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Wagner K, Unger L, Salman MM, Kitchen P, Bill RM, Yool AJ. Signaling Mechanisms and Pharmacological Modulators Governing Diverse Aquaporin Functions in Human Health and Disease. Int J Mol Sci 2022; 23:1388. [PMID: 35163313 PMCID: PMC8836214 DOI: 10.3390/ijms23031388] [Citation(s) in RCA: 55] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 01/18/2022] [Accepted: 01/20/2022] [Indexed: 02/07/2023] Open
Abstract
The aquaporins (AQPs) are a family of small integral membrane proteins that facilitate the bidirectional transport of water across biological membranes in response to osmotic pressure gradients as well as enable the transmembrane diffusion of small neutral solutes (such as urea, glycerol, and hydrogen peroxide) and ions. AQPs are expressed throughout the human body. Here, we review their key roles in fluid homeostasis, glandular secretions, signal transduction and sensation, barrier function, immunity and inflammation, cell migration, and angiogenesis. Evidence from a wide variety of studies now supports a view of the functions of AQPs being much more complex than simply mediating the passive flow of water across biological membranes. The discovery and development of small-molecule AQP inhibitors for research use and therapeutic development will lead to new insights into the basic biology of and novel treatments for the wide range of AQP-associated disorders.
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Affiliation(s)
- Kim Wagner
- School of Biomedicine, University of Adelaide, Adelaide, SA 5005, Australia;
| | - Lucas Unger
- College of Health and Life Sciences, Aston University, Birmingham B4 7ET, UK; (L.U.); (P.K.)
| | - Mootaz M. Salman
- Department of Physiology Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK;
- Oxford Parkinson’s Disease Centre, University of Oxford, South Parks Road, Oxford OX1 3QX, UK
| | - Philip Kitchen
- College of Health and Life Sciences, Aston University, Birmingham B4 7ET, UK; (L.U.); (P.K.)
| | - Roslyn M. Bill
- College of Health and Life Sciences, Aston University, Birmingham B4 7ET, UK; (L.U.); (P.K.)
| | - Andrea J. Yool
- School of Biomedicine, University of Adelaide, Adelaide, SA 5005, Australia;
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Fan X, Bilir EK, Kingston OA, Oldershaw RA, Kearns VR, Willoughby CE, Sheridan CM. Replacement of the Trabecular Meshwork Cells-A Way Ahead in IOP Control? Biomolecules 2021; 11:biom11091371. [PMID: 34572584 PMCID: PMC8464777 DOI: 10.3390/biom11091371] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 09/09/2021] [Accepted: 09/13/2021] [Indexed: 12/11/2022] Open
Abstract
Glaucoma is one of the leading causes of vision loss worldwide, characterised with irreversible optic nerve damage and progressive vision loss. Primary open-angle glaucoma (POAG) is a subset of glaucoma, characterised by normal anterior chamber angle and raised intraocular pressure (IOP). Reducing IOP is the main modifiable factor in the treatment of POAG, and the trabecular meshwork (TM) is the primary site of aqueous humour outflow (AH) and the resistance to outflow. The structure and the composition of the TM are key to its function in regulating AH outflow. Dysfunction and loss of the TM cells found in the natural ageing process and more so in POAG can cause abnormal extracellular matrix (ECM) accumulation, increased TM stiffness, and increased IOP. Therefore, repair or regeneration of TM's structure and function is considered as a potential treatment for POAG. Cell transplantation is an attractive option to repopulate the TM cells in POAG, but to develop a cell replacement approach, various challenges are still to be addressed. The choice of cell replacement covers autologous or allogenic approaches, which led to investigations into TM progenitor cells, induced pluripotent stem cells (iPSCs), and mesenchymal stem cells (MSCs) as potential stem cell source candidates. However, the potential plasticity and the lack of definitive cell markers for the progenitor and the TM cell population compound the biological challenge. Morphological and differential gene expression of TM cells located within different regions of the TM may give rise to different cell replacement or regenerative approaches. As such, this review describes the different approaches taken to date investigating different cell sources and their differing cell isolation and differentiation methodologies. In addition, we highlighted how these approaches were evaluated in different animal and ex vivo model systems and the potential of these methods in future POAG treatment.
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Affiliation(s)
- Xiaochen Fan
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool L69 3BX, UK; (X.F.); (E.K.B.); (O.A.K.); (V.R.K.)
| | - Emine K. Bilir
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool L69 3BX, UK; (X.F.); (E.K.B.); (O.A.K.); (V.R.K.)
| | - Olivia A. Kingston
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool L69 3BX, UK; (X.F.); (E.K.B.); (O.A.K.); (V.R.K.)
| | - Rachel A. Oldershaw
- Department of Musculoskeletal and Ageing Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool L69 3BX, UK;
| | - Victoria R. Kearns
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool L69 3BX, UK; (X.F.); (E.K.B.); (O.A.K.); (V.R.K.)
| | - Colin E. Willoughby
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool L69 3BX, UK; (X.F.); (E.K.B.); (O.A.K.); (V.R.K.)
- Genomic Medicine, Biomedical Sciences Research Institute, Ulster University, Coleraine BT52 1SA, UK
- Correspondence: (C.E.W.); (C.M.S.); Tel.: +44-(28)-701-2338 (C.E.W.); +44-(151)-794-9031 (C.M.S.)
| | - Carl M. Sheridan
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool L69 3BX, UK; (X.F.); (E.K.B.); (O.A.K.); (V.R.K.)
- Correspondence: (C.E.W.); (C.M.S.); Tel.: +44-(28)-701-2338 (C.E.W.); +44-(151)-794-9031 (C.M.S.)
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Huang OS, Seet LF, Ho HW, Chu SW, Narayanaswamy A, Perera SA, Husain R, Aung T, Wong TT. Altered Iris Aquaporin Expression and Aqueous Humor Osmolality in Glaucoma. Invest Ophthalmol Vis Sci 2021; 62:34. [PMID: 33616622 PMCID: PMC7910645 DOI: 10.1167/iovs.62.2.34] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Aquaporins (AQPs) facilitate transmembrane osmotic water transport and may play a role in iris fluid conductivity, which is implicated in the pathophysiology of glaucoma. In this study, we compared the iris expression of AQPs and aqueous osmolality between primary angle closure glaucoma (PACG), primary open-angle glaucoma (POAG), and nonglaucoma eyes. Methods AQP1-5 transcripts from a cohort of 36 PACG, 34 POAG and 26 nonglaucoma irises were measured by quantitative real-time PCR. Osmolality of aqueous humor from another cohort of 49 PACG, 50 POAG, and 50 nonglaucoma eyes were measured using an osmometer. The localization of AQP1 in both glaucoma and nonglaucoma irises was determined by immunofluorescent analysis. Results Of the five AQP genes evaluated, AQP1 and AQP2 transcripts were significantly upregulated in both PACG (3.48- and 8.07-fold, respectively) and POAG (3.12- and 11.58-fold, respectively) irises relative to nonglaucoma counterparts. The aqueous osmolalities of PACG (303.68 mmol/kg) and POAG (300.79 mmol/kg) eyes were significantly lower compared to nonglaucoma eyes (312.6 mmol/kg). There was no significant difference in expression of AQP transcripts or aqueous osmolality between PACG and POAG eyes. Conclusions PACG and POAG eyes featured significant increase in AQP1 and AQP2 expression in the iris and reduced aqueous osmolality compared to nonglaucoma eyes. These findings suggest that the iris may be involved in altered aqueous humor dynamics in glaucoma pathophysiology. Because PACG did not differ from POAG in both properties studied, it is likely that they are common to glaucoma disease in general.
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Affiliation(s)
- Olivia S Huang
- Singapore National Eye Centre, Singapore.,Duke-NUS Medical School, Singapore
| | - Li-Fong Seet
- Singapore Eye Research Institute, Singapore.,Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.,Duke-NUS Medical School, Singapore
| | | | | | | | - Shamira A Perera
- Singapore National Eye Centre, Singapore.,Singapore Eye Research Institute, Singapore.,Duke-NUS Medical School, Singapore
| | - Rahat Husain
- Singapore National Eye Centre, Singapore.,Singapore Eye Research Institute, Singapore.,Duke-NUS Medical School, Singapore
| | - Tin Aung
- Singapore National Eye Centre, Singapore.,Singapore Eye Research Institute, Singapore.,Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.,Duke-NUS Medical School, Singapore
| | - Tina T Wong
- Singapore National Eye Centre, Singapore.,Singapore Eye Research Institute, Singapore.,Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.,Duke-NUS Medical School, Singapore.,School of Materials Science and Engineering, Nanyang Technological University, Singapore
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Li X, He F, Gabelt BT, Wang Y, Cai S, Cao J, Fan N, Kaufman PL, Liu X. Effects of Latanoprost and Bimatoprost on the Expression of Molecules Relevant to Ocular Inflow and Outflow Pathways. PLoS One 2016; 11:e0151644. [PMID: 27011234 PMCID: PMC4807090 DOI: 10.1371/journal.pone.0151644] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Accepted: 03/02/2016] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND AND PURPOSE The intraocular pressure (IOP)-lowering and side effects in response to different prostaglandin F2α analogues can be variable, but, the underlying basis for this difference remains unknown. This study investigated the differential changes of cellular proteins relevant to IOP-lowering effects of latanoprost and bimatoprost. METHODS The human T lymphoblast (MOLT-3) cell line and immortalized human trabecular meshwork (iHTM) cells were studied by quantitative PCR and by immunofluorescence after treatment with either latanoprost or bimatoprost. New Zealand white rabbit eyes were treated topically with each agent and, following euthanasia, anterior segment tissues were studied with immunostaining. RESULTS In cultured MOLT-3 cells, mRNA expression of both c-fos and matrix metalloproteinase 9 increased significantly in response to each agent. In addition, there was little change in tissue inhibitor of metalloproteinase (TIMP)-3 mRNA, but a significant decrease in TIMP-4. Fibronectin mRNA in MOLT-3 cells was down-regulated with bimatoprost, but was up-regulated with latanoprost. Immunofluorescence analysis of iHTM cells showed that intracellular fibronectin was significantly decreased by bimatoprost, but was increased by latanoprost. Both latanoprost and bimatoprost increased mRNA expression of NF-кB p65 and decreased that of IкBα. Aquaporin-1 mRNA expression was significantly down-regulated by bimatoprost. Immunostaining also revealed a significant decrease of aquaporin-1 in the ciliary epithelium of New Zealand white rabbits after bimatoprost treatment. CONCLUSIONS Similarities in protein expression produced by latanoprost and bimatoprost in vitro may be relevant to the mechanism for their IOP-lowering effects in vivo. Differences in fibronectin expression and in aquaporin-1 expression in response to each agent may contribute to variability in the IOP-lowering efficacy in some studies.
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Affiliation(s)
- Xiaohong Li
- Department of Biopharmaceutics, Key Laboratory of Drug Targeting and Drug Delivery Systems, Ministry of Education, West China School of Pharmacy, Sichuan University, Chengdu, China
| | - Fen He
- State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
| | - B’Ann T. Gabelt
- Department of Ophthalmology & Visual Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Yun Wang
- Shenzhen Key Laboratory of Ophthalmology, Shenzhen Eye Hospital, Shenzhen University, Shenzhen, China
| | - Suping Cai
- Shenzhen Key Laboratory of Ophthalmology, Shenzhen Eye Hospital, Shenzhen University, Shenzhen, China
| | - Juanhui Cao
- Shenzhen Key Laboratory of Ophthalmology, Shenzhen Eye Hospital, Shenzhen University, Shenzhen, China
| | - Ning Fan
- Shenzhen Key Laboratory of Ophthalmology, Shenzhen Eye Hospital, Shenzhen University, Shenzhen, China
| | - Paul L. Kaufman
- Department of Ophthalmology & Visual Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Xuyang Liu
- Shenzhen Key Laboratory of Ophthalmology, Shenzhen Eye Hospital, Shenzhen University, Shenzhen, China
- * E-mail:
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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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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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Mark HH. Aqueous humor dynamics in historical perspective. Surv Ophthalmol 2010; 55:89-100. [PMID: 19783023 DOI: 10.1016/j.survophthal.2009.06.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2009] [Revised: 06/18/2009] [Accepted: 06/18/2009] [Indexed: 10/20/2022]
Abstract
In antiquity the aqueous humor was seen as essential to moisten and nourish the lens- the actual organ of vision-and therefore any loss was believed to lead to blindness. The recuperation of the eye after some aqueous loss during cataract couching and experimental loss in animals slowly undermined this idea in the 16(th) and 17(th) centuries. In the 18(th) century production of aqueous from the ciliary region and its outflow from the anterior chamber, and thus its circulation, was generally accepted. Early in the 19(th) century the aqueous was thought to be encapsulated, but by the end of the century the general dynamic principles of aqueous flow as we know them today were experimentally and clinically confirmed. The controversy concerning its mode of production and circulation that took place early in the 20(th) century was resolved with the discovery of the aqueous veins and advances in molecular biology.
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Affiliation(s)
- Harry H Mark
- Yale-New Haven Hospital, New Haven, Connecticut, USA.
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Liu W, Liu Y, Qin XJ, Schmidt S, Hauser MA, Allingham RR. AQP1 and SLC4A10 as candidate genes for primary open-angle glaucoma. Mol Vis 2010; 16:93-7. [PMID: 20101282 PMCID: PMC2810210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Accepted: 01/15/2010] [Indexed: 12/05/2022] Open
Abstract
PURPOSE Recent evidence supports the role of reduced cerebrospinal fluid (CSF) pressure in the pathogenesis of primary open-angle glaucoma (POAG). We investigated the association of variants in two candidate genes that are important in CSF production, aquaporin 1 (AQP1) and solute carrier family 4, sodium bicarbonate transporter, member 10 (SLC4A10), with POAG in the Caucasian population. METHODS POAG subjects (n=382) met the criteria of glaucomatous optic neuropathy with consistent visual field loss. Intraocular pressure was not used as an inclusion criterion. Control subjects (n=363) did not meet any of the inclusion criteria and had no family history of glaucoma. Eleven tagging single nucleotide polymorphisms (SNPs) for AQP1 and SLC4A10 were genotyped in the POAG and control subjects, using allelic discrimination assays. Genotype frequencies were compared between the POAG and control subjects, using logistic regression adjusted for gender. RESULTS There was no statistically significant difference in genotype frequencies between POAG and control subjects for any of the tested SNPs in AQP1 and SLC4A10 (p>0.05). CONCLUSIONS There was no association between common sequence variants in the AQP1 or SLC4A10 genes and POAG in the Caucasian population. This is the first study to investigate the association between these two candidate genes and increased risk for POAG.
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Affiliation(s)
- Wenjing Liu
- Center for Human Genetics, Duke University Eye Center, Duke University Medical Center, Durham, NC
| | - Yutao Liu
- Center for Human Genetics, Duke University Eye Center, Duke University Medical Center, Durham, NC
| | - Xue-Jun Qin
- Center for Human Genetics, Duke University Eye Center, Duke University Medical Center, Durham, NC
| | - Silke Schmidt
- Center for Human Genetics, Duke University Eye Center, Duke University Medical Center, Durham, NC
| | - Michael A. Hauser
- Center for Human Genetics, Duke University Eye Center, Duke University Medical Center, Durham, NC
- Department of Ophthalmology, Duke University Eye Center, Duke University Medical Center, Durham, NC
| | - R. Rand Allingham
- Center for Human Genetics, Duke University Eye Center, Duke University Medical Center, Durham, NC
- Department of Ophthalmology, Duke University Eye Center, Duke University Medical Center, Durham, NC
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Baetz NW, Hoffman EA, Yool AJ, Stamer WD. Role of aquaporin-1 in trabecular meshwork cell homeostasis during mechanical strain. Exp Eye Res 2009; 89:95-100. [PMID: 19268465 DOI: 10.1016/j.exer.2009.02.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2008] [Revised: 01/14/2009] [Accepted: 02/24/2009] [Indexed: 10/21/2022]
Abstract
Aquaporin-1 (AQP1) channels are expressed by trabecular meshwork (TM) and Schlemm's canal cells of the conventional outflow pathway where fluid movement is predominantly paracellular, suggesting a non-canonical role for AQP1. We hypothesized that AQP1 functions to protect TM cells during periods of mechanical strain. To test this idea, primary cultures of confluent human TM cells on Bioflex membranes were exposed to static and cyclic stretch for 8 and 24h using the Flexcell system. AQP1 expression in TM cells was assessed by SDS-PAGE and Western blot using anti-AQP1 IgGs. AQP1 protein bands were analyzed using densitometry and normalized to beta-actin expression. Cell damage was monitored by measuring lactate dehydrogenase (LDH) and histone deacetylase appearance in conditioned media. Recombinant expression of AQP1 in TM cell cultures was facilitated by transduction with adenovirus. Results show that AQP1 expression significantly increased 2-fold with 10% static stretch and 3.5-fold with 20% static stretch at 8h (n=4, p<0.05) and 24h (n=6, p<0.05). While histone deacetylase levels were unaffected by treatments, release of LDH from TM cells was the most profound at the 20% static stretch level (n=4, p<0.05). Significantly, cells were refractory to the 20% static stretch level when AQP1 expression was increased to near tissue levels. Analysis of LDH release with respect to AQP1 expression revealed an inverse linear relationship (r(2)=0.7780). Taken together, AQP1 in human TM appears to serve a protective role by facilitating improved cell viability during conditions of mechanical strain.
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Affiliation(s)
- N W Baetz
- Department of Cell Biology and Anatomy, University of Arizona, Tucson, AZ, USA
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