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Qin M, Yu-Wai-Man C. Glaucoma: Novel antifibrotic therapeutics for the trabecular meshwork. Eur J Pharmacol 2023; 954:175882. [PMID: 37391006 PMCID: PMC10804937 DOI: 10.1016/j.ejphar.2023.175882] [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: 04/03/2023] [Revised: 06/23/2023] [Accepted: 06/26/2023] [Indexed: 07/02/2023]
Abstract
Glaucoma is a chronic and progressive neurodegenerative disease characterized by the loss of retinal ganglion cells and visual field defects, and currently affects around 1% of the world's population. Elevated intraocular pressure (IOP) is the best-known modifiable risk factor and a key therapeutic target in hypertensive glaucoma. The trabecular meshwork (TM) is the main site of aqueous humor outflow resistance and therefore a critical regulator of IOP. Fibrosis, a reparative process characterized by the excessive deposition of extracellular matrix components and contractile myofibroblasts, can impair TM function and contribute to the pathogenesis of primary open-angle glaucoma (POAG) as well as the failure of minimally invasive glaucoma surgery (MIGS) devices. This paper provides a detailed overview of the current anti-fibrotic therapeutics targeting the TM in glaucoma, along with their anti-fibrotic mechanisms, efficacy as well as the current research progress from pre-clinical to clinical studies.
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Affiliation(s)
- Mengqi Qin
- King's College London, London, SE1 7EH, UK
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2
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Carreon TA, Castellanos A, Gasull X, Bhattacharya SK. Interaction of cochlin and mechanosensitive channel TREK-1 in trabecular meshwork cells influences the regulation of intraocular pressure. Sci Rep 2017; 7:452. [PMID: 28352076 PMCID: PMC5428432 DOI: 10.1038/s41598-017-00430-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 02/28/2017] [Indexed: 12/18/2022] Open
Abstract
In the eye, intraocular pressure (IOP) is tightly regulated and its persistent increase leads to ocular hypertension and glaucoma. We have previously shown that trabecular meshwork (TM) cells might detect aqueous humor fluid shear stress via interaction of the extracellular matrix (ECM) protein cochlin with the cell surface bound and stretch-activated channel TREK-1. We provide evidence here that interaction between both proteins are involved in IOP regulation. Silencing of TREK-1 in mice prevents the previously demonstrated cochlin-overexpression mediated increase in IOP. Biochemical and electrophysiological experiments demonstrate that high shear stress-induced multimeric cochlin produces a qualitatively different interaction with TREK-1 compared to monomeric cochlin. Physiological concentrations of multimeric but not monomeric cochlin reduce TREK-1 current. Results presented here indicate that the interaction of TREK-1 and cochlin play an important role for maintaining IOP homeostasis. [Corrected].
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Affiliation(s)
- Teresia A Carreon
- Bascom Palmer Eye Institute, University of Miami, Miami, Florida, USA.,Department of Biochemistry and Molecular Biology, University of Miami, Miami, USA
| | - Aida Castellanos
- Department of Biomedicine, University of Barcelona, Barcelona, Spain.,Institut d'Investigaciones Biomediques August Pi I Sunyer (IDIBAPS), Barcelona, Spain.,Institute of Neurosciences, University of Barcelona, Barcelona, Spain
| | - Xavier Gasull
- Department of Biomedicine, University of Barcelona, Barcelona, Spain.,Institut d'Investigaciones Biomediques August Pi I Sunyer (IDIBAPS), Barcelona, Spain.,Institute of Neurosciences, University of Barcelona, Barcelona, Spain
| | - Sanjoy K Bhattacharya
- Bascom Palmer Eye Institute, University of Miami, Miami, Florida, USA. .,Department of Biochemistry and Molecular Biology, University of Miami, Miami, USA.
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3
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Ryskamp DA, Frye AM, Phuong TTT, Yarishkin O, Jo AO, Xu Y, Lakk M, Iuso A, Redmon SN, Ambati B, Hageman G, Prestwich GD, Torrejon KY, Križaj D. TRPV4 regulates calcium homeostasis, cytoskeletal remodeling, conventional outflow and intraocular pressure in the mammalian eye. Sci Rep 2016; 6:30583. [PMID: 27510430 PMCID: PMC4980693 DOI: 10.1038/srep30583] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 07/04/2016] [Indexed: 01/20/2023] Open
Abstract
An intractable challenge in glaucoma treatment has been to identify druggable targets within the conventional aqueous humor outflow pathway, which is thought to be regulated/dysregulated by elusive mechanosensitive protein(s). Here, biochemical and functional analyses localized the putative mechanosensitive cation channel TRPV4 to the plasma membrane of primary and immortalized human TM (hTM) cells, and to human and mouse TM tissue. Selective TRPV4 agonists and substrate stretch evoked TRPV4-dependent cation/Ca2+ influx, thickening of F-actin stress fibers and reinforcement of focal adhesion contacts. TRPV4 inhibition enhanced the outflow facility and lowered perfusate pressure in biomimetic TM scaffolds populated with primary hTM cells. Systemic delivery, intraocular injection or topical application of putative TRPV4 antagonist prodrug analogs lowered IOP in glaucomatous mouse eyes and protected retinal neurons from IOP-induced death. Together, these findings indicate that TRPV4 channels function as a critical component of mechanosensitive, Ca2+-signaling machinery within the TM, and that TRPV4-dependent cytoskeletal remodeling regulates TM stiffness and outflow. Thus, TRPV4 is a potential IOP sensor within the conventional outflow pathway and a novel target for treating ocular hypertension.
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Affiliation(s)
- Daniel A Ryskamp
- Department of Ophthalmology &Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.,Interdepartmental Program in Neuroscience, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Amber M Frye
- Department of Ophthalmology &Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Tam T T Phuong
- Department of Ophthalmology &Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Oleg Yarishkin
- Department of Ophthalmology &Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Andrew O Jo
- Department of Ophthalmology &Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Yong Xu
- Department of Medicinal Chemistry, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Monika Lakk
- Department of Ophthalmology &Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.,Interdepartmental Program in Neuroscience, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Anthony Iuso
- Department of Ophthalmology &Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.,Interdepartmental Program in Neuroscience, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Sarah N Redmon
- Department of Ophthalmology &Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.,Interdepartmental Program in Neuroscience, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Balamurali Ambati
- Department of Ophthalmology &Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Gregory Hageman
- Department of Ophthalmology &Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.,Center for Translational Medicine, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Glenn D Prestwich
- Department of Medicinal Chemistry, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | | | - David Križaj
- Department of Ophthalmology &Visual Sciences, Moran Eye Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.,Interdepartmental Program in Neuroscience, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.,Center for Translational Medicine, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.,Department of Neurobiology &Anatomy, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.,Department of Bioengineering, University of Utah, Salt Lake City, UT 84112, USA
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4
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Gonzalez JM, Ko MK, Pouw A, Tan JCH. Tissue-based multiphoton analysis of actomyosin and structural responses in human trabecular meshwork. Sci Rep 2016; 6:21315. [PMID: 26883567 PMCID: PMC4756353 DOI: 10.1038/srep21315] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 01/21/2016] [Indexed: 01/15/2023] Open
Abstract
The contractile trabecular meshwork (TM) modulates aqueous humor outflow resistance and intraocular pressure. The primary goal was to visualize and quantify human TM contractile state by analyzing actin polymerization (F-actin) by 2-photon excitation fluorescence imaging (TPEF) in situ. A secondary goal was to ascertain if structural extracellular matrix (ECM) configuration changed with contractility. Viable ex vivo human TM was incubated with latrunculin-A (Lat-A) or vehicle prior to Alexa-568-phalloidin labeling and TPEF. Quantitative image analysis was applied to 2-dimensional (2D) optical sections and 3D image reconstructions. After Lat-A exposure, (a) the F-actin network reorganized as aggregates; (b) F-actin-associated fluorescence intensity was reduced by 48.6% (mean; p = 0.007; n = 8); (c) F-actin 3D distribution was reduced by 68.9% (p = 0.040); (d) ECM pore cross-sectional area and volume were larger by 36% (p = 0.032) and 65% (p = 0.059) respectively and pores appeared more interconnected; (e) expression of type I collagen and elastin, key TM structural ECM proteins, were unaltered (p = 0.54); and (f) tissue viability was unchanged (p = 0.39) relative to vehicle controls. Thus Lat-A-induced reduction of actomyosin contractility was associated with TM porous expansion without evidence of reduced structural ECM protein expression or cellular viability. These important subcellular-level dynamics could be visualized and quantified within human tissue by TPEF.
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Affiliation(s)
- Jose M Gonzalez
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Minhee K Ko
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Andrew Pouw
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - James C H Tan
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA
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Roubeix C, Godefroy D, Mias C, Sapienza A, Riancho L, Degardin J, Fradot V, Ivkovic I, Picaud S, Sennlaub F, Denoyer A, Rostene W, Sahel JA, Parsadaniantz SM, Brignole-Baudouin F, Baudouin C. Intraocular pressure reduction and neuroprotection conferred by bone marrow-derived mesenchymal stem cells in an animal model of glaucoma. Stem Cell Res Ther 2015; 6:177. [PMID: 26377305 PMCID: PMC4574127 DOI: 10.1186/s13287-015-0168-0] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 01/28/2015] [Accepted: 08/21/2015] [Indexed: 12/13/2022] Open
Abstract
INTRODUCTION Glaucoma is a sight-threatening retinal neuropathy associated with elevated intraocular pressure (IOP) due to degeneration and fibrosis of the trabecular meshwork (TM). Glaucoma medications aim to reduce IOP without targeting the specific TM pathology, Bone-marrow mesenchymal stem cells (MSCs) are used today in various clinical studies. Here, we investigated the potential of MSCs therapy in an glaucoma-like ocular hypertension (OHT) model and decipher in vitro the effects of MSCs on primary human trabecular meshwork cells. METHODS Ocular hypertension model was performed by cauterization of 3 episcleral veins (EVC) of Long-Evans male rat eyes. MSCs were isolated from rat bone marrow, amplified in vitro and tagged with quantum dot nanocrystals. Animals were distributed as 1) MSCs group receiving 5.10(5)cells/6μl Minimum Essential Medium and 2) MEM group receiving 6μl MEM (n = 10 each). Injections were performed into the anterior chamber of 20 days-hypertensive eyes and IOP was monitored twice a week for 4 weeks. At the end of experiment, cell distribution in the anterior segment was examined in confocal microscopy on flat mounted corneas. Moreover, we tested in vitro effects of MSCs conditioned medium (MSC-CM) on primary human trabecular meshwork cells (hTM cells) using Akt activation, myosin phosphorylation and TGF-β2-dependent profibrotic phenotype in hTM cells. RESULTS We demonstrated a rapid and long-lasting in vivo effect of MSCs transplantation that significantly reduced IOP in hypertensive eyes induced by EVC. MSCs were located to the ciliary processes and the TM. Enumeration of RGCs on whole flat-mounted retina highlighted a protective effect of MSCs on RGCs death. In vitro, MSC-CM promotes: (i) hTM cells survival by activating the antiapoptotic pathway, Akt, (ii) hTM cells relaxation as analyzed by the decrease in myosin phosphorylation and (iii) inhibition of TGF-β2-dependent profibrotic phenotype acquisition in hTM cells. CONCLUSIONS MSCs injection in the ocular anterior chamber in a rat model of OHT provides neuroprotective effect in the glaucoma pathophysiology via TM protection. These results demonstrate that MSCs constitute promising tool for treating ocular hypertension and retinal cell degeneration.
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Affiliation(s)
- Christophe Roubeix
- INSERM, U968, Paris, F-75012, France.
- UPMC Université Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France.
- CNRS, UMR_7210, Paris, F-75012, France.
| | - David Godefroy
- INSERM, U968, Paris, F-75012, France.
- UPMC Université Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France.
- CNRS, UMR_7210, Paris, F-75012, France.
| | - Céline Mias
- Institut des Maladies Métaboliques et Cardiovasculaires, INSERM UMR 1048, 31432 Toulouse cedex 4, France, Toulouse, France.
| | - Anaïs Sapienza
- INSERM, U968, Paris, F-75012, France.
- UPMC Université Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France.
- CNRS, UMR_7210, Paris, F-75012, France.
| | - Luisa Riancho
- INSERM, U968, Paris, F-75012, France.
- UPMC Université Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France.
- CNRS, UMR_7210, Paris, F-75012, France.
| | - Julie Degardin
- INSERM, U968, Paris, F-75012, France.
- UPMC Université Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France.
- CNRS, UMR_7210, Paris, F-75012, France.
| | - Valérie Fradot
- INSERM, U968, Paris, F-75012, France.
- UPMC Université Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France.
- CNRS, UMR_7210, Paris, F-75012, France.
| | - Ivana Ivkovic
- INSERM, U968, Paris, F-75012, France.
- UPMC Université Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France.
- CNRS, UMR_7210, Paris, F-75012, France.
| | - Serge Picaud
- INSERM, U968, Paris, F-75012, France.
- UPMC Université Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France.
- CNRS, UMR_7210, Paris, F-75012, France.
| | - Florian Sennlaub
- INSERM, U968, Paris, F-75012, France.
- UPMC Université Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France.
- CNRS, UMR_7210, Paris, F-75012, France.
| | - Alexandre Denoyer
- INSERM, U968, Paris, F-75012, France.
- UPMC Université Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France.
- CNRS, UMR_7210, Paris, F-75012, France.
- Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, INSERM-DHOS CIC 503, Paris, F-75012, France.
| | - William Rostene
- INSERM, U968, Paris, F-75012, France.
- UPMC Université Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France.
- CNRS, UMR_7210, Paris, F-75012, France.
| | - José Alain Sahel
- INSERM, U968, Paris, F-75012, France.
- UPMC Université Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France.
- CNRS, UMR_7210, Paris, F-75012, France.
- Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, INSERM-DHOS CIC 503, Paris, F-75012, France.
| | - Stéphane Melik Parsadaniantz
- INSERM, U968, Paris, F-75012, France.
- UPMC Université Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France.
- CNRS, UMR_7210, Paris, F-75012, France.
| | - Françoise Brignole-Baudouin
- INSERM, U968, Paris, F-75012, France.
- UPMC Université Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France.
- CNRS, UMR_7210, Paris, F-75012, France.
- Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, INSERM-DHOS CIC 503, Paris, F-75012, France.
- University Paris Descartes, Sorbonne Paris Cité, Paris, F-75006, France.
- Faculté de Pharmacie de Paris, University Paris Descartes, Sorbonne Paris Cité, Paris, F-75006, France.
| | - Christophe Baudouin
- INSERM, U968, Paris, F-75012, France.
- UPMC Université Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France.
- CNRS, UMR_7210, Paris, F-75012, France.
- Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, INSERM-DHOS CIC 503, Paris, F-75012, France.
- Department of Ophthalmology, Hôpital Ambroise Pare, AP HP, Boulogne, F-92100, France.
- University Versailles St Quentin en Yvelines, Montigny-Le-Bretonneux, F-78180, France.
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Huete-Toral F, Crooke A, Martínez-Águila A, Pintor J. Melatonin receptors trigger cAMP production and inhibit chloride movements in nonpigmented ciliary epithelial cells. J Pharmacol Exp Ther 2014; 352:119-28. [PMID: 25344385 DOI: 10.1124/jpet.114.218263] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Melatonin and its analog 5-MCA-NAT (5-methylcarboxyamino-N-acetyl tryptamine) are active compounds reducing intraocular pressure (IOP). This action is mediated through MT2 and the putative MT3 melatonin receptor, producing a transient reduction of IOP that lasts for a few hours and has not yet been characterized. The use of melatonin and its analog are causing a decrease in chloride efflux from rabbit nonpigmented epithelial cells (NPE), possibly explaining the decrease in IOP. Melatonin and 5-MCA-NAT inhibited rabbit NPE chloride release in a concentration-dependent manner, whereas the pD2 values were between 4.5 ± 1.2 and 4.4 ± 1.0, respectively. Melatonin hypotensive action was enhanced by the presence of MT2 antagonists, such as DH97 (N-pentanoyl-2-benzyltryptamine) and 4-P-P-DOT (4-phenyl-2-propionamidotetralin) and by the nonselective melatonin receptor antagonist luzindole. Prazosin (1.5 µM) partially reverses the melatonin action by acting as a selective MT3 antagonist. However, at 15 nM it acts as an α-adrenergic receptor antagonist, enhancing the melatonin effect. Regarding the intracellular pathways triggered by melatonin receptors, neither phospholipase C/protein kinase C pathway nor the canonical reduction of intracellular cAMP was responsible for melatonin or 5-MCA-NAT actions. On the contrary, the application of these substances produced a concentration-dependent increase of cAMP, with pD2 values of 4.6 ± 0.2 and 4.9 ± 0.7 for melatonin and 5-MCA-NAT, respectively. In summary, melatonin reduces the release of chloride concomitantly to cAMP generation. The reduction of Cl(-) secretion accounts for a decrease in the water outflow and therefore a decrease in aqueous humor production. This could be one of the main mechanisms responsible for the reduction of IOP after application of melatonin and 5-MCA-NAT.
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Affiliation(s)
- Fernando Huete-Toral
- Departamento de Bioquímica y Biología Molecular IV, Facultad de Óptica y Optometría, Universidad Complutense de Madrid, Madrid, Spain
| | - Almudena Crooke
- Departamento de Bioquímica y Biología Molecular IV, Facultad de Óptica y Optometría, Universidad Complutense de Madrid, Madrid, Spain
| | - Alejandro Martínez-Águila
- Departamento de Bioquímica y Biología Molecular IV, Facultad de Óptica y Optometría, Universidad Complutense de Madrid, Madrid, Spain
| | - Jesús Pintor
- Departamento de Bioquímica y Biología Molecular IV, Facultad de Óptica y Optometría, Universidad Complutense de Madrid, Madrid, Spain
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Rao PV. Bioactive lysophospholipids: role in regulation of aqueous humor outflow and intraocular pressure in the context of pathobiology and therapy of glaucoma. J Ocul Pharmacol Ther 2014; 30:181-90. [PMID: 24283588 PMCID: PMC3991961 DOI: 10.1089/jop.2013.0194] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 10/23/2013] [Indexed: 01/21/2023] Open
Abstract
Homeostasis of aqueous humor (AH) outflow and intraocular pressure (IOP) is essential for normal vision. Impaired AH outflow through the trabecular meshwork (TM) and a resultant elevation in IOP are common changes in primary open-angle glaucoma (POAG), which is the most prevalent form of glaucoma. Although elevated IOP has been recognized as a definitive risk factor for POAG and lowering elevated IOP remains a mainstay for glaucoma treatment, little is known about the molecular mechanisms, especially external cues and intracellular pathways, involved in the regulation of AH outflow in both normal and glaucomatous eyes. In addition, despite the recognition that increased resistance to AH outflow via the conventional pathway consisting of TM and Schlemm's canal is the main cause for elevated IOP, there are no clinically approved drugs that target the conventional pathway to lower IOP in glaucoma patients. The aim of this article is to briefly review published work on the importance of bioactive lysophospholipids (eg, lysophosphatidic acid and sphingosine-1-phosphate), their receptors, metabolism, signaling, and role in the regulation of AH outflow via the TM and IOP, and to discuss pharmacological targeting of key proteins in the lysophospholipid signaling pathways to lower IOP in glaucoma patients.
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Affiliation(s)
- Ponugoti Vasantha Rao
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina
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8
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Pattabiraman PP, Pecen PE, Rao PV. MRP4-mediated regulation of intracellular cAMP and cGMP levels in trabecular meshwork cells and homeostasis of intraocular pressure. Invest Ophthalmol Vis Sci 2013; 54:1636-49. [PMID: 23385799 PMCID: PMC3626514 DOI: 10.1167/iovs.12-11107] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 01/07/2013] [Accepted: 01/26/2013] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Multidrug, resistance-associated protein-4 (MRP4) is a membrane transporter that regulates the cellular efflux of cyclic nucleotides (cAMP and cGMP) involved in various physiologic responses. This study examined the expression and distribution of MRP4 in the trabecular meshwork (TM) cells and its role in homeostasis of IOP. METHODS Expression and distribution of MRP4 in human TM (HTM) cells and aqueous humor (AH) outflow pathway was determined by RT-PCR, immunoblotting, and immunofluorescence. Effects of inhibiting MRP4 activity and suppression of MRP4 expression on cAMP and cGMP levels, myosin light chain (MLC) phosphorylation, actin filament organization and activity of protein kinase G (PKG), protein kinase A (PKA), Rho guanosine triphosphatase (GTPase), and MLC phosphatase was monitored in HTM cells using ELISA, siRNA, biochemical, and immunofluorescence analyses. Topical application of the MRP4 inhibitor MK571 was tested to assess changes in IOP in rabbits. RESULTS RT-PCR, immunoblot, and immunofluorescence analyses confirmed the expression of MRP4 in HTM cells and distribution in human AH outflow pathway. Inhibition of MRP4 in HTM cells by MK571 or probenecid resulted in cell shape changes and decreases in actin stress fibers and MLC phosphorylation. Levels of intracellular cAMP and cGMP in HTM cells were increased significantly under these conditions. MK571-induced HTM cell relaxation appeared to be mediated predominantly via activation of the cGMP-dependent PKG signaling pathway. Topical application of MK571 significantly decreased IOP in Dutch-Belted rabbits. CONCLUSIONS These observations reveal that cyclic nucleotide efflux controlling transporter-MRP4 plays a significant role in IOP homeostasis potentially by regulating the relaxation characteristics of AH outflow pathway cells.
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Affiliation(s)
| | | | - Ponugoti Vasantha Rao
- From the Departments of
Ophthalmology and
- Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina
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10
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Elimam H, Papillon J, Takano T, Cybulsky AV. Complement-mediated activation of calcium-independent phospholipase A2γ: role of protein kinases and phosphorylation. J Biol Chem 2012; 288:3871-85. [PMID: 23258543 DOI: 10.1074/jbc.m112.396614] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In experimental membranous nephropathy, complement C5b-9-induces glomerular epithelial cell (GEC) injury and proteinuria. The effects of C5b-9 are mediated via signaling pathways, including calcium-independent phospholipase A(2)γ (iPLA(2)γ), and mitogen-activated protein kinases (MAPKs) such as extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38. The iPLA(2)γ pathway is cytoprotective. This study addresses the mechanisms of iPLA(2)γ activation. iPLA(2)γ activity was monitored by quantifying prostaglandin E(2) (PGE(2)) production. In GECs, iPLA(2)γ localized at the endoplasmic reticulum and mitochondria. Complement-mediated production of PGE(2) was amplified in GECs that overexpress iPLA(2)γ, compared with control cells, and was blocked by the iPLA(2)γ inhibitor bromoenol lactone in both iPLA(2)γ-overexpressing and control GECs. In GECs that overexpress iPLA(2)γ, complement-mediated PGE(2) production was reduced by inhibitors of MAP/ERK kinase 1 (MEK1) and p38 but not JNK. In COS-1 cells that overexpress iPLA(2)γ and cyclooxygenase-1, PGE(2) production was induced by co-expression of constitutively active MEK1 or MAPK-interacting kinase 1 (MNK1) as well as by stimulation with epidermal growth factor (EGF) + ionomycin. Complement- and EGF + ionomycin-stimulated iPLA(2)γ activity was attenuated by the S511A/S515A double mutation. Moreover, complement and EGF + ionomycin enhanced phosphorylation of Ser-511. Thus, complement-mediated activation of iPLA(2)γ is mediated via ERK and p38 pathways, and phosphorylation of Ser-511 and/or Ser-515 plays a key role in the catalytic activity and signaling of iPLA(2)γ. Defining the mechanisms by which complement activates iPLA(2)γ provides opportunities for development of novel therapeutic approaches to GEC injury and proteinuria.
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Affiliation(s)
- Hanan Elimam
- Department of Medicine, McGill University Health Centre, McGill University, Montreal, Quebec H3A 1A1, Canada
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Iyer P, Lalane R, Morris C, Challa P, Vann R, Rao PV. Autotaxin-lysophosphatidic acid axis is a novel molecular target for lowering intraocular pressure. PLoS One 2012; 7:e42627. [PMID: 22916143 PMCID: PMC3423407 DOI: 10.1371/journal.pone.0042627] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 07/09/2012] [Indexed: 11/18/2022] Open
Abstract
Primary open-angle glaucoma is the second leading cause of blindness in the United States and is commonly associated with elevated intraocular pressure (IOP) resulting from diminished aqueous humor (AH) drainage through the trabecular pathway. Developing effective therapies for increased IOP in glaucoma patients requires identification and characterization of molecular mechanisms that regulate IOP and AH outflow. This study describes the identification and role of autotaxin (ATX), a secretory protein and a major source for extracellular lysophosphatidic acid (LPA), in regulation of IOP in a rabbit model. Quantitative proteomics analysis identified ATX as an abundant protein in both human AH derived from non-glaucoma subjects and in AH from different animal species. The lysophospholipase D (LysoPLD) activity of ATX was found to be significantly elevated (by ∼1.8 fold; n=20) in AH derived from human primary open angle glaucoma patients as compared to AH derived from age-matched cataract control patients. Immunoblotting analysis of conditioned media derived from primary cultures of human trabecular meshwork (HTM) cells has confirmed secretion of ATX and the ability of cyclic mechanical stretch of TM cells to increase the levels of secreted ATX. Topical application of a small molecular chemical inhibitor of ATX (S32826), which inhibited AH LysoPLD activity in vitro (by >90%), led to a dose-dependent and significant decrease of IOP in Dutch-Belted rabbits. Single intracameral injection of S32826 (∼2 µM) led to significant reduction of IOP in rabbits, with the ocular hypotensive response lasting for more than 48 hrs. Suppression of ATX expression in HTM cells using small-interfering RNA (siRNA) caused a decrease in actin stress fibers and myosin light chain phosphorylation. Collectively, these observations indicate that the ATX-LPA axis represents a potential therapeutic target for lowering IOP in glaucoma patients.
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Affiliation(s)
- Padma Iyer
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Robert Lalane
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Corey Morris
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Pratap Challa
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Robin Vann
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Ponugoti Vasantha Rao
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States of America
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina, United States of America
- * E-mail:
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Crooke A, Huete-Toral F, Martínez-Águila A, Colligris B, Pintor J. Ocular disorders and the utility of animal models in the discovery of melatoninergic drugs with therapeutic potential. Expert Opin Drug Discov 2012; 7:989-1001. [PMID: 22860991 DOI: 10.1517/17460441.2012.714769] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
INTRODUCTION The pineal indole-derived hormone melatonin is a modulator of circadian and seasonal rhythms with an important role in ocular health and disease. This could be due to specific melatonin receptors that have been identified in structures such as cornea, lens, ciliary body, retina, choroid and sclera. In addition, a local synthesis of melatonin occurs in several of these ocular tissues. AREAS COVERED The authors review existing literature on the most common animal models where ocular melatonin actions have been tested. The therapeutic potential of melatonin in diabetic keratopathy and retinopathy, keratitis, cataracts, glaucoma, uveitis, age-related macular degeneration and retinitis pigmentosa is discussed. Furthermore, the authors comment on the usefulness of different animal models for the development of melatoninergic drugs with therapeutic potential. EXPERT OPINION The use of animals for the study of ocular diseases and the potentiality of melatonin and its analogs, as future therapeutic drugs, should be performed on the basis of a rationale study. It is important to note that melatonin receptors seem to be widespread all over the eye. This strongly suggests that, in order to modify the physiology and biochemistry of malfunctioning ocular tissue, the melatonin receptors which are present in that tissue must be first identified. Second there is the need to confirm that those receptors targeted perform the desirable responses, and as a third measure, to use selective agonists (or antagonists) instead of melatonin. However, although some animals mimic ocular pathologies relatively well, and these can be used in melatonin studies, there is still a long way to go till some of the results obtained in animal models could be used for human therapy.
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Affiliation(s)
- Almudena Crooke
- Departamento de Bioquímica y Biología Molecular IV, E.U. Óptica, Universidad Complutense de Madrid, C/Arcos de Jalón 118, Madrid, Spain
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