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Melnyk S, Bollag WB. Aquaporins in the Cornea. Int J Mol Sci 2024; 25:3748. [PMID: 38612559 PMCID: PMC11011575 DOI: 10.3390/ijms25073748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 03/18/2024] [Accepted: 03/21/2024] [Indexed: 04/14/2024] Open
Abstract
The cornea is an avascular, transparent tissue that allows light to enter the visual system. Accurate vision requires proper maintenance of the cornea's integrity and structure. Due to its exposure to the external environment, the cornea is prone to injury and must undergo proper wound healing to restore vision. Aquaporins (AQPs) are a family of water channels important for passive water transport and, in some family members, the transport of other small molecules; AQPs are expressed in all layers of the cornea. Although their functions as water channels are well established, the direct function of AQPs in the cornea is still being determined and is the focus of this review. AQPs, primarily AQP1, AQP3, and AQP5, have been found to play an important role in maintaining water homeostasis, the corneal structure in relation to proper hydration, and stress responses, as well as wound healing in all layers of the cornea. Due to their many functions in the cornea, the identification of drug targets that modulate the expression of AQPs in the cornea could be beneficial to promote corneal wound healing and restore proper function of this tissue crucial for vision.
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Affiliation(s)
- Samuel Melnyk
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA;
| | - Wendy B. Bollag
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA;
- Charlie Norwood Department of Veterans Affairs Medical Center, Augusta, GA 30904, USA
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2
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Petrova RS, Francis N, Schey KL, Donaldson PJ. Verification of the gene and protein expression of the aquaglyceroporin AQP3 in the mammalian lens. Exp Eye Res 2024; 240:109828. [PMID: 38354944 DOI: 10.1016/j.exer.2024.109828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 02/07/2024] [Accepted: 02/11/2024] [Indexed: 02/16/2024]
Abstract
Transport of water is critical for maintaining the transparency of the avascular lens, and the lens is known to express at least five distinctly different water channels from the Aquaporin (AQP) family of proteins. In this study we report on the identification of a sixth lens AQP, AQP3 an aquaglyceroporin, which in addition to water also transports glycerol and H2O2. AQP3 was identified at the transcript level and protein levels using RT-PCR and Western blotting, respectively, in the mouse, rat, bovine and human lens, showing that its expression is conserved in the mammalian lens. Western blotting showed AQP3 in the lens exists as 25 kDa non-glycosylated and 37 kDa glycosylated monomeric forms in all lens species. To identify the regions in the lens where AQP3 is expressed Western blotting was repeated using epithelial, outer cortical and inner cortical/core fractions isolated from the mouse lens. AQP3 was found in all lens regions, with the highest signal of non-glycosylated AQP3 being found in the epithelium. While in the inner cortex/core region AQP3 signal was not only lower but was predominately from the glycosylated form of AQP3. Immunolabelling of lens sections with AQP3 antibodies confirmed that AQP3 is found in all regions of the adult mouse, and also revealed that the subcellular distribution of AQP3 changes as a function of fiber cell differentiation. In epithelial and peripheral fiber cells of the outer cortex AQP3 labelling was predominately associated with membrane vesicles in the cytoplasm, but in the deeper regions of the lens AQP3 labelling was associated with the plasma membranes of fiber cells located in the inner cortex and core of the lens. To determine how this adult pattern of AQP3 subcellular distribution was established, immunolabelling for AQP3 was performed on embryonic and postnatal lenses. AQP3 expression was first detected on embryonic day (E) 11 in the membranes of primary fiber cells that have started to elongate and fill the lumen of the lens vesicle, while later at E16 the AQP3 labelling in the primary fiber cells had shifted to a predominately cytoplasmic location. In the following postnatal (P) stages of lens growth at P3 and P6, AQP3 labelling remained cytoplasmic across all regions of the lens and it was not until P15 when the pattern of localisation of AQP3 changed to an adult distribution with cytoplasmic labelling detected in the outer cortex and membrane localisation detected in the inner cortex and core of the lens. Comparison of the AQP3 labelling pattern to those obtained previously for AQP0 and AQP5 showed that the subcellular distribution was more similar to AQP5 than AQP0, but there were still significant differences that suggest AQP3 may have unique roles in the maintenance of lens transparency.
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Affiliation(s)
- Rosica S Petrova
- Department of Physiology, School of Medical Sciences, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
| | - Nishanth Francis
- Department of Physiology, School of Medical Sciences, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Kevin L Schey
- Department of Biochemistry, Mass Spectrometry Research Centre, Vanderbilt University, Nashville, 37232, TN, USA
| | - Paul J Donaldson
- Department of Physiology, School of Medical Sciences, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
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Bhend ME, Kempuraj D, Sinha NR, Gupta S, Mohan RR. Role of aquaporins in corneal healing post chemical injury. Exp Eye Res 2023; 228:109390. [PMID: 36696947 PMCID: PMC9975064 DOI: 10.1016/j.exer.2023.109390] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Revised: 12/31/2022] [Accepted: 01/19/2023] [Indexed: 01/23/2023]
Abstract
Aquaporins (AQPs) are transmembrane water channel proteins that regulate the movement of water through the plasma membrane in various tissues including cornea. The cornea is avascular and has specialized microcirculatory mechanisms for homeostasis. AQPs regulate corneal hydration and transparency for normal vision. Currently, there are 13 known isoforms of AQPs that can be subclassified as orthodox AQPs, aquaglyceroporins (AQGPs), or supraquaporins (SAQPs)/unorthodox AQPs. AQPs are implicated in keratocyte function, inflammation, edema, angiogenesis, microvessel proliferation, and the wound-healing process in the cornea. AQPs play an important role in wound healing by facilitating the movement of corneal stromal keratocytes by squeezing through tight stromal matrix and narrow extracellular spaces to the wound site. Deficiency of AQPs can cause reduced concentration of hepatocyte growth factor (HGF) leading to reduced epithelial proliferation, reduced/impaired keratocyte migration, reduced number of keratocytes in the injury site, delayed and abnormal wound healing process. Dysregulated AQPs cause dysfunction in osmolar homeostasis as well as wound healing mechanisms. The cornea is a transparent avascular tissue that constitutes the anterior aspect of the outer covering of the eye and aids in two-thirds of visual light refraction. Being the outermost layer of the eye, the cornea is prone to injury. Of the 13 AQP isoforms, AQP1 is expressed in the stromal keratocytes and endothelial cells, and AQP3 and AQP5 are expressed in epithelial cells in the human cornea. AQPs can facilitate wound healing through aid in cellular migration, proliferation, migration, extracellular matrix (ECM) remodeling and autophagy mechanism. Corneal wound healing post-chemical injury requires an integrative and coordinated activity of the epithelium, stromal keratocytes, endothelium, ECM, and a battery of cytokines and growth factors to restore corneal transparency. If the chemical injury is mild, the cornea will heal with normal clarity, but severe injuries can lead to partial and/or permanent loss of corneal functions. Currently, the role of AQPs in corneal wound healing is poorly understood in the context of chemical injury. This review discusses the current literature and the role of AQPs in corneal homeostasis, wound repair, and potential therapeutic target for acute and chronic corneal injuries.
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Affiliation(s)
- Madeline E Bhend
- Department of Ophthalmology, College of Veterinary Medicine, University of Missouri, Columbia, MO, USA; School of Medicine, University of South Carolina, Columbia, SC, USA; Mason Eye Institute, School of Medicine, University of Missouri, Columbia, MO, USA
| | - Duraisamy Kempuraj
- Department of Ophthalmology, College of Veterinary Medicine, University of Missouri, Columbia, MO, USA; Institute for Neuro-Immune Medicine, Dr. Kiran C. Patel College of Osteopathic Medicine, Nova Southeastern University, Ft. Lauderdale, FL, USA
| | - Nishant R Sinha
- Department of Ophthalmology, College of Veterinary Medicine, University of Missouri, Columbia, MO, USA; Harry S. Truman Memorial Veterans' Hospital, Columbia, MO, USA
| | - Suneel Gupta
- Department of Ophthalmology, College of Veterinary Medicine, University of Missouri, Columbia, MO, USA; Harry S. Truman Memorial Veterans' Hospital, Columbia, MO, USA
| | - Rajiv R Mohan
- Department of Ophthalmology, College of Veterinary Medicine, University of Missouri, Columbia, MO, USA; Harry S. Truman Memorial Veterans' Hospital, Columbia, MO, USA; Mason Eye Institute, School of Medicine, University of Missouri, Columbia, MO, USA.
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Tran TL, Hamann S, Heegaard S. Aquaporins in Eye. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1398:203-209. [PMID: 36717496 DOI: 10.1007/978-981-19-7415-1_14] [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
The major part of the eye consists of water. Continuous movement of water and ions between the ocular compartments and to the systemic circulation is pivotal for many physiological functions in the eye. The movement of water facilitates removal of the many metabolic products of corneal-, ciliary body-, lens-, and retinal metabolism, while maintaining transparency in the optical compartments. Transport across the corneal epithelium and endothelium maintains the corneal transparency. Also, aqueous humor is continuously secreted by the epithelia of the ciliary body and maintains the intraocular pressure. In the retina, water is transported into the vitreous body and across the retinal pigment epithelium to regulate the extracellular environment and the hydration of the retina. Aquaporins are a major contributor in the water transport throughout the eye.
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Affiliation(s)
- Thuy Linh Tran
- Department of Ophthalmology, Rigshospitalet - Glostrup, University of Copenhagen, Copenhagen, Denmark
| | - Steffen Hamann
- Department of Ophthalmology, Rigshospitalet - Glostrup, University of Copenhagen, Copenhagen, Denmark
| | - Steffen Heegaard
- Department of Ophthalmology, Rigshospitalet - Glostrup, University of Copenhagen, Copenhagen, Denmark
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Zhang C, Luo D, Xie H, Yang Q, Liu D, Tang L, Zhang J, Li W, Tian H, Lu L, Sun X, Xu GT, Zhang J. Aquaporin 11 alleviates retinal Müller intracellular edema through water efflux in diabetic retinopathy. Pharmacol Res 2023; 187:106559. [PMID: 36403720 DOI: 10.1016/j.phrs.2022.106559] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 10/17/2022] [Accepted: 11/15/2022] [Indexed: 11/18/2022]
Abstract
Retinal Müller glial dysfunction and intracellular edema are important mechanisms leading to diabetic macular edema (DME). Aquaporin 11 (AQP11) is primarily expressed in Müller glia with unclear functions. This study aims to explore the role of AQP11 in the pathogenesis of intracellular edema of Müller glia in diabetic retinopathy (DR). Here, we found that AQP11 expression, primarily located at the endfeet of Müller glia, was down-regulated with diabetes progression, accompanied by intracellular edema, which was alleviated by intravitreal injection of lentivirus-mediated AQP11 overexpression. Similarly, intracellular edema of hypoxia-treated rat Müller cell line (rMC-1) was aggravated by AQP11 inhibition, while attenuated by AQP11 overexpression, accompanied by enhanced function in glutamate metabolism and reduced cell death. The down-regulation of AQP11 was also verified in the Müller glia from the epiretinal membranes (ERMs) of proliferative DR (PDR) patients. Mechanistically, down-regulation of AQP11 in DR was mediated by the HIF-1α-dependent and independent miRNA-AQP11 axis. Overall, we deciphered the AQP11 down-regulation, mediated by miRNA-AQP11 axis, resulted in Müller drainage dysfunction and subsequent intracellular edema in DR, which was partially reversed by AQP11 overexpression. Our findings propose a novel mechanism for the pathogenesis of DME, thus targeting AQP11 regulation provides a new therapeutic strategy for DME.
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Affiliation(s)
- Chaoyang Zhang
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University School of Medicine, Shanghai, China; National Clinical Research Center for Eye Diseases, Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai, China; Department of Regenerative Medicine, and Department of Pharmacology, Tongji Eye Institute, Tongji University School of Medicine, Shanghai, China
| | - Dawei Luo
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University School of Medicine, Shanghai, China; National Clinical Research Center for Eye Diseases, Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai, China
| | - Hai Xie
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University School of Medicine, Shanghai, China; National Clinical Research Center for Eye Diseases, Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai, China; Department of Regenerative Medicine, and Department of Pharmacology, Tongji Eye Institute, Tongji University School of Medicine, Shanghai, China
| | - Qian Yang
- Department of Regenerative Medicine, and Department of Pharmacology, Tongji Eye Institute, Tongji University School of Medicine, Shanghai, China
| | - Dandan Liu
- Department of Regenerative Medicine, and Department of Pharmacology, Tongji Eye Institute, Tongji University School of Medicine, Shanghai, China
| | - Lei Tang
- Department of Regenerative Medicine, and Department of Pharmacology, Tongji Eye Institute, Tongji University School of Medicine, Shanghai, China
| | - Jingting Zhang
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University School of Medicine, Shanghai, China; National Clinical Research Center for Eye Diseases, Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai, China
| | - Weiye Li
- Department of Regenerative Medicine, and Department of Pharmacology, Tongji Eye Institute, Tongji University School of Medicine, Shanghai, China; Department of Ophthalmology, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Haibin Tian
- Department of Regenerative Medicine, and Department of Pharmacology, Tongji Eye Institute, Tongji University School of Medicine, Shanghai, China
| | - Lixia Lu
- Department of Regenerative Medicine, and Department of Pharmacology, Tongji Eye Institute, Tongji University School of Medicine, Shanghai, China
| | - Xiaodong Sun
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University School of Medicine, Shanghai, China; National Clinical Research Center for Eye Diseases, Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai, China.
| | - Guo-Tong Xu
- Department of Regenerative Medicine, and Department of Pharmacology, Tongji Eye Institute, Tongji University School of Medicine, Shanghai, China.
| | - Jingfa Zhang
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University School of Medicine, Shanghai, China; National Clinical Research Center for Eye Diseases, Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai, China; Department of Regenerative Medicine, and Department of Pharmacology, Tongji Eye Institute, Tongji University School of Medicine, Shanghai, China.
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da Silva IV, Garra S, Calamita G, Soveral G. The Multifaceted Role of Aquaporin-9 in Health and Its Potential as a Clinical Biomarker. Biomolecules 2022; 12:biom12070897. [PMID: 35883453 PMCID: PMC9313442 DOI: 10.3390/biom12070897] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 06/23/2022] [Accepted: 06/25/2022] [Indexed: 12/10/2022] Open
Abstract
Aquaporins (AQPs) are transmembrane channels essential for water, energy, and redox homeostasis, with proven involvement in a variety of pathophysiological conditions such as edema, glaucoma, nephrogenic diabetes insipidus, oxidative stress, sepsis, cancer, and metabolic dysfunctions. The 13 AQPs present in humans are widely distributed in all body districts, drawing cell lineage-specific expression patterns closely related to cell native functions. Compelling evidence indicates that AQPs are proteins with great potential as biomarkers and targets for therapeutic intervention. Aquaporin-9 (AQP9) is the most expressed in the liver, with implications in general metabolic and redox balance due to its aquaglyceroporin and peroxiporin activities, facilitating glycerol and hydrogen peroxide (H2O2) diffusion across membranes. AQP9 is also expressed in other tissues, and their altered expression is described in several human diseases, such as liver injury, inflammation, cancer, infertility, and immune disorders. The present review compiles the current knowledge of AQP9 implication in diseases and highlights its potential as a new biomarker for diagnosis and prognosis in clinical medicine.
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Affiliation(s)
- Inês V. da Silva
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, 1649-003 Lisboa, Portugal;
- Department of Pharmaceutical Sciences and Medicines, Faculty of Pharmacy, Universidade de Lisboa, 1649-003 Lisboa, Portugal
| | - Sabino Garra
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari Aldo Moro, 70125 Bari, Italy;
| | - Giuseppe Calamita
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari Aldo Moro, 70125 Bari, Italy;
- Correspondence: (G.C.); (G.S.)
| | - Graça Soveral
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, 1649-003 Lisboa, Portugal;
- Department of Pharmaceutical Sciences and Medicines, Faculty of Pharmacy, Universidade de Lisboa, 1649-003 Lisboa, Portugal
- Correspondence: (G.C.); (G.S.)
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Chen Y, Chen H, Wang C, Yu J, Tao J, Mao J, Shen L. The Correlation between the Increased Expression of Aquaporins on the Inner Limiting Membrane and the Occurrence of Diabetic Macular Edema. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:7412208. [PMID: 35528520 PMCID: PMC9071982 DOI: 10.1155/2022/7412208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 03/23/2022] [Accepted: 04/01/2022] [Indexed: 11/18/2022]
Abstract
Purpose Diabetic macular edema (DME) is a major cause of vision loss in patients with diabetic retinopathy; this study is aimed at comparing the expression of aquaporins (AQPs) on the inner limiting membranes (ILMs) of various vitreoretinal diseases and investigating the role of aquaporins expressed on the ILMs in mediating the occurrence of DME. Methods The whole-mounted ILM specimens surgically excised from patients with various vitreoretinal diseases (idiopathic macular hole, myopic traction maculopathy, and diabetic retinopathy) were analyzed by immunohistochemistry (IHC). The distribution and morphology of AQP4, AQP7, and AQP11 on the ILMs were correlated with immunohistochemical staining characteristics. Moreover, immunofluorescence of AQP4 was performed on the ILM specimens of the patient in four groups: the control group, negative control group, no DME group, and DME group. The immunofluorescence intensity value of AQP4 was measured using ImageJ. The difference between the four groups and the correction between the immunofluorescence value and central foveal thickness (CFT) were analyzed. Results In IHC sections, the expression of AQP4, AQP7, and AQP11 on ILMs of diabetic retinopathy (DR) with macular edema, respectively, seemed to be more abundant than in the idiopathic macular hole (iMH) and myopic traction maculopathy (MTM). Moreover, markedly higher fluorescence intensity of AQP4 of ILMs was determined in the DME group (51.05 ± 5.67) versus the other three groups (P < 0.001). A marked positive association was identified between the fluorescence intensity of AQP4 and CFT (r = 0.758; P = 0.011). Conclusions AQP4, AQP7, and AQP11 can be expressed on human ILM in vivo. The increased expression of AQPs on the ILMs of DR may be associated with the occurrence of DME. Moreover, the degree of DME may be positively correlated with the expression of AQP4 on the ILMs.
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Affiliation(s)
- Yiqi Chen
- Center for Rehabilitation Medicine, Department of Ophthalmology, Zhejiang Provincial People's Hospital (Affiliated People's Hospital, Hangzhou Medical College), Hangzhou, Zhejiang, China
| | - Huan Chen
- Department of Retina Center, Affiliated Eye Hospital of Wenzhou Medical University, Hangzhou, 310000 Zhejiang Province, China
| | - Chenxi Wang
- Center for Rehabilitation Medicine, Department of Ophthalmology, Zhejiang Provincial People's Hospital (Affiliated People's Hospital, Hangzhou Medical College), Hangzhou, Zhejiang, China
| | - Jiafeng Yu
- Center for Rehabilitation Medicine, Department of Ophthalmology, Zhejiang Provincial People's Hospital (Affiliated People's Hospital, Hangzhou Medical College), Hangzhou, Zhejiang, China
| | - Jiwei Tao
- Department of Retina Center, Affiliated Eye Hospital of Wenzhou Medical University, Hangzhou, 310000 Zhejiang Province, China
| | - Jianbo Mao
- Center for Rehabilitation Medicine, Department of Ophthalmology, Zhejiang Provincial People's Hospital (Affiliated People's Hospital, Hangzhou Medical College), Hangzhou, Zhejiang, China
| | - Lijun Shen
- Center for Rehabilitation Medicine, Department of Ophthalmology, Zhejiang Provincial People's Hospital (Affiliated People's Hospital, Hangzhou Medical College), Hangzhou, Zhejiang, China
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Schey KL, Gletten RB, O’Neale CVT, Wang Z, Petrova RS, Donaldson PJ. Lens Aquaporins in Health and Disease: Location is Everything! Front Physiol 2022; 13:882550. [PMID: 35514349 PMCID: PMC9062079 DOI: 10.3389/fphys.2022.882550] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 03/23/2022] [Indexed: 01/07/2023] Open
Abstract
Cataract and presbyopia are the leading cause of vision loss and impaired vision, respectively, worldwide. Changes in lens biochemistry and physiology with age are responsible for vision impairment, yet the specific molecular changes that underpin such changes are not entirely understood. In order to preserve transparency over decades of life, the lens establishes and maintains a microcirculation system (MCS) that, through spatially localized ion pumps, induces circulation of water and nutrients into (influx) and metabolites out of (outflow and efflux) the lens. Aquaporins (AQPs) are predicted to play important roles in the establishment and maintenance of local and global water flow throughout the lens. This review discusses the structure and function of lens AQPs and, importantly, their spatial localization that is likely key to proper water flow through the MCS. Moreover, age-related changes are detailed and their predicted effects on the MCS are discussed leading to an updated MCS model. Lastly, the potential therapeutic targeting of AQPs for prevention or treatment of cataract and presbyopia is discussed.
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Affiliation(s)
- Kevin L. Schey
- Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, TN, United States,*Correspondence: Kevin L. Schey,
| | - Romell B. Gletten
- Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, TN, United States
| | - Carla V. T. O’Neale
- Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, TN, United States
| | - Zhen Wang
- Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, TN, United States
| | - Rosica S. Petrova
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Paul J. Donaldson
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
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Li Z, Quan Y, Gu S, Jiang JX. Beyond the Channels: Adhesion Functions of Aquaporin 0 and Connexin 50 in Lens Development. Front Cell Dev Biol 2022; 10:866980. [PMID: 35465319 PMCID: PMC9022433 DOI: 10.3389/fcell.2022.866980] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 03/18/2022] [Indexed: 12/04/2022] Open
Abstract
Lens, an avascular tissue involved in light transmission, generates an internal microcirculatory system to promote ion and fluid circulation, thus providing nutrients to internal lens cells and excreting the waste. This unique system makes up for the lack of vasculature and distinctively maintains lens homeostasis and lens fiber cell survival through channels of connexins and other transporters. Aquaporins (AQP) and connexins (Cx) comprise the majority of channels in the lens microcirculation system and are, thus, essential for lens development and transparency. Mutations of AQPs and Cxs result in abnormal channel function and cataract formation. Interestingly, in the last decade or so, increasing evidence has emerged suggesting that in addition to their well-established channel functions, AQP0 and Cx50 play pivotal roles through channel-independent actions in lens development and transparency. Specifically, AQP0 and Cx50 have been shown to have a unique cell adhesion function that mediates lens development and transparency. Precise regulation of cell-matrix and cell-cell adhesion is necessary for cell migration, a critical process during lens development. This review will provide recent advances in basic research of cell adhesion mediated by AQP0 and Cx50.
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Affiliation(s)
- Zhen Li
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Yumeng Quan
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States
| | - Sumin Gu
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States
| | - Jean X. Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States
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Nakazawa M, Ishikawa H, Sakamoto T. Current understanding of the epidemiologic and clinical characteristics of optic neuritis. Jpn J Ophthalmol 2021; 65:439-447. [PMID: 34021411 DOI: 10.1007/s10384-021-00840-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 04/12/2021] [Indexed: 02/07/2023]
Abstract
Optic neuritis is an ocular disorder whose pathogenesis has not been fully determined, although autoimmune mechanisms have been suggested to be involved in its development. In recent years, anti-aquaporin-4 antibody (AQP4-Ab) and anti-myelin oligodendrocyte glycoprotein antibody (MOG-Ab) have been shown to play major roles in the development of optic neuritis. Because these two antibodies target different tissues, optic neuritis can be classified by the type of antibody. AQP4-Ab-positive optic neuritis responds poorly to steroid therapy and has a poor prognosis in terms of visual acuity. On the other hand, MOG-Ab-positive optic neuritis responds favorably to steroid therapy but is likely to recur when the dosage of steroids is reduced or discontinued. We first present the high incidence of idiopathic optic neuritis and discuss these relatively newer disease concepts of AQP4-Ab-positive optic neuritis and MOG-Ab-positive optic neuritis.
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Affiliation(s)
- Masanori Nakazawa
- Department of Ophthalmology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Hitoshi Ishikawa
- Department of Orthoptics and Visual Science, School of Allied Health Sciences, Kitasato University, Kanagawa, Japan
| | - Taiji Sakamoto
- Department of Ophthalmology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
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Azad AK, Raihan T, Ahmed J, Hakim A, Emon TH, Chowdhury PA. Human Aquaporins: Functional Diversity and Potential Roles in Infectious and Non-infectious Diseases. Front Genet 2021; 12:654865. [PMID: 33796134 PMCID: PMC8007926 DOI: 10.3389/fgene.2021.654865] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Accepted: 02/22/2021] [Indexed: 12/11/2022] Open
Abstract
Aquaporins (AQPs) are integral membrane proteins and found in all living organisms from bacteria to human. AQPs mainly involved in the transmembrane diffusion of water as well as various small solutes in a bidirectional manner are widely distributed in various human tissues. Human contains 13 AQPs (AQP0-AQP12) which are divided into three sub-classes namely orthodox aquaporin (AQP0, 1, 2, 4, 5, 6, and 8), aquaglyceroporin (AQP3, 7, 9, and 10) and super or unorthodox aquaporin (AQP11 and 12) based on their pore selectivity. Human AQPs are functionally diverse, which are involved in wide variety of non-infectious diseases including cancer, renal dysfunction, neurological disorder, epilepsy, skin disease, metabolic syndrome, and even cardiac diseases. However, the association of AQPs with infectious diseases has not been fully evaluated. Several studies have unveiled that AQPs can be regulated by microbial and parasitic infections that suggest their involvement in microbial pathogenesis, inflammation-associated responses and AQP-mediated cell water homeostasis. This review mainly aims to shed light on the involvement of AQPs in infectious and non-infectious diseases and potential AQPs-target modulators. Furthermore, AQP structures, tissue-specific distributions and their physiological relevance, functional diversity and regulations have been discussed. Altogether, this review would be useful for further investigation of AQPs as a potential therapeutic target for treatment of infectious as well as non-infectious diseases.
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Affiliation(s)
- Abul Kalam Azad
- Department of Genetic Engineering and Biotechnology, School of Life Sciences, Shahjalal University of Science and Technology, Sylhet, Bangladesh
| | - Topu Raihan
- Department of Genetic Engineering and Biotechnology, School of Life Sciences, Shahjalal University of Science and Technology, Sylhet, Bangladesh
| | - Jahed Ahmed
- Department of Genetic Engineering and Biotechnology, School of Life Sciences, Shahjalal University of Science and Technology, Sylhet, Bangladesh
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Al Hakim
- Department of Genetic Engineering and Biotechnology, School of Life Sciences, Shahjalal University of Science and Technology, Sylhet, Bangladesh
| | - Tanvir Hossain Emon
- Department of Genetic Engineering and Biotechnology, School of Life Sciences, Shahjalal University of Science and Technology, Sylhet, Bangladesh
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Detrimental Effects of UVB on Retinal Pigment Epithelial Cells and Its Role in Age-Related Macular Degeneration. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:1904178. [PMID: 32855763 PMCID: PMC7443017 DOI: 10.1155/2020/1904178] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 07/03/2020] [Accepted: 07/08/2020] [Indexed: 11/25/2022]
Abstract
Retinal pigment epithelial (RPE) cells are an essential part of the human eye because they not only mediate and control the transfer of fluids and solutes but also protect the retina against photooxidative damage and renew photoreceptor cells through phagocytosis. However, their function necessitates cumulative exposure to the sun resulting in UV damage, which may lead to the development of age-related macular degeneration (AMD). Several studies have shown that UVB induces direct DNA damage and oxidative stress in RPE cells by increasing ROS and dysregulating endogenous antioxidants. Activation of different signaling pathways connected to inflammation, cell cycle arrest, and intrinsic apoptosis was reported as well. Besides that, essential functions like phagocytosis, osmoregulation, and water permeability of RPE cells were also affected. Although the melanin within RPE cells can act as a photoprotectant, this photoprotection decreases with age. Nevertheless, the changes in lens epithelium-derived growth factor (LEDGF) and autophagic activity or application of bioactive compounds from natural products can reverse the detrimental effect of UVB. Additionally, in vivo studies on the whole retina demonstrated that UVB irradiation induces gene and protein level dysregulation, indicating cellular stress and aberrations in the chromosome level. Morphological changes like retinal depigmentation and drusen formation were noted as well which is similar to the etiology of AMD, suggesting the connection of UVB damage with AMD. Therefore, future studies, which include mechanism studies via in vitro or in vivo and other potential bioactive compounds, should be pursued for a better understanding of the involvement of UVB in AMD.
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Potential Interplay between Hyperosmolarity and Inflammation on Retinal Pigmented Epithelium in Pathogenesis of Diabetic Retinopathy. Int J Mol Sci 2018; 19:ijms19041056. [PMID: 29614818 PMCID: PMC5979527 DOI: 10.3390/ijms19041056] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 03/21/2018] [Accepted: 03/30/2018] [Indexed: 12/15/2022] Open
Abstract
Diabetic retinopathy is a frequent eyesight threatening complication of type 1 and type 2 diabetes. Under physiological conditions, the inner and the outer blood-retinal barriers protect the retina by regulating ion, protein, and water flux into and out of the retina. During diabetic retinopathy, many factors, including inflammation, contribute to the rupture of the inner and/or the outer blood-retinal barrier. This rupture leads the development of macular edema, a foremost cause of sight loss among diabetic patients. Under these conditions, it has been speculated that retinal pigmented epithelial cells, that constitute the outer blood-retinal barrier, may be subjected to hyperosmolar stress resulting from different mechanisms. Herein, we review the possible origins and consequences of hyperosmolar stress on retinal pigmented epithelial cells during diabetic retinopathy, with a special focus on the intimate interplay between inflammation and hyperosmolar stress, as well as the current and forthcoming new pharmacotherapies for the treatment of such condition.
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Smith DW, Gardiner BS. Estimating outflow facility through pressure dependent pathways of the human eye. PLoS One 2017; 12:e0188769. [PMID: 29261696 PMCID: PMC5738051 DOI: 10.1371/journal.pone.0188769] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Accepted: 11/13/2017] [Indexed: 01/06/2023] Open
Abstract
We develop and test a new theory for pressure dependent outflow from the eye. The theory comprises three main parameters: (i) a constant hydraulic conductivity, (ii) an exponential decay constant and (iii) a no-flow intraocular pressure, from which the total pressure dependent outflow, average outflow facilities and local outflow facilities for the whole eye may be evaluated. We use a new notation to specify precisely the meaning of model parameters and so model outputs. Drawing on a range of published data, we apply the theory to animal eyes, enucleated eyes and in vivo human eyes, and demonstrate how to evaluate model parameters. It is shown that the theory can fit high quality experimental data remarkably well. The new theory predicts that outflow facilities and total pressure dependent outflow for the whole eye are more than twice as large as estimates based on the Goldman equation and fluorometric analysis of anterior aqueous outflow. It appears likely that this discrepancy can be largely explained by pseudofacility and aqueous flow through the retinal pigmented epithelium, while any residual discrepancy may be due to pathological processes in aged eyes. The model predicts that if the hydraulic conductivity is too small, or the exponential decay constant is too large, then intraocular eye pressure may become unstable when subjected to normal circadian changes in aqueous production. The model also predicts relationships between variables that may be helpful when planning future experiments, and the model generates many novel testable hypotheses. With additional research, the analysis described here may find application in the differential diagnosis, prognosis and monitoring of glaucoma.
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Affiliation(s)
- David W. Smith
- Faculty of Engineering and Mathematical Sciences, The University of Western Australia, Perth, Australia
| | - Bruce S. Gardiner
- School of Engineering and Information Technology, Murdoch University, Murdoch, Western Australia, Australia
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Schey KL, Petrova RS, Gletten RB, Donaldson PJ. The Role of Aquaporins in Ocular Lens Homeostasis. Int J Mol Sci 2017; 18:E2693. [PMID: 29231874 PMCID: PMC5751294 DOI: 10.3390/ijms18122693] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 12/08/2017] [Accepted: 12/08/2017] [Indexed: 12/13/2022] Open
Abstract
Abstract: Aquaporins (AQPs), by playing essential roles in the maintenance of ocular lens homeostasis, contribute to the establishment and maintenance of the overall optical properties of the lens over many decades of life. Three aquaporins, AQP0, AQP1 and AQP5, each with distinctly different functional properties, are abundantly and differentially expressed in the different regions of the ocular lens. Furthermore, the diversity of AQP functionality is increased in the absence of protein turnover by age-related modifications to lens AQPs that are proposed to alter AQP function in the different regions of the lens. These regional differences in AQP functionality are proposed to contribute to the generation and directionality of the lens internal microcirculation; a system of circulating ionic and fluid fluxes that delivers nutrients to and removes wastes from the lens faster than could be achieved by passive diffusion alone. In this review, we present how regional differences in lens AQP isoforms potentially contribute to this microcirculation system by highlighting current areas of investigation and emphasizing areas where future work is required.
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Affiliation(s)
- Kevin L Schey
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37240, USA.
| | - Rosica S Petrova
- Department of Physiology, School of Medical Sciences, New Zealand National Eye Centre, University of Auckland, Auckland 1023, New Zealand.
| | - Romell B Gletten
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37240, USA.
| | - Paul J Donaldson
- Department of Physiology, School of Medical Sciences, New Zealand National Eye Centre, University of Auckland, Auckland 1023, New Zealand.
- School of Optometry and Vison Sciences, New Zealand National Eye Centre, University of Auckland, Auckland 1023, New Zealand.
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Shanbagh S, Sasikumar R, Tejwani S, Abilash V, Ghosh A. Wnt and inflammatory pathway mediated differential expression of water channel protein in glaucomatous trabecular meshwork. CANADIAN JOURNAL OF BIOTECHNOLOGY 2017. [DOI: 10.24870/cjb.2017-a129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Abstract
The major part of the eye consists of water . Continuous movement of water and ions between the ocular compartments and to the systemic circulation is pivotal for many physiological functions in the eye. The movement of water facilitates removal of the many metabolic products of corneal-, ciliary body-, lens- and retinal metabolism, while maintaining transparency in the optical compartments. Transport across the corneal epithelium and endothelium maintains the corneal transparency. Also, aqueous humour is continuously secreted by the epithelia of the ciliary body and maintains the intraocular pressure. In the retina, water is transported into the vitreous body and across the retinal pigment epithelium to regulate the extracellular environment and the hydration of the retina. Aquaporins (AQPs ) take part in the water transport throughout the eye.
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Pannicke T, Ivo Chao T, Reisenhofer M, Francke M, Reichenbach A. Comparative electrophysiology of retinal Müller glial cells-A survey on vertebrate species. Glia 2016; 65:533-568. [PMID: 27767232 DOI: 10.1002/glia.23082] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 09/15/2016] [Accepted: 09/28/2016] [Indexed: 12/13/2022]
Abstract
Müller cells are the dominant macroglial cells in the retina of all vertebrates. They fulfill a variety of functions important for retinal physiology, among them spatial buffering of K+ ions and uptake of glutamate and other neurotransmitters. To this end, Müller cells express inwardly rectifying K+ channels and electrogenic glutamate transporters. Moreover, a lot of voltage- and ligand-gated ion channels, aquaporin water channels, and electrogenic transporters are expressed in Müller cells, some of them in a species-specific manner. For example, voltage-dependent Na+ channels are found exclusively in some but not all mammalian species. Whereas a lot of data exist from amphibians and mammals, the results from other vertebrates are sparse. It is the aim of this review to present a survey on Müller cell electrophysiology covering all classes of vertebrates. The focus is on functional studies, mainly performed using the whole-cell patch-clamp technique. However, data about the expression of membrane channels and transporters from immunohistochemistry are also included. Possible functional roles of membrane channels and transporters are discussed. Obviously, electrophysiological properties involved in the main functions of Müller cells developed early in vertebrate evolution. GLIA 2017;65:533-568.
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Affiliation(s)
- Thomas Pannicke
- Paul-Flechsig-Institut für Hirnforschung, Abteilung Pathophysiologie der Neuroglia, Universität Leipzig, Germany
| | - T Ivo Chao
- Institute of Anatomy and Cell Biology, Medical School Göttingen, Germany
| | - Miriam Reisenhofer
- Department of Chemistry, University of Zürich, Switzerland
- Department of Ophthalmology, Inselspital, Bern University Hospital, University of Bern, Switzerland
| | - Mike Francke
- Paul-Flechsig-Institut für Hirnforschung, Abteilung Pathophysiologie der Neuroglia, Universität Leipzig, Germany
- Sächsischer Inkubator für klinische Translation (SIKT), Universität Leipzig, Germany
| | - Andreas Reichenbach
- Paul-Flechsig-Institut für Hirnforschung, Abteilung Pathophysiologie der Neuroglia, Universität Leipzig, Germany
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Murthy KR, Dammalli M, Pinto SM, Murthy KB, Nirujogi RS, Madugundu AK, Dey G, Subbannayya Y, Mishra UK, Nair B, Gowda H, Prasad TK. A Comprehensive Proteomics Analysis of the Human Iris Tissue: Ready to Embrace Postgenomics Precision Medicine in Ophthalmology? OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2016; 20:510-9. [DOI: 10.1089/omi.2016.0100] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Krishna R. Murthy
- Institute of Bioinformatics, International Tech Park, Bangalore, India
- Amrita School of Biotechnology, Amrita VishwaVidyapeetham, Kollam, India
- Vittala International Institute of Ophthalmology, Bangalore, India
| | - Manjunath Dammalli
- Institute of Bioinformatics, International Tech Park, Bangalore, India
- Department of Biotechnology, Siddaganga Institute of Technology, Tumkur, India
| | - Sneha M. Pinto
- Institute of Bioinformatics, International Tech Park, Bangalore, India
- YU-IOB Center for Systems Biology and Molecular Medicine, Yenepoya University, Mangalore, India
| | | | - Raja Sekhar Nirujogi
- Institute of Bioinformatics, International Tech Park, Bangalore, India
- Centre for Bioinformatics, School of Life Sciences, Pondicherry University, Puducherry, India
| | - Anil K. Madugundu
- Institute of Bioinformatics, International Tech Park, Bangalore, India
- Centre for Bioinformatics, School of Life Sciences, Pondicherry University, Puducherry, India
| | - Gourav Dey
- Institute of Bioinformatics, International Tech Park, Bangalore, India
- Manipal University, Manipal, India
| | - Yashwanth Subbannayya
- Institute of Bioinformatics, International Tech Park, Bangalore, India
- YU-IOB Center for Systems Biology and Molecular Medicine, Yenepoya University, Mangalore, India
| | | | - Bipin Nair
- Amrita School of Biotechnology, Amrita VishwaVidyapeetham, Kollam, India
| | - Harsha Gowda
- Institute of Bioinformatics, International Tech Park, Bangalore, India
| | - T.S. Keshava Prasad
- Institute of Bioinformatics, International Tech Park, Bangalore, India
- YU-IOB Center for Systems Biology and Molecular Medicine, Yenepoya University, Mangalore, India
- NIMHANS-IOB Bioinformatics and Proteomics Laboratory, Neurobiology Research Centre, National Institute of Mental Health and Neurosciences, Bangalore, India
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Deeg CA, Amann B, Lutz K, Hirmer S, Lutterberg K, Kremmer E, Hauck SM. Aquaporin 11, a regulator of water efflux at retinal Müller glial cell surface decreases concomitant with immune-mediated gliosis. J Neuroinflammation 2016; 13:89. [PMID: 27107718 PMCID: PMC4842293 DOI: 10.1186/s12974-016-0554-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 04/18/2016] [Indexed: 12/13/2022] Open
Abstract
Background Müller glial cells are important regulators of physiological function of retina. In a model disease of retinal inflammation and spontaneous recurrent uveitis in horses (ERU), we could show that retinal Müller glial cells significantly change potassium and water channel protein expression during autoimmune pathogenesis. The most significantly changed channel protein in neuroinflammatory ERU was aquaporin 11 (AQP11). Aquaporins (AQP, 13 members) are important regulators of water and small solute transport through membranes. AQP11 is an unorthodox member of this family and was assigned to a third group of AQPs because of its difference in amino acid sequence (conserved sequence is only 11 %) and especially its largely unknown function. Methods In order to gain insight into the distribution, localization, and function of AQP11 in the retina, we first developed a novel monoclonal antibody for AQP11 enabling quantification, localization, and functional studies. Results In the horse retina, AQP11 was exclusively expressed at Müller glial cell membranes. In uveitic condition, AQP11 disappeared from gliotic Müller cells concomitant with glutamine synthase. Since function of AQP11 is still under debate, we assessed the impact of AQP11 channel on cell volume regulation of primary Müller glial cells under different osmotic conditions. We conclude a concomitant role for AQP11 with AQP4 in water efflux from these glial cells, which is disturbed in ERU. This could probably contribute to swelling and subsequent severe complication of retinal edema through impaired intracellular fluid regulation. Conclusions Therefore, AQP11 is important for physiological Müller glia function and the expression pattern and function of this water channel seems to have distinct functions in central nervous system. The significant reduction in neuroinflammation points to a crucial role in pathogenesis of autoimmune uveitis.
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Affiliation(s)
- Cornelia A Deeg
- Experimental Ophthalmology, Philipps University of Marburg, Baldingerstrasse, 35033, Marburg, Germany. .,Department of Veterinary Sciences, Institute of Animal Physiology, Ludwig-Maximilians University, Veterinärstr. 13, 80539, München, Germany.
| | - Barbara Amann
- Department of Veterinary Sciences, Institute of Animal Physiology, Ludwig-Maximilians University, Veterinärstr. 13, 80539, München, Germany
| | - Konstantin Lutz
- Department of Veterinary Sciences, Institute of Animal Physiology, Ludwig-Maximilians University, Veterinärstr. 13, 80539, München, Germany
| | - Sieglinde Hirmer
- Department of Veterinary Sciences, Institute of Animal Physiology, Ludwig-Maximilians University, Veterinärstr. 13, 80539, München, Germany
| | - Karina Lutterberg
- Department of Veterinary Sciences, Institute of Animal Physiology, Ludwig-Maximilians University, Veterinärstr. 13, 80539, München, Germany
| | - Elisabeth Kremmer
- Helmholtz Zentrum München-German Research Center for Environmental Health (GmbH), Institute for Molecular Immunology, Marchioninistraße 25, 81377, München, Germany
| | - Stefanie M Hauck
- Department of Protein Science, Helmholtz Zentrum München-German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, 85764, Neuherberg, Germany
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Lindskog C, Asplund A, Catrina A, Nielsen S, Rützler M. A Systematic Characterization of Aquaporin-9 Expression in Human Normal and Pathological Tissues. J Histochem Cytochem 2016; 64:287-300. [PMID: 27026296 DOI: 10.1369/0022155416641028] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 03/01/2016] [Indexed: 11/22/2022] Open
Abstract
AQP9 is known to facilitate hepatocyte glycerol uptake. Murine AQP9 protein expression has been verified in liver, skin, epididymis, epidermis and neuronal cells using knockout mice. Further expression sites have been reported in humans. We aimed to verify AQP9 expression in a large set of human normal organs, different cancer types, rheumatoid arthritis synovial biopsies as well as in cell lines and primary cells. Combining standardized immunohistochemistry with high-throughput mRNA sequencing, we found that AQP9 expression in normal tissues was limited, with high membranous expression only in hepatocytes. In cancer tissues, AQP9 expression was mainly found in hepatocellular carcinomas, suggesting no general contribution of AQP9 to carcinogenesis. AQP9 expression in a subset of rheumatoid arthritis synovial tissue samples was affected by Humira, thereby supporting a suggested role of TNFα in AQP9 regulation in this disease. Among cell lines and primary cells, LP-1 myeloma cells expressed high levels of AQP9, whereas low expression was observed in a few other lymphoid cell lines. AQP9 mRNA and protein expression was absent in HepG2 hepatocellular carcinoma cells. Overall, AQP9 expression in human tissues appears to be more selective than in mice.
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Affiliation(s)
- Cecilia Lindskog
- Science for Life Laboratory, Department of Immunology Genetics and Pathology, Uppsala University, Uppsala, Sweden (CL, AA)
| | - Anna Asplund
- Science for Life Laboratory, Department of Immunology Genetics and Pathology, Uppsala University, Uppsala, Sweden (CL, AA)
| | - Anca Catrina
- Rheumatology Clinic, Department of Medicine, Karolinska Institutet at Karolinska University Hospital, Stockholm, Sweden (AC)
| | - Søren Nielsen
- Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden (SN, MR)
| | - Michael Rützler
- Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden (SN, MR),Institute for Health Science and Technology, Aalborg University, Aalborg Ø, Denmark (MR)
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Tran TL, Bek T, la Cour M, Prause JU, Hamann S, Heegaard S. Aquaporin-1 Expression in Retinal Pigment Epithelial Cells Overlying Retinal Drusen. Ophthalmic Res 2016; 55:180-4. [DOI: 10.1159/000443207] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 12/07/2015] [Indexed: 11/19/2022]
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Salik D, Motulsky E, Gregoire F, Delforge V, Bolaky N, Caspers L, Perret J, Willermain F, Delporte C. Modification of aquaporin expression in response to fenretinide-induced transdifferentiation of ARPE-19 cells into neuronal-like cells. Acta Ophthalmol 2016; 94:e59-67. [PMID: 26389809 DOI: 10.1111/aos.12837] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 07/22/2015] [Indexed: 12/15/2022]
Abstract
PURPOSE The goal of this study was to investigate the modifications of aquaporin (AQP) expression in ARPE-19 cells in response to fenretinide-induced transdifferentiation into neuronal-like cells METHODS ARPE-19 cells were treated daily for 7 days with 3 μm fenretinide or dimethyl sulphoxide as control. mRNA and protein expression were evaluated by real-time quantitative PCR, Western blot analysis and immunofluorescence. RESULTS Control ARPE-19 cells expressed AQP1, AQP4, AQP6 and AQP11 at the mRNA level, but only AQP4, AQP6 and AQP11 at the protein level. Fenretinide induced the transdifferentiation of ARPE-19 cells into neuronal-like cells. Indeed, fenretinide induced morphological changes similar to neurons characterized by elongated cell body and the formation of neurite branching. Moreover, ARPE-19 cells transdifferentiated to neuron-like cells were characterized by significant decrease in retinal pigmented epithelium markers, for example cytokeratin 8 and cellular retinaldehyde-binding protein, as well as an increase in neuronal markers such as synaptophysin and calretinin. AQP4 expression, at both mRNA and protein levels, and AQP6 expression, only at protein level, were significantly decreased in ARPE-19 cells transdifferentiated into neuronal-like cells. CONCLUSIONS The expression of AQP4 and AQP6 is downregulated during fenretinide-induced transdifferentiation.
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Affiliation(s)
- Dany Salik
- Laboratory of Pathophysiological and Nutritional Biochemistry; Université Libre de Bruxelles; Brussels Belgium
- Department of Ophthalmology; CHU Saint-Pierre and Brugmann; Brussels Belgium
| | - Elie Motulsky
- Laboratory of Pathophysiological and Nutritional Biochemistry; Université Libre de Bruxelles; Brussels Belgium
- Department of Ophthalmology; CHU Saint-Pierre and Brugmann; Brussels Belgium
| | - Françoise Gregoire
- Laboratory of Pathophysiological and Nutritional Biochemistry; Université Libre de Bruxelles; Brussels Belgium
| | - Valérie Delforge
- Laboratory of Pathophysiological and Nutritional Biochemistry; Université Libre de Bruxelles; Brussels Belgium
| | - Nargis Bolaky
- Laboratory of Pathophysiological and Nutritional Biochemistry; Université Libre de Bruxelles; Brussels Belgium
| | - Laure Caspers
- Department of Ophthalmology; CHU Saint-Pierre and Brugmann; Brussels Belgium
| | - Jason Perret
- Laboratory of Pathophysiological and Nutritional Biochemistry; Université Libre de Bruxelles; Brussels Belgium
| | - François Willermain
- Department of Ophthalmology; CHU Saint-Pierre and Brugmann; Brussels Belgium
- I.R.I.B.H.M; Brussels Belgium
| | - Christine Delporte
- Laboratory of Pathophysiological and Nutritional Biochemistry; Université Libre de Bruxelles; Brussels Belgium
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Giblin JP, Comes N, Strauss O, Gasull X. Ion Channels in the Eye: Involvement in Ocular Pathologies. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2015; 104:157-231. [PMID: 27038375 DOI: 10.1016/bs.apcsb.2015.11.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The eye is the sensory organ of vision. There, the retina transforms photons into electrical signals that are sent to higher brain areas to produce visual sensations. In the light path to the retina, different types of cells and tissues are involved in maintaining the transparency of avascular structures like the cornea or lens, while others, like the retinal pigment epithelium, have a critical role in the maintenance of photoreceptor function by regenerating the visual pigment. Here, we have reviewed the roles of different ion channels expressed in ocular tissues (cornea, conjunctiva and neurons innervating the ocular surface, lens, retina, retinal pigment epithelium, and the inflow and outflow systems of the aqueous humor) that are involved in ocular disease pathophysiologies and those whose deletion or pharmacological modulation leads to specific diseases of the eye. These include pathologies such as retinitis pigmentosa, macular degeneration, achromatopsia, glaucoma, cataracts, dry eye, or keratoconjunctivitis among others. Several disease-associated ion channels are potential targets for pharmacological intervention or other therapeutic approaches, thus highlighting the importance of these channels in ocular physiology and pathophysiology.
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Affiliation(s)
- Jonathan P Giblin
- Universitat de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Nuria Comes
- Universitat de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | | | - Xavier Gasull
- Universitat de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.
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Jang SY, Lee ES, Ohn YH, Park TK. Expression of Aquaporin-6 in Rat Retinal Ganglion Cells. Cell Mol Neurobiol 2015; 36:965-970. [DOI: 10.1007/s10571-015-0283-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 10/03/2015] [Indexed: 11/24/2022]
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Laforenza U, Bottino C, Gastaldi G. Mammalian aquaglyceroporin function in metabolism. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:1-11. [PMID: 26456554 DOI: 10.1016/j.bbamem.2015.10.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 10/05/2015] [Accepted: 10/07/2015] [Indexed: 11/26/2022]
Abstract
Aquaglyceroporins are integral membrane proteins that are permeable to glycerol as well as water. The movement of glycerol from a tissue/organ to the plasma and vice versa requires the presence of different aquaglyceroporins that can regulate the entrance or the exit of glycerol across the plasma membrane. Actually, different aquaglyceroporins have been discovered in the adipose tissue, small intestine, liver, kidney, heart, skeletal muscle, endocrine pancreas and capillary endothelium, and their differential expression could be related to obesity and the type 2 diabetes. Here we describe the expression and function of different aquaglyceroporins in physiological condition and in obesity and type 2 diabetes, suggesting they are potential therapeutic targets for metabolic disorders.
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Affiliation(s)
| | - Cinzia Bottino
- Department of Molecular Medicine, University of Pavia, Italy
| | - Giulia Gastaldi
- Department of Molecular Medicine, University of Pavia, Italy
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Jukkola P, Gu C. Regulation of neurovascular coupling in autoimmunity to water and ion channels. Autoimmun Rev 2015; 14:258-67. [PMID: 25462580 PMCID: PMC4303502 DOI: 10.1016/j.autrev.2014.11.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 11/15/2014] [Indexed: 12/27/2022]
Abstract
Much progress has been made in understanding autoimmune channelopathies, but the underlying pathogenic mechanisms are not always clear due to broad expression of some channel proteins. Recent studies show that autoimmune conditions that interfere with neurovascular coupling in the central nervous system (CNS) can lead to neurodegeneration. Cerebral blood flow that meets neuronal activity and metabolic demand is tightly regulated by local neural activity. This process of reciprocal regulation involves coordinated actions of a number of cell types, including neurons, glia, and vascular cells. In particular, astrocytic endfeet cover more than 90% of brain capillaries to assist blood-brain barrier (BBB) function, and wrap around synapses and nodes of Ranvier to communicate with neuronal activity. In this review, we highlight four types of channel proteins that are expressed in astrocytes, regarding their structures, biophysical properties, expression and distribution patterns, and related diseases including autoimmune disorders. Water channel aquaporin 4 (AQP4) and inwardly rectifying potassium (Kir4.1) channels are concentrated in astrocytic endfeet, whereas some voltage-gated Ca(2+) and two-pore domain K(+) channels are expressed throughout the cell body of reactive astrocytes. More channel proteins are found in astrocytes under normal and abnormal conditions. This research field will contribute to a better understanding of pathogenic mechanisms underlying autoimmune disorders.
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Affiliation(s)
- Peter Jukkola
- Biomedical Sciences Graduate Program, The Ohio State University, Columbus, OH 43210, USA
| | - Chen Gu
- Biomedical Sciences Graduate Program, The Ohio State University, Columbus, OH 43210, USA; Department of Neuroscience, The Ohio State University, Columbus, OH 43210, USA.
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Willermain F, Libert S, Motulsky E, Salik D, Caspers L, Perret J, Delporte C. Origins and consequences of hyperosmolar stress in retinal pigmented epithelial cells. Front Physiol 2014; 5:199. [PMID: 24910616 PMCID: PMC4038854 DOI: 10.3389/fphys.2014.00199] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 05/09/2014] [Indexed: 01/21/2023] Open
Abstract
The retinal pigmented epithelium (RPE) is composed of retinal pigmented epithelial cells joined by tight junctions and represents the outer blood-retinal barrier (BRB). The inner BRB is made of endothelial cells joined by tight junctions and glial extensions surrounding all the retinal blood vessels. One of the functions of the RPE is to maintain an osmotic transepithelial gradient created by ionic pumps and channels, avoiding paracellular flux. Under such physiological conditions, transcellular water movement follows the osmotic gradient and flows normally from the retina to the choroid through the RPE. Several diseases, such as diabetic retinopathy, are characterized by the BRB breakdown leading to leakage of solutes, proteins, and fluid from the retina and the choroid. The prevailing hypothesis explaining macular edema formation during diabetic retinopathy incriminates the inner BRB breakdown resulting in increased osmotic pressure leading in turn to massive water accumulation that can affect vision. Under these conditions, it has been hypothesized that RPE is likely to be exposed to hyperosmolar stress at its apical side. This review summarizes the origins and consequences of osmotic stress in the RPE. Ongoing and further research advances will clarify the mechanisms, at the molecular level, involved in the response of the RPE to osmotic stress and delineate potential novel therapeutic targets and tools.
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Affiliation(s)
- François Willermain
- Department of Ophthalmology, CHU Saint-Pierre and Brugmann Brussels, Belgium ; I.R.I.B.H.M, Université Libre de Bruxelles Brussels, Belgium
| | - Sarah Libert
- Department of Ophthalmology, CHU Saint-Pierre and Brugmann Brussels, Belgium ; Laboratory of Pathophysiological and Nutritional Biochemistry, Department of Biochemistry, Université Libre de Bruxelles Brussels, Belgium
| | - Elie Motulsky
- Department of Ophthalmology, CHU Saint-Pierre and Brugmann Brussels, Belgium ; Laboratory of Pathophysiological and Nutritional Biochemistry, Department of Biochemistry, Université Libre de Bruxelles Brussels, Belgium
| | - Dany Salik
- Department of Ophthalmology, CHU Saint-Pierre and Brugmann Brussels, Belgium ; Laboratory of Pathophysiological and Nutritional Biochemistry, Department of Biochemistry, Université Libre de Bruxelles Brussels, Belgium
| | - Laure Caspers
- Department of Ophthalmology, CHU Saint-Pierre and Brugmann Brussels, Belgium
| | - Jason Perret
- Laboratory of Pathophysiological and Nutritional Biochemistry, Department of Biochemistry, Université Libre de Bruxelles Brussels, Belgium
| | - Christine Delporte
- Laboratory of Pathophysiological and Nutritional Biochemistry, Department of Biochemistry, Université Libre de Bruxelles Brussels, Belgium
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Tran TL, Bek T, la Cour M, Nielsen S, Prause JU, Hamann S, Heegaard S. Altered aquaporin expression in glaucoma eyes. APMIS 2014; 122:772-80. [DOI: 10.1111/apm.12225] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 10/31/2013] [Indexed: 01/07/2023]
Affiliation(s)
- Thuy Linh Tran
- Eye Pathology Institute; Department of Neuroscience and Pharmacology; University of Copenhagen; Copenhagen Denmark
| | - Toke Bek
- Department of Ophthalmology; Aarhus University Hospital; Aarhus Denmark
| | - Morten la Cour
- Department of Ophthalmology; Glostrup Hospital; University of Copenhagen; Copenhagen Denmark
| | - Søren Nielsen
- Department of Biomedicin; Aarhus University; Aarhus Denmark
| | - Jan Ulrik Prause
- Eye Pathology Institute; Department of Neuroscience and Pharmacology; University of Copenhagen; Copenhagen Denmark
| | - Steffen Hamann
- Department of Ophthalmology; Glostrup Hospital; University of Copenhagen; Copenhagen Denmark
| | - Steffen Heegaard
- Eye Pathology Institute; Department of Neuroscience and Pharmacology; University of Copenhagen; Copenhagen Denmark
- Department of Ophthalmology; Glostrup Hospital; University of Copenhagen; Copenhagen Denmark
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Ishibashi K, Tanaka Y, Morishita Y. The role of mammalian superaquaporins inside the cell. Biochim Biophys Acta Gen Subj 2013; 1840:1507-12. [PMID: 24189537 DOI: 10.1016/j.bbagen.2013.10.039] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 10/18/2013] [Accepted: 10/23/2013] [Indexed: 01/06/2023]
Abstract
BACKGROUND The mammalian two superaquaporins, AQP11 and AQP12, are present inside the cell and their null phenotypes in mice suggest their unusual functions. SCOPE OF REVIEW The surveyed literature on these superaquaporins and our unpublished data has been incorporated to speculate their roles. MAJOR CONCLUSIONS AQP11 and AQP12 have unique NPA boxes with a signature cysteine residue. Although some water permeability of AQP11 was demonstrated in liposomes and cultured cells, its permeability to glycerol is unknown. The function of AQP12 still remains to be clarified. AQP11 null mice develop polycystic kidneys following large intracellular vacuoles in the proximal tubule, which may be caused by ER stress or vesicle fusion failure. The role of AQP11 in the kidney and liver seems to alleviate the tissue damage and facilitate the recovery. Its expression in the sperm, thymus and brain suggests its potential roles in these organs in spite of the apparently normal null phenotype. Although AQP12 null mice appear normal, they suffer from severe pancreatitis, suggesting its role in the fusion of zymogen granules. GENERAL SIGNIFICANCE As many issues are unsolved, the clarification of the function and roles of the superaquaporin may lead to the identification of new roles of AQPs. This article is part of a Special Issue entitled Aquaporins.
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Affiliation(s)
- Kenichi Ishibashi
- Department of Medical Physiology, School of Pharmacy, Meiji Pharmaceutical University, Tokyo, Japan.
| | - Yasuko Tanaka
- Department of Medical Physiology, School of Pharmacy, Meiji Pharmaceutical University, Tokyo, Japan
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Schey KL, Wang Z, L Wenke J, Qi Y. Aquaporins in the eye: expression, function, and roles in ocular disease. Biochim Biophys Acta Gen Subj 2013; 1840:1513-23. [PMID: 24184915 DOI: 10.1016/j.bbagen.2013.10.037] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 10/22/2013] [Accepted: 10/23/2013] [Indexed: 12/13/2022]
Abstract
BACKGROUND All thirteen known mammalian aquaporins have been detected in the eye. Moreover, aquaporins have been identified as playing essential roles in ocular functions ranging from maintenance of lens and corneal transparency to production of aqueous humor to maintenance of cellular homeostasis and regulation of signal transduction in the retina. SCOPE OF REVIEW This review summarizes the expression and known functions of ocular aquaporins and discusses their known and potential roles in ocular diseases. MAJOR CONCLUSIONS Aquaporins play essential roles in all ocular tissues. Remarkably, not all aquaporin function as a water permeable channel and the functions of many aquaporins in ocular tissues remain unknown. Given their vital roles in maintaining ocular function and their roles in disease, aquaporins represent potential targets for future therapeutic development. GENERAL SIGNIFICANCE Since aquaporins play key roles in ocular physiology, an understanding of these functions is important to improving ocular health and treating diseases of the eye. It is likely that future therapies for ocular diseases will rely on modulation of aquaporin expression and/or function. This article is part of a Special Issue entitled Aquaporins.
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Affiliation(s)
- Kevin L Schey
- Department of Biochemistry, Vanderbilt School of Medicine, Vanderbilt University, Nashville, TN 37232, USA.
| | - Zhen Wang
- Department of Biochemistry, Vanderbilt School of Medicine, Vanderbilt University, Nashville, TN 37232, USA
| | - Jamie L Wenke
- Department of Biochemistry, Vanderbilt School of Medicine, Vanderbilt University, Nashville, TN 37232, USA
| | - Ying Qi
- Department of Biochemistry, Vanderbilt School of Medicine, Vanderbilt University, Nashville, TN 37232, USA
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