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Carracedo G, Garcia-Gonzalo C, Perez-Luque MA, Martinez-Aguila A, Carpena-Torres C. Efficacy and safety of artificial tears containing Artemia salina extract with dinucleotides for dry eye. Clin Exp Optom 2024:1-7. [PMID: 38653499 DOI: 10.1080/08164622.2024.2341841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 04/05/2024] [Indexed: 04/25/2024] Open
Abstract
CLINICAL RELEVANCE This clinical trial was conducted as part of the marketing procedures for a medical device comprising artificial tears containing Artemia salina extract with dinucleotides. These molecules previously demonstrated secretagogue properties by enhancing the production of aqueous, mucinous, and lipidic components of the tears. BACKGROUND After confirming the efficacy of artificial tears containing Artemia salina extract in an animal model, this study proceeded to evaluate their efficacy and safety on dry eye participants. METHODS A randomised controlled clinical trial was performed on 36 dry eye participants (41.6 ± 20.6 years). Half of the participants were treated with saline solution as a placebo for four weeks, while the other half were treated with artificial tears containing Artemia salina, randomly assigned. After a wash-out period of two weeks, the treatments were crossed for another four weeks. Participants were assessed at baseline and after one week, two weeks, and four weeks. Efficacy variables were: eye dryness frequency (primary), eye comfort, visual satisfaction, tear secretion, tear break-up time, corneal staining, conjunctival staining, and conjunctival hyperaemia. Safety variables were: high- and low-contrast visual acuity, intraocular pressure, and eye fundus images analysis. RESULTS Compared with the baseline, the saline solution showed no significant changes in any of the studied variables after four weeks of treatment (p ≥ 0.05). However, the topical instillation of the artificial tears with Artemia salina for four weeks significantly improved eye dryness frequency (p = 0.014) and corneal staining (p = 0.010). No systemic or ocular adverse events were reported during the clinical trial. CONCLUSION The topical instillation of artificial tears containing Artemia salina in mild to moderate dry eye participants for four weeks slightly improved their symptoms related to eye dryness frequency and reduced corneal damage, with no undesirable side effects observed.
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Affiliation(s)
- Gonzalo Carracedo
- Ocupharm Research Group, Department of Optometry and Vision, Faculty of Optics and Optometry, Complutense University of Madrid, Madrid, Spain
| | - Cristina Garcia-Gonzalo
- Ocupharm Research Group, Department of Optometry and Vision, Faculty of Optics and Optometry, Complutense University of Madrid, Madrid, Spain
| | - Maria A Perez-Luque
- Ocupharm Research Group, Department of Optometry and Vision, Faculty of Optics and Optometry, Complutense University of Madrid, Madrid, Spain
| | - Alejandro Martinez-Aguila
- Ocupharm Research Group, Department of Biochemistry and Molecular Biology, Faculty of Optics and Optometry, Complutense University of Madrid, Madrid, Spain
| | - Carlos Carpena-Torres
- Ocupharm Research Group, Department of Optometry and Vision, Faculty of Optics and Optometry, Complutense University of Madrid, Madrid, Spain
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Zhou J, Ding Y, Zhang Y, Zheng D, Yan L, Guo M, Mao Y, Yang L. Exosomes from bone marrow-derived mesenchymal stem cells facilitate corneal wound healing via regulating the p44/42 MAPK pathway. Graefes Arch Clin Exp Ophthalmol 2023; 261:723-734. [PMID: 36576571 DOI: 10.1007/s00417-022-05956-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 12/04/2022] [Accepted: 12/21/2022] [Indexed: 12/29/2022] Open
Abstract
PURPOSE This study was aimed at exploring the function of Exosomes isolated from bone marrow-derived mesenchymal stem cells (BMSC-Exos) in corneal wound healing and at revealing the underlying mechanisms involving the p44/42 mitogen-activated protein kinase (MAPK) pathway. METHODS The isolated BMSC-Exos were identified by transmission electron microscopy, Western blot, and nanoparticle tracking analysis. After coculture with BMSC-Exos, the proliferation and migration of human corneal epithelial cells (HCEs) were evaluated. The protein expression of p-MEK/MEK and p44/42 MAPK was detected by Western blot. A mouse model of alkali-burned cornea was established via NaOH exposure. After injection with BMSC-Exos, the pathological changes and expression of α-SMA (a fibrosis marker) and CD31 (a vascularization marker) in corneal tissues were detected. RESULTS BMSC-Exos enhanced the proliferation and migration of HCEs in a dose-dependent manner. The p44/42 MAPK pathway was activated by the treatment of BMSC-Exos, and its blocking using U0126 partially abrogated the effects of BMSC-Exos on promoting the proliferation and migration of HCEs. In vivo, the injection of BMSC-Exos facilitated the remission of the pathological changes (inflammation) and weakened the upregulation of α-SMA (fibrosis) and CD31 (vascularization) in corneal tissues of mice with alkali-burn injury. CONCLUSION BMSC-Exos promoted the proliferation and migration of HCEs via activating the p44/42 MAPK pathway in vitro and also inhibited alkali burn-induced inflammation, fibrosis, and vascularization in corneal tissues in vivo. BMSC-Exos may be promising resources for promoting corneal wound healing.
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Affiliation(s)
- Jin Zhou
- Department of Ophthalmology, Guangzhou Women and Children's Medical Center, No. 9, Jinsui Road, Tianhe District, Guangzhou City, 510623, China.
| | - Yuanyuan Ding
- Department of Ophthalmology, Nanfang Hospital, Southern Medical University, Guangzhou City, 510515, China
| | - Yongqiang Zhang
- Department of Ophthalmology, Beijing Children's Hospital East Branch, Beijing City, 100002, China
| | - Dehui Zheng
- Department of Ophthalmology, Guangzhou Women and Children's Medical Center, No. 9, Jinsui Road, Tianhe District, Guangzhou City, 510623, China
| | - Lifeng Yan
- Department of Ophthalmology, Guangzhou Women and Children's Medical Center, No. 9, Jinsui Road, Tianhe District, Guangzhou City, 510623, China
| | - Mengxiang Guo
- Department of Ophthalmology, Guangzhou Women and Children's Medical Center, No. 9, Jinsui Road, Tianhe District, Guangzhou City, 510623, China
| | - Yani Mao
- Department of Ophthalmology, Guangzhou Women and Children's Medical Center, No. 9, Jinsui Road, Tianhe District, Guangzhou City, 510623, China
| | - Lihong Yang
- Department of Ophthalmology, Guangzhou Women and Children's Medical Center, No. 9, Jinsui Road, Tianhe District, Guangzhou City, 510623, China
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MAPK Pathways in Ocular Pathophysiology: Potential Therapeutic Drugs and Challenges. Cells 2023; 12:cells12040617. [PMID: 36831285 PMCID: PMC9954064 DOI: 10.3390/cells12040617] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 02/05/2023] [Accepted: 02/07/2023] [Indexed: 02/17/2023] Open
Abstract
Mitogen-activated protein kinase (MAPK) pathways represent ubiquitous cellular signal transduction pathways that regulate all aspects of life and are frequently altered in disease. Once activated through phosphorylation, these MAPKs in turn phosphorylate and activate transcription factors present either in the cytoplasm or in the nucleus, leading to the expression of target genes and, as a consequence, they elicit various biological responses. The aim of this work is to provide a comprehensive review focusing on the roles of MAPK signaling pathways in ocular pathophysiology and the potential to influence these for the treatment of eye diseases. We summarize the current knowledge of identified MAPK-targeting compounds in the context of ocular diseases such as macular degeneration, cataract, glaucoma and keratopathy, but also in rare ocular diseases where the cell differentiation, proliferation or migration are defective. Potential therapeutic interventions are also discussed. Additionally, we discuss challenges in overcoming the reported eye toxicity of some MAPK inhibitors.
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Carpena-Torres C, Pintor J, Huete-Toral F, Martin-Gil A, Rodríguez-Pomar C, Martínez-Águila A, Carracedo G. Efficacy of Artificial Tears Based on an Extract of Artemia salina Containing Dinucleotides in a Rabbit Dry Eye Model. Int J Mol Sci 2021; 22:ijms222111999. [PMID: 34769429 PMCID: PMC8584318 DOI: 10.3390/ijms222111999] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Revised: 10/29/2021] [Accepted: 11/03/2021] [Indexed: 11/16/2022] Open
Abstract
(1) Background: Artemia salina is a brine shrimp containing high concentrations of dinucleotides, molecules with properties for dry eye treatment. For this reason, the purpose of the study was to evaluate the effect of the artificial tears based on an extract of Artemia salina in a rabbit dry eye model. (2) Methods: A prospective and randomized study was carried out. Twenty rabbits were divided into 4 groups (n = 5, each group): healthy rabbits, dry eye rabbits, dry eye rabbits treated with hypromellose (HPMC), and dry eye rabbits treated with Artemia salina. Dry eye was induced by the topical instillation of 0.2% benzalkonium chloride. The measurements were performed before and after the treatment for 5 consecutive days. (3) Results: The topical instillation of artificial tears containing Artemia salina showed beneficial effects on tear secretion, tear break-up time, corneal staining, the density of Goblet cells, heigh of mucin cloud secreted by these cells, and mRNA levels of IL-1β and MMP9 in conjunctival cells. Compared with the HPMC, there was a statistically significant improvement (p < 0.05) with the Artemia salina in all the variables under study, except for the conjunctival hyperemia, density of Goblet cells, and mRNA levels of IL-6. (4) Conclusions: The potential of artificial tears based on Artemia salina as a secretagogue agent for dry eye treatment was confirmed, opening the door for future clinical trials and studies to extrapolate the findings for dry eye patients.
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Affiliation(s)
- Carlos Carpena-Torres
- Ocupharm Research Group, Department of Optometry and Vision, Faculty of Optics and Optometry, Complutense University of Madrid, C/Arcos de Jalón 118, 28037 Madrid, Spain; (C.C.-T.); (A.M.-G.); (C.R.-P.)
| | - Jesus Pintor
- Ocupharm Research Group, Department of Biochemistry and Molecular Biology, Faculty of Optics and Optometry, Complutense University of Madrid, C/Arcos de Jalón 118, 28037 Madrid, Spain; (J.P.); (F.H.-T.); (A.M.-Á.)
| | - Fernando Huete-Toral
- Ocupharm Research Group, Department of Biochemistry and Molecular Biology, Faculty of Optics and Optometry, Complutense University of Madrid, C/Arcos de Jalón 118, 28037 Madrid, Spain; (J.P.); (F.H.-T.); (A.M.-Á.)
| | - Alba Martin-Gil
- Ocupharm Research Group, Department of Optometry and Vision, Faculty of Optics and Optometry, Complutense University of Madrid, C/Arcos de Jalón 118, 28037 Madrid, Spain; (C.C.-T.); (A.M.-G.); (C.R.-P.)
| | - Candela Rodríguez-Pomar
- Ocupharm Research Group, Department of Optometry and Vision, Faculty of Optics and Optometry, Complutense University of Madrid, C/Arcos de Jalón 118, 28037 Madrid, Spain; (C.C.-T.); (A.M.-G.); (C.R.-P.)
| | - Alejandro Martínez-Águila
- Ocupharm Research Group, Department of Biochemistry and Molecular Biology, Faculty of Optics and Optometry, Complutense University of Madrid, C/Arcos de Jalón 118, 28037 Madrid, Spain; (J.P.); (F.H.-T.); (A.M.-Á.)
| | - Gonzalo Carracedo
- Ocupharm Research Group, Department of Optometry and Vision, Faculty of Optics and Optometry, Complutense University of Madrid, C/Arcos de Jalón 118, 28037 Madrid, Spain; (C.C.-T.); (A.M.-G.); (C.R.-P.)
- Correspondence:
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Carney BC, Simbulan-Rosenthal CM, Gaur A, Browne BJ, Moghe M, Crooke E, Moffatt LT, Shupp JW, Rosenthal DS. Inorganic polyphosphate in platelet rich plasma accelerates re-epithelialization in vitro and in vivo. Regen Ther 2020; 15:138-148. [PMID: 33426212 PMCID: PMC7770352 DOI: 10.1016/j.reth.2020.07.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 06/25/2020] [Accepted: 07/16/2020] [Indexed: 12/19/2022] Open
Abstract
Wound healing requires well-coordinated events including hemostasis, inflammation, proliferation, and remodeling. Delays in any of these stages leads to chronic wounds, infections, and hypertrophic scarring. Burn wounds are particularly problematic, and may require intervention to ensure timely progression to reduce morbidity and mortality. To accelerate burn wound healing, Platelet-Rich Plasma (PRP)1 can be of value, since platelets release growth factor proteins and inorganic polyphosphates (polyP) that may be integral to wound healing. We used polyP-depleted keratinocyte (HaCaT) and fibroblast cell culture models to determine cell proliferation and scratch-wound repair to determine if polyP, platelet lysate, or combined treatment could accelerate wound healing. While polyP and PRP significantly reduced the open scratch-wound area in fibroblasts and keratinocytes, polyP had no effect on keratinocyte or fibroblast proliferation. PRP was also evaluated as a treatment in a murine model of full thickness wound healing in vivo, including a treatment in which PRP was supplemented with purified polyP. PRP induced significantly more rapid re-epithelialization by Day 3. Pure polyP enhanced the effects of PRP on epithelial tongues, which were significantly elongated in the PRP + high-dose polyP treatment groups compared to PRP alone. Thus, PRP and polyP may serve as an effective therapeutic combination for treating wounds.
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Key Words
- Inorganic polyphosphate
- Keratinocytes
- PPX1 exopolyphosphatase
- Wound healing
- endopolyphosphatase, PPN
- epidermal growth factor, EGF
- exopolyphosphatase, PPX
- human foreskin fibroblasts, HFF
- mammalian target of rapamycin, mTOR
- platelet-derived growth factor, PDGF
- platelet-poor plasma, PPP
- platelet-rich plasma, PRP
- polyP kinase, PPK
- polyphosphates, polyP
- reactive oxygen species, ROS
- total body surface area, TBSA
- transforming growth factor beta, TGFβ
- vacuolar transporter chaperone 4, VTC4
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Affiliation(s)
- Bonnie C. Carney
- Department of Biochemistry and Molecular and Cellular Biology, Georgetown University School of Medicine, Washington, DC, USA
- Firefighters' Burn and Surgical Research Laboratory, MedStar Health Research Institute, Washington, DC, USA
| | - Cynthia M. Simbulan-Rosenthal
- Department of Biochemistry and Molecular and Cellular Biology, Georgetown University School of Medicine, Washington, DC, USA
| | - Anirudh Gaur
- Department of Biochemistry and Molecular and Cellular Biology, Georgetown University School of Medicine, Washington, DC, USA
| | - Benjamin J. Browne
- Firefighters' Burn and Surgical Research Laboratory, MedStar Health Research Institute, Washington, DC, USA
| | - Manish Moghe
- Department of Biochemistry and Molecular and Cellular Biology, Georgetown University School of Medicine, Washington, DC, USA
| | - Elliott Crooke
- Department of Biochemistry and Molecular and Cellular Biology, Georgetown University School of Medicine, Washington, DC, USA
| | - Lauren T. Moffatt
- Department of Biochemistry and Molecular and Cellular Biology, Georgetown University School of Medicine, Washington, DC, USA
- Firefighters' Burn and Surgical Research Laboratory, MedStar Health Research Institute, Washington, DC, USA
| | - Jeffrey W. Shupp
- Department of Biochemistry and Molecular and Cellular Biology, Georgetown University School of Medicine, Washington, DC, USA
- Firefighters' Burn and Surgical Research Laboratory, MedStar Health Research Institute, Washington, DC, USA
- The Burn Center, Department of Surgery, MedStar Washington Hospital Center, Washington, DC, USA
- Department of Surgery, Georgetown University School of Medicine, Washington, DC, USA
| | - Dean S. Rosenthal
- Department of Biochemistry and Molecular and Cellular Biology, Georgetown University School of Medicine, Washington, DC, USA
- Corresponding author. Department of Biochemistry, 3900 Reservoir Road, BSB 333, Washington, DC, 20010, USA.Tel.: 202 687 1056; Fax: 202 687 4632.
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Carpena-Torres C, Pintor J, Huete-Toral F, Rodriguez-Pomar C, Martínez-Águila A, Carracedo G. Preclinical Development of Artificial Tears Based on an Extract of Artemia Salina Containing Dinucleotides in Rabbits. Curr Eye Res 2020; 46:174-178. [PMID: 32602751 DOI: 10.1080/02713683.2020.1789665] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
PURPOSE To evaluate the preclinical efficacy of eye drops based on an extract of Artemia salina on the ocular surface of rabbits. Tear secretion, tear break-up time and corneal staining were measured. MATERIAL AND METHODS A preclinical and short-term prospective study was performed. Twenty New Zealand white rabbits were divided into five groups, with four rabbits per group, each receiving a different concentration of Artemia salina. In each rabbit, an extract of Artemia salina (2%, 4%, 6%, 8% or 10%) was randomly instilled in one eye and saline solution (negative control) in the other eye. Tear secretion, tear break-up time and corneal staining were measured before and after the instillation of five drops per eye (one drop per hour) on the same day. RESULTS In tear secretion, there was an increase of 43.88 ± 6.73% with 4% Artemia salina in comparison with its baseline measurement (P = .049). The rest of the groups did not show differences (P ≥ 0.05). For tear break-up time, none of the groups showed differences (P ≥ 0.05), while for corneal staining score, there was an improvement of 0.88 ± 0.83 with 4% Artemia salina (P = .038) and a deterioration of 0.50 ± 0.83 with control solution (P = .008). CONCLUSIONS Short-term instillation of eye drops with 4% Artemia salina produced both stimulation of tear secretion and a slight improvement of physiological corneal staining. Besides, all the doses of up to 10% Artemia salina did not produce undesirable side effects on the ocular surface. Therefore, these eye drops are presented as a possible new treatment for dry eye due to their secretagogue properties and ocular surface regeneration.
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Affiliation(s)
- Carlos Carpena-Torres
- Department of Optometry and Vision, Faculty of Optics and Optometry, Complutense University of Madrid , Madrid, Spain
| | - Jesús Pintor
- Department of Biochemistry and Molecular Biology, Faculty of Optics and Optometry, Complutense University of Madrid , Madrid, Spain
| | - Fernando Huete-Toral
- Department of Biochemistry and Molecular Biology, Faculty of Optics and Optometry, Complutense University of Madrid , Madrid, Spain
| | - Candela Rodriguez-Pomar
- Department of Optometry and Vision, Faculty of Optics and Optometry, Complutense University of Madrid , Madrid, Spain
| | - Alejandro Martínez-Águila
- Department of Biochemistry and Molecular Biology, Faculty of Optics and Optometry, Complutense University of Madrid , Madrid, Spain
| | - Gonzalo Carracedo
- Department of Optometry and Vision, Faculty of Optics and Optometry, Complutense University of Madrid , Madrid, Spain
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Horváth D, Sipos A, Major E, Kónya Z, Bátori R, Dedinszki D, Szöll Si A, Tamás I, Iván J, Kiss A, Erd di F, Lontay B. Myosin phosphatase accelerates cutaneous wound healing by regulating migration and differentiation of epidermal keratinocytes via Akt signaling pathway in human and murine skin. Biochim Biophys Acta Mol Basis Dis 2018; 1864:3268-3280. [PMID: 30010048 DOI: 10.1016/j.bbadis.2018.07.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 06/24/2018] [Accepted: 07/10/2018] [Indexed: 01/01/2023]
Abstract
Wound healing is a complex sequence of cellular and molecular processes such as inflammation, cell migration, proliferation and differentiation. ROCK is a widely investigated Ser/Thr kinase with important roles in rearranging the actomyosin cytoskeleton. ROCK inhibitors have already been approved to improve corneal endothelial wound healing. The purpose of this study was to investigate the functions of myosin phosphatase (MP or PPP1CB), a type-1 phospho-Ser/Thr-specific protein phosphatase (PP1), one of the counter enzymes of ROCK, in skin homeostasis and wound healing. To confirm our hypotheses, we applied tautomycin (TM), a selective PP1 inhibitor, on murine skin that caused the arrest of wound closure. TM suppressed scratch closure of HaCaT human keratinocytes without having influence on the survival of the cells. Silencing of, the regulatory subunit of MP (MYPT1 or PPP1R12A), had a negative impact on the migration of keratinocytes and it influenced the cell-cell adhesion properties by decreasing the impedance of HaCaT cells. We assume that MP differentially activates migration and differentiation of keratinocytes and plays a key role in the downregulation of transglutaminase-1 in lower layers of skin where no differentiation is required. MAPK Proteome Profiler analysis on human ex vivo biopsies with MYPT1-silencing indicated that MP contributes to the mediation of wound healing by regulating the Akt signaling pathway. Our findings suggest that MP plays a role in the maintenance of normal homeostasis of skin and the process of wound healing.
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Affiliation(s)
- Dániel Horváth
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Adrienn Sipos
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Evelin Major
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Zoltán Kónya
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary; MTA-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Róbert Bátori
- Vascular Biology Center, Augusta University, Augusta, United States
| | - Dóra Dedinszki
- Institute of Enzymology, Hungarian Academy of Sciences, Budapest, Hungary
| | - Attila Szöll Si
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - István Tamás
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Judit Iván
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary; MTA-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Andrea Kiss
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Ferenc Erd di
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary; MTA-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Beáta Lontay
- Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.
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Cui YH, Hu ZX, Gao ZX, Song XL, Feng QY, Yang G, Li ZJ, Pan HW. Airborne particulate matter impairs corneal epithelial cells migration via disturbing FAK/RhoA signaling pathway and cytoskeleton organization. Nanotoxicology 2018; 12:312-324. [PMID: 29463199 DOI: 10.1080/17435390.2018.1440651] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Cornea is the outmost structure of the eye and exposed directly to the air pollution. However, little is known about the effect of PM2.5 on corneal epithelium, which is critical for maintenance of cornea homeostasis and visual function. OBJECTIVE We investigated the influence of PM2.5 exposure on corneal epithelial migration and the possible mechanisms involved in the process. METHODS We observed wound healing in mouse model of cornea abrasion, evaluated the migration and mobility of cultured corneal epithelial cells with wound scratch assay and Transwell migration assay, detected the phosphorylation and interaction of FAK/paxillin with immunofluorescence and immunoprecipitation, and determined the RhoA activity and actin reorganization, in response to PM2.5 exposure. RESULTS Exposure to PM2.5 remarkably inhibited corneal epithelial cell migration both in mouse model of corneal abrasion and in cell culture model. We found the phosphorylation and interaction of FAK/paxillin, RhoA activity as well as actin reorganization were suppressed by PM2.5 exposure. Moreover, formation of ROS might play a role in the action of PM2.5. CONCLUSIONS PM2.5 exposure could result in delay of corneal epithelium wound healing by inhibiting cell migration, thus more attention should be paid to the potential risk of corneal infection and effort should be made to protect eyes against impairment induced by PM2.5.
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Affiliation(s)
- Yu-Hong Cui
- a Guangzhou Institute of Cardiovascular Disease , The Second Affiliated Hospital, School of Basic Medical Sciences, Guangzhou Medical University , Guangzhou , China.,b Department of Histology and Embryology, School of Basic Medical Sciences , Guangzhou Medical University , Guangzhou , China
| | - Zi-Xuan Hu
- c Department of Public Health And Preventive Medicine, School of Medicine , Jinan University , Guangzhou , China
| | - Zi-Xun Gao
- d Institute of Ophthalmology, School of Medicine , Jinan University , Guangzhou , China
| | - Xi-Ling Song
- c Department of Public Health And Preventive Medicine, School of Medicine , Jinan University , Guangzhou , China
| | - Qing-Yang Feng
- e Department of Ophthalmology , Guangdong Women and Children's Hospital , Guangzhou , China
| | - Guang Yang
- c Department of Public Health And Preventive Medicine, School of Medicine , Jinan University , Guangzhou , China
| | - Zhi-Jie Li
- d Institute of Ophthalmology, School of Medicine , Jinan University , Guangzhou , China
| | - Hong-Wei Pan
- c Department of Public Health And Preventive Medicine, School of Medicine , Jinan University , Guangzhou , China.,d Institute of Ophthalmology, School of Medicine , Jinan University , Guangzhou , China
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Crooke A, Guzman-Aranguez A, Carracedo G, de Lara MJP, Pintor J. Understanding the Presence and Roles of Ap 4A (Diadenosine Tetraphosphate) in the Eye. J Ocul Pharmacol Ther 2017; 33:426-434. [PMID: 28414592 DOI: 10.1089/jop.2016.0146] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Diadenosine tetraphosphate abbreviated Ap4A is a naturally occurring dinucleotide, which is present in most of the ocular fluids. Due to its intrinsic resistance to enzyme degradation compared to mononucleotides, this molecule can exhibit profound actions on ocular tissues, including the ocular surface, ciliary body, trabecular meshwork, and probably the retina. The actions of Ap4A are mostly carried out by P2Y2 receptors, but the participation of P2X2 and P2Y6 in processes such as the regulation of intraocular pressure (IOP), together with the P2Y2, is pivotal. Beyond the physiological role, this dinucleotide can present on the ocular surface keeping a right production of tear secretion or regulating IOP. It is important to note that exogenous application of Ap4A to cells or animal models can significantly modify pathophysiological conditions and thus is an attractive therapeutic molecule. The ocular location where Ap4A actions have not been fully elucidated is in the retina. Although some analogues show interesting actions on pathological situations such as retinal detachment, little is known about the real effect of this dinucleotide, this being one of the challenges that require pursuing in the near future.
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Affiliation(s)
- Almudena Crooke
- 1 Departamento de Bioquímica y Biología Molecular, Universidad Complutense de Madrid , Madrid, Spain
| | - Ana Guzman-Aranguez
- 1 Departamento de Bioquímica y Biología Molecular, Universidad Complutense de Madrid , Madrid, Spain
| | - Gonzalo Carracedo
- 2 Departamento de Optometría y Visión, F. Óptica, Universidad Complutense de Madrid , Madrid, Spain
| | - Maria J Perez de Lara
- 1 Departamento de Bioquímica y Biología Molecular, Universidad Complutense de Madrid , Madrid, Spain
| | - Jesus Pintor
- 1 Departamento de Bioquímica y Biología Molecular, Universidad Complutense de Madrid , Madrid, Spain
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Carracedo G, Crooke A, Guzman-Aranguez A, Pérez de Lara MJ, Martin-Gil A, Pintor J. The role of dinucleoside polyphosphates on the ocular surface and other eye structures. Prog Retin Eye Res 2016; 55:182-205. [PMID: 27421962 DOI: 10.1016/j.preteyeres.2016.07.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 06/30/2016] [Accepted: 07/05/2016] [Indexed: 11/17/2022]
Abstract
Dinucleoside polyphosphates comprises a group of dinucleotides formed by two nucleosides linked by a variable number of phosphates, abbreviated NpnN (where n represents the number of phosphates). These compounds are naturally occurring substances present in tears, aqueous humour and in the retina. As the consequence of their presence, these dinucleotides contribute to many ocular physiological processes. On the ocular surface, dinucleoside polyphosphates can stimulate tear secretion, mucin release from goblet cells and they help epithelial wound healing by accelerating cell migration rate. These dinucleotides can also stimulate the presence of proteins known to protect the ocular surface against microorganisms, such as lysozyme and lactoferrin. One of the latest discoveries is the ability of some dinucleotides to facilitate the paracellular way on the cornea, therefore allowing the delivery of compounds, such as antiglaucomatous ones, more easily within the eye. The compound Ap4A has been described being abnormally elevated in patient's tears suffering of dry eye, Sjogren syndrome, congenital aniridia, or after refractive surgery, suggesting this molecule as biomarker for dry eye condition. At the intraocular level, some diadenosine polyphosphates are abnormally elevated in glaucoma patients, and this can be related to the stimulation of a P2Y2 receptor that increases the chloride efflux and water movement in the ciliary epithelium. In the retina, the dinucleotide dCp4U, has been proven to be useful to help in the recovery of retinal detachments. Altogether, dinucleoside polyphosphates are a group of compounds which present relevant physiological actions but which also can perform promising therapeutic benefits.
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Affiliation(s)
- Gonzalo Carracedo
- Department of Optics II (Optometry and Vision), Faculty of Optics and Optometry, Universidad Complutense de Madrid, Madrid, Spain
| | - Almudena Crooke
- Department of Biochemistry and Molecular Biology IV, Faculty of Optics and Optometry, Universidad Complutense de Madrid, Madrid, Spain
| | - Ana Guzman-Aranguez
- Department of Biochemistry and Molecular Biology IV, Faculty of Optics and Optometry, Universidad Complutense de Madrid, Madrid, Spain
| | - Maria J Pérez de Lara
- Department of Biochemistry and Molecular Biology IV, Faculty of Optics and Optometry, Universidad Complutense de Madrid, Madrid, Spain
| | - Alba Martin-Gil
- Department of Biochemistry and Molecular Biology IV, Faculty of Optics and Optometry, Universidad Complutense de Madrid, Madrid, Spain
| | - Jesús Pintor
- Department of Biochemistry and Molecular Biology IV, Faculty of Optics and Optometry, Universidad Complutense de Madrid, Madrid, Spain.
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Loma P, Guzman-Aranguez A, Perez de Lara MJ, Pintor J. Lactoferrin Levels in Tears are Increased by the Topical Application of Diadenosine Tetraphosphate. Curr Eye Res 2016; 41:1150-2. [PMID: 26863584 DOI: 10.3109/02713683.2015.1113431] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PURPOSE This study was undertaken to determine the effect of the topical application of diadenosine tetraphosphate on lactoferrin levels in rabbit tears. METHODS Diadenosine tetraphosphate was topically instilled in a single-dose, tear samples were collected by micropipette and lactoferrin was measured by Enzyme-Linked ImmunoSorbent Assay (ELISA). RESULTS The concentration of lactoferrin in rabbit tears was significantly increased 1 h after diadenosine tetraphosphate application, remaining elevated for 3 h more. This effect was blocked by P2 receptors antagonists. CONCLUSIONS Topical application of diadenosine tetraphosphate stimulates the secretion of lactoferrin in rabbit tears through P2 receptor activation.
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Affiliation(s)
- Patricia Loma
- a Departamento de Bioquímica y Biología Molecular , E.U. Óptica, Universidad Complutense de Madrid , Madrid , Spain
| | - Ana Guzman-Aranguez
- a Departamento de Bioquímica y Biología Molecular , E.U. Óptica, Universidad Complutense de Madrid , Madrid , Spain
| | - Maria J Perez de Lara
- a Departamento de Bioquímica y Biología Molecular , E.U. Óptica, Universidad Complutense de Madrid , Madrid , Spain
| | - Jesus Pintor
- a Departamento de Bioquímica y Biología Molecular , E.U. Óptica, Universidad Complutense de Madrid , Madrid , Spain
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Byun YS, Yoo YS, Kwon JY, Joo JS, Lim SA, Whang WJ, Mok JW, Choi JS, Joo CK. Diquafosol promotes corneal epithelial healing via intracellular calcium-mediated ERK activation. Exp Eye Res 2015; 143:89-97. [PMID: 26505315 DOI: 10.1016/j.exer.2015.10.013] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 10/15/2015] [Accepted: 10/16/2015] [Indexed: 12/27/2022]
Abstract
Diquafosol is known as a purinergic P2Y2 receptor (P2Y2R) agonist that stimulates water and mucin secretion from conjunctival epithelial cells and goblet cells, leading to tear film stability in dry eye. However, its effect on corneal epithelial healing has not yet been elucidated. The aim of the present study was to evaluate the effect of diquafosol on corneal epithelial healing in vivo and on P2Y2R-related downstream signaling pathways in vitro. We administered 3% diquafosol ophthalmic solution on 3 mm-diameter epithelial defects made in rat corneas and assessed the wound closure over time. Corneal epithelial healing was significantly accelerated in diquafosol-treated eyes compared to control eyes at 12 and 24 h. During wound healing, P2Y2R staining appeared stronger in the re-epithelized margin near the wound defect. To evaluate whether diquafosol stimulates epidermal growth factor receptor/extracellular-signal-regulated kinase (EGFR/ERK)-related cell proliferation and migration, simian virus 40-transfected human corneal epithelial (THCE) cells were used for in vitro experiments. Cell proliferation was accelerated by diquafosol at concentrations from 20 to 200 μM during 48 h, but inhibited at concentrations over 2000 μM. The intracellular calcium ([Ca(2+)]i) elevation was measured in diquafosol (100 μM)-stimulated cells using Fluo-4/AM ([Ca(2+)]i indicator). [Ca(2+)]i elevation was observed in diquafosol-stimulated cells regardless of the presence of calcium in media, and suramin pretreatment inhibited the calcium response. The effect of diquafosol on phosphorylation of EGFR, ERK and Akt, and cell migration was determined by western blotting and in vitro cell migration assay. Diquafosol induced phosphorylation of EGFR at 2 min post-stimulation, and phosphorylation of ERK at 5 min post-stimulation. Phosphorylation of ERK was attenuated in cells pretreated with suramin or BAPTA/AM ([Ca(2+)]i chelator), and partially with AG1478 (EGFR inhibitor). Likewise, diquafosol-treated cells showed acceleration of gap closure in cell migration assay, which was inhibited by suramin, BAPTA/AM, AG1478, and U0126 (MEK inhibitor). These studies demonstrate that diquafosol is effective in promoting corneal epithelial wound healing and that this effect may result from ERK-stimulated cell proliferation and migration via P2Y2R-mediated [Ca(2+)]i elevation.
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Affiliation(s)
- Yong-Soo Byun
- Department of Ophthalmology and Visual Science, College of Medicine, Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea; Catholic Institute of Visual Science, Catholic University of Korea, Seoul, Republic of Korea
| | - Young-Sik Yoo
- Catholic Institute of Visual Science, Catholic University of Korea, Seoul, Republic of Korea
| | - Ji-Young Kwon
- Catholic Institute of Visual Science, Catholic University of Korea, Seoul, Republic of Korea
| | - Jong-Soo Joo
- Department of Ophthalmology and Visual Science, College of Medicine, Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea
| | - Sung-A Lim
- Department of Ophthalmology and Visual Science, College of Medicine, Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea
| | - Woong-Joo Whang
- Department of Ophthalmology and Visual Science, College of Medicine, Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea
| | - Jee-Won Mok
- Catholic Institute of Visual Science, Catholic University of Korea, Seoul, Republic of Korea
| | - Jun-Sub Choi
- Catholic Institute of Visual Science, Catholic University of Korea, Seoul, Republic of Korea
| | - Choun-Ki Joo
- Department of Ophthalmology and Visual Science, College of Medicine, Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea; Catholic Institute of Visual Science, Catholic University of Korea, Seoul, Republic of Korea.
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Peral A, Carracedo G, Pintor J. Diadenosine polyphosphates in the tears of aniridia patients. Acta Ophthalmol 2015; 93:e337-e342. [PMID: 25545014 DOI: 10.1111/aos.12626] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Accepted: 11/11/2014] [Indexed: 12/28/2022]
Abstract
PURPOSE To quantify diadenosine polyphosphate levels in tears of congenital aniridia patients to estimate the ocular surface changes associated with congenital aniridia compared to normal individuals. METHODS Fifteen patients diagnosed with congenital aniridia and a control group of forty volunteers were studied. Tears were collected to quantify the levels of diadenosine polyphosphates Ap4 A and Ap5 A by high-performance liquid chromatography (H.P.L.C). Break-up time (BUT), corneal staining, McMonnies questionnaire and the Schirmer I test were applied to both groups. RESULTS Dinucleotides in congenital aniridia patients were higher than in control subjects. For the congenital aniridia group, under 15 years old, the values were 0.77 ± 0.01 μm and 0.17 ± 0.02 μm for Ap4 A and Ap5 A, respectively. The group aged from 15 to 40 years old provided concentrations of 4.37 ± 0.97 μm and 0.46 ± 0.05 μm for Ap4 A and Ap5 A, the group over 40 gave concentrations of 11.17 ± 5.53 μm and 0.68 ± 0.17 μm for Ap4 A and Ap5 A. Dinucleotide concentrations increased with age, being statistically significant different among the three age groups (p < 0.05). Congenital aniridia patients showed a normal tear secretion and no dry eye McMonnies scores, except for the group over 40 years old. BUT values decreased and corneal staining increased with age and correlated with the levels of diadenosine polyphosphates (p < 0.05). CONCLUSIONS The levels of dinucleotides in tears increase in aniridia patients compared with healthy subjects, and they seem to be related with the progression of corneal disorders in aniridia patients, both of which increase with ageing.
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Affiliation(s)
- Assumpta Peral
- Department of Optics II (Optometry & Vision); Faculty of Optics and Optometry; University Complutense of Madrid; Madrid Spain
| | - Gonzalo Carracedo
- Department of Optics II (Optometry & Vision); Faculty of Optics and Optometry; University Complutense of Madrid; Madrid Spain
| | - Jesús Pintor
- Department of Biochemistry and Molecular Biology IV; Faculty of Optics and Optometry; University Complutense of Madrid; Madrid Spain
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Hirata H, Sokabe M. A novel role of actomyosin bundles in ERK signaling. Commun Integr Biol 2015; 8:e1017176. [PMID: 26479219 PMCID: PMC4594555 DOI: 10.1080/19420889.2015.1017176] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 01/19/2015] [Indexed: 01/15/2023] Open
Abstract
Intracellular and extracellular mechanical environments have a significant impact on survival and proliferation of cells. While the extracellular signal-regulated kinase (ERK) subfamily of MAP kinases plays critical roles in regulations of these cellular behaviors, activation of ERK is affected by mechanical conditions of cells. We have recently found that ERK is activated on contractile actomyosin bundles. ERK activation on actomyosin bundles depends on tension in the bundles, which is generated by either myosin II activity of external forces. In this Addendum, we discuss a novel, potential role of actomyosin bundles in ERK signaling and mechanical regulation of cell survival and proliferation.
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Affiliation(s)
- Hiroaki Hirata
- Mechanobiology Institute; National University of Singapore ; Singapore
| | - Masahiro Sokabe
- Mechanobiology Institute; National University of Singapore ; Singapore ; Mechanobiology Laboratory; Nagoya University Graduate School of Medicine ; Nagoya, Japan
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15
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Loma P, Guzman-Aranguez A, Perez de Lara MJ, Pintor J. Diadenosine tetraphosphate improves adrenergic anti-glaucomatous drug delivery and efficiency. Exp Eye Res 2015; 134:141-7. [PMID: 25701803 DOI: 10.1016/j.exer.2015.02.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 01/28/2015] [Accepted: 02/17/2015] [Indexed: 01/24/2023]
Abstract
The effect of the dinucleotide P(1), P(4)-Di (adenosine-5') tetraphosphate (Ap4A) in improving adrenergic anti-glaucomatous delivery by modifying the tight junction proteins of the corneal epithelium was evaluated. Stratified human corneal epithelial cells (HCLE) were treated with Ap4A (100 μM) for 5 min and TJ protein levels and barrier function were analysed by western blotting and transepithelial electrical resistance (TEER), respectively. Western blot experiments showed a significant reduction at 2 h (45% reduction of ZO-1 and 65% reduction of occludin protein levels) as compared to non-treated (control) cells. Two hours after Ap4A treatment, TEER values were significantly reduced (65% as compared to control levels (p < 0.001)), indicating an increase in corneal barrier permeability. Topical application of Ap4A in New Zealand white rabbits two hours before the instillation of the hypotensor compounds (the α2-adrenergic receptor agonist, brimonidine and the β-adrenergic receptor antagonist, timolol), improved the delivery of these compounds to the anterior chamber as well as their hypotensive action on the intraocular pressure. The results obtained showed that, when Ap4A was topically applied two hours before the adrenergic compounds, the concentration of brimonidine in the aqueous humour increased from 64.3 ± 5.3 nM to 240.6 ± 8.6 nM and from 58.9 ± 9.2 nM to 183.7 ± 6.8 nM in the case of timolol, which also produces a more profound effect on IOP. Therefore, Ap4A treatment results in a better entrance of adrenergic anti-glaucomatous compounds within the eye and consequently improved therapeutic efficiency by increasing corneal epithelial barrier permeability.
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Affiliation(s)
- Patricia Loma
- Department of Biochemistry and Molecular Biology IV, Faculty of Optics and Optometry, Universidad Complutense de Madrid, Spain
| | - Ana Guzman-Aranguez
- Department of Biochemistry and Molecular Biology IV, Faculty of Optics and Optometry, Universidad Complutense de Madrid, Spain
| | - Maria Jesus Perez de Lara
- Department of Biochemistry and Molecular Biology IV, Faculty of Optics and Optometry, Universidad Complutense de Madrid, Spain
| | - Jesus Pintor
- Department of Biochemistry and Molecular Biology IV, Faculty of Optics and Optometry, Universidad Complutense de Madrid, Spain.
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16
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Loma P, Guzman-Aranguez A, Pérez de Lara MJ, Pintor J. Diadenosine tetraphosphate induces tight junction disassembly thus increasing corneal epithelial permeability. Br J Pharmacol 2014; 172:1045-58. [PMID: 25297531 DOI: 10.1111/bph.12972] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Revised: 09/26/2014] [Accepted: 09/29/2014] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND AND PURPOSE Here, we have studied the effects of the dinucleotide P(1), P(4)-Di (adenosine-5') tetraphosphate (Ap4 A) on corneal barrier function conferred by the tight junction (TJ) proteins and its possible involvement in ocular drug delivery and therapeutic efficiency. EXPERIMENTAL APPROACH Experiments in vitro were performed using human corneal epithelial cells (HCLEs) treated with Ap4 A (100 μM) for 5 min. Western blot analysis and transepithelial electrical resistance (TEER) were performed to study the TJ protein levels and barrier function respectively. Intracellular pathways involved were determined using an ERK inhibitor and P2Y(2) receptor siRNAs. In in vivo assays with New Zealand rabbits, TJ integrity was examined by zonula occludens-1 (ZO-1) staining. The hypotensive compound 5-methoxycarbonylamino-N-acetyltryptamine (5-MCA-NAT) was used to assess improved delivery, measuring its levels by HPLC and measuring intraocular pressure using 5-MCA-NAT, P2Y receptor antagonists and P2Y2 siRNAs. KEY RESULTS Two hours after Ap4 A pretreatment, TJ protein levels in HCLE cells were reduced around 40% compared with control. TEER values were significantly reduced at 2 and 4 h (68 and 52% respectively). TJ reduction and ERK activation were blocked by the ERK inhibitor U012 and P2Y(2) siRNAs. In vivo, topical application of Ap4 A disrupted ZO-1 membrane distribution. 5-MCA-NAT levels in the aqueous humour were higher when Ap4 A was previously instilled and its hypotensive effect was also increased. This action was reversed by P2Y receptor antagonists and P2Y(2) siRNA. CONCLUSIONS AND IMPLICATIONS Ap4 A increased corneal epithelial barrier permeability. Its application could improve ocular drug delivery and consequently therapeutic efficiency.
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Affiliation(s)
- P Loma
- Department of Biochemistry and Molecular Biology IV, Faculty of Optics and Optometry, Universidad Complutense de Madrid, Spain
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Diadenosine tetraphosphate contributes to carbachol-induced tear secretion. Purinergic Signal 2014; 11:87-93. [PMID: 25398705 DOI: 10.1007/s11302-014-9434-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 11/06/2014] [Indexed: 10/24/2022] Open
Abstract
The purpose of this study is to investigate if the cholinergic stimulation by carbachol on tear secretion is a direct process or if it is also mediated by purinergic mechanisms. Experiments were performed in New Zealand male rabbits. The amount of tear secretion was measured with Schirmer's test and then analyzed by a HPLC protocol in order to study the nucleotide levels. Animal eyes were instilled with carbachol (a cholinergic agonist), pirenzepine, gallamine and 4-DAMP (muscarinic antagonists), PPADS, suramin and reactive blue 2 (purinergic antagonists), and a P2Y2 receptor small interfering RNA (siRNA). Tear secretion increased with the instillation of carbachol, approximately 84 % over control values 20 min after the instillation and so did Ap4A and ATP release. When we applied carbachol in the presence of muscarinic antagonists, tear volume only increased to 4 % with atropine, 12 % in the case of pirenzepine, 3 % with gallamine, and 8 % with 4-DAMP. In the presence of carbachol and purinergic antagonists, tear secretion was increased to 12 % (all values compared to basal tear secretion). By analyzing tear secretion induced with carbachol in presence of a P2Y2 receptor siRNA, we found that tear secretion was diminished to 60 %. The inhibition of tear secretion in the presence of carbachol and purinergic antagonists or P2Y2 siRNA occurred with no apparent change in the tear amount of Ap4A. These experiments demonstrated the participation of Ap4A in lacrimal secretion process.
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Wright M, Azhar MA, Kamal A, Miller AD. Syntheses of stable, synthetic diadenosine polyphosphate analogues using recombinant histidine-tagged lysyl tRNA synthetase (LysU). Bioorg Med Chem Lett 2014; 24:2346-52. [PMID: 24736113 DOI: 10.1016/j.bmcl.2014.03.064] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2014] [Revised: 03/18/2014] [Accepted: 03/20/2014] [Indexed: 11/18/2022]
Abstract
Recombinant Escherichia coli lysyl-tRNA synthase (LysU) has been previously utilised in the production of stabile, synthetic diadenosine polyphosphate (ApnA) analogues. Here we report on the extended use of a new recombinant histidine residue-tagged LysU as a tool for highly controlled phosphatephosphate bond formation between nucleotides, avoiding the need for complex protecting group chemistries. Resulting high yielding tandem LysU-based biosynthetic-synthetic/synthetic-biosynthetic strategies emerge for the preparation of varieties of ApnA analogues directly from inexpensive natural nucleotides and nucleosides. Analogues so formed make a useful small library with which to probe ApnA activities in vitro and in vivo leading to the discovery of new, potentially potent biopharmaceuticals active against chronic pain and other chronic, high-burden disease states.
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Affiliation(s)
- Michael Wright
- Imperial College Genetic Therapies Centre, Department of Chemistry, Imperial College London, Flowers Building, Armstrong Road, London SW7 2AZ, UK; Institute of Pharmaceutical Science, King's College London, Franklin-Wilkins Building, Waterloo Campus, 150 Stamford Street, London SE1 9NH, UK
| | - M Ameruddin Azhar
- Imperial College Genetic Therapies Centre, Department of Chemistry, Imperial College London, Flowers Building, Armstrong Road, London SW7 2AZ, UK; Organic-I Division, Indian Institute of Chemical Technology, Habsigida, Hyderabad, India
| | - Ahmed Kamal
- Organic-I Division, Indian Institute of Chemical Technology, Habsigida, Hyderabad, India
| | - Andrew D Miller
- Imperial College Genetic Therapies Centre, Department of Chemistry, Imperial College London, Flowers Building, Armstrong Road, London SW7 2AZ, UK; Institute of Pharmaceutical Science, King's College London, Franklin-Wilkins Building, Waterloo Campus, 150 Stamford Street, London SE1 9NH, UK.
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Carracedo G, Cacho I, Sanchez-Naves J, Pintor J. Diadenosine polyphosphates after laser in situ keratomileusis and photorefractive keratectomy refractive techniques. Acta Ophthalmol 2014; 92:e5-e11. [PMID: 23901874 DOI: 10.1111/aos.12194] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE To study the concentrations of diadenosine polyphosphates in the ocular surface after PRK and LASIK. METHODS Sixty-one patients (30 males and 31 females) with ages ranging from 20 to 63 (34.04 ± 9.13 years) were recruited in Balear Institute of Ophthalmology, Palma de Mallorca, Spain. LASIK was performed in 92 eyes of 46 patients and PRK in 25 eyes of 15 patients. Variations in the levels of diadenosine polyphosphate (Ap4 A and Ap5 A), Schirmer I (Jones test), TBUT, corneal staining together with the Dry Eye Questionnaire to evaluate discomfort and dryness were studied. All tests were performed at the preoperative visit and at 1-day, 2-week, 1-month and 3-month postoperative visits. RESULTS Ap4 A showed a 5 and 3.5 fold increase at the 1-day visit for LASIK and PRK, respectively. LASIK patients continued having higher statistically significant concentrations (p = 0.01) all over the follow-up. Ap5 A showed no significant differences at any visit. Tear volume decreased during the 3 months in LASIK. The PRK cases had a normal volume at 1 month. TBUT in LASIK increased at the 1-day visit (p = 0,002) and decreased from the 2 weeks onwards and for the PRK, decreased by a 35% at the 1-day visit and kept reduced for a month. Discomfort only increased at the 1-day visit (p = 0.007). Dryness frequency was similar in all visits. CONCLUSIONS Ap4 A levels only are increased in refractive surgery patients during the first day after the surgery. This increasing suggests that Ap4 A may help accelerating the healing process.
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Affiliation(s)
- Gonzalo Carracedo
- Department of Optics II (Optometry and Vision), Faculty of Optics, Universidad Complutense de Madrid, Madrid, SpainInstituto Balear de Oftalmología, Palma de Mallorca, SpainDepartment of Biochemistry and Molecular Biology IV, Faculty of Optics, Universidad Complutense de Madrid, Madrid, Spain
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Iwatsuka K, Iwamoto H, Kinoshita M, Inada K, Yasueda SI, Kakehi K. Comparative Studies ofN-Glycans and Glycosaminoglycans Present in SIRC (Statens Seruminstitut Rabbit Cornea) Cells and Corneal Epithelial Cells from Rabbit Eyes. Curr Eye Res 2014; 39:686-94. [DOI: 10.3109/02713683.2013.863940] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Pothula S, Bazan HEP, Chandrasekher G. Regulation of Cdc42 expression and signaling is critical for promoting corneal epithelial wound healing. Invest Ophthalmol Vis Sci 2013; 54:5343-52. [PMID: 23833064 DOI: 10.1167/iovs.13-11955] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
PURPOSE Cdc42, a member of Rho GTPases (guanosine triphosphatases), participates in cytokine- and growth factor-controlled biological functions in mammalian tissues. Here, we examined Cdc42 role in corneal epithelial wound healing and the influence of hepatocyte, keratinocyte, and epidermal growth factor (HGF, KGF, and EGF)-mediated signaling on Cdc42. METHODS Epithelial wounds were created on the corneas of live rabbits by complete debridement and in rabbit corneal epithelial primary cultures through scratch injury. Cdc42 expression in cultures was suppressed using Cdc42 siRNA. Cdc42 activation was determined by pull-down assays with PAK-agarose beads. Cdc42 expression was analyzed by immunoblotting and immunofluorescence. Association of Cdc42 with cell-cycle proteins was identified by immunoprecipitation. RESULTS In rabbit corneas, significant increase in Cdc42 expression that occurred 2 to 4 days after the injury coincided with wound closure, and by 8 days the expression reached near basal levels. Silencing of Cdc42 expression in cultures caused inhibition of wound closure as a result of 60% to 75% decrease in epithelial migration and growth. HGF, KGF, and EGF increased Cdc2 expression, activation, and its phosphorylation on ser71. Inhibition of growth factor-mediated PI-3K signaling resulted in the downregulation of Cdc42 expression and its phosphorylation. Increased association of cell-cycle proteins p27(kip) and cyclin-dependent kinase 4 (CDK4) with Cdc42; and phosphorylated Cdc42 with plasma membrane leading edges was also observed in the presence of growth factors. CONCLUSIONS Cdc42 is an important regulator of corneal epithelial wound repair. To promote healing, Cdc42 may interact with receptor tyrosine kinase-activated signaling cascades that participate in cell migration and cell-cycle progression.
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Affiliation(s)
- Swetha Pothula
- Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Brookings, South Dakota 57007, USA
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Carracedo G, Guzman-Aranguez A, Loma P, Pintor J. Diadenosine polyphosphates release by human corneal epithelium. Exp Eye Res 2013; 113:156-61. [PMID: 23791635 DOI: 10.1016/j.exer.2013.05.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 05/16/2013] [Accepted: 05/30/2013] [Indexed: 01/11/2023]
Abstract
Diadenosine polyphosphates are a type of dinucleotides that have been detected in rabbit and human tears. However, their origin and their mechanism of release have not been fully elucidated. In this work we investigated whether the dinucleotides Ap4A and Ap5A can be released from human corneal epithelia as a consequence of shear stress stimuli. In in vitro experiments, concentrations of Ap4A and Ap5A before mechanical stimulus of stratified human corneal epithelial cells were 3.18 ± 0.43 nM and 0.81 ± 0.13 nM, respectively. After shear stimulation, concentrations significantly increased to 12.01 ± 2.19 nM for Ap4A and 2.83 ± 0.41 nM for Ap5A. No significant differences in lactate dehydrogenase activity were detected between non-stimulated stratified human corneal epithelial cells and cells exposed to mechanical shear-stress, indicating that the rise of dinucleotide levels was not due to cell lysis. In in vivo experiments, individuals subjected to a rise in blinking frequency showed a significant increase of Ap4A (∼25-fold when experiment was performed without anaesthetic and 75-fold with anaesthetic) and Ap5A concentration in tears (∼50-fold when experiment was performed without anaesthetic and 125-fold with anaesthetic). Shear-stress stimuli induces Ap4A and Ap5A release from human corneal epithelium, thus explaining the origin of these relevant compounds for the ocular surface biochemistry and physiology.
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Affiliation(s)
- Gonzalo Carracedo
- Department of Optics II (Optometry and Vision), Faculty of Optics and Optometry, Universidad Complutense de Madrid, Madrid, Spain.
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Guzman-Aranguez A, Santano C, Martin-Gil A, Fonseca B, Pintor J. Nucleotides in the eye: focus on functional aspects and therapeutic perspectives. J Pharmacol Exp Ther 2013; 345:331-41. [PMID: 23504005 DOI: 10.1124/jpet.112.202473] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The presence and activity of nucleotides and dinucleotides in the physiology of most, if not all, organisms, from bacteria to humans, have been recognized by the scientific community, and the eye is no exception. Nucleotides in the dynamic fluids interact with many ocular structures, such as the tears and aqueous humor. Moreover, high concentrations of nucleotides in these secretions may reflect disease states such as dry eye and glaucoma. Apart from the nucleotide concentration in these fluids, P2 purinergic receptors have been described on the ocular surface (cornea and conjunctiva), anterior pole (ciliary body, trabecular meshwork), and posterior pole (retina). P2X and P2Y purinergic receptors are essential in maintaining the homeostasis of ocular processes, such as tear secretion, aqueous humor production, or retinal modulation. When they are functioning properly, they allow the eye to do its job (to see), but in some cases, a lack or an excess of nucleotides or a malfunction in the corresponding purinergic receptors leads to disease. This Perspective is focused on the nucleotides and dinucleotides and the P2 purinergic receptors in the eye and how they contribute to normal and disease states. We also emphasize the action of nucleotides and their receptors and antagonists as potential therapeutic agents.
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Affiliation(s)
- Ana Guzman-Aranguez
- Department of Biochemistry and Molecular Biology, Faculty of Optics and Optometry, Universidad Complutense Madrid, C/Arcos de Jalón 118, 28037 Madrid, Spain
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Guzman-Aranguez A, Díez LM, Martín-Gil A, Gualix J, Miras-Portugal MT, Pintor J. Effect of diinosine polyphosphates on intraocular pressure in normotensive rabbits. Exp Eye Res 2012; 101:49-55. [PMID: 22677090 DOI: 10.1016/j.exer.2012.05.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Revised: 04/27/2012] [Accepted: 05/29/2012] [Indexed: 12/01/2022]
Abstract
The ability of diinosine polyphosphates, diinosine triphosphate (Ip(3)I), diinosine tetraphosphate (Ip(4)I) and diinosine pentaphosphate (Ip(5)I) to modify intraocular pressure in normotensive New Zealand white rabbits was tested. Ip(5)I produced increase in intraocular pressure, while Ip(3)I and Ip(4)I produced a decrease. Ip(4)I was the most effective reducing intraocular pressure inducing a maximal decrease of intraocular pressure to 74.2 ± 2.5% compared with the control value. Dose-response analysis demonstrated a concentration dependent pattern which presented a pD(2) value of 6.19 ± 0.18, equivalent to an EC(50) of 0.63 μM. Regarding the underlying mechanism used by Ip(4)I to reduce intraocular pressure, studies with agonists and antagonists revealed that Ip(4)I reduces intraocular pressure via P2Y receptors in the eye. We suggest that topical application of Ip(4)I to the cornea has therapeutic potential for lowering intraocular pressure, a major risk factor for glaucoma.
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Affiliation(s)
- Ana Guzman-Aranguez
- Dep. Bioquímica y Biología Molecular, Escuela Universitaria de Óptica, Universidad Complutense de Madrid, Spain
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Ziganshina AP, Ziganshin BA, Ziganshin AU. Dual effects of ATP on isolated arteries of the bovine eye. Pharmacol Res 2012; 66:170-6. [PMID: 22521505 DOI: 10.1016/j.phrs.2012.04.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Revised: 04/03/2012] [Accepted: 04/03/2012] [Indexed: 01/22/2023]
Abstract
Although the presence of purinoreceptors has been shown in many human and animal arteries, there is few data yet about their role in the arteries of the eye. The purpose of the present study was to evaluate the effects of several agonists of purinoreceptors on isolated arteries of the bovine eye. Responses of isolated preparations of bovine ophthalmic (OA) and posterior ciliary arteries (PCA) to agonists of purinoreceptors (ATP, α,β-methylene-ATP-α,β-meATP, 2-methylthioATP-2meSATP, uridine-5'-triphosphate-UTP) as well as agonists of adreno-, cholino-, adenosine and histamine receptors were recorded by a standard organ bath method. ATP induced contractions of the intact vessels but caused relaxation of α,β-meATP-pretreated arteries. Contractile responses of PCA to high concentrations of ATP and α,β-meATP were significantly stronger than responses of OA, as well as relaxative responses to ATP and adenosine were significantly stronger in PCA than in OA. We suggest that there are several subtypes of functionally active purinoreceptors in both OA and PCA, although the potency of agonists of purinoreceptors to produce mechanical responses is higher in PCA than in OA. Purinoreceptors can be potential targets for new drugs, treating vascular pathology of the eye.
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Affiliation(s)
- Anna P Ziganshina
- Kazan State Medical University, 49 Butlerov Str., Kazan 420012, Russia
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Mediero A, Crooke A, Guzmán-Aránguez A, Pintor J. Phospholipase C/Protein Kinase C pathway is essential for corneal re-epithelialization induced by Ap(4)A. Curr Eye Res 2011; 36:1108-15. [PMID: 21988553 DOI: 10.3109/02713683.2011.614371] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PURPOSE We have previously demonstrated the importance of P2Y(2) receptors in the corneal re-epithelialization effect triggered by diadenosine tetraphosphate (Ap(4)A). In addition, we have also shown the ERK1/2 and ROCK-I activation in Ap(4)A-wound repair response. Phospholipase C/Protein Kinase C (PLC/PKC) pathway activation has been suggested as a molecular mechanism of growth factors-modulated corneal cell migration and P2Y(2) agonists. Hence, the aim of this study is to investigate the role of PLC/PKC cascade in the modification of re-epithelialization rate triggered by Ap(4)A in an established corneal epithelial cell line (Statens Seruminstitut rabbit cornea [SIRC] cells). METHODS In wounded confluent SIRC cell monolayers and in the presence or absence of Ap(4)A 100 μM, a group of PLC/PKC inhibitors (U73122 3 μM, Staurosporine 1 nM and Bisindolylmaleimide-I 10 μM) and activator (PDBU 1 μM) were assayed and the migration rate was evaluated. Also, the activation of ERK1/2 and ROCK-I was examined by Western blot assay after treatment with or without Ap(4)A, U73122, Staurosporine, Bisindolylmaleimide-I and PDBU. RESULTS Pre-treatment of wounded SIRC cells with PLC/PKC inhibitors significantly diminished the Ap(4)A-stimulated cell migration rate. Furthermore, PLC/PKC inhibitors also reduced ERK1/2 phosphorylation and ROCK-I activation triggered by Ap(4)A. CONCLUSIONS The present study shows the involvement of PLC/PKC pathway in the activation of ERK1/2 and ROCK-I downstream signal transduction pathways stimulated by Ap(4)A/P2Y(2) receptor during corneal epithelial wound repair.
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Affiliation(s)
- Aránzazu Mediero
- Departamento de Bioquímica, EU Óptica, Universidad Complutense de Madrid, Madrid, Spain
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Chaturvedi LS, Marsh HM, Basson MD. Role of RhoA and its effectors ROCK and mDia1 in the modulation of deformation-induced FAK, ERK, p38, and MLC motogenic signals in human Caco-2 intestinal epithelial cells. Am J Physiol Cell Physiol 2011; 301:C1224-38. [PMID: 21849669 DOI: 10.1152/ajpcell.00518.2010] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Repetitive deformation enhances intestinal epithelial migration across tissue fibronectin. We evaluated the contribution of RhoA and its effectors Rho-associated kinase (ROK/ROCK) and mammalian diaphanous formins (mDia1) to deformation-induced intestinal epithelial motility across fibronectin and the responsible focal adhesion kinase (FAK), extracellular signal-regulated kinase (ERK), p38, and myosin light chain (MLC) signaling. We reduced RhoA, ROCK1, ROCK2, and mDia1 by smart-pool double-stranded short-interfering RNAs (siRNA) and pharmacologically inhibited RhoA, ROCK, and FAK in human Caco-2 intestinal epithelial monolayers on fibronectin-coated membranes subjected to 10% repetitive deformation at 10 cycles/min. Migration was measured by wound closure. Stimulation of migration by deformation was prevented by exoenzyme C3, Y27632, or selective RhoA, ROCK1, and ROCK2 or mDia1 siRNAs. RhoA, ROCK inhibition, or RhoA, ROCK1, ROCK2, mDia1, and FAK reduction by siRNA blocked deformation-induced nuclear ERK phosphorylation without preventing ERK phosphorylation in the cytoplasmic protein fraction. Furthermore, RhoA, ROCK inhibition or RhoA, ROCK1, ROCK2, and mDia1 reduction by siRNA also blocked strain-induced FAK-Tyr(925), p38, and MLC phosphorylation. These results suggest that RhoA, ROCK, mDia1, FAK, ERK, p38, and MLC all mediate the stimulation of intestinal epithelial migration by repetitive deformation. This pathway may be an important target for interventions to promote mechanotransduced mucosal healing during inflammation.
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Glaucoma patients present increased levels of diadenosine tetraphosphate, Ap(4)A, in the aqueous humour. Exp Eye Res 2010; 92:221-6. [PMID: 21147104 DOI: 10.1016/j.exer.2010.12.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Revised: 11/28/2010] [Accepted: 12/02/2010] [Indexed: 11/23/2022]
Abstract
Previous studies have shown the presence of diadenosine tetraphosphate (Ap(4)A) and pentaphosphate (Ap(5)A) in the aqueous humour (AH) of different species. When topically applied to the rabbit cornea, Ap(4)A decreased IOP while Ap(5)A increased it. Here we study the presence of dinucleoside polyphosphates in the AH from human patients with or without glaucoma. AH was obtained at the time of cataract surgery from patients with (n=16) or without (n=10) primary open-angle glaucoma. AH (0.1-0.2 ml) was collected at the beginning of surgery through a corneal paracentesis and immediately cooled in liquid nitrogen, kept frozen and protected from light. AH aliquots were analyzed by HPLC for the presence of Ap(4)A and Ap(5)A. Both, Ap(4)A and Ap(5)A were detected in the AH of both experimental groups. No significant differences were found for Ap(5)A. In contrast, Ap(4)A levels were increased by ∼15-fold in the AH from glaucomatous eyes ranging from 19.5±9.2 nM in normal individuals to 286.03±30.9 nM in glaucomatous patients. In conclusion, both Ap(4)A and Ap(5)A were detected for the first time in human AH. Interestingly, glaucomatous eyes presented elevated concentrations of Ap(4)A compared to controls. The role of Ap(4)A needs to be elucidated but it may help to protect the autonomic innervation in the ciliary body/trabecular meshwork. Also, because of its higher levels in glaucoma patients it may be considered as a possible glaucoma biomarker.
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Hoyle CHV, Pintor JJ. Diadenosine tetraphosphate protects sympathetic terminals from 6-hydroxydopamine-induced degeneration in the eye. Acta Physiol (Oxf) 2010; 199:205-10. [PMID: 20121713 DOI: 10.1111/j.1748-1716.2010.02089.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIMS To examine diadenosine tetraphosphate (Ap(4)A) for its ability to protect the eye from neurodegeneration induced by subconjunctival application of 6-hydroxydopamine (6-OHDA). METHODS Intraocular neurodegeneration of anterior structures was induced by subconjunctival injections of 6-OHDA. Animals were pre-treated with topical corneal applications of Ap(4)A or saline. RESULTS 6-OHDA caused miosis, abnormal pupillary light reflexes, a precipitous drop in intraocular pressure and loss of VMAT2-labelled (vesicle monoamine transporter-2, a marker for sympathetic neurones) intraocular neurones. Pre-treatment with Ap(4)A prevented all of these changes from being induced by 6-OHDA, demonstrably preserving the sympathetic innervation of the ciliary processes. This neuroprotective action of Ap(4)A was not shared with the related compounds adenosine, ATP or diadenosine pentaphosphate. P2-receptor antagonists showed that the effects of Ap(4)A were mediated via a P2-receptor. CONCLUSION Ap4A is a natural component of tears and aqueous humour, and its neuroprotective effect indicates that one of its physiological roles is to maintain neurones within the eye. Ap(4)A can prevent the degeneration of intraocular nerves, and it is suggested that this compound may provide the basis for a therapeutic intervention aimed at preventing or ameliorating the development of glaucoma associated with neurodegenerative diseases. Furthermore, subconjunctival application of 6-OHDA provides a useful model for studying diseases that cause ocular sympathetic dysautonomia.
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Affiliation(s)
- C H V Hoyle
- Dep. Bioquímica, Escuela Universitaria de Optica, Universidad Complutense de Madrid, Madrid, Spain
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