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Bonilha VL. Retinal pigment epithelium (RPE) cytoskeleton in vivo and in vitro. Exp Eye Res 2013; 126:38-45. [PMID: 24090540 DOI: 10.1016/j.exer.2013.09.015] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 09/18/2013] [Accepted: 09/19/2013] [Indexed: 12/31/2022]
Abstract
The retinal pigment epithelium (RPE) constitutes a monolayer of cuboidal cells that interact apically with the interphotoreceptor matrix (IPM) and outer segments of the photoreceptor cells and basally with the subjacent Bruch's membrane. This highly polarized structure is maintained by the cytoskeleton of individual cells and their interactions at the basolateral junctional complexes that stabilize this epithelial structure. This RPE complex network of filaments, tubules and associated proteins is modeled by the cellular environment, the RPE intercellular interactions, and by its interactions with the extracellular matrix. This is a review of the key features of the RPE cytoskeleton in vivo and in vitro.
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Affiliation(s)
- Vera L Bonilha
- Department of Ophthalmic Research, The Cole Eye Institute, Cleveland Clinic Lerner College of Medicine, 9500 Euclid Avenue i31, Cleveland, OH 44195, USA.
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Thumann G, Hueber A, Dinslage S, Schaefer F, Yasukawa T, Kirchhof B, Yafai Y, Eichler W, Bringmann A, Wiedemann P. Characteristics of iris and retinal pigment epithelial cells cultured on collagen type I membranes. Curr Eye Res 2006; 31:241-9. [PMID: 16531281 DOI: 10.1080/02713680600556966] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
PURPOSE Transplantation of pigment epithelial cells is a promising treatment modality to repair retinal damage in age-related macular degeneration. For this purpose, it is necessary to establish cell culture techniques that allow acquisition of proper functional and morphological characteristics by the cells to be transplanted. METHODS Primary retinal pigment epithelial (RPE) and iris pigment epithelial (IPE) cells grown to confluence on collagen membranes were examined for morphology, adhesion, proliferation, apoptosis, as well as viability after ex vivo transplantation. RESULTS Pigment epithelial cells adhere, proliferate, form monolayers, acquire differentiated properties, and remain viable during transplantation to the subretinal space. CONCLUSIONS Pigment epithelial cells cultured on collagen membranes acquire differentiated characteristics and are amenable to be transplanted as cell monolayers.
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Affiliation(s)
- Gabriele Thumann
- Department of Ophthalmology and IZKF BIOMAT., RHWTH Aachen University, Germany.
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Gordon SR. Microfilament disruption in a noncycling organized tissue, the corneal endothelium, initiates mitosis. Exp Cell Res 2002; 272:127-34. [PMID: 11777337 DOI: 10.1006/excr.2001.5407] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The adult corneal endothelium represents a noncycling cell population that resides as a monolayer on its basement membrane, Descemet's membrane. Evidence is presented for the first time, showing that mitotic regulation in this organized tissue, residing on its natural basement membrane, is coupled to microfilament integrity. When mitotically quiescent rat corneal endothelia are organ cultured in medium containing serum and cytochalasin B, low levels of mitosis are initiated. Supplementing the culture medium with either insulin or IGF-2 augments this response and results in increased cell density within the tissue monolayer. Fluorescence microscopy of actin using TRITC-conjugated phalloidin revealed that cellular circumferential microfilament bundles appear unaffected by cytochalasin B treatment, whereas the cytoplasmic microfilaments appear to be completely disrupted. These results suggest the possibility that the actin cytoskeleton is involved with the regulation of cell growth in the corneal endothelium.
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Affiliation(s)
- Sheldon R Gordon
- Department of Biological Sciences, Oakland University, Rochester, Michigan 48309-4476, USA.
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Korte GE, Perlman JI, Pollack A. Regeneration of mammalian retinal pigment epithelium. INTERNATIONAL REVIEW OF CYTOLOGY 1994; 152:223-63. [PMID: 8206705 DOI: 10.1016/s0074-7696(08)62558-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- G E Korte
- Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, New York 10467
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Hunt RC. Intermediate filaments and other cytoskeletal structures in retinal pigment epithelial cells. Prog Retin Eye Res 1994. [DOI: 10.1016/1350-9462(94)90007-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Höfer D, Drenckhahn D. Molecular heterogeneity of the actin filament cytoskeleton associated with microvilli of photoreceptors, Müller's glial cells and pigment epithelial cells of the retina. HISTOCHEMISTRY 1993; 99:29-35. [PMID: 8468191 DOI: 10.1007/bf00268017] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The present study addressed the question as to whether the four different actin-associated proteins that are associated with the actin core bundle in intestinal microvilli (i.e. villin, fimbrin, myosin I and ezrin) are essential components of all microvilli of the body. The retina provides an excellent example of a tissue supplied with three different sets of microvilli, namely those of Müller's glial cells (Müller baskets), photoreceptors (calycal processes), and pigment epithelial cells. The main outcome of this study is that none of these microvilli contain all four actin-associated proteins present in intestinal microvilli. Müller cell microvilli contain villin, ezrin and myosin I (95 kDa isoform) but not fimbrin. Calycal processes of photoreceptors contain fimbrin but not villin, myosin I and ezrin. Finally, microvilli of pigment epithelial cells are positive for ezrin but not for villin, fimbrin and myosin I. Because of limited cross-reactivities of the antibodies to myosin I and ezrin, the myosin I data refer to the chicken retina whereas the findings with anti-ezrin were obtained with the rat retina. A further outcome of this study is that the actin filament core bundles in microvilli of chicken pigment epithelial cells are presumed to contain a crosslinking protein, which is not immunologically related to either villin, fimbrin or myosin I of the intestinal brush border.
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Affiliation(s)
- D Höfer
- Department of Anatomy, Julius-Maximilians-University, Würzburg, Germany
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Schafer DA, Mooseker MS, Cooper JA. Localization of capping protein in chicken epithelial cells by immunofluorescence and biochemical fractionation. J Biophys Biochem Cytol 1992; 118:335-46. [PMID: 1629237 PMCID: PMC2290044 DOI: 10.1083/jcb.118.2.335] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
We have localized capping protein in epithelial cells of several chicken tissues using affinity-purified polyclonal antibodies and immunofluorescence. Capping protein has a distribution in each tissue coincident with proteins of the cell-cell junctional complex, which includes the zonula adherens, zonula occludens, and desmosome. "En face" views of the epithelial cells showed capping protein distributed in a polygonal pattern coincident with cell boundaries in intestinal epithelium, sensory epithelium of the cochlea, and the pigmented epithelium of the retina and at regions of cell-cell contact between chick embryo kidney cells in culture. "Edge-on" views obtained by confocal microscopy of intact single intestinal epithelial cells and of retinal pigmented epithelium showed that capping protein is located in the apical region of the epithelial cells coincident with the junctional complexes. These images do not resolve the individual types of junctions of the junctional complex. Immunolabeling of microvilli or stereocilia was faint or not detectable. Capping protein was also detected in the cytoplasm of intact intestinal epithelial cells and in nuclei of cells in the pigmented retina and in the kidney cell cultures, but not in nuclei of cells of the intestinal epithelium or sensory epithelium. Biochemical fractionation of isolated intestinal epithelial cells shows capping protein in the brush border fraction, which contains the junctional complexes, and in the soluble fraction. These results are consistent with the results of the immunolabeling experiments. Highly purified microvilli of the brush borders also contained capping protein; this result was unexpected based on the low intensity of immunofluorescence staining of microvilli and stereocilia. The microvilli were not contaminated with junctional complexes, as defined by the absence of several markers for cell junctions. The cause and significance of this discrepancy is not certain at this time. Since capping protein binds the barbed end of actin filaments in vitro, we hypothesize that capping protein is bound to the barbed ends of actin filaments associated with one or more of the junctions of the junctional complex.
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Affiliation(s)
- D A Schafer
- Department of Cell Biology, Washington University School of Medicine, St. Louis, Missouri 63110
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Sandig M, Kalnins VI. Morphological changes in the zonula adhaerens during embryonic development of chick retinal pigment epithelial cells. Cell Tissue Res 1990; 259:455-61. [PMID: 2317840 DOI: 10.1007/bf01740771] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Retinal pigment epithelial cells from chicks at various stages of development were examined by transmission electron microscopy to determine how the adult form of the zonula adhaerens, composed of subunits termed zonula adhaerens complexes, is acquired. During early stages of development, between embryonic day 4 and embryonic day 7, the intermembrane discs of zonula adhaerens complexes appear to be formed from material already present between the junctional membranes of the zonulae adhaerentes. In contrast, the cytoplasmic plaque material of the zonulae adhaerentes is difficult to detect before hatching; it is seen as a dense band along the junctional membranes at hatching and as individual subunits in register with the intermembrane discs in adult retinal pigment epithelial cells. After embryonic day 16, when the zonulae adhaerentes increase dramatically in size, single zonula adhaerens complexes are also present basal to the zonulae adhaerentes along the lateral cell membrane. This suggests that, during later stages of development, the junctions grow in size and/or turn over by the addition of pre-assembled zonula adhaerens complexes.
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Affiliation(s)
- M Sandig
- Department of Anatomy, University of Toronto, Ontario, Canada
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Sandig M, Kalnins VI. Reorganization of circumferential microfilament bundles in retinal epithelial cells during mitosis. CELL MOTILITY AND THE CYTOSKELETON 1990; 17:133-41. [PMID: 2257631 DOI: 10.1002/cm.970170208] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
To examine the behaviour of the apical circumferential microfilament bundles (CMBs) associated with the zonula adhaerens (ZA)-junctions during mitosis, retinal pigment epithelial cells were labelled for F-actin, and retinas were serially sectioned for TEM. The results show that the ZA-CMB-complex persists throughout all stages of mitosis. At metaphase, the cells round up, but stay joined apically to adjacent cells by ZA-junctions. At telophase, the cleavage furrow forms asymmetrically from the basal end progressively toward the apical end, where the daughter cells remain connected by an intercellular bridge (IB). As the cleavage furrow with the contractile ring (CR) approaches the CMB, the two microfilament (MF) systems are oriented perpendicularly to each other. At the level of the CMB, the MFs of the CR connect the opposite sides of the CMB and bisect it into two CMBs, one for each of the two daughter cells. Subsequently, the CR in the IB splits into two, one on either side of the midbody. The two daughter cells, having acquired a complete CMB of their own, do not become direct neighbours, since adjacent cells, which remain joined to the apical ZA-junction of the dividing cell, are observed in the cleavage furrow, where they meet and form a ZA-junction between themselves, just below the IB. Separation of the daughter cells without losing contact with neighbouring cells at the level of the apical ZA-junction thus maintains the integrity of the epithelial sheet during mitosis.
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Affiliation(s)
- M Sandig
- Department of Anatomy, University of Toronto, Ontario, Canada
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Sandig M, Hergott GJ, Kalnins VI. Effects of trypsin and low Ca2+ on zonulae adhaerentes between chick retinal pigment epithelial cells in organ culture. CELL MOTILITY AND THE CYTOSKELETON 1990; 17:46-58. [PMID: 2225088 DOI: 10.1002/cm.970170107] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The junctional complexes in chick retinal pigment epithelial (RPE) cells in situ contain unusually large zonulae adhaerentes (ZAs) composed of subunits termed zonula adhaerens complexes (ZACs). To determine whether the properties of the ZAs differ between RPE cells which contain ZACs, and MDCK cells which lack ZACs, we investigated the effects of treatment with trypsin and/or low Ca2+ by transmission electron microscopy and staining for F-actin. Treatment of RPE cells for 1 h with trypsin alone has no apparent effect on the morphology of the ZA in either MDCK or RPE cells. In contrast to the ZAs in MDCK cells, which split after 3 min in low Ca2+, the ZAs in chick RPE cells stay intact even after 2 h, although the intermembrane discs, i.e., the extracellular components of the ZACs, are no longer visible. After 30 min of treatment with trypsin and low Ca2+, the ZAs split in both cell types. The CMBs start to contract, translocate toward the cell interior, and eventually disappear. This process continues even when the RPE cells are returned to normal medium. New ZAs, composed of ZACs, form between RPE cells 3 h after return to normal medium. These findings suggest that the ZACs in the ZAs of RPE cells are not directly responsible for the increase in resistance to low Ca2+. They also show that the ZA-junctions in RPE cells are not only structurally different from those previously examined, but also behave differently in response to experimental manipulation.
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Affiliation(s)
- M Sandig
- Department of Anatomy, University of Toronto, Ontario, Canada
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Hergott GJ, Sandig M, Kalnins VI. Cytoskeletal organization of migrating retinal pigment epithelial cells during wound healing in organ culture. CELL MOTILITY AND THE CYTOSKELETON 1989; 13:83-93. [PMID: 2766363 DOI: 10.1002/cm.970130203] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Retinal pigment epithelial (RPE) cells maintained in organ culture on Bruch's membrane and the associated choroid spread and migrate into a linear wound along the exposed basal lamina. Changes in cell shape, in the organization of microfilaments, and in cell-cell and cell-substratum interactions during this time were examined by epifluorescence and transmission electron microscopy. In contrast to cuboidal stationary cells distant from the wound edge, which display well-developed apical circumferential microfilament bundles (CMBs) associated with zonulae adhaerentes junctions, the migrating RPE cells near the wound edge instead are flat, and, in addition to microfilament bundles near junctions between adjacent cells, display prominent stress fibers. Furthermore, monoclonal antibodies to vinculin labeled regions at the terminal ends of these stress fibers indicating that the RPE cells form focal contacts with the basal lamina at these sites. Electron microscopy of these regions of cell-substratum interaction confirmed the presence of microfilament bundles that terminate on the cell membrane. Folds present in the basal lamina near these sites suggest that tension is being generated by the microfilaments in the stress fibers as the migrating cells pull on the underlying basal lamina through these adhesion points.
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Affiliation(s)
- G J Hergott
- Department of Anatomy, University of Toronto, Ontario, Canada
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Owaribe K, Kartenbeck J, Rungger-Brändle E, Franke WW. Cytoskeletons of retinal pigment epithelial cells: interspecies differences of expression patterns indicate independence of cell function from the specific complement of cytoskeletal proteins. Cell Tissue Res 1988; 254:301-15. [PMID: 3058315 DOI: 10.1007/bf00225803] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In vertebrate tissue development a given cell differentiation pathway is usually associated with a pattern of expression of a specific set of cytoskeletal proteins, including different intermediate filament (IF) and junctional proteins, which is identical in diverse species. The retinal pigment epithelium (RPE) is a layer of polar cells that have very similar morphological features and practically identical functions in different vertebrate species. However, in biochemical and immunolocalization studies of the cytoskeletal proteins of these cells we have noted remarkable interspecies differences. While chicken RPE cells contain only IFs of the vimentin type and do not possess desmosomes and desmosomal proteins RPE cells of diverse amphibian (Rana ridibunda, Xenopus laevis) and mammalian (rat, guinea pig, rabbit, cow, human) species express cytokeratins 8 and 18 either as their sole IF proteins, or together with vimentin IFs as in guinea pig and a certain subpopulation of bovine RPE cells. Plakoglobin, a plaque protein common to desmosomes and the zonula adhaerens exists in RPE cells of all species, whereas desmoplakin and desmoglein have been identified only in RPE desmosomes of frogs and cows, including bovine RPE cell cultures in which cytokeratins have disappeared and vimentin IFs are the only IFs present. These challenging findings show that neither cytokeratin IFs nor desmosomes are necessary for the establishment and function of a polar epithelial cell layer and that the same basic cellular architecture can be achieved by different programs of expression of cytoskeletal proteins. The differences in the composition of the RPE cytoskeleton further indicate that, at least in this tissue, a specific program of expression of IF and desmosomal proteins is not related to the functions of the RPE cell, which are very similar in the various species.
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Affiliation(s)
- K Owaribe
- Division of Membrane Biology and Biochemistry, German Cancer Research Center, Heidelberg
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Temporo-spatial distribution of matrix and microfilament components during odontoblast and ameloblast differentiation. ACTA ACUST UNITED AC 1988; 197:212-220. [DOI: 10.1007/bf02439428] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/1987] [Accepted: 12/03/1988] [Indexed: 11/27/2022]
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Sandig M, Kalnins VI. Subunits in zonulae adhaerentes and striations in the associated circumferential microfilament bundles in chicken retinal pigment epithelial cells in situ. Exp Cell Res 1988; 175:1-14. [PMID: 3345796 DOI: 10.1016/0014-4827(88)90250-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
This study shows that the zonula adhaerens in chicken retinal pigment epithelial (RPE) cells in situ consists of independent subunits which are composed of extracellular intermembrane discs sandwiched between cytoplasmic plaques. These zonula adhaerens complexes (ZACs) are hexagonally arranged within the junction. Previous immunocytochemical studies suggest that the zonula adhaerens region, composed of ZACs, contains the actin associated proteins vinculin and alpha-actinin. The intermembrane discs of ZACs likely mediate cell-to-cell adhesion whereas the cytoplasmic plaques are probably involved in binding the microfilaments of the relatively large circumferential microfilament bundles (CMBs), associated with the zonula adhaerens, to the cell membrane. The CMBs of chicken RPE cells in situ show striations similar to those found in stress fibers of other cell types and in CMBs of cultured epithelial cells. The observation that in the striated regions of CMBs the adjacent junctional membranes tend to follow an undulating path suggests that the CMBs are attached intermittently to the cell membrane and are contractile. The structural similarities between CMBs and stress fibers and the fact that they share similar actin associated proteins support the view that CMBs and stress fibers are related structures.
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Affiliation(s)
- M Sandig
- Department of Anatomy, University of Toronto, Ontario, Canada
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