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Brunner N, Stein L, Amasheh S. Cellular Distribution Pattern of tjp1 (ZO-1) in Xenopus laevis Oocytes Heterologously Expressing Claudins. J Membr Biol 2023; 256:51-61. [PMID: 35737002 PMCID: PMC9884258 DOI: 10.1007/s00232-022-00251-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 06/02/2022] [Indexed: 02/07/2023]
Abstract
Epithelial barriers constitute a fundamental requirement in every organism, as they allow the separation of different environments and set boundaries against noxious and other adverse effectors. In many inflammatory and degenerative diseases, epithelial barrier function is impaired because of a disturbance of the paracellular seal. Recently, the Xenopus laevis oocyte has been established as a heterologous expression model for the analysis of transmembrane tight junction protein interactions and is currently considered to be a suitable screening model for barrier effectors. A prerequisite for this application is a physiological anchoring of claudins to the cytoskeleton via the major scaffolding protein tjp1 (tight junction protein 1, ZO-1). We have analyzed the oocyte model with regard to the interaction of heterologously expressed claudins and tjp1. Our experiments have revealed endogenous tjp1 expression in protein and mRNA analyses of unfertilized Xenopus laevis oocytes expressing human claudin 1 (CLDN1) to claudin 5 (CLDN5). The amphibian cell model can therefore be used for the analysis of claudin interactions.
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Affiliation(s)
- Nora Brunner
- Institute of Veterinary Physiology, Freie Universität Berlin, Oertzenweg 19b, 14163 Berlin, Germany
| | - Laura Stein
- Institute of Veterinary Physiology, Freie Universität Berlin, Oertzenweg 19b, 14163 Berlin, Germany
| | - Salah Amasheh
- Institute of Veterinary Physiology, Freie Universität Berlin, Oertzenweg 19b, 14163 Berlin, Germany
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Palma AG, Kotsias BA. The Effect of Dynasore Upon the Negative Interaction Between ENaC and CFTR Channels in Xenopus laevis Oocytes. J Membr Biol 2022; 255:61-69. [DOI: 10.1007/s00232-021-00212-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Accepted: 12/22/2021] [Indexed: 11/29/2022]
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Palma AG, Galizia L, Kotsias BA, Marino GI. CFTR channel in oocytes from Xenopus laevis and its regulation by xShroom1 protein. Pflugers Arch 2016; 468:871-80. [PMID: 26888038 DOI: 10.1007/s00424-016-1800-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 01/18/2016] [Accepted: 02/10/2016] [Indexed: 01/24/2023]
Abstract
Shroom is a family of related proteins linked to the actin cytoskeleton. xShroom1 is constitutively expressed in Xenopus laevis oocytes, and it is required for the expression of the epithelial sodium channel (ENaC). As there is a close relationship between ENaC and the cystic fibrosis transmembrane regulator (CFTR), we examined the action of xShroom1 on CFTR expression and activity. Biotinylation was used to measure CFTR surface expression, and currents were registered with voltage clamp when stimulated with forskolin and 3-isobutyl-1-methylxanthine. Oocytes were coinjected with CFTR complementary RNAs (cRNAs) and xShroom1 sense or antisense oligonucleotides. We observed an increment in CFTR currents and CFTR surface expression in oocytes coinjected with CFTR and xShroom1 antisense oligonucleotides. MG-132, a proteasome inhibitor, did not prevent the increment in currents when xShroom1 was suppressed by antisense oligonucleotides. In addition, we inhibited the delivery of newly synthesized proteins to the plasma membrane with BFA and we found that the half-life of plasma membrane CFTR was prolonged when coinjected with the xShroom1 antisense oligonucleotides. Chloroquine, an inhibitor of the late endosome/lysosome, did not significantly increase CFTR currents when xShroom1 expression was inhibited. The higher expression of CFTR when xShroom1 is suppressed is in concordance with the functional studies suggesting that the suppression of the xShroom1 protein resulted in an increment in CFTR currents by promoting the increase of the half-life of CFTR in the plasma membrane. The role of xShroom1 in regulating CFTR expression could be relevant in the understanding of the channel malfunction in several diseases.
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Affiliation(s)
- Alejandra G Palma
- Laboratorio de Canales Iónicos, Instituto de Investigaciones Médicas Alfredo Lanari, Universidad de Buenos Aires, IDIM-CONICET, C. de Malvinas 3150, 1427, Buenos Aires, Argentina
| | - Luciano Galizia
- Laboratorio de Canales Iónicos, Instituto de Investigaciones Médicas Alfredo Lanari, Universidad de Buenos Aires, IDIM-CONICET, C. de Malvinas 3150, 1427, Buenos Aires, Argentina
| | - Basilio A Kotsias
- Laboratorio de Canales Iónicos, Instituto de Investigaciones Médicas Alfredo Lanari, Universidad de Buenos Aires, IDIM-CONICET, C. de Malvinas 3150, 1427, Buenos Aires, Argentina
| | - Gabriela I Marino
- Laboratorio de Canales Iónicos, Instituto de Investigaciones Médicas Alfredo Lanari, Universidad de Buenos Aires, IDIM-CONICET, C. de Malvinas 3150, 1427, Buenos Aires, Argentina.
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Das D, Zalewski JK, Mohan S, Plageman TF, VanDemark AP, Hildebrand JD. The interaction between Shroom3 and Rho-kinase is required for neural tube morphogenesis in mice. Biol Open 2014; 3:850-60. [PMID: 25171888 PMCID: PMC4163662 DOI: 10.1242/bio.20147450] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Shroom3 is an actin-associated regulator of cell morphology that is required for neural tube closure, formation of the lens placode, and gut morphogenesis in mice and has been linked to chronic kidney disease and directional heart looping in humans. Numerous studies have shown that Shroom3 likely regulates these developmental processes by directly binding to Rho-kinase and facilitating the assembly of apically positioned contractile actomyosin networks. We have characterized the molecular basis for the neural tube defects caused by an ENU-induced mutation that results in an arginine-to-cysteine amino acid substitution at position 1838 of mouse Shroom3. We show that this substitution has no effect on Shroom3 expression or localization but ablates Rock binding and renders Shroom3 non-functional for the ability to regulate cell morphology. Our results indicate that Rock is the major downstream effector of Shroom3 in the process of neural tube morphogenesis. Based on sequence conservation and biochemical analysis, we predict that the Shroom-Rock interaction is highly conserved across animal evolution and represents a signaling module that is utilized in a variety of biological processes.
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Affiliation(s)
- Debamitra Das
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Jenna K Zalewski
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Swarna Mohan
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Timothy F Plageman
- College of Optometry, The Ohio State University, Columbus, OH 43210, USA
| | - Andrew P VanDemark
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Jeffrey D Hildebrand
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
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Reifenberger MS, Yu L, Bao HF, Duke BJ, Liu BC, Ma HP, Alli AA, Eaton DC, Alli AA. Cytochalasin E alters the cytoskeleton and decreases ENaC activity in Xenopus 2F3 cells. Am J Physiol Renal Physiol 2014; 307:F86-95. [PMID: 24829507 DOI: 10.1152/ajprenal.00251.2013] [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: 11/22/2022] Open
Abstract
Numerous reports have linked cytoskeleton-associated proteins with the regulation of epithelial Na(+) channel (ENaC) activity. The purpose of the present study was to determine the effect of actin cytoskeleton disruption by cytochalasin E on ENaC activity in Xenopus 2F3 cells. Here, we show that cytochalasin E treatment for 60 min can disrupt the integrity of the actin cytoskeleton in cultured Xenopus 2F3 cells. We show using single channel patch-clamp experiments and measurements of short-circuit current that ENaC activity, but not its density, is altered by cytochalasin E-induced disruption of the cytoskeleton. In nontreated cells, 8 of 33 patches (24%) had no measurable ENaC activity, whereas in cytochalasin E-treated cells, 17 of 32 patches (53%) had no activity. Analysis of those patches that did contain ENaC activity showed channel open probability significantly decreased from 0.081 ± 0.01 in nontreated cells to 0.043 ± 0.01 in cells treated with cytochalasin E. Transepithelial current from mpkCCD cells treated with cytochalasin E, cytochalasin D, or latrunculin B for 60 min was decreased compared with vehicle-treated cells. The subcellular expression of fodrin changed significantly, and several protein elements of the cytoskeleton decreased at least twofold after 60 min of cytochalasin E treatment. Cytochalasin E treatment disrupted the association between ENaC and myristoylated alanine-rich C-kinase substrate. The results presented here suggest disruption of the actin cytoskeleton by different compounds can attenuate ENaC activity through a mechanism involving changes in the subcellular expression of fodrin, several elements of the cytoskeleton, and destabilization of the ENaC-myristoylated alanine-rich C-kinase substrate complex.
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Affiliation(s)
- Matthew S Reifenberger
- Department of Physiology and the Center for Cell and Molecular Signaling, Emory University School of Medicine, Atlanta, Georgia
| | - Ling Yu
- Department of Physiology and the Center for Cell and Molecular Signaling, Emory University School of Medicine, Atlanta, Georgia
| | - Hui-Fang Bao
- Department of Physiology and the Center for Cell and Molecular Signaling, Emory University School of Medicine, Atlanta, Georgia
| | - Billie Jeanne Duke
- Department of Physiology and the Center for Cell and Molecular Signaling, Emory University School of Medicine, Atlanta, Georgia
| | - Bing-Chen Liu
- Department of Physiology and the Center for Cell and Molecular Signaling, Emory University School of Medicine, Atlanta, Georgia
| | - He-Ping Ma
- Department of Physiology and the Center for Cell and Molecular Signaling, Emory University School of Medicine, Atlanta, Georgia
| | - Ahmed A Alli
- Department of Physiology and the Center for Cell and Molecular Signaling, Emory University School of Medicine, Atlanta, Georgia
| | - Douglas C Eaton
- Department of Physiology and the Center for Cell and Molecular Signaling, Emory University School of Medicine, Atlanta, Georgia
| | - Abdel A Alli
- Department of Physiology and the Center for Cell and Molecular Signaling, Emory University School of Medicine, Atlanta, Georgia
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Hypotonic Regulation of Mouse Epithelial Sodium Channel in Xenopus laevis Oocytes. J Membr Biol 2013; 246:949-58. [DOI: 10.1007/s00232-013-9598-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 09/24/2013] [Indexed: 10/26/2022]
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