1
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Florio M, Engfors A, Gena P, Larsson J, Massaro A, Timpka S, Reimer MK, Kjellbom P, Beitz E, Johanson U, Rützler M, Calamita G. Characterization of the Aquaporin-9 Inhibitor RG100204 In Vitro and in db/db Mice. Cells 2022; 11:3118. [PMID: 36231080 PMCID: PMC9562188 DOI: 10.3390/cells11193118] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 09/22/2022] [Accepted: 09/26/2022] [Indexed: 11/17/2022] Open
Abstract
Aquaporin-9 (AQP9) is a facilitator of glycerol and other small neutral solute transmembrane diffusion. Identification of specific inhibitors for aquaporin family proteins has been difficult, due to high sequence similarity between the 13 human isoforms, and due to the limited channel surface areas that permit inhibitor binding. The few AQP9 inhibitor molecules described to date were not suitable for in vivo experiments. We now describe the characterization of a new small molecule AQP9 inhibitor, RG100204 in cell-based calcein-quenching assays, and by stopped-flow light-scattering recordings of AQP9 permeability in proteoliposomes. Moreover, we investigated the effects of RG100204 on glycerol metabolism in mice. In cell-based assays, RG100204 blocked AQP9 water permeability and glycerol permeability with similar, high potency (~5 × 10-8 M). AQP9 channel blocking by RG100204 was confirmed in proteoliposomes. After oral gavage of db/db mice with RG100204, a dose-dependent elevation of plasma glycerol was observed. A blood glucose-lowering effect was not statistically significant. These experiments establish RG100204 as a direct blocker of the AQP9 channel, and suggest its use as an experimental tool for in vivo experiments on AQP9 function.
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Affiliation(s)
- Marilina Florio
- Department of Biosciences, Biotechnologies and Environment, University of Bari Aldo Moro, 70125 Bari, Italy
| | - Angelica Engfors
- Division of Biochemistry and Structural Biology, Department of Chemistry, Lund University, 22100 Lund, Sweden
| | - Patrizia Gena
- Department of Biosciences, Biotechnologies and Environment, University of Bari Aldo Moro, 70125 Bari, Italy
| | | | - Alessandro Massaro
- Department of Management, Finance and Technology, Libera Università Mediterranea (LUM) “Giuseppe Degennaro” LUM University, 70010 Casamassima, Italy
- LUM Enterprise Srl, S.S. 100-Km18, Parco il Baricentro, 70010 Bari, Italy
| | - Stella Timpka
- Red Glead Discovery AB, Medicon Village, 22381 Lund, Sweden
| | | | - Per Kjellbom
- Division of Biochemistry and Structural Biology, Department of Chemistry, Lund University, 22100 Lund, Sweden
| | - Eric Beitz
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Christian-Albrechts-University of Kiel, Gutenbergstr. 76, 24118 Kiel, Germany
| | - Urban Johanson
- Division of Biochemistry and Structural Biology, Department of Chemistry, Lund University, 22100 Lund, Sweden
| | - Michael Rützler
- Division of Biochemistry and Structural Biology, Department of Chemistry, Lund University, 22100 Lund, Sweden
- Apoglyx AB, Medicon Village, 22381 Lund, Sweden
| | - Giuseppe Calamita
- Department of Biosciences, Biotechnologies and Environment, University of Bari Aldo Moro, 70125 Bari, Italy
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2
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Charlestin V, Fulkerson D, Arias Matus CE, Walker ZT, Carthy K, Littlepage LE. Aquaporins: New players in breast cancer progression and treatment response. Front Oncol 2022; 12:988119. [PMID: 36212456 PMCID: PMC9532844 DOI: 10.3389/fonc.2022.988119] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 08/09/2022] [Indexed: 11/30/2022] Open
Abstract
Aquaporins (AQPs) are a family of small transmembrane proteins that selectively transport water and other small molecules and ions following an osmotic gradient across cell plasma membranes. This enables them to regulate numerous functions including water homeostasis, fat metabolism, proliferation, migration, and adhesion. Previous structural and functional studies highlight a strong biological relationship between AQP protein expression, localization, and key biological functions in normal and cancer tissues, where aberrant AQP expression correlates with tumorigenesis and metastasis. In this review, we discuss the roles of AQP1, AQP3, AQP4, AQP5, and AQP7 in breast cancer progression and metastasis, including the role of AQPs in the tumor microenvironment, to highlight potential contributions of stromal-derived to epithelial-derived AQPs to breast cancer. Emerging evidence identifies AQPs as predictors of response to cancer therapy and as targets for increasing their sensitivity to treatment. However, these studies have not evaluated the requirements for protein structure on AQP function within the context of breast cancer. We also examine how AQPs contribute to a patient's response to cancer treatment, existing AQP inhibitors and how AQPs could serve as novel predictive biomarkers of therapy response in breast cancer. Future studies also should evaluate AQP redundancy and compensation as mechanisms used to overcome aberrant AQP function. This review highlights the need for additional research into how AQPs contribute molecularly to therapeutic resistance and by altering the tumor microenvironment.
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Affiliation(s)
- Verodia Charlestin
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, United States
- Harper Cancer Research Institute, University of Notre Dame, South Bend, IN, United States
| | - Daniel Fulkerson
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, United States
- Harper Cancer Research Institute, University of Notre Dame, South Bend, IN, United States
| | - Carlos E. Arias Matus
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, United States
- Harper Cancer Research Institute, University of Notre Dame, South Bend, IN, United States
- Department of Biotechnology, Universidad Popular Autónoma del Estado de Puebla, Pue, Mexico
| | - Zachary T. Walker
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, United States
- Harper Cancer Research Institute, University of Notre Dame, South Bend, IN, United States
| | - Kevin Carthy
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, United States
- Harper Cancer Research Institute, University of Notre Dame, South Bend, IN, United States
| | - Laurie E. Littlepage
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, United States
- Harper Cancer Research Institute, University of Notre Dame, South Bend, IN, United States
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3
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Galluccio M, Console L, Pochini L, Scalise M, Giangregorio N, Indiveri C. Strategies for Successful Over-Expression of Human Membrane Transport Systems Using Bacterial Hosts: Future Perspectives. Int J Mol Sci 2022; 23:ijms23073823. [PMID: 35409183 PMCID: PMC8998559 DOI: 10.3390/ijms23073823] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 03/28/2022] [Accepted: 03/28/2022] [Indexed: 02/06/2023] Open
Abstract
Ten percent of human genes encode for membrane transport systems, which are key components in maintaining cell homeostasis. They are involved in the transport of nutrients, catabolites, vitamins, and ions, allowing the absorption and distribution of these compounds to the various body regions. In addition, roughly 60% of FDA-approved drugs interact with membrane proteins, among which are transporters, often responsible for pharmacokinetics and side effects. Defects of membrane transport systems can cause diseases; however, knowledge of the structure/function relationships of transporters is still limited. Among the expression of hosts that produce human membrane transport systems, E. coli is one of the most favorable for its low cultivation costs, fast growth, handiness, and extensive knowledge of its genetics and molecular mechanisms. However, the expression in E. coli of human membrane proteins is often toxic due to the hydrophobicity of these proteins and the diversity in structure with respect to their bacterial counterparts. Moreover, differences in codon usage between humans and bacteria hamper translation. This review summarizes the many strategies exploited to achieve the expression of human transport systems in bacteria, providing a guide to help people who want to deal with this topic.
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Affiliation(s)
- Michele Galluccio
- Unit of Biochemistry and Molecular Biotechnology, Department of Biology, Ecology and Earth Sciences (DiBEST), University of Calabria, Via P. Bucci 4c, Arcavacata di Rende, 87036 Cosenza, Italy; (M.G.); (L.C.); (L.P.); (M.S.)
| | - Lara Console
- Unit of Biochemistry and Molecular Biotechnology, Department of Biology, Ecology and Earth Sciences (DiBEST), University of Calabria, Via P. Bucci 4c, Arcavacata di Rende, 87036 Cosenza, Italy; (M.G.); (L.C.); (L.P.); (M.S.)
| | - Lorena Pochini
- Unit of Biochemistry and Molecular Biotechnology, Department of Biology, Ecology and Earth Sciences (DiBEST), University of Calabria, Via P. Bucci 4c, Arcavacata di Rende, 87036 Cosenza, Italy; (M.G.); (L.C.); (L.P.); (M.S.)
| | - Mariafrancesca Scalise
- Unit of Biochemistry and Molecular Biotechnology, Department of Biology, Ecology and Earth Sciences (DiBEST), University of Calabria, Via P. Bucci 4c, Arcavacata di Rende, 87036 Cosenza, Italy; (M.G.); (L.C.); (L.P.); (M.S.)
| | - Nicola Giangregorio
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnology (IBIOM), National Research Council (CNR), Via Amendola 165/A, 70126 Bari, Italy;
| | - Cesare Indiveri
- Unit of Biochemistry and Molecular Biotechnology, Department of Biology, Ecology and Earth Sciences (DiBEST), University of Calabria, Via P. Bucci 4c, Arcavacata di Rende, 87036 Cosenza, Italy; (M.G.); (L.C.); (L.P.); (M.S.)
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnology (IBIOM), National Research Council (CNR), Via Amendola 165/A, 70126 Bari, Italy;
- Correspondence:
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4
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Yue K, Jiang J, Zhang P, Kai L. Functional Analysis of Aquaporin Water Permeability Using an Escherichia coli-Based Cell-Free Protein Synthesis System. Front Bioeng Biotechnol 2020; 8:1000. [PMID: 32974321 PMCID: PMC7466572 DOI: 10.3389/fbioe.2020.01000] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 07/31/2020] [Indexed: 11/13/2022] Open
Abstract
Aquaporins are essential water channel proteins found in all kingdoms of life. Although the water permeability of aquaporins has been well characterized, sample preparation for aquaporin water permeability assays remains challenging and time-consuming. Besides the difficulty in overexpressing membrane proteins in a cell-based expression system, the unique requirement for homogeneity in aquaporin proteoliposome sample preparations for water transport assays further increases the complexity. In this study, a complementary Cell-free Protein Synthesis (CFPS) method is described in detail, providing three different strategies for the preparation of aquaporin proteoliposome samples. Aquaporin can be produced either as a pellet fraction and then resolubilized, or co-translationally as a detergent-soluble fraction. Furthermore, aquaporin can be directly incorporated into liposomes, which was included in the CFPS reactions. Although proteoliposomes tend to fuse during the incubation of the CFPS reactions, an additional treatment of the fused samples with detergent, followed by a detergent removal step, can re-form homogenously sized proteoliposomes suitable for functional analysis. Using this method, we successfully characterized aquaporins from both prokaryotic and eukaryotic organisms. In particular, in the presence of liposomes, the developed CFPS expression system is a fast and convenient method for sample preparation for the functional analysis of aquaporins.
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Affiliation(s)
- Ke Yue
- The Key Laboratory of Biotechnology for Medicinal Plants of Jiangsu Province, School of Life Sciences, Jiangsu Normal University, Xuzhou, China
| | - Jihong Jiang
- The Key Laboratory of Biotechnology for Medicinal Plants of Jiangsu Province, School of Life Sciences, Jiangsu Normal University, Xuzhou, China
| | - Peng Zhang
- The Key Laboratory of Biotechnology for Medicinal Plants of Jiangsu Province, School of Life Sciences, Jiangsu Normal University, Xuzhou, China
| | - Lei Kai
- The Key Laboratory of Biotechnology for Medicinal Plants of Jiangsu Province, School of Life Sciences, Jiangsu Normal University, Xuzhou, China
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5
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Gena P, Portincasa P, Matera S, Sonntag Y, Rützler M, Calamita G. Stopped-flow Light Scattering Analysis of Red Blood Cell Glycerol Permeability. Bio Protoc 2020; 10:e3723. [PMID: 33659385 DOI: 10.21769/bioprotoc.3723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 05/20/2020] [Accepted: 06/29/2020] [Indexed: 11/02/2022] Open
Abstract
Stopped-Flow Light Scattering (SFLS) is a method devised to analyze the kinetics of fast chemical reactions that result in a significant change of the average molecular weight and/or in the shape of the reaction substrates. Several modifications of the original stopped-flow system have been made leading to a significant extension of its technical applications. One of these modifications allows the biophysical characterization of the water and solute permeability of biological and artificial membranes. Here, we describe a protocol of SFLS to measure the glycerol permeability of isolated human red blood cells (RBCs) and evaluate the pharmacokinetics properties (selectivity and potency) of isoform-specific inhibitors of AQP3, AQP7 and AQP9, three mammalian aquaglyceroporins allowing transport of glycerol across membranes. Suspensions of RBCs (1% hematocrit) are exposed to an inwardly directed gradient of 100 mM glycerol in a SFLS apparatus at 20 °C and the resulting changes in scattered light intensity are recorded at a monochromatic wavelength of 530 nm for 120 s. The SFLS apparatus is set up to have a dead time of 1.6-ms and 99% mixing efficiency in less than 1 ms. Data are fitted to a single exponential function and the related time constant (τ, seconds) of the cell-swelling phase of light scattering corresponding to the osmotic movement of water that accompanies the entry of glycerol into erythrocytes is measured. The coefficient of glycerol permeability ( Pgly , cm/s) of RBCs is calculated with the following equation: Pgly = 1/[(S/V)τ] where τ (s) is the fitted exponential time constant and S/V is the surface-to-volume ratio (cm-1) of the analyzed RBC specimen. Pharmacokinetics of the isoform-specific inhibitors of AQP3, AQP7 and AQP9 are assessed by evaluating the extent of RBC Pgly values resulting after the exposure to serial concentrations of the blockers.
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Affiliation(s)
- Patrizia Gena
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari "Aldo Moro", Bari, Italy
| | - Piero Portincasa
- Clinica Medica "A. Murri", Department of Biomedical Sciences and Human Oncology, Medical School, University of Bari "Aldo Moro", Bari, Italy
| | - Sabino Matera
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari "Aldo Moro", Bari, Italy
| | - Yonathan Sonntag
- Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden
| | - Michael Rützler
- Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden.,ApoGlyx AB, Malmö, Sweden
| | - Giuseppe Calamita
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari "Aldo Moro", Bari, Italy
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6
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Yue K, Trung TN, Zhu Y, Kaldenhoff R, Kai L. Co-Translational Insertion of Aquaporins into Liposome for Functional Analysis via an E. coli Based Cell-Free Protein Synthesis System. Cells 2019; 8:E1325. [PMID: 31717877 PMCID: PMC6912355 DOI: 10.3390/cells8111325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 10/24/2019] [Accepted: 10/24/2019] [Indexed: 01/06/2023] Open
Abstract
Aquaporins are important and well-studied water channel membrane proteins. However, being membrane proteins, sample preparation for functional analysis is tedious and time-consuming. In this paper, we report a new approach for the co-translational insertion of two aquaporins from Escherichia coli and Nicotiana tabacum using the CFPS system. This was done in the presence of liposomes with a modified procedure to form homogenous proteo-liposomes suitable for functional analysis of water permeability using stopped-flow spectrophotometry. Two model aquaporins, AqpZ and NtPIP2;1, were successfully incorporated into the liposome in their active forms. Shifted green fluorescent protein was fused to the C-terminal part of AqpZ to monitor its insertion and status in the lipid environment. This new fast approach offers a fast and straightforward method for the functional analysis of aquaporins in both prokaryotic and eukaryotic organisms.
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Affiliation(s)
- Ke Yue
- The Key Laboratory of Biotechnology for Medicinal Plants of Jiangsu Province, School of Life Sciences, Jiangsu Normal University, Xuzhou 22116, China;
| | - Tran Nam Trung
- Department of Biology, Applied Plant Sciences, Technische Universität Darmstadt, Schnittspahn Strasse 10, D-64287 Darmstadt, Germany; (T.N.T.); (R.K.)
| | - Yiyong Zhu
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing 210095, China;
| | - Ralf Kaldenhoff
- Department of Biology, Applied Plant Sciences, Technische Universität Darmstadt, Schnittspahn Strasse 10, D-64287 Darmstadt, Germany; (T.N.T.); (R.K.)
| | - Lei Kai
- The Key Laboratory of Biotechnology for Medicinal Plants of Jiangsu Province, School of Life Sciences, Jiangsu Normal University, Xuzhou 22116, China;
- Department of Biology, Applied Plant Sciences, Technische Universität Darmstadt, Schnittspahn Strasse 10, D-64287 Darmstadt, Germany; (T.N.T.); (R.K.)
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, D-82152 Martinsried, Germany
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7
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Hajek P, Bader A, Helmstetter F, Henke B, Arnold P, Beitz E. Cell-Free and Yeast-Based Production of the Malarial Lactate Transporter, PfFNT, Delivers Comparable Yield and Protein Quality. Front Pharmacol 2019; 10:375. [PMID: 31024323 PMCID: PMC6467934 DOI: 10.3389/fphar.2019.00375] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 03/26/2019] [Indexed: 11/16/2022] Open
Abstract
Cell-free protein production is an attractive alternative to cell-based expression. Rapid results, small-volume reactions, irrelevance of protein toxicity, flexibility, and openness of the system are strong points in favor of the cell-free system. However, the in vitro situation lacks the cellular quality control machinery comprising e.g., the translocon for inserting membrane proteins into lipid bilayers, and chaperon-assisted protein degradation pathways. Here, we compare yield and protein quality of the lactate transporter, PfFNT, from malaria parasites when produced in Pichia pastoris yeast, or in an Escherichia coli S30-extract-based cell-free system. Besides solubilization and correct folding, PfFNT requires oligomerization into homopentamers. We assessed PfFNT folding/oligomerization and function by transmission electron microscopy imaging, transport assays, and binding of small-molecule inhibitors. For the latter, we used chromatography of the PfFNT-inhibitor complex with dual-wavelength detection, and biolayer interferometry. Our data show, that PfFNT possesses an intrinsic capability for assuming the correct fold, oligomerization pattern, and functionality during in vitro translation. This competence depended on the detergent present in the cell-free reaction. The choice of detergent further affected purification and inhibitor binding. In conclusion, in the presence of a suitable detergent, cell-free systems are very well capable of producing high quality membrane proteins.
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Affiliation(s)
- Philipp Hajek
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Christian-Albrechts-University Kiel, Kiel, Germany
| | - Annika Bader
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Christian-Albrechts-University Kiel, Kiel, Germany
| | - Folknand Helmstetter
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Christian-Albrechts-University Kiel, Kiel, Germany
| | - Björn Henke
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Christian-Albrechts-University Kiel, Kiel, Germany
| | - Philipp Arnold
- Anatomical Institute, Christian-Albrechts-University Kiel, Kiel, Germany
| | - Eric Beitz
- Department of Pharmaceutical and Medicinal Chemistry, Pharmaceutical Institute, Christian-Albrechts-University Kiel, Kiel, Germany
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8
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Abir-Awan M, Kitchen P, Salman MM, Conner MT, Conner AC, Bill RM. Inhibitors of Mammalian Aquaporin Water Channels. Int J Mol Sci 2019; 20:ijms20071589. [PMID: 30934923 PMCID: PMC6480248 DOI: 10.3390/ijms20071589] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 03/25/2019] [Accepted: 03/26/2019] [Indexed: 01/29/2023] Open
Abstract
Aquaporins (AQPs) are water channel proteins that are essential to life, being expressed in all kingdoms. In humans, there are 13 AQPs, at least one of which is found in every organ system. The structural biology of the AQP family is well-established and many functions for AQPs have been reported in health and disease. AQP expression is linked to numerous pathologies including tumor metastasis, fluid dysregulation, and traumatic injury. The targeted modulation of AQPs therefore presents an opportunity to develop novel treatments for diverse conditions. Various techniques such as video microscopy, light scattering and fluorescence quenching have been used to test putative AQP inhibitors in both AQP-expressing mammalian cells and heterologous expression systems. The inherent variability within these methods has caused discrepancy and many molecules that are inhibitory in one experimental system (such as tetraethylammonium, acetazolamide, and anti-epileptic drugs) have no activity in others. Some heavy metal ions (that would not be suitable for therapeutic use) and the compound, TGN-020, have been shown to inhibit some AQPs. Clinical trials for neuromyelitis optica treatments using anti-AQP4 IgG are in progress. However, these antibodies have no effect on water transport. More research to standardize high-throughput assays is required to identify AQP modulators for which there is an urgent and unmet clinical need.
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Affiliation(s)
- Mohammed Abir-Awan
- School of Life & Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK.
| | - Philip Kitchen
- School of Life & Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK.
| | - Mootaz M Salman
- Department of Cell Biology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA.
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, 200 Longwood Avenue, Boston, MA 02115, USA.
| | - Matthew T Conner
- Research Institute of Health Sciences, School of Sciences, University of Wolverhampton, Wolverhampton WV1 1LY, UK.
| | - Alex C Conner
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
| | - Roslyn M Bill
- School of Life & Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK.
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9
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Helmstetter F, Arnold P, Höger B, Petersen LM, Beitz E. Formate-nitrite transporters carrying nonprotonatable amide amino acids instead of a central histidine maintain pH-dependent transport. J Biol Chem 2018; 294:623-631. [PMID: 30455351 DOI: 10.1074/jbc.ra118.006340] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 11/09/2018] [Indexed: 01/25/2023] Open
Abstract
Microbial formate-nitrite transporter-type proteins (FNT) exhibit dual transport functionality. At neutral pH, electrogenic anion currents are detectable, whereas upon acidification transport of the neutral, protonated monoacid predominates. Physiologically, FNT-mediated proton co-transport is vital when monocarboxylic acid products of the energy metabolism, such as l-lactate, are released from the cell. Accordingly, Plasmodium falciparum malaria parasites can be killed by small-molecule inhibitors of PfFNT. Two opposing hypotheses on the site of substrate protonation are plausible. The proton relay mechanism postulates proton transfer from a highly conserved histidine centrally positioned in the transport path. The dielectric slide mechanism assumes decreasing acidity of substrates entering the lipophilic vestibules and protonation via the bulk water. Here, we defined the transport mechanism of the FNT from the amoebiasis parasite Entamoeba histolytica, EhFNT, and also show that BtFdhC from Bacillus thuringiensis is a functional formate transporter. Both FNTs carry a nonprotonatable amide amino acid, asparagine or glutamine, respectively, at the central histidine position. Despite having a nonprotonatable residue, EhFNT displayed the same substrate selectivity for larger monocarboxylates including l-lactate, a low substrate affinity as is typical for FNTs, and, strikingly, proton motive force-dependent transport as observed for PfFNT harboring a central histidine. These results argue against a proton relay mechanism, indicating that substrate protonation must occur outside of the central histidine region, most likely in the vestibules. Furthermore, EhFNT is the sole annotated FNT in the Entamoeba genome suggesting that it could be a putative new drug target with similar utility as that of the malarial PfFNT.
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Affiliation(s)
| | - Philipp Arnold
- the Anatomical Institute, Christian-Albrechts-University of Kiel, 24118 Kiel, Germany
| | - Bastian Höger
- From the Department of Pharmaceutical and Medicinal Chemistry, and
| | | | - Eric Beitz
- From the Department of Pharmaceutical and Medicinal Chemistry, and
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10
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Lipopolysaccharide Modifies Glycerol Permeability and Metabolism in 3T3-L1 Adipocytes. Int J Mol Sci 2017; 18:ijms18122566. [PMID: 29186031 PMCID: PMC5751169 DOI: 10.3390/ijms18122566] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 11/09/2017] [Accepted: 11/25/2017] [Indexed: 12/15/2022] Open
Abstract
Aquaglyceroporins-aquaporin membrane channels (AQP) that conduct glycerol and other small neutral solutes in addition to water-play major roles in obesity. In adipocytes, aquaglyceroporins mediate glycerol uptake and release across the plasma membrane, which are two key steps for triacylglycerols (TAGs) synthesis (lipogenesis) and hydrolysis (lipolysis). The aim of this study was to assess both glycerol permeability and metabolism in undifferentiated 3T3-L1 cells (UDCs) as well as in untreated (CTL-DCs) versus lipopolysaccharide (LPS-DCs)-treated differentiated 3T3-L1 adipocytes. Glycerol release, TAGs content and whole membrane glycerol permeability were significantly increased in DCs as compared to UDCs. Moreover, in DCs, LPS treatment significantly increased TAGs content and decreased glycerol permeability. In addition, a significant reduction in whole membrane glycerol permeability was observed in LPS-DCs as compared to CTL-DCs. The relative contributions of AQP3, AQP7 and AQP9 (facilitated diffusion), as well as that of the phospholipid bilayer (simple diffusion), to the whole membrane glycerol permeability, were estimated biophysically in UDCs, CTL-DCs and LPS-DCs, using selective AQP inhibitors. Further studies will be required to determine if modifications in either subcellular localization and/or activity of aquaglyceroporins could account for the data herein. Nevertheless, our findings provide novel insights in understanding the LPS-induced adipocyte hypertrophy that accompanies obesity.
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11
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Palmgren M, Hernebring M, Eriksson S, Elbing K, Geijer C, Lasič S, Dahl P, Hansen JS, Topgaard D, Lindkvist-Petersson K. Quantification of the Intracellular Life Time of Water Molecules to Measure Transport Rates of Human Aquaglyceroporins. J Membr Biol 2017; 250:629-639. [PMID: 28914342 PMCID: PMC5696491 DOI: 10.1007/s00232-017-9988-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 09/07/2017] [Indexed: 01/13/2023]
Abstract
Orthodox aquaporins are transmembrane channel proteins that facilitate rapid diffusion of water, while aquaglyceroporins facilitate the diffusion of small uncharged molecules such as glycerol and arsenic trioxide. Aquaglyceroporins play important roles in human physiology, in particular for glycerol metabolism and arsenic detoxification. We have developed a unique system applying the strain of the yeast Pichia pastoris, where the endogenous aquaporins/aquaglyceroporins have been removed and human aquaglyceroporins AQP3, AQP7, and AQP9 are recombinantly expressed enabling comparative permeability measurements between the expressed proteins. Using a newly established Nuclear Magnetic Resonance approach based on measurement of the intracellular life time of water, we propose that human aquaglyceroporins are poor facilitators of water and that the water transport efficiency is similar to that of passive diffusion across native cell membranes. This is distinctly different from glycerol and arsenic trioxide, where high glycerol transport efficiency was recorded.
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Affiliation(s)
- Madelene Palmgren
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, 405 30, Göteborg, Sweden
| | - Malin Hernebring
- Department of Experimental Medical Science, Lund University, BMC C13, 221 84, Lund, Sweden
| | - Stefanie Eriksson
- Physical Chemistry, Lund University, P.O.B. 124, 22100, Lund, Sweden
| | - Karin Elbing
- Department of Experimental Medical Science, Lund University, BMC C13, 221 84, Lund, Sweden
| | - Cecilia Geijer
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, 405 30, Göteborg, Sweden
| | - Samo Lasič
- CR Development, AB, Naturvetarvägen 14, 22362, Lund, Sweden
| | - Peter Dahl
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, 405 30, Göteborg, Sweden
| | - Jesper S Hansen
- Department of Experimental Medical Science, Lund University, BMC C13, 221 84, Lund, Sweden
| | - Daniel Topgaard
- Physical Chemistry, Lund University, P.O.B. 124, 22100, Lund, Sweden
| | - Karin Lindkvist-Petersson
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, 405 30, Göteborg, Sweden. .,Department of Experimental Medical Science, Lund University, BMC C13, 221 84, Lund, Sweden.
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Wei P, Wang Q, Hang B, Shi F, Cai J, Huang L, Xu Z. High-level cell-free expression and functional characterization of a novel aquaporin from Photobactetrium profundum SS9. Process Biochem 2017. [DOI: 10.1016/j.procbio.2017.05.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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13
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Abstract
The large-scale production of recombinant G protein-coupled receptors (GPCRs) is one of the major bottlenecks that hamper functional and structural studies of this important class of integral membrane proteins. Heterologous overexpression of GPCRs often results in low yields of active protein, usually due to a combination of several factors, such as low expression levels, protein insolubility, host cell toxicity, and the need to use harsh and often denaturing detergents (e.g., SDS, LDAO, OG, and DDM, among others) to extract the recombinant receptor from the host cell membrane. Many of these problematic issues are inherently linked to cell-based expression systems and can therefore be circumvented by the use of cell-free systems. In this unit, we provide a range of protocols for the production of GPCRs in a cell-free expression system. Using this system, we typically obtain GPCR expression levels of ∼1 mg per ml of reaction mixture in the continuous-exchange configuration. Although the protocols in this unit have been optimized for the cell-free expression of GPCRs, they should provide a good starting point for the production of other classes of membrane proteins, such as ion channels, aquaporins, carrier proteins, membrane-bound enzymes, and even large molecular complexes.
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Affiliation(s)
- Kenneth Segers
- VIB Center for the Biology of Disease, Flanders Institute for Biotechnology (VIB), Leuven, Belgium.,Structural Biology Group, Biologics Research Europe, Janssen Research & Development, Beerse, Belgium
| | - Stefan Masure
- Structural Biology Group, Biologics Research Europe, Janssen Research & Development, Beerse, Belgium
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Scalera V, Gena P, Mastrodonato M, Kitagawa Y, Carulli S, Svelto M, Calamita G. Functional reconstitution of a rice aquaporin water channel, PIP1;1, by a micro-batchwise methodology. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2014; 85:78-84. [PMID: 25394803 DOI: 10.1016/j.plaphy.2014.10.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Accepted: 10/29/2014] [Indexed: 05/08/2023]
Abstract
Assessing the selectivity, regulation and physiological relevance of aquaporin membrane channels (AQPs)requires structural and functional studies of wild type and modified proteins. In particular, when characterizing their transport properties, reconstitution in isolation from native cellular or membrane processes is of pivotal importance. Here, we describe rapid and efficient incorporation of OsPIP1;1, a rice AQP, in liposomes at analytical scale. PIP1;1 was produced as a histidine-tagged form, 10 His-OsPIP1;1, in an Escherichia coli-based expression system. The recombinant protein was purified by affinity chromatography and incorporated into liposomes by a micro-batchwise technology using egg-yolk phospholipids and the non-polar Amberlite resin. PIP1;1 proteoliposomes and control empty liposomes had good size homogeneity as seen by quasi-elastic light scattering and electron microscopy analyses. By stopped-flow light scattering, indicating correct protein folding of the incorporated protein, the osmotic water permeability exhibited by the PIP1;1 proteoliposomes was markedly higher than empty liposomes. Functional reconstitution of OsPIP1;1 was further confirmed by the low Arrhenius activation energy (3.37 kcal/mol) and sensitivity to HgCl2, a known AQP blocker, of the PIP1;1-mediated osmotic water conductance. These results provide a valuable contribution in fully elucidating the regulation and water-conducting property of PIP1;1, an AQP that needs to hetero-multimerize with AQPs of the PIP2 subgroupto reach the native plasma membrane and play its role. The micro-batchwise methodology is suitable for the functional reconstitution of whichever AQPs and other membrane transport proteins.
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