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Zhang S, Wang J, Liu X, Kan Z, Zhang Y, Niu Z, Hu X, Zhang L, Zhang X, Song Z. Pemetrexed alleviates piglet diarrhea by blocking the interaction between porcine epidemic diarrhea virus nucleocapsid protein and Ezrin. J Virol 2024; 98:e0162523. [PMID: 38084960 PMCID: PMC10804979 DOI: 10.1128/jvi.01625-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Accepted: 11/27/2023] [Indexed: 01/24/2024] Open
Abstract
Porcine epidemic diarrhea virus (PEDV) is an enteric coronavirus that causes high mortality in piglets, thus posing a serious threat to the world pig industry. Porcine epidemic diarrhea (PED) is related to the imbalance of sodium absorption by small intestinal epithelial cells; however, the etiology of sodium imbalanced diarrhea caused by PEDV remains unclear. Herein, we first proved that PEDV can cause a significant decrease in Na+/H+ exchanger 3 (NHE3) expression on the cell membrane, in a viral dose-dependent manner. Further study showed that the PEDV nucleocapsid (N) protein participates in the regulation of NHE3 activity through interacting with Ezrin. Flame atomic absorption spectroscopy results indicated a serious imbalance in Na+ concentration inside and outside cells following overexpression of PEDV N. Meanwhile, molecular docking technology identified that the small molecule drug Pemetrexed acts on the PEDV N-Ezrin interaction region. It was confirmed that Pemetrexed can alleviate the imbalanced Na+ concentration in IPEC-J2 cells and the diarrhea symptoms of Rongchang pigs caused by PEDV infection. Overall, our data suggest that the interaction between PEDV N and Ezrin reduces the level of phosphorylated Ezrin, resulting in a decrease in the amount of NHE3 protein on the cell membrane. This leads to an imbalance of intracellular and extracellular Na+, which causes diarrhea symptoms in piglets. Pemetrexed is effective in relieving diarrhea caused by PEDV. Our results provide a reference to screen for anti-PEDV targets and to develop drugs to prevent PED.IMPORTANCEPorcine epidemic diarrhea (PED) has caused significant economic losses to the pig industry since its initial outbreak, and the pathogenic mechanism of porcine epidemic diarrhea virus (PEDV) is still under investigation. Herein, we found that the PEDV nucleocapsid protein interacts with Ezrin to regulate Na+/H+ exchanger 3 activity. In addition, we screened out Pemetrexed, a small molecule drug, which can effectively alleviate pig diarrhea caused by PEDV. These results provide support for further exploration of the pathogenesis of PEDV and the development of drugs to prevent PED.
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Affiliation(s)
- Shujuan Zhang
- College of Veterinary Medicine, Southwest University, Chongqing, China
| | - Jing Wang
- College of Veterinary Medicine, Southwest University, Chongqing, China
| | - Xiangyang Liu
- College of Veterinary Medicine, Southwest University, Chongqing, China
- College of Veterinary Medicine, Xinjiang Agricultural University, Ürümqi, China
| | - Zifei Kan
- College of Veterinary Medicine, Southwest University, Chongqing, China
- School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Yiling Zhang
- College of Veterinary Medicine, Southwest University, Chongqing, China
- College of Animal Science and Technology, Chongqing Three Gorges Vocational College, Chongqing, China
| | - Zheng Niu
- College of Veterinary Medicine, Southwest University, Chongqing, China
- College of Veterinary Medicine, Northwest A and F University, Shanxi, China
| | - Xia Hu
- College of Veterinary Medicine, Southwest University, Chongqing, China
| | - Li Zhang
- College of Veterinary Medicine, Southwest University, Chongqing, China
| | - Xingcui Zhang
- 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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Tanaka C, Kobori T, Tameishi M, Urashima Y, Ito T, Obata T. Ezrin Modulates the Cell Surface Expression of Programmed Cell Death Ligand-1 in Human Cervical Adenocarcinoma Cells. Molecules 2021; 26:5648. [PMID: 34577118 PMCID: PMC8469114 DOI: 10.3390/molecules26185648] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 09/03/2021] [Accepted: 09/15/2021] [Indexed: 01/01/2023] Open
Abstract
Cancer cells employ programmed cell death ligand-1 (PD-L1), an immune checkpoint protein that binds to programmed cell death-1 (PD-1) and is highly expressed in various cancers, including cervical carcinoma, to abolish T-cell-mediated immunosurveillance. Despite a key role of PD-L1 in various cancer cell types, the regulatory mechanism for PD-L1 expression is largely unknown. Understanding this mechanism could provide a novel strategy for cervical cancer therapy. Here, we investigated the influence of ezrin/radixin/moesin (ERM) family scaffold proteins, crosslinking the actin cytoskeleton and certain plasma membrane proteins, on the expression of PD-L1 in HeLa cells. Our results showed that all proteins were expressed at mRNA and protein levels and that all ERM proteins were highly colocalized with PD-L1 in the plasma membrane. Interestingly, immunoprecipitation assay results demonstrated that PD-L1 interacted with ERM as well as actin cytoskeleton proteins. Furthermore, gene silencing of ezrin, but not radixin and moesin, remarkably decreased the protein expression of PD-L1 without affecting its mRNA expression. In conclusion, ezrin may function as a scaffold protein for PD-L1; regulate PD-L1 protein expression, possibly via post-translational modification in HeLa cells; and serve as a potential therapeutic target for cervical cancer, improving the current immune checkpoint blockade therapy.
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Affiliation(s)
- Chihiro Tanaka
- Laboratory of Clinical Pharmaceutics, Faculty of Pharmacy, Osaka Ohtani University, Tondabayashi 584-8540, Osaka, Japan; (C.T.); (M.T.); (Y.U.)
| | - Takuro Kobori
- Laboratory of Clinical Pharmaceutics, Faculty of Pharmacy, Osaka Ohtani University, Tondabayashi 584-8540, Osaka, Japan; (C.T.); (M.T.); (Y.U.)
| | - Mayuka Tameishi
- Laboratory of Clinical Pharmaceutics, Faculty of Pharmacy, Osaka Ohtani University, Tondabayashi 584-8540, Osaka, Japan; (C.T.); (M.T.); (Y.U.)
| | - Yoko Urashima
- Laboratory of Clinical Pharmaceutics, Faculty of Pharmacy, Osaka Ohtani University, Tondabayashi 584-8540, Osaka, Japan; (C.T.); (M.T.); (Y.U.)
| | - Takuya Ito
- Laboratory of Natural Medicines, Faculty of Pharmacy, Osaka Ohtani University, Tondabayashi 584-8540, Osaka, Japan;
| | - Tokio Obata
- Laboratory of Clinical Pharmaceutics, Faculty of Pharmacy, Osaka Ohtani University, Tondabayashi 584-8540, Osaka, Japan; (C.T.); (M.T.); (Y.U.)
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Chen Y, Wu S, Qi L, Dai W, Tian Y, Kong J. Altered absorptive function in the gall bladder during cholesterol gallstone formation is associated with abnormal NHE3 complex formation. J Physiol Biochem 2020; 76:427-435. [PMID: 32557227 DOI: 10.1007/s13105-020-00751-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 06/04/2020] [Indexed: 02/06/2023]
Abstract
Dysfunction of the Na+/H+ exchanger 3 (NHE3) contributes to the formation of cholesterol gallstones. We aimed to investigate whether NHE3 dysfunction is associated with abnormalities in NHE3 complex formation. We fed C57BL/6 mice with control or lithogenic diet and study the expression of NHE3, ezrin, and Na+/H+ exchanger regulatory factor 1 (NHERF1) in the gallbladder (GB) using RT-PCR and western blot. Immunofluorescence and immunoprecipitation were performed to investigate the interactions of NHE3 with ezrin or NHERF1. To explore the initiating factor that leads to NHE3 dysfunction, we stimulated cholangiocarcinoma cells with taurochenodeoxycholate (TCDC) and/or forskolin. The effects of TCDC on the expression of NHE3 regulatory proteins, as well as their bindings to NHE3, were detected by western blot and immunoprecipitation. Enzyme-linked immunosorbent assay was used to study the regulation of cAMP production by TCDC. The expression of NHERF1 and ezrin phosphorylation level were increased in the gallbladder epithelial cells (GBECs) of C57BL/6 mice with cholesterol gallstones. Immunofluorescence studies demonstrated that the subcellular localization of ezrin and NHERF1 were similar to that of NHE3 in GBECs. Immunoprecipitation revealed that ezrin formed macrocomplex with NHE3, which were enhanced after gallstone formation. TCDC increased forskolin-induced cAMP accumulation, and NHERF1 and PKCα expression in cholangiocarcinoma cells. Under the synergistic effect of forskolin, TCDC stimulated ezrin phosphorylation, with enhanced interaction between ezrin and NHE3. The formation of cholesterol gallstones is associated with abnormal formation of NHE3 complexes. Decreased biliary TCDC may be an initiating factor that leads to abnormal GB absorption.
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Affiliation(s)
- Yongsheng Chen
- Department of General Surgery, Shengjing Hospital of China Medical University, No. 36, San Hao Street, Heping District, Shenyang, 110004, Liaoning Province, China
| | - Shuodong Wu
- Department of General Surgery, Shengjing Hospital of China Medical University, No. 36, San Hao Street, Heping District, Shenyang, 110004, Liaoning Province, China.
| | - Li Qi
- Department of Rheumatology and Immunology, Shengjing Hospital of China Medical University, No. 39, Hua xiang Road, Tiexi District, Shenyang, 110022, Liaoning Province, China
| | - Wanlin Dai
- China Medical University, No. 77, Pu He Road, Shenbeixin District, Shenyang, 110004, Liaoning Province, China
| | - Yu Tian
- Department of General Surgery, Shengjing Hospital of China Medical University, No. 36, San Hao Street, Heping District, Shenyang, 110004, Liaoning Province, China
| | - Jing Kong
- Department of General Surgery, Shengjing Hospital of China Medical University, No. 36, San Hao Street, Heping District, Shenyang, 110004, Liaoning Province, China
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Chen T, Lin R, Avula L, Sarker R, Yang J, Cha B, Tse CM, McNamara G, Seidler U, Waldman S, Snook A, Bijvelds MJC, de Jonge HR, Li X, Donowitz M. NHERF3 is necessary for Escherichia coli heat-stable enterotoxin-induced inhibition of NHE3: differences in signaling in mouse small intestine and Caco-2 cells. Am J Physiol Cell Physiol 2019; 317:C737-C748. [PMID: 31365292 DOI: 10.1152/ajpcell.00351.2018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Enterotoxigenic Escherichia coli (ETEC) is a leading cause of childhood death from diarrhea and the leading cause of Traveler's diarrhea. E. coli heat-stable enterotoxin (ST) is a major virulence factor of ETEC and inhibits the brush border Na/H exchanger NHE3 in producing diarrhea. NHE3 regulation involves multiprotein signaling complexes that form on its COOH terminus. In this study, the hypothesis was tested that ST signals via members of the Na/H exchanger regulatory factor (NHERF) family of scaffolding proteins, NHERF2, which had been previously shown to have a role, and now with concentration on a role for NHERF3. Two models were used: mouse small intestine and Caco-2/BBe cells. In both models, ST rapidly increased intracellular cGMP, inhibited NHE3 activity, and caused a quantitatively similar decrease in apical expression of NHE3. The transport effects were NHERF3 and NHERF2 dependent. Also, mutation of the COOH-terminal amino acids of NHERF3 supported that NHERF3-NHERF2 heterodimerization was likely to account for this dual dependence. The ST increase in cGMP in both models was partially dependent on NHERF3. The intracellular signaling pathways by which ST-cGMP inhibits NHE3 were different in mouse jejunum (activation of cGMP kinase II, cGKII) and Caco-2 cells, which do not express cGKII (elevation of intracellular Ca2+ concentration [Ca2+]i). The ST elevation of [Ca2+]i was from intracellular stores and was dependent on NHERF3-NHERF2. This study shows that intracellular signaling in the same diarrheal model in multiple cell types may be different; this has implications for therapeutic strategies, which often assume that models have similar signaling mechanisms.
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Affiliation(s)
- Tiane Chen
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Ruxian Lin
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Leela Avula
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Rafiquel Sarker
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Jianbo Yang
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Boyoung Cha
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Chung Ming Tse
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - George McNamara
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Ursula Seidler
- Department of Gastroenterology, Hannover Medical School, Hannover, Germany
| | - Scott Waldman
- Division of Clinical Pharmacology, Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Adam Snook
- Division of Clinical Pharmacology, Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Marcel J C Bijvelds
- Department of Gastroenterology and Hepatology, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Hugo R de Jonge
- Department of Gastroenterology and Hepatology, Erasmus MC University Medical Center, Rotterdam, The Netherlands
| | - Xuhang Li
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Mark Donowitz
- Departments of Physiology and Medicine, Gastroenterology Division, Johns Hopkins University School of Medicine, Baltimore, Maryland
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Moulick A, Heger Z, Milosavljevic V, Richtera L, Barroso-Flores J, Merlos Rodrigo MA, Buchtelova H, Podgajny R, Hynek D, Kopel P, Adam V. Real-Time Visualization of Cell Membrane Damage Using Gadolinium-Schiff Base Complex-Doped Quantum Dots. ACS APPLIED MATERIALS & INTERFACES 2018; 10:35859-35868. [PMID: 30264566 DOI: 10.1021/acsami.8b15868] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Despite the importance of cell membranes for maintenance of integrity of cellular structures, there is still a lack of methods that allow simple real-time visualization of their damage. Herein, we describe gadolinium-Schiff base-doped quantum dots (GdQDs)-based probes for a fast facile spatial labeling of membrane injuries. We found that GdQDs preferentially interact through electron-rich and hydrophobic residues with a specific sequence motif of NHE-RF2 scaffold protein, exposed upon membrane damage. Such interaction results in a fast formation of intensively fluorescent droplets with a higher resolution and in a much shorter time compared to immunofluorescence using organic dye. GdQDs have high stability, brightness, and considerable cytocompatibility, which enable their use in long-term experiments in living cultures. To the best of our knowledge, this is the first report, demonstrating a method allowing real-time monitoring of membrane damage and recovery without any special requirements for instrumentation. Because of intensive brightness and simple signal pattern, GdQDs allow easy examination of interactions between cellular membranes and cell-penetrating peptides or cytostatic drugs. We anticipate that the simple and flexible method will also facilitate the studies dealing with host-pathogen interactions.
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Affiliation(s)
- Amitava Moulick
- Department of Chemistry and Biochemistry , Mendel University in Brno , Zemedelska 1 , CZ-613 00 Brno , Czech Republic
- Central European Institute of Technology , Brno University of Technology , Purkynova 123 , CZ-612 00 Brno , Czech Republic
| | - Zbynek Heger
- Department of Chemistry and Biochemistry , Mendel University in Brno , Zemedelska 1 , CZ-613 00 Brno , Czech Republic
- Central European Institute of Technology , Brno University of Technology , Purkynova 123 , CZ-612 00 Brno , Czech Republic
| | - Vedran Milosavljevic
- Department of Chemistry and Biochemistry , Mendel University in Brno , Zemedelska 1 , CZ-613 00 Brno , Czech Republic
| | - Lukas Richtera
- Department of Chemistry and Biochemistry , Mendel University in Brno , Zemedelska 1 , CZ-613 00 Brno , Czech Republic
- Central European Institute of Technology , Brno University of Technology , Purkynova 123 , CZ-612 00 Brno , Czech Republic
| | - Joaquin Barroso-Flores
- Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM , Carretera Toluca-Atlacomulco Km 14.5, Unidad San Cayetano , CP-50200 Toluca , Estado de México , Mexico
| | - Miguel Angel Merlos Rodrigo
- Department of Chemistry and Biochemistry , Mendel University in Brno , Zemedelska 1 , CZ-613 00 Brno , Czech Republic
- Central European Institute of Technology , Brno University of Technology , Purkynova 123 , CZ-612 00 Brno , Czech Republic
| | - Hana Buchtelova
- Department of Chemistry and Biochemistry , Mendel University in Brno , Zemedelska 1 , CZ-613 00 Brno , Czech Republic
| | - Robert Podgajny
- Faculty of Chemistry , Jagiellonian University , Gronostajowa 2 , PL 30-387 Krakow , Poland
| | - David Hynek
- Department of Chemistry and Biochemistry , Mendel University in Brno , Zemedelska 1 , CZ-613 00 Brno , Czech Republic
- Central European Institute of Technology , Brno University of Technology , Purkynova 123 , CZ-612 00 Brno , Czech Republic
| | - Pavel Kopel
- Department of Chemistry and Biochemistry , Mendel University in Brno , Zemedelska 1 , CZ-613 00 Brno , Czech Republic
- Central European Institute of Technology , Brno University of Technology , Purkynova 123 , CZ-612 00 Brno , Czech Republic
| | - Vojtech Adam
- Department of Chemistry and Biochemistry , Mendel University in Brno , Zemedelska 1 , CZ-613 00 Brno , Czech Republic
- Central European Institute of Technology , Brno University of Technology , Purkynova 123 , CZ-612 00 Brno , Czech Republic
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Li J, He Q, Li Q, Huang R, Wei X, Pan X, Wu W. Decreased expression of Na+-H+ exchanger isoforms 1 and 3 in denervated spontaneously hypertensive rat kidney. Clin Exp Hypertens 2018; 41:235-243. [PMID: 29787310 DOI: 10.1080/10641963.2018.1469639] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Jianling Li
- Department of Cardiology, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Qiaoling He
- Department of Pharmacology, Affiliated Hospital of Guangxi Medical University, The First people’s Hospital of Nanning, Nanning, China
| | - Qingjie Li
- Department of Cardiology, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Rongjie Huang
- Department of Pharmacology, Affiliated Hospital of Guangxi Medical University, The First people’s Hospital of Nanning, Nanning, China
| | - Xiaoyan Wei
- Department of Pharmacology, Affiliated Hospital of Guangxi Medical University, The First people’s Hospital of Nanning, Nanning, China
| | - Xiaofeng Pan
- Department of Cardiology, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Weifeng Wu
- Department of Cardiology, First Affiliated Hospital of Guangxi Medical University, Nanning, China
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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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Yin J, Tse CM, Cha B, Sarker R, Zhu XC, Walentinsson A, Greasley PJ, Donowitz M. A common NHE3 single-nucleotide polymorphism has normal function and sensitivity to regulatory ligands. Am J Physiol Gastrointest Liver Physiol 2017; 313:G129-G137. [PMID: 28495802 PMCID: PMC5582881 DOI: 10.1152/ajpgi.00044.2017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 05/01/2017] [Accepted: 05/05/2017] [Indexed: 01/31/2023]
Abstract
Na+/H+ exchanger NHE3 mediates the majority of intestinal and renal electroneutral sodium absorption. Dysfunction of NHE3 is associated with a variety of diarrheal diseases. We previously reported that the NHE3 gene (SLC9A3) has more than 400 single-nucleotide polymorphisms (SNPs) but few nonsynonymous polymorphisms. Among the latter, one polymorphism (rs2247114-G>A), which causes a substitution from arginine to cysteine at amino acid position 799 (p.R799C), is common in Asian populations. To improve our understanding of the population distribution and potential clinical significance of the NHE3-799C variant, we investigated the frequency of this polymorphism in different ethnic groups using bioinformatics analyses and in a cohort of Japanese patients with cardiovascular or renal disease. We also characterized the function of human NHE3-799C and its sensitivity to regulatory ligands in an in vitro model. NHE3-799C had an allele frequency of 29.5-57.6% in Asian populations, 11.1-23.6% in European populations, and 10.2-22.7% in African populations. PS120/FLAG-NHERF2 fibroblasts stably expressing NHE3-799C had lower total protein expression but a higher percentage of surface expression than those expressing NHE3-799R. NHE3-799C had similar basal activity to NHE3-799R and was similarly stimulated or inhibited, by serum or forskolin, respectively. Tenapanor, a small-molecule NHE3 inhibitor, dose-dependently inhibited NHE3-799R and NHE3-799C activities. The IC50 values of tenapanor for NHE3-799C and NHE3-799R were significantly different, but both were in the nanomolar range. These results suggest that NHE3-799C is a common variant enriched in Asian populations, is not associated with compromised function or abnormal regulation, and is unlikely to contribute to clinical disease.NEW & NOTEWORTHY This study reports results on the functional significance of human NHE3-799C under basal conditions and in response to regulatory ligands, including a novel NHE3 inhibitor called tenapanor. We demonstrate that NHE3-799C is a common variant of NHE3 that is enriched in Asian populations; however, in contrast to our previous studies using rabbit NHE3, its presence seems to have limited clinical significance in humans and is not associated with compromised function or abnormal transport regulation.
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Affiliation(s)
- Jianyi Yin
- 1Department of Medicine, Division of Gastroenterology, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| | - Chung-Ming Tse
- 1Department of Medicine, Division of Gastroenterology, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| | - Boyoung Cha
- 1Department of Medicine, Division of Gastroenterology, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| | - Rafiquel Sarker
- 1Department of Medicine, Division of Gastroenterology, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| | - Xinjun C. Zhu
- 2Department of Medicine, Division of Gastroenterology and Hepatology, Albany Medical College, Albany, New York; and
| | | | | | - Mark Donowitz
- Department of Medicine, Division of Gastroenterology, Johns Hopkins University School of Medicine, Baltimore, Maryland;
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