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Luo M, Liu Y, Nikolovska K, Riederer B, Patrucco E, Hofmann F, Seidler U. cGMP-dependent kinase 2, Na +/H + exchanger NHE3, and PDZ-adaptor NHERF2 co-assemble in apical membrane microdomains. Acta Physiol (Oxf) 2024; 240:e14125. [PMID: 38533975 DOI: 10.1111/apha.14125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 01/30/2024] [Accepted: 02/14/2024] [Indexed: 03/28/2024]
Abstract
AIM Trafficking, membrane retention, and signal-specific regulation of the Na+/H+ exchanger 3 (NHE3) are modulated by the Na+/H+ Exchanger Regulatory Factor (NHERF) family of PDZ-adapter proteins. This study explored the assembly of NHE3 and NHERF2 with the cGMP-dependent kinase II (cGKII) within detergent-resistant membrane microdomains (DRMs, "lipid rafts") during in vivo guanylate cycle C receptor (Gucy2c) activation in murine small intestine. METHODS Small intestinal brush border membranes (siBBMs) were isolated from wild type, NHE3-deficient, cGMP-kinase II-deficient, and NHERF2-deficient mice, after oral application of the heat-stable Escherichia coli toxin (STa) analog linaclotide. Lipid raft and non-raft fractions were separated by Optiprep density gradient centrifugation of Triton X-solubilized siBBMs. Confocal microscopy was performed to study NHE3 redistribution after linaclotide application in vivo. RESULTS In the WT siBBM, NHE3, NHERF2, and cGKII were strongly raft associated. The raft association of NHE3, but not of cGKII, was NHERF2 dependent. After linaclotide application to WT mice, lipid raft association of NHE3 decreased, that of cGKII increased, while that of NHERF2 did not change. NHE3 expression in the BBM shifted from a microvillar to a terminal web region. The linaclotide-induced decrease in NHE3 raft association and in microvillar abundance was abolished in cGKII-deficient mice, and strongly reduced in NHERF2-deficient mice. CONCLUSION NHE3, cGKII, and NHERF2 form a lipid raft-associated signal complex in the siBBM, which mediates the inhibition of salt and water absorption by Gucy2c activation. NHERF2 enhances the raft association of NHE3, which is essential for its close interaction with the exclusively raft-associated activated cGKII.
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Affiliation(s)
- Min Luo
- Department of Gastroenterology, Hepatology, Infectiology and Endocrinology, Hannover Medical School, Hannover, Germany
- Department of Infectious Diseases, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Yongjian Liu
- Department of Gastroenterology, Hepatology, Infectiology and Endocrinology, Hannover Medical School, Hannover, Germany
- Department of Endocrinology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Katerina Nikolovska
- Department of Gastroenterology, Hepatology, Infectiology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Brigitte Riederer
- Department of Gastroenterology, Hepatology, Infectiology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Enrico Patrucco
- Institut für Pharmakologie und Toxikologie, TU München, München, Germany
- Department of Molecular Biotechnology and Health Science, University of Torino, Torino, Italy
| | - Franz Hofmann
- Institut für Pharmakologie und Toxikologie, TU München, München, Germany
| | - Ursula Seidler
- Department of Gastroenterology, Hepatology, Infectiology and Endocrinology, Hannover Medical School, Hannover, Germany
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Tse CM, Zhang Z, Lin R, Sarker R, Donowitz M, Singh V. The Air-Liquid Interface Reorganizes Membrane Lipids and Enhances the Recruitment of Slc26a3 to Lipid-Rich Domains in Human Colonoid Monolayers. Int J Mol Sci 2023; 24:8273. [PMID: 37175979 PMCID: PMC10179158 DOI: 10.3390/ijms24098273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 05/02/2023] [Accepted: 05/03/2023] [Indexed: 05/15/2023] Open
Abstract
Cholesterol-rich membrane domains, also called lipid rafts (LRs), are specialized membrane domains that provide a platform for intracellular signal transduction. Membrane proteins often cluster in LRs that further aggregate into larger platform-like structures that are enriched in ceramides and are called ceramide-rich platforms (CRPs). The role of CRPs in the regulation of intestinal epithelial functions remains unknown. Down-regulated in adenoma (DRA) is an intestinal Cl-/HCO3- antiporter that is enriched in LRs. However, little is known regarding the mechanisms involved in the regulation of DRA activity. The air-liquid interface (ALI) was created by removing apical media for a specified number of days; from 12-14 days post-confluency, Caco-2/BBe cells or a colonoid monolayer were grown as submerged cultures. Confocal imaging was used to examine the dimensions of membrane microdomains that contained DRA. DRA expression and activity were enhanced in Caco-2/BBe cells and human colonoids using an ALI culture method. ALI causes an increase in acid sphingomyelinase (ASMase) activity, an enzyme responsible for enhancing ceramide content in the plasma membrane. ALI cultures expressed a larger number of DRA-containing platforms with dimensions >2 µm compared to cells grown as submerged cultures. ASMase inhibitor, desipramine, disrupted CRPs and reduced the ALI-induced increase in DRA expression in the apical membrane. Exposing normal human colonoid monolayers to ALI increased the ASMase activity and enhanced the differentiation of colonoids along with basal and forskolin-stimulated DRA activities. ALI increases DRA activity and expression by increasing ASMase activity and platform formation in Caco-2/BBe cells and by enhancing the differentiation of colonoids.
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Affiliation(s)
- C. Ming Tse
- Division of Gastroenterology & Hepatology, Department of Medicine, School of Medicine, The Johns Hopkins University, 720 Rutland Avenue, 933 Ross Research Building, Baltimore, MD 21205, USA
| | - Zixin Zhang
- Division of Gastroenterology & Hepatology, Department of Medicine, School of Medicine, The Johns Hopkins University, 720 Rutland Avenue, 933 Ross Research Building, Baltimore, MD 21205, USA
| | - Ruxian Lin
- Division of Gastroenterology & Hepatology, Department of Medicine, School of Medicine, The Johns Hopkins University, 720 Rutland Avenue, 933 Ross Research Building, Baltimore, MD 21205, USA
| | - Rafiquel Sarker
- Division of Gastroenterology & Hepatology, Department of Medicine, School of Medicine, The Johns Hopkins University, 720 Rutland Avenue, 933 Ross Research Building, Baltimore, MD 21205, USA
| | - Mark Donowitz
- Division of Gastroenterology & Hepatology, Department of Medicine, School of Medicine, The Johns Hopkins University, 720 Rutland Avenue, 933 Ross Research Building, Baltimore, MD 21205, USA
- Department of Cellular and Molecular Physiology, School of Medicine, The Johns Hopkins University, Baltimore, MD 21205, USA
| | - Varsha Singh
- Division of Gastroenterology & Hepatology, Department of Medicine, School of Medicine, The Johns Hopkins University, 720 Rutland Avenue, 933 Ross Research Building, Baltimore, MD 21205, USA
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Jiang X, Liu Y, Zhang XY, Liu X, Liu X, Wu X, Jose PA, Duan S, Xu FJ, Yang Z. Intestinal Gastrin/CCKBR (Cholecystokinin B Receptor) Ameliorates Salt-Sensitive Hypertension by Inhibiting Intestinal Na +/H + Exchanger 3 Activity Through a PKC (Protein Kinase C)-Mediated NHERF1 and NHERF2 Pathway. Hypertension 2022; 79:1668-1679. [PMID: 35674015 PMCID: PMC9278716 DOI: 10.1161/hypertensionaha.121.18791] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background: The present study directly tested the crucial role of intestinal gastrin/CCKBR (cholecystokinin B receptor) in the treatment of salt-sensitive hypertension. Methods: Adult intestine-specific Cckbr-knockout mice (Cckbrfl/flvillin-Cre) and Dahl salt-sensitive rats were studied on the effect of high salt intake (8% NaCl, 6–7 weeks) on intestinal Na+/H+ exchanger 3 expression, urine sodium concentration, and blood pressure. High-salt diet increased urine sodium concentration and systolic blood pressure to a greater extent in Cckbrfl/flvillin-Cre mice and Dahl salt-sensitive rats than their respective controls, Cckbrfl/flvillin mice and SS13BN rats. We constructed gastrin-SiO2 microspheres to enable gastrin to stimulate specifically and selectively intestinal CCKBR without its absorption into the circulation. Results: Gastrin-SiO2 microspheres treatment prevented the high salt-induced hypertension and increase in urine Na concentration by inhibiting intestinal Na+/H+ exchanger 3 trafficking and activity, increasing stool sodium without inducing diarrhea. Gastrin-mediated inhibition of intestinal Na+/H+ exchanger 3 activity, related to a PKC (protein kinase C)-mediated activation of NHERF1 and NHERF2. Conclusions: These results support a crucial role of intestinal gastrin/CCKBR in decreasing intestinal sodium absorption and keeping the blood pressure in the normal range. The gastrointestinal administration of gastrin-SiO2 microspheres is a promising and safe strategy to treat salt-sensitive hypertension without side effects.
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Affiliation(s)
- Xiaoliang Jiang
- NHC Key Laboratory of Human Disease Comparative Medicine (The Institute of Laboratory Animal Sciences, CAMS&PUMC), National Human Diseases Animal Model Resource Center, Beijing Engineering Research Center for Experimental Animal Models of Human Critical Diseases, P.R. China (X.J., Y.L., Xue Liu, Xing Liu, X.W., Z.Y.)
| | - Yunpeng Liu
- NHC Key Laboratory of Human Disease Comparative Medicine (The Institute of Laboratory Animal Sciences, CAMS&PUMC), National Human Diseases Animal Model Resource Center, Beijing Engineering Research Center for Experimental Animal Models of Human Critical Diseases, P.R. China (X.J., Y.L., Xue Liu, Xing Liu, X.W., Z.Y.)
| | - Xin-Yang Zhang
- Key Lab of Biomedical Materials of Natural Macromolecules (Beijing University of Chemical Technology), Ministry of Education, Beijing Laboratory of Biomedical Materials, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, P.R. China (X.-Y.Z., S.D., F.-J.X.)
| | - Xue Liu
- NHC Key Laboratory of Human Disease Comparative Medicine (The Institute of Laboratory Animal Sciences, CAMS&PUMC), National Human Diseases Animal Model Resource Center, Beijing Engineering Research Center for Experimental Animal Models of Human Critical Diseases, P.R. China (X.J., Y.L., Xue Liu, Xing Liu, X.W., Z.Y.)
| | - Xing Liu
- NHC Key Laboratory of Human Disease Comparative Medicine (The Institute of Laboratory Animal Sciences, CAMS&PUMC), National Human Diseases Animal Model Resource Center, Beijing Engineering Research Center for Experimental Animal Models of Human Critical Diseases, P.R. China (X.J., Y.L., Xue Liu, Xing Liu, X.W., Z.Y.)
| | - Xianxian Wu
- NHC Key Laboratory of Human Disease Comparative Medicine (The Institute of Laboratory Animal Sciences, CAMS&PUMC), National Human Diseases Animal Model Resource Center, Beijing Engineering Research Center for Experimental Animal Models of Human Critical Diseases, P.R. China (X.J., Y.L., Xue Liu, Xing Liu, X.W., Z.Y.)
| | - Pedro A Jose
- Department of Pharmacology and Physiology (P.A.J.), The George Washington University School of Medicine and Health Sciences, Washington, DC.,Division of Kidney Diseases and Hypertension, Department of Medicine (P.A.J.), The George Washington University School of Medicine and Health Sciences, Washington, DC
| | - Shun Duan
- Key Lab of Biomedical Materials of Natural Macromolecules (Beijing University of Chemical Technology), Ministry of Education, Beijing Laboratory of Biomedical Materials, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, P.R. China (X.-Y.Z., S.D., F.-J.X.)
| | - Fu-Jian Xu
- Key Lab of Biomedical Materials of Natural Macromolecules (Beijing University of Chemical Technology), Ministry of Education, Beijing Laboratory of Biomedical Materials, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, P.R. China (X.-Y.Z., S.D., F.-J.X.)
| | - Zhiwei Yang
- NHC Key Laboratory of Human Disease Comparative Medicine (The Institute of Laboratory Animal Sciences, CAMS&PUMC), National Human Diseases Animal Model Resource Center, Beijing Engineering Research Center for Experimental Animal Models of Human Critical Diseases, P.R. China (X.J., Y.L., Xue Liu, Xing Liu, X.W., Z.Y.)
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Cure E, Cumhur Cure M. Strong relationship between cholesterol, low-density lipoprotein receptor, Na +/H + exchanger, and SARS-COV-2: this association may be the cause of death in the patient with COVID-19. Lipids Health Dis 2021; 20:179. [PMID: 34895256 PMCID: PMC8666266 DOI: 10.1186/s12944-021-01607-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Lipids have a wide variety and vital functions. Lipids play roles in energy metabolism, intracellular and extracellular signal traffic, and transport of fat-soluble vitamins. Also, they form the structure of the cell membrane. SARS-CoV-2 interacts with lipids since its genetic material contains lipid-enveloped ribonucleic acid (RNA). Previous studies have shown that total cholesterol, high-density lipoprotein, and low-density lipoprotein (LDL) levels are lower in patients with severe novel coronavirus disease 2019 (COVID-19) compared to patients with non-severe COVID-19.Na+/H+ Exchanger (NHE) is an important antiport that keeps the intracellular pH value within physiological limits. When the intracellular pH falls, NHE is activated and pumps H+ ions outward. However, prolonged NHE activation causes cell damage and atherosclerosis. Prolonged NHE activation may increase susceptibility to SARS-CoV-2 infection and severity of COVID-19.In COVID-19, increased angiotensin II (Ang II) due to angiotensin-converting enzyme-2 (ACE2) dysfunction stimulates NHE. Lipids are in close association with the NHE pump. Prolonged NHE activity increases the influx of H+ ions and free fatty acid (FFA) inward. Ang II also causes increased low-density lipoprotein receptor (LDLR) levels by inhibiting proprotein convertase subtilisin/kexin type 9 (PCSK9). Thus, intracellular atheroma plaque formation is accelerated.Besides, SARS-CoV-2 may replicate more rapidly as intracellular cholesterol increases. SARS-CoV-2 swiftly infects the cell whose intracellular pH decreases with NHE activation and FFA movement. Novel treatment regimens based on NHE and lipids should be explored for the treatment of COVID-19.
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Affiliation(s)
- Erkan Cure
- Department of Internal Medicine, Bagcilar Medilife Hospital, 34200 Istanbul, Turkey
| | - Medine Cumhur Cure
- Department of Biochemistry, Private Kucukcekmece Hospital, Istanbul, Turkey
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5
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Cure E, Cumhur Cure M. Strong relationship between cholesterol, low-density lipoprotein receptor, Na +/H + exchanger, and SARS-COV-2: this association may be the cause of death in the patient with COVID-19. Lipids Health Dis 2021. [PMID: 34895256 DOI: 10.1186/s12944-021-01607-5.] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Lipids have a wide variety and vital functions. Lipids play roles in energy metabolism, intracellular and extracellular signal traffic, and transport of fat-soluble vitamins. Also, they form the structure of the cell membrane. SARS-CoV-2 interacts with lipids since its genetic material contains lipid-enveloped ribonucleic acid (RNA). Previous studies have shown that total cholesterol, high-density lipoprotein, and low-density lipoprotein (LDL) levels are lower in patients with severe novel coronavirus disease 2019 (COVID-19) compared to patients with non-severe COVID-19.Na+/H+ Exchanger (NHE) is an important antiport that keeps the intracellular pH value within physiological limits. When the intracellular pH falls, NHE is activated and pumps H+ ions outward. However, prolonged NHE activation causes cell damage and atherosclerosis. Prolonged NHE activation may increase susceptibility to SARS-CoV-2 infection and severity of COVID-19.In COVID-19, increased angiotensin II (Ang II) due to angiotensin-converting enzyme-2 (ACE2) dysfunction stimulates NHE. Lipids are in close association with the NHE pump. Prolonged NHE activity increases the influx of H+ ions and free fatty acid (FFA) inward. Ang II also causes increased low-density lipoprotein receptor (LDLR) levels by inhibiting proprotein convertase subtilisin/kexin type 9 (PCSK9). Thus, intracellular atheroma plaque formation is accelerated.Besides, SARS-CoV-2 may replicate more rapidly as intracellular cholesterol increases. SARS-CoV-2 swiftly infects the cell whose intracellular pH decreases with NHE activation and FFA movement. Novel treatment regimens based on NHE and lipids should be explored for the treatment of COVID-19.
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Affiliation(s)
- Erkan Cure
- Department of Internal Medicine, Bagcilar Medilife Hospital, 34200, Istanbul, Turkey.
| | - Medine Cumhur Cure
- Department of Biochemistry, Private Kucukcekmece Hospital, Istanbul, Turkey
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6
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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.
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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
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Niu Z, Zhang Y, Kan Z, Ran L, Yan T, Xu S, Zhang S, Zhang J, Zou H, Song Z. Decreased NHE3 activity in intestinal epithelial cells in TGEV and PEDV-induced piglet diarrhea. Vet Microbiol 2021; 263:109263. [PMID: 34749283 DOI: 10.1016/j.vetmic.2021.109263] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Accepted: 10/17/2021] [Indexed: 11/16/2022]
Abstract
Transmissible gastroenteritis (TGE) and porcine epidemic diarrhea (PED) are highly transmissible intestinal infections caused by transmissible gastroenteritis virus (TGEV) and porcine epidemic diarrhea virus (PEDV), respectively. They are clinically associated with vomiting, diarrhea, and dehydration in piglets. An imbalance in Na+ uptake by intestinal epithelial cells causes TGEV/PEDV-induced diarrhea. However, the mechanism by which TGEV/PEDV-infection in piglets causes Na+ imbalance diarrhea has not been elucidated. In the present study, we demonstrated that specific inhibition of NHE3 activity caused small intestinal bulging, intestinal wall thinning and severe diarrhea in piglets, consistent with the signs of TGEV/PEDV infection. This study further elucidated the role of NHE3 in TGEV/PEDV-induced diarrhea. In this study, small intestinal epithelial cells (IPEC-J2) were used as a model of infection. The results showed that TGEV/PEDV infection reduced NHE3 activity and Na+ uptake in IPEC-J2 cells. Further studies revealed that the use of NHE3-specific inhibitors could reduce the amount of cell membrane NHE3, thereby decreasing Na+ uptake and ultimately leading to diarrhea. Transcriptomic studies performed on obtained jejunal tissues were also consistent with pre-laboratory results. This study will provide a basis for understanding Na+ imbalance diarrhea caused by TGEV/PEDV, as well as for elucidating the diarrheal pathogenesis of other members of α-animal coronaviruses.
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Affiliation(s)
- Zheng Niu
- College of Veterinary Medicine, Southwest University, Chongqing, China; Immunology Research Center, Medical Research Institute, Southwest University, Chongqing, China.
| | - YiLing Zhang
- College of Veterinary Medicine, Southwest University, Chongqing, China.
| | - ZiFei Kan
- College of Veterinary Medicine, Southwest University, Chongqing, China.
| | - Ling Ran
- College of Veterinary Medicine, Southwest University, Chongqing, China; Institute of Immunology, Third Military Medical University, Chongqing, China.
| | - Tao Yan
- Department of Preventive Veterinary Medicine, Medical College of Animals, Xinjiang Agricultural University, Ürümqi, China.
| | - ShaSha Xu
- College of Veterinary Medicine, Southwest University, Chongqing, China.
| | - ShuJuan Zhang
- College of Veterinary Medicine, Southwest University, Chongqing, China.
| | - JingYi Zhang
- College of Veterinary Medicine, Southwest University, Chongqing, China.
| | - Hong Zou
- College of Veterinary Medicine, Southwest University, Chongqing, China; Immunology Research Center, Medical Research Institute, Southwest University, Chongqing, China.
| | - ZhenHui Song
- College of Veterinary Medicine, Southwest University, Chongqing, China; Immunology Research Center, Medical Research Institute, Southwest University, Chongqing, China.
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Reduced activity of intestinal surface Na +/H + exchanger NHE3 is a key factor for induction of diarrhea after PEDV infection in neonatal piglets. Virology 2021; 563:64-73. [PMID: 34464882 DOI: 10.1016/j.virol.2021.08.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 07/26/2021] [Accepted: 08/19/2021] [Indexed: 11/20/2022]
Abstract
Porcine epidemic diarrhea virus (PEDV; family Coronaviridae, genus Alphacoronavirus) causes acute diarrhea and vomiting, dehydration, and high mortality in neonatal piglets. Despite extensive research focusing on the pathogenesis of PEDV infection, the molecular pathogenesis of PEDV-induced diarrhea in piglets remains unclear. Na+/H+ exchanger 3 (NHE3), the main exchanger of electroneutral sodium in intestinal epithelial cells, is closely associated with the occurrence of diarrhea. To date, there is no study on whether diarrhea caused by PEDV infection is related to the activity of NHE3. In the present study, it was found that the expression level of cell membrane protein NHE3 significantly decreased after PEDV infection, whereas the total level of protein expression was not significantly changed. The Na+/H+ transport rate and the mRNA abundance of NHE3 decreased; the NHE3 activity decreased gradually with increasing infection time. In vivo, after PEDV infection of newborn piglets, rupture of intestinal villi and interstitial degeneration of intestinal epithelial cells in different intestinal segments were observed by hematoxylin-eosin staining. Immunohistochemical and immunofluorescence methods were used to observe the decreased expression of NHE3 protein on the membrane of intestinal epithelial cells in the jejunum and ileum. Taken together, these data indicate that PEDV infection reduces NHE3 activity in intestinal epithelial cells, hindering Na+ transport and thus causing diarrhea.
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Differential expression of two ATPases revealed by lipid raft isolation from gills of euryhaline teleosts with different salinity preferences. Comp Biochem Physiol B Biochem Mol Biol 2021; 253:110562. [PMID: 33453387 DOI: 10.1016/j.cbpb.2021.110562] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Revised: 12/29/2020] [Accepted: 01/10/2021] [Indexed: 12/12/2022]
Abstract
In euryhaline teleosts, Na+, K+-ATPase (NKA) and V-type H + -ATPase A (VHA A) are important ion-transporters located in cell membrane. Lipid rafts (LR) are plasma membrane microdomains enriched in cholesterol, sphingolipids, and proteins (e.g., flotillin). Flotillin is a LR-associated protein, commonly used as the LR marker. Previous mammalian studies showed that LR may play a crucial role in ion exchanges. Meanwhile, studies on mammals and rainbow trout showed that NKA were found to be present mainly in LR. However, little is known about LR in fish. Therefore, the present study aimed to investigate the involvement of branchial LR in osmoregulation of tilapia and milkfish, two euryhaline teleosts with different salinity preferences, by (i) extracting LR from the gills of euryhaline teleosts; (ii) detecting the abundance of LR marker protein (flotillin-2) and ion-transporters (NKA and VHA A) in branchial LR and non-LR of fresh water- and seawater-acclimated milkfish and tilapia. The results indicated that the protein abundance of LR marker, flotillin-2, changed with environmental salinities in branchial LR of tilapia. In addition, flotillin-2 and NKA were only found in LR in both tilapia and milkfish gills, while VHA A were mainly present in non-LR. Relative protein abundance of NKA was found to be significantly higher in gills of freshwater milkfish and seawater tilapia, while VHA A was significantly higher in gills of freshwater tilapia and milkfish. This study illustrated differential distribution and salinity-dependent expression of NKA and VHA A in cell membrane of gill tissues of euryhaline teleosts with different salinity preferences.
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Han Y, Yun CC. Ubiquitin-specific peptidase 7 (USP7) and USP10 mediate deubiquitination of human NHE3 regulating its expression and activity. FASEB J 2020; 34:16476-16488. [PMID: 33095475 DOI: 10.1096/fj.202001875r] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 09/21/2020] [Accepted: 10/06/2020] [Indexed: 12/19/2022]
Abstract
Na+ /H+ exchanger NHE3 of human or primates differs from NHE3 of other animals by having a PY motif, which mediates interaction with the E3 ubiquitin (Ub) ligase Nedd4-2. Ub-conjugation of human NHE3 by Nedd4-2 regulates endocytosis of NHE3 but does not affect its cellular expression. Because Ub-conjugation is a reversible process, the aim of this study is to identify deubiquitinating enzyme (DUB) regulating the post-endosomal fate of human NHE3. Using an activity-based chemical screening, we identified ubiquitin specific protease-7 (USP7) and USP10 that bind NHE3. The roles of DUBs in regulation of NHE3 were studied by determining the effects of silencing of USP7 and USP10. Knockdown of USP7 or USP10 resulted in increased NHE3 ubiquitination and decreased NHE3 expression at the surface membrane and cellular level. The endocytic retrieval of NHE3 was promoted by depletion of USP7 or USP10, with increased association of NHE3 with Rab5a and Rab7. Inhibition of USP7 and USP10 by chemical inhibitors or knockdown had an additive effect on NHE3. In addition, NHE3 half-life was reduced accounting for decreased NHE3 protein abundance. NHE3 is inhibited by protein kinase A. Activation of PKA by forskolin decreased the binding of USP7 and USP10 to NHE3, while increasing ubiquitination of NHE3. Knockdown of USP10 had an additive effect on PKA-dependent inhibition of NHE3. These findings demonstrate that USP7 and USP10 are DUBs that regulate NHE3 ubiquitination and expression, and reveal a new mechanism of NHE3 inhibition involving DUBs.
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Affiliation(s)
- Yiran Han
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA.,Gastroenterology Research, Atlanta VA Medical Center, Decatur, GA, USA
| | - C Chris Yun
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA.,Gastroenterology Research, Atlanta VA Medical Center, Decatur, GA, USA.,Cell and Molecular Biology Research Program, Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA, USA
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11
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Bannert K, Berlin P, Reiner J, Lemcke H, David R, Engelmann R, Lamprecht G. SNX27 regulates DRA activity and mediates its direct recycling by PDZ-interaction in early endosomes at the apical pole of Caco2 cells. Am J Physiol Gastrointest Liver Physiol 2020; 318:G854-G869. [PMID: 32116023 DOI: 10.1152/ajpgi.00374.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
DRA (downregulated in adenoma, SLC26A3) and NHE3 (Na+/H+ exchanger 3, SLC9A3) together mediate intestinal electroneutral NaCl absorption. Both transporters contain PDZ (postsynaptic density 95, disc large, zonula occludens 1) binding motifs and interact with PDZ adaptor proteins regulating their activity and recycling. SNX27 (sorting nexin 27) contains a PDZ domain and is involved in the recycling of cargo proteins including NHE3. The interaction of SNX27 with DRA and its potential role for the activity and recycling of DRA have been evaluated in this study. SNX27 specifically interacts with DRA via its PDZ domain. The knockdown (KD) of SNX27 reduced DRA activity by 50% but was not accompanied by a decrease of DRA surface expression. This indicates that DRA is trafficked to specific functional domains in the plasma membrane in which DRA is particularly active. Consistently, the disruption of lipid raft integrity by methyl-β-cyclodextrin has an inhibitory effect on DRA activity that was strongly reduced after SNX27 KD. In differentiated intestinal Caco2 cells, superresolution microscopy and a novel quantitative axial approach revealed that DRA and SNX27 colocalize in rab5-positive early endosomes at the apical pole. SNX27 regulates the activity of DRA in the apical plasma membrane through binding with its PDZ domain. This interaction occurs in rab5-positive early endosomes at the apical pole of differentiated intestinal Caco2 cells. SNX27 is involved in the direct recycling of DRA to the plasma membrane where it is inserted into lipid rafts facilitating increased activity.NEW & NOTEWORTHY SNX27 has a PDZ domain and is involved in the regulation and recycling of transmembrane proteins. The role of SNX27 on the activity and recycling of the intestinal Cl-/HCO3- exchanger DRA has not yet been studied. This study shows that SNX27 directly interacts with DRA in early endosomes at the apical pole of intestinal Caco2 cells and mediates its direct recycling to facilitate high activity in lipid rafts in the apical plasma membrane.
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Affiliation(s)
- Karen Bannert
- Department of Gastroenterology and Endocrinology, Center for Internal Medicine, Rostock University Medical Center, Rostock, Germany
| | - Peggy Berlin
- Department of Gastroenterology and Endocrinology, Center for Internal Medicine, Rostock University Medical Center, Rostock, Germany
| | - Johannes Reiner
- Department of Gastroenterology and Endocrinology, Center for Internal Medicine, Rostock University Medical Center, Rostock, Germany
| | - Heiko Lemcke
- Department of Cardiac Surgery, Rostock University Medical Center, Rostock, Germany.,Department Life, Light and Matter, University of Rostock, Rostock, Germany
| | - Robert David
- Department of Cardiac Surgery, Rostock University Medical Center, Rostock, Germany.,Department Life, Light and Matter, University of Rostock, Rostock, Germany
| | - Robby Engelmann
- Institute of Immunology, Rostock University Medical Center, Rostock, Germany
| | - Georg Lamprecht
- Department of Gastroenterology and Endocrinology, Center for Internal Medicine, Rostock University Medical Center, Rostock, Germany
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12
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Yang Y, Yu Q, Song H, Ran L, Wang K, Xie L, Huang S, Niu Z, Zhang Y, Kan Z, Yan T, Song Z. Decreased NHE3 activity and trafficking in TGEV-infected IPEC-J2 cells via the SGLT1-mediated P38 MAPK/AKt2 pathway. Virus Res 2020; 280:197901. [PMID: 32070687 PMCID: PMC7114662 DOI: 10.1016/j.virusres.2020.197901] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 01/09/2020] [Accepted: 02/14/2020] [Indexed: 02/03/2023]
Abstract
Decreased of apical of NHE3 protein expression and Na+/H+ exchange activity after TGEV infected IPEC-J2. SGLT1 can regulation the trafficking of NHE3 by p38MAPK/AKt2 singal pathway and show a corporate relationship. TGEV infection causes an increase in the expression of total SGLT1 protein. TGEV infection attenuates the translocation and exchange activity of NHE3 via the p38MAPK/AKt2 signaling pathway.
Transmissible gastroenteritis virus (TGEV) primarily replicates in intestinal epithelial cells and causes severe damage to host cells, resulting in diarrhea. Surface NHE3 serves as the key regulatory site controlling electroneutral Na+ absorption. In this study, our results showed that the surface NHE3 content was significantly reduced following TGEV infection, whereas the total level of protein expression was not significantly changed, and NHE3 activity gradually decreased with prolonged infection time. We then inhibited SGLT1 expression by lentiviral interference and drug inhibition, respectively. Inhibition studies showed that the level of phosphorylation of the downstream key proteins, MAPKAPK-2 and EZRIN, in the SGLT1-mediated p38MAPK/AKt2 signaling pathway was significantly increased. The surface NHE3 expression was also significantly increased, and NHE3 activity was also significantly enhanced. These results demonstrate that a TGEV infection can inhibit NHE3 translocation and attenuates sodium-hydrogen exchange activity via the SGLT1-mediated p38MAPK/AKt2 signaling pathway, affecting cellular electrolyte absorption leading to diarrhea.
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Affiliation(s)
- Yang Yang
- Department of Veterinary Medicine Southwest University Chongqing People's Republic of China, Chongqing 402460, China
| | - Qiuhan Yu
- Department of Veterinary Medicine Southwest University Chongqing People's Republic of China, Chongqing 402460, China
| | - Han Song
- Department of Veterinary Medicine Southwest University Chongqing People's Republic of China, Chongqing 402460, China
| | - Ling Ran
- Department of Veterinary Medicine Southwest University Chongqing People's Republic of China, Chongqing 402460, China
| | - Kai Wang
- Department of Veterinary Medicine Southwest University Chongqing People's Republic of China, Chongqing 402460, China
| | - Luyi Xie
- Department of Veterinary Medicine Southwest University Chongqing People's Republic of China, Chongqing 402460, China
| | - Shilei Huang
- Department of Veterinary Medicine Southwest University Chongqing People's Republic of China, Chongqing 402460, China
| | - Zheng Niu
- Department of Veterinary Medicine Southwest University Chongqing People's Republic of China, Chongqing 402460, China
| | - Yilin Zhang
- Department of Veterinary Medicine Southwest University Chongqing People's Republic of China, Chongqing 402460, China
| | - Zifei Kan
- Department of Veterinary Medicine Southwest University Chongqing People's Republic of China, Chongqing 402460, China
| | - Tao Yan
- Department of Veterinary Medicine Southwest University Chongqing People's Republic of China, Chongqing 402460, China
| | - Zhenhui Song
- Department of Veterinary Medicine Southwest University Chongqing People's Republic of China, Chongqing 402460, China.
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13
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Pushpakumar S, Ahmad A, Ketchem CJ, Jose PA, Weinman EJ, Sen U, Lederer ED, Khundmiri SJ. Sodium-hydrogen exchanger regulatory factor-1 (NHERF1) confers salt sensitivity in both male and female models of hypertension in aging. Life Sci 2020; 243:117226. [PMID: 31904366 PMCID: PMC7015806 DOI: 10.1016/j.lfs.2019.117226] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 12/16/2019] [Accepted: 12/23/2019] [Indexed: 01/11/2023]
Abstract
Hypertension is a risk factor for premature death and roughly 50% of hypertensive patients are salt-sensitive. The incidence of salt-sensitive hypertension increases with age. However, the mechanisms of salt-sensitive hypertension are not well understood. We had demonstrated decreased renal sodium‑hydrogen exchanger regulatory factor 1 (NHERF1) expression in old salt-resistant F344 rats. Based on those studies we hypothesized that NHERF1 expression is required for the development of some forms of salt-sensitive hypertension. To address this hypothesis, we measured blood pressure in NHERF1 expressing salt-sensitive 4-mo and 24-mo-old male and female Fischer Brown Norway (FBN) rats male and female 18-mo-old NHERF1 knock-out (NHERF1-/-) mice and wild-type (WT) littermates on C57BL/6J background after feeding high salt (8% NaCl) diet for 7 days. Our data demonstrate that 8% salt diet increased blood pressure in both male and female 24-mo-old FBN rats but not in 4-mo-old FBN rats and in 18-mo-old male and female WT mice but not in NHERF1-/- mice. Renal dopamine 1 receptor (D1R) expression was decreased in 24-mo-old rats, compared with 4-mo-old FBN rats. However, sodium chloride cotransporter (NCC) expression increased in 24-mo-old FBN rats. In FBN rats, age had no effect on NaK ATPase α1 and NKCC2 expression. By contrast, high salt diet increased the renal expressions of NKCC2, and NCC in 24-mo-old FBN rats. High salt diet also increased NKCC2 and NCC expression in WT mice but not NHERF1-/- mice. Our data suggest that renal NHERF1 expression confers salt sensitivity with aging, associated with increased expression of sodium transporters.
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Affiliation(s)
- Sathnur Pushpakumar
- Department of Physiology, University of Louisville, Louisville, KY, United States of America
| | - Asrar Ahmad
- Department of Physiology and Biophysics, Howard University College of Medicine, Washington, DC, United States of America
| | - Corey J Ketchem
- Department of Medicine, Nephrology and Hypertension, University of Louisville, Louisville, KY, United States of America
| | - Pedro A Jose
- Department of Medicine, Division of Renal Diseases and Hypertension, The George Washington University, Washington, DC, United States of America
| | - Edward J Weinman
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, United States of America
| | - Utpal Sen
- Department of Physiology, University of Louisville, Louisville, KY, United States of America
| | - Eleanor D Lederer
- Department of Physiology, University of Louisville, Louisville, KY, United States of America; Department of Medicine, Nephrology and Hypertension, University of Louisville, Louisville, KY, United States of America; Robley Rex VA Medical Center, Louisville, KY, United States of America
| | - Syed J Khundmiri
- Department of Physiology and Biophysics, Howard University College of Medicine, Washington, DC, United States of America.
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14
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Singh V, Yang J, Yin J, Cole R, Tse M, Berman DE, Small SA, Petsko G, Donowitz M. Cholera toxin inhibits SNX27-retromer-mediated delivery of cargo proteins to the plasma membrane. J Cell Sci 2018; 131:jcs.218610. [PMID: 30030371 DOI: 10.1242/jcs.218610] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 06/22/2018] [Indexed: 12/14/2022] Open
Abstract
Cholera toxin (CT) causes severe diarrhea by increasing intracellular cAMP leading to a PKA-dependent increase in Cl- secretion through CFTR and decreased Na+ absorption through inhibition of Na+/H+ exchanger 3 (NHE3; also known as SLC9A3). The mechanism(s) by which CT inhibits NHE3 is partially understood, although no drug therapy has been successful at reversing this inhibition. We now describe that CT phosphorylates an amino acid in the PDZ domain of SNX27, which inhibits SNX27-mediated trafficking of NHE3 from the early endosomes to the plasma membrane (PM), and contributes to reduced basal NHE3 activity through a mechanism that involves reduced PM expression and reduced endocytic recycling. Importantly, mutagenesis studies (Ser to Asp) showed that the effect of this phosphorylation of SNX27 phenocopies the effects seen upon loss of SNX27 function, affecting PM trafficking of cargo proteins that bind SNX27-retromer. Additionally, CT destabilizes retromer function by decreasing the amount of core retromer proteins. These effects of CT can be partially rescued by enhancing retromer stability by using 'pharmacological chaperones'. Moreover, pharmacological chaperones can be used to increase basal and cholera toxin-inhibited NHE3 activity and fluid absorption by intestinal epithelial cells.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Varsha Singh
- Departments of Medicine and Physiology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Jianbo Yang
- Departments of Medicine and Physiology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Jianyi Yin
- Departments of Medicine and Physiology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Robert Cole
- Department of Biological Chemistry, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Ming Tse
- Departments of Medicine and Physiology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Diego E Berman
- The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Department of Pathology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
| | - Scott A Small
- The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Department of Pathology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
| | - Gregory Petsko
- Helen and Robert Appel Alzheimer's Disease Research Institute and Department of Neurology, Weill Cornell Medical College, New York, NY 10021, USA
| | - Mark Donowitz
- Departments of Medicine and Physiology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
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15
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Klinger S, Breves G. Resveratrol Inhibits Porcine Intestinal Glucose and Alanine Transport: Potential Roles of Na⁺/K⁺-ATPase Activity, Protein Kinase A, AMP-Activated Protein Kinase and the Association of Selected Nutrient Transport Proteins with Detergent Resistant Membranes. Nutrients 2018; 10:nu10030302. [PMID: 29510506 PMCID: PMC5872720 DOI: 10.3390/nu10030302] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 02/24/2018] [Accepted: 03/01/2018] [Indexed: 12/22/2022] Open
Abstract
Background: Beneficial effects of Resveratrol (RSV) have been demonstrated, including effects on transporters and channels. However, little is known about how RSV influences intestinal transport. The aim of this study was to further characterize the effects of RSV on intestinal transport and the respective mechanisms. Methods: Porcine jejunum and ileum were incubated with RSV (300 µM, 30 min) in Ussing chambers (functional studies) and tissue bathes (detection of protein expression, phosphorylation, association with detergent resistant membranes (DRMs)). Results: RSV reduced alanine and glucose-induced short circuit currents (ΔIsc) and influenced forskolin-induced ΔIsc. The phosphorylation of sodium–glucose-linked transporter 1 (SGLT1), AMP-activated protein kinase (AMPK), protein kinase A substrates (PKA-S) and liver kinase B1 (LKB1) increased but a causative relation to the inhibitory effects could not directly be established. The DRM association of SGLT1, peptide transporter 1 (PEPT1) and (phosphorylated) Na+/H+-exchanger 3 (NHE3) did not change. Conclusion: RSV influences the intestinal transport of glucose, alanine and chloride and is likely to affect other transport processes. As the effects of protein kinase activation vary between the intestinal localizations, it would appear that increasing cyclic adenosine monophosphate (cAMP) levels are part of the mechanism. Nonetheless, the physiological responses depend on cell type-specific structures.
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Affiliation(s)
- Stefanie Klinger
- Department of Physiology, University of Veterinary Medicine Hannover, Foundation, Bischofsholer Damm 15, 30173 Hannover, Germany.
| | - Gerhard Breves
- Department of Physiology, University of Veterinary Medicine Hannover, Foundation, Bischofsholer Damm 15, 30173 Hannover, Germany.
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16
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Avula LR, Chen T, Kovbasnjuk O, Donowitz M. Both NHERF3 and NHERF2 are necessary for multiple aspects of acute regulation of NHE3 by elevated Ca 2+, cGMP, and lysophosphatidic acid. Am J Physiol Gastrointest Liver Physiol 2018; 314:G81-G90. [PMID: 28882822 PMCID: PMC5866371 DOI: 10.1152/ajpgi.00140.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The intestinal epithelial brush border Na+/H+ exchanger NHE3 accounts for a large component of intestinal Na absorption. NHE3 is regulated during digestion by signaling complexes on its COOH terminus that include the four multi-PDZ domain-containing NHERF family proteins. All bind to NHE3 and take part in different aspects of NHE3 regulation. Because the roles of each NHERF appear to vary on the basis of the cell model or intestinal segment studied and because of our recent finding that a NHERF3-NHERF2 heterodimer appears important for NHE3 regulation in Caco-2 cells, we examined the role of NHERF3 and NHERF2 in C57BL/6 mouse jejunum using homozygous NHERF2 and NHERF3 knockout mice. NHE3 activity was determined with two-photon microscopy and the dual-emission pH-sensitive dye SNARF-4F. The jejunal apical membrane of NHERF3-null mice appeared similar to wild-type (WT) mice in surface area, microvillus number, and height, which is similar to results previously reported for jejunum of NHERF2-null mice. NHE3 basal activity was not different from WT in either NHERF2- or NHERF3-null jejunum, while d-glucose-stimulated NHE3 activity was reduced in NHERF2, but similar to WT in NHERF3 KO. LPA stimulation and UTP (elevated Ca2+) and cGMP inhibition of NHE3 were markedly reduced in both NHERF2- and NHERF3-null jejunum. Forskolin inhibited NHE3 in NHERF3-null jejunum, but the extent of inhibition was reduced compared with WT. The forskolin inhibition of NHE3 in NHERF2-null mice was too inconsistent to determine whether there was an effect and whether it was altered compared with the WT response. These results demonstrate similar requirement for NHERF2 and NHERF3 in mouse jejunal NHE3 regulation by LPA, Ca2+, and cGMP. The explanation for the similarity is not known but is consistent with involvement of a brush-border NHERF3-NHERF2 heterodimer or sequential NHERF-dependent effects in these aspects of NHE3 regulation. NEW & NOTEWORTHY NHERF2 and NHERF3 are apical membrane multi-PDZ domain-containing proteins that are involved in regulation of intestinal NHE3. This study demonstrates that NHERF2 and NHERF3 have overlapping roles in NHE3 stimulation by LPA and inhibition by elevated Ca2+ and cGMP. These results are consistent with their role being as a NHERF3-NHERF2 heterodimer or via sequential NHERF-dependent signaling steps, and they begin to clarify a role for multiple NHERF proteins in NHE3 regulation.
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Affiliation(s)
- Leela Rani Avula
- 1Department of Medicine, the Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Tiane Chen
- 1Department of Medicine, the Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Olga Kovbasnjuk
- 1Department of Medicine, the Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Mark Donowitz
- 1Department of Medicine, the Johns Hopkins School of Medicine, Baltimore, Maryland,2Department of Physiology, the Johns Hopkins University School of Medicine, Baltimore, Maryland
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17
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Barati MT, Ketchem CJ, Merchant ML, Kusiak WB, Jose PA, Weinman EJ, LeBlanc AJ, Lederer ED, Khundmiri SJ. Loss of NHERF-1 expression prevents dopamine-mediated Na-K-ATPase regulation in renal proximal tubule cells from rat models of hypertension: aged F344 rats and spontaneously hypertensive rats. Am J Physiol Cell Physiol 2017; 313:C197-C206. [PMID: 28515088 DOI: 10.1152/ajpcell.00219.2016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 05/08/2017] [Accepted: 05/08/2017] [Indexed: 01/11/2023]
Abstract
Dopamine decreases Na-K-ATPase (NKA) activity by PKC-dependent phosphorylation and endocytosis of the NKA α1. Dopamine-mediated regulation of NKA is impaired in aging and some forms of hypertension. Using opossum (OK) proximal tubule cells (PTCs), we demonstrated that sodium-hydrogen exchanger regulatory factor-1 (NHERF-1) associates with NKA α1 and dopamine-1 receptor (D1R). This association is required for the dopamine-mediated regulation of NKA. In OK cells, dopamine decreases NHERF-1 association with NKA α1 but increases its association with D1R. However, it is not known whether NHERF-1 plays a role in dopamine-mediated NKA regulation in animal models of hypertension. We hypothesized that defective dopamine-mediated regulation of NKA results from the decrease in NHERF-1 expression in rat renal PTCs isolated from animal models of hypertension [spontaneously hypertensive rats (SHRs) and aged F344 rats]. To test this hypothesis, we isolated and cultured renal PTCs from 22-mo-old F344 rats and their controls, normotensive 4-mo-old F344 rats, and SHRs and their controls, normotensive Wistar-Kyoto (WKY) rats. The results demonstrate that in both hypertensive models (SHR and aged F344), NHERF-1 expression, dopamine-mediated phosphorylation of NKA, and ouabain-inhibitable K+ transport are reduced. Transfection of NHERF-1 into PTCs from aged F344 and SHRs restored dopamine-mediated inhibition of NKA. These results suggest that decreased renal NHERF-1 expression contributes to the impaired dopamine-mediated inhibition of NKA in PTCs from animal models of hypertension.
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Affiliation(s)
- Michelle T Barati
- Department of Medicine, Nephrology and Hypertension, University of Louisville, Louisville, Kentucky
| | - Corey J Ketchem
- Department of Medicine, Nephrology and Hypertension, University of Louisville, Louisville, Kentucky
| | - Michael L Merchant
- Department of Medicine, Nephrology and Hypertension, University of Louisville, Louisville, Kentucky
| | - Walter B Kusiak
- Department of Medicine, Nephrology and Hypertension, University of Louisville, Louisville, Kentucky
| | - Pedro A Jose
- Department of Medicine, Division of Renal Diseases and Hypertension, and Department of Pharmacology and Physiology, The George Washington University, Washington, District of Columbia
| | - Edward J Weinman
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Amanda J LeBlanc
- Department of Physiology, University of Louisville, Louisville, Kentucky
| | - Eleanor D Lederer
- Department of Medicine, Nephrology and Hypertension, University of Louisville, Louisville, Kentucky.,Department of Physiology, University of Louisville, Louisville, Kentucky.,Robley Rex VA Medical Center, Louisville, Kentucky; and
| | - Syed J Khundmiri
- Department of Physiology and Biophysics, Howard University College of Medicine, Washington, District of Columbia
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18
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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.
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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
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19
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Chen Y, Wu S, Tian Y, Kong J. Phosphorylation and subcellular localization of Na+/H+ exchanger isoform 3 (NHE3) are associated with altered gallbladder absorptive function after formation of cholesterol gallstones. J Physiol Biochem 2016; 73:133-139. [DOI: 10.1007/s13105-016-0533-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Accepted: 10/21/2016] [Indexed: 01/14/2023]
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20
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Villar VAM, Cuevas S, Zheng X, Jose PA. Localization and signaling of GPCRs in lipid rafts. Methods Cell Biol 2016; 132:3-23. [DOI: 10.1016/bs.mcb.2015.11.008] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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21
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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.
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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
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Singh V, Yang J, Cha B, Chen TE, Sarker R, Yin J, Avula LR, Tse M, Donowitz M. Sorting nexin 27 regulates basal and stimulated brush border trafficking of NHE3. Mol Biol Cell 2015; 26:2030-43. [PMID: 25851603 PMCID: PMC4472014 DOI: 10.1091/mbc.e14-12-1597] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 04/01/2015] [Indexed: 12/21/2022] Open
Abstract
In polarized epithelial cells, SNX27 regulates PDZ domain–directed trafficking of NHE3 from endosomes to the plasma membrane and increases the stability of brush border NHE3. This establishes SNX27 as an important regulator of polarized sorting in epithelial cells. Sorting nexin 27 (SNX27) contains a PDZ domain that is phylogenetically related to the PDZ domains of the NHERF proteins. Studies on nonepithelial cells have shown that this protein is located in endosomes, where it regulates trafficking of cargo proteins in a PDZ domain–dependent manner. However, the role of SNX27 in trafficking of cargo proteins in epithelial cells has not been adequately explored. Here we show that SNX27 directly interacts with NHE3 (C-terminus) primarily through the SNX27 PDZ domain. A combination of knockdown and reconstitution experiments with wild type and a PDZ domain mutant (GYGF → GAGA) of SNX27 demonstrate that the PDZ domain of SNX27 is required to maintain basal NHE3 activity and surface expression of NHE3 in polarized epithelial cells. Biotinylation-based recycling and degradation studies in intestinal epithelial cells show that SNX27 is required for the exocytosis (not endocytosis) of NHE3 from early endosome to plasma membrane. SNX27 is also required to regulate the retention of NHE3 on the plasma membrane. The findings of the present study extend our understanding of PDZ-mediated recycling of cargo proteins from endosome to plasma membrane in epithelial cells.
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Affiliation(s)
- Varsha Singh
- Gastroenterology Division, Departments of Physiology and Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Jianbo Yang
- Gastroenterology Division, Departments of Physiology and Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Boyoung Cha
- Gastroenterology Division, Departments of Physiology and Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Tiane-e Chen
- Gastroenterology Division, Departments of Physiology and Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Rafiquel Sarker
- Gastroenterology Division, Departments of Physiology and Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Jianyi Yin
- Gastroenterology Division, Departments of Physiology and Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Leela Rani Avula
- Gastroenterology Division, Departments of Physiology and Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Ming Tse
- Gastroenterology Division, Departments of Physiology and Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Mark Donowitz
- Gastroenterology Division, Departments of Physiology and Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205
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23
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Chen Y, Kong J, Wu S. Cholesterol gallstone disease: focusing on the role of gallbladder. J Transl Med 2015; 95:124-31. [PMID: 25502177 DOI: 10.1038/labinvest.2014.140] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 10/11/2014] [Accepted: 10/15/2014] [Indexed: 02/06/2023] Open
Abstract
Gallstone disease (GSD) is one of the most common biliary tract diseases worldwide in which both genetic and environmental factors have roles in its pathogenesis. Biliary cholesterol supersaturation from metabolic defects in the liver is traditionally seen as the main pathogenic factor. Recently, there have been renewed investigative interests in the downstream events that occur in gallbladder lithogenesis. This article focuses on the role of the gallbladder in the pathogenesis of cholesterol GSD (CGD). Various conditions affecting the crystallization process are discussed, such as gallbladder motility, concentrating function, lipid transport, and an imbalance between pro-nucleating and nucleation inhibiting proteins.
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Affiliation(s)
- Yongsheng Chen
- Department of General Surgery, Shengjing Hospital of China Medical University, Shenyang, China
| | - Jing Kong
- Department of General Surgery, Shengjing Hospital of China Medical University, Shenyang, China
| | - Shuodong Wu
- Department of General Surgery, Shengjing Hospital of China Medical University, Shenyang, China
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24
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Chen T, Kocinsky HS, Cha B, Murtazina R, Yang J, Tse CM, Singh V, Cole R, Aronson PS, de Jonge H, Sarker R, Donowitz M. Cyclic GMP kinase II (cGKII) inhibits NHE3 by altering its trafficking and phosphorylating NHE3 at three required sites: identification of a multifunctional phosphorylation site. J Biol Chem 2014; 290:1952-65. [PMID: 25480791 DOI: 10.1074/jbc.m114.590174] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The epithelial brush-border Na(+)/H(+) exchanger NHE3 is acutely inhibited by cGKII/cGMP, but how cGKII inhibits NHE3 is unknown. This study tested the hypothesis that cGMP inhibits NHE3 by phosphorylating it and altering its membrane trafficking. Studies were carried out in PS120/NHERF2 and in Caco-2/Bbe cells overexpressing HA-NHE3 and cGKII, and in mouse ileum. NHE3 activity was measured with 2',7'-bis(carboxyethyl)-S-(and 6)carboxyfluorescein acetoxy methylester/fluorometry. Surface NHE3 was determined by cell surface biotinylation. Identification of NHE3 phosphorylation sites was by iTRAQ/LC-MS/MS with TiO2 enrichment and immunoblotting with specific anti-phospho-NHE3 antibodies. cGMP/cGKII rapidly inhibited NHE3, which was associated with reduced surface NHE3. cGMP/cGKII increased NHE3 phosphorylation at three sites (rabbit Ser(554), Ser(607), and Ser(663), equivalent to mouse Ser(552), Ser(605), and Ser(659)), all of which had to be present at the same time for cGMP to inhibit NHE3. NHE3-Ser(663) phosphorylation was not necessary for cAMP inhibition of NHE3. Dexamethasone (4 h) stimulated wild type NHE3 activity and increased surface expression but failed to stimulate NHE3 activity or increase surface expression when NHE3 was mutated to either S663A or S663D. We conclude that 1) cGMP inhibition of NHE3 is associated with phosphorylation of NHE3 at Ser(554), Ser(607), and Ser(663), all of which are necessary for cGMP/cGKII to inhibit NHE3. 2) Dexamethasone stimulates NHE3 by phosphorylation of a single site, Ser(663). The requirement for three phosphorylation sites in NHE3 for cGKII inhibition, and for phosphorylation of one of these sites for dexamethasone stimulation of NHE3, is a unique example of regulation by phosphorylation.
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Affiliation(s)
- Tiane Chen
- From the Departments of Physiology and Medicine, Gastroenterology Division, and
| | | | - Boyoung Cha
- From the Departments of Physiology and Medicine, Gastroenterology Division, and
| | - Rakhilya Murtazina
- From the Departments of Physiology and Medicine, Gastroenterology Division, and
| | - Jianbo Yang
- From the Departments of Physiology and Medicine, Gastroenterology Division, and
| | - C Ming Tse
- From the Departments of Physiology and Medicine, Gastroenterology Division, and
| | - Varsha Singh
- From the Departments of Physiology and Medicine, Gastroenterology Division, and
| | - Robert Cole
- the Biological Chemistry Department, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Peter S Aronson
- Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520, and
| | - Hugo de Jonge
- the GI Division, Erasmus Medical Center, 3015CN Rotterdam, Netherlands
| | - Rafiquel Sarker
- From the Departments of Physiology and Medicine, Gastroenterology Division, and
| | - Mark Donowitz
- From the Departments of Physiology and Medicine, Gastroenterology Division, and
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25
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Chen T, Hubbard A, Murtazina R, Price J, Yang J, Cha B, Sarker R, Donowitz M. Myosin VI mediates the movement of NHE3 down the microvillus in intestinal epithelial cells. J Cell Sci 2014; 127:3535-45. [PMID: 24928903 PMCID: PMC4132392 DOI: 10.1242/jcs.149930] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 05/13/2014] [Indexed: 12/27/2022] Open
Abstract
The intestinal brush border Na(+)/H(+) exchanger NHE3 is tightly regulated through changes in its endocytosis and exocytosis. Myosin VI, a minus-end-directed actin motor, has been implicated in endocytosis at the inter-microvillar cleft and during vesicle remodeling in the terminal web. Here, we asked whether myosin VI also regulates NHE3 movement down the microvillus. The basal NHE3 activity and its surface amount, determined by fluorometry of the ratiometric pH indicator BCECF and biotinylation assays, respectively, were increased in myosin-VI-knockdown (KD) Caco-2/Bbe cells. Carbachol (CCH) and forskolin (FSK) stimulated NHE3 endocytosis in control but not in myosin VI KD cells. Importantly, immunoelectron microscopy results showed that NHE3 was preferentially localized in the basal half of control microvilli but in the distal half in myosin VI KD cells. Treatment with dynasore duplicated some aspects of myosin VI KD: it increased basal surface NHE3 activity and prevented FSK-induced NHE3 endocytosis. However, NHE3 had an intermediate distribution along the microvillus (between that in myosin VI KD and untreated cells) in dynasore-treated cells. We conclude that myosin VI is required for basal and stimulated endocytosis of NHE3 in intestinal cells, and suggest that myosin VI also moves NHE3 down the microvillus.
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Affiliation(s)
- Tiane Chen
- Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Ann Hubbard
- Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Rakhilya Murtazina
- Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Jennifer Price
- Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA Department of Gastroenterology, University of California, School of Medicine, San Francisco, CA 94143, USA
| | - Jianbo Yang
- Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Boyoung Cha
- Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Rafiquel Sarker
- Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Mark Donowitz
- Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA Departments of Medicine and Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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26
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Sultan A, Luo M, Yu Q, Riederer B, Xia W, Chen M, Lissner S, Gessner JE, Donowitz M, Yun CC, deJonge H, Lamprecht G, Seidler U. Differential association of the Na+/H+ Exchanger Regulatory Factor (NHERF) family of adaptor proteins with the raft- and the non-raft brush border membrane fractions of NHE3. Cell Physiol Biochem 2014; 32:1386-402. [PMID: 24297041 DOI: 10.1159/000356577] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/24/2013] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND/AIMS Trafficking, brush border membrane (BBM) retention, and signal-specific regulation of the Na+/H+ exchanger NHE3 is regulated by the Na+/H+ Exchanger Regulatory Factor (NHERF) family of PDZ-adaptor proteins, which enable the formation of multiprotein complexes. It is unclear, however, what determines signal specificity of these NHERFs. Thus, we studied the association of NHE3, NHERF1 (EBP50), NHERF2 (E3KARP), and NHERF3 (PDZK1) with lipid rafts in murine small intestinal BBM. METHODS Detergent resistant membranes ("lipid rafts") were isolated by floatation of Triton X-incubated small intestinal BBM from a variety of knockout mouse strains in an Optiprep step gradient. Acid-activated NHE3 activity was measured fluorometrically in BCECF-loaded microdissected villi, or by assessment of CO2/HCO3(-) mediated increase in fluid absorption in perfused jejunal loops of anethetized mice. RESULTS NHE3 was found to partially associate with lipid rafts in the native BBM, and NHE3 raft association had an impact on NHE3 transport activity and regulation in vivo. NHERF1, 2 and 3 were differentially distributed to rafts and non-rafts, with NHERF2 being most raft-associated and NHERF3 entirely non-raft associated. NHERF2 expression enhanced the localization of NHE3 to membrane rafts. The use of acid sphingomyelinase-deficient mice, which have altered membrane lipid as well as lipid raft composition, allowed us to test the validity of the lipid raft concept in vivo. CONCLUSIONS The differential association of the NHERFs with the raft-associated and the non-raft fraction of NHE3 in the brush border membrane is one component of the differential and signal-specific NHE3 regulation by the different NHERFs.
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27
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Yang J, Singh V, Chen TE, Sarker R, Xiong L, Cha B, Jin S, Li X, Tse CM, Zachos NC, Donowitz M. NHERF2/NHERF3 protein heterodimerization and macrocomplex formation are required for the inhibition of NHE3 activity by carbachol. J Biol Chem 2014; 289:20039-53. [PMID: 24867958 DOI: 10.1074/jbc.m114.562413] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
NHERF1, NHERF2, and NHERF3 belong to the NHERF (Na(+)/H(+) exchanger regulatory factor) family of PSD-95/Discs-large/ZO-1 (PDZ) scaffolding proteins. Individually, each NHERF protein has been shown to be involved in the regulation of multiple receptors or transporters including Na(+)/H(+) exchanger 3 (NHE3). Although NHERF dimerizations have been reported, results have been inconsistent, and the physiological function of NHERF dimerizations is still unknown. The current study semiquantitatively compared the interaction strength among all possible homodimerizations and heterodimerizations of these three NHERF proteins by pulldown and co-immunoprecipitation assays. Both methods showed that NHERF2 and NHERF3 heterodimerize as the strongest interaction among all NHERF dimerizations. In vivo NHERF2/NHERF3 heterodimerization was confirmed by FRET and FRAP (fluorescence recovery after photobleach). NHERF2/NHERF3 heterodimerization is mediated by PDZ domains of NHERF2 and the C-terminal PDZ domain recognition motif of NHERF3. The NHERF3-4A mutant is defective in heterodimerization with NHERF2 and does not support the inhibition of NHE3 by carbachol. This suggests a role for NHERF2/NHERF3 heterodimerization in the regulation of NHE3 activity. In addition, both PDZ domains of NHERF2 could be simultaneously occupied by NHERF3 and another ligand such as NHE3, α-actinin-4, and PKCα, promoting formation of NHE3 macrocomplexes. This study suggests that NHERF2/NHERF3 heterodimerization mediates the formation of NHE3 macrocomplexes, which are required for the inhibition of NHE3 activity by carbachol.
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Affiliation(s)
- Jianbo Yang
- From the Department of Medicine, Division of Gastroenterology and
| | - Varsha Singh
- From the Department of Medicine, Division of Gastroenterology and
| | - Tian-E Chen
- From the Department of Medicine, Division of Gastroenterology and
| | - Rafiquel Sarker
- From the Department of Medicine, Division of Gastroenterology and
| | - Lishou Xiong
- From the Department of Medicine, Division of Gastroenterology and
| | - Boyoung Cha
- From the Department of Medicine, Division of Gastroenterology and
| | - Shi Jin
- From the Department of Medicine, Division of Gastroenterology and
| | - Xuhang Li
- From the Department of Medicine, Division of Gastroenterology and
| | - C Ming Tse
- From the Department of Medicine, Division of Gastroenterology and
| | | | - Mark Donowitz
- From the Department of Medicine, Division of Gastroenterology and Department of Physiology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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28
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No YR, He P, Yoo BK, Yun CC. Unique regulation of human Na+/H+ exchanger 3 (NHE3) by Nedd4-2 ligase that differs from non-primate NHE3s. J Biol Chem 2014; 289:18360-72. [PMID: 24831004 DOI: 10.1074/jbc.m113.541706] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Na(+)/H(+) exchanger NHE3 expressed in the intestine and kidney plays a major role in NaCl and HCO3 (-) absorption that is closely linked to fluid absorption and blood pressure regulation. The Nedd4 family of E3 ubiquitin ligases interacts with a number of transporters and channels via PY motifs. A comparison of NHE3 sequences revealed the presence of PY motifs in NHE3s from human and several non-human primates but not in non-primate NHE3s. In this study we evaluated the differences between human and non-primate NHE3s in ubiquitination and interaction with Nedd4-2. We found that Nedd4-2 ubiquitinated human NHE3 (hNHE3) and altered its expression and activity. Surprisingly, rat NHE3 co-immunoprecipitated Nedd4-2, but its expression and activity were not altered by silencing of Nedd4-2. Ubiquitination by Nedd4-2 rendered hNHE3 to undergo internalization at a significantly greater rate than non-primate NHE3s without altering protein stability. Insertion of a PY motif in rabbit NHE3 recapitulated the interaction with Nedd4-2 and enhanced internalization. Thus, we propose a new model where disruption of Nedd4-2 interaction elevates hNHE3 expression and activity.
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Affiliation(s)
- Yi Ran No
- From the Division of Digestive Diseases, Department of Medicine and
| | - Peijian He
- From the Division of Digestive Diseases, Department of Medicine and
| | - Byong Kwon Yoo
- From the Division of Digestive Diseases, Department of Medicine and
| | - C Chris Yun
- From the Division of Digestive Diseases, Department of Medicine and Winship Cancer Institute, Emory University, Atlanta, Georgia 30322
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29
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Zachos NC, Alamelumangpuram B, Lee LJ, Wang P, Kovbasnjuk O. Carbachol-mediated endocytosis of NHE3 involves a clathrin-independent mechanism requiring lipid rafts and Cdc42. Cell Physiol Biochem 2014; 33:869-81. [PMID: 24713550 PMCID: PMC4052452 DOI: 10.1159/000358659] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/10/2014] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND In intestinal epithelial cells, acute regulation of the brush border Na(+)/H(+) exchanger, NHE3, usually occurs by changes in endocytosis and/or exocytosis. Constitutive NHE3 endocytosis involves clathrin. Carbachol (CCH), which elevates intracellular Ca(2+) ([Ca(2+)]i), decreases NHE3 activity and stimulates endocytosis; however, the mechanism involved in calcium-mediated endocytosis of NHE3 is unclear. A pool of NHE3 resides in lipid rafts, which contributes to basal, but not cAMP-mediated, NHE3 trafficking, suggesting that an alternative mechanism exists for NHE3 endocytosis. Cdc42 was demonstrated to play an integral role in some cases of cholesterol-sensitive, clathrin-independent endocytosis. Therefore, the current study was designed to test the hypotheses that (1) clathrin-mediated endocytosis (CME) is involved in constitutive, but not CCH-mediated, endocytosis of NHE3, and (2) CCH-mediated endocytosis of NHE3 occurs through a lipid raft, activated Cdc42-dependent pathway that does not involve clathrin. METHODS The role of Cdc42 and lipid rafts on NHE3 activity and endocytosis were investigated in polarized Caco-2/BBe cells using pharmacological and shRNA knockdown approaches. RESULTS Basal NHE3 activity was increased in the presence of CME blockers (chlorpromazine; K(+) depletion) supporting previous reports that constitutive NHE3 endocytosis is clathrin dependent. In contrast, CCH-inhibition of NHE3 activity was abolished in Caco-2/BBe cells treated with MβCD (to disrupt lipid rafts) as well as in Cdc42 knockdown cells but was unaffected by CME blockers. CONCLUSION CCH-mediated inhibition of NHE3 activity is not dependent on clathrin and involves lipid rafts and requires Cdc42.
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Affiliation(s)
- Nicholas C Zachos
- Department of Medicine/Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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30
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Singh V, Lin R, Yang J, Cha B, Sarker R, Tse CM, Donowitz M. AKT and GSK-3 are necessary for direct ezrin binding to NHE3 as part of a C-terminal stimulatory complex: role of a novel Ser-rich NHE3 C-terminal motif in NHE3 activity and trafficking. J Biol Chem 2014; 289:5449-61. [PMID: 24398676 DOI: 10.1074/jbc.m113.521336] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Basal activity of the BB Na(+)/H(+) exchanger NHE3 requires multiprotein complexes that form on its C terminus. One complex stimulates basal NHE3 activity and contains ezrin and phosphoinositides as major components; how it stimulates NHE3 activity is not known. This study tested the hypothesis that ezrin dynamically associates with this complex, which sets ezrin binding. NHE3 activity was reduced by an Akti. This effect was eliminated if ezrin binding to NHE3 was inhibited by a point mutant. Recombinant AKT phosphorylated NHE3 C terminus in the domain ezrin directly binds. This domain (amino acids 475-589) is predicted to be α-helical and contains a conserved cluster of three serines (Ser(515), Ser(522), and Ser(526)). Point mutations of two of these (S515A, S515D, or S526A) reduced basal NHE3 activity and surface expression and had no Akti inhibition. S526D had NHE3 activity equal to wild type with normal Akti inhibition. Ezrin binding to NHE3 was regulated by Akt, being eliminated by Akti. NHE3-S515A and -S526D did not bind ezrin; NHE3-S515D had reduced ezrin binding; NHE3-S526D bound ezrin normally. NHE3-Ser(526) is predicted to be a GSK-3 kinase phosphorylation site. A GSK-3 inhibitor reduced basal NHE3 activity as well as ezrin-NHE3 binding, and this effect was eliminated in NHE3-S526A and -S526D mutants. The conclusions were: 1) NHE3 basal activity is regulated by a signaling complex that is controlled by sequential effects of two kinases, Akt and GSK-3, which act on a Ser cluster in the same NHE3 C-terminal domain that binds ezrin; and 2) these kinases regulate the dynamic association of ezrin with NHE3 to affect basal NHE3 activity.
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Affiliation(s)
- Varsha Singh
- From the Departments of Physiology and Medicine, Gastroenterology Division, Johns, Hopkins University School of Medicine, Baltimore, Maryland 21205 and
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Armando I, Villar VAM, Jones JE, Lee H, Wang X, Asico LD, Yu P, Yang J, Escano CS, Pascua-Crusan AM, Felder RA, Jose PA. Dopamine D3 receptor inhibits the ubiquitin-specific peptidase 48 to promote NHE3 degradation. FASEB J 2013; 28:1422-34. [PMID: 24308971 DOI: 10.1096/fj.13-243840] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The dopamine D3 receptor (D3R) is crucial in the regulation of blood pressure and sodium balance, in that Drd3 gene ablation in mice results in hypertension and failure to excrete a dietary salt load. The mechanism responsible for the renal sodium retention in these mice is largely unknown. We now offer and describe a novel mechanism by which D3R decreases sodium transport in the long term by inhibiting the deubiquitinylating activity of ubiquitin-specific peptidase 48 (USP48), thereby promoting Na(+)-H(+) exchanger (NHE)-3 degradation. We found that stimulation with the D3R-specific agonist PD128907 (1 μM, 30 min) promoted the interaction and colocalization among D3R, NHE3, and USP48; inhibited USP48 activity (-35±6%, vs. vehicle), resulting in increased ubiquitinylated NHE3 (+140±10%); and decreased NHE3 expression (-50±9%) in human renal proximal tubule cells (hRPTCs). USP48 silencing decreased NHE3's half-life (USP48 siRNA t1/2=6.1 h vs. vehicle t1/2=12.9 h), whereas overexpression of USP48 increased NHE3 half-life (t1/2=21.8 h), indicating that USP48 protects NHE3 from degradation via deubiquitinylation. USP48 accounted for ∼30% of the total deubiquitinylating activity in these cells. Extending our studies in vivo, we found that pharmacologic blockade of D3R via the D3R-specific antagonist GR103691 (1 μg/kg/min, 4 d) in C57Bl/6J mice increased renal NHE3 expression (+310±15%, vs. vehicle), whereas an innovative kidney-restricted Usp48 silencing via siRNA (3 μg/d, 7 d) increased ubiquitinylated NHE3 (+250±30%, vs. controls), decreased total NHE3 (-23±2%), and lowered blood pressure (-24±2 mm Hg), compared with that in control mice that received either the vehicle or nonsilencing siRNA. Our data demonstrate a crucial role for the dynamic interaction between D3R and USP48 in the regulation of NHE3 expression and function.
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Affiliation(s)
- Ines Armando
- 2Division of Nephrology, Department of Medicine, University of Maryland School of Medicine, 20 Penn St., HSF II, Ste. S003C, Baltimore, MD, USA 21201,
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Lissner S, Hsieh CJ, Nold L, Bannert K, Bodammer P, Sultan A, Seidler U, Graeve L, Lamprecht G. The PDZ-interaction of the intestinal anion exchanger downregulated in adenoma (DRA; SLC26A3) facilitates its movement into Rab11a-positive recycling endosomes. Am J Physiol Gastrointest Liver Physiol 2013; 304:G980-90. [PMID: 23578788 DOI: 10.1152/ajpgi.00132.2012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Electroneutral NaCl absorption in the ileum and colon is mediated by downregulated in adenoma (DRA) (Cl⁻/HCO₃⁻ exchanger; SLC26A3) and Na⁺/H⁺ exchanger 3 (NHE3, SLC9A3). Surface expression of transport proteins undergoes basal and regulated recycling by endo- and exocytosis. Expression and activity of DRA in the plasma membrane depend on intact lipid rafts, phosphatidylinositol 3-kinase (PI3-kinase), and the PDZ interaction of DRA. However, it is unknown how the PDZ interaction of DRA affects its trafficking to the cell surface. Therefore, the (re)cycling pathway of DRA was investigated in HEK cells stably expressing enhanced green fluorescent protein (EGFP)-DRA or EGFP-DRA-ETKFminus (a mutant lacking the PDZ interaction motif). Early, late, and recycling endosomes were immunoisolated by precipitating stably transfected mCherry-hemagglutinin (HA)-Rab5a, -7a, or -11a. EGFP-DRA and EGFP-DRA-ETKFminus were equally present in early endosomes. In recycling endosomes, wild-type DRA was preferentially present, whereas, in late endosomes, DRA-ETKF-minus dominated. Correspondingly, EGFP-DRA colocalized with mCherry-HA-Rab11a in recycling endosomes, whereas EGFP-DRA-ETKFminus colocalized with mCherry-HA-Rab7a in late endosomes. Functionally, this different distribution was reflected by a shorter half-life of the mutant DRA. Transient expression of dominant-negative Rab11a(S25N) inhibited the activity (-17%, P < 0.05) and the cell surface expression of DRA (-30%, P < 0.05). Transient transfection of Rab4a or its dominant-negative mutant Rab4a(S22N) was without effect and thus excluded participation of the rapid recycling pathway. Taken together, the PDZ interaction of DRA facilitates its movement into Rab11a-positive recycling endosomes, from where it is inserted in the plasma membrane. A scenario emerges where specific PDZ adaptor proteins are present along several compartments of the endocytosis-recycling pathway.
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Affiliation(s)
- S Lissner
- 1st Medical Department, University of Tübingen, Tübingen, Germany
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Yang J, Singh V, Cha B, Chen TE, Sarker R, Murtazina R, Jin S, Zachos NC, Patterson GH, Tse CM, Kovbasnjuk O, Li X, Donowitz M. NHERF2 protein mobility rate is determined by a unique C-terminal domain that is also necessary for its regulation of NHE3 protein in OK cells. J Biol Chem 2013; 288:16960-16974. [PMID: 23612977 DOI: 10.1074/jbc.m113.470799] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Na(+)/H(+) exchanger regulatory factor (NHERF) proteins are a family of PSD-95/Discs-large/ZO-1 (PDZ)-scaffolding proteins, three of which (NHERFs 1-3) are localized to the brush border in kidney and intestinal epithelial cells. All NHERF proteins are involved in anchoring membrane proteins that contain PDZ recognition motifs to form multiprotein signaling complexes. In contrast to their predicted immobility, NHERF1, NHERF2, and NHERF3 were all shown by fluorescence recovery after photobleaching/confocal microscopy to be surprisingly mobile in the microvilli of the renal proximal tubule OK cell line. Their diffusion coefficients, although different among the three, were all of the same magnitude as that of the transmembrane proteins, suggesting they are all anchored in the microvilli but to different extents. NHERF3 moves faster than NHERF1, and NHERF2 moves the slowest. Several chimeras and mutants of NHERF1 and NHERF2 were made to determine which part of NHERF2 confers the slower mobility rate. Surprisingly, the slower mobility rate of NHERF2 was determined by a unique C-terminal domain, which includes a nonconserved region along with the ezrin, radixin, moesin (ERM) binding domain. Also, this C-terminal domain of NHERF2 determined its greater detergent insolubility and was necessary for the formation of larger multiprotein NHERF2 complexes. In addition, this NHERF2 domain was functionally significant in NHE3 regulation, being necessary for stimulation by lysophosphatidic acid of activity and increased mobility of NHE3, as well as necessary for inhibition of NHE3 activity by calcium ionophore 4-Br-A23187. Thus, multiple functions of NHERF2 require involvement of an additional domain in this protein.
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Affiliation(s)
- Jianbo Yang
- Department of Medicine, Division of Gastroenterology, Baltimore, Maryland 21205
| | - Varsha Singh
- Department of Medicine, Division of Gastroenterology, Baltimore, Maryland 21205
| | - Boyoung Cha
- Department of Medicine, Division of Gastroenterology, Baltimore, Maryland 21205
| | - Tian-E Chen
- Department of Medicine, Division of Gastroenterology, Baltimore, Maryland 21205
| | - Rafiquel Sarker
- Department of Medicine, Division of Gastroenterology, Baltimore, Maryland 21205
| | - Rakhilya Murtazina
- Department of Medicine, Division of Gastroenterology, Baltimore, Maryland 21205
| | - Shi Jin
- Department of Medicine, Division of Gastroenterology, Baltimore, Maryland 21205
| | - Nicholas C Zachos
- Department of Medicine, Division of Gastroenterology, Baltimore, Maryland 21205
| | - George H Patterson
- Biophotonics Section, National Institute of Biomedical Imaging and Bioengineering, NIH, Bethesda, Maryland 20892
| | - C Ming Tse
- Department of Medicine, Division of Gastroenterology, Baltimore, Maryland 21205
| | - Olga Kovbasnjuk
- Department of Medicine, Division of Gastroenterology, Baltimore, Maryland 21205
| | - Xuhang Li
- Department of Medicine, Division of Gastroenterology, Baltimore, Maryland 21205
| | - Mark Donowitz
- Department of Medicine, Division of Gastroenterology, Baltimore, Maryland 21205; Department of Physiology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
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Abstract
There is increasing evidence that G protein-coupled receptor (GPCR) signaling is regulated in lipid raft microdomains. GPCRs and GPCR-signaling molecules, including G proteins and protein kinases, have been reported to compartmentalize in these microdomains. Dopamine D(1)-like receptors (D(1)R and D(5)R) belong to a family of GPCRs that are important in the regulation of renal function. These receptors are not only localized and regulated in caveolae that contains caveolin-1 but are also distributed in non--caveolar lipid rafts which do not contain caveolin-1. This chapter describes detergent- and non-detergent-based methods to obtain lipid raft fractions from renal proximal tubule cells.
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Ares GR, Ortiz PA. Dynamin2, clathrin, and lipid rafts mediate endocytosis of the apical Na/K/2Cl cotransporter NKCC2 in thick ascending limbs. J Biol Chem 2012; 287:37824-34. [PMID: 22977238 DOI: 10.1074/jbc.m112.386425] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Steady-state surface levels of the apical Na/K/2Cl cotransporter NKCC2 regulate NaCl reabsorption by epithelial cells of the renal thick ascending limb (THAL). We reported that constitutive endocytosis of NKCC2 controls NaCl absorption in native THALs; however, the pathways involved in NKCC2 endocytosis are unknown. We hypothesized that NKCC2 endocytosis at the apical surface depends on dynamin-2 and clathrin. Measurements of steady-state surface NKCC2 and the rate of NKCC2 endocytosis in freshly isolated rat THALs showed that inhibition of endogenous dynamin-2 with dynasore blunted NKCC2 endocytosis by 56 ± 11% and increased steady-state surface NKCC2 by 67 ± 27% (p < 0.05). Expression of the dominant negative Dyn2K44A in THALs slowed the rate of NKCC2 endocytosis by 38 ± 8% and increased steady-state surface NKCC2 by 37 ± 8%, without changing total NKCC2 expression. Inhibition of clathrin-mediated endocytosis with chlorpromazine blunted NKCC2 endocytosis by 54 ± 6%, while preventing clathrin from interacting with synaptojanin also blunted NKCC2 endocytosis by 52 ± 5%. Disruption of lipid rafts blunted NKCC2 endocytosis by 39 ± 4% and silencing caveolin-1 by 29 ± 4%. Simultaneous inhibition of clathrin- and lipid raft-mediated endocytosis completely blocked NKCC2 internalization. We concluded that dynamin-2, clathrin, and lipid rafts mediate NKCC2 endocytosis and maintain steady-state apical surface NKCC2 in native THALs. These are the first data identifying the endocytic pathway for apical NKCC2 endocytosis.
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Affiliation(s)
- Gustavo R Ares
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, Wayne State University, Detroit, Michigan 48202, USA
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Narayanavari SA, Sritharan M, Haake DA, Matsunaga J. Multiple leptospiral sphingomyelinases (or are there?). MICROBIOLOGY-SGM 2012; 158:1137-1146. [PMID: 22422753 DOI: 10.1099/mic.0.057737-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Culture supernatants of leptospiral pathogens have long been known to haemolyse erythrocytes. This property is due, at least in part, to sphingomyelinase activity. Indeed, genome sequencing reveals that pathogenic Leptospira species are richly endowed with sphingomyelinase homologues: five genes have been annotated to encode sphingomyelinases in Leptospira interrogans. Such redundancy suggests that this class of genes is likely to benefit leptospiral pathogens in their interactions with the mammalian host. Surprisingly, sequence comparison with bacterial sphingomyelinases for which the crystal structures are known reveals that only one of the leptospiral homologues has the active site amino acid residues required for enzymic activity. Based on studies of other bacterial toxins, we propose that leptospiral sphingomyelinase homologues, irrespective of their catalytic activity, may possess additional molecular functions that benefit the spirochaete. Potential secretion pathways and roles in pathogenesis are discussed, including nutrient acquisition, dissemination, haemorrhage and immune evasion. Although leptospiral sphingomyelinase-like proteins are best known for their cytolytic properties, we believe that a better understanding of their biological role requires the examination of their sublytic properties as well.
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Affiliation(s)
| | - Manjula Sritharan
- Department of Animal Sciences, University of Hyderabad, Hyderabad, India
| | - David A Haake
- Department of Medicine, University of California at Los Angeles, Los Angeles, CA, USA.,Department of Urology, University of California at Los Angeles, Los Angeles, CA, USA.,Division of Infectious Diseases, VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA.,Department of Microbiology, Immunology, and Molecular Genetics, University of California at Los Angeles, Los Angeles, CA, USA
| | - James Matsunaga
- Research Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA.,Department of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
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Zizak M, Chen T, Bartonicek D, Sarker R, Zachos NC, Cha B, Kovbasnjuk O, Korac J, Mohan S, Cole R, Chen Y, Tse CM, Donowitz M. Calmodulin kinase II constitutively binds, phosphorylates, and inhibits brush border Na+/H+ exchanger 3 (NHE3) by a NHERF2 protein-dependent process. J Biol Chem 2012; 287:13442-56. [PMID: 22371496 DOI: 10.1074/jbc.m111.307256] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The epithelial brush border (BB) Na(+)/H(+) exchanger 3 (NHE3) accounts for most renal and intestinal Na(+) absorption. Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) inhibits NHE3 activity under basal conditions in intact intestine, acting in the BB, but the mechanism is unclear. We now demonstrate that in both PS120 fibroblasts and polarized Caco-2BBe cells expressing NHE3, CaMKII inhibits basal NHE3 activity, because the CaMKII-specific inhibitors KN-93 and KN-62 stimulate NHE3 activity. This inhibition requires NHERF2. CaMKIIγ associates with NHE3 between aa 586 and 605 in the NHE3 C terminus in a Ca(2+)-dependent manner, with less association when Ca(2+) is increased. CaMKII inhibits NHE3 by an effect on its turnover number, not changing surface expression. Back phosphorylation demonstrated that NHE3 is phosphorylated by CaMKII under basal conditions. This overall phosphorylation of NHE3 is not affected by the presence of NHERF2. Amino acids downstream of NHE3 aa 690 are required for CaMKII to inhibit basal NHE3 activity, and mutations of the three putative CaMKII phosphorylation sites downstream of aa 690 each prevented KN-93 stimulation of NHE3 activity. These studies demonstrate that CaMKIIγ is a novel NHE3-binding protein, and this association is reduced by elevated Ca(2+). CaMKII inhibits basal NHE3 activity associated with phosphorylation of NHE3 by effects requiring aa downstream of NHE3 aa 690 and of the CaMKII-binding site on NHE3. CaMKII binding to and phosphorylation of the NHE3 C terminus are parts of the physiologic regulation of NHE3 that occurs in fibroblasts as well as in the BB of an intestinal Na(+)-absorptive cell.
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Affiliation(s)
- Mirza Zizak
- Division of Gastroenterology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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Chen G, Howe AG, Xu G, Fröhlich O, Klein JD, Sands JM. Mature N-linked glycans facilitate UT-A1 urea transporter lipid raft compartmentalization. FASEB J 2011; 25:4531-9. [PMID: 21965602 PMCID: PMC3236619 DOI: 10.1096/fj.11-185991] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2011] [Accepted: 09/15/2011] [Indexed: 11/11/2022]
Abstract
The UT-A1 urea transporter is a glycoprotein with two different glycosylated forms of 97 and 117 kDa. In this study, we found the 117-kDa UT-A1 preferentially resides in lipid rafts, suggesting that the glycosylation status may interfere with UT-A1 lipid raft trafficking. This was confirmed by a site-directed mutagenesis study in MDCK cells. The nonglycosylated UT-A1 showed reduced localization in lipid rafts. By using sugar-specific binding lectins, we further found that the UT-A1 in nonlipid rafts contained a high amount of mannose, as detected by concanavalin A, while the UT-A1 in lipid rafts was the mature N-acetylglucosamine-containing form, as detected by wheat germ agglutinin. In the inner medulla (IM) of diabetic rats, the more abundant 117-kDa UT-A1 in lipid rafts was the mature glycosylation form, with high amounts of N-acetylglucosamine and sialic acid. In contrast, in the IM of normal rats, the predominant 97-kDa UT-A1 was the form enriched in mannose. Functionally, inhibition of glycosylation by tunicamycin or elimination of the glycosylation sites by mutation significantly reduced UT-A1 activity in oocytes. Taken together, our study reveals a new role of N-linked glycosylation in regulating UT-A1 activity by promoting UT-A1 trafficking into membrane lipid raft subdomains.
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Affiliation(s)
- Guangping Chen
- Renal Division, Department of Medicine, Emory University, Atlanta, GA 30322, USA.
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39
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Zhu X, Cha B, Zachos NC, Sarker R, Chakraborty M, Chen TE, Kovbasnjuk O, Donowitz M. Elevated calcium acutely regulates dynamic interactions of NHERF2 and NHE3 proteins in opossum kidney (OK) cell microvilli. J Biol Chem 2011; 286:34486-96. [PMID: 21799002 DOI: 10.1074/jbc.m111.230219] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The brush border (BB) Na(+)/H(+) exchanger NHE3 is rapidly activated or inhibited by changes in trafficking, which mimics renal and intestinal physiology. However, there is a paradox in that NHE3 has limited mobility in the BB due to its binding to the multi-PDZ domain containing the NHERF family. To allow increased endocytosis, as occurs with elevated intracellular Ca(2+), we hypothesized that NHE3 had to be, at least transiently, released from the BB cytoskeleton. Because NHERF1 and -2 are localized at the BB, where they bind NHE3 as well as the cytoskeleton, we tested whether either or both might dynamically interact with NHE3 as part of Ca(2+) signaling. We employed FRET to study close association of NHE3 and these NHERFs and fluorescence recovery after photobleaching to monitor NHE3 mobility in the apical domain in polarized opossum kidney cells. Under basal conditions, NHERF2 and NHE3 exhibited robust FRET signaling. Within 1 min of A23187 (0.5 μm) exposure, the NHERF2-NHE3 FRET signal was abolished, and BB NHE3 mobility was transiently increased. The dynamics in FRET signal and NHE3 mobility correlated well with a change in co-precipitation of NHE3 and NHERF2 but not NHERF1. We conclude the following. 1) Under basal conditions, NHE3 closely associates with NHERF2 in opossum kidney cell microvilli. 2) Within 1 min of elevated Ca(2+), the close association of NHE3-NHERF2 is abolished but is re-established in ∼60 min. 3) The change in NHE3-NHERF2 association is accompanied by an increased BB mobile fraction of NHE3, which contributes to inhibition of NHE3 transport activity via increased endocytosis.
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Affiliation(s)
- Xinjun Zhu
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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Lin Z, Jin S, Duan X, Wang T, Martini S, Hulamm P, Cha B, Hubbard A, Donowitz M, Guggino SE. Chloride channel (Clc)-5 is necessary for exocytic trafficking of Na+/H+ exchanger 3 (NHE3). J Biol Chem 2011; 286:22833-45. [PMID: 21561868 DOI: 10.1074/jbc.m111.224998] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
ClC-5, a chloride/proton exchanger, is predominantly expressed and localized in subapical endosomes of the renal proximal tubule. Mutations of the CLCN5 gene cause Dent disease. The symptoms of Dent disease are replicated in Clcn5 knock-out mice. Absence of ClC-5 in mice is associated with reduced surface expression of NHE3 in proximal tubules. The molecular basis for this change is not fully understood. In this study, we investigated the mechanisms by which ClC-5 regulates trafficking of NHE3. Whether ClC-5-dependent endocytosis, exocytosis, or both contributed to the altered distribution of NHE3 was examined. First, NHE3 activity in proximal tubules of wild type (WT) and Clcn5 KO mice was determined by two-photon microscopy. Basal and dexamethasone-stimulated NHE3 activity of Clcn5 KO mice was decreased compared with that seen in WT mice, whereas the degree of inhibition of NHE3 activity by increasing cellular concentration of cAMP (forskolin) or Ca(2+) (A23187) was not different in WT and Clcn5 KO mice. Second, NHE3-dependent absorption of HCO(3)(-), measured by single tubule perfusion, was reduced in proximal tubules of Clcn5 KO mice. Third, by cell surface biotinylation, trafficking of NHE3 was examined in short hairpin RNA (shRNA) plasmid-transfected opossum kidney cells. Surface NHE3 was reduced in opossum kidney cells with reduced expression of ClC-5, whereas the total protein level of NHE3 did not change. Parathyroid hormone decreased NHE3 surface expression, but the extent of decrease and the rate of endocytosis observed in both scrambled and ClC-5 knockdown cells were not significantly different. However, the rates of basal and dexamethasone-stimulated exocytosis of NHE3 were attenuated in ClC-5 knockdown cells. These results show that ClC-5 plays an essential role in exocytosis of NHE3.
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Affiliation(s)
- Zhihong Lin
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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Gildea JJ, Kemp BA, Howell NL, Van Sciver RE, Carey RM, Felder RA. Inhibition of renal caveolin-1 reduces natriuresis and produces hypertension in sodium-loaded rats. Am J Physiol Renal Physiol 2011; 300:F914-20. [PMID: 21289050 DOI: 10.1152/ajprenal.00380.2010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Renal dopamine receptor function and ion transport inhibition are impaired in essential hypertension. We recently reported that caveolin-1 (CAV1) and lipid rafts are necessary for normal D(1)-like receptor-dependent internalization of Na-K-ATPase in human proximal tubule cells. We now hypothesize that CAV1 is necessary for the regulation of urine sodium (Na(+)) excretion (U(Na)V) and mean arterial blood pressure (MAP) in vivo. Acute renal interstitial (RI) infusion into Sprague-Dawley rats of 1 μg·kg⁻¹·min⁻¹ fenoldopam (FEN; D(1)-like receptor agonist) caused a 0.46 ± 0.15-μmol/min increase in U(Na)V (over baseline of 0.29 ± 0.04 μmol/min; P < 0.01). This increase was seen in Na(+)-loaded rats, but not in those under a normal-sodium load. Coinfusion with β-methyl cyclodextrin (βMCD; lipid raft disrupter, 200 μg·kg⁻¹·min⁻¹) completely blocked this FEN-induced natriuresis (P < 0.001). Long-term (3 day) lipid raft disruption via continuous RI infusion of 80 μg·kg⁻¹·min⁻¹ βMCD decreased renal cortical CAV1 expression (47.3 ± 6.4%; P < 0.01) and increased MAP (32.4 ± 6.6 mmHg; P < 0.001) compared with vehicle-infused animals. To determine whether the MAP rise was due to a CAV1-dependent lipid raft-mediated disruption, Na(+)-loaded rats were given a bolus RI infusion of CAV1 siRNA. Two days postinfusion, cortical CAV1 expression was decreased by 73.6 ± 8.2% (P < 0.001) and the animals showed an increase in MAP by 17.4 ± 2.9 mmHg (P < 0.01) compared with animals receiving scrambled control siRNA. In summary, acute kidney-specific lipid raft disruption decreases CAV1 expression and blocks D(1)-like receptor-induced natriuresis. Furthermore, chronic disruption of lipid rafts or CAV1 protein expression in the kidney induces hypertension.
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Affiliation(s)
- John J Gildea
- Department of Pathology, The Univ. of Virginia, Charlottesville, VA 22908, USA
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Wani NA, Kaur J. Reduced levels of folate transporters (PCFT and RFC) in membrane lipid rafts result in colonic folate malabsorption in chronic alcoholism. J Cell Physiol 2011; 226:579-87. [PMID: 21069807 DOI: 10.1002/jcp.22525] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We studied the effect of chronic ethanol ingestion on folate transport across the colonic apical membranes (CAM) in rats. Male Wistar rats were fed 1 g/kg body weight/day ethanol (20%) solution orally for 3 months and folate transport was studied in the isolated colon apical membrane vesicles. The folate transport was found to be carrier mediated, saturable, with pH optima at 5.0. Chronic ethanol ingestion reduced the folate transport across the CAM by decreasing the affinity of transporters (high Km) for the substrate and by decreasing the number of transporter molecules (low Vmax) on the colon luminal surface. The decreased transport activity at the CAM was associated with down-regulation of the proton-coupled folate transporter (PCFT) and the reduced folate carrier (RFC) which resulted in decreased PCFT and RFC protein levels in the colon of rats fed alcohol chronically. Moreover, the PCFT and the RFC were found to be distributed in detergent insoluble fraction of the CAM in rats. Floatation experiments on Optiprep density gradients demonstrated the association of the PCFT and the RFC protein with lipid rafts (LR). Chronic alcoholism decreased the PCFT and the RFC protein levels in the CAM LR in accordance with the decreased synthesis. Hence, we propose that downregulation in the expression of the PCFT and the RFC in colon results in reduced levels of these transporters in colon apical membrane LR as a mechanism of folate malabsorption during chronic alcoholism.
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Affiliation(s)
- Nissar Ahmad Wani
- Department of Biochemistry, Postgraduate Institute of Medical Education and Research, Chandigarh, India
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Sarker R, Valkhoff VE, Zachos NC, Lin R, Cha B, Chen TE, Guggino S, Zizak M, de Jonge H, Hogema B, Donowitz M. NHERF1 and NHERF2 are necessary for multiple but usually separate aspects of basal and acute regulation of NHE3 activity. Am J Physiol Cell Physiol 2010; 300:C771-82. [PMID: 21191106 DOI: 10.1152/ajpcell.00119.2010] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Na(+)/H(+) exchanger 3 (NHE3) is expressed in the brush border (BB) of intestinal epithelial cells and accounts for the majority of neutral NaCl absorption. It has been shown that the Na(+)/H(+) exchanger regulatory factor (NHERF) family members of multi-PDZ domain-containing scaffold proteins bind to the NHE3 COOH terminus and play necessary roles in NHE3 regulation in intestinal epithelial cells. Most studies of NHE3 regulation have been in cell models in which NHERF1 and/or NHERF2 were overexpressed. We have now developed an intestinal Na(+) absorptive cell model in Caco-2/bbe cells by expressing hemagglutinin (HA)-tagged NHE3 with an adenoviral infection system. Roles of NHERF1 and NHERF2 in NHE3 regulation were determined, including inhibition by cAMP, cGMP, and Ca(2+) and stimulation by EGF, with knockdown (KD) approaches with lentivirus (Lenti)-short hairpin RNA (shRNA) and/or adenovirus (Adeno)-small interfering RNA (siRNA). Stable infection of Caco-2/bbe cells by NHERF1 or NHERF2 Lenti-shRNA significantly and specifically reduced NHERF protein expression by >80%. NHERF1 KD reduced basal NHE3 activity, while NHERF2 KD stimulated NHE3 activity. siRNA-mediated (transient) and Lenti-shRNA-mediated (stable) gene silencing of NHERF2 (but not of NHERF1) abolished cGMP- and Ca(2+)-dependent inhibition of NHE3. KD of NHERF1 or NHERF2 alone had no effect on cAMP inhibition of NHE3, but KD of both simultaneously abolished the effect of cAMP. The stimulatory effect of EGF on NHE3 was eliminated in NHERF1-KD but occurred normally in NHERF2-KD cells. These findings show that both NHERF2 and NHERF1 are involved in setting NHE3 activity. NHERF2 is necessary for cGMP-dependent protein kinase (cGK) II- and Ca(2+)-dependent inhibition of NHE3. cAMP-dependent inhibition of NHE3 activity requires either NHERF1 or NHERF2. Stimulation of NHE3 activity by EGF is NHERF1 dependent.
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Affiliation(s)
- Rafiquel Sarker
- Gastroenterology and Hepatology Division, Department of Medicine, Johns Hopkins Univ. School of Medicine, Baltimore, MD 21205-2195, USA
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Saksena S, Tyagi S, Goyal S, Gill RK, Alrefai WA, Ramaswamy K, Dudeja PK. Stimulation of apical Cl⁻/HCO₃⁻(OH⁻) exchanger, SLC26A3 by neuropeptide Y is lipid raft dependent. Am J Physiol Gastrointest Liver Physiol 2010; 299:G1334-43. [PMID: 20884887 PMCID: PMC3006247 DOI: 10.1152/ajpgi.00039.2010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Neuropeptide Y (NPY), an important proabsorptive hormone of the gastrointestinal tract has been shown to inhibit chloride secretion and stimulate NaCl absorption. However, mechanisms underlying the proabsorptive effects of NPY are not fully understood. The present studies were designed to examine the direct effects of NPY on apical Cl⁻/HCO₃⁻(OH⁻) exchange activity and the underlying mechanisms involved utilizing Caco2 cells. Our results showed that NPY (100 nM, 30 min) significantly increased Cl⁻/HCO₃⁻(OH⁻) exchange activity (∼2-fold). Selective NPY/Y1 or Y2 receptor agonists mimicked the effects of NPY. NPY-mediated stimulation of Cl⁻/HCO₃⁻(OH⁻) exchange activity involved the ERK1/2 MAP kinase-dependent pathway. Cell surface biotinylation studies showed that NPY does not alter DRA (apical Cl⁻/HCO₃⁻(OH⁻) exchanger) surface expression, ruling out the involvement of membrane trafficking events. Interestingly, DRA was found to be predominantly expressed in the detergent-insoluble (DI) and low-density fractions (LDF) of human colonic apical membrane vesicles (AMVs) representing lipid rafts. Depletion of membrane cholesterol by methyl-β-cyclodextrin (MβCD, 10 mM, 1 h) remarkably decreased DRA expression in the DI fractions. Similar results were obtained in Triton-X 100-treated Caco2 plasma membranes. DRA association with lipid rafts in the DI and LDF fractions of Caco2 cells was significantly enhanced (∼45%) by NPY compared with control. MβCD significantly decreased Cl⁻/HCO₃⁻(OH⁻) exchange activity in Caco2 cells as measured by DIDS- or niflumic acid-sensitive ³⁶Cl⁻ uptake (∼50%). Our results demonstrate that NPY modulates Cl⁻/HCO₃⁻(OH⁻) exchange activity by enhancing the association of DRA with lipid rafts, thereby resulting in an increase in Cl⁻/HCO₃⁻(OH⁻) exchange activity. Our findings suggest that the alteration in the association of DRA with lipid rafts may contribute to the proabsorptive effects of NPY in the human intestine.
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Affiliation(s)
- Seema Saksena
- Dept. of Medicine, University of Illinois at Chicago and Jesse Brown Veterans Affairs Medical Center, Illinois 60612, USA.
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Lissner S, Nold L, Hsieh CJ, Turner JR, Gregor M, Graeve L, Lamprecht G. Activity and PI3-kinase dependent trafficking of the intestinal anion exchanger downregulated in adenoma depend on its PDZ interaction and on lipid rafts. Am J Physiol Gastrointest Liver Physiol 2010; 299:G907-20. [PMID: 20634435 PMCID: PMC5142450 DOI: 10.1152/ajpgi.00191.2010] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The Cl/HCO(3) exchanger downregulated in adenoma (DRA) mediates electroneutral NaCl absorption in the intestine together with the apical Na/H exchanger NHE3. Lipid rafts (LR) modulate transport activity and are involved in phosphatidylinositol 3-kinase (PI3-kinase)-dependent trafficking of NHE3. Although DRA and NHE3 interact via PDZ adaptor proteins of the NHERF family, the role of LR and PDZ proteins in the regulation of DRA is unknown. We examined the association of DRA with LR using the nonionic detergent Triton X-100. DRA cofractionated with LR independently of its PDZ binding motif. Furthermore, DRA interacts with PDZK1, E3KARP, and IKEPP in LR, although their localization within lipid rafts is independent of DRA. Disruption of LR integrity resulted in the disappearance of DRA from LR, in a decrease of its surface expression and in a reduction of its activity. In HEK cells the inhibition of DRA by LR disruption was entirely dependent on the presence of the PDZ interaction motif. In addition, in Caco-2/BBE cells the inhibition by LR disruption was more pronounced in wild-type DRA than in mutated DRA (DRA-ETKFminus; lacking the PDZ binding motif)-expressing cells. Inhibition of PI3-kinase decreased the activity and the cell surface expression of wild-type DRA but not of DRA-ETKFminus; the partitioning into LR was unaffected. Furthermore, simultaneous inhibition of PI3-kinase and disruption of LR did not further decrease DRA activity and cell surface expression compared with LR disruption only. These results suggest that the activity of DRA depends on its LR association, on its PDZ interaction, and on PI3-kinase activity.
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Affiliation(s)
- S. Lissner
- 1st Medical Department, University of Tübingen, Tübingen, Germany,
| | - L. Nold
- 1st Medical Department, University of Tübingen, Tübingen, Germany,
| | - C.-J. Hsieh
- 1st Medical Department, University of Tübingen, Tübingen, Germany,
| | - J. R. Turner
- Department of Pathology, University of Chicago, Chicago, Illinois; and
| | - M. Gregor
- 1st Medical Department, University of Tübingen, Tübingen, Germany,
| | - L. Graeve
- Department of Biological Chemistry and Nutrition, University of Hohenheim, Hohenheim, Germany
| | - G. Lamprecht
- 1st Medical Department, University of Tübingen, Tübingen, Germany,
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Simonin A, Fuster D. Nedd4-1 and beta-arrestin-1 are key regulators of Na+/H+ exchanger 1 ubiquitylation, endocytosis, and function. J Biol Chem 2010; 285:38293-303. [PMID: 20855896 DOI: 10.1074/jbc.m110.115089] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The ubiquitously expressed mammalian Na(+)/H(+) exchanger 1 (NHE1) controls cell volume and pH but is also critically involved in complex biological processes like cell adhesion, cell migration, cell proliferation, and mechanosensation. Pathways controlling NHE1 turnover at the plasma membrane, however, are currently unclear. Here, we demonstrate that NHE1 undergoes ubiquitylation at the plasma membrane by a process that is unprecedented for a mammalian ion transport protein. This process requires the adapter protein β-arrestin-1 that interacts with both the E3 ubiquitin ligase Nedd4-1 and the NHE1 C terminus. Truncation of NHE1 C terminus to amino acid 550 abolishes binding to β-arrestin-1 and NHE1 ubiquitylation. Overexpression of β-arrestin-1 or of wild type but not ligase-dead Nedd4-1 increases NHE1 ubiquitylation. siRNA-mediated knock-down of Nedd4-1 or β-arrestin-1 reduces NHE1 ubiquitylation and endocytosis leading to increased NHE1 surface levels. Fibroblasts derived from β-arrestin-1 and Nedd4-1 knock-out mice show loss of NHE1 ubiquitylation, increased plasmalemmal NHE1 levels and greatly enhanced NHE1 transport compared with wild-type fibroblasts. These findings reveal Nedd4-1 and β-arrestin-1 as key regulators of NHE1 ubiquitylation, endocytosis, and function. Our data suggest a broader role for β-arrestins in the regulation of membrane ion transport proteins than currently known.
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Affiliation(s)
- Alexandre Simonin
- Department of Nephrology and Hypertension, University Hospital of Bern, Freiburgstrasse 15, 3010 Bern, Switzerland
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Mohan S, Tse CM, Gabelli SB, Sarker R, Cha B, Fahie K, Nadella M, Zachos NC, Tu-Sekine B, Raben D, Amzel LM, Donowitz M. NHE3 activity is dependent on direct phosphoinositide binding at the N terminus of its intracellular cytosolic region. J Biol Chem 2010; 285:34566-78. [PMID: 20736165 DOI: 10.1074/jbc.m110.165712] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The small intestinal BB Na(+)/H(+) antiporter NHE3 accounts for the majority of intestinal sodium and water absorption. It is highly regulated with both postprandial inhibition and stimulation sequentially occurring. Phosphatidylinositide 4,5-bisphosphate (PI(4,5)P(2)) and phosphatidylinositide 3,4,5-trisphosphate (PI(3,4,5)P(3)) binding is involved with regulation of multiple transporters. We tested the hypothesis that phosphoinositides bind NHE3 under basal conditions and are necessary for its acute regulation. His(6) proteins were made from the NHE3 C-terminal region divided into four parts as follows: F1 (amino acids 475-589), F2 (amino acids 590-667), F3 (amino acids 668-747), and F4 (amino acids 748-832) and purified by a nickel column. Mutations were made in the F1 region of NHE3 and cloned in pet30a and pcDNA3.1 vectors. PI(4,5)P(2) and PI(3,4,5)P(3) bound only to the NHE3 F1 fusion protein (amino acids 475-589) on liposomal pulldown assays. Mutations were made in the putative lipid binding region of the F1 domain and studied for alterations in lipid binding and Na(+)/H(+) exchange as follows: Y501A/R503A/K505A; F509A/R511A/R512A; R511L/R512L; R520/FR527F; and R551L/R552L. Our results indicate the following. 1) The F1 domain of the NHE3 C terminus has phosphoinositide binding regions. 2) Mutations of these regions alter PI(4,5)P(2) and PI(3,4,5)P(3) binding and basal NHE3 activity. 3) The magnitude of serum stimulation of NHE3 correlates with PI(4,5)P(2) and PI(3,4,5)P(3) binding of NHE3. 4) Wortmannin inhibition of PI3K did not correlate with PI(4,5)P(2) or PI(3,4,5)P(3) binding of NHE3. Two functionally distinct phosphoinositide binding regions (Tyr(501)-Arg(512) and Arg(520)-Arg(552)) are present in the NHE3 F1 domain; both regions are important for serum stimulation, but they display differences in phosphoinositide binding, and the latter but not the former alters NHE3 surface expression.
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Affiliation(s)
- Sachin Mohan
- Department of Physiology and Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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48
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Harada K, Fukuda E, Hirohashi N, Chiba K. Regulation of intracellular pH by p90Rsk-dependent activation of an Na(+)/H(+) exchanger in starfish oocytes. J Biol Chem 2010; 285:24044-54. [PMID: 20507995 DOI: 10.1074/jbc.m109.072553] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Starfish oocytes arrest at metaphase of the first meiotic division (MI arrest) in the ovary and resume meiosis after spawning into seawater. MI arrest is maintained by lower intracellular pH (pH(i)) and release from arrest by cellular alkalization. To elucidate pH(i) regulation in oocytes, we cloned the starfish (Asterina pectinifera) Na(+)/H(+) exchanger 3 (ApNHE3) expressed in the plasma membrane of oocytes. The cytoplasmic domain of ApNHE3 contains p90 ribosomal S6 kinase (p90Rsk) phosphorylation sites, and injection of a constitutively active p90Rsk and the upstream regulator Mos to immature oocytes, stimulated an increase in pH(i). This increase was blocked by 5-(N-ethyl-N-isopropyl)-amiloride, a NHE inhibitor, and SL0101, a specific Rsk inhibitor. The MAPK kinase (MEK) inhibitor U0126 blocked the Mos-induced, but not the p90Rsk-induced, pH(i) increase, suggesting that the Mos-MEK-MAPK-p90Rsk pathway promotes ApNHE3 activation. In a cell-free extract, the Mos-MEK-MAPK-p90Rsk pathway phosphorylates ApNHE3 at Ser-590, -606, and -673. When p90Rsk-dependent ApNHE3 phosphorylation was blocked by a dominant-negative C-terminal fragment, or neutralizing antibody, the p90Rsk-induced pH(i) increase was suppressed in immature oocytes. However, ApNHE3 is up-regulated via the upstream phosphatidylinositol 3-kinase pathway before MAPK activation and the active state is maintained until spawning, suggesting that the p90Rsk-dependent ApNHE3 phosphorylation is unlikely to be the primary regulatory mechanism involved in MI arrest exit. After meiosis is completed, unfertilized eggs maintain their elevated pH(i) ( approximately 7.4) until the onset of apoptosis. We suggest that the p90Rsk/ApNHE3-dependent elevation of pH(i) increases fertilization success by delaying apoptosis initiation.
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Affiliation(s)
- Kaori Harada
- Department of Biology, Graduate School of Humanities and Sciences, Ochanomizu University, Bunkyo-ku, Tokyo 112-8610, Japan
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Errasti-Murugarren E, Molina-Arcas M, Casado FJ, Pastor-Anglada M. The human concentrative nucleoside transporter-3 C602R variant shows impaired sorting to lipid rafts and altered specificity for nucleoside-derived drugs. Mol Pharmacol 2010; 78:157-65. [PMID: 20421346 DOI: 10.1124/mol.110.063552] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The human concentrative nucleoside transporter-3 C602R (hCNT3C602R), a recently identified human concentrative nucleoside transporter-3 (hCNT3) variant, has been shown to interact with natural nucleosides with apparent K(m) values similar to those of the wild-type transporter, although binding of one of the two sodium ions required for nucleoside translocation is impaired, resulting in decreased V(max) values (Mol Pharmacol 73:379-386, 2008). We have further analyzed the properties of this hCNT3 variant by determining its localization in plasma membrane lipid domains and its interaction with nucleoside-derived drugs used in anticancer and antiviral therapies. When expressed heterologously in HeLa cells, wild-type hCNT3 localized to both lipid raft and nonlipid raft domains. Treatment of cells with the cholesterol-depleting agent methyl-beta-cyclodextrin resulted in a marked decrease in hCNT3-related transport activity that was associated with the loss of wild-type hCNT3 from lipid rafts. It is noteworthy that although exogenously expressed hCNT3C602R was present in nonlipid raft domains at a level similar to that of the wild-type transporter, the mutant transporter was present at much lower amounts in lipid rafts. A substrate profile analysis showed that interactions with a variety of nucleoside-derived drugs were altered in the hCNT3C602R variant and revealed that sugar hydroxyl residues are key structural determinants for substrate recognition by the hCNT3C602R variant.
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Affiliation(s)
- Ekaitz Errasti-Murugarren
- Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona and CIBER EHD, Avda Diagonal 645, Edifici annex, Planta-1, 08028 Barcelona, Spain
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Mechanisms of the regulation of the intestinal Na+/H+ exchanger NHE3. J Biomed Biotechnol 2010; 2010:238080. [PMID: 20011065 PMCID: PMC2789519 DOI: 10.1155/2010/238080] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2009] [Accepted: 09/11/2009] [Indexed: 01/25/2023] Open
Abstract
A major of Na+ absorptive process in the proximal part of intestine and kidney is electroneutral exchange of Na+ and H+ by Na+/H+ exchanger type 3 (NHE3). During the past decade, significant advance has been achieved in the mechanisms of NHE3 regulation. A bulk of the current knowledge on Na+/H+ exchanger regulation is based on heterologous expression of mammalian Na+/H+ exchangers in Na+/H+ exchanger deficient fibroblasts, renal epithelial, and intestinal epithelial cells. Based on the reductionist's approach, an understanding of NHE3 regulation has been greatly advanced. More recently, confirmations of in vitro studies have been made using animals deficient in one or more proteins but in some cases unexpected findings have emerged. The purpose of this paper is to provide a brief overview of recent progress in the regulation and functions of NHE3 present in the luminal membrane of the intestinal tract.
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