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Xu L, Guo X, Wang W, Li C. Classification and Gene Structure of Aquaporins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1398:1-13. [PMID: 36717483 DOI: 10.1007/978-981-19-7415-1_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Aquaporins (AQPs) are a family of membrane water channels that basically function as regulators of intracellular and intercellular water flow. To date, 13 AQPs, distributed widely in specific cell types in various organs and tissues, have been characterized in humans. A pair of NPA boxes forming a pore is highly conserved among all aquaporins and is also key residues for the classification of AQP superfamily into four groups according to primary sequences. AQPs may also be classified based on their transport properties. So far, chromosome localization and gene structure of 13 human AQPs have been identified, which is definitely helpful for studying phenotypes and potential targets in naturally occurring and synthetic mutations in human or cells.
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Affiliation(s)
- Long Xu
- Department of Physiology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Xiangdong Guo
- Department of Physiology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Weidong Wang
- Department of Pathophysiology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China.
| | - Chunling Li
- Department of Physiology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China.
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2
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Insight into the Mammalian Aquaporin Interactome. Int J Mol Sci 2022; 23:ijms23179615. [PMID: 36077012 PMCID: PMC9456110 DOI: 10.3390/ijms23179615] [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] [Received: 07/25/2022] [Revised: 08/16/2022] [Accepted: 08/22/2022] [Indexed: 01/07/2023] Open
Abstract
Aquaporins (AQPs) are a family of transmembrane water channels expressed in all living organisms. AQPs facilitate osmotically driven water flux across biological membranes and, in some cases, the movement of small molecules (such as glycerol, urea, CO2, NH3, H2O2). Protein-protein interactions play essential roles in protein regulation and function. This review provides a comprehensive overview of the current knowledge of the AQP interactomes and addresses the molecular basis and functional significance of these protein-protein interactions in health and diseases. Targeting AQP interactomes may offer new therapeutic avenues as targeting individual AQPs remains challenging despite intense efforts.
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3
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Markou A, Unger L, Abir-Awan M, Saadallah A, Halsey A, Balklava Z, Conner M, Törnroth-Horsefield S, Greenhill SD, Conner A, Bill RM, Salman MM, Kitchen P. Molecular mechanisms governing aquaporin relocalisation. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183853. [PMID: 34973181 PMCID: PMC8825993 DOI: 10.1016/j.bbamem.2021.183853] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 12/20/2021] [Accepted: 12/21/2021] [Indexed: 02/07/2023]
Abstract
The aquaporins (AQPs) form a family of integral membrane proteins that facilitate the movement of water across biological membrane by osmosis, as well as facilitating the diffusion of small polar solutes. AQPs have been recognised as drug targets for a variety of disorders associated with disrupted water or solute transport, including brain oedema following stroke or trauma, epilepsy, cancer cell migration and tumour angiogenesis, metabolic disorders, and inflammation. Despite this, drug discovery for AQPs has made little progress due to a lack of reproducible high-throughput assays and difficulties with the druggability of AQP proteins. However, recent studies have suggested that targetting the trafficking of AQP proteins to the plasma membrane is a viable alternative drug target to direct inhibition of the water-conducting pore. Here we review the literature on the trafficking of mammalian AQPs with a view to highlighting potential new drug targets for a variety of conditions associated with disrupted water and solute homeostasis.
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Affiliation(s)
- Andrea Markou
- College of Health and Life Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Lucas Unger
- College of Health and Life Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Mohammed Abir-Awan
- College of Health and Life Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Ahmed Saadallah
- College of Health and Life Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Andrea Halsey
- MRC Institute of Metabolic Science, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Zita Balklava
- College of Health and Life Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Matthew Conner
- School of Sciences, Research Institute in Healthcare Science, University of Wolverhampton, Wolverhampton WV1 1LY, UK
| | | | - Stuart D Greenhill
- College of Health and Life Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Alex Conner
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Roslyn M Bill
- College of Health and Life Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Mootaz M Salman
- Department of Physiology Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK; Oxford Parkinson's Disease Centre, University of Oxford, South Parks Road, Oxford OX1 3QX, UK.
| | - Philip Kitchen
- College of Health and Life Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK.
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4
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Current Methods to Unravel the Functional Properties of Lysosomal Ion Channels and Transporters. Cells 2022; 11:cells11060921. [PMID: 35326372 PMCID: PMC8946281 DOI: 10.3390/cells11060921] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 03/04/2022] [Accepted: 03/05/2022] [Indexed: 02/07/2023] Open
Abstract
A distinct set of channels and transporters regulates the ion fluxes across the lysosomal membrane. Malfunctioning of these transport proteins and the resulting ionic imbalance is involved in various human diseases, such as lysosomal storage disorders, cancer, as well as metabolic and neurodegenerative diseases. As a consequence, these proteins have stimulated strong interest for their suitability as possible drug targets. A detailed functional characterization of many lysosomal channels and transporters is lacking, mainly due to technical difficulties in applying the standard patch-clamp technique to these small intracellular compartments. In this review, we focus on current methods used to unravel the functional properties of lysosomal ion channels and transporters, stressing their advantages and disadvantages and evaluating their fields of applicability.
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5
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Wagner K, Unger L, Salman MM, Kitchen P, Bill RM, Yool AJ. Signaling Mechanisms and Pharmacological Modulators Governing Diverse Aquaporin Functions in Human Health and Disease. Int J Mol Sci 2022; 23:1388. [PMID: 35163313 PMCID: PMC8836214 DOI: 10.3390/ijms23031388] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 01/18/2022] [Accepted: 01/20/2022] [Indexed: 02/07/2023] Open
Abstract
The aquaporins (AQPs) are a family of small integral membrane proteins that facilitate the bidirectional transport of water across biological membranes in response to osmotic pressure gradients as well as enable the transmembrane diffusion of small neutral solutes (such as urea, glycerol, and hydrogen peroxide) and ions. AQPs are expressed throughout the human body. Here, we review their key roles in fluid homeostasis, glandular secretions, signal transduction and sensation, barrier function, immunity and inflammation, cell migration, and angiogenesis. Evidence from a wide variety of studies now supports a view of the functions of AQPs being much more complex than simply mediating the passive flow of water across biological membranes. The discovery and development of small-molecule AQP inhibitors for research use and therapeutic development will lead to new insights into the basic biology of and novel treatments for the wide range of AQP-associated disorders.
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Affiliation(s)
- Kim Wagner
- School of Biomedicine, University of Adelaide, Adelaide, SA 5005, Australia;
| | - Lucas Unger
- College of Health and Life Sciences, Aston University, Birmingham B4 7ET, UK; (L.U.); (P.K.)
| | - Mootaz M. Salman
- Department of Physiology Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK;
- Oxford Parkinson’s Disease Centre, University of Oxford, South Parks Road, Oxford OX1 3QX, UK
| | - Philip Kitchen
- College of Health and Life Sciences, Aston University, Birmingham B4 7ET, UK; (L.U.); (P.K.)
| | - Roslyn M. Bill
- College of Health and Life Sciences, Aston University, Birmingham B4 7ET, UK; (L.U.); (P.K.)
| | - Andrea J. Yool
- School of Biomedicine, University of Adelaide, Adelaide, SA 5005, Australia;
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6
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Henderson SW, Nourmohammadi S, Ramesh SA, Yool AJ. Aquaporin ion conductance properties defined by membrane environment, protein structure, and cell physiology. Biophys Rev 2022; 14:181-198. [PMID: 35340612 PMCID: PMC8921385 DOI: 10.1007/s12551-021-00925-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 12/09/2021] [Indexed: 01/13/2023] Open
Abstract
Aquaporins (AQPs) are multifunctional transmembrane channel proteins permeable to water and an expanding array of solutes. AQP-mediated ion channel activity was first observed when purified AQP0 from bovine lens was incorporated into lipid bilayers. Electrophysiological properties of ion-conducting AQPs since discovered in plants, invertebrates, and mammals have been assessed using native, reconstituted, and heterologously expressed channels. Accumulating evidence is defining amino acid residues that govern differential solute permeability through intrasubunit and central pores of AQP tetramers. Rings of charged and hydrophobic residues around pores influence AQP selectivity, and are candidates for further work to define motifs that distinguish ion conduction capability, versus strict water and glycerol permeability. Similarities between AQP ion channels thus far include large single channel conductances and long open times, but differences in ionic selectivity, permeability to divalent cations, and mechanisms of gating (e.g., by voltage, pH, and cyclic nucleotides) are unique to subtypes. Effects of lipid environments in modulating parameters such as single channel amplitude could explain in part the variations in AQP ion channel properties observed across preparations. Physiological roles of the ion-conducting AQP classes span diverse processes including regulation of cell motility, organellar pH, neural development, signaling, and nutrient acquisition. Advances in computational methods can generate testable predictions of AQP structure-function relationships, which combined with innovative high-throughput assays could revolutionize the field in defining essential properties of ion-conducting AQPs, discovering new AQP ion channels, and understanding the effects of AQP interactions with proteins, signaling cascades, and membrane lipids.
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Affiliation(s)
- Sam W. Henderson
- School of Biomedicine, University of Adelaide, Adelaide, SA 5005 Australia
| | | | - Sunita A. Ramesh
- College of Science and Engineering, Flinders University, Bedford Park, SA 5042 Australia
| | - Andrea J. Yool
- School of Biomedicine, University of Adelaide, Adelaide, SA 5005 Australia
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7
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Soler DC, Kowatz T, Sloan AE, McCormick TS, Cooper KD, Stepanyan R, Engel A, Vahedi-Faridi A. A region within the third extracellular loop of rat Aquaporin 6 precludes trafficking to plasma membrane in a heterologous cell line. Sci Rep 2021; 11:13673. [PMID: 34211055 PMCID: PMC8249660 DOI: 10.1038/s41598-021-93117-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 05/31/2021] [Indexed: 11/09/2022] Open
Abstract
The inability to over-express Aquaporin 6 (AQP6) in the plasma membrane of heterologous cells has hampered efforts to further characterize the function of this aquaglyceroporin membrane protein at atomic detail using crystallographic approaches. Using an Aquaporin 3-tGFP Reporter (AGR) system we have identified a region within loop C of AQP6 that is responsible for severely hampering plasma membrane expression. Serine substitution corroborated that amino acids present within AQP6194–213 of AQP6 loop C contribute to intracellular endoplasmic reticulum (ER) retention. This intracellular retention signal may preclude proper plasma membrane trafficking and severely curtail expression of AQP6 in heterologous expression systems.
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Affiliation(s)
- D C Soler
- The Department of Neurosurgery, Case Western Reserve University, Cleveland, USA.
| | - T Kowatz
- Department of Physiology and Biophysics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106-4965, USA
| | - A E Sloan
- The Department of Neurosurgery, Case Western Reserve University, Cleveland, USA.,Brain Tumor and Neuro-Oncology Center, University Hospitals Cleveland Medical Center, Cleveland, USA
| | - T S McCormick
- Department of Dermatology, Case Western Reserve University, Cleveland, USA.,Murdough Family Center for Psoriasis, Case Western Reserve University, Cleveland, USA
| | - K D Cooper
- Department of Dermatology, Case Western Reserve University, Cleveland, USA.,Murdough Family Center for Psoriasis, Case Western Reserve University, Cleveland, USA
| | - R Stepanyan
- Department of Otolaryngology-HNS, Case Western Reserve University, Cleveland, USA.,Department of Neurosciences, Case Western Reserve University, Cleveland, USA
| | - A Engel
- Biozentrum, University of Basel, Basel, Switzerland
| | - A Vahedi-Faridi
- Department of Physiology and Biophysics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106-4965, USA
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8
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Tyerman SD, McGaughey SA, Qiu J, Yool AJ, Byrt CS. Adaptable and Multifunctional Ion-Conducting Aquaporins. ANNUAL REVIEW OF PLANT BIOLOGY 2021; 72:703-736. [PMID: 33577345 DOI: 10.1146/annurev-arplant-081720-013608] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Aquaporins function as water and neutral solute channels, signaling hubs, disease virulence factors, and metabolon components. We consider plant aquaporins that transport ions compared to some animal counterparts. These are candidates for important, as yet unidentified, cation and anion channels in plasma, tonoplast, and symbiotic membranes. For those individual isoforms that transport ions, water, and gases, the permeability spans 12 orders of magnitude. This requires tight regulation of selectivity via protein interactions and posttranslational modifications. A phosphorylation-dependent switch between ion and water permeation in AtPIP2;1 might be explained by coupling between the gates of the four monomer water channels and the central pore of the tetramer. We consider the potential for coupling between ion and water fluxes that could form the basis of an electroosmotic transducer. A grand challenge in understanding the roles of ion transporting aquaporins is their multifunctional modes that are dependent on location, stress, time, and development.
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Affiliation(s)
- Stephen D Tyerman
- Australian Research Council (ARC) Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, South Australia 5064, Australia; ,
| | - Samantha A McGaughey
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, Australian Capital Territory 0200, Australia; ,
| | - Jiaen Qiu
- Australian Research Council (ARC) Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, South Australia 5064, Australia; ,
| | - Andrea J Yool
- Adelaide Medical School, University of Adelaide, Adelaide, South Australia 5005, Australia;
| | - Caitlin S Byrt
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, Australian Capital Territory 0200, Australia; ,
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9
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Pellavio G, Laforenza U. Human sperm functioning is related to the aquaporin-mediated water and hydrogen peroxide transport regulation. Biochimie 2021; 188:45-51. [PMID: 34087390 DOI: 10.1016/j.biochi.2021.05.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 05/11/2021] [Accepted: 05/23/2021] [Indexed: 10/21/2022]
Abstract
Aquaporins (AQPs) are transmembrane water channels and some of them are permeable in addition to water to other small solutes including hydrogen peroxide. The sperm cells of mammals and fishes express different AQPs, although there is no agreement in the literature on their localization. In humans, AQP3 and AQP11 are expressed mainly in the tail, AQP7 in the head and AQP8 in the midpiece. Thanks to the results of experiments with KO mice and to data obtained by comparing sub-fertile patients with normospermic subjects, the importance of AQPs for the normal functioning of sperms to ensure normal fertility emerged. AQP3, AQP7 and AQP11 appeared involved in the sperm volume regulation, a key role for fertility because osmoadaptation protect the sperm against a swelling and tail bending that could affect sperm motility. AQP8 seems to have a fundamental role in regulating the elimination of hydrogen peroxide, the most abundant reactive oxygen species (ROS), and therefore in the response to oxidative stress. In this review, the human AQPs expression, their localization and functions, as well as their relevance in normal fertility are discussed. To understand better the AQPs role in human sperm functionality, the results of studies obtained in other animal species were also considered.
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Affiliation(s)
- Giorgia Pellavio
- Department of Molecular Medicine, Human Physiology Unit, University of Pavia, Pavia, I-27100, Italy
| | - Umberto Laforenza
- Department of Molecular Medicine, Human Physiology Unit, University of Pavia, Pavia, I-27100, Italy.
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10
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Comparative Analysis of the aquaporin Gene Family in 12 Fish Species. Animals (Basel) 2019; 9:ani9050233. [PMID: 31086002 PMCID: PMC6562760 DOI: 10.3390/ani9050233] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 05/10/2019] [Accepted: 05/11/2019] [Indexed: 01/15/2023] Open
Abstract
Simple Summary Aquaporins (Aqps) are a group of membrane proteins. In this study, 166 Aqp genes were identified in 12 fish species. Gene organization, motif distribution, recombination, and selection pressure were performed to investigate their evolutionary characteristics. In addition, expression profiles of Aqps were also examined under pathogens infection and organophosphorus pesticide stress. This study will provide a useful reference for further functional study. Abstract Aquaporins (Aqps) are a class of water channel proteins that play key roles in many physiological functions and cellular processes. Here, we analyzed 166 putative Aqp genes in 12 fish species and divided them into four groups. Gene organization and motif distribution analyses suggested potentially conserved functions in each group. Several recombination events were identified in some members, which accelerate their divergence in evolution. Furthermore, a few positive selection sites were identified, and mutations at these sites could alter the stability of Aqp proteins. In addition, expression profiles of some Aqp genes under pathogen infection and organophosphorus pesticide stress were also investigated. The result implied that several Aqp genes may affect different immune responses and osmoregulation. This study provides a comparative analysis of the fish Aqp gene family to facilitate further functional analyses.
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11
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The Expanding Role of Vesicles Containing Aquaporins. Cells 2018; 7:cells7100179. [PMID: 30360436 PMCID: PMC6210599 DOI: 10.3390/cells7100179] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 10/16/2018] [Accepted: 10/20/2018] [Indexed: 12/11/2022] Open
Abstract
In animals and plants, membrane vesicles containing proteins have been defined as key for biological systems involving different processes such as trafficking or intercellular communication. Docking and fusion of vesicles to the plasma membrane occur in living cells in response to different stimuli, such as environmental changes or hormones, and therefore play an important role in cell homeostasis as vehicles for certain proteins or other substances. Because aquaporins enhance the water permeability of membranes, their role as proteins immersed in vesicles formed of natural membranes is a recent topic of study. They regulate numerous physiological processes and could hence serve new biotechnological purposes. Thus, in this review, we have explored the physiological implications of the trafficking of aquaporins, the mechanisms that control their transit, and the proteins that coregulate the migration. In addition, the importance of exosomes containing aquaporins in the cell-to-cell communication processes in animals and plants have been analyzed, together with their potential uses in biomedicine or biotechnology. The properties of aquaporins make them suitable for use as biomarkers of different aquaporin-related diseases when they are included in exosomes. Finally, the fact that these proteins could be immersed in biomimetic membranes opens future perspectives for new biotechnological applications.
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12
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Thapa S, Chetry M, Huang K, Peng Y, Wang J, Wang J, Zhou Y, Shen Y, Xue Y, Ji K. Significance of aquaporins' expression in the prognosis of gastric cancer. Biosci Rep 2018; 38:BSR20171687. [PMID: 29678898 PMCID: PMC5997799 DOI: 10.1042/bsr20171687] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Revised: 03/30/2018] [Accepted: 04/20/2018] [Indexed: 01/20/2023] Open
Abstract
Gastric carcinoma is one of the most lethal malignancy at present with leading cause of cancer-related deaths worldwide. Aquaporins (AQPs) are a family of small, integral membrane proteins, which have been evidenced to play a crucial role in cell migration and proliferation of different cancer cells including gastric cancers. However, the aberrant expression of specific AQPs and its correlation to detect predictive and prognostic significance in gastric cancer remains elusive. In the present study, we comprehensively explored immunohistochemistry based map of protein expression profiles in normal tissues, cancer and cell lines from publicly available Human Protein Atlas (HPA) database. Moreover, to improve our understanding of general gastric biology and guide to find novel predictive prognostic gastric cancer biomarker, we also retrieved 'The Kaplan-Meier plotter' (KM plotter) online database with specific AQPs mRNA to overall survival (OS) in different clinicopathological features. We revealed that ubiquitous expression of AQPs protein can be effective tools to generate gastric cancer biomarker. Furthermore, high level AQP3, AQP9, and AQP11 mRNA expression were correlated with better OS in all gastric patients, whereas AQP0, AQP1, AQP4, AQP5, AQP6, AQP8, and AQP10 mRNA expression were associated with poor OS. With regard to the clinicopathological features including Laurens classification, clinical stage, human epidermal growth factor receptor 2 (HER2) status, and different treatment strategy, we could illustrate significant role of individual AQP mRNA expression in the prognosis of gastric cancer patients. Thus, our results indicated that AQP's protein and mRNA expression in gastric cancer patients provide effective role to predict prognosis and act as an essential agent to therapeutic strategy.
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Affiliation(s)
- Saroj Thapa
- Department of Cardiology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325000, China
| | - Mandika Chetry
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325000, China
| | - Kaiyu Huang
- Department of Cardiology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325000, China
| | - Yangpei Peng
- Department of Cardiology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325000, China
| | - Jinsheng Wang
- Department of Cardiology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325000, China
| | - Jiaoni Wang
- Department of Cardiology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325000, China
| | - Yingying Zhou
- Department of Cardiology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325000, China
| | - Yigen Shen
- Department of Cardiology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325000, China
| | - Yangjing Xue
- Department of Cardiology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325000, China
| | - Kangting Ji
- Department of Cardiology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325000, China
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13
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Laloux T, Junqueira B, Maistriaux LC, Ahmed J, Jurkiewicz A, Chaumont F. Plant and Mammal Aquaporins: Same but Different. Int J Mol Sci 2018; 19:E521. [PMID: 29419811 PMCID: PMC5855743 DOI: 10.3390/ijms19020521] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 01/31/2018] [Accepted: 02/01/2018] [Indexed: 02/06/2023] Open
Abstract
Aquaporins (AQPs) constitute an ancient and diverse protein family present in all living organisms, indicating a common ancient ancestor. However, during evolution, these organisms appear and evolve differently, leading to different cell organizations and physiological processes. Amongst the eukaryotes, an important distinction between plants and animals is evident, the most conspicuous difference being that plants are sessile organisms facing ever-changing environmental conditions. In addition, plants are mostly autotrophic, being able to synthesize carbohydrates molecules from the carbon dioxide in the air during the process of photosynthesis, using sunlight as an energy source. It is therefore interesting to analyze how, in these different contexts specific to both kingdoms of life, AQP function and regulation evolved. This review aims at highlighting similarities and differences between plant and mammal AQPs. Emphasis is given to the comparison of isoform numbers, their substrate selectivity, the regulation of the subcellular localization, and the channel activity.
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Affiliation(s)
- Timothée Laloux
- Institut des Sciences de la Vie, Université catholique de Louvain, Croix du Sud 4-L7.07.14, B-1348 Louvain-la Neuve, Belgium.
| | - Bruna Junqueira
- Institut des Sciences de la Vie, Université catholique de Louvain, Croix du Sud 4-L7.07.14, B-1348 Louvain-la Neuve, Belgium.
| | - Laurie C Maistriaux
- Institut des Sciences de la Vie, Université catholique de Louvain, Croix du Sud 4-L7.07.14, B-1348 Louvain-la Neuve, Belgium.
| | - Jahed Ahmed
- Institut des Sciences de la Vie, Université catholique de Louvain, Croix du Sud 4-L7.07.14, B-1348 Louvain-la Neuve, Belgium.
| | - Agnieszka Jurkiewicz
- Institut des Sciences de la Vie, Université catholique de Louvain, Croix du Sud 4-L7.07.14, B-1348 Louvain-la Neuve, Belgium.
| | - François Chaumont
- Institut des Sciences de la Vie, Université catholique de Louvain, Croix du Sud 4-L7.07.14, B-1348 Louvain-la Neuve, Belgium.
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14
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Molinas A, Turkina MV, Magnusson KE, Mirazimi A, Vikström E. Perturbation of Wound Healing, Cytoskeletal Organization and Cellular Protein Networks during Hazara Virus Infection. Front Cell Dev Biol 2017; 5:98. [PMID: 29209610 PMCID: PMC5702460 DOI: 10.3389/fcell.2017.00098] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 11/06/2017] [Indexed: 12/11/2022] Open
Abstract
Normal epithelial and endothelial renewal and healing after bacterial and viral challenges are essential for homeostasis along the intestine and the blood and lymphatic vessels. We thus investigated whether and how virus affects migration of human epithelial cells and specifically how the nucleocapsid protein (N) modulates the cellular proteome and interactome using human Caco-2 cells in a wound-healing assay with Hazara virus as a model. Here, Hazara virus blocked cell migration in a dose- and time-dependent manner, disrupted the actin cytoskeleton and specifically reduced the expression of the IQ-motif-containing GTPase-activating protein 1 (IQGAP1) and water channel aquaporin 6 (AQP6) that regulate cytoskeletal organization, water homeostasis and vesicle communication. Moreover, in the Caco-2 cell proteome, we identified several distinct groups of molecules associating with N upon Hazara virus infection, being involved in the ensemble of important cellular processes, e.g., chaperone activity, metabolism, cellular defense against infections, cell morphology, and migration. These events do not only facilitate the virus life cycle, but they are also crucial for membrane and cytoskeleton dynamics, cellular self-renewal and wound healing, being so essential for body integrity and homeostasis.
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Affiliation(s)
- Andrea Molinas
- Department of Clinical and Experimental Medicine, Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden
| | - Maria V Turkina
- Department of Clinical and Experimental Medicine, Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden
| | - Karl-Eric Magnusson
- Department of Clinical and Experimental Medicine, Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden
| | - Ali Mirazimi
- Department of Laboratory Medicine, Karolinska Institute, Stockholm, Sweden
| | - Elena Vikström
- Department of Clinical and Experimental Medicine, Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden
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15
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Abstract
Aquaporins (AQPs ) are a family of membrane water channels that basically function as regulators of intracellular and intercellular water flow. To date, thirteen AQPs , which are distributed widely in specific cell types in various organs and tissues, have been characterized in humans. Four AQP monomers, each of which consists of six membrane-spanning alpha-helices that have a central water-transporting pore, assemble to form tetramers, forming the functional units in the membrane. AQP facilitates osmotic water transport across plasma membranes and thus transcellular fluid movement. The cellular functions of aquaporins are regulated by posttranslational modifications , e.g. phosphorylation, ubiquitination, glycosylation, subcellular distribution, degradation, and protein interactions. Insight into the molecular mechanisms responsible for regulated aquaporin trafficking and synthesis is proving to be fundamental for development of novel therapeutic targets or reliable diagnostic and prognostic biomarkers.
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Affiliation(s)
- Chunling Li
- Institute of Hypertension, Zhongshan School of Medicine, Sun Yat-sen University, 74# Zhongshan Er Road, Guangzhou, 510080, China
| | - Weidong Wang
- Institute of Hypertension, Zhongshan School of Medicine, Sun Yat-sen University, 74# Zhongshan Er Road, Guangzhou, 510080, China.
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16
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Molinas A, Mirazimi A, Holm A, Loitto VM, Magnusson KE, Vikström E. Protective role of host aquaporin 6 against Hazara virus, a model for Crimean-Congo hemorrhagic fever virus infection. FEMS Microbiol Lett 2016; 363:fnw058. [PMID: 26976854 DOI: 10.1093/femsle/fnw058] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/06/2016] [Indexed: 12/26/2022] Open
Abstract
Crimean-Congo hemorrhagic fever virus (CCHFV) is an arthropod-borne pathogen that causes infectious disease with severe hemorrhagic manifestations in vascular system in humans. The proper function of the cells in the vascular system is critically regulated by aquaporins (AQP), water channels that facilitate fluxes of water and small solutes across membranes. With Hazara virus as a model for CCHFV, we investigated the effects of viruses on AQP6 and the impact of AQP6 on virus infectivity in host cells, using transiently expressed GFP-AQP6 cells, immunofluorescent assay for virus detection, epifluorescent imaging of living cells and confocal microscopy. In GFP-AQP6 expressing cells, Hazara virus reduced both the cellular and perinuclear AQP6 distribution and changed the cell area. Infection of human cell with CCHFV strain IbAR 10200 downregulated AQP6 expression at mRNA level. Interestingly, the overexpression of AQP6 in host cells decreased the infectivity of Hazara virus, speaking for a protective role of AQP6. We suggest the possibility for AQP6 being a novel player in the virus-host interactions, which may lead to less severe outcomes of an infection.
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Affiliation(s)
- Andrea Molinas
- Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, SE-581 85 Linköping, Sweden
| | - Ali Mirazimi
- Department of Laboratory Medicine, Karolinska Institute, SE-171 77 Stockholm, Sweden
| | - Angelika Holm
- Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, SE-581 85 Linköping, Sweden
| | - Vesa M Loitto
- Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, SE-581 85 Linköping, Sweden
| | - Karl-Eric Magnusson
- Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, SE-581 85 Linköping, Sweden
| | - Elena Vikström
- Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, SE-581 85 Linköping, Sweden
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17
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Stavang JA, Chauvigné F, Kongshaug H, Cerdà J, Nilsen F, Finn RN. Phylogenomic and functional analyses of salmon lice aquaporins uncover the molecular diversity of the superfamily in Arthropoda. BMC Genomics 2015; 16:618. [PMID: 26282991 PMCID: PMC4539701 DOI: 10.1186/s12864-015-1814-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 08/03/2015] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND An emerging field in biomedical research is focusing on the roles of aquaporin water channels in parasites that cause debilitating or lethal diseases to their vertebrate hosts. The primary vectorial agents are hematophagous arthropods, including mosquitoes, flies, ticks and lice, however very little is known concerning the functional diversity of aquaporins in non-insect members of the Arthropoda. Here we conducted phylogenomic and functional analyses of aquaporins in the salmon louse, a marine ectoparasitic copepod that feeds on the skin and body fluids of salmonids, and used the primary structures of the isolated channels to uncover the genomic repertoires in Arthropoda. RESULTS Genomic screening identified 7 aquaporin paralogs in the louse in contrast to 42 in its host the Atlantic salmon. Phylogenetic inference of the louse nucleotides and proteins in relation to orthologs identified in Chelicerata, Myriapoda, Crustacea and Hexapoda revealed that the arthropod aquaporin superfamily can be classified into three major grades (1) classical aquaporins including Big brain (Bib) and Prip-like (PripL) channels (2) aquaglyceroporins (Glp) and (3) unorthodox aquaporins (Aqp12-like). In Hexapoda, two additional subfamilies exist as Drip and a recently classified entomoglyceroporin (Eglp) group. Cloning and remapping the louse cDNAs to the genomic DNA revealed that they are encoded by 1-7 exons, with two of the Glps being expressed as N-terminal splice variants (Glp1_v1, -1_v2, -3_v1, -3_v2). Heterologous expression of the cRNAs in amphibian oocytes demonstrated that PripL transports water and urea, while Bib does not. Glp1_v1, -2, -3_v1 and -3_v2 each transport water, glycerol and urea, while Glp1_v2 and the Aqp12-like channels were retained intracellularly. Transcript abundance analyses revealed expression of each louse paralog at all developmental stages, except for glp1_v1, which is specific to preadult and adult males. CONCLUSIONS Our data suggest that the aquaporin repertoires of extant arthropods have expanded independently in the different lineages, but can be phylogenetically classified into three major grades as opposed to four present in deuterostome animals. While the aquaporin repertoire of Atlantic salmon represents a 6-fold redundancy compared to the louse, the functional assays reveal that the permeation properties of the different crustacean grades of aquaporin are largely conserved to the vertebrate counterparts.
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Affiliation(s)
- Jon Anders Stavang
- Sea Lice Research Centre, Department of Biology, Bergen High Technology Centre, University of Bergen, 5020, Bergen, Norway.
| | - Francois Chauvigné
- Sea Lice Research Centre, Department of Biology, Bergen High Technology Centre, University of Bergen, 5020, Bergen, Norway.
- Institut de Recerca i Tecnologia Agroalimentàries (IRTA)-Institut de Ciències del Mar, Consejo Superior de Investigaciones Científicas (CSIC), 08003, Barcelona, Spain.
| | - Heidi Kongshaug
- Sea Lice Research Centre, Department of Biology, Bergen High Technology Centre, University of Bergen, 5020, Bergen, Norway.
| | - Joan Cerdà
- Institut de Recerca i Tecnologia Agroalimentàries (IRTA)-Institut de Ciències del Mar, Consejo Superior de Investigaciones Científicas (CSIC), 08003, Barcelona, Spain.
| | - Frank Nilsen
- Sea Lice Research Centre, Department of Biology, Bergen High Technology Centre, University of Bergen, 5020, Bergen, Norway.
| | - Roderick Nigel Finn
- Sea Lice Research Centre, Department of Biology, Bergen High Technology Centre, University of Bergen, 5020, Bergen, Norway.
- Institute of Marine Research, Nordnes, 5817, Bergen, Norway.
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18
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Abstract
In this review, we provide a brief synopsis of the evolution and functional diversity of the aquaporin gene superfamily in prokaryotic and eukaryotic organisms. Based upon the latest data, we discuss the expanding list of molecules shown to permeate the central pore of aquaporins, and the unexpected diversity of water channel genes in Archaea and Bacteria. We further provide new insight into the origin by horizontal gene transfer of plant glycerol-transporting aquaporins (NIPs), and the functional co-option and gene replacement of insect glycerol transporters. Finally, we discuss the origins of four major grades of aquaporins in Eukaryota, together with the increasing repertoires of aquaporins in vertebrates.
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Affiliation(s)
- Roderick Nigel Finn
- Department of Biology, Bergen High Technology Centre, University of Bergen, Norway; Institute of Marine Research, Nordnes, 5817 Bergen, Norway; and
| | - Joan Cerdà
- Institut de Recerca i Tecnologia Agroalimentàries (IRTA)-Institut de Ciències del Mar, Consejo Superior de Investigaciones Científicas (CSIC), 08003 Barcelona, Spain
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19
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The lineage-specific evolution of aquaporin gene clusters facilitated tetrapod terrestrial adaptation. PLoS One 2014; 9:e113686. [PMID: 25426855 PMCID: PMC4245216 DOI: 10.1371/journal.pone.0113686] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 10/27/2014] [Indexed: 01/02/2023] Open
Abstract
A major physiological barrier for aquatic organisms adapting to terrestrial life is dessication in the aerial environment. This barrier was nevertheless overcome by the Devonian ancestors of extant Tetrapoda, but the origin of specific molecular mechanisms that solved this water problem remains largely unknown. Here we show that an ancient aquaporin gene cluster evolved specifically in the sarcopterygian lineage, and subsequently diverged into paralogous forms of AQP2, -5, or -6 to mediate water conservation in extant Tetrapoda. To determine the origin of these apomorphic genomic traits, we combined aquaporin sequencing from jawless and jawed vertebrates with broad taxon assembly of >2,000 transcripts amongst 131 deuterostome genomes and developed a model based upon Bayesian inference that traces their convergent roots to stem subfamilies in basal Metazoa and Prokaryota. This approach uncovered an unexpected diversity of aquaporins in every lineage investigated, and revealed that the vertebrate superfamily consists of 17 classes of aquaporins (Aqp0 - Aqp16). The oldest orthologs associated with water conservation in modern Tetrapoda are traced to a cluster of three aqp2-like genes in Actinistia that likely arose >500 Ma through duplication of an aqp0-like gene present in a jawless ancestor. In sea lamprey, we show that aqp0 first arose in a protocluster comprised of a novel aqp14 paralog and a fused aqp01 gene. To corroborate these findings, we conducted phylogenetic analyses of five syntenic nuclear receptor subfamilies, which, together with observations of extensive genome rearrangements, support the coincident loss of ancestral aqp2-like orthologs in Actinopterygii. We thus conclude that the divergence of sarcopterygian-specific aquaporin gene clusters was permissive for the evolution of water conservation mechanisms that facilitated tetrapod terrestrial adaptation.
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20
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Rambow J, Wu B, Rönfeldt D, Beitz E. Aquaporins with anion/monocarboxylate permeability: mechanisms, relevance for pathogen-host interactions. Front Pharmacol 2014; 5:199. [PMID: 25225485 PMCID: PMC4150397 DOI: 10.3389/fphar.2014.00199] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 08/12/2014] [Indexed: 11/22/2022] Open
Abstract
Classically, aquaporins are divided based on pore selectivity into water specific, orthodox aquaporins and solute-facilitating aquaglyceroporins, which conduct, e.g., glycerol and urea. However, more aquaporin-passing substrates have been identified over the years, such as the gasses ammonia and carbon dioxide or the water-related hydrogen peroxide. It became apparent that not all aquaporins clearly fit into one of only two subfamilies. Furthermore, certain aquaporins from both major subfamilies have been reported to conduct inorganic anions, such as chloride, or monoacids/monocarboxylates, such as lactic acid/lactate. Here, we summarize the findings on aquaporin anion transport, analyze the pore layout of such aquaporins in comparison to prototypical non-selective anion channels, monocarboxylate transporters, and formate–nitrite transporters. Finally, we discuss in which scenarios anion conducting aquaporins may be of physiological relevance.
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Affiliation(s)
- Janis Rambow
- Department of Pharmaceutical and Medicinal Chemistry, Christian-Albrechts-University of Kiel Kiel, Germany
| | - Binghua Wu
- Department of Pharmaceutical and Medicinal Chemistry, Christian-Albrechts-University of Kiel Kiel, Germany
| | - Deike Rönfeldt
- Department of Pharmaceutical and Medicinal Chemistry, Christian-Albrechts-University of Kiel Kiel, Germany
| | - Eric Beitz
- Department of Pharmaceutical and Medicinal Chemistry, Christian-Albrechts-University of Kiel Kiel, Germany
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21
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Takahashi S, Muta K, Sonoda H, Kato A, Abdeen A, Ikeda M. The role of Cysteine 227 in subcellular localization, water permeability, and multimerization of aquaporin-11. FEBS Open Bio 2014; 4:315-20. [PMID: 24918044 PMCID: PMC4048847 DOI: 10.1016/j.fob.2014.03.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 03/12/2014] [Accepted: 03/12/2014] [Indexed: 12/31/2022] Open
Abstract
Aquaporin-11 (AQP11) is the latest member of the mammalian water channel protein family to be described. Recent in vivo studies have shown that mutation at Cys(227) causes renal failure. However the importance of Cys(227) for the molecular function of AQP11 is largely unknown. In this study, we examined the subcellular localization, water permeability, and multimerization of AQP11 with a mutation at Cys(227). Interestingly, cells expressing the mutants had significantly higher osmotic water permeability. In contrast, the mutation lowered the cell surface expression and multimerization levels. Our observations suggest that Cys(227) is crucial for the proper molecular function of AQP11.
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Affiliation(s)
- Saki Takahashi
- Department of Veterinary Pharmacology, University of Miyazaki, Miyazaki 889-2192, Japan
| | - Kanako Muta
- Department of Veterinary Pharmacology, University of Miyazaki, Miyazaki 889-2192, Japan
| | - Hiroko Sonoda
- Department of Veterinary Pharmacology, University of Miyazaki, Miyazaki 889-2192, Japan
| | - Ayaka Kato
- Department of Veterinary Pharmacology, University of Miyazaki, Miyazaki 889-2192, Japan
| | - Ahmed Abdeen
- Department of Veterinary Pharmacology, University of Miyazaki, Miyazaki 889-2192, Japan
| | - Masahiro Ikeda
- Department of Veterinary Pharmacology, University of Miyazaki, Miyazaki 889-2192, Japan
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22
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Almasalmeh A, Krenc D, Wu B, Beitz E. Structural determinants of the hydrogen peroxide permeability of aquaporins. FEBS J 2013; 281:647-56. [PMID: 24286224 DOI: 10.1111/febs.12653] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 11/24/2013] [Accepted: 11/25/2013] [Indexed: 12/27/2022]
Abstract
Aquaporins (AQP) conduct small, uncharged molecules, such as water (orthodox AQPs), ammonia (aquaammoniaporins) or glycerol (aquaglyceroporins). The physiological functions of AQPs are involved in osmotic volume regulation or the transport of biochemical precursors and metabolic waste products. The recent identification of hydrogen peroxide (H₂O₂) as a permeant of certain AQPs suggests additional roles in mitigating oxidative stress or enabling paracrine H₂O₂ signalling. Yet, an analysis of the structural requirements of the H₂O₂ permeability of AQPs is missing. We subjected a representative set of wild-type and mutant AQPs to a newly established quantitative phenotypic assay. We confirmed high H₂O₂ permeability of the human aquaammoniaporin AQP8 and found intermediate H₂O₂ permeability of the prototypical orthodox water channel AQP1 from the rat. Differences from an earlier report showing an absence of H₂O₂ permeability of human AQP1 can be explained by expression levels. By generating point mutations in the selectivity filter of rat orthodox aquaporin AQP1, we established a correlation of H₂O₂ permeability primarily with water permeability and secondarily with the pore diameter. Even the narrowest pore of the test set (i.e. rat orthodox aquaporin AQP1 H180F with a pore diameter smaller than that of natural orthodox AQPs) conducted water and H₂O₂. We further found that H₂O₂ permeability of the aquaglyceroporin from the malaria parasite Plasmodium falciparum was lower despite its wider pore diameter. The data suggest that all water-permeable AQPs are H₂O₂ channels, yet H₂O₂ permeability varies with the isoform. Thus, generally, AQPs must be considered as putative players in situations of oxidative stress (e.g. in Plasmodium-infected red blood cells, immune cells, the cardiovascular system or cells expressing AQP8 in their mitochondria).
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Affiliation(s)
- Abdulnasser Almasalmeh
- Department of Pharmaceutical and Medicinal Chemistry, Christian-Albrechts-University of Kiel, Germany
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23
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Ip YK, Soh MML, Chen XL, Ong JLY, Chng YR, Ching B, Wong WP, Lam SH, Chew SF. Molecular characterization of branchial aquaporin 1aa and effects of seawater acclimation, emersion or ammonia exposure on its mRNA expression in the gills, gut, kidney and skin of the freshwater climbing perch, Anabas testudineus. PLoS One 2013; 8:e61163. [PMID: 23593418 PMCID: PMC3621907 DOI: 10.1371/journal.pone.0061163] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2012] [Accepted: 03/06/2013] [Indexed: 12/27/2022] Open
Abstract
We obtained a full cDNA coding sequence of aquaporin 1aa (aqp1aa) from the gills of the freshwater climbing perch, Anabas testudineus, which had the highest expression in the gills and skin, suggesting an important role of Aqp1aa in these organs. Since seawater acclimation had no significant effects on the branchial and intestinal aqp1aa mRNA expression, and since the mRNA expression of aqp1aa in the gut was extremely low, it can be deduced that Aqp1aa, despite being a water channel, did not play a significant osmoregulatory role in A. testudineus. However, terrestrial exposure led to significant increases in the mRNA expression of aqp1aa in the gills and skin of A. testudineus. Since terrestrial exposure would lead to evaporative water loss, these results further support the proposition that Aqp1aa did not function predominantly for the permeation of water through the gills and skin. Rather, increased aqp1aa mRNA expression might be necessary to facilitate increased ammonia excretion during emersion, because A. testudineus is known to utilize amino acids as energy sources for locomotor activity with increased ammonia production on land. Furthermore, ammonia exposure resulted in significant decreases in mRNA expression of aqp1aa in the gills and skin of A. testudineus, presumably to reduce ammonia influx during ammonia loading. This corroborates previous reports on AQP1 being able to facilitate ammonia permeation. However, a molecular characterization of Aqp1aa from A. testudineus revealed that its intrinsic aquapore might not facilitate NH3 transport. Hence, ammonia probably permeated the central fifth pore of the Aqp1aa tetramer as suggested previously. Taken together, our results indicate that Aqp1aa might have a greater physiological role in ammonia excretion than in osmoregulation in A. testudineus.
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Affiliation(s)
- Yuen K Ip
- Department of Biological Science, National University of Singapore, Kent Ridge, Singapore, Republic of Singapore.
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24
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Conner AC, Bill RM, Conner MT. An emerging consensus on aquaporin translocation as a regulatory mechanism. Mol Membr Biol 2012; 30:1-12. [DOI: 10.3109/09687688.2012.743194] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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25
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Tamma G, Procino G, Svelto M, Valenti G. Cell culture models and animal models for studying the patho-physiological role of renal aquaporins. Cell Mol Life Sci 2012; 69:1931-46. [PMID: 22189994 PMCID: PMC11114724 DOI: 10.1007/s00018-011-0903-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 11/07/2011] [Accepted: 11/29/2011] [Indexed: 12/29/2022]
Abstract
Aquaporins (AQPs) are key players regulating urinary-concentrating ability. To date, eight aquaporins have been characterized and localized along the nephron, namely, AQP1 located in the proximal tubule, thin descending limb of Henle, and vasa recta; AQP2, AQP3 and AQP4 in collecting duct principal cells; AQP5 in intercalated cell type B; AQP6 in intercalated cells type A in the papilla; AQP7, AQP8 and AQP11 in the proximal tubule. AQP2, whose expression and cellular distribution is dependent on vasopressin stimulation, is involved in hereditary and acquired diseases affecting urine-concentrating mechanisms. Due to the lack of selective aquaporin inhibitors, the patho-physiological role of renal aquaporins has not yet been completely clarified, and despite extensive studies, several questions remain unanswered. Until the recent and large-scale development of genetic manipulation technology, which has led to the generation of transgenic mice models, our knowledge on renal aquaporin regulation was mainly based on in vitro studies with suitable renal cell models. Transgenic and knockout technology approaches are providing pivotal information on the role of aquaporins in health and disease. The main goal of this review is to update and summarize what we can learn from cell and animal models that will shed more light on our understanding of aquaporin-dependent renal water regulation.
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Affiliation(s)
- G Tamma
- Department of Biosciences, Biotechnologies and Pharmacological Sciences, University of Bari, Italy
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26
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Esteva-Font C, Ballarin J, Fernández-Llama P. Molecular biology of water and salt regulation in the kidney. Cell Mol Life Sci 2012; 69:683-95. [PMID: 21997386 PMCID: PMC11114984 DOI: 10.1007/s00018-011-0858-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Revised: 08/18/2011] [Accepted: 09/12/2011] [Indexed: 01/03/2023]
Abstract
The kidney plays a central role in the regulation of the salt and water balance, which depends upon an array of solute and water transporters in the renal tubules and upon vascular elements in the various regions of the kidney. Many recent studies have improved our understanding of this process. In this review, we summarize the current data on the molecules involved in sodium and water transport in the renal tubules, focusing in particular on aquaporins and renal sodium transporters and channels.
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Affiliation(s)
- C. Esteva-Font
- Renal Unit and Hypertension, Fundació Puigvert, Universitat Autònoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Instituto de Investigación Biomédica Sant Pau, Cartagena 340-350, 08025 Barcelona, Spain
| | - J. Ballarin
- Renal Unit and Hypertension, Fundació Puigvert, Universitat Autònoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Instituto de Investigación Biomédica Sant Pau, Cartagena 340-350, 08025 Barcelona, Spain
| | - P. Fernández-Llama
- Renal Unit and Hypertension, Fundació Puigvert, Universitat Autònoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Instituto de Investigación Biomédica Sant Pau, Cartagena 340-350, 08025 Barcelona, Spain
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27
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Abstract
Aquaporins represent a primordial group of transmembrane solvent channels that have been documented throughout the living biota. This facet alone emphasizes the positive selection pressure for proteins associated with intracellular fluid homeostasis. Amongst extant Eukaryota the highest gene copy number can be found in plants and teleosts, a feature that reflects the genomic duplication history in both groups. In this minireview we discuss the discovery, structure, duplication, and diversification of the aquaporin superfamily. We focus on teleosts as the main models, but include data available for other organisms to provide a broader perspective.
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Affiliation(s)
- Roderick Nigel Finn
- Institute of Biology, Bergen High Technology Center, University of Bergen Bergen, Norway
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28
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Braiterman L, Nyasae L, Leves F, Hubbard AL. Critical roles for the COOH terminus of the Cu-ATPase ATP7B in protein stability, trans-Golgi network retention, copper sensing, and retrograde trafficking. Am J Physiol Gastrointest Liver Physiol 2011; 301:G69-81. [PMID: 21454443 PMCID: PMC3129927 DOI: 10.1152/ajpgi.00038.2011] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
ATP7A and ATP7B are copper-transporting P-type ATPases that are essential to eukaryotic copper homeostasis and must traffic between intracellular compartments to carry out their functions. Previously, we identified a nine-amino acid sequence (F37-E45) in the NH(2) terminus of ATP7B that is required to retain the protein in the Golgi when copper levels are low and target it apically in polarized hepatic cells when copper levels rise. To understand further the mechanisms regulating the intracellular dynamics of ATP7B, using multiple functional assays, we characterized the protein phenotypes of 10 engineered and Wilson disease-associated mutations in the ATP7B COOH terminus in polarized hepatic cells and fibroblasts. We also examined the behavior of a chimera between ATP7B and ATP7A. Our results clearly demonstrate the importance of the COOH terminus of ATP7B in the protein's copper-responsive apical trafficking. L1373 at the end of transmembrane domain 8 is required for protein stability and Golgi retention in low copper, the trileucine motif (L1454-L1456) is required for retrograde trafficking, and the COOH terminus of ATP7B exhibits a higher sensitivity to copper than does ATP7A. Importantly, our results demonstrating that four Wilson disease-associated missense mutations behaved in a wild-type manner in all our assays, together with current information in the literature, raise the possibility that several may not be disease-causing mutations.
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Affiliation(s)
- L. Braiterman
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - L. Nyasae
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - F. Leves
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - A. L. Hubbard
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland
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Edemir B, Pavenstädt H, Schlatter E, Weide T. Mechanisms of cell polarity and aquaporin sorting in the nephron. Pflugers Arch 2011; 461:607-21. [PMID: 21327781 DOI: 10.1007/s00424-011-0928-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 01/14/2011] [Accepted: 01/16/2011] [Indexed: 01/02/2023]
Abstract
The kidneys participate in whole-body homeostasis, regulating acid-base balance, electrolyte concentrations, extracellular fluid volume, and regulation of blood pressure. Many of the kidney's functions are accomplished by relatively simple mechanisms of filtration, reabsorption, and secretion, which take place in the nephron. The kidneys generate 140-180 l of primary urine per day, while reabsorbing a large percentage, allowing for only the excretion of approximately 2 l of urine. Within the nephron, the majority of the filtered water and solutes are reabsorbed. This is mainly facilitated by specialized transporters and channels which are localized at different segments of the nephron and asymmetrically localized within the polarized epithelial cells. The asymmetric localization of these transporters and channels is essential for the physiological tasks of the renal tissues. One family of these proteins are the water-permeable aquaporins which are selectively expressed in cells along the nephron and localized at different compartments. Here, we discuss potential molecular links between mechanisms involved in the establishment of cell polarity and the members of the aquaporin family. In the first part of this review, we will focus on aspects of apical cell polarity. In the second part, we will review the motifs identified so far that are involved in aquaporin sorting and point out potential molecular links.
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Affiliation(s)
- Bayram Edemir
- Medizinische Klinik und Poliklinik D, Experimentelle und Molekulare Nephrologie, Universität Münster, Germany.
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Neagoe I, Stauber T, Fidzinski P, Bergsdorf EY, Jentsch TJ. The late endosomal ClC-6 mediates proton/chloride countertransport in heterologous plasma membrane expression. J Biol Chem 2010; 285:21689-97. [PMID: 20466723 DOI: 10.1074/jbc.m110.125971] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Members of the CLC protein family of Cl(-) channels and transporters display the remarkable ability to function as either chloride channels or Cl(-)/H(+) antiporters. Due to the intracellular localization of ClC-6 and ClC-7, it has not yet been possible to study the biophysical properties of these members of the late endosomal/lysosomal CLC branch in heterologous expression. Whereas recent data suggest that ClC-7 functions as an antiporter, transport characteristics of ClC-6 have remained entirely unknown. Here, we report that fusing the green fluorescent protein (GFP) to the N terminus of ClC-6 increased its cell surface expression, allowing us to functionally characterize ClC-6. Compatible with ClC-6 mediating Cl(-)/H(+) exchange, Xenopus oocytes expressing GFP-tagged ClC-6 alkalinized upon depolarization. This alkalinization was dependent on the presence of extracellular anions and could occur against an electrochemical proton gradient. As observed in other CLC exchangers, ClC-6-mediated H(+) transport was abolished by mutations in either the "gating" or "proton" glutamate. Overexpression of GFP-tagged ClC-6 in CHO cells elicited small, outwardly rectifying currents with a Cl(-) > I(-) conductance sequence. Mutating the gating glutamate of ClC-6 yielded an ohmic anion conductance that was increased by additionally mutating the "anion-coordinating" tyrosine. Additionally changing the chloride-coordinating serine 157 to proline increased the NO(3)(-) conductance of this mutant. Taken together, these data demonstrate for the first time that ClC-6 is a Cl(-)/H(+) antiporter.
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Affiliation(s)
- Ioana Neagoe
- Leibniz-Institut für Molekulare Pharmakologie FMP and Max-Delbrück-Centrum für Molekulare Medizin, D-13125 Berlin, Germany
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Aquaporin-6 expression in the cochlear sensory epithelium is downregulated by salicylates. J Biomed Biotechnol 2010; 2010:264704. [PMID: 20111742 PMCID: PMC2810475 DOI: 10.1155/2010/264704] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Revised: 09/21/2009] [Accepted: 10/22/2009] [Indexed: 11/17/2022] Open
Abstract
We characterize the expression pattern of aquaporin-6 in the mouse inner ear by RT-PCR and immunohistochemistry. Our data show that in the inner ear aquaporin-6 is expressed, in both vestibular and acoustic sensory epithelia, by the supporting cells directly contacting hair cells. In particular, in the Organ of Corti, expression was strongest in Deiters' cells, which provide both a mechanical link between outer hair cells (OHCs) and the Organ of Corti, and an entry point for ion recycle pathways. Since aquaporin-6 is permeable to both water and anions, these results suggest its possible involvement in regulating OHC motility, directly through modulation of water and chloride flow or by changing mechanical compliance in Deiters' cells. In further support of this role, treating mice with salicylates, which impair OHC electromotility, dramatically reduced aquaporin-6 expression in the inner ear epithelia but not in control tissues, suggesting a role for this protein in modulating OHCs' responses.
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Shih PY, Lin CL, Cheng PW, Liao JH, Pan CY. Calneuron I inhibits Ca(2+) channel activity in bovine chromaffin cells. Biochem Biophys Res Commun 2009; 388:549-53. [PMID: 19682431 DOI: 10.1016/j.bbrc.2009.08.046] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2009] [Accepted: 08/07/2009] [Indexed: 10/20/2022]
Abstract
Calneuron I (CalnI) is a calmodulin-like protein that contains two functional EF-hand motifs at the N-terminal and a hydrophobic segment at the C-terminal. CalnI was cloned from the adult rat cortex and fused with GFP at its N-terminal. When expressed in bovine chromaffin cells, wild-type CalnI was localized at the plasma membrane. However, a mutant that lacked the hydrophobic segment was localized in the cytosol and nucleus, while a Ca(2+)-binding-deficient mutant was found in the cytosol and at the plasma membrane. Evaluation using the whole-cell patch-clamp technique revealed that Ca(2+) currents were inhibited by both wild-type CalnI and the Ca(2+)-binding-deficient mutant. When the bovine N-type Ca(2+) channel was expressed in 293T cells, Ca(2+) currents were mostly inhibited by co-expression of CalnI, but not by the mutant without the hydrophobic tail. These results suggest that CalnI attenuates Ca(2+) channel activity and that its subcellular localization is important for this effect.
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Affiliation(s)
- Po-Yuan Shih
- Institute of Zoology, National Taiwan University, Taipei, Taiwan, ROC
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Aquaporins are multifunctional water and solute transporters highly divergent in living organisms. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:1213-28. [DOI: 10.1016/j.bbamem.2009.03.009] [Citation(s) in RCA: 310] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Revised: 03/09/2009] [Accepted: 03/11/2009] [Indexed: 01/09/2023]
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Rabaud NE, Song L, Wang Y, Agre P, Yasui M, Carbrey JM. Aquaporin 6 binds calmodulin in a calcium-dependent manner. Biochem Biophys Res Commun 2009; 383:54-7. [PMID: 19336226 DOI: 10.1016/j.bbrc.2009.03.128] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Accepted: 03/24/2009] [Indexed: 11/19/2022]
Abstract
Aquaporin 6 (AQP6) is an anion channel that is expressed primarily in acid secreting alpha-intercalated cells of the kidney collecting duct. In addition, AQP6 anion channel permeability is gated by low pH. Inspection of the N-terminus of AQP6 revealed a putative calmodulin binding site. AQP6-expressing CHO-K1 cell lysates were mixed with calmodulin beads and AQP6 was pulled down in the presence of calcium. Mutagenesis of the N-terminal calmodulin binding site in full length mouse AQP6 resulted in a loss of calmodulin binding activity. Mouse and human AQP6 calmodulin binding site peptides bound dansyl-calmodulin with a dissociation constant of approximately 1microM. The binding of AQP6 to calmodulin may be an important key to determining the physiological role of AQP6 in the kidney.
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Affiliation(s)
- Nicole E Rabaud
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
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Abstract
The human aquaporins,AQP3,AQP7, AQP8,AQP9, and possibly AQP10, are permeable to ammonia, and AQP7, AQP9, and possibly AQP3, are permeable to urea. In humans, these aquaporins supplement the ammonia transport of the Rhesus (Rh) proteins and the urea transporters (UTs). The mechanism by which ammonium is transported by aquaporins is not fully resolved. A comparison of transport equations, models, and experimental data shows that ammonia is transported in its neutral form, NH(3). In the presence of NH(3), the aquaporin stimulates H(+) transport. Consequently, this transport of H(+) is only significant at alkaline pH. It is debated whether the H(+) ion passes via the aquaporin or by some external route; the investigation of this problem requires the aquaporin-expressing cell to be voltage-clamped. The ammonia-permeable aquaporins differ from other aquaporins by having a less restrictive aromatic/arginine region, and an exclusively water-permeable aquaporin can be transformed into an ammonia-permeable aquaporin by single point mutations in this region. The ammonia-permeable aquaporins fall into two groups: those that are permeable (AQP3, 7, 9, 10) and those that are impermeable (AQP8) to glycerol. The two groups differ in the amino acid composition of their aromatic/arginine regions. The location of the ammonia-permeable aquaporins in the body parallels that of the Rh proteins. This applies to erythrocytes and to cells associated with nitrogen homeostasis and high rates of anabolism. In the liver, AQPs 8 and 9 are found together with Rh proteins in cells exposed to portal blood coming from the intestine. In the kidney, AQP3 might participate in the excretion of NH(4) (+) in the collecting duct. The interplay between the ammonia-permeable aquaporins and the other types of ammonia- and urea-permeable proteins is not well understood.
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Affiliation(s)
- Thomas Litman
- Exiqon A/S, Department of Biomarker Discovery, Bygstubben 16, Vedbaek, 2950, Denmark
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Zelazny E, Miecielica U, Borst JW, Hemminga MA, Chaumont F. An N-terminal diacidic motif is required for the trafficking of maize aquaporins ZmPIP2;4 and ZmPIP2;5 to the plasma membrane. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2009; 57:346-55. [PMID: 18808456 DOI: 10.1111/j.1365-313x.2008.03691.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Maize plasma membrane aquaporins (ZmPIPs, where PIP is the plasma membrane intrinsic protein) fall into two groups, ZmPIP1s and ZmPIP2s, which, when expressed alone in mesophyll protoplasts, are found in different subcellular locations. Whereas ZmPIP1s are retained in the endoplasmic reticulum (ER), ZmPIP2s are found in the plasma membrane (PM). We previously showed that, when co-expressed with ZmPIP2s, ZmPIP1s are relocalized to the PM, and that this relocalization results from the formation of hetero-oligomers between ZmPIP1s and ZmPIP2s. To determine the domains responsible for the ER retention and PM localization, respectively, of ZmPIP1s and ZmPIP2s, truncated and mutated ZmPIPs were generated, together with chimeric proteins created by swapping the N- or C-terminal regions of ZmPIP2s and ZmPIP1s. These mutated proteins were fused to the mYFP and/or mCFP, and the fusion proteins were expressed in maize mesophyll protoplasts, and were then localized by microscopy. This allowed us to identify a diacidic motif, DIE (Asp-Ile-Glu), at position 4-6 of the N-terminus of ZmPIP2;5, that is essential for ER export. This motif was conserved and functional in ZmPIP2;4, but was absent in ZmPIP2;1. In addition, we showed that the N-terminus of ZmPIP2;5 was not sufficient to cause the export of ZmPIP1;2 from the ER. A study of ZmPIP1;2 mutants suggested that the N- and C-termini of this protein are probably not involved in ER retention. Together, these results show that the trafficking of maize PM aquaporins is differentially regulated depending on the isoform, and involves a specific signal and mechanism.
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Affiliation(s)
- Enric Zelazny
- Institut des Sciences de la Vie, Université catholique de Louvain, Croix du Sud 5-15, B-1348 Louvain-la-Neuve, Belgium
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Abstract
The enzymatic activity of Paracoccus denitrificans cytochrome c oxidase (COX) and Escherichia coli cytochrome b(o) ubiquinol oxidase (QOX) was determined in the presence of formamide, N,N-dimethyl formamide and N,N-dimethyl acetamide. Formamide was found to inhibit the enzyme activity of the oxidases most significantly, whereas the other two compounds inhibited the activity to a lesser extent. The effects of formamide and analogs on enzyme activity were very similar for COX and QOX, indicating that the mechanism of inhibition might be the same for both of these oxidases. The inhibition kinetics followed a non-competitive mechanism. Studies using proteoliposomes of COX and QOX containing the electron entry site of the enzyme directed towards the outside of the vesicles showed that the effect of inhibition by formamide was higher when the inhibitor was present on the outside of the proteoliposome compared to when it was present only in the aqueous core. This indicates that inhibition of enzyme activity by formamide possibly predominantly involves blocking of the water exit pathway in the oxidases.
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Affiliation(s)
- Sayan Gupta
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India
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Abstract
Interactions are the essence of all biomolecules because they cannot fulfill their roles without interacting with other molecules. Hence, mapping the interactions of biomolecules can be useful for understanding their roles and functions. Furthermore, the development of molecular based systems biology requires an understanding of the biomolecular interactions. In recent years, the mapping of protein-protein interactions in different species has been reported, but few reports have focused on the large-scale mapping of protein-protein interactions in human. Here, we review the developments in protein interaction mapping and we discuss issues and strategies for the mapping of the human protein interactome.
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Abstract
Membrane transport proteins are integral membrane proteins and considered as potential drug targets. Activity assay of transport proteins is essential for developing drugs to target these proteins. Major issues related to activity assessment of transport proteins include availability of transporters, transport activity of transporters, and interactions between ligands and transporters. Researchers need to consider the physiological status of proteins (bound in lipid membranes or purified), availability and specificity of substrates, and the purpose of the activity assay (screening, identifying, or comparing substrates and inhibitors) before choosing appropriate assay strategies and techniques. Transport proteins bound in vesicular membranes can be assayed for transporting substrate across membranes by means of uptake assay or entrance counterflow assay. Alternatively, transport proteins can be assayed for interactions with ligands by using techniques such as isothermal titration calorimetry, nuclear magnetic resonance spectroscopy, or surface plasmon resonance. Other methods and techniques such as fluorometry, scintillation proximity assay, electrophysiological assay, or stopped-flow assay could also be used for activity assay of transport proteins. In this paper the major strategies and techniques for activity assessment of membrane transport proteins are reviewed.
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Affiliation(s)
- Hao Xie
- Department of Biological Science and Biotechnology, Institute of Science, Wuhan University of Technology, Wuhan 430070, China.
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Distinct subcellular distribution of delta-opioid receptor fused with various tags in PC12 cells. Neurochem Res 2008; 33:2028-34. [PMID: 18365312 DOI: 10.1007/s11064-008-9678-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2007] [Accepted: 03/13/2008] [Indexed: 10/22/2022]
Abstract
In small dorsal root ganglion neurons, delta-opioid receptors (DORs) have been found to be mainly distributed in the cytoplasm and often associated with the membrane of large dense-core vesicles (LDCVs) that contain neuropeptides. To study the distribution of DORs under various physiological or pharmacological conditions, the receptors fused with different tags are constructed, transfected into cells or animals, and examined with microscopy. In this study, we show that DOR with different tags have distinct patterns of subcellular distribution in neuroendocrine cells, PC12 cells. Both immunostaining and vesicle fraction analysis showed that the native DORs expressed in PC12 cells were mainly associated with LDCVs. In transfected PC12 cells, DOR tagged with Myc or hemagglutinin exhibited LDCV localization. However, DOR fused with GFP at N- or C-terminus was found to be mainly localized on the cell surface, and mediated the function of DOR agonist. Therefore, the distribution of DOR fused with GFP differs from the native DORs. These results suggest that the subcellular distribution of the receptor could be better presented by the fused tag with smaller molecular size.
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Rojek A, Praetorius J, Frøkiaer J, Nielsen S, Fenton RA. A Current View of the Mammalian Aquaglyceroporins. Annu Rev Physiol 2008; 70:301-27. [DOI: 10.1146/annurev.physiol.70.113006.100452] [Citation(s) in RCA: 246] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Aleksandra Rojek
- The Water and Salt Research Center, Institute of Anatomy, University of Aarhus, 8000 Aarhus C, Denmark;
| | - Jeppe Praetorius
- The Water and Salt Research Center, Institute of Anatomy, University of Aarhus, 8000 Aarhus C, Denmark;
| | - Jørgen Frøkiaer
- The Water and Salt Research Center, Institute of Anatomy, University of Aarhus, 8000 Aarhus C, Denmark;
| | - Søren Nielsen
- The Water and Salt Research Center, Institute of Anatomy, University of Aarhus, 8000 Aarhus C, Denmark;
| | - Robert A. Fenton
- The Water and Salt Research Center, Institute of Anatomy, University of Aarhus, 8000 Aarhus C, Denmark;
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43
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Presence and localization of aquaporin-6 in rat parotid acinar cells. Cell Tissue Res 2008; 332:73-80. [DOI: 10.1007/s00441-007-0558-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2007] [Accepted: 11/15/2007] [Indexed: 11/25/2022]
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Maue RA. Understanding ion channel biology using epitope tags: progress, pitfalls, and promise. J Cell Physiol 2007; 213:618-25. [PMID: 17849449 DOI: 10.1002/jcp.21259] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Epitope tags have been increasingly used to understand ion channel subunit assembly and interaction, trafficking, subcellular localization, and function in living cells. In particular, epitope tags have proven extremely useful for analyses of closely related, highly homologous channel subunits in endogenous cell contexts in vitro and in vivo, where multiple channel isoforms may be expressed. However, as the variety of epitope tags that have been used has expanded, and the use of tagged channel subunits has become increasingly sophisticated and widespread, there has also been an increase in the number of examples highlighting the potential problems associated with the use of epitope tags for ion channel studies. Described here are some of the epitope tags that have been used to study ion channel subunits, including the HA, FLAG, myc, His6, and green fluorescent protein (GFP) epitopes, as well as some of the applications and avenues of research in which they have proven advantageous. Potential pitfalls and caveats associated with the use of these epitope tags are also discussed, with an emphasis on the need to include careful characterization of epitope-tagged channel subunits as part of their construction. Finally, potential avenues for future investigation and the development of this approach are considered.
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Affiliation(s)
- Robert A Maue
- Department of Physiology, Dartmouth Medical School, Hanover, New Hampshire 03755, USA.
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Tritto S, Gastaldi G, Zelenin S, Grazioli M, Orsenigo MN, Ventura U, Laforenza U, Zelenina M. Osmotic water permeability of rat intestinal brush border membrane vesicles: involvement of aquaporin-7 and aquaporin-8 and effect of metal ions. Biochem Cell Biol 2007; 85:675-84. [DOI: 10.1139/o07-142] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Water channels AQP7 and AQP8 may be involved in transcellular water movement in the small intestine. We show that both AQP7 and AQP8 mRNA are expressed in rat small intestine. Immunoblot and immunohistochemistry experiments demonstrate that AQP7 and AQP8 proteins are present in the apical brush border membrane of intestinal epithelial cells. We investigated the effect of several metals and pH on the osmotic water permeability (Pf) of brush border membrane vesicles (BBMVs) and of AQP7 and AQP8 expressed in a cell line. Hg2+, Cu2+, and Zn2+caused a significant decrease in the BBMV Pf, whereas Ni2+and Li+had no effect. AQP8-transfected cells showed a reduction in Pfin the presence of Hg2+and Cu2+, whereas AQP7-transfected cells were insensitive to all tested metals. The Pfof both BBMVs and cells transfected with AQP7 and AQP8 was not affected by pH changes within the physiological range, and the Pfof BBMVs alone was not affected by phlorizin or amiloride. Our results indicate that AQP7 and AQP8 may play a role in water movement via the apical domain of small intestine epithelial cells. AQP8 may contribute to the water-imbalance-related clinical symptoms apparent after ingestion of high doses of Hg2+and Cu2+.
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Affiliation(s)
- Simona Tritto
- Department of Experimental Medicine, Section of Human Physiology, University of Pavia, Via Forlanini 6, I-27100 Pavia, Italy
- Nordic Centre of Excellence for Research in Water Imbalance Related Disorders, Department of Woman and Child Health, Karolinska Institutet, Stockholm, Sweden
- Department of Biomolecular Sciences and Biotechnologies, University of Milan, Italy
| | - Giulia Gastaldi
- Department of Experimental Medicine, Section of Human Physiology, University of Pavia, Via Forlanini 6, I-27100 Pavia, Italy
- Nordic Centre of Excellence for Research in Water Imbalance Related Disorders, Department of Woman and Child Health, Karolinska Institutet, Stockholm, Sweden
- Department of Biomolecular Sciences and Biotechnologies, University of Milan, Italy
| | - Sergey Zelenin
- Department of Experimental Medicine, Section of Human Physiology, University of Pavia, Via Forlanini 6, I-27100 Pavia, Italy
- Nordic Centre of Excellence for Research in Water Imbalance Related Disorders, Department of Woman and Child Health, Karolinska Institutet, Stockholm, Sweden
- Department of Biomolecular Sciences and Biotechnologies, University of Milan, Italy
| | - Monica Grazioli
- Department of Experimental Medicine, Section of Human Physiology, University of Pavia, Via Forlanini 6, I-27100 Pavia, Italy
- Nordic Centre of Excellence for Research in Water Imbalance Related Disorders, Department of Woman and Child Health, Karolinska Institutet, Stockholm, Sweden
- Department of Biomolecular Sciences and Biotechnologies, University of Milan, Italy
| | - Maria Novella Orsenigo
- Department of Experimental Medicine, Section of Human Physiology, University of Pavia, Via Forlanini 6, I-27100 Pavia, Italy
- Nordic Centre of Excellence for Research in Water Imbalance Related Disorders, Department of Woman and Child Health, Karolinska Institutet, Stockholm, Sweden
- Department of Biomolecular Sciences and Biotechnologies, University of Milan, Italy
| | - Ulderico Ventura
- Department of Experimental Medicine, Section of Human Physiology, University of Pavia, Via Forlanini 6, I-27100 Pavia, Italy
- Nordic Centre of Excellence for Research in Water Imbalance Related Disorders, Department of Woman and Child Health, Karolinska Institutet, Stockholm, Sweden
- Department of Biomolecular Sciences and Biotechnologies, University of Milan, Italy
| | - Umberto Laforenza
- Department of Experimental Medicine, Section of Human Physiology, University of Pavia, Via Forlanini 6, I-27100 Pavia, Italy
- Nordic Centre of Excellence for Research in Water Imbalance Related Disorders, Department of Woman and Child Health, Karolinska Institutet, Stockholm, Sweden
- Department of Biomolecular Sciences and Biotechnologies, University of Milan, Italy
| | - Marina Zelenina
- Department of Experimental Medicine, Section of Human Physiology, University of Pavia, Via Forlanini 6, I-27100 Pavia, Italy
- Nordic Centre of Excellence for Research in Water Imbalance Related Disorders, Department of Woman and Child Health, Karolinska Institutet, Stockholm, Sweden
- Department of Biomolecular Sciences and Biotechnologies, University of Milan, Italy
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Jeyaseelan K, Sepramaniam S, Armugam A, Wintour EM. Aquaporins: a promising target for drug development. Expert Opin Ther Targets 2007; 10:889-909. [PMID: 17105375 DOI: 10.1517/14728222.10.6.889] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Aquaporins (AQPs) are a family of small hydrophobic, integral membrane proteins that are expressed in all living organisms and play critical roles in controlling the water flow into and out of cells. So far, 13 different AQPs have been identified in mammals (AQP 0-12). AQPs have recently been implicated in various diseases such as cancer, cataract, brain oedema, gallstone disease and nephrogenic diabetes insipidus, as well as in the development of obesity and polycystic kidney disease. Interfering with the expression of AQPs will undoubtedly have therapeutic applications. Hence, in this review, the authors look at each AQP and its association with various pathological conditions in humans and demonstrate that they form potential targets for the treatment of such diseases.
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Affiliation(s)
- Kandiah Jeyaseelan
- Yong Loo Lin School of Medicine, National University of Singapore, Department of Biochemistry, 8 Medical Drive, 117597, Singapore.
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