver Beckstein
- Department of PhysicsCenter for Biological PhysicsArizona State UniversityTempeAZUSA
| | - David Drew
- Department of Biochemistry and BiophysicsStockholm UniversityStockholmSweden
| |
Collapse
|
18
|
Brito D, Bettencourt P, Carvalho D, Ferreira J, Fontes-Carvalho R, Franco F, Moura B, Silva-Cardoso JC, de Melo RT, Fonseca C. Sodium-Glucose Co-transporter 2 Inhibitors in the Failing Heart: a Growing Potential. Cardiovasc Drugs Ther 2020; 34:419-436. [PMID: 32350793 PMCID: PMC7242490 DOI: 10.1007/s10557-020-06973-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Sodium-glucose co-transporter 2 inhibitors (SGLT2i) are a new drug class designed to treat patients with type 2 diabetes (T2D). However, cardiovascular outcome trials showed that SGLT2i also offer protection against heart failure (HF)-related events and cardiovascular mortality. These benefits appear to be independent of glycaemic control and have recently been demonstrated in the HF population with reduced ejection fraction (HFrEF), with or without T2D. This comprehensive, evidence-based review focuses on the published studies concerning HF outcomes with SGLT2i, discussing issues that may underlie the different results, along with the impact of these new drugs in clinical practice. The potential translational mechanisms behind SGLT2i cardio-renal benefits and the information that ongoing studies may add to the already existing body of evidence are also reviewed. Finally, we focus on practical management issues regarding SGLT2i use in association with other T2D and HFrEF common pharmacological therapies. Safety considerations are also highlighted. Considering the paradigm shift in T2D management, from a focus on glycaemic control to a broader approach on cardiovascular protection and event reduction, including the potential for wide SGLT2i implementation in HF patients, with or without T2D, we are facing a promising time for major changes in the global management of cardiovascular disease.
Collapse
Affiliation(s)
- Dulce Brito
- Department of Cardiology, Centro Hospitalar Universitário Lisboa Norte, Av. Prof. Egas Moniz, 1649-035, Lisboa, Portugal. .,CCUL, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-035, Lisboa, Portugal.
| | - Paulo Bettencourt
- Department of Internal Medicine, Hospital CUF Porto, Porto, Portugal.,Faculdade de Medicina, Universidade do Porto, Porto, Portugal
| | - Davide Carvalho
- Faculdade de Medicina, Universidade do Porto, Porto, Portugal.,Department of Endocrinology, Diabetes and Metabolism, Centro Hospitalar, Universitário de São João, Porto, Portugal.,Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Jorge Ferreira
- Department of Cardiology, Hospital de Santa Cruz, Centro Hospitalar de Lisboa Ocidental, Lisbon, Portugal
| | - Ricardo Fontes-Carvalho
- Department of Cardiology, Centro Hospitalar Vila Nova de Gaia/Espinho, Espinho, Portugal.,Department of Surgery and Physiology, Cardiovascular Investigation Unit, Faculdade de Medicina, Universidade do Porto, Porto, Portugal
| | - Fátima Franco
- Department of Cardiology, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal
| | - Brenda Moura
- Faculdade de Medicina, Universidade do Porto, Porto, Portugal.,Department of Cardiology, Hospital das Forças Armadas-Pólo do Porto, Porto, Portugal.,CINTESIS-Cardiocare, Center for Health Technology and Services Research, Porto, Portugal
| | - José Carlos Silva-Cardoso
- Faculdade de Medicina, Universidade do Porto, Porto, Portugal.,CINTESIS-Cardiocare, Center for Health Technology and Services Research, Porto, Portugal.,Department of Cardiology, Centro Hospitalar Universitário de São João, Porto, Portugal
| | | | - Cândida Fonseca
- Heart Failure Clinic, Hospital São Francisco Xavier, Centro Hospitalar de Lisboa Ocidental, Lisboa, Portugal.,NOVA Medical School, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisboa, Portugal
| |
Collapse
|
19
|
An inducible intestinal epithelial cell-specific NHE3 knockout mouse model mimicking congenital sodium diarrhea. Clin Sci (Lond) 2020; 134:941-953. [PMID: 32227118 PMCID: PMC8819665 DOI: 10.1042/cs20200065] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 03/25/2020] [Accepted: 03/27/2020] [Indexed: 12/13/2022]
Abstract
The sodium–hydrogen exchanger isoform 3 (NHE3, SLC9A3) is abundantly expressed in the gastrointestinal tract and is proposed to play essential roles in Na+ and fluid absorption as well as acid–base homeostasis. Mutations in the SLC9A3 gene can cause congenital sodium diarrhea (CSD). However, understanding the precise role of intestinal NHE3 has been severely hampered due to the lack of a suitable animal model. To navigate this problem and better understand the role of intestinal NHE3, we generated a tamoxifen-inducible intestinal epithelial cell-specific NHE3 knockout mouse model (NHE3IEC-KO). Before tamoxifen administration, the phenotype and blood parameters of NHE3IEC-KO were unremarkable compared with control mice. After tamoxifen administration, NHE3IEC-KO mice have undetectable levels of NHE3 in the intestine. NHE3IEC-KO mice develop watery, alkaline diarrhea in combination with a swollen small intestine, cecum and colon. The persistent diarrhea results in higher fluid intake. After 3 weeks, NHE3IEC-KO mice show a ~25% mortality rate. The contribution of intestinal NHE3 to acid–base and Na+ homeostasis under normal conditions becomes evident in NHE3IEC-KO mice that have metabolic acidosis, lower blood bicarbonate levels, hyponatremia and hyperkalemia associated with drastically elevated plasma aldosterone levels. These results demonstrate that intestinal NHE3 has a significant contribution to acid–base, Na+ and volume homeostasis, and lack of intestinal NHE3 has consequences on intestinal structural integrity. This mouse model mimics and explains the phenotype of individuals with CSD carrying SLC9A3 mutations.
Collapse
|
20
|
Chen Y, Wu S, Qi L, Dai W, Tian Y, Kong J. Altered absorptive function in the gall bladder during cholesterol gallstone formation is associated with abnormal NHE3 complex formation. J Physiol Biochem 2020; 76:427-435. [PMID: 32557227 DOI: 10.1007/s13105-020-00751-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 06/04/2020] [Indexed: 02/06/2023]
Abstract
Dysfunction of the Na+/H+ exchanger 3 (NHE3) contributes to the formation of cholesterol gallstones. We aimed to investigate whether NHE3 dysfunction is associated with abnormalities in NHE3 complex formation. We fed C57BL/6 mice with control or lithogenic diet and study the expression of NHE3, ezrin, and Na+/H+ exchanger regulatory factor 1 (NHERF1) in the gallbladder (GB) using RT-PCR and western blot. Immunofluorescence and immunoprecipitation were performed to investigate the interactions of NHE3 with ezrin or NHERF1. To explore the initiating factor that leads to NHE3 dysfunction, we stimulated cholangiocarcinoma cells with taurochenodeoxycholate (TCDC) and/or forskolin. The effects of TCDC on the expression of NHE3 regulatory proteins, as well as their bindings to NHE3, were detected by western blot and immunoprecipitation. Enzyme-linked immunosorbent assay was used to study the regulation of cAMP production by TCDC. The expression of NHERF1 and ezrin phosphorylation level were increased in the gallbladder epithelial cells (GBECs) of C57BL/6 mice with cholesterol gallstones. Immunofluorescence studies demonstrated that the subcellular localization of ezrin and NHERF1 were similar to that of NHE3 in GBECs. Immunoprecipitation revealed that ezrin formed macrocomplex with NHE3, which were enhanced after gallstone formation. TCDC increased forskolin-induced cAMP accumulation, and NHERF1 and PKCα expression in cholangiocarcinoma cells. Under the synergistic effect of forskolin, TCDC stimulated ezrin phosphorylation, with enhanced interaction between ezrin and NHE3. The formation of cholesterol gallstones is associated with abnormal formation of NHE3 complexes. Decreased biliary TCDC may be an initiating factor that leads to abnormal GB absorption.
Collapse
Affiliation(s)
- Yongsheng Chen
- Department of General Surgery, Shengjing Hospital of China Medical University, No. 36, San Hao Street, Heping District, Shenyang, 110004, Liaoning Province, China
| | - Shuodong Wu
- Department of General Surgery, Shengjing Hospital of China Medical University, No. 36, San Hao Street, Heping District, Shenyang, 110004, Liaoning Province, China.
| | - Li Qi
- Department of Rheumatology and Immunology, Shengjing Hospital of China Medical University, No. 39, Hua xiang Road, Tiexi District, Shenyang, 110022, Liaoning Province, China
| | - Wanlin Dai
- China Medical University, No. 77, Pu He Road, Shenbeixin District, Shenyang, 110004, Liaoning Province, China
| | - Yu Tian
- Department of General Surgery, Shengjing Hospital of China Medical University, No. 36, San Hao Street, Heping District, Shenyang, 110004, Liaoning Province, China
| | - Jing Kong
- Department of General Surgery, Shengjing Hospital of China Medical University, No. 36, San Hao Street, Heping District, Shenyang, 110004, Liaoning Province, China
| |
Collapse
|
21
|
Pedersen SF, Counillon L. The SLC9A-C Mammalian Na +/H + Exchanger Family: Molecules, Mechanisms, and Physiology. Physiol Rev 2019; 99:2015-2113. [PMID: 31507243 DOI: 10.1152/physrev.00028.2018] [Citation(s) in RCA: 110] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Na+/H+ exchangers play pivotal roles in the control of cell and tissue pH by mediating the electroneutral exchange of Na+ and H+ across cellular membranes. They belong to an ancient family of highly evolutionarily conserved proteins, and they play essential physiological roles in all phyla. In this review, we focus on the mammalian Na+/H+ exchangers (NHEs), the solute carrier (SLC) 9 family. This family of electroneutral transporters constitutes three branches: SLC9A, -B, and -C. Within these, each isoform exhibits distinct tissue expression profiles, regulation, and physiological roles. Some of these transporters are highly studied, with hundreds of original articles, and some are still only rudimentarily understood. In this review, we present and discuss the pioneering original work as well as the current state-of-the-art research on mammalian NHEs. We aim to provide the reader with a comprehensive view of core knowledge and recent insights into each family member, from gene organization over protein structure and regulation to physiological and pathophysiological roles. Particular attention is given to the integrated physiology of NHEs in the main organ systems. We provide several novel analyses and useful overviews, and we pinpoint main remaining enigmas, which we hope will inspire novel research on these highly versatile proteins.
Collapse
Affiliation(s)
- S F Pedersen
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark; and Université Côte d'Azur, CNRS, Laboratoire de Physiomédecine Moléculaire, LP2M, France, and Laboratories of Excellence Ion Channel Science and Therapeutics, Nice, France
| | - L Counillon
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark; and Université Côte d'Azur, CNRS, Laboratoire de Physiomédecine Moléculaire, LP2M, France, and Laboratories of Excellence Ion Channel Science and Therapeutics, Nice, France
| |
Collapse
|
22
|
Tomilin VN, Pochynyuk O. A peek into Epac physiology in the kidney. Am J Physiol Renal Physiol 2019; 317:F1094-F1097. [PMID: 31509013 DOI: 10.1152/ajprenal.00373.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
cAMP is a critical second messenger of numerous endocrine signals affecting water-electrolyte transport in the renal tubule. Exchange protein directly activated by cAMP (Epac) is a relatively recently discovered downstream effector of cAMP, having the same affinity to the second messenger as protein kinase A, the classical cAMP target. Two Epac isoforms, Epac1 and Epac2, are abundantly expressed in the renal epithelium, where they are thought to regulate water and electrolyte transport, particularly in the proximal tubule and collecting duct. Recent characterization of renal phenotype in mice lacking Epac1 and Epac2 revealed a critical role of the Epac signaling cascade in urinary concentration as well as in Na+ and urea excretion. In this review, we aim to critically summarize current knowledge of Epac relevance for renal function and to discuss the applicability of Epac-based strategies in the regulation of systemic water-electrolyte homeostasis.
Collapse
Affiliation(s)
- Viktor N Tomilin
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas
| | - Oleh Pochynyuk
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas
| |
Collapse
|
23
|
Palaniappan B, Arthur S, Sundaram VL, Butts M, Sundaram S, Mani K, Singh S, Nepal N, Sundaram U. Inhibition of intestinal villus cell Na/K-ATPase mediates altered glucose and NaCl absorption in obesity-associated diabetes and hypertension. FASEB J 2019; 33:9323-9333. [PMID: 31107610 PMCID: PMC6662973 DOI: 10.1096/fj.201802673r] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Accepted: 04/23/2019] [Indexed: 01/07/2023]
Abstract
During obesity, diabetes and hypertension inevitably coexist and cause innumerable health disparities. In the obesity, diabetes, and hypertension triad (ODHT), deregulation of glucose and NaCl homeostasis, respectively, causes diabetes and hypertension. In the mammalian intestine, glucose is primarily absorbed by Na-glucose cotransport 1 (SGLT1) and coupled NaCl by the dual operation of Na-H exchange 3 (NHE3) and Cl-HCO3 [down-regulated in adenoma (DRA) or putative anion transporter 1 (PAT1)] exchange in the brush border membrane (BBM) of villus cells. The basolateral membrane (BLM) Na/K-ATPase provides the favorable transcellular Na gradient for BBM SGLT1 and NHE3. How these multiple, distinct transport processes may be affected in ODHT is unclear. Here, we show the novel and broad regulation by Na/K-ATPase of glucose and NaCl absorption in ODHT in multiple species (mice, rats, and humans). In vivo, during obesity inhibition of villus-cell BLM, Na/K-ATPase led to compensatory stimulation of BBM SGLT1 and DRA or PAT1, whereas NHE3 was unaffected. Supporting this new cellular adaptive mechanism, direct silencing of BLM Na/K-ATPase in intestinal epithelial cells resulted in selective stimulation of BBM SGLT1 and DRA or PAT1 but not NHE3. These changes will lead to an increase in glucose absorption, maintenance of traditional coupled NaCl absorption, and a de novo increase in NaCl absorption from the novel coupling of stimulated SGLT1 with DRA or PAT1. Thus, these novel observations provide the pathophysiologic basis for the deregulation of glucose and NaCl homeostasis of diabetes and hypertension, respectively, during obesity. These observations may lead to more efficacious treatment for obesity-associated diabetes and hypertension.-Palaniappan, B., Arthur, S., Sundaram, V. L., Butts, M., Sundaram, S., Mani, K., Singh, S., Nepal, N., Sundaram, U. Inhibition of intestinal villus cell Na/K-ATPase mediates altered glucose and NaCl absorption in obesity-associated diabetes and hypertension.
Collapse
Affiliation(s)
- Balasubramanian Palaniappan
- Department of Clinical and Translational Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA
| | - Subha Arthur
- Department of Clinical and Translational Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA
| | - Vijaya Lakshmi Sundaram
- Department of Clinical and Translational Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA
| | - Molly Butts
- Department of Clinical and Translational Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA
| | - Shanmuga Sundaram
- Department of Clinical and Translational Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA
| | - Kathiresh Mani
- Department of Clinical and Translational Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA
| | - Soudamani Singh
- Department of Clinical and Translational Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA
| | - Niraj Nepal
- Department of Clinical and Translational Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA
| | - Uma Sundaram
- Department of Clinical and Translational Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, USA
| |
Collapse
|
24
|
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.
Collapse
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
| |
Collapse
|
25
|
Rao MC. Physiology of Electrolyte Transport in the Gut: Implications for Disease. Compr Physiol 2019; 9:947-1023. [PMID: 31187895 DOI: 10.1002/cphy.c180011] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We now have an increased understanding of the genetics, cell biology, and physiology of electrolyte transport processes in the mammalian intestine, due to the availability of sophisticated methodologies ranging from genome wide association studies to CRISPR-CAS technology, stem cell-derived organoids, 3D microscopy, electron cryomicroscopy, single cell RNA sequencing, transgenic methodologies, and tools to manipulate cellular processes at a molecular level. This knowledge has simultaneously underscored the complexity of biological systems and the interdependence of multiple regulatory systems. In addition to the plethora of mammalian neurohumoral factors and their cross talk, advances in pyrosequencing and metagenomic analyses have highlighted the relevance of the microbiome to intestinal regulation. This article provides an overview of our current understanding of electrolyte transport processes in the small and large intestine, their regulation in health and how dysregulation at multiple levels can result in disease. Intestinal electrolyte transport is a balance of ion secretory and ion absorptive processes, all exquisitely dependent on the basolateral Na+ /K+ ATPase; when this balance goes awry, it can result in diarrhea or in constipation. The key transporters involved in secretion are the apical membrane Cl- channels and the basolateral Na+ -K+ -2Cl- cotransporter, NKCC1 and K+ channels. Absorption chiefly involves apical membrane Na+ /H+ exchangers and Cl- /HCO3 - exchangers in the small intestine and proximal colon and Na+ channels in the distal colon. Key examples of our current understanding of infectious, inflammatory, and genetic diarrheal diseases and of constipation are provided. © 2019 American Physiological Society. Compr Physiol 9:947-1023, 2019.
Collapse
Affiliation(s)
- Mrinalini C Rao
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois, USA
| |
Collapse
|
26
|
Cherezova A, Tomilin V, Buncha V, Zaika O, Ortiz PA, Mei F, Cheng X, Mamenko M, Pochynyuk O. Urinary concentrating defect in mice lacking Epac1 or Epac2. FASEB J 2019; 33:2156-2170. [PMID: 30252533 PMCID: PMC6338637 DOI: 10.1096/fj.201800435r] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 08/27/2018] [Indexed: 11/11/2022]
Abstract
cAMP is a universal second messenger regulating a plethora of processes in the kidney. Two downstream effectors of cAMP are PKA and exchange protein directly activated by cAMP (Epac), which, unlike PKA, is often linked to elevation of [Ca2+]i. While both Epac isoforms (Epac1 and Epac2) are expressed along the nephron, their relevance in the kidney remains obscure. We combined ratiometric calcium imaging with quantitative immunoblotting, immunofluorescent confocal microscopy, and balance studies in mice lacking Epac1 or Epac2 to determine the role of Epac in renal water-solute handling. Epac1-/- and Epac2-/- mice developed polyuria despite elevated arginine vasopressin levels. We did not detect major deficiencies in arginine vasopressin [Ca2+]i signaling in split-opened collecting ducts or decreases in aquaporin water channel type 2 levels. Instead, sodium-hydrogen exchanger type 3 levels in the proximal tubule were dramatically reduced in Epac1-/- and Epac2-/- mice. Water deprivation revealed persisting polyuria, impaired urinary concentration ability, and augmented urinary excretion of Na+ and urea in both mutant mice. In summary, we report a nonredundant contribution of Epac isoforms to renal function. Deletion of Epac1 and Epac2 decreases sodium-hydrogen exchanger type 3 expression in the proximal tubule, leading to polyuria and osmotic diuresis.-Cherezova, A., Tomilin, V., Buncha, V., Zaika, O., Ortiz, P. A., Mei, F., Cheng, X., Mamenko, M., Pochynyuk, O. Urinary concentrating defect in mice lacking Epac1 or Epac2.
Collapse
Affiliation(s)
- Alena Cherezova
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Viktor Tomilin
- Department of Integrative Biology and Pharmacology The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Vadym Buncha
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Oleg Zaika
- Department of Integrative Biology and Pharmacology The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Pablo A. Ortiz
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, Detroit, Michigan, USA; and
| | - Fang Mei
- Department of Integrative Biology and Pharmacology The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Xiaodong Cheng
- Department of Integrative Biology and Pharmacology The University of Texas Health Science Center at Houston, Houston, Texas, USA
- Texas Therapeutics Institute, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Mykola Mamenko
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Oleh Pochynyuk
- Department of Integrative Biology and Pharmacology The University of Texas Health Science Center at Houston, Houston, Texas, USA
| |
Collapse
|
27
|
South AM, Shaltout HA, Washburn LK, Hendricks AS, Diz DI, Chappell MC. Fetal programming and the angiotensin-(1-7) axis: a review of the experimental and clinical data. Clin Sci (Lond) 2019; 133:55-74. [PMID: 30622158 PMCID: PMC6716381 DOI: 10.1042/cs20171550] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 11/20/2018] [Accepted: 12/03/2018] [Indexed: 02/07/2023]
Abstract
Hypertension is the primary risk factor for cardiovascular disease that constitutes a serious worldwide health concern and a significant healthcare burden. As the majority of hypertension has an unknown etiology, considerable research efforts in both experimental models and human cohorts has focused on the premise that alterations in the fetal and perinatal environment are key factors in the development of hypertension in children and adults. The exact mechanisms of how fetal programming events increase the risk of hypertension and cardiovascular disease are not fully elaborated; however, the focus on alterations in the biochemical components and functional aspects of the renin-angiotensin (Ang) system (RAS) has predominated, particularly activation of the Ang-converting enzyme (ACE)-Ang II-Ang type 1 receptor (AT1R) axis. The emerging view of alternative pathways within the RAS that may functionally antagonize the Ang II axis raise the possibility that programming events also target the non-classical components of the RAS as an additional mechanism contributing to the development and progression of hypertension. In the current review, we evaluate the potential role of the ACE2-Ang-(1-7)-Mas receptor (MasR) axis of the RAS in fetal programming events and cardiovascular and renal dysfunction. Specifically, the review examines the impact of fetal programming on the Ang-(1-7) axis within the circulation, kidney, and brain such that the loss of Ang-(1-7) expression or tone, contributes to the chronic dysregulation of blood pressure (BP) and cardiometabolic disease in the offspring, as well as the influence of sex on potential programming of this pathway.
Collapse
Affiliation(s)
- Andrew M South
- Department of Pediatrics, Section of Nephrology, Wake Forest School of Medicine, 526 Vine Street, Winston Salem, NC 27157, U.S.A
- Department of Epidemiology and Prevention, Division of Public Health Sciences, Wake Forest School of Medicine, 526 Vine Street, Winston Salem, NC 27157, U.S.A
- Cardiovascular Sciences Center, Wake Forest School of Medicine, 526 Vine Street, Winston Salem, NC 27157, U.S.A
- Hypertension and Vascular Research, Wake Forest School of Medicine, 526 Vine Street, Winston Salem, NC 27157, U.S.A
| | - Hossam A Shaltout
- Cardiovascular Sciences Center, Wake Forest School of Medicine, 526 Vine Street, Winston Salem, NC 27157, U.S.A
- Department of Obstetrics and Gynecology, Wake Forest School of Medicine, 526 Vine Street, Winston Salem, NC 27157, U.S.A
- Department of Pharmacology and Toxicology, School of Pharmacy, University of Alexandria, Egypt
- Hypertension and Vascular Research, Wake Forest School of Medicine, 526 Vine Street, Winston Salem, NC 27157, U.S.A
- Department of Surgery, Wake Forest School of Medicine, 526 Vine Street, Winston Salem, NC 27157, U.S.A
| | - Lisa K Washburn
- Department of Pediatrics, Section of Nephrology, Wake Forest School of Medicine, 526 Vine Street, Winston Salem, NC 27157, U.S.A
- Cardiovascular Sciences Center, Wake Forest School of Medicine, 526 Vine Street, Winston Salem, NC 27157, U.S.A
- Hypertension and Vascular Research, Wake Forest School of Medicine, 526 Vine Street, Winston Salem, NC 27157, U.S.A
| | - Alexa S Hendricks
- Cardiovascular Sciences Center, Wake Forest School of Medicine, 526 Vine Street, Winston Salem, NC 27157, U.S.A
- Hypertension and Vascular Research, Wake Forest School of Medicine, 526 Vine Street, Winston Salem, NC 27157, U.S.A
| | - Debra I Diz
- Cardiovascular Sciences Center, Wake Forest School of Medicine, 526 Vine Street, Winston Salem, NC 27157, U.S.A
- Hypertension and Vascular Research, Wake Forest School of Medicine, 526 Vine Street, Winston Salem, NC 27157, U.S.A
- Department of Surgery, Wake Forest School of Medicine, 526 Vine Street, Winston Salem, NC 27157, U.S.A
| | - Mark C Chappell
- Cardiovascular Sciences Center, Wake Forest School of Medicine, 526 Vine Street, Winston Salem, NC 27157, U.S.A.
- Hypertension and Vascular Research, Wake Forest School of Medicine, 526 Vine Street, Winston Salem, NC 27157, U.S.A
- Department of Surgery, Wake Forest School of Medicine, 526 Vine Street, Winston Salem, NC 27157, U.S.A
| |
Collapse
|
28
|
Ishizuka N, Nakayama M, Watanabe M, Tajima H, Yamauchi Y, Ikari A, Hayashi H. Luminal Na + homeostasis has an important role in intestinal peptide absorption in vivo. Am J Physiol Gastrointest Liver Physiol 2018; 315:G799-G809. [PMID: 30138575 DOI: 10.1152/ajpgi.00099.2018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Intestinal cell line studies indicated luminal Na+ homeostasis is essential for proton-coupled peptide absorption, because the driving force of PepT1 activity is supported by the apical Na+/H+ exchanger NHE3. However, there is no direct evidence demonstrating the importance of in vivo luminal Na+ for peptide absorption in animal experiments. To investigate the relationship between luminal Na+ homeostasis and peptide absorption, we took advantage of claudin 15-deficient (cldn15-/-) mice, whereby Na+ homeostasis is disrupted. We quantitatively assessed the intestinal segment responsible for peptide absorption using radiolabeled nonhydrolyzable dipeptide (glycylsarcosine, Gly-Sar) and nonabsorbable fluid phase marker polyethylene glycol (PEG) 4000 in vivo. In wild-type (WT) mice, the concentration ratio of Gly-Sar to PEG 4000 decreased in the upper jejunum, suggesting the upper jejunum is responsible for peptide absorption. Gly-Sar absorption was decreased in the jejunum of cldn15-/- mice. To elucidate the mechanism underlining these impairments, a Gly-Sar-induced short-circuit ( Isc) current was measured. In WT mice, increments of Gly-Sar-induced Isc were inhibited by the luminal application of a NHE3-specific inhibitor S3226 in a dose-dependent fashion. In contrast to in vivo experiments, robust Gly-Sar-induced Isc increments were observed in the jejunal mucosa of cldn15-/- mice. Gly-Sar-induced Isc was inhibited by S3226 or a reduction of luminal Na+ concentration, which mimics low luminal Na+ concentrations in vivo . Our study demonstrates that luminal Na+ homeostasis is important for peptide absorption in native epithelia and that there is a cooperative functional relationship between PepT1 and NHE3. NEW & NOTEWORTHY Our study is the first to demonstrate that luminal Na+ homeostasis is important for proton-coupled peptide absorption in in vivo animal experiments.
Collapse
Affiliation(s)
- Noriko Ishizuka
- Laboratory of Physiology School of Food and Nutritional Sciences, University of Shizuoka, Suruga-ku, Shizuoka , Japan
| | - Michiko Nakayama
- Laboratory of Physiology School of Food and Nutritional Sciences, University of Shizuoka, Suruga-ku, Shizuoka , Japan
| | - Miki Watanabe
- Laboratory of Physiology School of Food and Nutritional Sciences, University of Shizuoka, Suruga-ku, Shizuoka , Japan
| | - Haruna Tajima
- Laboratory of Physiology School of Food and Nutritional Sciences, University of Shizuoka, Suruga-ku, Shizuoka , Japan
| | - Yuri Yamauchi
- Laboratory of Physiology School of Food and Nutritional Sciences, University of Shizuoka, Suruga-ku, Shizuoka , Japan
| | - Akira Ikari
- Laboratory of Biochemistry, Department of Biopharmaceutical Sciences, Gifu Pharmaceutical University , Gifu , Japan
| | - Hisayoshi Hayashi
- Laboratory of Physiology School of Food and Nutritional Sciences, University of Shizuoka, Suruga-ku, Shizuoka , Japan
| |
Collapse
|
29
|
Packer M. Role of the sodium-hydrogen exchanger in mediating the renal effects of drugs commonly used in the treatment of type 2 diabetes. Diabetes Obes Metab 2018; 20:800-811. [PMID: 29227582 DOI: 10.1111/dom.13191] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 12/07/2017] [Accepted: 12/07/2017] [Indexed: 01/19/2023]
Abstract
Diabetes is characterized by increased activity of the sodium-hydrogen exchanger (NHE) in the glomerulus and renal tubules, which contributes importantly to the development of nephropathy. Despite the established role played by the exchanger in experimental studies, it has not been specifically targeted by those seeking to develop novel pharmacological treatments for diabetes. This review demonstrates that many existing drugs that are commonly prescribed to patients with diabetes act on the NHE1 and NHE3 isoforms in the kidney. This action may explain their effects on sodium excretion, albuminuria and the progressive decline of glomerular function in clinical trials; these responses cannot be readily explained by the influence of these drugs on blood glucose. Agents that may affect the kidney in diabetes by virtue of an action on NHE include: (1) insulin and insulin sensitizers; (2) incretin-based agents; (3) sodium-glucose cotransporter 2 inhibitors; (4) antagonists of the renin-angiotensin system (angiotensin converting-enzyme inhibitors, angiotensin receptor blockers and angiotensin receptor neprilysin inhibitors); and (5) inhibitors of aldosterone action and cholesterol synthesis (spironolactone, amiloride and statins). The renal effects of each of these drug classes in patients with type 2 diabetes may be related to a single shared biological mechanism.
Collapse
Affiliation(s)
- Milton Packer
- Baylor Heart and Vascular Institute, Baylor University Medical Center, Dallas, Texas
| |
Collapse
|
30
|
Xu H, Ghishan FK, Kiela PR. SLC9 Gene Family: Function, Expression, and Regulation. Compr Physiol 2018; 8:555-583. [PMID: 29687889 DOI: 10.1002/cphy.c170027] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The Slc9 family of Na+ /H+ exchangers (NHEs) plays a critical role in electroneutral exchange of Na+ and H+ in the mammalian intestine as well as other absorptive and secretory epithelia of digestive organs. These transport proteins contribute to the transepithelial Na+ and water absorption, intracellular pH and cellular volume regulation as well as the electrolyte, acid-base, and fluid volume homeostasis at the systemic level. They also influence the function of other membrane transport mechanisms, affect cellular proliferation and apoptosis as well as cell migration, adherence to the extracellular matrix, and tissue repair. Additionally, they modulate the extracellular milieu to facilitate other nutrient absorption and to regulate the intestinal microbial microenvironment. Na+ /H+ exchange is inhibited in selected gastrointestinal diseases, either by intrinsic factors (e.g., bile acids, inflammatory mediators) or infectious agents and associated bacterial toxins. Disrupted NHE activity may contribute not only to local and systemic electrolyte imbalance but also to the disease severity via multiple mechanisms. In this review, we describe the cation proton antiporter superfamily of Na+ /H+ exchangers with a particular emphasis on the eight SLC9A isoforms found in the digestive tract, followed by a more integrative description in their roles in each of the digestive organs. We discuss regulatory mechanisms that determine the function of Na+ /H+ exchangers as pertinent to the digestive tract, their regulation in pathological states of the digestive organs, and reciprocally, the contribution of dysregulated Na+ /H+ exchange to the disease pathogenesis and progression. © 2018 American Physiological Society. Compr Physiol 8:555-583, 2018.
Collapse
Affiliation(s)
- Hua Xu
- Department of Pediatrics, Steele Children's Research Center, University of Arizona, Tucson, Arizona, USA
| | - Fayez K Ghishan
- Department of Pediatrics, Steele Children's Research Center, University of Arizona, Tucson, Arizona, USA
| | - Pawel R Kiela
- Department of Pediatrics, Steele Children's Research Center, University of Arizona, Tucson, Arizona, USA.,Department of Immunobiology, University of Arizona, Tucson, Arizona, USA
| |
Collapse
|
31
|
Harris AN, Grimm PR, Lee HW, Delpire E, Fang L, Verlander JW, Welling PA, Weiner ID. Mechanism of Hyperkalemia-Induced Metabolic Acidosis. J Am Soc Nephrol 2018; 29:1411-1425. [PMID: 29483157 DOI: 10.1681/asn.2017111163] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 02/03/2018] [Indexed: 12/22/2022] Open
Abstract
Background Hyperkalemia in association with metabolic acidosis that are out of proportion to changes in glomerular filtration rate defines type 4 renal tubular acidosis (RTA), the most common RTA observed, but the molecular mechanisms underlying the associated metabolic acidosis are incompletely understood. We sought to determine whether hyperkalemia directly causes metabolic acidosis and, if so, the mechanisms through which this occurs.Methods We studied a genetic model of hyperkalemia that results from early distal convoluted tubule (DCT)-specific overexpression of constitutively active Ste20/SPS1-related proline-alanine-rich kinase (DCT-CA-SPAK).Results DCT-CA-SPAK mice developed hyperkalemia in association with metabolic acidosis and suppressed ammonia excretion; however, titratable acid excretion and urine pH were unchanged compared with those in wild-type mice. Abnormal ammonia excretion in DCT-CA-SPAK mice associated with decreased proximal tubule expression of the ammonia-generating enzymes phosphate-dependent glutaminase and phosphoenolpyruvate carboxykinase and overexpression of the ammonia-recycling enzyme glutamine synthetase. These mice also had decreased expression of the ammonia transporter family member Rhcg and decreased apical polarization of H+-ATPase in the inner stripe of the outer medullary collecting duct. Correcting the hyperkalemia by treatment with hydrochlorothiazide corrected the metabolic acidosis, increased ammonia excretion, and normalized ammoniagenic enzyme and Rhcg expression in DCT-CA-SPAK mice. In wild-type mice, induction of hyperkalemia by administration of the epithelial sodium channel blocker benzamil caused hyperkalemia and suppressed ammonia excretion.Conclusions Hyperkalemia decreases proximal tubule ammonia generation and collecting duct ammonia transport, leading to impaired ammonia excretion that causes metabolic acidosis.
Collapse
Affiliation(s)
- Autumn N Harris
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - P Richard Grimm
- Department of Physiology and Maryland Center for Kidney Discovery, University of Maryland School of Medicine, Baltimore, Maryland
| | - Hyun-Wook Lee
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Eric Delpire
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee; and
| | - Lijuan Fang
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Jill W Verlander
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Paul A Welling
- Department of Physiology and Maryland Center for Kidney Discovery, University of Maryland School of Medicine, Baltimore, Maryland
| | - I David Weiner
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida; .,Nephrology and Hypertension Section, Gainesville Veterans Administration Medical Center, Gainesville, Florida
| |
Collapse
|
32
|
Rajkumar P, Cha B, Yin J, Arend LJ, Păunescu TG, Hirabayashi Y, Donowitz M, Pluznick JL. Identifying the localization and exploring a functional role for Gprc5c in the kidney. FASEB J 2018; 32:2046-2059. [PMID: 29196502 DOI: 10.1096/fj.201700610rr] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The investigation of orphan GPCRs (GPRs) has the potential to uncover novel insights into whole animal physiology. In this study, our goal was to determine the renal localization of Gprc5c, a receptor that we previously reported to be highly expressed in murine whole kidney, and to examine physiologic parameters in Gprc5c knockout (KO) mice to gain insight into function. Gprc5c localized to the apical membrane of renal proximal tubules (PTs) in mice, rats, and humans. With the comparison of Gprc5c wild-type (WT) and KO mice, we found that Gprc5c KO mice have altered acid-base homeostasis. Specifically, Gprc5c KO mice have lower blood pH and higher urine pH compared with WT mice, with a reduced level of titratable acids in their urine. In an in vitro GPCR internalization assay, we observed that Gprc5c internalization (an index of activation) was triggered by alkaline extracellular pH. Furthermore, with the use of an in vitro BCECF assay, we observed that Gprc5c increases Na+/H+ exchanger 3 (NHE3) activity at alkaline pH. We also find that the NHE3 activity is reduced in Gprc5c KO mice by 2 photon imaging in seminaphthorhodafluors (SNARF)-4F-loaded kidney sections. NHE3 is a primary contributor to apical transport of H+ in the renal PT. Together, these data imply that Gprc5c modulates the renal contribution to systemic pH homeostasis, at least in part, by taking part in the regulation of NHE3.-Rajkumar, P., Cha, B., Yin, J., Arend, L. J., Păunescu, T. G., Hirabayashi, Y., Donowitz, M., Pluznick, J. L. Identifying the localization and exploring a functional role for Gprc5c in the kidney.
Collapse
Affiliation(s)
- Premraj Rajkumar
- Department of Physiology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Boyoung Cha
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Jianyi Yin
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Lois J Arend
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Teodor G Păunescu
- Division of Nephrology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Yoshio Hirabayashi
- Laboratory for Molecular Membrane Neuroscience, RIKEN Brain Science Institute, Saitama, Japan
| | - Mark Donowitz
- Department of Physiology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Jennifer L Pluznick
- Department of Physiology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| |
Collapse
|
33
|
Engevik AC, Goldenring JR. Trafficking Ion Transporters to the Apical Membrane of Polarized Intestinal Enterocytes. Cold Spring Harb Perspect Biol 2018; 10:cshperspect.a027979. [PMID: 28264818 DOI: 10.1101/cshperspect.a027979] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Epithelial cells lining the gastrointestinal tract require distinct apical and basolateral domains to function properly. Trafficking and insertion of enzymes and transporters into the apical brush border of intestinal epithelial cells is essential for effective digestion and absorption of nutrients. Specific critical ion transporters are delivered to the apical brush border to facilitate fluid and electrolyte uptake. Maintenance of these apical transporters requires both targeted delivery and regulated membrane recycling. Examination of altered apical trafficking in patients with Microvillus Inclusion disease caused by inactivating mutations in MYO5B has led to insights into the regulation of apical trafficking by elements of the apical recycling system. Modeling of MYO5B loss in cell culture and animal models has led to recognition of Rab11a and Rab8a as critical regulators of apical brush border function. All of these studies show the importance of apical membrane trafficking dynamics in maintenance of polarized epithelial cell function.
Collapse
Affiliation(s)
- Amy Christine Engevik
- Section of Surgical Sciences, Vanderbilt University Medical Center, Nashville, Tennessee 37232.,Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, Tennessee 37232
| | - James R Goldenring
- Section of Surgical Sciences, Vanderbilt University Medical Center, Nashville, Tennessee 37232.,Epithelial Biology Center, Vanderbilt University Medical Center, Nashville, Tennessee 37232.,Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee 37232.,Nashville VA Medical Center, Nashville, Tennessee 37232
| |
Collapse
|
34
|
Avula LR, Chen T, Kovbasnjuk O, Donowitz M. Both NHERF3 and NHERF2 are necessary for multiple aspects of acute regulation of NHE3 by elevated Ca 2+, cGMP, and lysophosphatidic acid. Am J Physiol Gastrointest Liver Physiol 2018; 314:G81-G90. [PMID: 28882822 PMCID: PMC5866371 DOI: 10.1152/ajpgi.00140.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The intestinal epithelial brush border Na+/H+ exchanger NHE3 accounts for a large component of intestinal Na absorption. NHE3 is regulated during digestion by signaling complexes on its COOH terminus that include the four multi-PDZ domain-containing NHERF family proteins. All bind to NHE3 and take part in different aspects of NHE3 regulation. Because the roles of each NHERF appear to vary on the basis of the cell model or intestinal segment studied and because of our recent finding that a NHERF3-NHERF2 heterodimer appears important for NHE3 regulation in Caco-2 cells, we examined the role of NHERF3 and NHERF2 in C57BL/6 mouse jejunum using homozygous NHERF2 and NHERF3 knockout mice. NHE3 activity was determined with two-photon microscopy and the dual-emission pH-sensitive dye SNARF-4F. The jejunal apical membrane of NHERF3-null mice appeared similar to wild-type (WT) mice in surface area, microvillus number, and height, which is similar to results previously reported for jejunum of NHERF2-null mice. NHE3 basal activity was not different from WT in either NHERF2- or NHERF3-null jejunum, while d-glucose-stimulated NHE3 activity was reduced in NHERF2, but similar to WT in NHERF3 KO. LPA stimulation and UTP (elevated Ca2+) and cGMP inhibition of NHE3 were markedly reduced in both NHERF2- and NHERF3-null jejunum. Forskolin inhibited NHE3 in NHERF3-null jejunum, but the extent of inhibition was reduced compared with WT. The forskolin inhibition of NHE3 in NHERF2-null mice was too inconsistent to determine whether there was an effect and whether it was altered compared with the WT response. These results demonstrate similar requirement for NHERF2 and NHERF3 in mouse jejunal NHE3 regulation by LPA, Ca2+, and cGMP. The explanation for the similarity is not known but is consistent with involvement of a brush-border NHERF3-NHERF2 heterodimer or sequential NHERF-dependent effects in these aspects of NHE3 regulation. NEW & NOTEWORTHY NHERF2 and NHERF3 are apical membrane multi-PDZ domain-containing proteins that are involved in regulation of intestinal NHE3. This study demonstrates that NHERF2 and NHERF3 have overlapping roles in NHE3 stimulation by LPA and inhibition by elevated Ca2+ and cGMP. These results are consistent with their role being as a NHERF3-NHERF2 heterodimer or via sequential NHERF-dependent signaling steps, and they begin to clarify a role for multiple NHERF proteins in NHE3 regulation.
Collapse
Affiliation(s)
- Leela Rani Avula
- 1Department of Medicine, the Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Tiane Chen
- 1Department of Medicine, the Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Olga Kovbasnjuk
- 1Department of Medicine, the Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Mark Donowitz
- 1Department of Medicine, the Johns Hopkins School of Medicine, Baltimore, Maryland,2Department of Physiology, the Johns Hopkins University School of Medicine, Baltimore, Maryland
| |
Collapse
|
35
|
Wang YY, Chiang HS, Cheng CY, Wu YN, Lin YC, Liu HC, Tsai WK, Chen YL, Lin YH. SLC9A3 Protein Is Critical for Acrosomal Formation in Postmeiotic Male Germ Cells. Int J Mol Sci 2017; 19:ijms19010103. [PMID: 29286340 PMCID: PMC5796053 DOI: 10.3390/ijms19010103] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 12/13/2017] [Accepted: 12/19/2017] [Indexed: 01/07/2023] Open
Abstract
Solute carrier family 9 isoform 3 (SLC9A3), a Na+/H+ exchanger, regulates the transepithelial absorption of Na+ and water and is primarily expressed on the apical membranes of the intestinal epithelium, renal proximal tubule, epididymis, and vas deferens. Loss of the Slc9a3 allele in mice enhances intestinal fluid and causes diarrhoea as a consequence of diminished Na+ and HCO3− absorption. Hence, the loss also causes male infertility and reveals the abnormal dilated lumen of the rete testis and calcification in efferent ductules. However, whether loss of Slc9a3 alleles also disrupts mammalian spermatogenesis remains unknown. First, through immunoblotting, we determined that SLC9A3 is highly expressed in the murine testis compared with the small intestine, epididymis, and vas deferens. During murine spermatogenesis, SLC9A3 is specifically expressed in the acrosome region of round, elongating, and elongated spermatids through immunostaining. Furthermore, SLC9A3 signals are enriched in the acrosome of mature sperm isolated from the vas deferens. In Slc9a3 knockout (KO) mice, compared with the same-aged controls, the number of spermatids on the testicular section of the mice progressively worsened in mice aged 20, 35, and 60 days. Sperm isolated from the epididymis of Slc9a3 KO mice revealed severe acrosomal defects. Our data indicated that SLC9A3 has a vital role in acrosomal formation during spermiogenesis.
Collapse
Affiliation(s)
- Ya-Yun Wang
- Department of Chemistry, Fu Jen Catholic University, New Taipei City 242, Taiwan.
| | - Han-Sun Chiang
- Graduate Institute of Biomedical and Pharmaceutical Science, Fu Jen Catholic University, New Taipei City 242, Taiwan.
| | - Chiao-Yin Cheng
- Graduate Institute of Biomedical and Pharmaceutical Science, Fu Jen Catholic University, New Taipei City 242, Taiwan.
| | - Yi-No Wu
- School of Medicine, Fu Jen Catholic University, New Taipei City 242, Taiwan.
| | - Yung-Chih Lin
- Graduate Institute of Biomedical and Pharmaceutical Science, Fu Jen Catholic University, New Taipei City 242, Taiwan.
| | - Hsuan-Che Liu
- Graduate Institute of Biomedical and Pharmaceutical Science, Fu Jen Catholic University, New Taipei City 242, Taiwan.
| | - Wei-Kung Tsai
- Department of Urology, Mackay Memorial Hospital, Taipei 104, Taiwan.
| | - Yen-Lin Chen
- Department of Chemistry, Fu Jen Catholic University, New Taipei City 242, Taiwan.
- Department of Pathology, Cardinal Tien Hospital, New Taipei City 242, Taiwan.
| | - Ying-Hung Lin
- Graduate Institute of Biomedical and Pharmaceutical Science, Fu Jen Catholic University, New Taipei City 242, Taiwan.
| |
Collapse
|
36
|
Okamoto CT. Regulation of Transporters and Channels by Membrane-Trafficking Complexes in Epithelial Cells. Cold Spring Harb Perspect Biol 2017; 9:a027839. [PMID: 28246186 PMCID: PMC5666629 DOI: 10.1101/cshperspect.a027839] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The vectorial secretion and absorption of fluid and solutes by epithelial cells is dependent on the polarized expression of membrane solute transporters and channels at the apical and basolateral membranes. The establishment and maintenance of this polarized expression of transporters and channels are affected by divers protein-trafficking complexes. Moreover, regulation of the magnitude of transport is often under control of physiological stimuli, again through the interaction of transporters and channels with protein-trafficking complexes. This review highlights the value in utilizing transporters and channels as cargo to characterize core trafficking machinery by which epithelial cells establish and maintain their polarized expression, and how this machinery regulates fluid and solute transport in response to physiological stimuli.
Collapse
Affiliation(s)
- Curtis T Okamoto
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California 90089-9121
| |
Collapse
|
37
|
Packer M. Activation and Inhibition of Sodium-Hydrogen Exchanger Is a Mechanism That Links the Pathophysiology and Treatment of Diabetes Mellitus With That of Heart Failure. Circulation 2017; 136:1548-1559. [PMID: 29038209 DOI: 10.1161/circulationaha.117.030418] [Citation(s) in RCA: 153] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The mechanisms underlying the progression of diabetes mellitus and heart failure are closely intertwined, such that worsening of one condition is frequently accompanied by worsening of the other; the degree of clinical acceleration is marked when the 2 coexist. Activation of the sodium-hydrogen exchanger in the heart and vasculature (NHE1 isoform) and the kidneys (NHE3 isoform) may serve as a common mechanism that links both disorders and may underlie their interplay. Insulin insensitivity and adipokine abnormalities (the hallmarks of type 2 diabetes mellitus) are characteristic features of heart failure; conversely, neurohormonal systems activated in heart failure (norepinephrine, angiotensin II, aldosterone, and neprilysin) impair insulin sensitivity and contribute to microvascular disease in diabetes mellitus. Each of these neurohormonal derangements may act through increased activity of both NHE1 and NHE3. Drugs used to treat diabetes mellitus may favorably affect the pathophysiological mechanisms of heart failure by inhibiting either or both NHE isoforms, and drugs used to treat heart failure may have beneficial effects on glucose tolerance and the complications of diabetes mellitus by interfering with the actions of NHE1 and NHE3. The efficacy of NHE inhibitors on the risk of cardiovascular events may be enhanced when heart failure and glucose intolerance coexist and may be attenuated when drugs with NHE inhibitory actions are given concomitantly. Therefore, the sodium-hydrogen exchanger may play a central role in the interplay of diabetes mellitus and heart failure, contribute to the physiological and clinical progression of both diseases, and explain certain drug-drug and drug-disease interactions that have been reported in large-scale randomized clinical trials.
Collapse
Affiliation(s)
- Milton Packer
- From Baylor Heart and Vascular Institute, Baylor University Medical Center, Dallas, TX.
| |
Collapse
|
38
|
Yin J, Tse CM, Cha B, Sarker R, Zhu XC, Walentinsson A, Greasley PJ, Donowitz M. A common NHE3 single-nucleotide polymorphism has normal function and sensitivity to regulatory ligands. Am J Physiol Gastrointest Liver Physiol 2017; 313:G129-G137. [PMID: 28495802 PMCID: PMC5582881 DOI: 10.1152/ajpgi.00044.2017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 05/01/2017] [Accepted: 05/05/2017] [Indexed: 01/31/2023]
Abstract
Na+/H+ exchanger NHE3 mediates the majority of intestinal and renal electroneutral sodium absorption. Dysfunction of NHE3 is associated with a variety of diarrheal diseases. We previously reported that the NHE3 gene (SLC9A3) has more than 400 single-nucleotide polymorphisms (SNPs) but few nonsynonymous polymorphisms. Among the latter, one polymorphism (rs2247114-G>A), which causes a substitution from arginine to cysteine at amino acid position 799 (p.R799C), is common in Asian populations. To improve our understanding of the population distribution and potential clinical significance of the NHE3-799C variant, we investigated the frequency of this polymorphism in different ethnic groups using bioinformatics analyses and in a cohort of Japanese patients with cardiovascular or renal disease. We also characterized the function of human NHE3-799C and its sensitivity to regulatory ligands in an in vitro model. NHE3-799C had an allele frequency of 29.5-57.6% in Asian populations, 11.1-23.6% in European populations, and 10.2-22.7% in African populations. PS120/FLAG-NHERF2 fibroblasts stably expressing NHE3-799C had lower total protein expression but a higher percentage of surface expression than those expressing NHE3-799R. NHE3-799C had similar basal activity to NHE3-799R and was similarly stimulated or inhibited, by serum or forskolin, respectively. Tenapanor, a small-molecule NHE3 inhibitor, dose-dependently inhibited NHE3-799R and NHE3-799C activities. The IC50 values of tenapanor for NHE3-799C and NHE3-799R were significantly different, but both were in the nanomolar range. These results suggest that NHE3-799C is a common variant enriched in Asian populations, is not associated with compromised function or abnormal regulation, and is unlikely to contribute to clinical disease.NEW & NOTEWORTHY This study reports results on the functional significance of human NHE3-799C under basal conditions and in response to regulatory ligands, including a novel NHE3 inhibitor called tenapanor. We demonstrate that NHE3-799C is a common variant of NHE3 that is enriched in Asian populations; however, in contrast to our previous studies using rabbit NHE3, its presence seems to have limited clinical significance in humans and is not associated with compromised function or abnormal transport regulation.
Collapse
Affiliation(s)
- Jianyi Yin
- 1Department of Medicine, Division of Gastroenterology, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| | - Chung-Ming Tse
- 1Department of Medicine, Division of Gastroenterology, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| | - Boyoung Cha
- 1Department of Medicine, Division of Gastroenterology, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| | - Rafiquel Sarker
- 1Department of Medicine, Division of Gastroenterology, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| | - Xinjun C. Zhu
- 2Department of Medicine, Division of Gastroenterology and Hepatology, Albany Medical College, Albany, New York; and
| | | | | | - Mark Donowitz
- Department of Medicine, Division of Gastroenterology, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| |
Collapse
|
39
|
Sarker R, Cha B, Kovbasnjuk O, Cole R, Gabelli S, Tse CM, Donowitz M. Phosphorylation of NHE3-S 719 regulates NHE3 activity through the formation of multiple signaling complexes. Mol Biol Cell 2017; 28:1754-1767. [PMID: 28495796 PMCID: PMC5491184 DOI: 10.1091/mbc.e16-12-0862] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/09/2017] [Accepted: 05/04/2017] [Indexed: 12/02/2022] Open
Abstract
CK2 regulates NHE3 by phosphorylating a single C-terminal amino acid, which, when mutated, reduces basal NHE3 activity and its acute stimulation and inhibition. It also is necessary for binding of proteins throughout the C-terminus, which means that it determines the C-terminal structure. Casein kinase 2 (CK2) binds to the NHE3 C-terminus and constitutively phosphorylates a downstream site (S719) that accounts for 40% of basal NHE3 activity. The role of CK2 in regulation of NHE3 activity in polarized Caco-2/bbe cells was further examined by mutation of NHE3-S719 to A (not phosphorylated) or D (phosphomimetic). NHE3-S719A but not -S719D had multiple changes in NHE3 activity: 1) reduced basal NHE3 activity—specifically, inhibition of the PI3K/AKT-dependent component; 2) reduced acute stimulation of NHE3 activity by LPA/LPA5R stimulation; and 3) reduced acute inhibition of NHE3 activity—specifically, elevated Ca2+ related (carbachol/Ca2+ ionophore), but there was normal inhibition by forskolin and hyperosmolarity. The S719A mutant had reduced NHE3 complex size, reduced expression in lipid rafts, increased BB mobile fraction, and reduced binding to multiple proteins that bind throughout the NHE3 intracellular C-terminus, including calcineurin homologous protein, the NHERF family and SNX27 (related PDZ domains). These studies show that phosphorylation of the NHE3 at a single amino acid in the distal part of the C-terminus affects multiple aspects of NHE3 complex formation and changes the NHE3 lipid raft distribution, which cause changes in specific aspects of basal as well as acutely stimulated and inhibited Na+/H+ exchange activity.
Collapse
Affiliation(s)
- Rafiquel Sarker
- Department of Physiology and Department of Medicine, GI Division, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Boyoung Cha
- Department of Physiology and Department of Medicine, GI Division, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Olga Kovbasnjuk
- Department of Physiology and Department of Medicine, GI Division, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Robert Cole
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Sandra Gabelli
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Chung Ming Tse
- Department of Physiology and Department of Medicine, GI Division, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Mark Donowitz
- Department of Physiology and Department of Medicine, GI Division, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| |
Collapse
|
40
|
Cha B, Yang J, Singh V, Zachos NC, Sarker RI, Chen TE, Chakraborty M, Tse CM, Donowitz M. PDZ domain-dependent regulation of NHE3 protein by both internal Class II and C-terminal Class I PDZ-binding motifs. J Biol Chem 2017; 292:8279-8290. [PMID: 28283572 DOI: 10.1074/jbc.m116.774489] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 03/06/2017] [Indexed: 12/16/2022] Open
Abstract
NHE3 directly binds Na+/H+ exchanger regulatory factor (NHERF) family scaffolding proteins that are required for many aspects of NHE3 regulation. The NHERFs bind both to an internal region (amino acids 586-660) of the NHE3 C terminus and to the NHE3 C-terminal four amino acids. The internal NHERF-binding region contains both putative Class I (-592SAV-) and Class II (-595CLDM-) PDZ-binding motifs (PBMs). Point mutagenesis showed that only the Class II motif contributes to NHERF binding. In this study, the roles in regulation of NHE3 activity of these two PBMs were investigated, revealing the following findings. 1) Interaction occurred between these binding sites because mutation of either removed nearly all NHERF binding. 2) Mutations in either significantly reduced basal NHE3 activity. Total and percent plasma membrane (PM) NHE3 protein expression was reduced in the C-terminal but not in the internal PBD mutation. 3) cGMP- and Ca2+-mediated inhibition of NHE3 was impaired in both the internal and the C-terminal PBM mutations. 4) There was a significant reduction in half-life of the PM pool of NHE3 in only the internal PBM mutation but no change in total NHE3 half-life in either. 5) There were some differences in NHE3-associating proteins in the two PBM mutations. In conclusion, NHE3 binds to NHERF proteins via both an internal Class II PBM and C-terminal Class I PBM, which interact. The former determines NHE3 stability in the PM, and the latter determines total expression and percent PM expression.
Collapse
Affiliation(s)
- Boyoung Cha
- Departments of Physiology and Medicine, Gastroenterology Division, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Jianbo Yang
- Departments of Physiology and Medicine, Gastroenterology Division, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Varsha Singh
- Departments of Physiology and Medicine, Gastroenterology Division, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Nicholas C Zachos
- Departments of Physiology and Medicine, Gastroenterology Division, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Rafiquel I Sarker
- Departments of Physiology and Medicine, Gastroenterology Division, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Tian-E Chen
- Departments of Physiology and Medicine, Gastroenterology Division, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Molee Chakraborty
- Departments of Physiology and Medicine, Gastroenterology Division, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Chung-Ming Tse
- Departments of Physiology and Medicine, Gastroenterology Division, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Mark Donowitz
- Departments of Physiology and Medicine, Gastroenterology Division, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
| |
Collapse
|
41
|
Paehler Vor der Nolte A, Chodisetti G, Yuan Z, Busch F, Riederer B, Luo M, Yu Y, Menon MB, Schneider A, Stripecke R, Nikolovska K, Yeruva S, Seidler U. Na + /H + exchanger NHE1 and NHE2 have opposite effects on migration velocity in rat gastric surface cells. J Cell Physiol 2017; 232:1669-1680. [PMID: 28019659 PMCID: PMC5396337 DOI: 10.1002/jcp.25758] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 12/21/2016] [Accepted: 12/22/2016] [Indexed: 12/13/2022]
Abstract
Following superficial injury, neighbouring gastric epithelial cells close the wound by rapid cell migration, a process called epithelial restitution. Na+/H+ exchange (NHE) inhibitors interfere with restitution, but the role of the different NHE isoforms expressed in gastric pit cells has remained elusive. The role of the basolaterally expressed NHE1 (Slc9a1) and the presumably apically expressed NHE2 (Slc9a2) in epithelial restitution was investigated in the nontransformed rat gastric surface cell line RGM1. Migration velocity was assessed by loading the cells with the fluorescent dye DiR and following closure of an experimental wound over time. Since RGM1 cells expressed very low NHE2 mRNA and have low transport activity, NHE2 was introduced by lentiviral gene transfer. In medium with pH 7.4, RGM1 cells displayed slow wound healing even in the absence of growth factors and independently of NHE activity. Growth factors accelerated wound healing in a partly NHE1‐dependent fashion. Preincubation with acidic pH 7.1 stimulated restitution in a NHE1‐dependent fashion. When pH 7.1 was maintained during the restitution period, migratory speed was reduced to ∼10% of the speed at pH 7,4, and the residual restitution was further inhibited by NHE1 inhibition. Lentiviral NHE2 expression increased the steady‐state pHi and reduced the restitution velocity after low pH preincubation, which was reversible by pharmacological NHE2 inhibition. The results demonstrate that in RGM1 cells, migratory velocity is increased by NHE1 activation, while NHE2 activity inhibit this process. A differential activation of NHE1 and NHE2 may therefore, play a role in the initiation and completion of the epithelial restitution process.
Collapse
Affiliation(s)
- Anja Paehler Vor der Nolte
- Departments of Gastroenterology, Hemostatsis, Oncology and Stem Cell Transplantation, Medical School of Hannover, Germany
| | - Giriprakash Chodisetti
- Departments of Gastroenterology, Hemostatsis, Oncology and Stem Cell Transplantation, Medical School of Hannover, Germany
| | - Zhenglin Yuan
- Departments of Gastroenterology, Hemostatsis, Oncology and Stem Cell Transplantation, Medical School of Hannover, Germany
| | - Florian Busch
- Departments of Gastroenterology, Hemostatsis, Oncology and Stem Cell Transplantation, Medical School of Hannover, Germany
| | - Brigitte Riederer
- Departments of Gastroenterology, Hemostatsis, Oncology and Stem Cell Transplantation, Medical School of Hannover, Germany
| | - Min Luo
- Departments of Gastroenterology, Hemostatsis, Oncology and Stem Cell Transplantation, Medical School of Hannover, Germany
| | - Yan Yu
- Departments of Gastroenterology, Hemostatsis, Oncology and Stem Cell Transplantation, Medical School of Hannover, Germany
| | - Manoj B Menon
- Departments of Biochemistry, Hemostatsis, Oncology and Stem Cell Transplantation, Medical School of Hannover, Germany
| | - Andreas Schneider
- Departments of Hematology, Hemostatsis, Oncology and Stem Cell Transplantation, Medical School of Hannover, Germany
| | - Renata Stripecke
- Departments of Hematology, Hemostatsis, Oncology and Stem Cell Transplantation, Medical School of Hannover, Germany
| | - Katerina Nikolovska
- Departments of Gastroenterology, Hemostatsis, Oncology and Stem Cell Transplantation, Medical School of Hannover, Germany
| | - Sunil Yeruva
- Departments of Gastroenterology, Hemostatsis, Oncology and Stem Cell Transplantation, Medical School of Hannover, Germany
| | - Ursula Seidler
- Departments of Gastroenterology, Hemostatsis, Oncology and Stem Cell Transplantation, Medical School of Hannover, Germany
| |
Collapse
|
42
|
Charoenphandhu N, Kraidith K, Lertsuwan K, Sripong C, Suntornsaratoon P, Svasti S, Krishnamra N, Wongdee K. Na +/H + exchanger 3 inhibitor diminishes hepcidin-enhanced duodenal calcium transport in hemizygous β-globin knockout thalassemic mice. Mol Cell Biochem 2016; 427:201-208. [PMID: 27995414 DOI: 10.1007/s11010-016-2911-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 12/03/2016] [Indexed: 12/15/2022]
Abstract
Recent investigation has shown that the liver-derived iron-regulating hormone, hepcidin, can potentiate intestinal calcium absorption in hemizygous β-globin knockout thalassemic (BKO) mice. Since the upregulation of Fe2+ and H+ cotransporter, divalent metal transporter (DMT)-1, has been shown to correlate with thalassemia-induced intestinal calcium absorption impairment, the inhibition of the apical Na+/H+ exchanger (NHE)-3 that is essential for cytoplasmic pH regulation and transepithelial sodium absorption was hypothesized to negatively affect hepcidin action. Herein, the positive effect of hepcidin on the duodenal calcium transport was evaluated using Ussing chamber technique. The results showed that BKO mice had lower absorptive surface area and duodenal calcium transport than wild-type mice. Besides, paracellular transport of zinc in BKO mice was compromised. Hepcidin administration completely restored calcium transport. Since this hepcidin action was totally abolished by inhibitors of the basolateral calcium transporters, Na+/Ca2+ exchanger (NCX1) and plasma membrane Ca2+-ATPase (PMCA1b), the enhanced calcium flux potentially occurred through the transcellular pathway rather than paracellular pathway. Interestingly, the selective NHE3 inhibitor, 100 nM tenapanor, markedly inhibited hepcidin-enhanced calcium transport. Accordingly, hepcidin is one of the promising therapeutic agents for calcium malabsorption in β-thalassemia. It mainly stimulates the transcellular calcium transport across the duodenal epithelium in an NHE3-dependent manner.
Collapse
Affiliation(s)
- Narattaphol Charoenphandhu
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand.,Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand.,Institute of Molecular Biosciences, Mahidol University, Salaya, Nakhon Pathom, Thailand
| | - Kamonshanok Kraidith
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand.,Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Kornkamon Lertsuwan
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand.,Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Chanakarn Sripong
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand.,Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Panan Suntornsaratoon
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand.,Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Saovaros Svasti
- Thalassemia Research Center, Institute of Molecular Biosciences, Mahidol University, Salaya, Nakhon Pathom, Thailand
| | - Nateetip Krishnamra
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand.,Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Kannikar Wongdee
- Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University, Bangkok, Thailand. .,Office of Academic Management, Faculty of Allied Health Sciences, Burapha University, Chonburi, Thailand.
| |
Collapse
|
43
|
Abstract
Several members of the SLC9A family of Na+/H+ exchangers are expressed in the gut, with varying expression patterns and cellular localization. Not only do they participate in the regulation of basic epithelial cell functions, including control of transepithelial Na+ absorption, intracellular pH (pH i ), cell volume, and nutrient absorption, but also in cellular proliferation, migration, and apoptosis. Additionally, they modulate the extracellular milieu in order to facilitate other nutrient absorption and to regulate the intestinal microbial microenvironment. Na+/H+ exchangers are frequent targets of inhibition in gastrointestinal pathologies, either by intrinsic factors (e.g. bile acids, inflammatory mediators) or infectious agents and associated microbial toxins. Based on emerging evidence, disruption of NHE activity via impaired expression or function of respective isoforms may contribute not only to local and systemic electrolyte imbalance, but also to the disease severity via multiple mechanisms. Here, we review the current state of knowledge about the roles Na+/H+ exchangers play in the pathogenesis of disorders of diverse origin and affecting a range of GI tissues.
Collapse
Affiliation(s)
- Michael A. Gurney
- Department of Pediatrics, Steele Children’s Research Center, University of Arizona, Tucson, Arizona
| | - Daniel Laubitz
- Department of Pediatrics, Steele Children’s Research Center, University of Arizona, Tucson, Arizona
| | - Fayez K. Ghishan
- Department of Pediatrics, Steele Children’s Research Center, University of Arizona, Tucson, Arizona
| | - Pawel R. Kiela
- Department of Pediatrics, Steele Children’s Research Center, University of Arizona, Tucson, Arizona,Department of Immunobiology, University of Arizona, Tucson, Arizona,Correspondence Address correspondence to: Pawel R. Kiela, DVM, PhD, Department of Pediatrics, University of Arizona, 1501 North Campbell Avenue, Tucson, Arizona 85724. fax: (520) 626-4141.Department of Pediatrics, University of Arizona1501 North Campbell AvenueTucsonArizona 85724
| |
Collapse
|
44
|
Müller T, Rasool I, Heinz-Erian P, Mildenberger E, Hülstrunk C, Müller A, Michaud L, Koot BGP, Ballauff A, Vodopiutz J, Rosipal S, Petersen BS, Franke A, Fuchs I, Witt H, Zoller H, Janecke AR, Visweswariah SS. Congenital secretory diarrhoea caused by activating germline mutations in GUCY2C. Gut 2016; 65:1306-13. [PMID: 25994218 PMCID: PMC4975829 DOI: 10.1136/gutjnl-2015-309441] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2015] [Accepted: 04/10/2015] [Indexed: 01/08/2023]
Abstract
OBJECTIVE Congenital sodium diarrhoea (CSD) refers to a form of secretory diarrhoea with intrauterine onset and high faecal losses of sodium without congenital malformations. The molecular basis for CSD remains unknown. We clinically characterised a cohort of infants with CSD and set out to identify disease-causing mutations by genome-wide genetic testing. DESIGN We performed whole-exome sequencing and chromosomal microarray analyses in 4 unrelated patients, followed by confirmatory Sanger sequencing of the likely disease-causing mutations in patients and in their family members, followed by functional studies. RESULTS We identified novel de novo missense mutations in GUCY2C, the gene encoding receptor guanylate cyclase C (GC-C) in 4 patients with CSD. One patient developed severe, early-onset IBD and chronic arthritis at 4 years of age. GC-C is an intestinal brush border membrane-bound guanylate cyclase, which functions as receptor for guanylin, uroguanylin and Escherichia coli heat-stable enterotoxin. Mutations in GUCY2C were present in different intracellular domains of GC-C, and were activating mutations that enhanced intracellular cyclic guanosine monophosphate accumulation in a ligand-independent and ligand-stimulated manner, following heterologous expression in HEK293T cells. CONCLUSIONS Dominant gain-of-function GUCY2C mutations lead to elevated intracellular cyclic guanosine monophosphate levels and could explain the chronic diarrhoea as a result of decreased intestinal sodium and water absorption and increased chloride secretion. Thus, mutations in GUCY2C indicate a role for this receptor in the pathogenesis of sporadic CSD.
Collapse
Affiliation(s)
- Thomas Müller
- Department of Pediatrics I, Medical University of Innsbruck, Innsbruck, Austria
| | - Insha Rasool
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, India
| | - Peter Heinz-Erian
- Department of Pediatrics I, Medical University of Innsbruck, Innsbruck, Austria
| | - Eva Mildenberger
- Department of Neonatology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Christian Hülstrunk
- Department of Neonatology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | | | - Laurent Michaud
- Clinique de Pédiatrie, Pôle enfant, Hôpital J de Flandre CHRU de Lille, Inserm U995, Faculté de Médecine, Université de Lille 2, Lille, France
| | - Bart G P Koot
- Department of Pediatrics, Academic Medical Center, Amsterdam, The Netherlands
| | | | - Julia Vodopiutz
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria
| | - Stefan Rosipal
- Pediatric Clinic of Preventive Medicine in Poprad, Slovak Health University, Poprad,Slovakia
| | - Britt-Sabina Petersen
- Institute of Clinical Molecular Biology, Christian-Albrechts-University Kiel, Kiel, Germany
| | - Andre Franke
- Institute of Clinical Molecular Biology, Christian-Albrechts-University Kiel, Kiel, Germany
| | - Irene Fuchs
- Department of Pediatrics I, Medical University of Innsbruck, Innsbruck, Austria
| | - Heiko Witt
- Pädiatrische Ernährungsmedizin, Else Kröner-Fresenius-Zentrum (EKFZ) für Ernährungsmedizin, Technische Universität München (TUM), Freising-Weihenstephan, Germany
| | - Heinz Zoller
- Department of Internal Medicine, Medical University of Innsbruck, Innsbruck, Austria
| | - Andreas R Janecke
- Department of Pediatrics I, Medical University of Innsbruck, Innsbruck, Austria
| | - Sandhya S Visweswariah
- Department of Neonatology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| |
Collapse
|
45
|
Congenital Sodium Diarrhea: A Form of Intractable Diarrhea, With a Link to Inflammatory Bowel Disease. J Pediatr Gastroenterol Nutr 2016; 63:170-6. [PMID: 26835907 DOI: 10.1097/mpg.0000000000001139] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Congenital diarrheal disorders (CDDs) represent a group of challenging clinical conditions for pediatricians because of the severity of the presentation and the broad range of possible differential diagnoses. CDDs arise from alterations in the transport of nutrients and electrolytes across the intestinal mucosa, from enterocyte and enteroendocrine cell differentiation and/or polarization defects, and from the modulation of the intestinal immune response. Advances were made recently in deciphering the etiology and pathophysiology of one of these disorders, congenital sodium diarrhea (CSD). CSD refers to an intractable diarrhea of intrauterine onset with high fecal sodium loss. CSD is clinically and genetically heterogeneous. A syndromic form of CSD features choanal and intestinal atresias as well as recurrent corneal erosions. Small bowel histology frequently detects an epithelial "tufting" dysplasia. It is autosomal recessively inherited, and caused by SPINT2 mutations. The nonsyndromic form of CSD can be caused by dominant activating mutations in GUCY2C, encoding intestinal receptor guanylate cyclase C (GC-C), and by autosomal recessive SLC9A3 loss-of-function mutations. SLC9A3 encodes Na/H antiporter 3, the major intestinal brush border Na/H exchanger, and a downstream target of GC-C. A number of patients with GUCY2C and SLC9A3 mutations developed inflammatory bowel disease. Both the number of recognized CDD forms as well as the number of underlying disease genes are gradually increasing. Knowledge of these CDD genes enables noninvasive, next-generation gene panel-based testing to facilitate an early diagnosis in CDD. Primary Na/H antiporter 3 and GC-C malfunction is implicated as a predisposition for inflammatory bowel disease in subset of patients.
Collapse
|
46
|
Coady MJ, El Tarazi A, Santer R, Bissonnette P, Sasseville LJ, Calado J, Lussier Y, Dumayne C, Bichet DG, Lapointe JY. MAP17 Is a Necessary Activator of Renal Na+/Glucose Cotransporter SGLT2. J Am Soc Nephrol 2016; 28:85-93. [PMID: 27288013 DOI: 10.1681/asn.2015111282] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 04/05/2016] [Indexed: 11/03/2022] Open
Abstract
The renal proximal tubule reabsorbs 90% of the filtered glucose load through the Na+-coupled glucose transporter SGLT2, and specific inhibitors of SGLT2 are now available to patients with diabetes to increase urinary glucose excretion. Using expression cloning, we identified an accessory protein, 17 kDa membrane-associated protein (MAP17), that increased SGLT2 activity in RNA-injected Xenopus oocytes by two orders of magnitude. Significant stimulation of SGLT2 activity also occurred in opossum kidney cells cotransfected with SGLT2 and MAP17. Notably, transfection with MAP17 did not change the quantity of SGLT2 protein at the cell surface in either cell type. To confirm the physiologic relevance of the MAP17-SGLT2 interaction, we studied a cohort of 60 individuals with familial renal glucosuria. One patient without any identifiable mutation in the SGLT2 coding gene (SLC5A2) displayed homozygosity for a splicing mutation (c.176+1G>A) in the MAP17 coding gene (PDZK1IP1). In the proximal tubule and in other tissues, MAP17 is known to interact with PDZK1, a scaffolding protein linked to other transporters, including Na+/H+ exchanger 3, and to signaling pathways, such as the A-kinase anchor protein 2/protein kinase A pathway. Thus, these results provide the basis for a more thorough characterization of SGLT2 which would include the possible effects of its inhibition on colocalized renal transporters.
Collapse
Affiliation(s)
- Michael J Coady
- Physics Department & Groupe d'étude des protéines membranaires
| | - Abdulah El Tarazi
- Departement of Molecular and Integrative Physiology & Groupe d'étude des protéines membranaires, and
| | - René Santer
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; and
| | - Pierre Bissonnette
- Departement of Molecular and Integrative Physiology & Groupe d'étude des protéines membranaires, and
| | | | - Joaquim Calado
- Department of Nephrology, ToxOmics, Centre for Toxicogenomics and Human Health, NOVA Medical School, New University of Lisbon, Lisbon, Portugal
| | - Yoann Lussier
- Departement of Molecular and Integrative Physiology & Groupe d'étude des protéines membranaires, and
| | - Christopher Dumayne
- Departement of Molecular and Integrative Physiology & Groupe d'étude des protéines membranaires, and
| | - Daniel G Bichet
- Departement of Molecular and Integrative Physiology & Groupe d'étude des protéines membranaires, and.,Department of Medicine, Centre de recherche de l'Hôpital du Sacré-Cœur, University of Montreal, Montreal, Quebec, Canada
| | | |
Collapse
|
47
|
Yang L, Faraone SV, Zhang-James Y. Autism spectrum disorder traits in Slc9a9 knock-out mice. Am J Med Genet B Neuropsychiatr Genet 2016; 171B:363-76. [PMID: 26755066 DOI: 10.1002/ajmg.b.32415] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 12/22/2015] [Indexed: 11/09/2022]
Abstract
Autism spectrum disorders (ASDs) are a group of neurodevelopmental disorders which begin in childhood and persist into adulthood. They cause lifelong impairments and are associated with substantial burdens to patients, families, and society. Genetic studies have implicated the sodium/proton exchanger (NHE) nine gene, Slc9a9, to ASDs and attention-deficit/hyperactivity disorder(ADHD). Slc9a9 encodes, NHE9, a membrane protein of the late recycling endosomes. The recycling endosome plays an important role in synapse development and plasticity by regulating the trafficking of membrane neurotransmitter receptors and transporters. Here we tested the hypothesis that Slc9a9 knock-out (KO) mice would show ADHD-like and ASD-like traits. Ultrasonic vocalization (USV) recording showed that Slc9a9 KO mice emitted fewer calls and had shorter call durations, which suggest communication impairment. Slc9a9 KO mice lacked a preference for social novelty, but did not show deficits in social approach; Slc9a9 KO mice spent more time self-grooming, an indicator for restricted and repetitive behavior. We did not observe hyperactivity or other behavior impairments which are commonly comorbid with ASDs in human, such as anxiety-like behavior. Our study is the first animal behavior study that links Slc9a9 to ASDs. By eliminatingNHE9 activity, it provides strong evidence that lack of Slc9a9leads to ASD-like behaviors in mice and provides the field with a new mouse model of ASDs.
Collapse
Affiliation(s)
- Lina Yang
- Departments of Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, New York
| | - Stephen V Faraone
- Departments of Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, New York.,Departments of Psychiatry, SUNY Upstate Medical University, Syracuse, New York.,K.G. Jebsen Centre for Research on Neuropsychiatric Disorders, University of Bergen, Bergen, Norway
| | - Yanli Zhang-James
- Departments of Psychiatry, SUNY Upstate Medical University, Syracuse, New York
| |
Collapse
|
48
|
Sodium-Proton (Na+/H+) Antiporters: Properties and Roles in Health and Disease. Met Ions Life Sci 2016; 16:391-458. [DOI: 10.1007/978-3-319-21756-7_12] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
|
49
|
Allman E, Wang Q, Walker RL, Austen M, Peters MA, Nehrke K. Calcineurin homologous proteins regulate the membrane localization and activity of sodium/proton exchangers in C. elegans. Am J Physiol Cell Physiol 2015; 310:C233-42. [PMID: 26561640 DOI: 10.1152/ajpcell.00291.2015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 11/09/2015] [Indexed: 11/22/2022]
Abstract
Calcineurin B homologous proteins (CHP) are N-myristoylated, EF-hand Ca(2+)-binding proteins that bind to and regulate Na(+)/H(+) exchangers, which occurs through a variety of mechanisms whose relative significance is incompletely understood. Like mammals, Caenorhabditis elegans has three CHP paralogs, but unlike mammals, worms can survive CHP loss-of-function. However, mutants for the CHP ortholog PBO-1 are unfit, and PBO-1 has been shown to be required for proton signaling by the basolateral Na(+)/H(+) exchanger NHX-7 and for proton-coupled intestinal nutrient uptake by the apical Na(+)/H(+) exchanger NHX-2. Here, we have used this genetic model organism to interrogate PBO-1's mechanism of action. Using fluorescent tags to monitor Na(+)/H(+) exchanger trafficking and localization, we found that loss of either PBO-1 binding or activity caused NHX-7 to accumulate in late endosomes/lysosomes. In contrast, NHX-2 was stabilized at the apical membrane by a nonfunctional PBO-1 protein and was only internalized following its complete loss. Additionally, two pbo-1 paralogs were identified, and their expression patterns were analyzed. One of these contributed to the function of the excretory cell, which acts like a kidney in worms, establishing an alternative model for testing the role of this protein in membrane transporter trafficking and regulation. These results lead us to conclude that the role of CHP in Na(+)/H(+) exchanger regulation differs between apical and basolateral transporters. This further emphasizes the importance of proper targeting of Na(+)/H(+) exchangers and the critical role of CHP family proteins in this process.
Collapse
Affiliation(s)
- Erik Allman
- Departments of Pharmacology and Physiology and Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York; Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania
| | - Qian Wang
- Departments of Pharmacology and Physiology and Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York
| | - Rachel L Walker
- Departments of Pharmacology and Physiology and Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York
| | - Molly Austen
- Departments of Pharmacology and Physiology and Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York
| | | | - Keith Nehrke
- Departments of Pharmacology and Physiology and Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York;
| |
Collapse
|
50
|
Janecke AR, Heinz-Erian P, Yin J, Petersen BS, Franke A, Lechner S, Fuchs I, Melancon S, Uhlig HH, Travis S, Marinier E, Perisic V, Ristic N, Gerner P, Booth IW, Wedenoja S, Baumgartner N, Vodopiutz J, Frechette-Duval MC, De Lafollie J, Persad R, Warner N, Tse CM, Sud K, Zachos NC, Sarker R, Zhu X, Muise AM, Zimmer KP, Witt H, Zoller H, Donowitz M, Müller T. Reduced sodium/proton exchanger NHE3 activity causes congenital sodium diarrhea. Hum Mol Genet 2015; 24:6614-23. [PMID: 26358773 DOI: 10.1093/hmg/ddv367] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 09/03/2015] [Indexed: 02/06/2023] Open
Abstract
Congenital sodium diarrhea (CSD) refers to an intractable diarrhea of intrauterine onset with high fecal sodium loss. CSD is clinically and genetically heterogeneous. Syndromic CSD is caused by SPINT2 mutations. While we recently described four cases of the non-syndromic form of CSD that were caused by dominant activating mutations in intestinal receptor guanylate cyclase C (GC-C), the genetic cause for the majority of CSD is still unknown. Therefore, we aimed to determine the genetic cause for non-GC-C non-syndromic CSD in 18 patients from 16 unrelated families applying whole-exome sequencing and/or chromosomal microarray analyses and/or direct Sanger sequencing. SLC9A3 missense, splicing and truncation mutations, including an instance of uniparental disomy, and whole-gene deletion were identified in nine patients from eight families with CSD. Two of these nine patients developed inflammatory bowel disease (IBD) at 4 and 16 years of age. SLC9A3 encodes Na(+)/H(+) antiporter 3 (NHE3), which is the major intestinal brush-border Na(+)/H(+) exchanger. All mutations were in the NHE3 N-terminal transport domain, and all missense mutations were in the putative membrane-spanning domains. Identified SLC9A3 missense mutations were functionally characterized in plasma membrane NHE null fibroblasts. SLC9A3 missense mutations compromised NHE3 activity by reducing basal surface expression and/or loss of basal transport function of NHE3 molecules, whereas acute regulation was normal. This study identifies recessive mutations in NHE3, a downstream target of GC-C, as a cause of CSD and implies primary basal NHE3 malfunction as a predisposition for IBD in a subset of patients.
Collapse
Affiliation(s)
| | | | - Jianyi Yin
- Department of Medicine, Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Britt-Sabina Petersen
- Institute of Clinical Molecular Biology, Christian-Albrechts-University, Kiel 24105, Germany
| | - Andre Franke
- Institute of Clinical Molecular Biology, Christian-Albrechts-University, Kiel 24105, Germany
| | | | | | - Serge Melancon
- Department of Medical Genetics, McGill University Health Centre, Montreal, Canada H3H 1P3
| | - Holm H Uhlig
- Translational Gastroenterology Unit, Nuffield Department of Medicine, and Children's Hospital, University of Oxford, Oxford OX3 9DU, UK
| | - Simon Travis
- Translational Gastroenterology Unit, Nuffield Department of Medicine, and Children's Hospital, University of Oxford, Oxford OX3 9DU, UK
| | - Evelyne Marinier
- Service des maladies digestives et respiratoires de l'enfant, Centre de référence des maladies digestives rares, Hôpital R Debré, Paris 75935, France
| | - Vojislav Perisic
- Department of Hepatology and GI Endoscopy, University Children's Hospital, Belgrade 11000, Serbia
| | - Nina Ristic
- Department of Hepatology and GI Endoscopy, University Children's Hospital, Belgrade 11000, Serbia
| | - Patrick Gerner
- Zentrum für Kinder-und Jugendmedizin, Universitätsklinikum, Freiburg 79106, Germany
| | - Ian W Booth
- Paediatrics and Child Health, University of Birmingham, Birmingham B4 6NH, UK
| | - Satu Wedenoja
- Department of Medical Genetics, University of Helsinki, Helsinki 00014, Finland
| | - Nadja Baumgartner
- Department of Internal Medicine, Medical University of Innsbruck, Innsbruck 6020, Austria
| | - Julia Vodopiutz
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Wien 1090, Austria
| | | | - Jan De Lafollie
- Abteilung Allgemeine Pädiatrie & Neonatologie, Zentrum für Kinderheilkunde und Jugendmedizin, Justus-Liebig-Universität, Gießen 35392, Germany
| | - Rabindranath Persad
- Stollery Children's Hospital, University of Alberta, Edmonton, Canada T6G 2B7
| | - Neil Warner
- SickKids Inflammatory Bowel Disease Center and Cell Biology Program, Research Institute, Hospital for Sick Children, Toronto, ON, Canada M5G 1X8
| | - C Ming Tse
- Department of Medicine, Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Karan Sud
- Department of Medicine, Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Nicholas C Zachos
- Department of Medicine, Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Rafiquel Sarker
- Department of Medicine, Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Xinjun Zhu
- Department of Medicine, Albany Medical Center, Albany, NY 12208, USA
| | - Aleixo M Muise
- SickKids Inflammatory Bowel Disease Center and Cell Biology Program, Research Institute, Hospital for Sick Children, Toronto, ON, Canada M5G 1X8, Department of Biochemistry, Department of IMS, Department of Pediatrics, Division of Gastroenterology, Hepatology, and Nutrition, University of Toronto, Toronto, ON, Canada M5G 1X8 and
| | - Klaus-Peter Zimmer
- Abteilung Allgemeine Pädiatrie & Neonatologie, Zentrum für Kinderheilkunde und Jugendmedizin, Justus-Liebig-Universität, Gießen 35392, Germany
| | - Heiko Witt
- Pädiatrische Ernährungsmedizin, Else Kröner-Fresenius-Zentrum für Ernährungsmedizin, Technische Universität München, Freising-Weihenstephan 85350, Germany
| | - Heinz Zoller
- Department of Internal Medicine, Medical University of Innsbruck, Innsbruck 6020, Austria
| | - Mark Donowitz
- Department of Medicine, Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | | |
Collapse
|