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Zhang C, Tannous E, Thomas A, Jung N, Ma E, Zheng JJ. Dexamethasone Modulates the Dynamics of Wnt Signaling in Human Trabecular Meshwork Cells. Vision (Basel) 2023; 7:43. [PMID: 37368816 DOI: 10.3390/vision7020043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 05/09/2023] [Accepted: 05/21/2023] [Indexed: 06/29/2023] Open
Abstract
Trabecular meshwork (TM) tissue is highly specialized, and its structural integrity is crucial for maintaining homeostatic intraocular pressure (IOP). The administration of glucocorticoids, such as dexamethasone (DEX), can perturb the TM structure and significantly increase IOP in susceptible individuals, resulting in ocular diseases such as steroid-induced glaucoma, a form of open-angle glaucoma. Although the exact mechanism involved in steroid-induced glaucoma remains elusive, increasing evidence suggests that DEX may act through various signaling cascades in TM cells. Despite uncertainty surrounding the specific process by which steroid-induced glaucoma occurs, there is growing evidence to indicate that DEX can impact multiple signaling pathways within TM cells. In this study, we examined the impact of DEX treatment on the Wnt signaling pathway in TM cells, given that Wnt signaling has been reported to play a crucial role in regulating extracellular matrix (ECM) levels in the TM. To further elucidate the role of Wnt signaling in the glaucomatous phenotype, we examined mRNA expression patterns between Wnt signaling markers AXIN2 and sFRP1 and DEX-mediated induction of myocilin (MYOC) mRNA and protein levels over 10 days in DEX-treated primary TM cells. We observed a sequential pattern of peak expression between AXIN2, sFRP1, and MYOC. Based on the study, we propose that sFRP1 upregulation could be a result of a negative feedback mechanism generated by stressed TM cells to suppress abnormal Wnt signaling activities.
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Affiliation(s)
- Chi Zhang
- Stein Eye Institute, Department of Ophthalmology, David Geffen School of Medicine, The Molecular Biology Institute at the University of California, Los Angeles, CA 90095, USA
| | - Elizabeth Tannous
- Stein Eye Institute, Department of Ophthalmology, David Geffen School of Medicine, The Molecular Biology Institute at the University of California, Los Angeles, CA 90095, USA
| | - Alseena Thomas
- Stein Eye Institute, Department of Ophthalmology, David Geffen School of Medicine, The Molecular Biology Institute at the University of California, Los Angeles, CA 90095, USA
| | - Natalia Jung
- Stein Eye Institute, Department of Ophthalmology, David Geffen School of Medicine, The Molecular Biology Institute at the University of California, Los Angeles, CA 90095, USA
| | - Edmond Ma
- Stein Eye Institute, Department of Ophthalmology, David Geffen School of Medicine, The Molecular Biology Institute at the University of California, Los Angeles, CA 90095, USA
| | - Jie J Zheng
- Stein Eye Institute, Department of Ophthalmology, David Geffen School of Medicine, The Molecular Biology Institute at the University of California, Los Angeles, CA 90095, USA
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Detailed 3D micro-modeling of rat aqueous drainage channels based on two-photon imaging: simulating aqueous humor through trabecular meshwork and Schlemm’s canal by two-way fluid structure interaction approach. Med Biol Eng Comput 2022; 60:1915-1927. [DOI: 10.1007/s11517-022-02580-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 04/22/2022] [Indexed: 10/18/2022]
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Ko MK, Woo JI, Gonzalez JM, Kim G, Sakai L, Peti-Peterdi J, Kelber JA, Hong YK, Tan JC. Fibrillin-1 mutant mouse captures defining features of human primary open glaucoma including anomalous aqueous humor TGF beta-2. Sci Rep 2022; 12:10623. [PMID: 35739142 PMCID: PMC9226129 DOI: 10.1038/s41598-022-14062-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 05/31/2022] [Indexed: 11/09/2022] Open
Abstract
Primary open angle glaucoma (POAG) features an optic neuropathy, elevated aqueous humor (AH) TGFβ2, and major risk factors of central corneal thickness (CCT), increasing age and intraocular pressure (IOP). We examined Tight skin (Tsk) mice to see if mutation of fibrillin-1, a repository for latent TGFβ, is associated with characteristics of human POAG. We measured: CCT by ocular coherence tomography (OCT); IOP; retinal ganglion cell (RGC) and optic nerve axon counts by microscopic techniques; visual electrophysiologic scotopic threshold responses (STR) and pattern electroretinogram (PERG); and AH TGFβ2 levels and activity by ELISA and MINK epithelial cell-based assays respectively. Tsk mice had open anterior chamber angles and compared with age-matched wild type (WT) mice: 23% thinner CCT (p < 0.003); IOP that was higher (p < 0.0001), more asymmetric (p = 0.047), rose with age (p = 0.04) and had a POAG-like frequency distribution. Tsk mice also had RGCs that were fewer (p < 0.04), declined with age (p = 0.0003) and showed increased apoptosis and glial activity; fewer optic nerve axons (p = 0.02); abnormal axons and glia; reduced STR (p < 0.002) and PERG (p < 0.007) visual responses; and higher AH TGFβ2 levels (p = 0.0002) and activity (p = 1E-11) especially with age. Tsk mice showed defining features of POAG, implicating aberrant fibrillin-1 homeostasis as a pathogenic contributor to emergence of a POAG phenotype.
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Affiliation(s)
| | | | | | | | - Lynn Sakai
- Department of Medical and Molecular Genetics, Oregon Health Sciences University, Portland, OR, USA
| | - Janos Peti-Peterdi
- Departments of Physiology, Biophysics and Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Jonathan A Kelber
- Developmental Oncogene Laboratory, California State University Northridge, Northridge, CA, USA
| | - Young-Kwon Hong
- Department of Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - James C Tan
- Doheny Eye Institute, Los Angeles, CA, USA.
- Department of Ophthalmology, University of California Los Angeles, Los Angeles, CA, USA.
- Sightgene, Inc., 9227 Reseda Blvd, #182, Northridge, CA, 91324-3137, USA.
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Koudouna E, Young RD, Overby DR, Ueno M, Kinoshita S, Knupp C, Quantock AJ. Ultrastructural variability of the juxtacanalicular tissue along the inner wall of Schlemm's canal. Mol Vis 2019; 25:517-526. [PMID: 31588175 PMCID: PMC6776461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 09/19/2019] [Indexed: 11/16/2022] Open
Abstract
Purpose Increased resistance of aqueous humor drainage from the eye through Schlemm's canal (SC) is the basis for elevated intraocular pressure in glaucoma. Experimental evidence suggests that the bulk of outflow resistance lies in the vicinity of the inner wall endothelial lining of SC and the adjacent juxtacanalicular tissue (JCT). However, there is little understanding of how this resistance is generated, and a detailed understanding of the structure-function relationship of the outflow pathway has not been established yet. In the present study, regional variations in the ultrastructure of the JCT and the inner wall of SC were investigated in three dimensions. Methods With the use of serial block face scanning electron microscopy (SBF-SEM), the volume occupied by the electron lucent spaces of the JCT compared to that occupied by the cellular and extracellular matrix was investigated and quantified. The distribution of giant vacuoles (GVs) and pores in the inner wall endothelium of SC was further examined. Results With increasing distance from the inner wall of SC, the volume of the electron lucent spaces increased above 30%. In contrast, the volume of these spaces in immediate contact with the inner wall endothelium was minimal (<10%). Circumferential variability in the type and distribution of GVs was observed, and the percentage of GVs with pores varied between 3% and 27%. Conclusions These studies provide a detailed quantitative analysis of the ultrastructure of JCT and the distribution of GVs along the circumference of SC in three dimensions, supporting the non-uniform or segmental aqueous outflow.
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Affiliation(s)
- Elena Koudouna
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Wales, UK
| | - Robert D. Young
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Wales, UK
| | - Darryl R. Overby
- Department of Bioengineering, Imperial College London, London, UK
| | - Morio Ueno
- Department of Ophthalmology, Kyoto Prefectural University of Medicine, Hirokoji Kawaramachi, Kamigyo-ku, Kyoto, Japan
| | - Shigeru Kinoshita
- Department of Ophthalmology, Kyoto Prefectural University of Medicine, Hirokoji Kawaramachi, Kamigyo-ku, Kyoto, Japan
| | - Carlo Knupp
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Wales, UK
| | - Andrew J. Quantock
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Wales, UK
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Gonzalez JM, Ko MK, Hong YK, Weigert R, Tan JCH. Deep tissue analysis of distal aqueous drainage structures and contractile features. Sci Rep 2017; 7:17071. [PMID: 29213129 PMCID: PMC5719038 DOI: 10.1038/s41598-017-16897-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 11/15/2017] [Indexed: 01/04/2023] Open
Abstract
Outflow resistance in the aqueous drainage tract distal to trabecular meshwork is potentially an important determinant of intraocular pressure and success of trabecular bypass glaucoma surgeries. It is unclear how distal resistance is modulated. We sought to establish: (a) multimodal 2-photon deep tissue imaging and 3-dimensional analysis of the distal aqueous drainage tract (DT) in transgenic mice in vivo and ex vivo; (b) criteria for distinguishing the DT from blood and lymphatic vessels; and (c) presence of a DT wall organization capable of contractility. DT lumen appeared as scleral collagen second harmonic generation signal voids that could be traced back to Schlemm's canal. DT endothelium was Prox1-positive, CD31-positive and LYVE-1-negative, bearing a different molecular signature from blood and true lymphatic vessels. DT walls showed prominent filamentous actin (F-actin) labeling reflecting cells in a contracted state. F-actin co-localized with mesenchymal smooth muscle epitopes of alpha-smooth muscle actin, caldesmon and calponin, which localized adjacent and external to the endothelium. Our findings support a DT wall organization resembling that of blood vessels. This reflects a capacity to contract and support dynamic alteration of DT caliber and resistance analogous to the role of blood vessel tone in regulating blood flow.
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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, USA
| | - Minhee K Ko
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Young-Kwon Hong
- Department of Surgery, Department of Biochemistry and Molecular Biology, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Robert Weigert
- Intracellular Membrane Trafficking Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, USA
| | - James C H Tan
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
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Zhang J, Ren L, Mei X, Xu Q, Zheng W, Liu Z. Microstructure visualization of conventional outflow pathway and finite element modeling analysis of trabecular meshwork. Biomed Eng Online 2016; 15:162. [PMID: 28155681 PMCID: PMC5259963 DOI: 10.1186/s12938-016-0254-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The intraocular pressure (IOP) is maintained through a dynamic equilibrium between the production and drainage of aqueous humor. Elevation of intraocular pressure is mainly caused by the blocking of aqueous humor outflow pathway. Therefore, it is particularly important to study the structure of drainage pathway and the effect of ocular hypertension at the process of aqueous humor outflow. METHODS Conventional drainage pathway of aqueous humor, including trabecular meshwork (TM), Schlemm's canal (SC) and aqueous vein, were imaged by using trans-scleral imaging method with lateral resolution of 2 μm. For quantitative assessment, the morphological parameters of the TM were measured with different IOP levels via a combination of measurements and simulations. RESULTS Images of the TM and the adjacent tissues were obtained. The porosity of TM with normal intraocular pressure varies from 0.63 to 0.74 as the depth increases, while in high IOP it is changed from 0.44 to 0.59. The diameter of aqueous vein varies from 32 to 43 μm, and is smaller than that of SC, which varies from 48 to 64.67 μm. CONCLUSIONS Our research provides a non-contact method to visualize the microstructure of tissue for clinical examination associated with the blocking of the outflow pathway of aqueous humor in humans. The three-dimensional (3D) microstructures of limbus and the results of finite element modeling analysis of the TM model will serve for the future evaluation of new glaucoma surgical techniques.
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Affiliation(s)
- Jing Zhang
- School of Biomedical Engineering, Capital Medical University, Beijing, 100069, China.,Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, 100069, China
| | - Lin Ren
- School of Biomedical Engineering, Capital Medical University, Beijing, 100069, China.,Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, 100069, China
| | - Xi Mei
- School of Biomedical Engineering, Capital Medical University, Beijing, 100069, China.,Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, 100069, China
| | - Qiang Xu
- Shenzhen Key Lab for Molecular Imaging, Research Lab for Biomedical Optics and Molecular Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Wei Zheng
- Shenzhen Key Lab for Molecular Imaging, Research Lab for Biomedical Optics and Molecular Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China.
| | - Zhicheng Liu
- School of Biomedical Engineering, Capital Medical University, Beijing, 100069, China. .,Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, 100069, China.
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Osmond M, Bernier SM, Pantcheva MB, Krebs MD. Collagen and collagen-chondroitin sulfate scaffolds with uniaxially aligned pores for the biomimetic, three dimensional culture of trabecular meshwork cells. Biotechnol Bioeng 2016; 114:915-923. [PMID: 27775151 DOI: 10.1002/bit.26206] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 10/18/2016] [Indexed: 01/01/2023]
Abstract
Glaucoma is a disease in which damage to the optic nerve leads to progressive, irreversible vision loss. The intraocular pressure (IOP) is the only modifiable risk factor for glaucoma and its lowering is considered a useful strategy for preventing or slowing down the progression of glaucomatous neuropathy. Elevated intraocular pressure associated with glaucoma is due to increased aqueous humor outflow resistance, primarily through the trabecular meshwork (TM) of the eye. Current in vitro models of the trabecular meshwork are oversimplified and do not capture the organized and complex three-dimensional nature of this tissue that consists primarily of collagen and glycoasaminoglycans. In this work, collagen and collagen-chondroitin sulfate (CS) scaffolds were fabricated via unidirectional freezing and lyophilization to induce the formation of aligned pores. Scaffolds were characterized by scanning electron microscopy, dynamic mechanical analysis, and a chondroitin sulfate quantification assay. Scaffold characterization confirmed the formation of aligned pores, and also that the CS was leaching out of the scaffolds over time. Primary porcine trabecular meshwork (TM) cells were seeded onto the surface of scaffolds and their gene expression, proliferation, viability, migration into the scaffolds, and morphology were examined. The TM cells were viable and proliferated 2 weeks after seeding. The cells migrated down into the internal scaffold structure and their morphology reflected the topography and alignment of the scaffold structure. This work is a promising step toward the development of a three dimensional in vitro model of the TM that can be used for testing of glaucoma pharmacological agents in future experimentation and to better our understanding of the trabecular meshwork and its complex physiology. Biotechnol. Bioeng. 2017;114: 915-923. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Matthew Osmond
- Department of Chemical and Biological Engineering, Colorado School of Mines, 1613 Illinois Street, 431 Alderson Hall, Golden, 80401, Colorado
| | - Sarah M Bernier
- Department of Chemical and Biological Engineering, Colorado School of Mines, 1613 Illinois Street, 431 Alderson Hall, Golden, 80401, Colorado
| | - Mina B Pantcheva
- Department of Ophthalmology, University of Colorado Denver, 1675 Aurora Court, Aurora, 80045, Colorado
| | - Melissa D Krebs
- Department of Chemical and Biological Engineering, Colorado School of Mines, 1613 Illinois Street, 431 Alderson Hall, Golden, 80401, Colorado
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Huang AS, Mohindroo C, Weinreb RN. Aqueous Humor Outflow Structure and Function Imaging At the Bench and Bedside: A Review. ACTA ACUST UNITED AC 2016; 7. [PMID: 27790380 PMCID: PMC5079182 DOI: 10.4172/2155-9570.1000578] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Anterior segment glaucoma clinical care and research has recently gained new focus because of novel imaging modalities and the advent of angle-based surgical treatments. Traditional investigation drawn to the trabecular meshwork now emphasizes the entire conventional aqueous humor outflow (AHO) pathway from the anterior chamber to the episcleral vein. AHO investigation can be divided into structural and functional assessments using different methods. The historical basis for studying the anterior segment of the eye and AHO in glaucoma is discussed. Structural studies of AHO are reviewed and include traditional pathological approaches to modern tools such as multi-model two-photon microscopy and optical coherence tomography. Functional assessment focuses on visualizing AHO itself through a variety of non-real-time and real-time techniques such as aqueous angiography. Implications of distal outflow resistance and segmental AHO are discussed with an emphasis on melding bench-side research to viable clinical applications. Through the development of an improved structure: function relationship for AHO in the anterior segment of the normal and diseased eye, a better understanding of the eye with improved therapeutics may be developed.
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Affiliation(s)
- Alex S Huang
- Doheny Eye Institute, Los Angeles, CA, USA; Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | | | - Robert N Weinreb
- Hamilton Glaucoma Center and Shiley Eye Institute, University of California, San Diego, CA, USA
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Gonzalez JM, Ko MK, Masedunskas A, Hong YK, Weigert R, Tan JCH. Toward in vivo two-photon analysis of mouse aqueous outflow structure and function. Exp Eye Res 2016; 158:161-170. [PMID: 27179411 DOI: 10.1016/j.exer.2016.05.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 05/05/2016] [Accepted: 05/09/2016] [Indexed: 12/29/2022]
Abstract
The promise of revolutionary insights into intraocular pressure (IOP) and aqueous humor outflow homeostasis, IOP pathogenesis, and novel therapy offered by engineered mouse models has been hindered by a lack of appropriate tools for studying the aqueous drainage tissues in their original 3-dimensional (3D) environment. Advances in 2-photon excitation fluorescence imaging (TPEF) combined with availability of modalities such as transgenic reporter mice and intravital dyes have placed us on the cusp of unlocking the potential of the mouse model for unearthing insights into aqueous drainage structure and function. Multimodality 2-photon imaging permits high-resolution visualization not only of tissue structural organization but also cells and cellular function. It is possible to dig deeper into understanding the cellular basis of aqueous outflow regulation as the technique integrates analysis of tissue structure, cell biology and physiology in a way that could also lead to fresh insights into human glaucoma. We outline recent novel applications of two-photon imaging to analyze the mouse conventional drainage system in vivo or in whole tissues: (1) collagen second harmonic generation (SHG) identifies the locations of episcleral vessels, intrascleral plexuses, collector channels, and Schlemm's canal in the distal aqueous drainage tract; (2) the prospero homeobox protein 1-green fluorescent protein (GFP) reporter helps locate the inner wall of Schlemm's canal; (3) Calcein AM, siGLO™, the fluorescent reporters m-Tomato and GFP, and coherent anti-Stokes scattering (CARS), are adjuncts to TPEF to identify live cells by their membrane or cytosolic locations; (4) autofluorescence and sulforhodamine-B to identify elastic fibers in the living eye. These tools greatly expand our options for analyzing physiological and pathological processes in the aqueous drainage tissues of live mice as a model of the analogous human system.
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Affiliation(s)
- Jose M Gonzalez
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Minhee K Ko
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Andrius Masedunskas
- Intracellular Membrane Trafficking Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Young-Kwon Hong
- Department of Surgery, Department of Biochemistry and Molecular Biology, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Roberto Weigert
- Intracellular Membrane Trafficking Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - James C H Tan
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
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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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