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Sharkova M, Aparicio G, Mouzaaber C, Zolessi FR, Hocking JC. Photoreceptor calyceal processes accompany the developing outer segment, adopting a stable length despite a dynamic core. J Cell Sci 2024; 137:jcs261721. [PMID: 38477343 PMCID: PMC11058337 DOI: 10.1242/jcs.261721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 03/04/2024] [Indexed: 03/14/2024] Open
Abstract
Vertebrate photoreceptors detect light through a large cilium-based outer segment, which is filled with photopigment-laden membranous discs. Surrounding the base of the outer segment are microvilli-like calyceal processes (CPs). Although CP disruption has been associated with altered outer segment morphology and photoreceptor degeneration, the role of the CPs remains elusive. Here, we used zebrafish as a model to characterize CPs. We quantified CP parameters and report a strong disparity in outer segment coverage between photoreceptor subtypes. CP length is stable across light and dark conditions, yet heat-shock inducible expression of tagged actin revealed rapid turnover of the CP actin core. Detailed imaging of the embryonic retina uncovered substantial remodeling of the developing photoreceptor apical surface, including a transition from dynamic tangential processes to vertically oriented CPs immediately prior to outer segment formation. Remarkably, we also found a direct connection between apical extensions of the Müller glia and retinal pigment epithelium, arranged as bundles around the ultraviolet sensitive cones. In summary, our data characterize the structure, development and surrounding environment of photoreceptor microvilli in the zebrafish retina.
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Affiliation(s)
- Maria Sharkova
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Gonzalo Aparicio
- Sección Biología Celular, Facultad de Ciencias, Universidad de la República, 11400, Uruguay
- Institut Pasteur Montevideo, Uruguay
| | - Constantin Mouzaaber
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Flavio R. Zolessi
- Sección Biología Celular, Facultad de Ciencias, Universidad de la República, 11400, Uruguay
- Institut Pasteur Montevideo, Uruguay
| | - Jennifer C. Hocking
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
- Division of Anatomy, Department of Surgery, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
- Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada
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2
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Giannini JP, Lu R, Bower AJ, Fariss R, Tam J. Visualizing retinal cells with adaptive optics imaging modalities using a translational imaging framework. BIOMEDICAL OPTICS EXPRESS 2022; 13:3042-3055. [PMID: 35774328 PMCID: PMC9203084 DOI: 10.1364/boe.454560] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 04/08/2022] [Accepted: 04/08/2022] [Indexed: 05/18/2023]
Abstract
Adaptive optics reflectance-based retinal imaging has proved a valuable tool for the noninvasive visualization of cells in the living human retina. Many subcellular features that remain at or below the resolution limit of current in vivo techniques may be more easily visualized with the same modalities in an ex vivo setting. While most microscopy techniques provide significantly higher resolution, enabling the visualization of fine cellular detail in ex vivo retinal samples, they do not replicate the reflectance-based imaging modalities of in vivo retinal imaging. Here, we introduce a strategy for imaging ex vivo samples using the same imaging modalities as those used for in vivo retinal imaging, but with increased resolution. We also demonstrate the ability of this approach to perform protein-specific fluorescence imaging and reflectance imaging simultaneously, enabling the visualization of nearly transparent layers of the retina and the classification of cone photoreceptor types.
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3
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Borrelli E, Grosso D, Barresi C, Lari G, Sacconi R, Senni C, Querques L, Bandello F, Querques G. Long-Term Visual Outcomes and Morphologic Biomarkers of Vision Loss in Eyes With Diabetic Macular Edema Treated With Anti-VEGF Therapy. Am J Ophthalmol 2022; 235:80-89. [PMID: 34509431 DOI: 10.1016/j.ajo.2021.09.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 09/02/2021] [Accepted: 09/02/2021] [Indexed: 12/20/2022]
Abstract
PURPOSE To analyze the morphological characteristics and long-term visual outcomes in eyes with diabetic retinopathy (DR) and diabetic macular edema (DME) treated with anti-vascular endothelial growth factor (anti-VEGF) therapy. DESIGN Retrospective clinical cohort study. METHODS Patients with a long-term follow-up and evidence of resolved DME in at least 1 visit (study visit) after 5 years of follow-up after the initiation of anti-VEGF therapy were included. At the study visit, structural optical coherence tomography (OCT) scans were reviewed for qualitative features reflecting a distress of the neuroretina or retinal pigment epithelium (RPE). A quantitative topographical assessment of the inner and outer retinal thicknesses was also provided. RESULTS A total of 61 eyes (50 patients) were included and were divided into 2 subgroups according to visual acuity (VA) at the study visit, yielding a group of 24 eyes with a VA <20/40 ("poor/intermediate vision" group), and 37 eyes with a VA ≥20/40 ("good vision" group). The external limiting membrane (ELM) and RPE bands were more frequently disrupted or absent in the poor/intermediate vision group (P = .003 and P = .019). Similarly, disorganization of retinal inner layers was more prevalent in the poor/intermediate vision group (P = .013). The foveal and parafoveal outer retinal thicknesses were reduced in eyes with poor/intermediate vision (P = .022 and P = .044). Multivariate stepwise linear regression analysis demonstrated that VA was associated with appearances of the RPE and ELM (P < .0001 and P = .048), foveal and parafoveal outer retinal thicknesses (P = .046 and P = .035). CONCLUSIONS Modifications in the outer retina and RPE represent OCT biomarkers of long-term visual outcomes in eyes with DME treated with anti-VEGF.
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4
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Kicková E, Sadeghi A, Puranen J, Tavakoli S, Sen M, Ranta VP, Arango-Gonzalez B, Bolz S, Ueffing M, Salmaso S, Caliceti P, Toropainen E, Ruponen M, Urtti A. Pharmacokinetics of Pullulan-Dexamethasone Conjugates in Retinal Drug Delivery. Pharmaceutics 2021; 14:pharmaceutics14010012. [PMID: 35056906 PMCID: PMC8779473 DOI: 10.3390/pharmaceutics14010012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 12/11/2021] [Accepted: 12/17/2021] [Indexed: 12/11/2022] Open
Abstract
The treatment of retinal diseases by intravitreal injections requires frequent administration unless drug delivery systems with long retention and controlled release are used. In this work, we focused on pullulan (≈67 kDa) conjugates of dexamethasone as therapeutic systems for intravitreal administration. The pullulan-dexamethasone conjugates self-assemble into negatively charged nanoparticles (average size 326 ± 29 nm). Intravitreal injections of pullulan and pullulan-dexamethasone were safe in mouse, rat and rabbit eyes. Fluorescently labeled pullulan particles showed prolonged retention in the vitreous and they were almost completely eliminated via aqueous humor outflow. Pullulan conjugates also distributed to the retina via Müller glial cells when tested in ex vivo retina explants and in vivo. Pharmacokinetic simulations showed that pullulan-dexamethasone conjugates may release free and active dexamethasone in the vitreous humor for over 16 days, even though a large fraction of dexamethasone may be eliminated from the eye as bound pullulan-dexamethasone. We conclude that pullulan based drug conjugates are promising intravitreal drug delivery systems as they may reduce injection frequency and deliver drugs into the retinal cells.
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Affiliation(s)
- Eva Kicková
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Via F. Marzolo 5, 35131 Padova, Italy; (E.K.); (S.S.); (P.C.)
| | - Amir Sadeghi
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Yliopistonranta 1C, 70211 Kuopio, Finland; (A.S.); (J.P.); (V.-P.R.); (E.T.); (M.R.)
| | - Jooseppi Puranen
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Yliopistonranta 1C, 70211 Kuopio, Finland; (A.S.); (J.P.); (V.-P.R.); (E.T.); (M.R.)
| | - Shirin Tavakoli
- Drug Research Program, Faculty of Pharmacy, University of Helsinki, Viikinkaari 5E, 00710 Helsinki, Finland;
| | - Merve Sen
- Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Elfriede-Aulhorn-Str. 7, D-72076 Tübingen, Germany; (M.S.); (B.A.-G.); (S.B.); (M.U.)
| | - Veli-Pekka Ranta
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Yliopistonranta 1C, 70211 Kuopio, Finland; (A.S.); (J.P.); (V.-P.R.); (E.T.); (M.R.)
| | - Blanca Arango-Gonzalez
- Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Elfriede-Aulhorn-Str. 7, D-72076 Tübingen, Germany; (M.S.); (B.A.-G.); (S.B.); (M.U.)
| | - Sylvia Bolz
- Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Elfriede-Aulhorn-Str. 7, D-72076 Tübingen, Germany; (M.S.); (B.A.-G.); (S.B.); (M.U.)
| | - Marius Ueffing
- Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Elfriede-Aulhorn-Str. 7, D-72076 Tübingen, Germany; (M.S.); (B.A.-G.); (S.B.); (M.U.)
| | - Stefano Salmaso
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Via F. Marzolo 5, 35131 Padova, Italy; (E.K.); (S.S.); (P.C.)
| | - Paolo Caliceti
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Via F. Marzolo 5, 35131 Padova, Italy; (E.K.); (S.S.); (P.C.)
| | - Elisa Toropainen
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Yliopistonranta 1C, 70211 Kuopio, Finland; (A.S.); (J.P.); (V.-P.R.); (E.T.); (M.R.)
| | - Marika Ruponen
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Yliopistonranta 1C, 70211 Kuopio, Finland; (A.S.); (J.P.); (V.-P.R.); (E.T.); (M.R.)
| | - Arto Urtti
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Yliopistonranta 1C, 70211 Kuopio, Finland; (A.S.); (J.P.); (V.-P.R.); (E.T.); (M.R.)
- Drug Research Program, Faculty of Pharmacy, University of Helsinki, Viikinkaari 5E, 00710 Helsinki, Finland;
- Institute of Chemistry, St. Petersburg State University, Petergof, Universitetskii pr. 26, 198504 St. Petersburg, Russia
- Correspondence:
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5
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Balay SD, Hochstoeger T, Vilceanu A, Malkemper EP, Snider W, Dürnberger G, Mechtler K, Schuechner S, Ogris E, Nordmann GC, Ushakova L, Nimpf S, Keays DA. The expression, localisation and interactome of pigeon CRY2. Sci Rep 2021; 11:20293. [PMID: 34645873 PMCID: PMC8514597 DOI: 10.1038/s41598-021-99207-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 09/13/2021] [Indexed: 11/18/2022] Open
Abstract
Cryptochromes (CRY) are highly conserved signalling molecules that regulate circadian rhythms and are candidate radical pair based magnetoreceptors. Birds have at least four cryptochromes (CRY1a, CRY1b, CRY2, and CRY4), but few studies have interrogated their function. Here we investigate the expression, localisation and interactome of clCRY2 in the pigeon retina. We report that clCRY2 has two distinct transcript variants, clCRY2a, and a previously unreported splice isoform, clCRY2b which is larger in size. We show that clCRY2a mRNA is expressed in all retinal layers and clCRY2b is enriched in the inner and outer nuclear layer. To define the localisation and interaction network of clCRY2 we generated and validated a monoclonal antibody that detects both clCRY2 isoforms. Immunohistochemical studies revealed that clCRY2a/b is present in all retinal layers and is enriched in the outer limiting membrane and outer plexiform layer. Proteomic analysis showed clCRY2a/b interacts with typical circadian molecules (PER2, CLOCK, ARTNL), cell junction proteins (CTNNA1, CTNNA2) and components associated with the microtubule motor dynein (DYNC1LI2, DCTN1, DCTN2, DCTN3) within the retina. Collectively these data show that clCRY2 is a component of the avian circadian clock and unexpectedly associates with the microtubule cytoskeleton.
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Affiliation(s)
- Spencer D Balay
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus Vienna Biocenter 1, 1030, Vienna, Austria.,Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, 1030, Vienna, Austria
| | - Tobias Hochstoeger
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus Vienna Biocenter 1, 1030, Vienna, Austria
| | - Alexandra Vilceanu
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus Vienna Biocenter 1, 1030, Vienna, Austria
| | - E Pascal Malkemper
- Max Planck Research Group Neurobiology of Magnetoreception, Center of Advanced European Studies and Research (Caesar), Ludwig-Erhard-Allee 2, 53175, Bonn, Germany
| | - William Snider
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, USA
| | - Gerhard Dürnberger
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus Vienna Biocenter 1, 1030, Vienna, Austria.,Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), Dr. Bohr-Gasse 3, 1030, Vienna, Austria
| | - Karl Mechtler
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus Vienna Biocenter 1, 1030, Vienna, Austria.,Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), Dr. Bohr-Gasse 3, 1030, Vienna, Austria
| | - Stefan Schuechner
- Monoclonal Antibody Facility, Max Perutz Labs, Medical University of Vienna, Dr. Bohr-Gasse 9, 1030, Vienna, Austria
| | - Egon Ogris
- Monoclonal Antibody Facility, Max Perutz Labs, Medical University of Vienna, Dr. Bohr-Gasse 9, 1030, Vienna, Austria
| | - Gregory C Nordmann
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus Vienna Biocenter 1, 1030, Vienna, Austria.,Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, 1030, Vienna, Austria
| | - Lyubov Ushakova
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus Vienna Biocenter 1, 1030, Vienna, Austria
| | - Simon Nimpf
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus Vienna Biocenter 1, 1030, Vienna, Austria
| | - David A Keays
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Campus Vienna Biocenter 1, 1030, Vienna, Austria. .,Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Australia. .,Division of Neurobiology, Department Biology II, Ludwig-Maximilians-University Munich, Planegg-Martinsried, 82152, Munich, Germany.
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6
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Andreazzoli M, Barravecchia I, De Cesari C, Angeloni D, Demontis GC. Inducible Pluripotent Stem Cells to Model and Treat Inherited Degenerative Diseases of the Outer Retina: 3D-Organoids Limitations and Bioengineering Solutions. Cells 2021; 10:cells10092489. [PMID: 34572137 PMCID: PMC8471616 DOI: 10.3390/cells10092489] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 09/12/2021] [Accepted: 09/15/2021] [Indexed: 12/12/2022] Open
Abstract
Inherited retinal degenerations (IRD) affecting either photoreceptors or pigment epithelial cells cause progressive visual loss and severe disability, up to complete blindness. Retinal organoids (ROs) technologies opened up the development of human inducible pluripotent stem cells (hiPSC) for disease modeling and replacement therapies. However, hiPSC-derived ROs applications to IRD presently display limited maturation and functionality, with most photoreceptors lacking well-developed outer segments (OS) and light responsiveness comparable to their adult retinal counterparts. In this review, we address for the first time the microenvironment where OS mature, i.e., the subretinal space (SRS), and discuss SRS role in photoreceptors metabolic reprogramming required for OS generation. We also address bioengineering issues to improve culture systems proficiency to promote OS maturation in hiPSC-derived ROs. This issue is crucial, as satisfying the demanding metabolic needs of photoreceptors may unleash hiPSC-derived ROs full potential for disease modeling, drug development, and replacement therapies.
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Affiliation(s)
| | - Ivana Barravecchia
- Department of Pharmacy, University of Pisa, 56126 Pisa, Italy;
- Institute of Life Sciences, Scuola Superiore Sant’Anna, 56124 Pisa, Italy;
| | | | - Debora Angeloni
- Institute of Life Sciences, Scuola Superiore Sant’Anna, 56124 Pisa, Italy;
| | - Gian Carlo Demontis
- Department of Pharmacy, University of Pisa, 56126 Pisa, Italy;
- Correspondence: (M.A.); (G.C.D.)
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7
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Lankford CK, Laird JG, Inamdar SM, Baker SA. A Comparison of the Primary Sensory Neurons Used in Olfaction and Vision. Front Cell Neurosci 2020; 14:595523. [PMID: 33250719 PMCID: PMC7676898 DOI: 10.3389/fncel.2020.595523] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Accepted: 10/06/2020] [Indexed: 12/18/2022] Open
Abstract
Vision, hearing, smell, taste, and touch are the tools used to perceive and navigate the world. They enable us to obtain essential resources such as food and highly desired resources such as mates. Thanks to the investments in biomedical research the molecular unpinning’s of human sensation are rivaled only by our knowledge of sensation in the laboratory mouse. Humans rely heavily on vision whereas mice use smell as their dominant sense. Both modalities have many features in common, starting with signal detection by highly specialized primary sensory neurons—rod and cone photoreceptors (PR) for vision, and olfactory sensory neurons (OSN) for the smell. In this chapter, we provide an overview of how these two types of primary sensory neurons operate while highlighting the similarities and distinctions.
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Affiliation(s)
- Colten K Lankford
- Department of Biochemistry, University of Iowa, Iowa City, IA, United States
| | - Joseph G Laird
- Department of Biochemistry, University of Iowa, Iowa City, IA, United States
| | - Shivangi M Inamdar
- Department of Biochemistry, University of Iowa, Iowa City, IA, United States
| | - Sheila A Baker
- Department of Biochemistry, University of Iowa, Iowa City, IA, United States.,Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, IA, United States
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8
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Nadolski NJ, Balay SD, Wong CXL, Waskiewicz AJ, Hocking JC. Abnormal Cone and Rod Photoreceptor Morphogenesis in gdf6a Mutant Zebrafish. Invest Ophthalmol Vis Sci 2020; 61:9. [PMID: 32293666 PMCID: PMC7401959 DOI: 10.1167/iovs.61.4.9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Purpose Analysis of photoreceptor morphology and gene expression in mispatterned eyes of zebrafish growth differentiation factor 6a (gdf6a) mutants. Methods Rod and cone photoreceptors were compared between gdf6a mutant and control zebrafish from larval to late adult stages using transgenic labels, immunofluorescence, and confocal microscopy, as well as by transmission electron microscopy. To compare transcriptomes between larval gdf6a mutant and control zebrafish, RNA-Seq was performed on isolated eyes. Results Although rod and cone photoreceptors differentiate in gdf6a mutant zebrafish, the cells display aberrant growth and morphology. The cone outer segments, the light-detecting sensory endings, are reduced in size in the mutant larvae and fail to recover to control size at subsequent stages. In contrast, rods form temporarily expanded outer segments. The inner segments, which generate the required energy and proteins for the outer segments, are shortened in both rods and cones at all stages. RNA-Seq analysis provides a set of misregulated genes associated with the observed abnormal photoreceptor morphogenesis. Conclusions GDF6 mutations were previously identified in patients with Leber congenital amaurosis. Here, we reveal a unique photoreceptor phenotype in the gdf6a mutant zebrafish whereby rods and cones undergo abnormal maturation distinct for each cell type. Further, subsequent development shows partial recovery of cell morphology and maintenance of the photoreceptor layer. By conducting a transcriptomic analysis of the gdf6a larval eyes, we identified a collection of genes that are candidate regulators of photoreceptor size and morphology.
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9
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Eastlake K, Luis J, Limb GA. Potential of Müller Glia for Retina Neuroprotection. Curr Eye Res 2020; 45:339-348. [PMID: 31355675 DOI: 10.1080/02713683.2019.1648831] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 07/19/2019] [Indexed: 12/26/2022]
Abstract
Müller glia constitute the main glial cells of the retina. They are spatially distributed along this tissue, facilitating their close membrane interactions with all retinal neurons. Müller glia are characterized by their active metabolic functions, which are neuroprotective in nature. Although they can become reactive under pathological conditions, leading to their production of inflammatory and neurotoxic factors, their main metabolic functions confer neuroprotection to the retina, resulting in the promotion of neural cell repair and survival. In addition to their protective metabolic features, Müller glia release several neurotrophic factors and antioxidants into the retinal microenvironment, which are taken up by retinal neurons for their survival. This review summarizes the Müller glial neuroprotective mechanisms and describes advances made on the clinical application of these factors for the treatment of retinal degenerative diseases. It also discusses prospects for the use of these cells as a vehicle to deliver neuroprotective factors into the retina.
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Affiliation(s)
- Karen Eastlake
- UCL Institute of Ophthalmology and NIHR Biomedical Research Centre at Moorfields Eye Hospital, London, UK
| | - Joshua Luis
- UCL Institute of Ophthalmology and NIHR Biomedical Research Centre at Moorfields Eye Hospital, London, UK
| | - G Astrid Limb
- UCL Institute of Ophthalmology and NIHR Biomedical Research Centre at Moorfields Eye Hospital, London, UK
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10
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Wilkerson JL, Stiles MA, Gurley JM, Grambergs RC, Gu X, Elliott MH, Proia RL, Mandal NA. Sphingosine Kinase-1 Is Essential for Maintaining External/Outer Limiting Membrane and Associated Adherens Junctions in the Aging Retina. Mol Neurobiol 2019; 56:7188-7207. [PMID: 30997640 DOI: 10.1007/s12035-019-1599-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 04/02/2019] [Indexed: 11/24/2022]
Abstract
Sphingosine-1-phosphate (S1P) produced by sphingosine kinases (SPHK1 and SPHK2) is a signaling molecule involved in cell proliferation and formation of cellular junctions. In this study, we characterized the retinas of Sphk1 knockout (KO) mice by electron microscopy and immunocytochemistry. We also tested cultured Müller glia for their response to S1P. We found that S1P plays an important role in retinal and retinal pigment epithelial (RPE) structural integrity in aging mice. Ultrastructural analysis of Sphk1 KO mouse retinas aged to 15 months or raised with moderate light stress revealed a degenerated outer limiting membrane (OLM). This membrane is formed by adherens junctions between neighboring Müller glia and photoreceptor cells. We also show that Sphk1 KO mice have reduced retinal function in mice raised with moderate light stress. In vitro assays revealed that exogenous S1P modulated cytoskeletal rearrangement and increased N-cadherin production in human Müller glia cells. Aged mice also had morphological degeneration of the RPE, as well as increased lipid storage vacuoles and undigested phagosomes reminiscent of RPE in age-related macular degeneration. These findings show that SPHK1 and S1P play a vital role in the structural maintenance of the mammalian retina and retinal pigmented epithelium by supporting the formation of adherens junctions.
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Affiliation(s)
- Joseph L Wilkerson
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA.,Dean A. McGee Eye Institute, Oklahoma City, OK, 73104, USA
| | - Megan A Stiles
- Dean A. McGee Eye Institute, Oklahoma City, OK, 73104, USA.,Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Jami M Gurley
- Dean A. McGee Eye Institute, Oklahoma City, OK, 73104, USA.,Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Richard C Grambergs
- Department of Ophthalmology and Anatomy and Neurobiology, University of Tennessee Health Sciences Center, Memphis, TN, 38163, USA
| | - Xiaowu Gu
- Dean A. McGee Eye Institute, Oklahoma City, OK, 73104, USA.,Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Michael H Elliott
- Dean A. McGee Eye Institute, Oklahoma City, OK, 73104, USA.,Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Richard L Proia
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Nawajes A Mandal
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA. .,Dean A. McGee Eye Institute, Oklahoma City, OK, 73104, USA. .,Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA. .,Department of Ophthalmology and Anatomy and Neurobiology, University of Tennessee Health Sciences Center, Memphis, TN, 38163, USA. .,Department of Ophthalmology, Hamilton Eye Institute, University of Tennessee Health Sciences Center, 930 Madison Avenue, Suite 718, Memphis, TN, 38163, USA. .,Department of Anatomy and Neurobiology, Hamilton Eye Institute, University of Tennessee Health Sciences Center, 930 Madison Avenue, Suite 718, Memphis, TN, 38163, USA.
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11
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Curcio CA. Antecedents of Soft Drusen, the Specific Deposits of Age-Related Macular Degeneration, in the Biology of Human Macula. Invest Ophthalmol Vis Sci 2018; 59:AMD182-AMD194. [PMID: 30357337 PMCID: PMC6733529 DOI: 10.1167/iovs.18-24883] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
AMD pathobiology was irreversibly changed by the recent discovery of extracellular cholesterol-containing deposits in the subretinal space, between the photoreceptors and retinal pigment epithelium (RPE), called subretinal drusenoid deposits (SDDs). SDDs strikingly mirror the topography of rod photoreceptors in human macula, raising the question of whether an equivalent process results in a deposition related to foveal cones. Herein we propose that AMD's pathognomonic lesion-soft drusen and basal linear deposit (BLinD, same material, diffusely distributed)-is the leading candidate. Epidemiologic, clinical, and histologic data suggest that these deposits are most abundant in the central macula, under the fovea. Strong evidence presented in a companion article supports the idea that the dominant ultrastructural component is large apolipoprotein B,E-containing lipoproteins, constitutively secreted by RPE. Lipoprotein fatty acids are dominated by linoleate (implicating diet) rather than docosahexaenoate (implicating photoreceptors); we seek within the retina cellular relationships and dietary drivers to explain soft druse topography. The delivery of xanthophyll pigments to highly evolved and numerous Müller cells in the human fovea, through RPE, is one strong candidate, because Müller cells are the main reservoir of these pigments, which replenish from diet. We propose that the evolution of neuroglial relations and xanthophyll delivery that underlie exquisite human foveal vision came with a price, that is, soft drusen and sequela, long after our reproductive years.
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Affiliation(s)
- Christine A Curcio
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
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12
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OPTICAL COHERENCE TOMOGRAPHY AND HISTOLOGY OF AGE-RELATED MACULAR DEGENERATION SUPPORT MITOCHONDRIA AS REFLECTIVITY SOURCES. Retina 2018; 38:445-461. [PMID: 29210936 DOI: 10.1097/iae.0000000000001946] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
PURPOSE Widespread adoption of optical coherence tomography has revolutionized the diagnosis and management of retinal disease. If the cellular and subcellular sources of reflectivity in optical coherence tomography can be identified, the value of this technology will be advanced even further toward precision medicine, mechanistic thinking, and molecular discovery. Four hyperreflective outer retinal bands are created by the exquisite arrangement of photoreceptors, Müller cells, retinal pigment epithelium, and Bruch membrane. Because of massed effects of these axially compartmentalized and transversely aligned cells, reflectivity can be localized to the subcellular level. This review focuses on the second of the four bands, called ellipsoid zone in a consensus clinical lexicon, with the central thesis that mitochondria in photoreceptor inner segments are a major independent reflectivity source in this band, because of Mie scattering and waveguiding. METHODS We review the evolution of Band 2 nomenclature in published literature and discuss the origins of imaging signals from photoreceptor mitochondria that could make these organelles visible in vivo. RESULTS Our recent data pertain to outer retinal tubulation, a unique neurodegenerative and gliotic structure with a highly reflective border, prominent in late age-related macular degeneration. High-resolution histology and multimodal imaging of outer retinal tubulation together provide evidence that inner segment mitochondria undergoing fission and translocation toward the nucleus provide the reflectivity signal. CONCLUSION Our data support adoption of the ellipsoid zone nomenclature. Identifying subcellular signal sources will newly inform clinical.
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Bringmann A, Syrbe S, Görner K, Kacza J, Francke M, Wiedemann P, Reichenbach A. The primate fovea: Structure, function and development. Prog Retin Eye Res 2018; 66:49-84. [PMID: 29609042 DOI: 10.1016/j.preteyeres.2018.03.006] [Citation(s) in RCA: 182] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 03/20/2018] [Accepted: 03/27/2018] [Indexed: 01/31/2023]
Abstract
A fovea is a pitted invagination in the inner retinal tissue (fovea interna) that overlies an area of photoreceptors specialized for high acuity vision (fovea externa). Although the shape of the vertebrate fovea varies considerably among the species, there are two basic types. The retina of many predatory fish, reptilians, and birds possess one (or two) convexiclivate fovea(s), while the retina of higher primates contains a concaviclivate fovea. By refraction of the incoming light, the convexiclivate fovea may function as image enlarger, focus indicator, and movement detector. By centrifugal displacement of the inner retinal layers, which increases the transparency of the central foveal tissue (the foveola), the primate fovea interna improves the quality of the image received by the central photoreceptors. In this review, we summarize ‒ with the focus on Müller cells of the human and macaque fovea ‒ data regarding the structure of the primate fovea, discuss various aspects of the optical function of the fovea, and propose a model of foveal development. The "Müller cell cone" of the foveola comprises specialized Müller cells which do not support neuronal activity but may serve optical and structural functions. In addition to the "Müller cell cone", structural stabilization of the foveal morphology may be provided by the 'z-shaped' Müller cells of the fovea walls, via exerting tractional forces onto Henle fibers. The spatial distribution of glial fibrillary acidic protein may suggest that the foveola and the Henle fiber layer are subjects to mechanical stress. During development, the foveal pit is proposed to be formed by a vertical contraction of the centralmost Müller cells. After widening of the foveal pit likely mediated by retracting astrocytes, Henle fibers are formed by horizontal contraction of Müller cell processes in the outer plexiform layer and the centripetal displacement of photoreceptors. A better understanding of the molecular, cellular, and mechanical factors involved in the developmental morphogenesis and the structural stabilization of the fovea may help to explain the (patho-) genesis of foveal hypoplasia and macular holes.
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Affiliation(s)
- Andreas Bringmann
- Department of Ophthalmology and Eye Hospital, Medical Faculty, University of Leipzig, 04103 Leipzig, Germany
| | - Steffen Syrbe
- Paul Flechsig Institute of Brain Research, Medical Faculty, University of Leipzig, 04103 Leipzig, Germany
| | - Katja Görner
- Paul Flechsig Institute of Brain Research, Medical Faculty, University of Leipzig, 04103 Leipzig, Germany
| | - Johannes Kacza
- Saxon Incubator for Clinical Translation (SIKT), Leipzig University, 04103 Leipzig, Germany
| | - Mike Francke
- Paul Flechsig Institute of Brain Research, Medical Faculty, University of Leipzig, 04103 Leipzig, Germany; Saxon Incubator for Clinical Translation (SIKT), Leipzig University, 04103 Leipzig, Germany
| | - Peter Wiedemann
- Department of Ophthalmology and Eye Hospital, Medical Faculty, University of Leipzig, 04103 Leipzig, Germany
| | - Andreas Reichenbach
- Paul Flechsig Institute of Brain Research, Medical Faculty, University of Leipzig, 04103 Leipzig, Germany.
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Govetto A, Bhavsar KV, Virgili G, Gerber MJ, Freund KB, Curcio CA, Burgoyne CF, Hubschman JP, Sarraf D. Tractional Abnormalities of the Central Foveal Bouquet in Epiretinal Membranes: Clinical Spectrum and Pathophysiological Perspectives. Am J Ophthalmol 2017; 184:167-180. [PMID: 29106913 DOI: 10.1016/j.ajo.2017.10.011] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2017] [Revised: 10/16/2017] [Accepted: 10/18/2017] [Indexed: 10/18/2022]
Abstract
PURPOSE To investigate the tractional alterations of the central bouquet (CB) in idiopathic epiretinal membranes (ERMs). DESIGN Retrospective, consecutive, observational case series. METHODS ERMs were classified according to a 4-stage grading system. The CB was defined as a circular area of approximately 100 μm composed of densely packed cones (and Müller cells) in the central fovea. Tractional abnormalities of the CB were identified with spectral-domain optical coherence tomography. Ex vivo histopathologic analysis was performed. RESULTS In this study 263 eyes with ERMs were included. Mean follow-up was 21.2 ± 16.7 months. At baseline, tractional abnormalities of the CB were diagnosed in 58 out of 263 eyes (22%) and divided into 3 categories: cotton ball sign (defined as a fuzzy hyperreflective area between the ellipsoid zone and the interdigitation zone in the central fovea), foveolar detachment, and acquired vitelliform lesion. The presence of ectopic inner foveal layers was negatively correlated with the presence of CB tractional abnormalities (P = .002). Visual acuity was highest in association with the cotton ball sign and lowest in the acquired vitelliform lesion group. Sequential morphologic progression was identified in 7 eyes. Ex vivo histopathologic analysis illustrated characteristic staining patterns supporting a potential mechanism of traction by Müller cells in the CB. CONCLUSIONS The cotton ball sign, foveolar detachment, and acquired vitelliform lesion may comprise a continuum in the same clinical spectrum and may represent subsequent stages of CB abnormalities. Foveal Müller cells may play an integral role in the transmission of mechanical forces to the central foveal cones.
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Nagashima M, Hadidjojo J, Barthel LK, Lubensky DK, Raymond PA. Anisotropic Müller glial scaffolding supports a multiplex lattice mosaic of photoreceptors in zebrafish retina. Neural Dev 2017; 12:20. [PMID: 29141686 PMCID: PMC5688757 DOI: 10.1186/s13064-017-0096-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 10/19/2017] [Indexed: 11/21/2022] Open
Abstract
Background The multiplex, lattice mosaic of cone photoreceptors in the adult fish retina is a compelling example of a highly ordered epithelial cell pattern, with single cell width rows and columns of cones and precisely defined neighbor relationships among different cone types. Cellular mechanisms patterning this multiplex mosaic are not understood. Physical models can provide new insights into fundamental mechanisms of biological patterning. In earlier work, we developed a mathematical model of photoreceptor cell packing in the zebrafish retina, which predicted that anisotropic mechanical tension in the retinal epithelium orients planar polarized adhesive interfaces to align the columns as cone photoreceptors are generated at the retinal margin during post-embryonic growth. Methods With cell-specific fluorescent reporters and in vivo imaging of the growing retinal margin in transparent juvenile zebrafish we provide the first view of how cell packing, spatial arrangement, and cell identity are coordinated to build the lattice mosaic. With targeted laser ablation we probed the tissue mechanics of the retinal epithelium. Results Within the lattice mosaic, planar polarized Crumbs adhesion proteins pack cones into a single cell width column; between columns, N-cadherin-mediated adherens junctions stabilize Müller glial apical processes. The concentration of activated pMyosin II at these punctate adherens junctions suggests that these glial bands are under tension, forming a physical barrier between cone columns and contributing to mechanical stress anisotropies in the epithelial sheet. Unexpectedly, we discovered that the appearance of such parallel bands of Müller glial apical processes precedes the packing of cones into single cell width columns, hinting at a possible role for glia in the initial organization of the lattice mosaic. Targeted laser ablation of Müller glia directly demonstrates that these glial processes support anisotropic mechanical tension in the planar dimension of the retinal epithelium. Conclusions These findings uncovered a novel structural feature of Müller glia associated with alignment of photoreceptors into a lattice mosaic in the zebrafish retina. This is the first demonstration, to our knowledge, of planar, anisotropic mechanical forces mediated by glial cells. Electronic supplementary material The online version of this article (10.1186/s13064-017-0096-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Mikiko Nagashima
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, 830 North University Avenue, Ann Arbor, MI, 48109-1048, USA
| | - Jeremy Hadidjojo
- Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, MI, 48109-1040, USA
| | - Linda K Barthel
- Microscopy and Image Analysis Laboratory, University of Michigan, Ann Arbor, MI, USA
| | - David K Lubensky
- Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, MI, 48109-1040, USA.
| | - Pamela A Raymond
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, 830 North University Avenue, Ann Arbor, MI, 48109-1048, USA.
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Litts KM, Ach T, Hammack KM, Sloan KR, Zhang Y, Freund KB, Curcio CA. Quantitative Analysis of Outer Retinal Tubulation in Age-Related Macular Degeneration From Spectral-Domain Optical Coherence Tomography and Histology. Invest Ophthalmol Vis Sci 2017; 57:2647-56. [PMID: 27177321 PMCID: PMC4868096 DOI: 10.1167/iovs.16-19262] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Purpose To assess outer retinal tubulation (ORT) morphology from spectral-domain optical coherence tomography (SD-OCT) volumes and donor eye histology, analyze ORT reflectivity, and estimate the number of cones surviving in ORT. Methods In SD-OCT volumes from nine patients with advanced AMD, ORT was analyzed en face and in B-scans. The hyperreflective ORT border in cross-section was delineated and surface area calculated. Reflectivity was compared between ORT types (Closed, Open, Forming, and Branching). A flatmount retina from a donor with neovascular AMD was labeled to visualize the external limiting membrane that delimits ORT and allow measurements of cross-sectional cone area, center-to-center cone spacing, and cone density. The number of cones surviving in ORT was estimated. Results By en face SD-OCT, ORT varies in complexity and shape. Outer retinal tubulation networks almost always contain Closed cross-sections. Spectral-domain OCT volumes containing almost exclusively Closed ORTs showed no significant direction-dependent differences in hyperreflective ORT border intensity. The surface areas of partial ORT assessed by SD-OCT volumes ranged from 0.16 to 1.76 mm2. From the flatmount retina, the average cross-sectional area of cone inner segments was 49.1 ± 7.9 μm2. The average cone spacing was 7.5 ± 0.6 μm. Outer retinal tubulation cone density was 20,351 cones/mm2. The estimated number of cones in ORT in a macula ranged from 26,399 to 186,833 cones, which is 6% to 44% of the cones present in a healthy macula. Conclusions These first estimates for cone density and number of cones surviving in ORT suggest that ORT formation considerably distorts the photoreceptor mosaic. Results provide additional insight into the reflectivity characteristics and number of ORT cones observable in living patients by SD-OCT, as cones persist and disease progresses.
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Affiliation(s)
- Katie M Litts
- Department of Ophthalmology University of Alabama School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States 2Vision Science Graduate Program, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Thomas Ach
- Department of Ophthalmology University of Alabama School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States 3Department of Ophthalmology, University Hospital Würzburg, Würzburg, Germany
| | - Kristen M Hammack
- Department of Ophthalmology University of Alabama School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States 4Department of Computer and Information Sciences, University of Alabama at Birmingham, Birmingham, Alabama, Unite
| | - Kenneth R Sloan
- Department of Ophthalmology University of Alabama School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States 4Department of Computer and Information Sciences, University of Alabama at Birmingham, Birmingham, Alabama, Unite
| | - Yuhua Zhang
- Department of Ophthalmology University of Alabama School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - K Bailey Freund
- Vitreous Retina Macula Consultants of New York, New York, New York, United States 6Department of Ophthalmology, New York University School of Medicine, New York, New York, United States
| | - Christine A Curcio
- Department of Ophthalmology University of Alabama School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
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VISUALIZING RETINAL PIGMENT EPITHELIUM PHENOTYPES IN THE TRANSITION TO GEOGRAPHIC ATROPHY IN AGE-RELATED MACULAR DEGENERATION. Retina 2017; 36 Suppl 1:S12-S25. [PMID: 28005660 DOI: 10.1097/iae.0000000000001276] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
PURPOSE To inform the interpretation of clinical optical coherence tomography and fundus autofluorescence imaging in geographic atrophy (GA) of age-related macular degeneration by determining the distribution of retinal pigment epithelium (RPE) phenotypes in the transition from health to atrophy in donor eyes. METHODS In RPE-Bruch membrane flat mounts of two GA eyes, the terminations of organized RPE cytoskeleton and autofluorescent material were compared. In high-resolution histological sections of 13 GA eyes, RPE phenotypes were assessed at ±500 and ±100 μm from the descent of the external limiting membrane (ELM) toward Bruch membrane. The ELM descent was defined as curved, reflected, or oblique in shape. Thicknesses of RPE, basal laminar deposit (BLamD), and RPE plus BLamD were measured. RESULTS A border of atrophy that can be precisely delimited is the ELM descent, as opposed to the termination of the RPE layer itself, because of dissociated RPE in the atrophic area. Approaching the ELM descent, the percentage of abnormal RPE morphologies increases, the percentage of age-normal cells decreases, overall RPE thickens, and BLamD does not thin. The combination of RPE plus BLamD is 19.7% thicker at -100 μm from the ELM descent than that at -500 μm (23.1 ± 10.7 μm vs. 19.3 ± 8.2 μm; P = 0.05). CONCLUSION The distribution of RPE phenotypes at the GA transition supports the idea that these morphologies represent defined stages of a degeneration sequence. The idea that RPE dysmorphia including rounding and stacking helps explain variable autofluorescence patterns in GA is supported. The ELM descent and RPE plus BLamD thickness profile may have utility as spectral domain optical coherence tomography metrics in clinical trials.
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VISUALIZING RETINAL PIGMENT EPITHELIUM PHENOTYPES IN THE TRANSITION TO ATROPHY IN NEOVASCULAR AGE-RELATED MACULAR DEGENERATION. Retina 2017; 36 Suppl 1:S26-S39. [PMID: 28005661 DOI: 10.1097/iae.0000000000001330] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PURPOSE To enable future studies of retinal pigment epithelium (RPE) fate in the macular atrophy occurring in eyes with neovascular age-related macular degeneration (nvAMD), the authors determined how RPE morphology changes across the transition from health to atrophy in donor eyes with nvAMD. METHOD In RPE-Bruch membrane flat mounts of 5 nvAMD eyes, the terminations of organized RPE cytoskeleton and autofluorescent material were compared. In high-resolution histologic sections of 27 nvAMD eyes, RPE phenotypes were assessed at ±500 μm and ±100 μm from the descent of the external limiting membrane (ELM) toward the Bruch membrane. Thicknesses of RPE, basal laminar deposit (BLamD), and RPE + BLamD were determined. Shapes of the ELM descent were recorded. RESULTS Approaching the ELM descent, the percentage of different RPE phenotypes and the thickness of RPE, BLamD, and RPE + BLamD each stayed roughly constant. Compared with a separately described cohort of eyes with geographic atrophy, eyes with nvAMD were more likely to have RPE dysmorphia that did not worsen toward the atrophy border, thinner BLamD overall (3.25 ± 3.46 μm vs. 7.99 ± 7.49 μm for geographic atrophy), and a higher proportion of oblique ELM descents (47.9 vs. 31.9%). CONCLUSION The distribution of RPE phenotypes at the transition to macular atrophy in eyes with nvAMD differs from that in primary geographic atrophy, likely reflecting greater photoreceptor loss and the effects of exudation in nvAMD. This distribution, the shape of ELM descents, and thickness profiles may be useful metrics in clinical studies of macular atrophy using optical coherence tomography and fundus autofluorescence.
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Wang W, Townes-Anderson E. LIM Kinase, a Newly Identified Regulator of Presynaptic Remodeling by Rod Photoreceptors After Injury. Invest Ophthalmol Vis Sci 2016; 56:7847-58. [PMID: 26658506 DOI: 10.1167/iovs.15-17278] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
PURPOSE Rod photoreceptors retract their axon terminals and develop neuritic sprouts in response to retinal detachment and reattachment, respectively. This study examines the role of LIM kinase (LIMK), a component of RhoA and Rac pathways, in the presynaptic structural remodeling of rod photoreceptors. METHODS Phosphorylated LIMK (p-LIMK), the active form of LIMK, was examined in salamander retina with Western blot and confocal microscopy. Axon length within the first 7 hours and process growth after 3 days of culture were assessed in isolated rod photoreceptors treated with inhibitors of upstream regulators ROCK and p21-activated kinase (Pak) (Y27632 and IPA-3) and a direct LIMK inhibitor (BMS-5). Porcine retinal explants were also treated with BMS-5 and analyzed 24 hours after detachment. Because Ca2+ influx contributes to axonal retraction, L-type channels were blocked in some experiments with nicardipine. RESULTS Phosphorylated LIMK is present in rod terminals during retraction and in newly formed processes. Axonal retraction over 7 hours was significantly reduced by inhibition of LIMK or its regulators, ROCK and Pak. Process growth was reduced by LIMK or Pak inhibition especially at the basal (axon-bearing) region of the rod cells. Combining Ca2+ channel and LIMK inhibition had no additional effect on retraction but did further inhibit sprouting after 3 days. In detached porcine retina, LIMK inhibition reduced rod axonal retraction and improved retinal morphology. CONCLUSIONS Thus structural remodeling, in the form of either axonal retraction or neuritic growth, requires LIMK activity. LIM kinase inhibition may have therapeutic potential for reducing pathologic rod terminal plasticity after retinal injury.
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Varshney S, Hunter DD, Brunken WJ. Extracellular Matrix Components Regulate Cellular Polarity and Tissue Structure in the Developing and Mature Retina. J Ophthalmic Vis Res 2016; 10:329-39. [PMID: 26730321 PMCID: PMC4687269 DOI: 10.4103/2008-322x.170354] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
While genetic networks and other intrinsic mechanisms regulate much of retinal development, interactions with the extracellular environment shape these networks and modify their output. The present review has focused on the role of one family of extracellular matrix molecules and their signaling pathways in retinal development. In addition to their effects on the developing retina, laminins play a role in maintaining Müller cell polarity and compartmentalization, thereby contributing to retinal homeostasis. This article which is intended for the clinical audience, reviews the fundamentals of retinal development, extracellular matrix organization and the role of laminins in retinal development. The role of laminin in cortical development is also briefly discussed.
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Affiliation(s)
- Shweta Varshney
- Department of Ophthalmology and Cell Biology, SUNY Downstate Medical Center, Brooklyn NY, USA; SUNY Eye Institute, NY, USA
| | - Dale D Hunter
- Department of Ophthalmology and Cell Biology, SUNY Downstate Medical Center, Brooklyn NY, USA; SUNY Eye Institute, NY, USA; Department of Ophthalmology and Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - William J Brunken
- Department of Ophthalmology and Cell Biology, SUNY Downstate Medical Center, Brooklyn NY, USA; SUNY Eye Institute, NY, USA; Department of Ophthalmology and Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, NY, USA
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Fernández-Sánchez L, Lax P, Campello L, Pinilla I, Cuenca N. Astrocytes and Müller Cell Alterations During Retinal Degeneration in a Transgenic Rat Model of Retinitis Pigmentosa. Front Cell Neurosci 2015; 9:484. [PMID: 26733810 PMCID: PMC4686678 DOI: 10.3389/fncel.2015.00484] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 11/30/2015] [Indexed: 12/29/2022] Open
Abstract
Purpose: Retinitis pigmentosa includes a group of progressive retinal degenerative diseases that affect the structure and function of photoreceptors. Secondarily to the loss of photoreceptors, there is a reduction in retinal vascularization, which seems to influence the cellular degenerative process. Retinal macroglial cells, astrocytes, and Müller cells provide support for retinal neurons and are fundamental for maintaining normal retinal function. The aim of this study was to investigate the evolution of macroglial changes during retinal degeneration in P23H rats. Methods: Homozygous P23H line-3 rats aged from P18 to 18 months were used to study the evolution of the disease, and SD rats were used as controls. Immunolabeling with antibodies against GFAP, vimentin, and transducin were used to visualize macroglial cells and cone photoreceptors. Results: In P23H rats, increased GFAP labeling in Müller cells was observed as an early indicator of retinal gliosis. At 4 and 12 months of age, the apical processes of Müller cells in P23H rats clustered in firework-like structures, which were associated with ring-like shaped areas of cone degeneration in the outer nuclear layer. These structures were not observed at 16 months of age. The number of astrocytes was higher in P23H rats than in the SD matched controls at 4 and 12 months of age, supporting the idea of astrocyte proliferation. As the disease progressed, astrocytes exhibited a deteriorated morphology and marked hypertrophy. The increase in the complexity of the astrocytic processes correlated with greater connexin 43 expression and higher density of connexin 43 immunoreactive puncta within the ganglion cell layer (GCL) of P23H vs. SD rat retinas. Conclusions: In the P23H rat model of retinitis pigmentosa, the loss of photoreceptors triggers major changes in the number and morphology of glial cells affecting the inner retina.
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Affiliation(s)
| | - Pedro Lax
- Department of Physiology, Genetics and Microbiology, University of Alicante Alicante, Spain
| | - Laura Campello
- Department of Physiology, Genetics and Microbiology, University of Alicante Alicante, Spain
| | - Isabel Pinilla
- Department of Ophthalmology, Aragon Institute for Health Research, Lozano Blesa University Hospital Zaragoza, Spain
| | - Nicolás Cuenca
- Department of Physiology, Genetics and Microbiology, University of AlicanteAlicante, Spain; Institute Ramón Margalef, University of AlicanteAlicante, Spain
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OUTER RETINAL TUBULATION IN ADVANCED AGE-RELATED MACULAR DEGENERATION: Optical Coherence Tomographic Findings Correspond to Histology. Retina 2015; 35:1339-50. [PMID: 25635579 DOI: 10.1097/iae.0000000000000471] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
PURPOSE To compare optical coherence tomography (OCT) and histology of outer retinal tubulation (ORT) secondary to advanced age-related macular degeneration in patients and in postmortem specimens, with particular attention to the basis of the hyperreflective border of ORT. METHOD A private referral practice (imaging) and an academic research laboratory (histology) collaborated on two retrospective case series. High-resolution OCT raster scans of 43 eyes (34 patients) manifesting ORT secondary to advanced age-related macular degeneration were compared to high-resolution histologic sections through the fovea and superior perifovea of donor eyes (13 atrophic age-related macular degeneration and 40 neovascular age-related macular degeneration) preserved ≤4 hours after death. RESULTS Outer retinal tubulation seen on OCT correlated with histologic findings of tubular structures consisted largely of cones lacking outer segments and lacking inner segments. Four phases of cone degeneration were histologically distinguishable in ORT lumenal walls, nascent, mature, degenerate, and end stage (inner segments and outer segments, inner segments only, no inner segments, and no photoreceptors and only Müller cells forming external limiting membrane, respectively). Mitochondria, which are normally long and bundled within inner segment ellipsoids, were small and scattered within shrunken inner segments and cell bodies of surviving cones. A lumenal border was delimited by an external limiting membrane. Outer retinal tubulation observed in closed and open configurations was distinguishable from cysts and photoreceptor islands on both OCT and histology. Hyperreflective lumenal material seen on OCT represents trapped retinal pigment epithelium and nonretinal pigment epithelium cells. CONCLUSION The defining OCT features of ORT are location in the outer nuclear layer, a hyperreflective band differentiating it from cysts, and retinal pigment epithelium that is either dysmorphic or absent. Histologic and OCT findings of outer retinal tubulation corresponded in regard to composition, location, shape, and stages of formation. The reflectivity of ORT lumenal walls on OCT apparently does not require an outer segment or an inner/outer segment junction, indicating an independent reflectivity source, possibly mitochondria, in the inner segments.
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Ross DH, Clark ME, Godara P, Huisingh C, McGwin G, Owsley C, Litts KM, Spaide RF, Sloan KR, Curcio CA. RefMoB, a Reflectivity Feature Model-Based Automated Method for Measuring Four Outer Retinal Hyperreflective Bands in Optical Coherence Tomography. Invest Ophthalmol Vis Sci 2015; 56:4166-76. [PMID: 26132776 PMCID: PMC4495810 DOI: 10.1167/iovs.14-15256] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 03/10/2015] [Indexed: 12/20/2022] Open
Abstract
PURPOSE To validate a model-driven method (RefMoB) of automatically describing the four outer retinal hyperreflective bands revealed by spectral-domain optical coherence tomography (SDOCT), for comparison with histology of normal macula; to report thickness and position of bands, particularly band 2 (ellipsoid zone [EZ], commonly called IS/OS). METHODS Foveal and superior perifoveal scans of seven SDOCT volumes of five individuals aged 28 to 69 years with healthy maculas were used (seven eyes for validation, five eyes for measurement). RefMoB determines band thickness and position by a multistage procedure that models reflectivities as a summation of Gaussians. Band thickness and positions were compared with those obtained by manual evaluators for the same scans, and compared with an independent published histological dataset. RESULTS Agreement among manual evaluators was moderate. Relative to manual evaluation, RefMoB reported reduced thickness and vertical shifts in band positions in a band-specific manner for both simulated and empirical data. In foveal and perifoveal scans, band 1 was thick relative to the anatomical external limiting membrane, band 2 aligned with the outer one-third of the anatomical IS ellipsoid, and band 3 (IZ, interdigitation of retinal pigment epithelium and photoreceptors) was cleanly delineated. CONCLUSIONS RefMoB is suitable for automatic description of the location and thickness of the four outer retinal hyperreflective bands. Initial results suggest that band 2 aligns with the outer ellipsoid, thus supporting its recent designation as EZ. Automated and objective delineation of band 3 will help investigations of structural biomarkers of dark-adaptation changes in aging.
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Affiliation(s)
- Douglas H. Ross
- Department of Computer and Information Sciences University of Alabama at Birmingham, Birmingham, Alabama, United States
- Department of Mechanical Engineering, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Mark E. Clark
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Pooja Godara
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Carrie Huisingh
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Gerald McGwin
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, Alabama, United States
- Department of Epidemiology, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Cynthia Owsley
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Katie M. Litts
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, Alabama, United States
- Vision Science Graduate Program, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Richard F. Spaide
- Vitreous Retina Macula Consultants of New York, New York, New York, United States
| | - Kenneth R. Sloan
- Department of Computer and Information Sciences University of Alabama at Birmingham, Birmingham, Alabama, United States
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Christine A. Curcio
- Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, Alabama, United States
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Lee W, Nõupuu K, Oll M, Duncker T, Burke T, Zernant J, Bearelly S, Tsang SH, Sparrow JR, Allikmets R. The external limiting membrane in early-onset Stargardt disease. Invest Ophthalmol Vis Sci 2014; 55:6139-49. [PMID: 25139735 DOI: 10.1167/iovs.14-15126] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
PURPOSE To describe pathologic changes of the external limiting membrane (ELM) in young patients with early-onset Stargardt (STGD1) disease. METHODS Twenty-six STGD1 patients aged younger than 20 years with confirmed disease-causing adenosine triphosphate-binding cassette, subfamily A, member 4 (ABCA4) alleles and 30 age-matched unaffected individuals were studied. Spectral-domain optical coherence tomography (SD-OCT), fundus autofluorescence (AF), and color fundus photography (CFP) images, as well as full-field electroretinograms were obtained and analyzed for one to four visits in each patient. RESULTS The ELM in all patients exhibited a distinct thickening that was not observed in unaffected individuals. In addition, accumulations of reflective deposits were noted in the outer nuclear layer in every patient. Four patients exhibited a concave protuberance or bulging of a thickened and hyperreflective ELM band within the fovea containing preserved photoreceptors. Longitudinal SD-OCT data in several patients revealed the persistence of this ELM abnormality over a period of time (1-4 years). Furthermore, the edges of the inner segment ellipsoid band appeared to recede earlier than the ELM band in active lesions. CONCLUSIONS Structural changes seen in the ELM of this cohort may reflect a gliotic response to cellular stress at the photoreceptor level in early-onset STGD1.
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Affiliation(s)
- Winston Lee
- Department of Ophthalmology, Columbia University, New York, New York, United States
| | - Kalev Nõupuu
- Department of Ophthalmology, Columbia University, New York, New York, United States Eye Clinic, Tartu University Hospital, Tartu, Estonia
| | - Maris Oll
- Department of Ophthalmology, Columbia University, New York, New York, United States Eye Clinic, Tartu University Hospital, Tartu, Estonia
| | - Tobias Duncker
- Department of Ophthalmology, Columbia University, New York, New York, United States
| | - Tomas Burke
- Department of Ophthalmology, Royal United Hospital, Bath, United Kingdom
| | - Jana Zernant
- Department of Ophthalmology, Columbia University, New York, New York, United States
| | - Srilaxmi Bearelly
- Department of Ophthalmology, Columbia University, New York, New York, United States
| | - Stephen H Tsang
- Department of Ophthalmology, Columbia University, New York, New York, United States Department of Pathology & Cell Biology, Columbia University, New York, New York, United States
| | - Janet R Sparrow
- Department of Ophthalmology, Columbia University, New York, New York, United States Department of Pathology & Cell Biology, Columbia University, New York, New York, United States
| | - Rando Allikmets
- Department of Ophthalmology, Columbia University, New York, New York, United States Department of Pathology & Cell Biology, Columbia University, New York, New York, United States
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Knockdown of zebrafish blood vessel epicardial substance results in incomplete retinal lamination. ScientificWorldJournal 2014; 2014:803718. [PMID: 24741362 PMCID: PMC3972863 DOI: 10.1155/2014/803718] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 01/29/2014] [Indexed: 01/21/2023] Open
Abstract
Cell polarity during eye development determines the normal retinal lamination and differentiation of photoreceptor cells in the retina. In vertebrates, blood vessel epicardial substance (Bves) is known to play an important role in the formation and maintenance of the tight junctions essential for epithelial cell polarity. In the current study, we generated a transgenic zebrafish Bves (zbves) promoter-EGFP zebrafish line to investigate the expression pattern of Bves in the retina and to study the role of zbves in retinal lamination. Immunostaining with different specific antibodies from retinal cells and transmission electron microscopy were used to identify the morphological defects in normal and Bves knockdown zebrafish. In normal zebrafish, Bves is located at the apical junctions of embryonic retinal neuroepithelia during retinogenesis; later, it is strongly expressed around inner plexiform layer (IPL) and retinal pigment epithelium (RPE). In contrast, a loss of normal retinal lamination and cellular polarity was found with undifferentiated photoreceptor cells in Bves knockdown zebrafish. Herein, our results indicated that disruption of Bves will result in a loss of normal retinal lamination.
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Cordovez JA, Traboulsi EI, Capasso JE, Sadagopan KA, Ganesh A, Rychwalski PJ, Neely KA, Brodie SE, Levin AV. Retinal Dystrophy with Intraretinal Cystoid Spaces Associated with Mutations in the Crumbs Homologue (CRB1) Gene. Ophthalmic Genet 2014; 36:257-64. [DOI: 10.3109/13816810.2014.881505] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Raymond PA, Colvin SM, Jabeen Z, Nagashima M, Barthel LK, Hadidjojo J, Popova L, Pejaver VR, Lubensky DK. Patterning the cone mosaic array in zebrafish retina requires specification of ultraviolet-sensitive cones. PLoS One 2014; 9:e85325. [PMID: 24465536 PMCID: PMC3897441 DOI: 10.1371/journal.pone.0085325] [Citation(s) in RCA: 36] [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: 08/05/2013] [Accepted: 11/25/2013] [Indexed: 12/17/2022] Open
Abstract
Cone photoreceptors in teleost fish are organized in precise, crystalline arrays in the epithelial plane of the retina. In zebrafish, four distinct morphological/spectral cone types occupy specific, invariant positions within a regular lattice. The cone lattice is aligned orthogonal and parallel to circumference of the retinal hemisphere: it emerges as cones generated in a germinal zone at the retinal periphery are incorporated as single-cell columns into the cone lattice. Genetic disruption of the transcription factor Tbx2b eliminates most of the cone subtype maximally sensitive to ultraviolet (UV) wavelengths and also perturbs the long-range organization of the cone lattice. In the tbx2b mutant, the other three cone types (red, green, and blue cones) are specified in the correct proportion, differentiate normally, and acquire normal, planar polarized adhesive interactions mediated by Crumbs 2a and Crumbs 2b. Quantitative image analysis of cell adjacency revealed that the cones in the tbx2b mutant primarily have two nearest neighbors and align in single-cell-wide column fragments that are separated by rod photoreceptors. Some UV cones differentiate at the dorsal retinal margin in the tbx2b mutant, although they are severely dysmorphic and are eventually eliminated. Incorporating loss of UV cones during formation of cone columns at the margin into our previously published mathematical model of zebrafish cone mosaic formation (which uses bidirectional interactions between planar cell polarity proteins and anisotropic mechanical stresses in the plane of the retinal epithelium to generate regular columns of cones parallel to the margin) reproduces many features of the pattern disruptions seen in the tbx2b mutant.
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Affiliation(s)
- Pamela A. Raymond
- Department of Molecular, Cellular, and Developmental Biology, College of Literature, Science, and the Arts, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail: (PAR); (DKL)
| | - Steven M. Colvin
- Department of Molecular, Cellular, and Developmental Biology, College of Literature, Science, and the Arts, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Zahera Jabeen
- Department of Physics, College of Literature, Science, and the Arts, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Mikiko Nagashima
- Department of Molecular, Cellular, and Developmental Biology, College of Literature, Science, and the Arts, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Linda K. Barthel
- Department of Molecular, Cellular, and Developmental Biology, College of Literature, Science, and the Arts, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Jeremy Hadidjojo
- Department of Physics, College of Literature, Science, and the Arts, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Lilia Popova
- Department of Molecular, Cellular, and Developmental Biology, College of Literature, Science, and the Arts, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Vivek R. Pejaver
- Department of Molecular, Cellular, and Developmental Biology, College of Literature, Science, and the Arts, University of Michigan, Ann Arbor, Michigan, United States of America
| | - David K. Lubensky
- Department of Physics, College of Literature, Science, and the Arts, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail: (PAR); (DKL)
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Randlett O, Norden C, Harris WA. The vertebrate retina: a model for neuronal polarization in vivo. Dev Neurobiol 2011; 71:567-83. [PMID: 21557506 DOI: 10.1002/dneu.20841] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The vertebrate retina develops rapidly from a proliferative neuroepithelium into a highly ordered laminated structure, with five distinct neuronal cell types. Like all neurons, these cells need to polarize in appropriate orientations order integrate their neuritic connections efficiently into functional networks. Its relative simplicity, amenability to in vivo imaging and experimental manipulation, as well as the opportunity to study varied cell types within a single tissue, make the retina a powerful model to uncover how neurons polarize in vivo. Here we review the progress that has been made thus far in understanding how the different retinal neurons transform from neuroepithelial cells into mature neurons, and how the orientation of polarization may be specified by a combination of pre-established intrinsic cellular polarity set up within neuroepithelial cells, and extrinsic cues acting upon these differentiating neurons.
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Affiliation(s)
- Owen Randlett
- Department of Physiology, Development and Neuroscience, Cambridge University, Downing Street, Cambridge, United Kingdom
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Karlsen OA, Bjørneklett S, Berg K, Brattås M, Bohne-Kjersem A, Grøsvik BE, Goksøyr A. Integrative environmental genomics of Cod (Gadus morhua): the proteomics approach. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2011; 74:494-507. [PMID: 21391094 DOI: 10.1080/15287394.2011.550559] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Atlantic cod (Gadus morhua) is an essential species in North Atlantic fisheries and increasingly relevant as an aquaculture species. However, potential conflicts with both coastal industry and petroleum industry expanding into northern waters make it important to understand how effluents (produced water, pharmaceuticals, food contaminants, and feed contaminants) affect the growth, reproduction, and health of this species in order to maintain a sustainable cod population and a healthy human food source, and to discover biomarkers for environmental monitoring and risk assessment. The ongoing genome sequencing effort of Atlantic cod has opened the possibility for a systems biology approach to elucidate molecular mechanisms of toxicity. Our study aims to be a first step toward such a systems toxicology understanding of genomic responses to environmental insults. A toxicogenomic approach was initiated that is combining data generated from proteomics analyses and transcriptomics analyses, and the concurrent development of searchable expressed sequence tags (EST) databases and genomic databases. This interdisciplinary study may also open new possibilities of gene annotation and pathway analyses.
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Mamczur P, Mazurek J, Rakus D. Ubiquitous presence of gluconeogenic regulatory enzyme, fructose-1,6-bisphosphatase, within layers of rat retina. Cell Tissue Res 2010; 341:213-21. [PMID: 20614135 PMCID: PMC2914254 DOI: 10.1007/s00441-010-1008-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Accepted: 06/14/2010] [Indexed: 01/29/2023]
Abstract
To shed some light on gluconeogenesis in mammalian retina, we have focused on fructose-1,6-bisphosphatase (FBPase), a regulatory enzyme of the process. The abundance of the enzyme within the layers of the rat retina suggests that, in mammals in contrast to amphibia, gluconeogenesis is not restricted to one specific cell of the retina. We propose that FBPase, in addition to its gluconeogenic role, participates in the protection of the retina against reactive oxygen species. Additionally, the nuclear localization of FBPase and of its binding partner, aldolase, in the retinal cells expressing the proliferation marker Ki-67 indicates that these two gluconeogenic enzymes are involved in non-enzymatic nuclear processes.
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Affiliation(s)
- Piotr Mamczur
- Department of Animal Molecular Physiology, Institute of Zoology, Wroclaw University, Cybulskiego 30, 50-205, Wroclaw, Poland
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Omri S, Omri B, Savoldelli M, Jonet L, Thillaye-Goldenberg B, Thuret G, Gain P, Jeanny JC, Crisanti P, Behar-Cohen F. The outer limiting membrane (OLM) revisited: clinical implications. Clin Ophthalmol 2010; 4:183-95. [PMID: 20463783 PMCID: PMC2861922 DOI: 10.2147/opth.s5901] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Purpose The outer limiting membrane (OLM) is considered to play a role in maintaining the structure of the retina through mechanical strength. However, the observation of junction proteins located at the OLM and its barrier permeability properties may suggest that the OLM may be part of the retinal barrier. Material and methods Normal and diabetic rat, monkey, and human retinas were used to analyze junction proteins at the OLM. Proteome analyses were performed using immunohistochemistry on sections and flat-mounted retinas and western blotting on protein extracts obtained from laser microdissection of the photoreceptor layers. Semi-thin and ultrastructure analyses were also reported. Results In the rat retina, in the subapical region zonula occludens-1 (ZO-1), junction adhesion molecule (JAM), an atypical protein kinase C, is present and the OLM shows dense labeling of occludin, JAM, and ZO-1. The presence of occludin has been confirmed using western blot analysis of the microdissected OLM region. In diabetic rats, occludin expression is decreased and glial cells junctions are dissociated. In the monkey retina, occludin, JAM, and ZO-1 are also found in the OLM. Junction proteins have a specific distribution around cone photoreceptors and Müller glia. Ultrastructural analyses suggest that structures like tight junctions may exist between retinal glial Müller cells and photoreceptors. Conclusions In the OLM, heterotypic junctions contain proteins from both adherent and tight junctions. Their structure suggests that tight junctions may exist in the OLM. Occludin is present in the OLM of the rat and monkey retina and it is decreased in diabetes. The OLM should be considered as part of the retinal barrier that can be disrupted in pathological conditions contributing to fluid accumulation in the macula.
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Affiliation(s)
- S Omri
- INSERM, U872 Physiopathology of ocular diseases: Therapeutic innovations, Paris, France
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Bohne-Kjersem A, Bache N, Meier S, Nyhammer G, Roepstorff P, Saele O, Goksøyr A, Grøsvik BE. Biomarker candidate discovery in Atlantic cod (Gadus morhua) continuously exposed to North Sea produced water from egg to fry. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2010; 96:280-289. [PMID: 20031237 DOI: 10.1016/j.aquatox.2009.11.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Revised: 11/03/2009] [Accepted: 11/08/2009] [Indexed: 05/28/2023]
Abstract
In this study Atlantic cod (Gadus morhua) were exposed to different levels of North Sea produced water (PW) and 17beta-oestradiol (E(2)), a natural oestrogen, from egg to fry stage (90 days). By comparing changes in protein expression following E(2) exposure to changes induced by PW treatment, we were able to compare the induced changes by PW to the mode of action of oestrogens. Changes in the proteome in response to exposure in whole cod fry (approximately 80 days post-hatching, dph) were detected by two-dimensional gel electrophoresis and image analysis and identified by MALDI-ToF-ToF mass spectrometry, using a newly developed cod EST database and the NCBI database. Many of the protein changes occurred at low levels (0.01% and 0.1% PW) of exposure, indicating putative biological responses at lower levels than previously detected. Using discriminant analysis, we identified a set of protein changes that may be useful as biomarker candidates of produced water (PW) and oestradiol exposure in Atlantic cod fry. The biomarker candidates discovered in this study may, following validation, prove effective as diagnostic tools in monitoring exposure and effects of discharges from the petroleum industry offshore, aiding future environmental risk analysis and risk management.
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Affiliation(s)
- Anneli Bohne-Kjersem
- Department of Molecular Biology, University of Bergen, PB 7800, N-5020 Bergen, Norway.
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Kennedy B, Malicki J. What drives cell morphogenesis: a look inside the vertebrate photoreceptor. Dev Dyn 2009; 238:2115-38. [PMID: 19582864 DOI: 10.1002/dvdy.22010] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Vision mediating photoreceptor cells are specialized light-sensitive neurons in the outer layer of the vertebrate retina. The human retina contains approximately 130 million of such photoreceptors, which enable images of the external environment to be captured at high resolution and high sensitivity. Rod and cone photoreceptor subtypes are further specialized for sensing light in low and high illumination, respectively. To enable visual function, these photoreceptors have developed elaborate morphological domains for the detection of light (outer segments), for changing cell shape (inner segments), and for communication with neighboring retinal neurons (synaptic terminals). Furthermore, rod and cone subtypes feature unique morphological variations of these specialized characteristics. Here, we review the major aspects of vertebrate photoreceptor morphology and key genetic mechanisms that drive their formation. These mechanisms are necessary for cell differentiation as well as function. Their defects lead to cell death.
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Affiliation(s)
- Breandán Kennedy
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Belfield, Dublin, Ireland.
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Reidel B, Goldmann T, Giessl A, Wolfrum U. The translocation of signaling molecules in dark adapting mammalian rod photoreceptor cells is dependent on the cytoskeleton. ACTA ACUST UNITED AC 2008; 65:785-800. [PMID: 18623243 DOI: 10.1002/cm.20300] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
In vertebrate rod photoreceptor cells, arrestin and the visual G-protein transducin move between the inner segment and outer segment in response to changes in light. This stimulus dependent translocation of signalling molecules is assumed to participate in long term light adaptation of photoreceptors. So far the cellular basis for the transport mechanisms underlying these intracellular movements remains largely elusive. Here we investigated the dependency of these movements on actin filaments and the microtubule cytoskeleton of photoreceptor cells. Co-cultures of mouse retina and retinal pigment epithelium were incubated with drugs stabilizing and destabilizing the cytoskeleton. The actin and microtubule cytoskeleton and the light dependent distribution of signaling molecules were subsequently analyzed by light and electron microscopy. The application of cytoskeletal drugs differentially affected the cytoskeleton in photoreceptor compartments. During dark adaptation the depolymerization of microtubules as well as actin filaments disrupted the translocation of arrestin and transducin in rod photoreceptor cells. During light adaptation only the delivery of arrestin within the outer segment was impaired after destabilization of microtubules. Movements of transducin and arrestin required intact cytoskeletal elements in dark adapting cells. However, diffusion might be sufficient for the fast molecular movements observed as cells adapt to light. These findings indicate that different molecular translocation mechanisms are responsible for the dark and light associated translocations of arrestin and transducin in rod photoreceptor cells.
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Affiliation(s)
- Boris Reidel
- Department of Cell and Matrix Biology, Institute of Zoology, Johannes Gutenberg University of Mainz, Germany
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West EL, Pearson RA, Tschernutter M, Sowden JC, MacLaren RE, Ali RR. Pharmacological disruption of the outer limiting membrane leads to increased retinal integration of transplanted photoreceptor precursors. Exp Eye Res 2008; 86:601-11. [PMID: 18294631 PMCID: PMC2394572 DOI: 10.1016/j.exer.2008.01.004] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2007] [Revised: 12/21/2007] [Accepted: 01/03/2008] [Indexed: 11/27/2022]
Abstract
Retinal degeneration is the leading cause of untreatable blindness in the developed world. Cell transplantation strategies provide a novel therapeutic approach to repair the retina and restore sight. Previously, we have shown that photoreceptor precursor cells can integrate and form functional photoreceptors after transplantation into the subretinal space of the adult mouse. In a clinical setting, however, it is likely that far greater numbers of integrated photoreceptors would be required to restore visual function. We therefore sought to assess whether the outer limiting membrane (OLM), a natural barrier between the subretinal space and the outer nuclear layer (ONL), could be reversibly disrupted and if disruption of this barrier could lead to enhanced numbers of transplanted photoreceptors integrating into the ONL. Transient chemical disruption of the OLM was induced in adult mice using the glial toxin, dl-alpha-aminoadipic acid (AAA). Dissociated early post-natal neural retinal cells were transplanted via subretinal injection at various time-points after AAA administration. At 3 weeks post-injection, the number of integrated, differentiated photoreceptor cells was assessed and compared with those found in the PBS-treated contralateral eye. We demonstrate for the first time that the OLM can be reversibly disrupted in adult mice, using a specific dose of AAA administered by intravitreal injection. In this model, OLM disruption is maximal at 72 h, and recovers by 2 weeks. When combined with cell transplantation, disruption of the OLM leads to a significant increase in the number of photoreceptors integrated within the ONL compared with PBS-treated controls. This effect was only seen in animals in which AAA had been administered 72 h prior to transplantation, i.e. when precursor cells were delivered into the subretinal space at a time coincident with maximal OLM disruption. These findings suggest that the OLM presents a physical barrier to photoreceptor integration following transplantation into the subretinal space in the adult mouse. Reversible disruption of the OLM may provide a strategy for increasing cell integration in future therapeutic applications.
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Affiliation(s)
- E L West
- Division of Molecular Therapy, University College London, Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
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DANIELE LAURENL, ADAMS RALFH, DURANTE DIANEE, PUGH EDWARDN, PHILP NANCYJ. Novel distribution of junctional adhesion molecule-C in the neural retina and retinal pigment epithelium. J Comp Neurol 2008; 505:166-76. [PMID: 17853450 PMCID: PMC3144860 DOI: 10.1002/cne.21489] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Junction adhesion molecules-A, -B, and -C (Jams) are cell surface glycoproteins that have been shown to play an important role in the assembly and maintenance of tight junctions and in the establishment of epithelial cell polarity. Recent studies reported that Jam-C mRNA was increased threefold in the all-cone retina of the Nrl(-/-) mouse, suggesting that Jam-C is required for maturation and polarization of cone photoreceptors cells. We examined the expression of Jams in the mouse retina by using confocal immunofluorescence localization. Jam-C was detected in tight junctions of retinal pigment epithelium (RPE) and at the outer limiting membrane (OLM) in the specialized adherens junctions between Müller and photoreceptor cells. Additionally, Jam-C labeling was observed in the long apical processes of Müller and RPE cells that extend between the inner segments and outer segments of photoreceptors, respectively. Jam-B was also detected at the OLM. In the developing retina, Jam-B and -C were detected at the apical junctions of embryonic retinal neuroepithelia, suggesting a role for Jams in retinogenesis. In eyes from Jam-C(-/-) mice, retinal lamination, polarity, and photoreceptor morphology appeared normal. Although Jam-A was not detected at the OLM in wild-type retinas, it was present at the OLM in retinas of Jam-C(-/-) mice. These findings indicate that up-regulation of Jam-A in the retina compensates for the loss of Jam-C. The nonclassical distribution of Jam-C in the apical membranes of Müller cells and RPE suggests that Jam-C has a novel function in the retina.
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Affiliation(s)
- LAUREN L. DANIELE
- F.M. Kirby Center for Molecular Ophthalmology, Department of Ophthalmology, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - RALF H. ADAMS
- Vascular Development Laboratory, Cancer Research UK London Research Institute, London WC2A3PX, United Kingdom
| | - DIANE E. DURANTE
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
| | - EDWARD N. PUGH
- F.M. Kirby Center for Molecular Ophthalmology, Department of Ophthalmology, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - NANCY J. PHILP
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
- Correspondence to: Nancy J. Philp, Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107.
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Isiksoy S, Basmak H, Kasapoglu Dundar E, Ozer A. Expression of proteins associated with cell-matrix adhesion in proliferative vitreoretinopathy designed by Dispase model. Eur J Ophthalmol 2007; 17:89-103. [PMID: 17294388 DOI: 10.1177/112067210701700113] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
PURPOSE During recent years, the interaction of cell surface molecule, extracellular matrix proteins, and cytoskeletal elements has been a topic for research for the purpose of understanding the mechanisms of pathologic conditions. This study aims to evaluate the expression of CD44, as a cell surface adhesion molecule; fibronectin (FN), as an extracellular and a cell surface protein; vinculin and actin/á-smooth muscle actin (alfa-SMA), as cytoskeletal elements; and the interactions of these proteins in the microenvironment of proliferative vitreoretinopathy (PVR). METHODS This experimental study was designed by the intravitreal Dispase model in rabbits and proteins' expression were evaluated via immunohistochemical staining. RESULTS As a cell surface protein, CD44 expression was determined in only four eyes focally and weakly, but in a small number of cells. Among the cytoskeletal proteins, vinculin expression was the most extensive and the strongest in intensity in epi- and subretinal membranes. Alpha-SMA expression was mostly present within small foci of cells. Fibronectin expression was determined in some of the eyes only faintly. CONCLUSIONS Vinculin seems to be involved in PVR pathogenesis. Variability in co-distribution of the expression of vinculin, FN, and alfa-SMA reflects the dynamic interactions evolving between cell and extracellular matrix during the epi- and subretinal membrane formations. The results of this study were determined not to be in support of the assumption that CD44 has a functional role in the pathogenesis of PVR.
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Affiliation(s)
- S Isiksoy
- Department of Pathology, School of Medicine, Eskisehir Osmangazi University, Eskisehir, Turkey
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Hsu YC, Willoughby JJ, Christensen AK, Jensen AM. Mosaic Eyes is a novel component of the Crumbs complex and negatively regulates photoreceptor apical size. Development 2006; 133:4849-59. [PMID: 17092952 PMCID: PMC2836018 DOI: 10.1242/dev.02685] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Establishment of apical-basal cell polarity has emerged as an important process during development, and the Crumbs complex is a major component of this process in Drosophila. By comparison, little is known about the role of Crumbs (Crb) proteins in vertebrate development. We show that the FERM protein Mosaic Eyes (Moe) is a novel regulatory component of the Crumbs complex. Moe coimmunoprecipitates with Ome/Crb2a and Nok (Pals1) from adult eye and in vitro interaction experiments suggest these interactions are direct. Morpholino knockdown of ome/crb2a phenocopies the moe mutations. Moe and Crumbs proteins colocalize apically and this apical localization requires reciprocal protein function. By performing genetic mosaic analyses, we show that moe- rod photoreceptors have greatly expanded apical structures, suggesting that Moe is a negative regulator of Crumbs protein function in photoreceptors. We propose that Moe is a crucial regulator of Crumbs protein cell-surface abundance and localization in embryos.
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Affiliation(s)
- Ya-Chu Hsu
- Department of Biology, University of Massachusetts, Amherst, MA 01003, USA
- Molecular and Cellular Biology Program, University of Massachusetts, Amherst, MA 01003, USA
| | - John J. Willoughby
- Department of Biology, University of Massachusetts, Amherst, MA 01003, USA
| | - Arne K. Christensen
- Department of Biology, University of Massachusetts, Amherst, MA 01003, USA
- Molecular and Cellular Biology Program, University of Massachusetts, Amherst, MA 01003, USA
| | - Abbie M. Jensen
- Department of Biology, University of Massachusetts, Amherst, MA 01003, USA
- Molecular and Cellular Biology Program, University of Massachusetts, Amherst, MA 01003, USA
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40
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Xi Q, Pauer GJT, Marmorstein AD, Crabb JW, Hagstrom SA. Tubby-like protein 1 (TULP1) interacts with F-actin in photoreceptor cells. Invest Ophthalmol Vis Sci 2006; 46:4754-61. [PMID: 16303976 PMCID: PMC3026440 DOI: 10.1167/iovs.05-0693] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE TULP1 is a photoreceptor-specific protein of unknown function that, when mutated, can cause retinitis pigmentosa in humans and photoreceptor degeneration in mice. Toward a better understanding of the role of TULP1 in retinal disease, its subcellular localization was sought and the TULP1 protein binding partners identified. METHODS Immunocytochemistry and subcellular fractionation were used to determine the localization of TULP1 and actin in COS7 cells and photoreceptor cells. Immunoprecipitation from retinal lysates followed by liquid chromatography tandem mass spectrometry and in vitro binding assays was used to identify TULP1-binding partners. Phospholipid binding assays were performed with a commercially available kit. RESULTS TULP1 localizes at or near the plasma membrane and associates with the membranous fraction of COS7 cells, probably through binding phosphorylated phospholipids. In addition, TULP1 partitions to the aqueous phase during Triton X-114 extraction. Immunoprecipitation from retinal lysate identified F-actin as a possible TULP1-binding partner. Co-sedimentation assays further support an interaction between TULP1 and actin. In photoreceptor cells, actin and TULP1 colocalize at the inner segment, connecting cilium, and outer limiting membrane. CONCLUSIONS TULP1 is a cytoplasmic protein that associates with cellular membranes and the cytoskeleton. TULP1 and actin appear to interact and colocalize in photoreceptor cells of the retina. TULP1 may be involved in actin cytoskeletal functions such as protein trafficking that takes place at or near the plasma membrane from the inner segment through the connecting cilium into the outer segment of photoreceptor cells.
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Affiliation(s)
- Quansheng Xi
- Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio
| | | | - Alan D. Marmorstein
- Department of Ophthalmology and Vision Science, University of Arizona, Tucson, Arizona
| | - John W. Crabb
- Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio
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41
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Lemmers C, Médina E, Lane-Guermonprez L, Arsanto JP, Le Bivic A. Rôle des protéines Crumbs dans le contrôle de la morphogenèse des cellules épithéliales et des photorécepteurs. Med Sci (Paris) 2004; 20:663-7. [PMID: 15329816 DOI: 10.1051/medsci/2004206-7663] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Degeneration of retina can have many causes and among the genes involved, CRB1 has been shown to be associated with Retinitis pigmentosa (RP) group 12 and Leber congenital amaurosis (LCA), two dramatic pathologies in young patients. CRB1 belongs to a family of genes conserved from Caenorhabditis elegans to human. In Drosophila melanogaster, for example, crb is essential both for the formation of the adherens junctions in epithelial cells of ectodermal origin during gastrulation and for the morphogenesis of photoreceptors in the eye. Crumbs is a transmembrane protein with a short cytoplasmic domain that interacts with scaffold proteins, Stardust and Discs lost, and with the apical cytoskeleton made of moesin and betaheavy-spectrin. The extracellular domain of Crumbs is essential for its function in photoreceptors but so far there are no known proteins interacting with it. In human, there are three known crb homologues, CRB1, 2 and 3, and CRB1 is expressed in the retina and localizes to the adherens junctions of the rods. Based on the model drawn from Drosophila, CRB1 could be involved in maintaining the morphology of rods to ensure a normal function of the retina. This is supported by the fact that the homologues of the known partners of Crumbs are also conserved in human and expressed in the retina. Understanding the precise molecular mechanism by which CRB1 acts will help to find new therapies for patients suffering from RP12 and LCA.
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Affiliation(s)
- Céline Lemmers
- UMR 6156, Laboratoire de neurogenèse et morphogenèse au cours du développement et chez l'adulte (NMDA), IBDM, Campus de Luminy, Case 907. 13288 Marseille Cedex 09. France
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42
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Winkler J, Hagelstein S, Rohde M, Laqua H. Cellular and cytoskeletal dynamics within organ cultures of porcine neuroretina. Exp Eye Res 2002; 74:777-88. [PMID: 12126951 DOI: 10.1006/exer.2002.1188] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of this study was to establish a retinal organ culture and to follow the cellular and cytoskeletal changes. For this purpose the authors detached porcine neuroretinas from the underlying pigment epithelium, and incubated them for 2 weeks under standardized conditions. After 3, 6, 10, and 13 days in culture the retinal tissues were fixed, embedded in LR-White resin or paraffin wax and processed for electron-, light-, immunofluorescence- and confocal laser scanning microscopy. Antibodies directed against alpha-tubulin, actin, glial fibrillary acidic protein (GFAP), vimentin, neurofilament(200) and beta-catenin were used to investigate the cytoskeletal changes over a certain period of time. After experimental detachment Müller cells quickly started to hypertrophy showing increased levels of intermediate filaments (i.e. vimentin and GFAP). The actin labelling of photoreceptor cells decreased concomitantly with a rapid degeneration of the outer segments. After 1 week of detachment the Müller cell cytoplasm revealed increasing amounts of actin and tubulin staining. Actin filaments appeared frequently organized in thick bundles across the full width of the retina, whereas increasing levels of tubulin shifted into the outer nuclear region especially concentrated near the outer limiting membrane. A prolonged time of explant culturing resulted in a discontinuous staining of beta-catenin along the adherent junctions of the outer limiting membrane, followed by an outgrowth of Müller cell extensions into the subretinal space. Double staining of tubulin and cones showed that this outgrowth predominantly occurred between cone inner segments. The outer limiting membrane was penetrated by stalk-like structures, highly enriched with tubulin and associated with swollen tips, reaching into the subretina. Electron microscopy demonstrated in detail the focal disruption of the outer limiting membrane by Müller cell extensions and subsequent subretinal gliosis. The cytoskeletal reactions described here were compared with degenerative changes observed after induced retinal detachments.
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Affiliation(s)
- Jörg Winkler
- Department of Experimental Ophthalmology, Medical University of Lübeck, D-23538, Lübeck, Germany.
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43
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Abstract
Retinitis pigmentosa (RP) constitutes a group of genetically mediated, degenerative retinal diseases that display a broad range of phenotypes. There is appreciable heterogeneity in the pathogenetic mechanisms that underlie the various forms of RP, but a substantial percentage of the known cases arise as a consequence of mutations in rhodopsin or other rod-specific proteins. However, despite the fact that the genetic defect is expressed solely in the rod photoreceptors, otherwise healthy cone photoreceptors invariably die, resulting in severe visual impairment. In this paper, the author proposes a mechanism that may be responsible, at least in part, for this unfortunate circumstance. The basic premise of the hypothesis is that the spread of the disease from dying rods to genetically normal cones is a form of 'bystander' effect, mediated by the gap junctions that exist between these photoreceptor subtypes. On this view, agents that trigger the apoptotic process permeate the intercellular gap-junctional channels to carry the disease from rods to neighboring cones. If permeation of noxious substances through gap junctions is a significant factor in the non-cell-autonomous spread of photoreceptor degeneration, blocking transmission through these channels may provide a means for therapeutic intervention. Many substances are known to block gap-junctional communication, but if the rod-cone channel is to be targeted, it will be essential to identify the connexins that form the gap junctions between the two types of photoreceptor, and to develop drugs that selectively affect their junctional properties. Clearly, passage of toxic agents through gap junctions may not be the only form of cell-cell interaction by which dying rods could cause cone cell death, and in this brief account, the author considers other avenues that are currently being explored to explain this phenomenon.
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Affiliation(s)
- Harris Ripps
- Lions of Illinois Eye Research Institute, Department of Ophthalmology and Visual Sciences, Chicago, IL 60612, USA.
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44
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Baumann O. Distribution of nonmuscle myosin-II in honeybee photoreceptors and its possible role in maintaining compound eye architecture. J Comp Neurol 2001; 435:364-78. [PMID: 11406818 DOI: 10.1002/cne.1036] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Photoreceptor and accessory cells in the insect compound eye exhibit a characteristic architecture, probably established and maintained by the contribution of membrane-associated cytoskeletal elements. The present study identifies and localizes nonmuscle myosin-II in honeybee photoreceptors by use of an affinity-purified antibody against scallop muscle myosin-II heavy chain (MHC). Western blot analysis and immunofluorescence staining confirmed cross-reactivity of the antibody with honeybee muscle MHC. In the compound eye, the antibody identified a protein that comigrated with muscle MHC on sodium dodecylsulfate-polyacrylamide gels. Association with the cytoskeleton, ATP-dependent binding to exogenous actin filaments, and cross-reactivity with several other antibodies against MHC, including an antibody to Drosophila nonmuscle MHC, support the conclusion that the cross-reacting protein represents nonmuscle MHC. Confocal immunofluorescence microscopy on honeybee eyes showed that the motor protein was highly enriched at distinct regions of the photoreceptor surface next to the light-receptive compartment, the rhabdom. To determine the function of myosin-II in these cells, retinal tissue was incubated with 2,3-butanedione 2-monoxime (BDM), an inhibitor of myosin activity. BDM treatment resulted in an increase in surface curvature at precisely those membrane areas that exhibited intense immunoreactivity for MHC. Moreover, the positioning and alignment of the rhabdoms was altered after exposure to BDM. These results suggest that the activity of nonmuscle myosin-II in the visual cells exerts tension on a distinct surface region next to the rhabdom, contributes to the positioning of the rhabdom, and, thus, plays a role in maintaining the cellular architecture within the compound eye.
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Affiliation(s)
- O Baumann
- Institut für Biochemie und Biologie, Tierphysiologie, Universität Potsdam, 14471 Potsdam, Germany.
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45
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Morel V, Poschet R, Traverso V, Deretic D. Towards the proteome of the rhodopsin-bearing post-Golgi compartment of retinal photoreceptor cells. Electrophoresis 2000; 21:3460-9. [PMID: 11079565 DOI: 10.1002/1522-2683(20001001)21:16<3460::aid-elps3460>3.0.co;2-i] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Polarized sorting of rhodopsin in retinal rod photoreceptor cells is mediated by post-Golgi carrier membranes that bud from the trans-Golgi network and fuse with the specialized domain of the plasma membrane in the rod inner segment. The identity of the majority of the resident proteins of this organelle still remains elusive, despite multifaceted approaches to study this compartment. In the present study we have taken a proteomic approach to the analysis of the post-Golgi carriers. First, we modified the previously established fractionation protocols in order to achieve greater purity of the isolated membranes. Specifically, the new fractionation scheme depleted the post-Golgi fraction of cytosolic proteins that were the most abundant contaminants complicating analysis of two-dimensional (2-D) gel profiles in our previous preparations. The isolated membranes were subjected to 2-D gel electrophoresis, immunoblotting and microsequencing. This analysis showed that the improved subcellular fractionation yielded a fraction highly enriched in rhodopsin-bearing post-Golgi carrier membranes. Two-dimensional mapping revealed 29 proteins that are preferentially found in this fraction and therefore represent candidates for post-Golgi membrane-specific proteins. This preparation of rhodopsin-bearing post-Golgi carriers is a first step towards the proteomics of this important organelle.
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Affiliation(s)
- V Morel
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor 48105, USA
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46
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Abstract
We have previously shown in intact isolated eye rudiments from Xenopus laevis that lactose, but not mannose, permits the formation of organized photoreceptor outer segments in the absence of the retinal pigment epithelium (RPE). The purpose of this study was to determine, using electron microscopic analysis, the key ultrastructural differences between healthy retinas, lactose-protected retinas, and retinas that developed aberrantly to reveal which subcellular structures were exclusively present in healthy retinas. Filamentous actin was also localized in retinas to determine its distribution under the various conditions. In healthy retinas, calycal processes extending approximately three-fourths of the length of the outer segment surrounded highly organized photoreceptor outer segments. Adherens junctions were localized between adjacent photoreceptors and Müller cells at the outer limiting membrane. In addition, Müller cells possessed apical processes that extended for a short distance beyond the adherens junctions. These fine cytoarchitectural details were missing in retinas that completed differentiation in the absence of the RPE; both calycal and apical processes were no longer present and adherens junctions were sparsely intermittent. Müller cells appeared atrophic. Similarly, mannose promoted none of the fine cytoarchitectural details of the retina. Lactose, however, supported the formation of the proper subcellular cytoarchitecture of both photoreceptor and Müller cells. These results suggest that these subcellular structures may be fundamental for the proper assembly and stability of organized outer segments and are necessary to allow for normal cytogenesis of the outer retina.
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Affiliation(s)
- M M Jablonski
- Retinal Degeneration Research Center, Department of Ophthalmology, The University of Tennessee, Memphis 38163, USA.
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47
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Sung CH, Tai AW. Rhodopsin trafficking and its role in retinal dystrophies. INTERNATIONAL REVIEW OF CYTOLOGY 1999; 195:215-67. [PMID: 10603577 DOI: 10.1016/s0074-7696(08)62706-0] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
We review the sorting/targeting steps involved in the delivery of rhodopsin to the outer segment compartment of highly polarized photoreceptor cells. The transport of rhodopsin includes (1) the sorting/budding of rhodopsin-containing vesicles at the trans-Golgi network, (2) the directional translocation of rhodopsin-bearing vesicles through the inner segment, and (3) the delivery of rhodopsin across the connecting cilium to the outer segment. Several independent lines of evidence suggest that the carboxyl-terminal, cytoplasmic tail of rhodopsin is involved in the post-Golgi trafficking of rhodopsin. Inappropriate subcellular targeting of naturally occurring rhodopsin mutants in vivo leads to photoreceptor cell death. Thus, the genes encoding mutations in the cellular components involved in photoreceptor protein transport are likely candidate genes for retinal dystrophies.
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Affiliation(s)
- C H Sung
- Department of Cell Biology and Anatomy, Margaret M. Dyson Vision Research Institute, Weill Medical College of Cornell University, New York, New York 10021, USA.
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48
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Paffenholz R, Kuhn C, Grund C, Stehr S, Franke WW. The arm-repeat protein NPRAP (neurojungin) is a constituent of the plaques of the outer limiting zone in the retina, defining a novel type of adhering junction. Exp Cell Res 1999; 250:452-64. [PMID: 10413599 DOI: 10.1006/excr.1999.4534] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the retina, special plaque-bearing adhering junctions are aligned to form a planar system (the "outer limiting zone," OLZ) of heterotypic connections between the photoreceptor cells and the surrounding glial cells ("Müller cells"), together with homotypic junctions. In the plaques of these junctions, which contain N-cadherin-and possibly also related cadherins-we have identified, by immunolocalization techniques, a recently discovered neural tissue-specific protein, neurojungin, a member of the plakoglobin/armadillo protein family. In these plaques we have also detected other adherens plaque proteins, such as alpha- and beta-catenin, protein p120, and vinculin, as well as proteins known as constituents of tight junction plaques, such as symplekin and protein ZO-1, and the desmosomal plaque protein plakophilin 2. This unusual combination of proteins and the demonstrated absence of plakoglobin define the OLZ junctions as a new and distinct category of adhering junction, which probably has special architectural functions.
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Affiliation(s)
- R Paffenholz
- Division of Cell Biology, German Cancer Research Center, Heidelberg, Germany
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49
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Stöffler HE, Honnert U, Bauer CA, Höfer D, Schwarz H, Müller RT, Drenckhahn D, Bähler M. Targeting of the myosin-I myr 3 to intercellular adherens type junctions induced by dominant active Cdc42 in HeLa cells. J Cell Sci 1998; 111 ( Pt 18):2779-88. [PMID: 9718370 DOI: 10.1242/jcs.111.18.2779] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Myr 3, a member of the myosin-I family from rat, is shown in this study to be localized at adherens-type intercellular junctions in epithelial and nonepithelial tissues. Formation of intercellular junctions and the accompanying recruitment of myr 3 to these junctions involves signaling by the Rho subfamily of small GTP-binding proteins. This conclusion is based on studies with HtTA-1 HeLa cells that were induced by overexpression of constitutively active Cdc42Hs to form typical adherens-type intercellular junctions enriched in cadherins (N-cadherin), beta-catenin, filamentous actin and myr 3. Recruitement of myr 3 to Cdc42-induced adherens junctions in HeLa cells was dependent on a short region of the tail domain and a functional myosin motor domain, but was independent of its myosin-I tail homology and SH3 regions. Overexpression of constitutively active Rac1 induced a distinct type of adherens junction in HeLa cells that was characterized by elaborate intercellular interdigitations enriched in N-cadherin, beta-catenin and F-actin. Myr 3 was often present, but not specifically enriched in the intercellular junctions induced by constitutively active Rac1.
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Affiliation(s)
- H E Stöffler
- Adolf-Butenandt-Institute, Cell Biology, Ludwig-Maximilians-University, D-80336 Munich, Germany
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50
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Liu X, Wu TH, Stowe S, Matsushita A, Arikawa K, Naash MI, Williams DS. Defective phototransductive disk membrane morphogenesis in transgenic mice expressing opsin with a mutated N-terminal domain. J Cell Sci 1997; 110 ( Pt 20):2589-97. [PMID: 9372448 DOI: 10.1242/jcs.110.20.2589] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Retinitis pigmentosa is a heterogeneous group of inherited retinal disorders in which the photoreceptor cells degenerate. A line of transgenic mice expresses a mutant opsin gene that encodes three missense mutations near the amino terminus, including P23H, which is the basis for a common form of dominant retinitis pigmentosa. By studying the photoreceptor cells of these mice and their normal littermates, we found that: (1) opsin was routed correctly, (2) the concentration of opsin in the disk membranes appeared normal by freeze fracture analysis, (3) the amount of disk membrane shedding was normal, but (4) the basal disks of the outer segments were disorganized, indicating defective disk membrane morphogenesis. Defective disk membrane morphogenesis appears to result in the formation of fewer mature disks, thus accounting for observed gradual shortening of the photoreceptor outer segments with age. We suggest that abnormal disk membrane morphogenesis is the primary cellular defect that leads to blindness, and that it arises from the inability of nascent disk membranes, containing normal and mutant opsin, to interact normally with each other.
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Affiliation(s)
- X Liu
- Department of Pharmacology, UCSD School of Medicine, La Jolla 92093-0983, USA
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