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Banerjee S, Smith IM, Hengen AC, Stroka KM. Methods for studying mammalian aquaporin biology. Biol Methods Protoc 2023; 8:bpad031. [PMID: 38046463 PMCID: PMC10689382 DOI: 10.1093/biomethods/bpad031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 10/29/2023] [Accepted: 11/09/2023] [Indexed: 12/05/2023] Open
Abstract
Aquaporins (AQPs), transmembrane water-conducting channels, have earned a great deal of scrutiny for their critical physiological roles in healthy and disease cell states, especially in the biomedical field. Numerous methods have been implemented to elucidate the involvement of AQP-mediated water transport and downstream signaling activation in eliciting whole cell, tissue, and organ functional responses. To modulate these responses, other methods have been employed to investigate AQP druggability. This review discusses standard in vitro, in vivo, and in silico methods for studying AQPs, especially for biomedical and mammalian cell biology applications. We also propose some new techniques and approaches for future AQP research to address current gaps in methodology.
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Affiliation(s)
- Shohini Banerjee
- Fischell Department of Bioengineering, University of Maryland, MD 20742, United States
| | - Ian M Smith
- Fischell Department of Bioengineering, University of Maryland, MD 20742, United States
| | - Autumn C Hengen
- Fischell Department of Bioengineering, University of Maryland, MD 20742, United States
| | - Kimberly M Stroka
- Fischell Department of Bioengineering, University of Maryland, MD 20742, United States
- Marlene and Stewart Greenebaum Comprehensive Cancer Center, University of Maryland, Baltimore MD 21201, United States
- Biophysics Program, University of Maryland, MD 20742, United States
- Center for Stem Cell Biology and Regenerative Medicine, University of Maryland, Baltimore MD 21201, United States
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Xiong M, Li C, Wang W, Yang B. Protein Structure and Modification of Aquaporins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1398:15-38. [PMID: 36717484 DOI: 10.1007/978-981-19-7415-1_2] [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) allow water molecules and other small, neutral solutes to quickly pass through membrane. The protein structures of AQPs solved by crystallographic methods or cryo-electron microscopy technology show that AQP monomer consists of six membrane-spanning alpha-helices that form the central water-transporting pore. AQP monomers assemble to form tetramers, forming the functional units in the membrane, to transport water or other small molecules. The biological functions of AQPs are regulated by posttranslational modifications, e.g., phosphorylation, ubiquitination, glycosylation, subcellular distribution, degradation and protein interactions. Modifications of AQP combined with structural properties contribute to a better functional mechanism of AQPs. Insight into the molecular mechanisms responsible for AQP modifications as well as gating and transport properties proved to be fundamental to the development of new therapeutic targets or reliable diagnostic and prognostic biomarkers.
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Affiliation(s)
- Mengyao Xiong
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Chunling Li
- Institute of Hypertension and Kidney Research, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Weidong Wang
- Institute of Hypertension and Kidney Research, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China.
| | - Baoxue Yang
- School of Basic Medical Sciences, Peking University, Beijing, China.
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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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Abstract
Structurally, aquaporins (AQPs) are small channel proteins with monomers of ~ 30 kDa that are assembled as tetramers to form pores on cell membranes. Aquaporins mediate the conduction of water but at times also small solutes including glycerol across cell membranes and along osmotic gradients. Thirteen isoforms of AQPs have been reported in mammalian cells, and several of these are likely expressed in platelets. Osmotic swelling mediated by AQP1 sustains the calcium entry required for platelet phosphatidylserine exposure and microvesiculation, through calcium permeable stretch-activated or mechanosensitive cation channels. Notably, deletion of AQP1 diminishes platelet procoagulant membrane dynamics in vitro and arterial thrombosis in vivo, independent of platelet granule secretion and without affecting hemostasis. Water entry into platelets promotes procoagulant activity, and AQPs may also be critical for the initiation and progression of venous thrombosis. Platelet AQPs may therefore represent valuable targets for future development of a new class of antithrombotics, namely, anti-procoagulant antithrombotics, that are mechanistically distinct from current antithrombotics. However, the structure of AQPs does not make for easy targeting of these channels, hence they remain elusive drug targets. Nevertheless, thrombosis data in animal models provide compelling reasons to continue the pursuit of AQP-targeted antithrombotics. In this review, we discuss the role of aquaporins in platelet secretion, aggregation and procoagulation, the challenge of drugging AQPs, and the prospects of targeting AQPs for arterial and venous antithrombosis.
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Affiliation(s)
- Ejaife O Agbani
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Alberta, Canada
| | - Alastair W Poole
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, England, UK
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Alkhalifa H, Mohammed F, Taurin S, Greish K, Taha S, Fredericks S. Inhibition of aquaporins as a potential adjunct to breast cancer cryotherapy. Oncol Lett 2021; 21:458. [PMID: 33907568 PMCID: PMC8063341 DOI: 10.3892/ol.2021.12719] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 03/02/2021] [Indexed: 12/20/2022] Open
Abstract
Cryoablation is an emerging type of treatment for cancer. The sensitization of tumors using cryosensitizing agents prior to treatment enhances ablation efficiency and may improve clinical outcomes. Water efflux, which is regulated by aquaporin channels, contributes to cancer cell damage achieved through cryoablation. An increase in aquaporin (AQP) 3 is cryoprotective, whereas its inhibition augments cryodamage. The present study aimed to investigate aquaporin (AQP1, AQP3 and AQP5) gene expression and cellular localization in response to cryoinjury. Cultured breast cancer cells (MDA-MB-231 and MCF-7) were exposed to freezing to induce cryoinjury. RNA and protein extracts were then analyzed using reverse transcription-quantitative PCR and western blotting, respectively. Localization of aquaporins was studied using immunocytochemistry. Additionally, cells were transfected with small interfering RNA to silence aquaporin gene expression and cell viability was assessed using the Sulforhodamine B assay. Cryoinjury did not influence gene expression of AQPs, except for a 4-fold increase of AQP1 expression in MDA-MD-231 cells. There were no clear differences in AQP protein expression for either cell lines upon exposure to frozen and non-frozen temperatures, with the exception of fainter AQP5 bands for non-frozen MCF-7 cells. The exposure of cancer cells to freezing temperatures altered the localization of AQP1 and AQP3 proteins in both MCF-7 and MDA-MD-231 cells. The silencing of AQP1, AQP3 and AQP5 exacerbated MDA-MD-231 cell damage associated with freezing compared with control siRNA. This was also observed with AQP3 and AQP5 silencing in MCF-7 cells. Inhibition of aquaporins may potentially enhance cryoinjury. This cryosensitizing process may be used as an adjunct to breast cancer cryotherapy, especially in the border area targeted by cryoablation where freezing temperatures are not cold enough to induce cellular damage.
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Affiliation(s)
- Haifa Alkhalifa
- Department of Basic Medical Sciences, Royal College of Surgeons in Ireland, Medical University of Bahrain, Adliya 15503, Kingdom of Bahrain
- Department of Science, New York University Abu Dhabi, Abu Dhabi 129188, United Arab Emirates
| | - Fatima Mohammed
- Department of Basic Medical Sciences, Royal College of Surgeons in Ireland, Medical University of Bahrain, Adliya 15503, Kingdom of Bahrain
| | - Sebastien Taurin
- Department of Molecular Medicine, College of Medicine and Medical Sciences, Princess Al-Jawhara Centre for Molecular Medicine, Arabian Gulf University, Segaya, Manama 328, Kingdom of Bahrain
| | - Khaled Greish
- Department of Molecular Medicine, College of Medicine and Medical Sciences, Princess Al-Jawhara Centre for Molecular Medicine, Arabian Gulf University, Segaya, Manama 328, Kingdom of Bahrain
| | - Safa Taha
- Department of Molecular Medicine, College of Medicine and Medical Sciences, Princess Al-Jawhara Centre for Molecular Medicine, Arabian Gulf University, Segaya, Manama 328, Kingdom of Bahrain
| | - Salim Fredericks
- Department of Basic Medical Sciences, Royal College of Surgeons in Ireland, Medical University of Bahrain, Adliya 15503, Kingdom of Bahrain
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Verbeek SF, Awasthi N, Teiwes NK, Mey I, Hub JS, Janshoff A. How arginine derivatives alter the stability of lipid membranes: dissecting the roles of side chains, backbone and termini. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2021; 50:127-142. [PMID: 33661339 PMCID: PMC8071801 DOI: 10.1007/s00249-021-01503-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 01/08/2021] [Accepted: 01/19/2021] [Indexed: 12/22/2022]
Abstract
Arginine (R)-rich peptides constitute the most relevant class of cell-penetrating peptides and other membrane-active peptides that can translocate across the cell membrane or generate defects in lipid bilayers such as water-filled pores. The mode of action of R-rich peptides remains a topic of controversy, mainly because a quantitative and energetic understanding of arginine effects on membrane stability is lacking. Here, we explore the ability of several oligo-arginines R[Formula: see text] and of an arginine side chain mimic R[Formula: see text] to induce pore formation in lipid bilayers employing MD simulations, free-energy calculations, breakthrough force spectroscopy and leakage assays. Our experiments reveal that R[Formula: see text] but not R[Formula: see text] reduces the line tension of a membrane with anionic lipids. While R[Formula: see text] peptides form a layer on top of a partly negatively charged lipid bilayer, R[Formula: see text] leads to its disintegration. Complementary, our simulations show R[Formula: see text] causes membrane thinning and area per lipid increase beside lowering the pore nucleation free energy. Model polyarginine R[Formula: see text] similarly promoted pore formation in simulations, but without overall bilayer destabilization. We conclude that while the guanidine moiety is intrinsically membrane-disruptive, poly-arginines favor pore formation in negatively charged membranes via a different mechanism. Pore formation by R-rich peptides seems to be counteracted by lipids with PC headgroups. We found that long R[Formula: see text] and R[Formula: see text] but not short R[Formula: see text] reduce the free energy of nucleating a pore. In short R[Formula: see text], the substantial effect of the charged termini prevent their membrane activity, rationalizing why only longer [Formula: see text] are membrane-active.
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Affiliation(s)
- Sarah F. Verbeek
- Department of Chemistry, Institute of Physical Chemistry, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
| | - Neha Awasthi
- Institute of Microbiology and Genetics, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
| | - Nikolas K. Teiwes
- Department of Chemistry, Institute of Physical Chemistry, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
| | - Ingo Mey
- Department of Chemistry, Institute of Physical Chemistry, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
| | - Jochen S. Hub
- Institute of Microbiology and Genetics, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
- Theoretical Physics and Center for Biophyics, Saarland University, 66123 Saarbrücken, Germany
| | - Andreas Janshoff
- Department of Chemistry, Institute of Physical Chemistry, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
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Zhang Y, Liu D, Xue F, Yu H, Wu H, Cui X, Zhang X, Wang H. Anti-Malignant Ascites Effect of Total Diterpenoids from Euphorbiae Ebracteolatae Radix Is Attributable to Alterations of Aquaporins via Inhibiting PKC Activity in the Kidney. Molecules 2021; 26:molecules26040942. [PMID: 33578967 PMCID: PMC7916655 DOI: 10.3390/molecules26040942] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/05/2021] [Accepted: 02/07/2021] [Indexed: 01/16/2023] Open
Abstract
This study evaluated the anti-ascites effect of total diterpenoids extracted from Euphorbiae ebracteolatae Radix (TDEE) on malignant ascitic mice and elucidated its underlying mechanism. TDEE was extracted by dichloromethane and subjected to column chromatography. The purity of six diterpenoids isolated from TDEE was determined to be 77.18% by HPLC. TDEE (3 and 0.6 g raw herbs/kg, p.o.) reduced ascites and increased urine output. Meanwhile, analysis of tumor cell viability, cycle and apoptosis indicated that TDEE had no antitumor activity. In addition, the expression levels of aquaporins (AQPs) and the membrane translocation levels of protein kinase C (PKC) α and PKCβ in kidney and cells were measured. TDEE reduced the levels of AQP1–4, and inhibited PKCβ expression in membrane fraction. Four main diterpenoids, except compound 2, reduced AQP1 level in human kidney-2 cells. Compounds 4 and 5 inhibited AQP2–4 expression in murine inner medullary collecting duct cells. The diterpenoid-induced inhibition of AQP1–4 expression was blocked by phorbol-12-myristate-13-acetate (PMA; agonist of PKC). The diterpenoids from TDEE are the main anti-ascites components. The anti-ascites effect of diterpenoids may be associated with alterations in AQPs in the kidneys to promote diuresis. The inhibition of AQP1–4 expression by TDEE is related to the inhibition of PKCβ activation.
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Affiliation(s)
- Yuanbin Zhang
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China; (Y.Z.); (D.L.); (F.X.); (X.C.); (X.Z.); (H.W.)
| | - Dongfang Liu
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China; (Y.Z.); (D.L.); (F.X.); (X.C.); (X.Z.); (H.W.)
| | - Fan Xue
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China; (Y.Z.); (D.L.); (F.X.); (X.C.); (X.Z.); (H.W.)
| | - Hongli Yu
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China; (Y.Z.); (D.L.); (F.X.); (X.C.); (X.Z.); (H.W.)
- Jiangsu Key Laboratory of Chinese Medicine Processing, Nanjing University of Chinese Medicine, Nanjing 210023, China
- Engineering Center of State Ministry of Education for Standardization of Chinese Medicine Processing, Nanjing 210023, China
- State Key Laboratory Cultivation Base for TCM Quality and Efficacy, Nanjing University of Chinese Medicine, Nanjing 210023, China
- Correspondence: or (H.Y.); or (H.W.); Tel.: +86-025-8679-8281 (H.Y.); +86-025-8581-1206 (H.W.)
| | - Hao Wu
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China; (Y.Z.); (D.L.); (F.X.); (X.C.); (X.Z.); (H.W.)
- Jiangsu Key Laboratory of Chinese Medicine Processing, Nanjing University of Chinese Medicine, Nanjing 210023, China
- Engineering Center of State Ministry of Education for Standardization of Chinese Medicine Processing, Nanjing 210023, China
- State Key Laboratory Cultivation Base for TCM Quality and Efficacy, Nanjing University of Chinese Medicine, Nanjing 210023, China
- Correspondence: or (H.Y.); or (H.W.); Tel.: +86-025-8679-8281 (H.Y.); +86-025-8581-1206 (H.W.)
| | - Xiaobing Cui
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China; (Y.Z.); (D.L.); (F.X.); (X.C.); (X.Z.); (H.W.)
| | - Xingde Zhang
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China; (Y.Z.); (D.L.); (F.X.); (X.C.); (X.Z.); (H.W.)
| | - Hepeng Wang
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China; (Y.Z.); (D.L.); (F.X.); (X.C.); (X.Z.); (H.W.)
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Ou WF, Huang WH, Chiu HF, Mao YC, Wen MC, Chen CH, Hung SJ, Wu MJ, Wu CL, Chao WC. Clinical manifestation of multiple wasp stings with details of whole transcriptome analysis: Two case reports. Medicine (Baltimore) 2021; 100:e24492. [PMID: 33530269 PMCID: PMC7850695 DOI: 10.1097/md.0000000000024492] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 12/28/2020] [Accepted: 01/07/2021] [Indexed: 01/05/2023] Open
Abstract
INTRODUCTION Multiple wasp stings is an emergency result from systemic reactions to the toxin with a wide range of manifestations, and we presented 2 patients with distinct clinical and transcriptomic findings. PATIENT CONCERNS Two patients without systemic disease presented with nearly 90 painful papules after attacked by a swarm of wasps (Vespa basalis). DIAGNOSIS Patient 1 was a 44-year-old healthy male whose clinical manifestations mainly comprised hemolysis, hepatic injury, rhabdomyolysis, and acute kidney injury. Patient 2 was a 49-year-old healthy female who presented with severe acute respiratory distress syndrome (ARDS) in addition to certain clinical manifestations that were also found in patient 1. We used ribo- nucleic acid sequencing (RNA-Seq) to characterize the inflammatory responses of 2 patients with distinct clinical manifestations after multiple wasp stings. INTERVENTIONS Both 2 patients received 5 sessions of plasmapheresis, and patient-1 further received mechanical ventilation for 8 days as well as 8 sessions of hemodialysis until day 17. OUTCOMES Both patients recovered uneventfully after the aforementioned management. We used RNA-Seq to demonstrate a largely regulated neutrophil-predominated immune response in patient 1. In patient 2, we found a profound neutrophilc response on week 1 and a robust neutrophilic as well as pro-inflammatory responses on week 2. Furthermore, we found increased expression of signals that were associated with renal system process on week 2. CONCLUSION In conclusion, we report 2 patients who manifested with shared and distinct presentations after an attack by the same swarm of wasps. Both patients had hemolysis, rhabdomyolysis, hepatic injury and acute kidney injury, and 1 patient had ARDS. The whole transcriptomic analyses were consistent with the distinct clinical manifestation, and these results suggest the potential of RNA-Sequencing to disentangle complex inflammatory responses in patients with multiple wasp stings. Plasmapheresis and corticosteroid were administered to both patients and case 2 also underwent 8 sessions of hemodialysis.
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Affiliation(s)
| | | | - Hsien-Fu Chiu
- Division of Nephrology, Department of Internal Medicine
| | - Yan-Chiao Mao
- Division of Clinical Toxicology, Department of Emergency Medicine
| | - Mei-Chin Wen
- Department of Pathology and Laboratory Medicine, Taichung Veterans General Hospital
| | - Cheng-Hsu Chen
- Division of Nephrology, Department of Internal Medicine
- Department of Life Science, Tunghai University
| | - Sheng-Jou Hung
- Department of Medical Research, Taichung Veterans General Hospital
| | - Ming-Ju Wu
- Division of Nephrology, Department of Internal Medicine
- School of Medicine, Chung Shan Medical University
- Rong Hsing Research Center for Translational Medicine, Institute of Biomedical Science, College of Life Science, National Chung Hsing University
- Graduate Institute of Clinical Medical Science, School of Medicine, China Medical University
| | - Chieh-Liang Wu
- Department of Critical Care Medicine, Taichung Veterans General Hospital
- Department of Industrial Engineering and Enterprise Information
| | - Wen-Cheng Chao
- Department of Critical Care Medicine, Taichung Veterans General Hospital
- Department of Computer Science, Tunghai University, Taichung, Taiwan
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Qiu J, McGaughey SA, Groszmann M, Tyerman SD, Byrt CS. Phosphorylation influences water and ion channel function of AtPIP2;1. PLANT, CELL & ENVIRONMENT 2020; 43:2428-2442. [PMID: 32678928 DOI: 10.1111/pce.13851] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 07/09/2020] [Accepted: 07/09/2020] [Indexed: 05/24/2023]
Abstract
The phosphorylation state of two serine residues within the C-terminal domain of AtPIP2;1 (S280, S283) regulates its plasma membrane localization in response to salt and osmotic stress. Here, we investigated whether the phosphorylation state of S280 and S283 also influence AtPIP2;1 facilitated water and cation transport. A series of single and double S280 and S283 phosphomimic and phosphonull AtPIP2;1 mutants were tested in heterologous systems. In Xenopus laevis oocytes, phosphomimic mutants AtPIP2;1 S280D, S283D, and S280D/S283D had significantly greater ion conductance for Na+ and K+ , whereas the S280A single phosphonull mutant had greater water permeability. We observed a phosphorylation-dependent inverse relationship between AtPIP2;1 water and ion transport with a 10-fold change in both. The results revealed that phosphorylation of S280 and S283 influences the preferential facilitation of ion or water transport by AtPIP2;1. The results also hint that other regulatory sites play roles that are yet to be elucidated. Expression of the AtPIP2;1 phosphorylation mutants in Saccharomyces cerevisiae confirmed that phosphorylation influences plasma membrane localization, and revealed higher Na+ accumulation for S280A and S283D mutants. Collectively, the results show that phosphorylation in the C-terminal domain of AtPIP2;1 influences its subcellular localization and cation transport capacity.
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Affiliation(s)
- Jiaen Qiu
- ARC Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, The University of Adelaide, Adelaide, Australia
| | - Samantha A McGaughey
- ARC Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, The University of Adelaide, Adelaide, Australia
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, Australia
| | - Michael Groszmann
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, Australia
| | - Stephen D Tyerman
- ARC Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, The University of Adelaide, Adelaide, Australia
| | - Caitlin S Byrt
- ARC Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, The University of Adelaide, Adelaide, Australia
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, Australia
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Quintana JF, Bueren-Calabuig J, Zuccotto F, de Koning HP, Horn D, Field MC. Instability of aquaglyceroporin (AQP) 2 contributes to drug resistance in Trypanosoma brucei. PLoS Negl Trop Dis 2020; 14:e0008458. [PMID: 32644992 PMCID: PMC7413563 DOI: 10.1371/journal.pntd.0008458] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 08/07/2020] [Accepted: 06/05/2020] [Indexed: 12/26/2022] Open
Abstract
Defining mode of action is vital for both developing new drugs and predicting potential resistance mechanisms. Sensitivity of African trypanosomes to pentamidine and melarsoprol is predominantly mediated by aquaglyceroporin 2 (TbAQP2), a channel associated with water/glycerol transport. TbAQP2 is expressed at the flagellar pocket membrane and chimerisation with TbAQP3 renders parasites resistant to both drugs. Two models for how TbAQP2 mediates pentamidine sensitivity have emerged; that TbAQP2 mediates pentamidine translocation across the plasma membrane or via binding to TbAQP2, with subsequent endocytosis and presumably transport across the endosomal/lysosomal membrane, but as trafficking and regulation of TbAQPs is uncharacterised this remains unresolved. We demonstrate that TbAQP2 is organised as a high order complex, is ubiquitylated and is transported to the lysosome. Unexpectedly, mutation of potential ubiquitin conjugation sites, i.e. cytoplasmic-oriented lysine residues, reduced folding and tetramerization efficiency and triggered ER retention. Moreover, TbAQP2/TbAQP3 chimerisation, as observed in pentamidine-resistant parasites, also leads to impaired oligomerisation, mislocalisation and increased turnover. These data suggest that TbAQP2 stability is highly sensitive to mutation and that instability contributes towards the emergence of drug resistance.
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Affiliation(s)
- Juan F. Quintana
- School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, United Kingdom
| | - Juan Bueren-Calabuig
- School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, United Kingdom
| | - Fabio Zuccotto
- School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, United Kingdom
| | - Harry P. de Koning
- Institute of Infection, Immunity, and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - David Horn
- School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, United Kingdom
| | - Mark C. Field
- School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, United Kingdom
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Ceske Budejovice, Czech Republic
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Ota T, Kuwahara M, Fan S, Terada Y, Akiba T, Sasaki S, Marumo F. Expression of Aquaporin-1 in the Peritoneal Tissues: Localization and Regulation by Hyperosmolality. Perit Dial Int 2020. [DOI: 10.1177/089686080202200303] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
ObjectiveThe purpose of this study was to determine the localization of the aquaporin-1 (AQP1) water channel in peritoneal tissues and the effect of hyperosmolality on the peritoneal expression and function of AQP1.MethodsImmunohistochemical localization of AQP1 was identified in rat peritoneal tissues. Cultured rat peritoneal mesothelial cells (RPMCs) were exposed to hyperosmolality by adding 4% glucose to the culture medium. After 1 hour, 4 hours, 24 hours, and 48 hours, AQP1 was identified by semiquantitative immunoblot and immunocytochemistry. Osmotic water permeability was measured using a light-scattering method.ResultsImmunohistochemistry of rat peritoneal tissues showed the presence of AQP1 in mesothelial cells, venular endothelial cells, and capillary endothelial cells, but not in arteriole and interstitial cells. Semiquantitative immunoblot revealed that exposure to hyperosmolality significantly increased AQP1 expression after 24 hours in whole RPMC lysates (3.3-fold at 24 hours and 3.9-fold at 48 hours). Consistent with the immunoblot, osmotic water permeability of RPMC was augmented 1.7-fold and 2.7-fold after 1 hour and 24 hours, respectively, in a hyperosmotic environment. In RPMC membrane fractions, AQP1 expression was significantly increased after 1 hour of exposure to hyperosmolality (3.9-fold at 1 hour, 7.1-fold at 4 hours, and 8.7-fold at 24 hours). Immunocytochemistry of RPMCs showed that AQP1 was gradually redistributed from the perinuclear area to the peripheral cytoplasm, and then to the plasma membrane after a 1-hour hyperosmotic challenge, suggesting hyperosmolality-induced translocation of AQP1. Upregulation of AQP1 was also observed in the omentum of rats loaded intraperitoneally with hyperosmotic dialysate every day for 10 weeks.ConclusionAQP1 is widely distributed in the peritoneal cavity and may provide the major aqueous pathway across the peritoneal barrier. In addition, our findings suggested that hyperosmolality increases AQP1-dependent water permeability in peritoneal tissues by regulating the translocation and synthesis of AQP1 protein.
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Affiliation(s)
- Tomoko Ota
- Department of Blood Purification and Department of Homeostasis Medicine and Nephrology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Michio Kuwahara
- Department of Blood Purification and Department of Homeostasis Medicine and Nephrology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Shuling Fan
- Department of Blood Purification and Department of Homeostasis Medicine and Nephrology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Yoshio Terada
- Department of Blood Purification and Department of Homeostasis Medicine and Nephrology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Takashi Akiba
- Department of Blood Purification and Department of Homeostasis Medicine and Nephrology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Sei Sasaki
- Department of Blood Purification and Department of Homeostasis Medicine and Nephrology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Fumiaki Marumo
- Department of Blood Purification and Department of Homeostasis Medicine and Nephrology, Tokyo Medical and Dental University, Tokyo, Japan
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12
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Rauen K, Pop V, Trabold R, Badaut J, Plesnila N. Vasopressin V 1a Receptors Regulate Cerebral Aquaporin 1 after Traumatic Brain Injury. J Neurotrauma 2020; 37:665-674. [PMID: 31547764 PMCID: PMC7045352 DOI: 10.1089/neu.2019.6653] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Brain edema formation contributes to secondary brain damage and unfavorable outcome after traumatic brain injury (TBI). Aquaporins (AQP), highly selective water channels, are involved in the formation of post-trauma brain edema; however, their regulation is largely unknown. Because vasopressin receptors are involved in AQP-mediated water transport in the kidney and inhibition of V1a receptors reduces post-trauma brain edema formation, we hypothesize that cerebral AQPs may be regulated by V1a receptors. Cerebral Aqp1 and Aqp4 messenger ribonucleic acid (mRNA) and AQP1 and AQP4 protein levels were quantified in wild-type and V1a receptor knockout (V1a-/-) mice before and 15 min, 1, 3, 6, 12, or 24 h after experimental TBI by controlled cortical impact. In non-traumatized mice, we found AQP1 and AQP4 expression in cortical neurons and astrocytes, respectively. Experimental TBI had no effect on Aqp4 mRNA or AQP4 protein expression, but increased Aqp1 mRNA (p < 0.05) and AQP1 protein expression (p < 0.05) in both hemispheres. The Aqp1 mRNA and AQP1 protein regulation was blunted in V1a receptor knockout mice. The V1a receptors regulate cerebral AQP1 expression after experimental TBI, thereby unraveling the molecular mechanism by which these receptors may mediate brain edema formation after TBI.
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Affiliation(s)
- Katrin Rauen
- Laboratory of Experimental Neurosurgery, Department of Neurosurgery & Institute for Surgical Research, University of Munich Medical Center, Munich, Germany
- Institute for Stroke and Dementia Research (ISD), University of Munich Medical Center, Munich, Germany
- University Hospital of Psychiatry Zurich, Department of Geriatric Psychiatry & Institute for Regenerative Medicine, University of Zurich, Zurich, Switzerland
| | - Viorela Pop
- Department of Pediatrics, Loma Linda University School of Medicine, Loma Linda, California
| | - Raimund Trabold
- Laboratory of Experimental Neurosurgery, Department of Neurosurgery & Institute for Surgical Research, University of Munich Medical Center, Munich, Germany
| | - Jerome Badaut
- Department of Pediatrics, Loma Linda University School of Medicine, Loma Linda, California
- Aquitaine Institute for Cognitive and Integrative Neuroscience, University of Bordeaux, Bordeaux, France
| | - Nikolaus Plesnila
- Laboratory of Experimental Neurosurgery, Department of Neurosurgery & Institute for Surgical Research, University of Munich Medical Center, Munich, Germany
- Institute for Stroke and Dementia Research (ISD), University of Munich Medical Center, Munich, Germany
- Munich Cluster for Systems Neurology (Synergy), Munich, Germany
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13
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Skowronska A, Tanski D, Jaskiewicz L, Skowronski MT. Modulation by steroid hormones and other factors on the expression of aquaporin-1 and aquaporin-5. VITAMINS AND HORMONES 2019; 112:209-242. [PMID: 32061342 DOI: 10.1016/bs.vh.2019.08.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- A Skowronska
- Department of Human Physiology, School of Medicine, University of Warmia and Mazury in Olsztyn, Olsztyn, Poland.
| | - D Tanski
- Department of Anatomy and Animal Physiology, Faculty of Biology and Biotechnology, University of Warmia and Mazury in Olsztyn, Olsztyn, Poland
| | - L Jaskiewicz
- Department of Human Physiology, School of Medicine, University of Warmia and Mazury in Olsztyn, Olsztyn, Poland
| | - M T Skowronski
- Veterinary Center, University of Nicolaus Copernicus, Torun, Poland
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14
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Nesverova V, Törnroth-Horsefield S. Phosphorylation-Dependent Regulation of Mammalian Aquaporins. Cells 2019; 8:cells8020082. [PMID: 30678081 PMCID: PMC6406877 DOI: 10.3390/cells8020082] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 01/17/2019] [Accepted: 01/21/2019] [Indexed: 12/26/2022] Open
Abstract
Water homeostasis is fundamental for cell survival. Transport of water across cellular membranes is governed by aquaporins—tetrameric integral membrane channels that are highly conserved throughout the prokaryotic and eukaryotic kingdoms. In eukaryotes, specific regulation of these channels is required and is most commonly carried out by shuttling the protein between cellular compartments (trafficking) or by opening and closing the channel (gating). Structural and functional studies have revealed phosphorylation as a ubiquitous mechanism in aquaporin regulation by both regulatory processes. In this review we summarize what is currently known about the phosphorylation-dependent regulation of mammalian aquaporins. Focusing on the water-specific aquaporins (AQP0–AQP5), we discuss how gating and trafficking are controlled by phosphorylation and how phosphorylation affects the binding of aquaporins to regulatory proteins, thereby highlighting structural details and dissecting the contribution of individual phosphorylated residues when possible. Our aim is to provide an overview of the mechanisms behind how aquaporin phosphorylation controls cellular water balance and to identify key areas where further studies are needed.
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Affiliation(s)
- Veronika Nesverova
- Department of Biochemistry and Structural Biology, Center for Molecular Protein Science, Lund University, Box 124, 221 00 Lund, Sweden.
| | - Susanna Törnroth-Horsefield
- Department of Biochemistry and Structural Biology, Center for Molecular Protein Science, Lund University, Box 124, 221 00 Lund, Sweden.
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15
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Halsey AM, Conner AC, Bill RM, Logan A, Ahmed Z. Aquaporins and Their Regulation after Spinal Cord Injury. Cells 2018; 7:E174. [PMID: 30340399 PMCID: PMC6210264 DOI: 10.3390/cells7100174] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 10/13/2018] [Accepted: 10/15/2018] [Indexed: 11/16/2022] Open
Abstract
After injury to the spinal cord, edema contributes to the underlying detrimental pathophysiological outcomes that lead to worsening of function. Several related membrane proteins called aquaporins (AQPs) regulate water movement in fluid transporting tissues including the spinal cord. Within the cord, AQP1, 4 and 9 contribute to spinal cord injury (SCI)-induced edema. AQP1, 4 and 9 are expressed in a variety of cells including astrocytes, neurons, ependymal cells, and endothelial cells. This review discusses some of the recent findings of the involvement of AQP in SCI and highlights the need for further study of these proteins to develop effective therapies to counteract the negative effects of SCI-induced edema.
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Affiliation(s)
- Andrea M Halsey
- Neuroscience and Ophthalmology, Institute of Inflammation and Ageing, University of Birmingham, Birmingham, B15 2TT, UK.
| | - Alex C Conner
- Institute of Clinical Sciences, University of Birmingham, Birmingham B15 2TT, UK.
| | - Roslyn M Bill
- School of Life and Health Sciences, Aston University, Birmingham B4 7ET, UK.
| | - Ann Logan
- Neuroscience and Ophthalmology, Institute of Inflammation and Ageing, University of Birmingham, Birmingham, B15 2TT, UK.
| | - Zubair Ahmed
- Neuroscience and Ophthalmology, Institute of Inflammation and Ageing, University of Birmingham, Birmingham, B15 2TT, UK.
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16
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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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17
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Kourghi M, Pei JV, De Ieso ML, Nourmohammadi S, Chow PH, Yool AJ. Fundamental structural and functional properties of Aquaporin ion channels found across the kingdoms of life. Clin Exp Pharmacol Physiol 2018; 45:401-409. [PMID: 29193257 DOI: 10.1111/1440-1681.12900] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 11/06/2017] [Accepted: 11/16/2017] [Indexed: 01/09/2023]
Abstract
Aquaporin (AQP) channels in the major intrinsic protein (MIP) family are known to facilitate transmembrane water fluxes in prokaryotes and eukaryotes. Some classes of AQPs also conduct ions, glycerol, urea, CO2 , nitric oxide, and other small solutes. Ion channel activity has been demonstrated for mammalian AQPs 0, 1, 6, Drosophila Big Brain (BIB), soybean nodulin 26, and rockcress AtPIP2;1. More classes are likely to be discovered. Newly identified blockers are providing essential tools for establishing physiological roles of some of the AQP dual water and ion channels. For example, the arylsulfonamide AqB011 which selectively blocks the central ion pore of mammalian AQP1 has been shown to impair migration of HT29 colon cancer cells. Traditional herbal medicines are sources of selective AQP1 inhibitors that also slow cancer cell migration. The finding that plant AtPIP2;1 expressed in root epidermal cells mediates an ion conductance regulated by calcium and protons provided insight into molecular mechanisms of environmental stress responses. Expression of lens MIP (AQP0) is essential for maintaining the structure, integrity and transparency of the lens, and Drosophila BIB contributes to neurogenic signalling pathways to control the developmental fate of fly neuroblast cells; however, the ion channel roles remain to be defined for MIP and BIB. A broader portfolio of pharmacological agents is needed to investigate diverse AQP ion channel functions in situ. Understanding the dual water and ion channel roles of AQPs could inform the development of novel agents for rational interventions in diverse challenges from agriculture to human health.
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Affiliation(s)
- Mohamad Kourghi
- Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| | - Jinxin V Pei
- Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| | - Michael L De Ieso
- Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| | | | - Pak Hin Chow
- Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| | - Andrea J Yool
- Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
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18
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Sutka M, Amodeo G, Ozu M. Plant and animal aquaporins crosstalk: what can be revealed from distinct perspectives. Biophys Rev 2017; 9:545-562. [PMID: 28871493 DOI: 10.1007/s12551-017-0313-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 08/02/2017] [Indexed: 01/03/2023] Open
Abstract
Aquaporins (AQPs) can be revisited from a distinct and complementary perspective: the outcome from analyzing them from both plant and animal studies. (1) The approach in the study. Diversity found in both kingdoms contrasts with the limited number of crystal structures determined within each group. While the structure of almost half of mammal AQPs was resolved, only a few were resolved in plants. Strikingly, the animal structures resolved are mainly derived from the AQP2-lineage, due to their important roles in water homeostasis regulation in humans. The difference could be attributed to the approach: relevance in animal research is emphasized on pathology and in consequence drug screening that can lead to potential inhibitors, enhancers and/or regulators. By contrast, studies on plants have been mainly focused on the physiological role that AQPs play in growth, development and stress tolerance. (2) The transport capacity. Besides the well-described AQPs with high water transport capacity, large amount of evidence confirms that certain plant AQPs can carry a large list of small solutes. So far, animal AQP list is more restricted. In both kingdoms, there is a great amount of evidence on gas transport, although there is still an unsolved controversy around gas translocation as well as the role of the central pore of the tetramer. (3) More roles than expected. We found it remarkable that the view of AQPs as specific channels has evolved first toward simple transporters to molecules that can experience conformational changes triggered by biochemical and/or mechanical signals, turning them also into signaling components and/or behave as osmosensor molecules.
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Affiliation(s)
- Moira Sutka
- Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires e Instituto de Biodiversidad y Biología Experimental, Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Gabriela Amodeo
- Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires e Instituto de Biodiversidad y Biología Experimental, Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina.
| | - Marcelo Ozu
- Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires e Instituto de Biodiversidad y Biología Experimental, Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina.
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19
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Patil R, Wang H, Sharif NA, Mitra A. Aquaporins: Novel Targets for Age-Related Ocular Disorders. J Ocul Pharmacol Ther 2017. [PMID: 28632458 DOI: 10.1089/jop.2017.0024] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Aquaporins (AQPs), a large family of membrane protein channels that facilitate transport of water and other small solutes, play important roles in physiological functions and human diseases. Up till now, 13 types of AQPs, numbered 0 through 12, have been identified in various mammalian tissues. Homologous genes for AQPs in amphibians, insects, and bacteria highlight the evolutionary conservation and, thus, the importance of these membrane channels. Many members of the AQP family are expressed in the eye. AQP1, which is a water-selective channel, is expressed in the anterior chamber (cornea, ciliary body, trabecular meshwork) and posterior chamber (retina and microvessels in choroid), controlling the fluid homeostasis in the eye. Mice knockout studies have indicated that AQP1 plays an important function in the eye by suggesting its role in aqueous humor dynamics and retina angiogenesis. This review will focus on the role of AQP1 as a novel target for ocular disorders such as glaucoma and age-related macular degeneration, and it will discuss challenges and advances in identifying modulators of AQP1 function that could be useful in clinical applications.
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Affiliation(s)
- Rajkumar Patil
- 1 Singapore Eye Research Institute , Singapore, Singapore
- 2 Ophthalmology & Visual Sciences Academic Clinical Program (Eye ACP), Duke-NUS Medical School , Singapore, Singapore
| | - Haishan Wang
- 3 Institute of Molecular and Cell Biology , A*STAR, Singapore, Singapore
| | | | - Alok Mitra
- 5 School of Biological Sciences, University of Auckland , Auckland, New Zealand
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20
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Zhao ZA, Li P, Ye SY, Ning YL, Wang H, Peng Y, Yang N, Zhao Y, Zhang ZH, Chen JF, Zhou YG. Perivascular AQP4 dysregulation in the hippocampal CA1 area after traumatic brain injury is alleviated by adenosine A 2A receptor inactivation. Sci Rep 2017; 7:2254. [PMID: 28533515 PMCID: PMC5440401 DOI: 10.1038/s41598-017-02505-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 04/12/2017] [Indexed: 12/14/2022] Open
Abstract
Traumatic brain injury (TBI) can induce cognitive dysfunction due to the regional accumulation of hyperphosphorylated tau protein (p-tau). However, the factors that cause p-tau to concentrate in specific brain regions remain unclear. Here, we show that AQP4 polarization in the perivascular astrocytic end feet was impaired after TBI, which was most prominent in the ipsilateral brain tissue surrounding the directly impacted region and the contralateral hippocampal CA1 area and was accompanied by increased local p-tau, changes in dendritic spine density and morphology, and upregulation of the adenosine A2A receptor (A2AR). The critical role of the A2AR signaling in these pathological changes was confirmed by alleviation of the impairment of AQP4 polarity and accumulation of p-tau in the contralateral CA1 area in A2AR knockout mice. Given that p-tau can be released to the extracellular space and that the astroglial water transport via AQP4 is involved in tau clearance from the brain interstitium, our results suggest that regional disruption of AQP4 polarity following TBI may reduce the clearance of the toxic interstitial solutes such as p-tau and lead to changes in dendritic spine density and morphology. This may explain why TBI patients are more vulnerable to cognitive dysfunction.
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Affiliation(s)
- Zi-Ai Zhao
- Molecular Biology Center, State Key Laboratory of Trauma, Burn, and Combined Injury, Research Institute of Surgery and Daping Hospital, Third Military Medical University, Chongqing, 400042, China
| | - Ping Li
- Molecular Biology Center, State Key Laboratory of Trauma, Burn, and Combined Injury, Research Institute of Surgery and Daping Hospital, Third Military Medical University, Chongqing, 400042, China
| | - Shi-Yang Ye
- Molecular Biology Center, State Key Laboratory of Trauma, Burn, and Combined Injury, Research Institute of Surgery and Daping Hospital, Third Military Medical University, Chongqing, 400042, China
| | - Ya-Lei Ning
- Molecular Biology Center, State Key Laboratory of Trauma, Burn, and Combined Injury, Research Institute of Surgery and Daping Hospital, Third Military Medical University, Chongqing, 400042, China
| | - Hao Wang
- Department of Neurosurgery, Research Institute of Surgery and Daping Hospital, Third Military Medical University, Chongqing, 400042, China
| | - Yan Peng
- Molecular Biology Center, State Key Laboratory of Trauma, Burn, and Combined Injury, Research Institute of Surgery and Daping Hospital, Third Military Medical University, Chongqing, 400042, China
| | - Nan Yang
- Molecular Biology Center, State Key Laboratory of Trauma, Burn, and Combined Injury, Research Institute of Surgery and Daping Hospital, Third Military Medical University, Chongqing, 400042, China
| | - Yan Zhao
- Molecular Biology Center, State Key Laboratory of Trauma, Burn, and Combined Injury, Research Institute of Surgery and Daping Hospital, Third Military Medical University, Chongqing, 400042, China
| | - Zhuo-Hang Zhang
- Molecular Biology Center, State Key Laboratory of Trauma, Burn, and Combined Injury, Research Institute of Surgery and Daping Hospital, Third Military Medical University, Chongqing, 400042, China
| | - Jiang-Fan Chen
- Department of Neurology and Pharmacology, Boston University School of Medicine, Boston, MA, 02118, USA
| | - Yuan-Guo Zhou
- Molecular Biology Center, State Key Laboratory of Trauma, Burn, and Combined Injury, Research Institute of Surgery and Daping Hospital, Third Military Medical University, Chongqing, 400042, China.
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21
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Tomita Y, Dorward H, Yool AJ, Smith E, Townsend AR, Price TJ, Hardingham JE. Role of Aquaporin 1 Signalling in Cancer Development and Progression. Int J Mol Sci 2017; 18:ijms18020299. [PMID: 28146084 PMCID: PMC5343835 DOI: 10.3390/ijms18020299] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 01/19/2017] [Accepted: 01/23/2017] [Indexed: 02/07/2023] Open
Abstract
Cancer is a major health burden worldwide. Despite the advances in our understanding of its pathogenesis and continued improvement in cancer management and outcomes, there remains a strong clinical demand for more accurate and reliable biomarkers of metastatic progression and novel therapeutic targets to abrogate angiogenesis and tumour progression. Aquaporin 1 (AQP1) is a small hydrophobic integral transmembrane protein with a predominant role in trans-cellular water transport. Recently, over-expression of AQP1 has been associated with many types of cancer as a distinctive clinical prognostic factor. This has prompted researchers to evaluate the link between AQP1 and cancer biological functions. Available literature implicates the role of AQP1 in tumour cell migration, invasion and angiogenesis. This article reviews the current understanding of AQP1-facilitated tumour development and progression with a focus on regulatory mechanisms and downstream signalling pathways.
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Affiliation(s)
- Yoko Tomita
- Molecular Oncology, Basil Hetzel Institute, The Queen Elizabeth Hospital & Discipline of Physiology, School of Medicine, University of Adelaide, Adelaide, SA 5000, Australia.
| | - Hilary Dorward
- Molecular Oncology, Basil Hetzel Institute, The Queen Elizabeth Hospital, Woodville South, SA 5011, Australia.
| | - Andrea J Yool
- Discipline of Physiology, School of Medicine, University of Adelaide, Adelaide, SA 5000, Australia.
| | - Eric Smith
- Molecular Oncology, Basil Hetzel Institute, The Queen Elizabeth Hospital, Woodville South, SA 5011, Australia.
| | - Amanda R Townsend
- Medical Oncology, The Queen Elizabeth Hospital & School of Medicine, University of Adelaide, Adelaide, SA 5000, Australia.
| | - Timothy J Price
- Medical Oncology, The Queen Elizabeth Hospital & School of Medicine, University of Adelaide, Adelaide, SA 5000, Australia.
| | - Jennifer E Hardingham
- Molecular Oncology, Basil Hetzel Institute, The Queen Elizabeth Hospital & Discipline of Physiology, School of Medicine, University of Adelaide, Adelaide, SA 5000, Australia.
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22
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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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23
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Hansen JS, Krintel C, Hernebring M, Haataja TJK, de Marè S, Wasserstrom S, Kosinska-Eriksson U, Palmgren M, Holm C, Stenkula KG, Jones HA, Lindkvist-Petersson K. Perilipin 1 binds to aquaporin 7 in human adipocytes and controls its mobility via protein kinase A mediated phosphorylation. Metabolism 2016; 65:1731-1742. [PMID: 27832861 DOI: 10.1016/j.metabol.2016.09.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 09/09/2016] [Accepted: 09/12/2016] [Indexed: 11/23/2022]
Abstract
Accumulating evidence suggests that dysregulated glycerol metabolism contributes to the pathophysiology of obesity and type 2 diabetes. Glycerol efflux from adipocytes is regulated by the aquaglyceroporin AQP7, which is translocated upon hormone stimulation. Here, we propose a molecular mechanism where the AQP7 mobility in adipocytes is dependent on perilipin 1 and protein kinase A. Biochemical analyses combined with ex vivo studies in human primary adipocytes, demonstrate that perilipin 1 binds to AQP7, and that catecholamine activated protein kinase A phosphorylates the N-terminus of AQP7, thereby reducing complex formation. Together, these findings are indicative of how glycerol release is controlled in adipocytes, and may pave the way for the future design of drugs against human metabolic pathologies.
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Affiliation(s)
- Jesper S Hansen
- Department of Experimental Medical Science, Lund University, BMC, 221 84, Lund, Sweden
| | - Christian Krintel
- Department of Experimental Medical Science, Lund University, BMC, 221 84, Lund, Sweden
| | - Malin Hernebring
- Department of Experimental Medical Science, Lund University, BMC, 221 84, Lund, Sweden
| | - Tatu J K Haataja
- Department of Experimental Medical Science, Lund University, BMC, 221 84, Lund, Sweden
| | - Sofia de Marè
- Department of Experimental Medical Science, Lund University, BMC, 221 84, Lund, Sweden
| | - Sebastian Wasserstrom
- Department of Experimental Medical Science, Lund University, BMC, 221 84, Lund, Sweden
| | | | - Madelene Palmgren
- Department of Chemistry and Molecular Biology, University of Gothenburg, 405 30, Gothenburg, Sweden
| | - Cecilia Holm
- Department of Experimental Medical Science, Lund University, BMC, 221 84, Lund, Sweden
| | - Karin G Stenkula
- Department of Experimental Medical Science, Lund University, BMC, 221 84, Lund, Sweden
| | - Helena A Jones
- Department of Experimental Medical Science, Lund University, BMC, 221 84, Lund, Sweden
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Astrocyte Aquaporin Dynamics in Health and Disease. Int J Mol Sci 2016; 17:ijms17071121. [PMID: 27420057 PMCID: PMC4964496 DOI: 10.3390/ijms17071121] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 07/07/2016] [Accepted: 07/07/2016] [Indexed: 02/01/2023] Open
Abstract
The family of aquaporins (AQPs), membrane water channels, consists of diverse types of proteins that are mainly permeable to water; some are also permeable to small solutes, such as glycerol and urea. They have been identified in a wide range of organisms, from microbes to vertebrates and plants, and are expressed in various tissues. Here, we focus on AQP types and their isoforms in astrocytes, a major glial cell type in the central nervous system (CNS). Astrocytes have anatomical contact with the microvasculature, pia, and neurons. Of the many roles that astrocytes have in the CNS, they are key in maintaining water homeostasis. The processes involved in this regulation have been investigated intensively, in particular regulation of the permeability and expression patterns of different AQP types in astrocytes. Three aquaporin types have been described in astrocytes: aquaporins AQP1 and AQP4 and aquaglyceroporin AQP9. The aim here is to review their isoforms, subcellular localization, permeability regulation, and expression patterns in the CNS. In the human CNS, AQP4 is expressed in normal physiological and pathological conditions, but astrocytic expression of AQP1 and AQP9 is mainly associated with a pathological state.
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Plasma Membrane Abundance of Human Aquaporin 5 Is Dynamically Regulated by Multiple Pathways. PLoS One 2015; 10:e0143027. [PMID: 26569106 PMCID: PMC4646687 DOI: 10.1371/journal.pone.0143027] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 10/29/2015] [Indexed: 12/21/2022] Open
Abstract
Aquaporin membrane protein channels mediate cellular water flow. Human aquaporin 5 (AQP5) is highly expressed in the respiratory system and secretory glands where it facilitates the osmotically-driven generation of pulmonary secretions, saliva, sweat and tears. Dysfunctional trafficking of AQP5 has been implicated in several human disease states, including Sjögren's syndrome, bronchitis and cystic fibrosis. In order to investigate how the plasma membrane expression levels of AQP5 are regulated, we studied real-time translocation of GFP-tagged AQP5 in HEK293 cells. We show that AQP5 plasma membrane abundance in transfected HEK293 cells is rapidly and reversibly regulated by at least three independent mechanisms involving phosphorylation at Ser156, protein kinase A activity and extracellular tonicity. The crystal structure of a Ser156 phosphomimetic mutant indicates that its involvement in regulating AQP5 membrane abundance is not mediated by a conformational change of the carboxy-terminus. We suggest that together these pathways regulate cellular water flow.
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26
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Huang H, Liao D, Liang L, Song L, Zhao W. Genistein inhibits rotavirus replication and upregulates AQP4 expression in rotavirus-infected Caco-2 cells. Arch Virol 2015; 160:1421-33. [PMID: 25877820 DOI: 10.1007/s00705-015-2404-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 03/19/2015] [Indexed: 11/29/2022]
Abstract
Rotavirus (RV) is the primary cause of severe dehydrating gastroenteritis and acute diarrheal disease in infants and young children. Previous studies have revealed that genistein can inhibit the infectivity of enveloped or nonenveloped viruses. Although the biological properties of genistein are well studied, the mechanisms of action underlying their anti-rotavirus properties have not been fully elucidated. Here, we report that genistein significantly inhibits RV-Wa replication in vitro by repressing viral RNA transcripts, and possibly viral protein synthesis. Interestingly, we also found that aquaporin 4 (AQP4) mRNA and protein expression, which was downregulated in RV-infected Caco-2 cells, can be upregulated by genistein in a time- and dose-dependent manner. Further experiments confirmed that genistein triggers CREB phosphorylation through PKA activation and subsequently promotes AQP4 gene transcription. These findings suggest that the pathophysiological mechanism of RV infection involves decreased expression of AQP4 and that genistein may be a useful candidate for developing a new anti-RV strategy by inhibiting rotavirus replication and upregulating AQP4 expression via the cAMP/PKA/CREB signaling pathway. Further studies on the effect of genistein on RV-induced diarrhea are warranted.
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Affiliation(s)
- Haohai Huang
- School of Pharmacy, Guangdong Medical College, No. 1, Xincheng Road of Songshan Lake Science and Technology Industry Park, Dongguan, 523808, Guangdong, China
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Herak-Kramberger CM, Breljak D, Ljubojević M, Matokanović M, Lovrić M, Rogić D, Brzica H, Vrhovac I, Karaica D, Micek V, Dupor JI, Brown D, Sabolić I. Sex-dependent expression of water channel AQP1 along the rat nephron. Am J Physiol Renal Physiol 2015; 308:F809-21. [PMID: 25656365 DOI: 10.1152/ajprenal.00368.2014] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 02/03/2015] [Indexed: 11/22/2022] Open
Abstract
In the mammalian kidney, nonglycosylated and glycosylated forms of aquaporin protein 1 (AQP1) coexist in the luminal and basolateral plasma membranes of proximal tubule and descending thin limb. Factors that influence AQP1 expression in (patho)physiological conditions are poorly known. Thus far, only angiotensin II and hypertonicity were found to upregulate AQP1 expression in rat proximal tubule in vivo and in vitro (Bouley R, Palomino Z, Tang SS, Nunes P, Kobori H, Lu HA, Shum WW, Sabolic I, Brown D, Ingelfinger JR, Jung FF. Am J Physiol Renal Physiol 297: F1575-F1586, 2009), a phenomenon that may be relevant for higher blood pressure observed in men and male experimental animals. Here we investigated the sex-dependent AQP1 protein and mRNA expression in the rat kidney by immunochemical methods and qRT-PCR in tissue samples from prepubertal and intact gonadectomized animals and sex hormone-treated gonadectomized adult male and female animals. In adult rats, the overall renal AQP1 protein and mRNA expression was ∼80% and ∼40% higher, respectively, in males than in females, downregulated by gonadectomy in both sexes and upregulated strongly by testosterone and moderately by progesterone treatment; estradiol treatment had no effect. In prepubertal rats, the AQP1 protein expression was low compared with adults and slightly higher in females, whereas the AQP1 mRNA expression was low and similar in both sexes. The observed differences in AQP1 protein expression in various experiments mainly reflect changes in the glycosylated form. The male-dominant expression of renal AQP1 in rats, which develops after puberty largely in the glycosylated form of the protein, may contribute to enhanced fluid reabsorption following the androgen- or progesterone-stimulated activities of sodium-reabsorptive mechanisms in proximal tubules.
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Affiliation(s)
| | - Davorka Breljak
- Molecular Toxicology, Institute for Medical Research and Occupational Health, Zagreb, Croatia
| | - Marija Ljubojević
- Molecular Toxicology, Institute for Medical Research and Occupational Health, Zagreb, Croatia
| | - Mirela Matokanović
- Molecular Toxicology, Institute for Medical Research and Occupational Health, Zagreb, Croatia
| | - Mila Lovrić
- Clinical Institute of Laboratory Diagnosis, University Hospital Center, Zagreb, Croatia
| | - Dunja Rogić
- Clinical Institute of Laboratory Diagnosis, University Hospital Center, Zagreb, Croatia
| | - Hrvoje Brzica
- Molecular Toxicology, Institute for Medical Research and Occupational Health, Zagreb, Croatia
| | - Ivana Vrhovac
- Molecular Toxicology, Institute for Medical Research and Occupational Health, Zagreb, Croatia
| | - Dean Karaica
- Molecular Toxicology, Institute for Medical Research and Occupational Health, Zagreb, Croatia
| | - Vedran Micek
- Molecular Toxicology, Institute for Medical Research and Occupational Health, Zagreb, Croatia
| | | | - Dennis Brown
- Program in Membrane Biology and Division of Nephrology, Center for Systems Biology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Ivan Sabolić
- Molecular Toxicology, Institute for Medical Research and Occupational Health, Zagreb, Croatia;
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Pohl M, Shan Q, Petsch T, Styp-Rekowska B, Matthey P, Bleich M, Bachmann S, Theilig F. Short-term functional adaptation of aquaporin-1 surface expression in the proximal tubule, a component of glomerulotubular balance. J Am Soc Nephrol 2014; 26:1269-78. [PMID: 25270072 DOI: 10.1681/asn.2014020148] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 07/22/2014] [Indexed: 11/03/2022] Open
Abstract
Transepithelial water flow across the renal proximal tubule is mediated predominantly by aquaporin-1 (AQP1). Along this nephron segment, luminal delivery and transepithelial reabsorption are directly coupled, a phenomenon called glomerulotubular balance. We hypothesized that the surface expression of AQP1 is regulated by fluid shear stress, contributing to this effect. Consistent with this finding, we found that the abundance of AQP1 in brush border apical and basolateral membranes was augmented >2-fold by increasing luminal perfusion rates in isolated, microperfused proximal tubules for 15 minutes. Mouse kidneys with diminished endocytosis caused by a conditional deletion of megalin or the chloride channel ClC-5 had constitutively enhanced AQP1 abundance in the proximal tubule brush border membrane. In AQP1-transfected, cultured proximal tubule cells, fluid shear stress or the addition of cyclic nucleotides enhanced AQP1 surface expression and concomitantly diminished its ubiquitination. These effects were also associated with an elevated osmotic water permeability. In sum, we have shown that luminal surface expression of AQP1 in the proximal tubule brush border membrane is regulated in response to flow. Cellular trafficking, endocytosis, an intact endosomal compartment, and controlled protein stability are the likely prerequisites for AQP1 activation by enhanced tubular fluid shear stress, serving to maintain glomerulotubular balance.
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Affiliation(s)
- Marcus Pohl
- Institute of Anatomy, Charité Universitätsmedizin, Berlin, Germany
| | - Qixian Shan
- Institute of Physiology, Kiel University, Kiel, Germany
| | - Thomas Petsch
- Institute of Anatomy, Charité Universitätsmedizin, Berlin, Germany
| | | | - Patricia Matthey
- Institute of Anatomy, Department of Medicine, University of Fribourg, Fribourg, Switzerland
| | - Markus Bleich
- Institute of Physiology, Kiel University, Kiel, Germany
| | | | - Franziska Theilig
- Institute of Anatomy, Charité Universitätsmedizin, Berlin, Germany; Institute of Anatomy, Department of Medicine, University of Fribourg, Fribourg, Switzerland
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Day RE, Kitchen P, Owen DS, Bland C, Marshall L, Conner AC, Bill RM, Conner MT. Human aquaporins: regulators of transcellular water flow. Biochim Biophys Acta Gen Subj 2013; 1840:1492-506. [PMID: 24090884 DOI: 10.1016/j.bbagen.2013.09.033] [Citation(s) in RCA: 187] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 09/19/2013] [Accepted: 09/23/2013] [Indexed: 02/06/2023]
Abstract
BACKGROUND Emerging evidence supports the view that (AQP) aquaporin water channels are regulators of transcellular water flow. Consistent with their expression in most tissues, AQPs are associated with diverse physiological and pathophysiological processes. SCOPE OF REVIEW AQP knockout studies suggest that the regulatory role of AQPs, rather than their action as passive channels, is their critical function. Transport through all AQPs occurs by a common passive mechanism, but their regulation and cellular distribution varies significantly depending on cell and tissue type; the role of AQPs in cell volume regulation (CVR) is particularly notable. This review examines the regulatory role of AQPs in transcellular water flow, especially in CVR. We focus on key systems of the human body, encompassing processes as diverse as urine concentration in the kidney to clearance of brain oedema. MAJOR CONCLUSIONS AQPs are crucial for the regulation of water homeostasis, providing selective pores for the rapid movement of water across diverse cell membranes and playing regulatory roles in CVR. Gating mechanisms have been proposed for human AQPs, but have only been reported for plant and microbial AQPs. Consequently, it is likely that the distribution and abundance of AQPs in a particular membrane is the determinant of membrane water permeability and a regulator of transcellular water flow. GENERAL SIGNIFICANCE Elucidating the mechanisms that regulate transcellular water flow will improve our understanding of the human body in health and disease. The central role of specific AQPs in regulating water homeostasis will provide routes to a range of novel therapies. This article is part of a Special Issue entitled Aquaporins.
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Affiliation(s)
- Rebecca E Day
- Biomedical Research Centre, Sheffield Hallam University, Howard Street, Sheffield S1 1WB, UK
| | - Philip Kitchen
- Molecular Organisation and Assembly in Cells Doctoral Training Centre, University of Warwick, Coventry CV4 7AL, UK
| | - David S Owen
- Biomedical Research Centre, Sheffield Hallam University, Howard Street, Sheffield S1 1WB, UK
| | - Charlotte Bland
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Lindsay Marshall
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Alex C Conner
- School of Clinical and Experimental Medicine, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
| | - Roslyn M Bill
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK.
| | - Matthew T Conner
- Biomedical Research Centre, Sheffield Hallam University, Howard Street, Sheffield S1 1WB, UK.
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30
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Zhou S, Sun X, Liu L, Wang X, Liu K. Increased expression of aquaporin-1 in the anterior temporal neocortex of patients with intractable epilepsy. Neurol Res 2013; 30:400-5. [DOI: 10.1179/174313208x300431] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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31
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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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Chung JS, Maurer L, Bratcher M, Pitula JS, Ogburn MB. Cloning of aquaporin-1 of the blue crab, Callinectes sapidus: its expression during the larval development in hyposalinity. AQUATIC BIOSYSTEMS 2012; 8:21. [PMID: 22943628 PMCID: PMC3489796 DOI: 10.1186/2046-9063-8-21] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Accepted: 07/25/2012] [Indexed: 06/01/2023]
Abstract
BACKGROUND Ontogenetic variation in salinity adaptation has been noted for the blue crab, Callinectes sapidus, which uses the export strategy for larval development: females migrate from the estuaries to the coast to spawn, larvae develop in the ocean, and postlarvae (megalopae) colonize estuarine areas. We hypothesized that C. sapidus larvae may be stenohaline and have limited osmoregulatory capacity which compromises their ability to survive in lower salinity waters. We tested this hypothesis using hatchery-raised larvae that were traceable to specific life stages. In addition, we aimed to understand the possible involvement of AQP-1 in salinity adaptation during larval development and during exposure to hyposalinity. RESULTS A full-length cDNA sequence of aquaporin (GenBank JQ970426) was isolated from the hypodermis of the blue crab, C. sapidus, using PCR with degenerate primers and 5' and 3' RACE. The open reading frame of CasAQP-1 consists of 238 amino acids containing six helical structures and two NPA motifs for the water pore. The expression pattern of CasAQP-1 was ubiquitous in cDNAs from all tissues examined, although higher in the hepatopancreas, thoracic ganglia, abdominal muscle, and hypodermis and lower in the antennal gland, heart, hemocytes, ovary, eyestalk, brain, hindgut, Y-organs, and gill. Callinectes larvae differed in their capacity to molt in hyposalinity, as those at earlier stages from Zoea (Z) 1 to Z4 had lower molting rates than those from Z5 onwards, as compared to controls kept in 30 ppt water. No difference was found in the survival of larvae held at 15 and 30 ppt. CasAQP-1 expression differed with ontogeny during larval development, with significantly higher expression at Z1-2, compared to other larval stages. The exposure to 15 ppt affected larval-stage dependent CasAQP-1 expression which was significantly higher in Z2- 6 stages than the other larval stages. CONCLUSIONS We report the ontogenetic variation in CasAQP-1 expression during the larval development of C. sapidus and the induction of its expression at early larval stages in the exposure of hyposalinity. However, it remains to be determined if the increase in CasAQP-1 expression at later larval stages may have a role in adaptation to hyposalinity.
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Affiliation(s)
- J Sook Chung
- Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science, 701 East Pratt Street, Columbus Center, Suite 236, Baltimore, MD, USA
| | - Leah Maurer
- Department of Environmental Science, University of Maryland Baltimore County, Baltimore, MD, USA
| | - Meagan Bratcher
- Department of Natural Sciences, University of Maryland Eastern Shore, Princess Anne, MD, USA
| | - Joseph S Pitula
- Department of Natural Sciences, University of Maryland Eastern Shore, Princess Anne, MD, USA
| | - Matthew B Ogburn
- Department of Natural Sciences, Savannah State University, Savannah, GA, USA
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Jablonski EM, Hughes FM. The potential role of caveolin-1 in inhibition of aquaporins during the AVD. Biol Cell 2012; 98:33-42. [PMID: 16354160 DOI: 10.1042/bc20040131] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND INFORMATION During apoptosis, the first morphological change is a distinct cell shrinkage known as the AVD (apoptotic volume decrease). This event is driven by a loss of intracellular K(+), which creates an osmotic gradient, drawing water out of the cell through AQPs (aquaporins). Loss of water in balance with K(+) would create a shrunken cell with an equivalent intracellular concentration of K(+) ([K(+)](i) = 140 mM). However, we have previously shown that the [K(+)](i) of the shrunken apoptotic cell is 35 mM, and this level is absolutely essential for the activation of apoptotic enzymes. We have recently found that AQPs are inactivated following the AVD, so that continued loss of K(+) will reduce the intracellular concentration to this critical level. Using thymocytes, we have investigated the expression profile and regulation of the AQP family members. RESULTS In the present study, we have found that AQP1, AQP8 and AQP9 are present in non-apoptotic thymocytes and localized primarily to the plasma membrane. Expression and localization did not change when these cells were induced to undergo apoptosis by growth factor withdrawal for 24 h. To explore other possible mechanisms by which these water channels are inactivated, we investigated their association with CAV-1 (caveolin-1), binding to which is known to inactivate a variety of proteins. We found that CAV-1 is present in thymocytes and that this protein co-localizes with a portion of AQP1 in normal (non-apoptotic) thymocytes. However, thymocytes induced to undergo apoptosis greatly increase their AQP1/CAV-1 association. CONCLUSIONS Taken together, these results indicate that AQPs are localized to the plasma membrane of shrunken apoptotic thymocytes where increased binding to CAV-1 potentially inactivates them. AQP inactivation, coupled with continued K(+) efflux, then allows the [K(+)](i) to decrease to levels conducive for the activation of downstream apoptotic enzymes and the completion of the apoptotic cascade.
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Carmosino M, Procino G, Tamma G, Mannucci R, Svelto M, Valenti G. Trafficking and phosphorylation dynamics of AQP4 in histamine-treated human gastric cells. Biol Cell 2012; 99:25-36. [PMID: 16895520 DOI: 10.1042/bc20060068] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND INFORMATION AQP4 (aquaporin 4) internalization and a concomitant decrease in the osmotic water permeability coefficient (Pf) after histamine exposure has been reported in AQP4-transfected gastric HGT1 cells. RESULTS In the present study we report that AQP4 internalization is followed by an increase in AQP4 phosphorylation. Histamine treatment for 30 min resulted in an approx. 10-fold increase in AQP4 phosphorylation that was inhibited by 1 microM H89, a specific PKA (protein kinase A) inhibitor, but not by PKC (protein kinase C) and CK2 inhibitors. Moreover, measurement of PKA activity after 30 min of histamine treatment showed that PKA activity was approx. 3-fold higher compared with basal conditions. AQP4 phosphorylation was prevented in cells treated with histamine for 30 min after pre-incubation with PAO (phenylarsine oxide), an inhibitor of protein endocytosis. Using an endo-exocytosis assay we showed that, after histamine washed out, internalized AQP4 recycled back to the cell surface, even in cells in which de novo protein synthesis was inhibited by cycloheximide. CONCLUSIONS Phosphorylation experiments, combined with immunolocalization studies, indicated that AQP4 phosphorylation is mediated by PKA and occurs subsequently to its internalization in late endosomes. We suggest that phosphorylation might be a mechanism involved in retaining AQP4 in a vesicle-recycling compartment.
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Affiliation(s)
- Monica Carmosino
- Department of General and Environmental Physiology, University of Bari, Via Amendola 165/A, 70126 Bari, Italy
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Functional and transcriptional induction of aquaporin-1 gene by hypoxia; analysis of promoter and role of Hif-1α. PLoS One 2011; 6:e28385. [PMID: 22174795 PMCID: PMC3233559 DOI: 10.1371/journal.pone.0028385] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 11/07/2011] [Indexed: 01/11/2023] Open
Abstract
Aquaporin-1 (AQP1) is a water channel that is highly expressed in tissues with rapid O2 transport. It has been reported that this protein contributes to gas permeation (CO2, NO and O2) through the plasma membrane. We show that hypoxia increases Aqp1 mRNA and protein levels in tissues, namely mouse brain and lung, and in cultured cells, the 9L glioma cell line. Stopped-flow light-scattering experiments confirmed an increase in the water permeability of 9L cells exposed to hypoxia, supporting the view that hypoxic Aqp1 up-regulation has a functional role. To investigate the molecular mechanisms underlying this regulatory process, transcriptional regulation was studied by transient transfections of mouse endothelial cells with a 1297 bp 5′ proximal Aqp1 promoter-luciferase construct. Incubation in hypoxia produced a dose- and time-dependent induction of luciferase activity that was also obtained after treatments with hypoxia mimetics (DMOG and CoCl2) and by overexpressing stabilized mutated forms of HIF-1α. Single mutations or full deletions of the three putative HIF binding domains present in the Aqp1 promoter partially reduced its responsiveness to hypoxia, and transfection with Hif-1α siRNA decreased the in vitro hypoxia induction of Aqp1 mRNA and protein levels. Our results indicate that HIF-1α participates in the hypoxic induction of AQP1. However, we also demonstrate that the activation of Aqp1 promoter by hypoxia is complex and multifactorial and suggest that besides HIF-1α other transcription factors might contribute to this regulatory process. These data provide a conceptual framework to support future research on the involvement of AQP1 in a range of pathophysiological conditions, including edema, tumor growth, and respiratory diseases.
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36
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Zelenina M. Regulation of brain aquaporins. Neurochem Int 2010; 57:468-88. [DOI: 10.1016/j.neuint.2010.03.022] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 03/21/2010] [Accepted: 03/31/2010] [Indexed: 01/27/2023]
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Törnroth-Horsefield S, Hedfalk K, Fischer G, Lindkvist-Petersson K, Neutze R. Structural insights into eukaryotic aquaporin regulation. FEBS Lett 2010; 584:2580-8. [DOI: 10.1016/j.febslet.2010.04.037] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Accepted: 04/14/2010] [Indexed: 01/24/2023]
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38
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Conner MT, Conner AC, Brown JEP, Bill RM. Membrane Trafficking of Aquaporin 1 Is Mediated by Protein Kinase C via Microtubules and Regulated by Tonicity. Biochemistry 2010; 49:821-3. [DOI: 10.1021/bi902068b] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Matthew T. Conner
- Life and Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, U.K
| | - Alex C. Conner
- Warwick Medical School, Warwick University, Coventry CV4 7AL, U.K
| | - James E. P. Brown
- Life and Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, U.K
| | - Roslyn M. Bill
- Life and Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, U.K
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Abstract
Human aquaporin 5 (HsAQP5) facilitates the transport of water across plasma membranes and has been identified within cells of the stomach, duodenum, pancreas, airways, lungs, salivary glands, sweat glands, eyes, lacrimal glands, and the inner ear. AQP5, like AQP2, is subject to posttranslational regulation by phosphorylation, at which point it is trafficked between intracellular storage compartments and the plasma membrane. Details concerning the molecular mechanism of membrane trafficking are unknown. Here we report the x-ray structure of HsAQP5 to 2.0-A resolution and highlight structural similarities and differences relative to other eukaryotic aquaporins. A lipid occludes the putative central pore, preventing the passage of gas or ions through the center of the tetramer. Multiple consensus phosphorylation sites are observed in the structure and their potential regulatory role is discussed. We postulate that a change in the conformation of the C terminus may arise from the phosphorylation of AQP5 and thereby signal trafficking.
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Magni F, Chinello C, Raimondo F, Mocarelli P, Kienle MG, Pitto M. AQP1 expression analysis in human diseases: implications for proteomic characterization. Expert Rev Proteomics 2008; 5:29-43. [PMID: 18282122 DOI: 10.1586/14789450.5.1.29] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Aquaporin (AQP)1 belongs to a ubiquitous family of water channel proteins characterized by sequence similarity and the presence of two NPA (Asp-Pro-Ala) motifs existing in almost all organs and tissues. Currently, 13 human AQPs are known and they are divided into two subgroups according to their ability to transport only water molecules, such as AQP1, or also glycerol and other small solutes. The genomic, structural and functional aspects of AQP1 are briefly described. An in-depth discussion is devoted to proteomic approaches that are useful for identifying and characterizing AQP1, mainly through electrophoretic techniques combined with different extraction procedures followed by mass spectrometry analysis. Moreover, the relevance of AQP1 in human diseases is also explained. Its role in human tumors and, in particular, those of the kidney (e.g., clear cell renal carcinoma) is discussed.
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Affiliation(s)
- Fulvio Magni
- Department of Experimental Medicine, Faculty of Medicine, Via Cadore 48, 20052 Monza, Italy.
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Chapter 2 Ocular Aquaporins and Aqueous Humor Dynamics. CURRENT TOPICS IN MEMBRANES 2008. [DOI: 10.1016/s1063-5823(08)00402-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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Kim JG, Son YJ, Yun CH, Kim YI, Nam-Goong IS, Park JH, Park SK, Ojeda SR, D'Elia AV, Damante G, Lee BJ. Thyroid transcription factor-1 facilitates cerebrospinal fluid formation by regulating aquaporin-1 synthesis in the brain. J Biol Chem 2007; 282:14923-31. [PMID: 17371871 DOI: 10.1074/jbc.m701411200] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In the brain, aquaporin-1 (AQP-1), a water channel for high osmotic water permeability, is mainly expressed in the apical membrane of the ventricular choroid plexus and regulates formation of cerebrospinal fluid (CSF). Although the physiology of AQP-1 has been the subject of several publications, much less is known about the trans-acting factors involved in the control of AQP-1 gene expression. Here we report that TTF-1, a homeodomain-containing transcriptional regulator, is coexpressed with AQP-1 in the rat brain choroid plexus and enhances AQP-1 gene transcription by binding to conserved core TTF-1-binding motifs in the 5'-flanking region of the AQP-1 gene. Intracerebroventricular administration of an antisense TTF-1 oligodeoxynucleotide significantly decreased AQP-1 synthesis and reduced CSF formation. In addition, blockade of TTF-1 synthesis increased survival of the animals following acute water intoxication-induced brain edema. These results suggest that TTF-1 is physiologically involved in the transcriptional control of AQP-1, which is required for CSF formation.
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Affiliation(s)
- Jae Geun Kim
- Department of Biological Sciences, College of Natural Sciences, University of Ulsan, Ulsan 680-749, South Korea
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Magni F, Sarto C, Ticozzi D, Soldi M, Bosso N, Mocarelli P, Kienle MG. Proteomic knowledge of human aquaporins. Proteomics 2007; 6:5637-49. [PMID: 17044001 DOI: 10.1002/pmic.200600212] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Aquaporins (AQPs) are an ubiquitous family of proteins characterized by sequence similarity and the presence of two NPA (Asp-Pro-Ala) motifs. At present, 13 human AQPs are known and they are divided into two subgroups according to their ability to transport only water molecules (AQP0, AQP1, AQP2, AQP4, AQP5, AQP6, and AQP8), or also glycerol and other small solutes (AQP3, AQP7, AQP9, AQP10, AQP12). The genomic, structural, and functional aspects of this family are briefly described. In particular, proteomic approaches to identify and characterize the most studied AQPs, mainly through SDS-PAGE followed by MS analysis, are discussed. Moreover, the clinical importance of the best studied aquaporin (AQP1) in human diseases is also provided.
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Affiliation(s)
- Fulvio Magni
- Department of Experimental, Environmental Medicine and Medical Biotechnologies, University of Milano-Bicocca, Monza, Italy
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Peng J, Zhang H, Li T, Li Z, Wu Y. Effect of dexamethasone and aquaporin-1 antisense oligonucleotides on the aquaporin-1 expression in cultured human trabecular meshwork cells. ACTA ACUST UNITED AC 2006; 26:137-40. [PMID: 16711029 DOI: 10.1007/bf02828061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The changes in the expression of aquaporin-1 (AQP1) mRNA and protein in cultured human trabecular meshwork (HTM) cells treated with dexamethasone and transfected with antisense oligonucleotides (AS-ODN) were studied, and the implication of AQP1 regulation in corticosteroid-glaucoma and the possibility of AS-ODN inhibiting the AQP1 expression were evaluated. The cultured HTM cells in vitro were treated with different concentrations of dexamethasone and transfected with oligonucleotides for 5 days respectively. Then, total RNA and protein of HTM cells were extracted. The changes of AQP1 mRNA and protein were demonstrated qualitatively and quantitatively by RT-PCR and Western blot. Band intensities were detected by imaging analysis. There was a parallel relationship between the results of RT-PCR and those of Western blot. The expression levels of AQP1 mRNA and protein in dexamethasone-treated groups were increased initially and decreased later as dexamethasone concentration was stepped up. In the 0. 04 microg/mL and 0.4 microg/mL groups, the levels of AQP1 were higher than in control group (0 microg/mL). In the 4 microg/ mL and 40 microg/mL groups, the AQP1 expression levels were lower than in control group. AS-ODN could down-regulate the expression of AQP1 mRNA and protein in a dose-dependent manner. At 5 microg/mL, down-regulation efficiency reached the maximum. There was no statistically significant difference in the expression of AQP1 mRNA and protein between all sense oligonucleotides groups and control group. It was suggested that dexamethasone may induce the changes of the AQP1 expression in HTM cells to be involved in the occurrence of corticosteroid-glaucoma. AS-ODN can down-regulate the AQP1 expression in HTM cells to some extent.
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Affiliation(s)
- Jie Peng
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
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Hedfalk K, Törnroth-Horsefield S, Nyblom M, Johanson U, Kjellbom P, Neutze R. Aquaporin gating. Curr Opin Struct Biol 2006; 16:447-56. [PMID: 16837191 DOI: 10.1016/j.sbi.2006.06.009] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2006] [Revised: 06/02/2006] [Accepted: 06/27/2006] [Indexed: 10/24/2022]
Abstract
An acceleration in the rate at which new aquaporin structures are determined means that structural models are now available for mammalian AQP0, AQP1, AQP2 and AQP4, bacterial GlpF, AqpM and AQPZ, and the plant SoPIP2;1. With an apparent consensus emerging concerning the mechanism of selective water transport and proton extrusion, emphasis has shifted towards the issues of substrate selectivity and the mechanisms of aquaporin regulation. In particular, recently determined structures of plant SoPIP2;1, sheep and bovine AQP0, and Escherichia coli AQPZ provide new insights into the underlying structural mechanisms by which water transport rates are regulated in diverse organisms. From these results, two distinct pictures of 'capping' and 'pinching' have emerged to describe aquaporin gating.
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Affiliation(s)
- Kristina Hedfalk
- Chalmers University of Technology, Department of Chemistry and Bioscience, SE-405 30 Göteborg, Sweden
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Yamaguchi Y, Watanabe T, Hirakata A, Hida T. Localization and ontogeny of aquaporin-1 and -4 expression in iris and ciliary epithelial cells in rats. Cell Tissue Res 2006; 325:101-9. [PMID: 16525835 DOI: 10.1007/s00441-005-0122-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2005] [Accepted: 11/08/2005] [Indexed: 10/24/2022]
Abstract
The precise localization of aquaporin (AQP)1 and AQP4 was studied in iris and ciliary epithelial cells, in both mature and developing rats, to elucidate the molecular mechanisms underlying aqueous humor balance. Anterior segments of eyes dissected from embryonic day (E)13, E15, E18, and E20, postnatal day (P)0, P7, and P14, and postnatal week 8 rats were subjected to immunofluorescence analysis with AQP isoform-specific antibodies. In adult rat eye, AQP1 was localized to the apical and basolateral plasma membranes of iris epithelial cell layers and of anterior ciliary non-pigmented epithelial (NPE) cells. Conversely, AQP4 was localized to the basolateral plasma membrane of NPE cells in ciliary epithelium and the posterior iris. Developmentally, AQP1 was detected as early as E15 in immature iris and ciliary epithelial cells, and expression persisted throughout development up to adulthood. In contrast, AQP4 was first observed at P7 in the developing pars plicata, and the AQP4-positive area gradually spread to cover the entire pars plicata as development proceeded. These findings indicate that both AQP1 and AQP4 contribute to aqueous humor secretion in the rat eye, thereby maintaining proper intraocular pressure. Moreover, AQP appears to play a major role in aqueous humor secretion in early eye development. This study thus provides a basis for understanding the molecular mechanisms of aqueous humor secretion in pathological and physiological conditions.
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Affiliation(s)
- Yasuko Yamaguchi
- Department of Ophthalmology, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo 181-8611, Japan.
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Botto L, Beretta E, Daffara R, Miserocchi G, Palestini P. Biochemical and morphological changes in endothelial cells in response to hypoxic interstitial edema. Respir Res 2006; 7:7. [PMID: 16412226 PMCID: PMC1363731 DOI: 10.1186/1465-9921-7-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2005] [Accepted: 01/13/2006] [Indexed: 11/10/2022] Open
Abstract
Background A correlation between interstial pulmonary matrix disorganization and lung cellular response was recently documented in cardiogenic interstitial edema as changes in the signal-cellular transduction platforms (lipid microdomains: caveoale and lipid rafts). These findings led to hypothesize a specific "sensing" function by lung cells resulting from a perturbation in cell-matrix interaction. We reason that the cell-matrix interaction may differ between the cardiogenic and the hypoxic type of lung edema due to the observed difference in the sequential degradation of matrix proteoglycans (PGs) family. In cardiogenic edema a major fragmentation of high molecular weight PGs of the interfibrillar matrix was found, while in hypoxia the fragmentation process mostly involved the PGs of the basement membrane controlling microvascular permeability. Based on these considerations, we aim to describe potential differences in the lung cellular response to the two types of edema. Methods We analysed the composition of plasma membrane and of lipid microdomains in lung tissue samples from anesthetized rabbits exposed to mild hypoxia (12 % O2 for 3–5 h) causing interstitial lung edema. Lipid analysis was performed by chromatographic techniques, while protein analysis by electrophoresis and Western blotting. Lipid peroxidation was assessed on total plasma membranes by a colorimetric assay (Bioxytech LPO-586, OxisResearch). Plasma membrane fluidity was also assessed by fluorescence. Lipid microdomains were isolated by discontinuous sucrose gradient. We also performed a morphometric analysis on lung cell shape on TEM images from lung tissue specimen. Results After hypoxia, phospholipids content in plasma membranes remained unchanged while the cholesterol/phospholipids ratio increased significantly by about 9% causing a decrease in membrane fluidity. No significant increase in lipid peroxidation was detected. Analysis of lipid microdomains showed a decrease of caveolin-1 and AQP1 (markers of caveolae), and an increase in CD55 (marker of lipid rafts). Morphometry showed a significant decrease in endothelial cell volume, a marked increase in the cell surface/volume ratio and a decrease in caveolar density; epithelial cells did not show morphological changes. Conclusion The biochemical, signaling and morphological changes observed in lung endothelial cell exposed to hypoxia are opposite to those previously described in cardiogenic edema, suggesting a differential cellular response to either type of edema.
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Affiliation(s)
- Laura Botto
- Department of Experimental, Environmental Medicine and Biotechnologies (DIMESAB), University of Milano-Bicocca, Via Cadore 48 20052 Monza, Italy
| | - Egidio Beretta
- Department of Experimental, Environmental Medicine and Biotechnologies (DIMESAB), University of Milano-Bicocca, Via Cadore 48 20052 Monza, Italy
| | - Rossella Daffara
- Department of Experimental, Environmental Medicine and Biotechnologies (DIMESAB), University of Milano-Bicocca, Via Cadore 48 20052 Monza, Italy
| | - Giuseppe Miserocchi
- Department of Experimental, Environmental Medicine and Biotechnologies (DIMESAB), University of Milano-Bicocca, Via Cadore 48 20052 Monza, Italy
| | - Paola Palestini
- Department of Experimental, Environmental Medicine and Biotechnologies (DIMESAB), University of Milano-Bicocca, Via Cadore 48 20052 Monza, Italy
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Buck TM, Eledge J, Skach WR. Evidence for stabilization of aquaporin-2 folding mutants byN-linked glycosylation in endoplasmic reticulum. Am J Physiol Cell Physiol 2004; 287:C1292-9. [PMID: 15253895 DOI: 10.1152/ajpcell.00561.2003] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Aquaporin-2 (AQP2) is the vasopressin-sensitive water channel that regulates water reabsorption in the distal nephron collecting duct. Inherited AQP2 mutations that disrupt folding lead to nephrogenic diabetes insipidus (NDI) by targeting newly synthesized protein for degradation in the endoplasmic reticulum (ER). During synthesis, a subset of wild-type (WT) AQP2 is covalently modified by N-linked glycosylation at residue Asn123. To investigate the affect of glycosylation, we expressed WT AQP2 and four NDI-related mutants in Xenopus laevis oocytes and compared stability of glycosylated and nonglycosylated isoforms. In all constructs, ∼15–20% of newly synthesized AQP2 was covalently modified by N-linked glycosylation. At steady state, however, core glycosylated WT protein was nearly undetectable, whereas all mutants were found predominantly in the glycosylated form (60–70%). Pulse-chase metabolic labeling studies revealed that glycosylated isoforms of mutant AQP2 were significantly more stable than their nonglycosylated counterparts. For nonglycosylated isoforms, the half-life of WT AQP2 was significantly greater (>48 h) than that of mutant AQP2 (T126M 4.1 ± 1.0 h, A147T 4.2 ± 0.60 h, C181W 4.5 ± 0.50 h, R187C 6.8 ± 1.2 h). This is consistent with rapid turnover in the ER as previously reported. In contrast, the half-lives of mutant proteins containing N-linked glycans were similar to WT (∼25 h), indicating that differences in steady-state glycosylation profiles are caused by increased stability of glycosylated mutant proteins. These results suggest that addition of a single N-linked oligosaccharide moiety can partially compensate for ER folding defects induced by disease-related mutations.
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Affiliation(s)
- Teresa M Buck
- Molecular Medicine Division, Department of Medicine, Oregon Health Sciences University, Portland, Oregon 97239, USA
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van der Wouden JM, Maier O, van IJzendoorn SCD, Hoekstra D. Membrane dynamics and the regulation of epithelial cell polarity. INTERNATIONAL REVIEW OF CYTOLOGY 2004; 226:127-64. [PMID: 12921237 DOI: 10.1016/s0074-7696(03)01003-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Plasma membranes of epithelial cells consist of two domains, an apical and a basolateral domain, the surfaces of which differ in composition. The separation of these domains by a tight junction and the fact that specific transport pathways exist for intracellular communication between these domains and distinct intracellular compartments relevant to cell polarity development, have triggered extensive research on issues that focus on how the polarity is generated and maintained. Apart from proper assembly of tight junctions, their potential functioning as landmark for the transport machinery, cell-cell adhesion is obviously instrumental in barrier formation. In recent years, distinct endocytic compartments, defined as subapical compartment or common endosome, were shown to play a prominent role in regulating membrane trafficking to and from polarized membrane domains. Sorting devices remain to be determined but likely include distinct rab proteins, and evidence is accumulating to indicate that signaling events may direct intracellular membrane transport, intimately involved in the biogenesis and maintenance of polarized membrane domains and hence the development of cell polarity.
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Affiliation(s)
- Johanna M van der Wouden
- Department of Membrane Cell Biology, University of Groningen, Antonius Deusinglaan 1, 9713AV Groningen, The Netherlands
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Abstract
Emerging evidence suggests that brain aquaporins (AQP) play important roles for the dynamic regulation of brain water homeostasis and for the regulation of cerebrospinal fluid production. This review deals with the short- and long-term regulation of AQP4 and AQP9, both expressed in astrocytes, and of AQP1, expressed in the choroid plexus. AQP1 and 4 have in other cell types been shown to be regulated by phosphorylation. Phosphorylation affects the gating of AQP4 and the trafficking and insertion into membrane of AQP1. Mercury inhibits the water permeability of AQP1 and AQP9, but not AQP4. The permeability of AQP4 is increased by lead. AQP4 is also regulated by protein-protein interaction. The assembly between AQP4 and syntrophin is required for the proper localization of AQP4 in the astrocyte plasma membrane that faces capillaries. There is evidence from studies on peripheral tissues that steroid hormones regulate the expression of AQP1, AQP4 and AQP9. There is also evidence that the expression of AQP1 can be regulated by ubiquitination, and that osmolality can regulate the expression of AQP1, AQP4 and AQP9. Further insight into the mechanisms by which brain AQPs are regulated will be of utmost clinical importance, since perturbed water flow via brain AQPs has been implicated in many neurological diseases and since, in brain edema, water flow via AQP4 may have a harmful effect.
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Affiliation(s)
- E Gunnarson
- Department of Woman and Child Health, Karolinska Institutet, Stockholm, Sweden
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