1551
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François A, Grauso M, Demondion E, Bozzolan F, Debernard S, Lucas P. Bestrophin-encoded Ca²⁺-activated Cl⁻ channels underlie a current with properties similar to the native current in the moth Spodoptera littoralis olfactory receptor neurons. PLoS One 2012; 7:e52691. [PMID: 23300744 PMCID: PMC3530479 DOI: 10.1371/journal.pone.0052691] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2012] [Accepted: 11/20/2012] [Indexed: 11/19/2022] Open
Abstract
Responses of insect olfactory receptor neurons (ORNs) involve an entry of Ca2+ through olfactory heterodimeric receptor complexes. In moths, the termination of ORN responses was found to strongly depend on the external Ca2+ concentration through the activation of unknown Ca2+-dependent Cl− channels. We thus investigated the molecular identity of these Cl− channels. There is compelling evidence that bestrophins form Cl− channels when expressed in heterologous systems. Here we provide evidence that antennae of the moth Spodoptera littoralis express three transcripts encoding proteins with hallmarks of bestrophins. One of these transcripts, SlitBest1b, is expressed in ORNs. The heterologous expression of SlitBest1b protein in CHO-K1 cells yielded a Ca2+-activated Cl− current that shares electrophysiological properties with the native Ca2+-activated Cl− current of ORNs. Both currents are anionic, present similar dependence on the intracellular Ca2+ concentration, partly inactivate over time, have the same anion permeability sequence, the same sequence of inhibitory efficiency of blockers, the same almost linear I–V relationships and finally both currents do not depend on the cell volume. Therefore, our data suggest that SlitBest1b is a good candidate for being a molecular component of the olfactory Ca2+-activated Cl− channel and is likely to constitute part of the insect olfactory transduction pathway. A different function (e.g. regulation of other proteins, maintenance of the anionic homeostasis in the sensillar lymph) and a different role (e.g. involvement in the olfactory system development) cannot be excluded however.
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Affiliation(s)
- Adrien François
- Institut National de la Recherche Agronomique, UMR 1272 Physiologie de l’Insecte : Signalisation et Communication, Versailles, France
- Université Pierre et Marie Curie, UMR 1272 Physiologie de l’Insecte: Signalisation et Communication, Paris, France
| | - Marta Grauso
- Institut National de la Recherche Agronomique, UMR 1272 Physiologie de l’Insecte : Signalisation et Communication, Versailles, France
| | - Elodie Demondion
- Institut National de la Recherche Agronomique, UMR 1272 Physiologie de l’Insecte : Signalisation et Communication, Versailles, France
| | - Françoise Bozzolan
- Université Pierre et Marie Curie, UMR 1272 Physiologie de l’Insecte: Signalisation et Communication, Paris, France
| | - Stéphane Debernard
- Université Pierre et Marie Curie, UMR 1272 Physiologie de l’Insecte: Signalisation et Communication, Paris, France
| | - Philippe Lucas
- Institut National de la Recherche Agronomique, UMR 1272 Physiologie de l’Insecte : Signalisation et Communication, Versailles, France
- * E-mail:
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1552
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Robert V, Triffaux E, Savignac M, Pelletier L. Singularities of calcium signaling in effector T-lymphocytes. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:1595-602. [PMID: 23266355 DOI: 10.1016/j.bbamcr.2012.12.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Revised: 11/30/2012] [Accepted: 12/01/2012] [Indexed: 12/30/2022]
Abstract
CD4(+) helper T (Th) lymphocytes orchestrate the immune response and include several types of effectors such as Th1, Th17 and Th2 cells. They fight against intracellular, extracellular pathogens and parasites respectively. They may also cause distinct immunopathological disorders. Th1 and Th17 are implicated in the development of autoimmune diseases while Th2 cells can initiate allergic diseases. These subsets differ by their TCR-associated signaling. In addition, the regulation of intracellular calcium concentration is not the same in Th1, Th2 and 17 cells. Our group showed that Th2 cells selectively overexpressed voltage-activated calcium (Cav1)-related channels. An increasing number of groups report the presence of Cav1-related products in T-lymphocyte subsets. This is a matter of debate since these calcium channels are classically defined as activated by high cell membrane depolarization in excitable cells. However, the use of mice with ablation of some Cav1 subunits shows undoubtedly an immune phenotype raising the question of how Cav1 channels are regulated in lymphocytes. We showed that knocking down Cav1.2 and/or Cav1.3 subunits impairs the functions of Th2 lymphocytes and is beneficial in experimental models of asthma, while it has no effect on Th1 cell functions. Beyond the role of Cav1 channels in T-lymphocytes, the identification of key components selectively implicated in one or the other T cell subset paves the way for the design of new selective therapeutic targets in the treatment of immune disorders while preserving the other T-cell subsets. This article is part of a Special Issue entitled: 12th European Symposium on Calcium.
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1553
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Zhang W, Zhang X, Wang H, Sharma AK, Edwards AO, Hughes BA. Characterization of the R162W Kir7.1 mutation associated with snowflake vitreoretinopathy. Am J Physiol Cell Physiol 2012; 304:C440-9. [PMID: 23255580 DOI: 10.1152/ajpcell.00363.2012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
KCNJ13 encodes Kir7.1, an inwardly rectifying K(+) channel that is expressed in multiple ion-transporting epithelia. A mutation in KCNJ13 resulting in an arginine-to-tryptophan change at residue 162 (R162W) of Kir7.1 was associated with snowflake vitreoretinal degeneration, an inherited autosomal-dominant disease characterized by vitreous degeneration and mild retinal degeneration. We used the Xenopus laevis oocyte expression system to assess the functional properties of the R162W (mutant) Kir7.1 channel and determine how wild-type (WT) Kir7.1 is affected by the presence of the mutant subunit. Recordings obtained via the two-electrode voltage-clamp technique revealed that injection of oocytes with mutant Kir7.1 cRNA resulted in currents and cation selectivity that were indistinguishable from those in water-injected oocytes, suggesting that the mutant protein does not form functional channels in the plasma membrane. Coinjection of oocytes with equal amounts of mutant and WT Kir7.1 cRNAs resulted in inward K(+) and Rb(+) currents with amplitudes that were ∼17% of those in oocytes injected with WT Kir7.1 cRNA alone, demonstrating a dominant-negative effect of the mutant subunit. Similar to oocytes injected with WT Kir7.1 cRNA alone, coinjected oocytes exhibited inwardly rectifying Rb(+) currents that were more than seven times larger than K(+) currents, indicating that mutant subunits did not alter Kir7.1 channel selectivity. Immunostaining of Xenopus oocytes or Madin-Darby canine kidney cells expressing mutant or WT Kir7.1 demonstrated distribution of both proteins primarily in the plasma membrane. Our data suggest that the R162W mutation suppresses Kir7.1 channel activity, possibly by negatively impacting gating by membrane phosphadidylinositol 4,5-bisphosphate.
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Affiliation(s)
- Wei Zhang
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105, USA
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1554
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Gómez NM, Tamm ER, Strauβ O. Role of bestrophin-1 in store-operated calcium entry in retinal pigment epithelium. Pflugers Arch 2012. [PMID: 23207577 DOI: 10.1007/s00424-012-1181-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The retinal pigment epithelium (RPE) expresses bestrophin-1 where mutant bestrophin cause retinal degenerations. Overexpression of bestrophin-1 demonstrated Ca(2+)-dependent Cl(-) channel function, whereas the RPE in bestrophin-1 knockout or mutant bestrophin-1 knock-in mice showed no change in Cl(-) conductance. To account for these apparently mutually exclusive findings, we investigated the function of endogenously expressed bestrophin-1 in a short-time RPE cell culture system by means of immunocytochemistry, Ca(2+) imaging, and siRNA knockdown. Immunocytochemical quantification of bestrophin-1 localization demonstrated 2.5 times higher co-localization with the endoplasmic reticulum (ER) Ca(2+)-sensor protein, Stim-1, than with the membrane protein β-catenin, implicating it in store-operated Ca(2+) entry (SOCE). Ca(2+) release from ER stores under extracellular Ca(2+)-free conditions using thapsigargin (1 μM) to inhibit endoplasmic Ca(2+) ATPase (SERCA) followed by re-adjustment of extracellular Ca(2+) to physiological levels activated SOCE, which was insensitive to the blocker of numerous transient receptor potential channels and voltage-dependent Ca(2+) channels SKF96563 (1 μM). SOCE was augmented at 5 μM and inhibited at 75 μM by 2-aminoethoxydiphenyl borate which indicates the involvement Orai-1 channels. In confirmation, SOCE was decreased by siRNA knockdown of Orai-1 expression. SOCE amplitude was strongly reduced by siRNA knockdown of bestrophin-1 expression, which was due to neither changes in Stim-1/Orai-1 expression nor Stim-1/bestrophin-1 interaction. The amount of Ca(2+) released by SERCA inhibition was reduced after siRNA knockdown of bestrophin-1, but not of Orai-1. In conclusion we found that a proportion of bestrophin-1 is functionally localized to ER Ca(2+) stores where it influences the amount of Ca(2+) and therefore Ca(2+) signals which result from activation of Orai-1 via Stim-1.
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Affiliation(s)
- Néstor Más Gómez
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Franz-Josef-Strauss-Allee 11, 93053, Regensburg, Germany
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1555
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Giansanti V, Villalpando Rodriguez GE, Savoldelli M, Gioia R, Forlino A, Mazzini G, Pennati M, Zaffaroni N, Scovassi AI, Torriglia A. Characterization of stress response in human retinal epithelial cells. J Cell Mol Med 2012. [PMID: 23205553 PMCID: PMC3823140 DOI: 10.1111/j.1582-4934.2012.01652.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The pathogenesis of age-related macular degeneration (AMD) involves demise of the retinal pigment epithelium and death of photoreceptors. In this article, we investigated the response of human adult retinal pigmented epithelial (ARPE-19) cells to 5-(N,N-hexamethylene)amiloride (HMA), an inhibitor of Na+/H+ exchangers. We observed that ARPE-19 cells treated with HMA are unable to activate ‘classical’ apoptosis but they succeed to activate autophagy. In the first 2 hrs of HMA exposure, autophagy is efficient in protecting cells from death. Thereafter, autophagy is impaired, as indicated by p62 accumulation, and this protective mechanism becomes the executioner of cell death. This switch in autophagy property as a function of time for a single stimulus is here shown for the first time. The activation of autophagy was observed, at a lesser extent, with etoposide, suggesting that this event might be a general response of ARPE cells to stress and the most important pathway involved in cell resistance to adverse conditions and toxic stimuli.
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Affiliation(s)
| | - Gloria E Villalpando Rodriguez
- U872 eq. 17, Centre de Recherches des Cordeliers, INSERMParis, France
- Centre de Recherches des Cordeliers, Université Pierre et Marie CurieParis, France
- Centre de Recherches des Cordeliers, Université Paris DescartesParis, France
| | | | - Roberta Gioia
- Dipartimento di Biochimica, Università di PaviaPavia, Italy
| | | | | | - Marzia Pennati
- Department of Experimental Oncology, Fondazione IRCCS Istituto Nazionale dei TumoriMilano, Italy
| | - Nadia Zaffaroni
- Department of Experimental Oncology, Fondazione IRCCS Istituto Nazionale dei TumoriMilano, Italy
| | | | - Alicia Torriglia
- U872 eq. 17, Centre de Recherches des Cordeliers, INSERMParis, France
- Centre de Recherches des Cordeliers, Université Pierre et Marie CurieParis, France
- Centre de Recherches des Cordeliers, Université Paris DescartesParis, France
- *Correspondence to: Alicia TORRIGLIA, U872 eq. 17, Centre de Recherches des Cordeliers, INSERM, Paris, France. Tel: +33 1 44 27 81 73 Fax: +33 1 44 27 81 83 E-mail:
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1556
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Chen YH, Chou HC, Lin ST, Chen YW, Lo YW, Chan HL. Effect of high glucose on secreted proteome in cultured retinal pigmented epithelium cells: Its possible relevance to clinical diabetic retinopathy. J Proteomics 2012; 77:111-28. [DOI: 10.1016/j.jprot.2012.07.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Revised: 07/01/2012] [Accepted: 07/04/2012] [Indexed: 10/28/2022]
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1557
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Barro-Soria R, Stindl J, Müller C, Foeckler R, Todorov V, Castrop H, Strauß O. Angiotensin-2-mediated Ca2+ signaling in the retinal pigment epithelium: role of angiotensin-receptor-associated-protein and TRPV2 channel. PLoS One 2012. [PMID: 23185387 PMCID: PMC3502274 DOI: 10.1371/journal.pone.0049624] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Angiotensin II (AngII) receptor (ATR) is involved in pathologic local events such as neovascularisation and inflammation including in the brain and retina. The retinal pigment epithelium (RPE) expresses ATR in its AT1R form, angiotensin-receptor-associated protein (Atrap), and transient-receptor-potential channel-V2 (TRPV2). AT1R and Atrap co-localize to the basolateral membrane of the RPE, as shown by immunostaining. Stimulation of porcine RPE (pRPE) cells by AngII results in biphasic increases in intracellular free Ca(2+)inhibited by losartan. Xestospongin C (xest C) and U-73122, blockers of IP3R and PLC respectively, reduced AngII-evoked Ca(2+)response. RPE cells from Atrap(-/-) mice showed smaller AngII-evoked Ca(2+)peak (by 22%) and loss of sustained Ca(2+)elevation compared to wild-type. The TRPV channel activator cannabidiol (CBD) at 15 µM stimulates intracellular Ca(2+)-rise suggesting that porcine RPE cells express TRPV2 channels. Further evidence supporting the functional expression of TRPV2 channels comes from experiments in which 100 µM SKF96365 (a TRPV channel inhibitor) reduced the cannabidiol-induced Ca(2+)-rise. Application of SKF96365 or reduction of TRPV2 expression by siRNA reduced the sustained phase of AngII-mediated Ca(2+)transients by 53%. Thus systemic AngII, an effector of the local renin-angiotensin system stimulates biphasic Ca(2+)transients in the RPE by releasing Ca(2+)from cytosolic IP3-dependent stores and activating ATR/Atrap and TRPV2 channels to generate a sustained Ca(2+)elevation.
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Affiliation(s)
- Rene Barro-Soria
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany
| | - Julia Stindl
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany
| | - Claudia Müller
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany
| | - Renate Foeckler
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany
| | - Vladimir Todorov
- Institute of Physiology, University of Regensburg, Regensburg, Germany
- Laboratory for Experimental Nephrology, Dresden University of Technology, Dresden, Germany
| | - Hayo Castrop
- Institute of Physiology, University of Regensburg, Regensburg, Germany
| | - Olaf Strauß
- Experimental Ophthalmology, Eye Hospital, University Medical Center Regensburg, Regensburg, Germany
- * E-mail:
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1558
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Lane BM, Lister JA. Otx but not Mitf transcription factors are required for zebrafish retinal pigment epithelium development. PLoS One 2012; 7:e49357. [PMID: 23139843 PMCID: PMC3489725 DOI: 10.1371/journal.pone.0049357] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Accepted: 10/10/2012] [Indexed: 11/29/2022] Open
Abstract
Otx and Mitf transcription factors have been implicated in the development of the retinal pigmented epithelium (RPE), but the relationship between these factors and their specific roles in the development of the RPE have not been fully defined. The role of the three Otx transcription factors (Otx1a, Otx1b, and Otx2) and two Mitf transcription factors (Mitfa and Mitfb) in the development of the zebrafish RPE was explored in these experiments. The loss of Otx activity through morpholino knockdown produced variable eye defects, ranging from delayed RPE pigmentation to severe coloboma, depending on the combination of Otx factors that were targeted. Expression analysis through in situ hybridization demonstrates that otx transcription factors are necessary for the proper expression of mitfa and mitfb while Mitf transcription factors are not required for the expression of otx genes. Surprisingly, the loss of Mitf activity in mitfa, mitfb, or double mitf mutant zebrafish had no effect on RPE pigmentation or development. Moreover, histological analysis revealed that retinal lamination is unaffected in mitf mutants, as well as in otx morphants, even in regions lacking RPE. Otx and Mitf combined loss of function experiments suggest that mitfa and mitfb may still influence zebrafish RPE development. This is further supported by the ability of mitfa to induce pigmentation in the zebrafish retina when misexpressed. These findings suggest that one or more Otx targets in addition to mitfa and mitfb, possibly another mitf family member, are necessary for development of the RPE in zebrafish.
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Affiliation(s)
- Brandon M. Lane
- Department of Human and Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, Virginia, United States of America
| | - James A. Lister
- Department of Human and Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, Virginia, United States of America
- * E-mail:
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1559
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Różanowska M, Handzel K, Boulton ME, Różanowski B. Cytotoxicity of all-trans-retinal increases upon photodegradation. Photochem Photobiol 2012; 88:1362-72. [PMID: 22515697 PMCID: PMC3644973 DOI: 10.1111/j.1751-1097.2012.01161.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
All-trans-retinal (AtRal) can accumulate in the retina as a result of excessive exposure to light. The purpose of this study was to compare cytotoxicity of AtRal and photodegraded AtRal (dAtRal) on cultured human retinal pigment epithelial cells in dark and upon exposure to visible light. AtRal was degraded by exposure to visible light. Cytotoxicity was monitored by imaging of cell morphology, propidium iodide staining of cells with permeable plasma membrane and measurements of reductive activity of cells. Generation of singlet oxygen photosensitized by AtRal and dAtRal was monitored by time-resolved measurements of characteristic singlet oxygen phosphorescence. Photodegradation of AtRal resulted in a decrease in absorption of visible light and accumulation of the degradation products with absorption maximum at ∼330 nm. Toxicity of dAtRal was concentration-dependent and was greater during irradiation with visible light than in dark. DAtRal was more cytotoxic than AtRal both in dark and during exposure to visible light. Photochemical properties of dAtRal indicate that it may be responsible for the maximum in the action spectra of retinal photodamage recorded in animals. In conclusion, photodegradation products of AtRal may impose a significant threat to the retina and therefore their roles in retinal pathology need to be explored.
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Affiliation(s)
- Małgorzata Różanowska
- School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, Wales, UK.
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1560
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Różanowska M, Bakker L, Boulton ME, Różanowski B. Concentration dependence of vitamin C in combinations with vitamin E and zeaxanthin on light-induced toxicity to retinal pigment epithelial cells. Photochem Photobiol 2012; 88:1408-17. [PMID: 22924673 PMCID: PMC3484246 DOI: 10.1111/j.1751-1097.2012.01228.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Accepted: 08/20/2012] [Indexed: 01/08/2023]
Abstract
The purpose of this study was to determine the effects of increasing concentration of ascorbate alone and in combinations with α-tocopherol and zeaxanthin on phototoxicity to the retinal pigment epithelium. ARPE-19 cells were exposed to rose bengal and visible light in the presence and absence of antioxidants. Toxicity was quantified by an assay of cell-reductive activity. A 20 min exposure to visible light and photosensitizer decreased cell viability to ca 42%. Lipophilic antioxidants increased viabilities to ca 70%, 61% and 75% for α-tocopherol, zeaxanthin and their combination, respectively. Cell viabilities were ca 70%, 56% and 5% after exposures in the presence of 0.35, 0.7 and 1.4 mm ascorbate, respectively. A 45 min exposure increased cell death to ca 74% and >95% in the absence and presence of ascorbate, respectively. In the presence of ascorbate, zeaxanthin did not significantly affect phototoxicity. α-Tocopherol and its combination with zeaxanthin enhanced protective effects of ascorbate, but did not prevent from ascorbate-mediated deleterious effects. In conclusion, there is a narrow range of concentrations and exposure times where ascorbate exerts photoprotective effects, exceeding which leads to ascorbate-mediated increase in photocytotoxicity. Vitamin E and its combination with zeaxanthin can enhance protective effects of ascorbate, but do not ameliorate its deleterious effects.
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1561
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Szober CM, Hauck SM, Euler KN, Fröhlich KJH, Alge-Priglinger C, Ueffing M, Deeg CA. Profound re-organization of cell surface proteome in equine retinal pigment epithelial cells in response to in vitro culturing. Int J Mol Sci 2012. [PMID: 23203049 PMCID: PMC3509565 DOI: 10.3390/ijms131114053] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The purpose of this study was to characterize the cell surface proteome of native compared to cultured equine retinal pigment epithelium (RPE) cells. The RPE plays an essential role in visual function and represents the outer blood-retinal barrier. We are investigating immunopathomechanisms of equine recurrent uveitis, an autoimmune inflammatory disease in horses leading to breakdown of the outer blood-retinal barrier and influx of autoreactive T-cells into affected horses’ vitrei. Cell surface proteins of native and cultured RPE cells from eye-healthy horses were captured by biotinylation, analyzed by high resolution mass spectrometry coupled to liquid chromatography (LC MS/MS), and the most interesting candidates were validated by PCR, immunoblotting and immunocytochemistry. A total of 112 proteins were identified, of which 84% were cell surface membrane proteins. Twenty-three of these proteins were concurrently expressed by both cell states, 28 proteins exclusively by native RPE cells. Among the latter were two RPE markers with highly specialized RPE functions: cellular retinaldehyde-binding protein (CRALBP) and retinal pigment epithelium-specific protein 65kDa (RPE65). Furthermore, 61 proteins were only expressed by cultured RPE cells and absent in native cells. As we believe that initiating events, leading to the breakdown of the outer blood-retinal barrier, take place at the cell surface of RPE cells as a particularly exposed barrier structure, this differential characterization of cell surface proteomes of native and cultured equine RPE cells is a prerequisite for future studies.
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Affiliation(s)
- Christoph M. Szober
- Institute of Animal Physiology, Department of Veterinary Sciences, Ludwig-Maximilians-University Munich, D-80539 Munich, Germany; E-Mails: (C.M.S.); (K.N.E.); (K.J.H.F.)
| | - Stefanie M. Hauck
- Research Unit Protein Science, Helmholtz Center Munich, German Research Center for Environmental Health, D-85764 Neuherberg, Germany; E-Mails: (S.M.H.); (M.U.)
| | - Kerstin N. Euler
- Institute of Animal Physiology, Department of Veterinary Sciences, Ludwig-Maximilians-University Munich, D-80539 Munich, Germany; E-Mails: (C.M.S.); (K.N.E.); (K.J.H.F.)
| | - Kristina J. H. Fröhlich
- Institute of Animal Physiology, Department of Veterinary Sciences, Ludwig-Maximilians-University Munich, D-80539 Munich, Germany; E-Mails: (C.M.S.); (K.N.E.); (K.J.H.F.)
| | - Claudia Alge-Priglinger
- Department of Ophthalmology, Ludwig-Maximilians-University, Mathildenstrasse 8, D-80336 Munich, Germany; E-Mail:
| | - Marius Ueffing
- Research Unit Protein Science, Helmholtz Center Munich, German Research Center for Environmental Health, D-85764 Neuherberg, Germany; E-Mails: (S.M.H.); (M.U.)
- Centre of Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Röntgenweg 11, D-72076 Tübingen, Germany
| | - Cornelia A. Deeg
- Institute of Animal Physiology, Department of Veterinary Sciences, Ludwig-Maximilians-University Munich, D-80539 Munich, Germany; E-Mails: (C.M.S.); (K.N.E.); (K.J.H.F.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +49-89-21801630; Fax: +49-89-21802554
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1562
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Exclusion of aldose reductase as a mediator of ERG deficits in a mouse model of diabetic eye disease. Vis Neurosci 2012; 29:267-74. [PMID: 23101909 DOI: 10.1017/s0952523812000326] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Streptozotocin (STZ)-induced diabetes is associated with reductions in the electrical response of the outer retina and retinal pigment epithelium (RPE) to light. Aldose reductase (AR) is the first enzyme required in the polyol-mediated metabolism of glucose, and AR inhibitors have been shown to improve diabetes-induced electroretinogram (ERG) defects. Here, we used control and AR -/- mice to determine if genetic inactivation of this enzyme likewise inhibits retinal electrophysiological defects observed in a mouse model of type 1 diabetes. STZ was used to induce hyperglycemia and type 1 diabetes. Diabetic and age-matched nondiabetic controls of each genotype were maintained for 22 weeks, after which ERGs were used to measure the light-evoked components of the RPE (dc-ERG) and the neural retina (a-wave, b-wave). In comparison to their nondiabetic controls, wildtype (WT) and AR -/- diabetic mice displayed significant decreases in the c-wave, fast oscillation, and off response components of the dc-ERG but not in the light peak response. Nondiabetic AR -/- mice displayed larger ERG component amplitudes than did nondiabetic WT mice; however, the amplitude of dc-ERG components in diabetic AR -/- animals were similar to WT diabetics. ERG a-wave amplitudes were not reduced in either diabetic group, but b-wave amplitudes were lower in WT and AR -/-diabetic mice. These findings demonstrate that the light-induced responses of the RPE and outer retina are disrupted in diabetic mice, but these defects are not due to photoreceptor dysfunction, nor are they ameliorated by deletion of AR. This latter finding suggests that benefits observed in other studies utilizing pharmacological inhibitors of AR might have been secondary to off-target effects of the drugs.
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1563
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Becker S, Jayaram H, Limb GA. Recent Advances towards the Clinical Application of Stem Cells for Retinal Regeneration. Cells 2012; 1:851-73. [PMID: 24710533 PMCID: PMC3901131 DOI: 10.3390/cells1040851] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Revised: 09/29/2012] [Accepted: 10/10/2012] [Indexed: 01/10/2023] Open
Abstract
Retinal degenerative diseases constitute a major cause of irreversible blindness in the world. Stem cell-based therapies offer hope for these patients at risk of or suffering from blindness due to the deterioration of the neural retina. Various sources of stem cells are currently being investigated, ranging from human embryonic stem cells to adult-derived induced pluripotent stem cells as well as human Müller stem cells, with the first clinical trials to investigate the safety and tolerability of human embryonic stem cell-derived retinal pigment epithelium cells having recently commenced. This review aims to summarize the latest advances in the development of stem cell strategies for the replacement of retinal neurons and their supportive cells, the retinal pigment epithelium (RPE) affected by retinal degenerative conditions. Particular emphasis will be given to the advances in stem cell transplantation and the challenges associated with their translation into clinical practice.
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Affiliation(s)
- Silke Becker
- Ocular Biology and Therapeutics, Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK.
| | - Hari Jayaram
- Ocular Biology and Therapeutics, Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK.
| | - G Astrid Limb
- Ocular Biology and Therapeutics, Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK.
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1564
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Böhm MRR, Melkonyan H, Oellers P, Thanos S. Effects of crystallin-β-b2 on stressed RPE in vitro and in vivo. Graefes Arch Clin Exp Ophthalmol 2012; 251:63-79. [PMID: 23073841 DOI: 10.1007/s00417-012-2157-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Revised: 08/25/2012] [Accepted: 09/03/2012] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Crystallins are thought to play a cytoprotective role in conditions of cellular stress. The aim of this study was to determine the effects of crystallin-β-b2 (cryβ-b2) and crystallin-β-b3 (cryβ-b3) on ARPE-19 cells in vitro and on the retinal pigment epithelium (RPE) in vivo. METHODS The influence of cryβ-b2 and cryβ-b3 on the viability, proliferation and dying of ARPE-19 was measured by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium assay, bromo-2-deoxyuridine assay and life/death assay. The expressions of cryβ-b2, cryβ-b3, glial-derived neurotrophic factor (GDNF), and galectin-3 (Gal-3) in ARPE-19 cells were evaluated using immunohistochemistry (IHC), Western blotting (WB) and real-time-quantitative-PCR (qRT-PCR). To evaluate the response of cryβ-b2 and cryβ-b3 to stressed ARPE-19 cells, the cells were exposed to UV-light. In a rat model, cryβ-b2-expressing neural progenitor cells (cryβ-b2-NPCs) were injected intravitreally after retinal stress induced by optic nerve axotomy to examine whether they influence the RPE. Protein expression was examined 2 and 4 weeks postsurgery using IHC and WB. RESULTS Detectable alterations of GDNF, and Gal-3 were found in ARPE-19 cells upon exposure to UV light. Adding the crystallins to the medium promoted proliferation and increased viability of ARPE-19 cells in vitro. The obtained data support the view that these crystallins possess epithelioprotective properties. Likewise, in vivo, intravitreally injected cryβ-b2 and transplanted cryβ-b2-NPCs protected RPE from indirectly induced stress. CONCLUSIONS The data suggest that the RPE response to retinal ganglion cell denegeration is mediated via crystallins, which may thus be used therapeutically.
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Affiliation(s)
- Michael R R Böhm
- Institute of Experimental Ophthalmology, School of Medicine, Westfalian Wilhelms-University Münster, Albert-Schweitzer-Campus 1, D15, 48149 Münster, Germany.
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1565
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Gestri G, Link BA, Neuhauss SCF. The visual system of zebrafish and its use to model human ocular diseases. Dev Neurobiol 2012; 72:302-27. [PMID: 21595048 DOI: 10.1002/dneu.20919] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Free swimming zebrafish larvae depend mainly on their sense of vision to evade predation and to catch prey. Hence, there is strong selective pressure on the fast maturation of visual function and indeed the visual system already supports a number of visually driven behaviors in the newly hatched larvae.The ability to exploit the genetic and embryonic accessibility of the zebrafish in combination with a behavioral assessment of visual system function has made the zebrafish a popular model to study vision and its diseases.Here, we review the anatomy, physiology, and development of the zebrafish eye as the basis to relate the contributions of the zebrafish to our understanding of human ocular diseases.
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Affiliation(s)
- Gaia Gestri
- Department of Cell and Developmental Biology, University College, London,UK.
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1566
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Cuevas P, Outeiriño LA, Angulo J, Giménez-Gallego G. Treatment of Stargardt disease with dobesilate. BMJ Case Rep 2012; 2012:bcr-2012-007128. [PMID: 23076703 DOI: 10.1136/bcr-2012-007128] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Stargardt disease is a common inherited macular degeneration characterised by a significant loss in the central vision during the first or second decade of the life. Bilateral atrophic changes in the central retina are associated with degeneration of photoreceptors and underlying retinal pigment epithelium, and yellow flecks are extending from the macula. We present a patient with Stargardt disease treated with an intravitreal injection of dobesilate, showing an improvement of visual acuity 4 weeks after treatment.
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Affiliation(s)
- Pedro Cuevas
- Departamento de Investigación, IRYCIS, Hospital Universitario Ramón y Cajal, Madrid, Spain.
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1567
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Onnela N, Lehtonen L, Koski M, Hyttinen J. In vitro electroretinogram for the study of the functionality of differentiated retinal pigment epithelium cells. Med Biol Eng Comput 2012; 51:61-70. [PMID: 23065627 DOI: 10.1007/s11517-012-0968-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Accepted: 09/26/2012] [Indexed: 10/27/2022]
Abstract
The purpose of this study is to develop and test a method to reveal if the retinal pigment epithelium (RPE) cells differentiated from human embryonic stem cells (hESC) support the functions of photoreceptors. hESC-derived RPE (hESC-RPE) cells offer a potent cell source for cell replacement therapy that may be used to prevent certain eye diseases. Methods to assure the functionality of the RPE cells are well warranted. Electroretinograms (ERG) measure the electrophysiological response of the retina to light stimuli. A setup was developed that enables the measurement of ERG in vitro from mice retinas cultured together with hESC-RPE cells. The co-culture of RPE and retinas seems to be a viable tool to assess the functionality of RPE in vitro. However, owing to limited sample size results were somewhat mixed, and thus it was not possible to prove that hESC-RPE cells enhance the ERG response of a mouse retina in vitro. The long-term culturing of the retinas needs to be refined to acquire more conclusive evidence of the supporting role of the RPE and to explore the full potential of the co-culture and ERG methods in assessing RPE functionality.
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Affiliation(s)
- Niina Onnela
- Department of Biomedical Engineering, Tampere University of Technology and BioMediTech, Tampere, Finland.
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1568
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Kaczara P, Zaręba M, Herrnreiter A, Skumatz CMB, Ządło A, Sarna T, Burke JM. Melanosome-iron interactions within retinal pigment epithelium-derived cells. Pigment Cell Melanoma Res 2012; 25:804-14. [PMID: 22883111 DOI: 10.1111/pcmr.12008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 08/07/2012] [Indexed: 01/28/2023]
Abstract
Melanosomes were recently shown to protect ARPE-19 cells, a human retinal pigment epithelium (RPE) cell line, against oxidative stress induced by hydrogen peroxide. One postulated mechanism of antioxidant action of melanin is its ability to bind metal ions. The aim here was to determine whether melanosomes are competent to bind iron within living cells, exhibiting a property previously shown only in model systems. The outcomes indicate retention of prebound iron and accumulation of iron by granules after iron delivery to cells via the culture medium, as determined by both colorimetric and electron spin resonance analyses for bound-to-melanosome iron. Manipulation of iron content did not affect the pigment's ability to protect cells against H(2) O(2) , but the function of pigment granules within RPE cells should be extended beyond a role in light irradiation to include participation in iron homeostasis.
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Affiliation(s)
- Patrycja Kaczara
- Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387, Krakow, Poland
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Westenskow PD, Moreno SK, Krohne TU, Kurihara T, Zhu S, Zhang ZN, Zhao T, Xu Y, Ding S, Friedlander M. Using flow cytometry to compare the dynamics of photoreceptor outer segment phagocytosis in iPS-derived RPE cells. Invest Ophthalmol Vis Sci 2012; 53:6282-90. [PMID: 22871841 DOI: 10.1167/iovs.12-9721] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
PURPOSE Retinal pigment epithelium (RPE) autologous grafts can be readily derived from induced pluripotent stem (iPS) cells. It is critical to stringently characterize iPS-RPE using standardized and quantifiable methods to be confident that they are safe and adequate replacements for diseased RPE before utilizing them in clinical settings. One important and required function is that the iPS-RPE phagocytose photoreceptor outer segments (POS). METHODS We developed a flow cytometry-based assay to monitor binding and internalization of FITC labeled POS by ARPE-19, human fetal RPE (hfRPE), and two types of iPS-RPE. Expression and density of α(v)β₅ integrin, CD36, and MerTK receptors, which are required for phagocytosis, were compared. RESULTS Trypsinization of treated RPE cells results in the release of bound POS. The number of freed POS, the percentage of cells that internalized POS, the brightness of the FITC signal from the cells, and the surface density of the phagocytosis receptors on single RPE cells were measured using flow cytometry. These assays reveal that receptor density is dynamic during differentiation and this can affect the binding and internalization dynamics of the RPE cells. Highly differentiated iPS-RPE phagocytose POS more efficiently than hfRPE. CONCLUSIONS Caution should be exercised to not use RPE grafts until demonstrating that they are fully functional. The density of the phagocytosis receptors is dynamic and may be used as a predictor for how well the iPS-RPE cells will function in vivo. The phagocytosis dynamics observed between iPS-RPE and primary RPE is very encouraging and adds to mounting evidence that iPS-RPE may be a viable replacement for dysfunctional or dying RPE in human patients.
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Affiliation(s)
- Peter D Westenskow
- Department of Cell Biology, The Scripps Research Institute, La Jolla, California, USA
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1570
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Zhang Y, Liu Y, Wildsoet CF. Bidirectional, optical sign-dependent regulation of BMP2 gene expression in chick retinal pigment epithelium. Invest Ophthalmol Vis Sci 2012; 53:6072-80. [PMID: 22879416 DOI: 10.1167/iovs.12-9917] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
PURPOSE We explored the role of bone morphogenic protein 2 (BMP2) in defocus-induced ocular growth using gene expression changes in RPE as a surrogate. METHODS Young White-Leghorn chickens were used in this study. Normal gene expression of BMP2 and its receptors was examined in retina, RPE, and choroid, and BMP2 protein expression assessed in the same tissues using Western blots and immunohistochemistry. Quantitative PCR (qPCR) was used to assess the effects of short-term exposure (2 or 48 hours) to monocular +10 and -10 diopter (D) lenses, on RPE gene expression of BMP2 and its receptors. Ocular growth was assessed using A-scan ultrasonography. RESULTS In the eyes of untreated chickens, BMP2 mRNA was expressed more highly in RPE compared to retina and choroid and all three tissues expressed BMP2 protein. The gene expression for all three receptors also was detected in these tissues, with BMPR2 showing highest and BMPR1B lowest expression. BMP2 was up-regulated in the RPE from eyes wearing +10 D lenses, which exhibited shorter than normal vitreous chambers (VCDs) and thickened choroids, while BMP2 was down-regulated in the RPE from eyes wearing -10 D lenses, which developed enlarged VCDs. These treatments did not induce differential expression of BMP receptors in RPE. CONCLUSIONS That mRNA expression of BMP2 in chick RPE shows bidirectional, defocus sign-dependent changes is suggestive of a role for BMP2 in eye growth regulation, although the diffuse ocular expression of BMP2 and its receptors suggests complex growth-modulatory signal pathways.
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Affiliation(s)
- Yan Zhang
- Center for Eye Disease & Development, Vision Science Program & School of Optometry, University of California, Berkeley, Berkeley, California 94720, USA.
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1571
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Koutsonas A, Carstesen D, Henkel C, Walter P, Thumann G, Weinberger AWA. Effects of coagulation on the autofluorescence pattern of ARPE-19 cells: an in vitro study. Ophthalmic Res 2012; 49:11-9. [PMID: 22964483 DOI: 10.1159/000341740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 06/13/2012] [Indexed: 11/19/2022]
Abstract
OBJECTIVE Changes in fundus autofluorescence (AF) are observed in various retinal disorders. Lipofuscin accumulation within the retinal pigment epithelium (RPE) is a source of fundus AF (FAF); however, the causes of short-term increases in FAF observed in inflammatory conditions or after laser treatment are unknown. Here, we describe an RPE cell culture model that is useful for investigations of FAF. METHODS ARPE-19 cells were cultured in 2-well chamber slides. Cells were exposed to isolated rabbit photoreceptor outer segments (POS) to mimic in vivo phagocytic activity. The AF of RPE cells exposed to POS was measured before and after focal coagulation of the cultures. AF was measured over a period of 4 weeks. Cell lysates were examined by two-dimensional (2D) gel electrophoresis and mass spectrometry analysis. RESULTS The exposure of ARPE cells to POS did not lead to increased AF; however, after coagulation, cells exposed to POS showed a statistically significant increase in AF (p < 0.05). 2D electrophoresis of the cell lysates revealed changes in 3 proteins. One of these proteins, identified by mass spectrometry as ezrin-radixin-moesin-binding phosphoprotein 50, was reduced in the coagulated cell population. CONCLUSIONS We have established an in vitro model of RPE cells in culture that can be used to evaluate the development of AF and changes in cellular proteins that accompany laser photocoagulation.
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Affiliation(s)
- Antonis Koutsonas
- Department of Ophthalmology, RWTH Aachen University, Aachen, Germany.
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1572
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Cho MS, Kim SJ, Ku SY, Park JH, Lee H, Yoo DH, Park UC, Song SA, Choi YM, Yu HG. Generation of retinal pigment epithelial cells from human embryonic stem cell-derived spherical neural masses. Stem Cell Res 2012; 9:101-9. [PMID: 22683799 DOI: 10.1016/j.scr.2012.05.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Revised: 04/06/2012] [Accepted: 05/08/2012] [Indexed: 10/28/2022] Open
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Sahni JN, Angi M, Irigoyen C, Semeraro F, Romano MR, Parmeggiani F. Therapeutic challenges to retinitis pigmentosa: from neuroprotection to gene therapy. Curr Genomics 2012; 12:276-84. [PMID: 22131873 PMCID: PMC3131735 DOI: 10.2174/138920211795860062] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 04/08/2011] [Accepted: 04/18/2011] [Indexed: 12/12/2022] Open
Abstract
Syndromic retinitis pigmentosa (RP) is the result of several mutations expressed in rod photoreceptors, over 40 of which have so far been identified. Enormous efforts are being made to relate the advances in unraveling the patho-physiological mechanisms to therapeutic approaches in animal models, and eventually in clinical trials on humans. This review summarizes briefly the current clinical management of RP and focuses on the new exciting treatment possibilities. To date, there is no approved therapy able to stop the evolution of RP or restore vision. The current management includes an attempt at slowing down the degenerative process by vitamin supplementation, trying to treat ocular complications and to provide psychological support to blind patients. Novel therapeutic may be tailored dependant on the stage of the disease and can be divided in three groups. In the early stages, when there are surviving photoreceptors, the first approach would be to try to halt the degeneration by correction of the underlying biochemical abnormality in the visual cycle using gene therapy or pharmacological treatment. A second approach aims to cope with photoreceptor cell death using neurotrophic growth factors or anti-apoptotic factors, reducing the production of retino-toxic molecules, and limiting oxidative damage. In advanced stages, when there are few or no functional photoreceptors, strategies that may benefit include retinal transplantation, electronic retinal implants or a newly described optogenetic technique using a light-activated channel to genetically resensitize remnant cone-photoreceptor cells.
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Affiliation(s)
- Jayashree N Sahni
- St. Paul's Eye Unit, Royal Liverpool University Hospital, Liverpool, UK
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1574
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MicroRNA-30b-mediated regulation of catalase expression in human ARPE-19 cells. PLoS One 2012; 7:e42542. [PMID: 22880027 PMCID: PMC3412823 DOI: 10.1371/journal.pone.0042542] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Accepted: 07/09/2012] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Oxidative injury to retinal pigment epithelium (RPE) and retinal photoreceptors has been linked to a number of retinal diseases, including age-related macular degeneration (AMD). Reactive oxygen species (ROS)-mediated gene expression has been extensively studied at transcriptional levels. Also, the post-transcriptional control of gene expression at the level of translational regulation has been recently reported. However, the microRNA (miRNA/miR)-mediated post-transcriptional regulation in human RPE cells has not been thoroughly looked at. Increasing evidence points to a potential role of miRNAs in diverse physiological processes. METHODOLOGY/PRINCIPAL FINDINGS We demonstrated for the first time in a human retinal pigment epithelial cell line (ARPE-19) that the post-transcriptional control of gene expression via miRNA modulation regulates human catalase, an important and potent component of cell's antioxidant defensive network, which detoxifies hydrogen peroxide (H(2)O(2)) radicals. Exposure to several stress-inducing agents including H(2)O(2) has been reported to alter miRNA expression profile. Here, we demonstrated that a sublethal dose of H(2)O(2) (200 µM) up-regulated the expression of miR-30b, a member of the miR-30 family, which inhibited the expression of endogenous catalase both at the transcript and protein levels. However, antisense (antagomirs) of miR-30b was not only found to suppress the miR-30b mimics-mediated inhibitions, but also to dramatically increase the expression of catalase even under an oxidant environment. CONCLUSIONS/SIGNIFICANCE We propose that a microRNA antisense approach could enhance cytoprotective mechanisms against oxidative stress by increasing the antioxidant defense system.
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1575
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Localization of acetylcholine-related molecules in the retina: implication of the communication from photoreceptor to retinal pigment epithelium. PLoS One 2012; 7:e42841. [PMID: 22880119 PMCID: PMC3411837 DOI: 10.1371/journal.pone.0042841] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Accepted: 07/11/2012] [Indexed: 01/08/2023] Open
Abstract
It has been long speculated that specific signals are transmitted from photoreceptors to the retinal pigment epithelium (RPE). However, such signals have not been identified. In this study, we examined the retinal expression and localization of acetylcholine-related molecules as putative candidates for these signals. Previous reports revealed that α7 nicotinic acetylcholine receptors (nAChRs) are present in the microvilli of RPE cells that envelope the tips of photoreceptor outer segments (OS). Secreted mammalian leukocyte antigen 6/urokinase-type plasminogen activator receptor-related protein-1 (SLURP-1) is a positive allosteric modulator of the α7 nAChR. Therefore, we first focused on the expression of SLURP-1. SLURP-1 mRNA was expressed in the outer nuclear layer, which is comprised of photoreceptor cell bodies. SLURP-1 immunoreactivity co-localized with rhodopsin and S-opsin in photoreceptor OS, while choline acetyltransferase (ChAT) and high affinity choline transporter (CHT-1) were also expressed in photoreceptor OS. Immunoelectron microscopy identified that the majority of SLURP-1 was localized to the plasma membranes of photoreceptor OS. These results provide evidence that SLURP-1 is synthesized in photoreceptor cell bodies and transported to photoreceptor OS, where SLURP-1 may also be secreted. Our findings suggest that photoreceptor OS communicate via neurotransmitters such as ACh and SLURP-1, while RPE cells might receive these signals through α7 nAChRs in their microvilli.
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Abstract
The original hedgehog (hh) gene was found in Drosophila and named for the appearance of a mutant phenotype which causes an embryo to be covered with pointy denticles, thus resembling a hedgehog. The hedgehog family consists of sonic hedgehog (Shh), desert hedgehog (Dhh), and Indian hedgehog (Ihh). Shh is found in vertebrates and the best studied ligand of the hedgehog signaling pathway (Gilbert, 2000). It plays an important role in regulating vertebrate organogenesis, such as in the growth of digits on limbs and organization of the brain, and earlier studies also show that it is important during retinal development (for a review, see Amato et al., 2004). Hedgehog expression drives waves of neurogenesis in animal retina, although genetic programs that control its expression are poorly elucidated. Recently, a novel transcriptional cascade which involves the atonal and Iroquois gene family was proposed in the regulation of hedgehog waves during vertebrate retinal development (Choy et al., 2010). This chapter will focus on Shh by addressing its signaling mechanisms and roles in vertebrate eye development, as well as a novel finding in retinogenesis.
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Lapan SW, Reddien PW. Transcriptome analysis of the planarian eye identifies ovo as a specific regulator of eye regeneration. Cell Rep 2012; 2:294-307. [PMID: 22884275 DOI: 10.1016/j.celrep.2012.06.018] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 05/12/2012] [Accepted: 06/22/2012] [Indexed: 11/24/2022] Open
Abstract
Among the millions of invertebrate species with visual systems, the genetic basis of eye development and function is well understood only in Drosophila melanogaster. We describe an eye transcriptome for the planarian Schmidtea mediterranea. Planarian photoreceptors expressed orthologs of genes required for phototransduction and microvillus structure in Drosophila and vertebrates, and optic pigment cells expressed solute transporters and melanin synthesis enzymes similar to those active in the vertebrate retinal pigment epithelium. Orthologs of several planarian eye genes, such as bestrophin-1 and Usher syndrome genes, cause eye defects in mammals when perturbed and were not previously described to have roles in invertebrate eyes. Five previously undescribed planarian eye transcription factors were required for normal eye formation during head regeneration. In particular, a conserved, transcription-factor-encoding ovo gene was expressed from the earliest stages of eye regeneration and was required for regeneration of all cell types of the eye.
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Affiliation(s)
- Sylvain W Lapan
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
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1578
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Mizuno A, Yasumuro H, Yoshikawa T, Inami W, Chiba C. MEK–ERK signaling in adult newt retinal pigment epithelium cells is strengthened immediately after surgical induction of retinal regeneration. Neurosci Lett 2012; 523:39-44. [DOI: 10.1016/j.neulet.2012.06.037] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Accepted: 06/13/2012] [Indexed: 02/04/2023]
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1579
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Hu G, Huang K, Yu J, Gopalakrishna-Pillai S, Kong J, Xu H, Liu Z, Zhang K, Xu J, Luo Y, Li S, Sun YE, Iverson LE, Xue Z, Fan G. Identification of miRNA signatures during the differentiation of hESCs into retinal pigment epithelial cells. PLoS One 2012; 7:e37224. [PMID: 22848339 PMCID: PMC3407211 DOI: 10.1371/journal.pone.0037224] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Accepted: 04/16/2012] [Indexed: 01/10/2023] Open
Abstract
Retinal pigment epithelium (RPE) cells can be obtained through in vitro differentiation of both embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). We have previously identified 87 signature genes relevant to RPE cell differentiation and function through transcriptome analysis of both human ESC- and iPSC-derived RPE as well as normal fetal RPE. Here, we profile miRNA expression through small RNA-seq in human ESCs and their RPE derivatives. Much like conclusions drawn from our previous transcriptome analysis, we find that the overall miRNA landscape in RPE is distinct from ESCs and other differentiated somatic tissues. We also profile miRNA expression during intermediate stages of RPE differentiation and identified unique subsets of miRNAs that are gradually up- or down-regulated, suggesting that dynamic regulation of these miRNAs is associated with the RPE differentiation process. Indeed, the down-regulation of a subset of miRNAs during RPE differentiation is associated with up-regulation of RPE-specific genes, such as RPE65, which is exclusively expressed in RPE. We conclude that miRNA signatures can be used to classify different degrees of in vitro differentiation of RPE from human pluripotent stem cells. We suggest that RPE-specific miRNAs likely contribute to the functional maturation of RPE in vitro, similar to the regulation of RPE-specific mRNA expression.
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Affiliation(s)
- Ganlu Hu
- Translational Center for Stem Cell Research, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
- Stem Cell Research Center, Department of Regenerative Medicine, Tongji University School of Medicine, Shanghai, China
| | - Kevin Huang
- Department of Human Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Juehua Yu
- Department of Human Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | | | - Jun Kong
- Department of Human Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - He Xu
- Department of Human Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Zhenshan Liu
- Stem Cell Research Center, Department of Regenerative Medicine, Tongji University School of Medicine, Shanghai, China
| | - Kunshan Zhang
- Stem Cell Research Center, Department of Regenerative Medicine, Tongji University School of Medicine, Shanghai, China
| | - Jun Xu
- Stem Cell Research Center, Department of Regenerative Medicine, Tongji University School of Medicine, Shanghai, China
| | - Yuping Luo
- Stem Cell Research Center, Department of Regenerative Medicine, Tongji University School of Medicine, Shanghai, China
| | - Siguang Li
- Stem Cell Research Center, Department of Regenerative Medicine, Tongji University School of Medicine, Shanghai, China
| | - Yi E. Sun
- Translational Center for Stem Cell Research, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
- Stem Cell Research Center, Department of Regenerative Medicine, Tongji University School of Medicine, Shanghai, China
| | - Linda E. Iverson
- Stem Cell Biology, Beckman Research Institute of City of Hope, Duarte, California, United States of America
| | - Zhigang Xue
- Translational Center for Stem Cell Research, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
- Stem Cell Research Center, Department of Regenerative Medicine, Tongji University School of Medicine, Shanghai, China
- * E-mail: (GF); (ZX)
| | - Guoping Fan
- Stem Cell Research Center, Department of Regenerative Medicine, Tongji University School of Medicine, Shanghai, China
- Department of Human Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail: (GF); (ZX)
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Stewart MW. Clinical and differential utility of VEGF inhibitors in wet age-related macular degeneration: focus on aflibercept. Clin Ophthalmol 2012; 6:1175-86. [PMID: 22973088 PMCID: PMC3422153 DOI: 10.2147/opth.s33372] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Age-related macular degeneration (AMD) has become a major public health problem and a leading cause of blindness in industrialized nations. AMD results from the ageing eye's inability to metabolize and dispose completely of photoreceptor outer segments and other waste products. As a result, lipids, particularly apolipoproteins, accumulate within Bruch's membrane, leading to chronic ischemia and inflammation. The subsequent upregulation of inflammatory cytokines and growth factors, including vascular endothelial growth factor (VEGF), induces the growth of neovascular membranes from the choriocapillaris into the subretinal or subretinal pigment epithelium spaces. To counter this, intravitreally administered drugs (pegaptanib, bevacizumab, ranibizumab) that specifically target VEGF have become the standard treatment for exudative AMD. Aflibercept, a recently approved fusion protein, binds to all isoforms of both VEGF-A and placental growth factor with high affinity. Phase III trials showed that monthly or every other month injections of aflibercept prevent vision loss (fewer than 15 letters) in 95% of patients. Additionally, aflibercept injections every 4 or 8 weeks produce average vision gains of 6.9 letters to 10.9 letters, comparable with those achieved with monthly ranibizumab. After one year of regularly administered aflibercept injections, patients required an average of only 4.2 injections during the second year. Aflibercept promises to decrease the injection frequency required for many patients and appears to serve as an effective "salvage" therapy for patients who respond poorly to other anti-VEGF drugs.
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1581
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Omarova S, Charvet CD, Reem RE, Mast N, Zheng W, Huang S, Peachey NS, Pikuleva IA. Abnormal vascularization in mouse retina with dysregulated retinal cholesterol homeostasis. J Clin Invest 2012; 122:3012-23. [PMID: 22820291 DOI: 10.1172/jci63816] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 05/24/2012] [Indexed: 11/17/2022] Open
Abstract
Several lines of evidence suggest a link between age-related macular degeneration and retinal cholesterol maintenance. Cytochrome P450 27A1 (CYP27A1) is a ubiquitously expressed mitochondrial sterol 27-hydroxylase that plays an important role in the metabolism of cholesterol and cholesterol-related compounds. We conducted a comprehensive ophthalmic evaluation of mice lacking CYP27A1. We found that the loss of CYP27A1 led to dysregulation of retinal cholesterol homeostasis, including unexpected upregulation of retinal cholesterol biosynthesis. Cyp27a1-/- mice developed retinal lesions characterized by cholesterol deposition beneath the retinal pigment epithelium. Further, Cyp27a1-null mice showed pathological neovascularization, which likely arose from both the retina and the choroid, that led to the formation of retinal-choroidal anastomosis. Blood flow alterations and blood vessel leakage were noted in the areas of pathology. The Cyp27a1-/- retina was hypoxic and had activated Müller cells. We suggest a mechanism whereby abolished sterol 27-hydroxylase activity leads to vascular changes and identify Cyp27a1-/- mice as a model for one of the variants of type 3 retinal neovascularization occurring in some patients with age-related macular degeneration.
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Affiliation(s)
- Saida Omarova
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH 44106, USA
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1582
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Phenotypic plasticity of retinal pigment epithelial cells from adult human eye in vitro. Bull Exp Biol Med 2012; 151:506-11. [PMID: 22448378 DOI: 10.1007/s10517-011-1368-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Phenotypic plasticity of retinal pigment epithelial cells from adult human eye was studied by immunohistochemical methods under different culturing conditions. It was found that retinal pigment epithelium in adult human eye is a heterogeneous population of cells demonstrating different behavior in vitro. Some cells retain epithelial morphology for a long time in culture, while others are rapidly transformed into fibroblast-like cells and synthesize proteins typical of proneural, neural, glial, and photoreceptor cells. However, irrespective of initial morphological features differentiation of retinal pigment cells can be modulated by varying culturing conditions.
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1583
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Mustafi D, Maeda T, Kohno H, Nadeau JH, Palczewski K. Inflammatory priming predisposes mice to age-related retinal degeneration. J Clin Invest 2012; 122:2989-3001. [PMID: 22797304 DOI: 10.1172/jci64427] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Accepted: 06/07/2012] [Indexed: 12/22/2022] Open
Abstract
Disruption of cellular processes affected by multiple genes and accumulation of numerous insults throughout life dictate the progression of age-related disorders, but their complex etiology is poorly understood. Postmitotic neurons, such as photoreceptor cells in the retina and epithelial cells in the adjacent retinal pigmented epithelium, are especially susceptible to cellular senescence, which contributes to age-related retinal degeneration (ARD). The multigenic and complex etiology of ARD in humans is reflected by the relative paucity of effective compounds for its early prevention and treatment. To understand the genetic differences that drive ARD pathogenesis, we studied A/J mice, which develop ARD more pronounced than that in other inbred mouse models. Although our investigation of consomic strains failed to identify a chromosome associated with the observed retinal deterioration, pathway analysis of RNA-Seq data from young mice prior to retinal pathological changes revealed that increased vulnerability to ARD in A/J mice was due to initially high levels of inflammatory factors and low levels of homeostatic neuroprotective factors. The genetic signatures of an uncompensated preinflammatory state and ARD progression identified here aid in understanding the susceptible genetic loci that underlie pathogenic mechanisms of age-associated disorders, including several human blinding diseases.
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Affiliation(s)
- Debarshi Mustafi
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA
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1584
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Abstract
The human eye is constantly exposed to sunlight and artificial lighting. Light transmission through the eye is fundamental to its unique biological functions of directing vision and circadian rhythm and therefore light absorbed by the eye must be benign. However, exposure to the very intense ambient radiation can pose a hazard particularly if the recipient is over 40 years of age. There are age-related changes in the endogenous (natural) chromophores (lipofuscin, A2E and all-trans-retinal derivatives) in the human retina that makes it more susceptible to visible light damage. Intense visible light sources that do not filter short blue visible light (400-440 nm) used for phototherapy of circadian imbalance (i.e. seasonal affective disorder) increase the risk for age-related light damage to the retina. Moreover, many drugs, dietary supplements, nanoparticles and diagnostic dyes (xenobiotics) absorb ocular light and have the potential to induce photodamage to the retina, leading to transient or permanent blinding disorders. This article will review the underlying reasons why visible light in general and short blue visible light in particular dramatically raises the risk of photodamage to the human retina.
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Affiliation(s)
- Albert R Wielgus
- Department of Ophthalmology, Duke University Medical Center, Durham, NC, USA
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1585
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Ultrastructure of the human retina in aging and various pathological states. Micron 2012; 43:759-81. [DOI: 10.1016/j.micron.2012.01.011] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Accepted: 01/24/2012] [Indexed: 11/22/2022]
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1586
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Guha S, Baltazar GC, Tu LA, Liu J, Lim JC, Lu W, Argall A, Boesze-Battaglia K, Laties AM, Mitchell CH. Stimulation of the D5 dopamine receptor acidifies the lysosomal pH of retinal pigmented epithelial cells and decreases accumulation of autofluorescent photoreceptor debris. J Neurochem 2012; 122:823-33. [PMID: 22639870 DOI: 10.1111/j.1471-4159.2012.07804.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Optimal neuronal activity requires that supporting cells provide both efficient nutrient delivery and waste disposal. The incomplete processing of engulfed waste by their lysosomes can lead to accumulation of residual material and compromise their support of neurons. As most degradative lysosomal enzymes function best at an acidic pH, lysosomal alkalinization can impede enzyme activity and increase lipofuscin accumulation. We hypothesize that treatment to reacidify compromised lysosomes can enhance degradation. Here, we demonstrate that degradation of ingested photoreceptor outer segments by retinal pigmented epithelial cells is increased by stimulation of D5 dopamine receptors. D1/D5 receptor agonists reacidified lysosomes in cells alkalinized by chloroquine or tamoxifen, with acidification dependent on protein kinase A. Knockdown with siRNA confirmed acidification was mediated by the D5 receptor. Exposure of cells to outer segments increased lipofuscin-like autofluorescence, but SKF 81297 reduced autofluorescence. Likewise, SKF 81297 increased the activity of lysosomal protease cathepsin D in situ. D5DR stimulation also acidified lysosomes of retinal pigmented epithelial cells from elderly ABCA4(-/-) mice, a model of recessive Stargardt's retinal degeneration. In conclusion, D5 receptor stimulation lowers compromised lysosomal pH, enhancing degradation. The reduced accumulation of lipofuscin-like autofluorescence implies the D5 receptor stimulation may enable cells to better support adjacent neurons.
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Affiliation(s)
- Sonia Guha
- Department of Anatomy and Cell Biology, University of Pennsylvania, PA, USA
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1587
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Zhang Q, Liu Q, Austin C, Drummond I, Pierce EA. Knockdown of ttc26 disrupts ciliogenesis of the photoreceptor cells and the pronephros in zebrafish. Mol Biol Cell 2012; 23:3069-78. [PMID: 22718903 PMCID: PMC3418303 DOI: 10.1091/mbc.e12-01-0019] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The article describes characterization of the cilia protein Ttc26. The data show that Ttc26 is localized in the transition zone of primary cilia and photoreceptor cells. Knockdown of Ttc26 produced defective cilia in murine inner medullary collecting duct 3 cells and ciliogenesis defects in retinal photoreceptor and motile cilia in the pronephros in zebrafish. In our effort to understand genetic disorders of the photoreceptor cells of the retina, we have focused on intraflagellar transport in photoreceptor sensory cilia. From previous mouse proteomic data we identified a cilia protein Ttc26, orthologue of dyf-13 in Caenorhabditis elegans, as a target. We localized Ttc26 to the transition zone of photoreceptor and to the transition zone of cilia in cultured murine inner medullary collecting duct 3 (mIMCD3) renal cells. Knockdown of Ttc26 in mIMCD3 cells produced shortened and defective primary cilia, as revealed by immunofluorescence and scanning electron microscopy. To study Ttc26 function in sensory cilia in vivo, we utilized a zebrafish vertebrate model system. Morpholino knockdown of ttc26 in zebrafish embryos caused ciliary defects in the pronephric kidney at 27 h postfertilization and distension/dilation of pronephros at 5 d postfertilization (dpf). In the eyes, the outer segments of photoreceptor cells appeared shortened or absent, whereas cellular lamination appeared normal in retinas at 5 dpf. This suggests that loss of ttc26 function prevents normal ciliogenesis and differentiation in the photoreceptor cells, and that ttc26 is required for normal development and differentiation in retina and pronephros. Our studies support the importance of Ttc26 function in ciliogenesis and suggest that screening for TTC26 mutations in human ciliopathies is justified.
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Affiliation(s)
- Qi Zhang
- Ocular Genomics Institute & Berman-Gund Laboratory, Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA 02114, USA
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1588
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Zhour A, Bolz S, Grimm C, Willmann G, Schatz A, Weber BHF, Zrenner E, Fischer MD. In vivo imaging reveals novel aspects of retinal disease progression in Rs1h−/Y mice but no therapeutic effect of carbonic anhydrase inhibition. Vet Ophthalmol 2012; 15 Suppl 2:123-33. [DOI: 10.1111/j.1463-5224.2012.01039.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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1589
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Derivation, culture and retinal pigment epithelial differentiation of human embryonic stem cells using human fibroblast feeder cells. J Assist Reprod Genet 2012; 29:735-44. [PMID: 22661130 DOI: 10.1007/s10815-012-9802-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Accepted: 05/20/2012] [Indexed: 01/08/2023] Open
Abstract
PURPOSE Retinal pigment epithelium cells derived from human embryonic stem cells (ESCs) could be useful for restoring retinal function in age-related macular degeneration. However the use of non-human feeder cells to support the growth of ESCs for clinical applications raises the concern of possible contamination because of direct contact between animal and human cells. METHODS In this study, we produced human ESCs using human fibroblast feeder layers isolated from foreskin and abdominal tissues. Using this system, human ESCs differentiated into retinal pigment epithelium cells in differentiation medium. RESULTS Seven human ESC lines were established from 18 blastocysts. These human ESCs showed normal morphology, expressed all expected cell surface markers, had the ability to form embryoid bodies upon culture in vitro and teratomas after injection into SCID mice, and differentiated further into derivatives of all three germ layers. Under conditions of committed differentiation, these human ESCs could differentiate into retinal pigment epithelium cells after 2 months in culture. CONCLUSIONS The results of this study demonstrated that human foreskin/abdominal fibroblasts have the potential to support the derivation and long-term culture of human ESCs, which can then be used to generate retinal pigment epithelium cells with characteristic morphology and molecular markers. This technique avoids the concerns of contamination from animal feeder layers during human ESC derivation, culture and differentiation, and will thus facilitate the development of retinal pigment epithelium cell transplantation therapy.
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1590
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Shadforth AM, George KA, Kwan AS, Chirila TV, Harkin DG. The cultivation of human retinal pigment epithelial cells on Bombyx mori silk fibroin. Biomaterials 2012; 33:4110-7. [DOI: 10.1016/j.biomaterials.2012.02.040] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2012] [Accepted: 02/23/2012] [Indexed: 11/25/2022]
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1591
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Kinnunen K, Petrovski G, Moe MC, Berta A, Kaarniranta K. Molecular mechanisms of retinal pigment epithelium damage and development of age-related macular degeneration. Acta Ophthalmol 2012; 90:299-309. [PMID: 22112056 DOI: 10.1111/j.1755-3768.2011.02179.x] [Citation(s) in RCA: 144] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Age-related macular degeneration (AMD) is attributed to a complex interaction of genetic and environmental factors. It is characterized by degeneration involving the retinal photoreceptors, retinal pigment epithelium (RPE) and Bruch's membrane, as well as alterations in choroidal capillaries. AMD pathogenesis is strongly associated with chronic oxidative stress and inflammation that ultimately lead to protein damage, aggregation and degeneration of RPE. Specific degenerative findings for AMD are accumulation of intracellular lysosomal lipofuscin and extracellular drusens. In this review, we discuss thoroughly RPE-derived mechanisms in AMD pathology.
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Affiliation(s)
- Kati Kinnunen
- Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland
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1592
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Ueta T, Inoue T, Yuda K, Furukawa T, Yanagi Y, Tamaki Y. Intense physiological light upregulates vascular endothelial growth factor and enhances choroidal neovascularization via peroxisome proliferator-activated receptor γ coactivator-1α in mice. Arterioscler Thromb Vasc Biol 2012; 32:1366-71. [PMID: 22516064 DOI: 10.1161/atvbaha.112.248021] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Toxicity of intense light to facilitate the development of neovascular age-related macular degeneration has been a health concern although the mechanism remains unclear. METHODS AND RESULTS Effects of intense, but within physiological range, light on retinal pigment epithelium, a major pathogenic origin of age-related macular degeneration were studied in mice. Intense physiological light upregulated vascular endothelial growth factor (VEGF) expression in retinal pigment epithelium, independent of circadian rhythm, which resulted in enhancement of choroidal neovascularization. In rd1/rd1 mice or Crx(-/-) mice that do not possess outer segment structure, light exposure did not induce VEGF, indicating that VEGF upregulation by light depended on increased outer segment phagocytosis by retinal pigment epithelium. In retinal pigment epithelium cells phagocytosing increased amount of outer segment, peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) not hypoxia-inducible factor-1α was induced, leading to VEGF upregulation. The VEGF upregulation and choroidal neovascularization enhancement were abrogated in PGC-1α(-/-) mice and estrogen-related receptor-α(-/-) mice, indicating the involvement of PGC-1α/estrogen-related receptor-α pathway. CONCLUSIONS Intense physiological light is involved in choroidal neovascularization through excess outer segment phagocytosis and VEGF upregulation mediated by PGC-1α in vivo.
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Affiliation(s)
- Takashi Ueta
- Department of Ophthalmology, University of Tokyo School of Medicine, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
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1593
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Chucair-Elliott AJ, Elliott MH, Wang J, Moiseyev GP, Ma JX, Politi LE, Rotstein NP, Akira S, Uematsu S, Ash JD. Leukemia inhibitory factor coordinates the down-regulation of the visual cycle in the retina and retinal-pigmented epithelium. J Biol Chem 2012; 287:24092-102. [PMID: 22645143 DOI: 10.1074/jbc.m112.378240] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Leukemia inhibitory factor (LIF), an interleukin-6 family neurocytokine, is up-regulated in response to different types of retinal stress and has neuroprotective activity through activation of the gp130 receptor/STAT3 pathway. We observed that LIF induces rapid, robust, and sustained activation of STAT3 in both the retina and retinal pigmented epithelium (RPE). Here, we tested whether LIF-induced STAT3 activation within the RPE can down-regulate RPE65, the central enzyme in the visual cycle that provides the 11-cis-retinal chromophore to photoreceptors in vivo. We generated conditional knock-out mice to specifically delete STAT3 or gp130 in RPE, retina, or both RPE and retina. After intravitreal injection of LIF, we analyzed the expression levels of visual cycle genes and proteins, isomerase activity of RPE65, levels of rhodopsin protein, and the rates of dark adaptation and rhodopsin regeneration. We found that RPE65 protein levels and isomerase activity were reduced and recovery of bleachable rhodopsin was delayed in LIF-injected eyes. In mice with functional gp130/STAT3 signaling in the retina, rhodopsin protein was also reduced by LIF. However, the LIF-induced down-regulation of RPE65 required a functional gp130/STAT3 cascade intrinsic to RPE. Our data demonstrate that a single cytokine, LIF, can simultaneously and independently affect both RPE and photoreceptors through the same signaling cascade to reduce the generation and utilization of 11-cis-retinal.
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Affiliation(s)
- Ana J Chucair-Elliott
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
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1594
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Hollborn M, Rehak M, Iandiev I, Pannicke T, Ulbricht E, Reichenbach A, Wiedemann P, Bringmann A, Kohen L. Transcriptional Regulation of Aquaporins in the Ischemic Rat Retina: Upregulation of Aquaporin-9. Curr Eye Res 2012; 37:524-31. [DOI: 10.3109/02713683.2012.658133] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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1595
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Selective activation of p120ctn-Kaiso signaling to unlock contact inhibition of ARPE-19 cells without epithelial-mesenchymal transition. PLoS One 2012; 7:e36864. [PMID: 22590627 PMCID: PMC3348893 DOI: 10.1371/journal.pone.0036864] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 04/15/2012] [Indexed: 11/19/2022] Open
Abstract
Contact-inhibition ubiquitously exists in non-transformed cells and explains the poor regenerative capacity of in vivo human retinal pigment epithelial cells (RPE) during aging, injury and diseases. RPE injury or degeneration may unlock mitotic block mediated by contact inhibition but may also promote epithelial-mesenchymal transition (EMT) contributing to retinal blindness. Herein, we confirmed that EMT ensued in post-confluent ARPE-19 cells when contact inhibition was disrupted with EGTA followed by addition of EGF and FGF-2 because of activation of canonical Wnt and Smad/ZEB signaling. In contrast, knockdown of p120-catenin (p120) unlocked such mitotic block by activating p120/Kaiso, but not activating canonical Wnt and Smad/ZEB signaling, thus avoiding EMT. Nuclear BrdU labeling was correlated with nuclear release of Kaiso through p120 nuclear translocation, which was associated with activation of RhoA-ROCK signaling, destabilization of microtubules. Prolonged p120 siRNA knockdown followed by withdrawal further expanded RPE into more compact monolayers with a normal phenotype and a higher density. This new strategy based on selective activation of p120/Kaiso but not Wnt/β-catenin signaling obviates the need of using single cells and the risk of EMT, and may be deployed to engineer surgical grafts containing RPE and other tissues.
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1596
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Shaham O, Menuchin Y, Farhy C, Ashery-Padan R. Pax6: a multi-level regulator of ocular development. Prog Retin Eye Res 2012; 31:351-76. [PMID: 22561546 DOI: 10.1016/j.preteyeres.2012.04.002] [Citation(s) in RCA: 160] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 04/19/2012] [Accepted: 04/24/2012] [Indexed: 02/08/2023]
Abstract
Eye development has been a paradigm for the study of organogenesis, from the demonstration of lens induction through epithelial tissue morphogenesis, to neuronal specification and differentiation. The transcription factor Pax6 has been shown to play a key role in each of these processes. Pax6 is required for initiation of developmental pathways, patterning of epithelial tissues, activation of tissue-specific genes and interaction with other regulatory pathways. Herein we examine the data accumulated over the last few decades from extensive analyses of biochemical modules and genetic manipulation of the Pax6 gene. Specifically, we describe the regulation of Pax6's expression pattern, the protein's DNA-binding properties, and its specific roles and mechanisms of action at all stages of lens and retinal development. Pax6 functions at multiple levels to integrate extracellular information and execute cell-intrinsic differentiation programs that culminate in the specification and differentiation of a distinct ocular lineage.
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Affiliation(s)
- Ohad Shaham
- Sackler Faculty of Medicine, Department of Human Molecular Genetics and Biochemistry, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel
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1597
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Wohl SG, Schmeer CW, Isenmann S. Neurogenic potential of stem/progenitor-like cells in the adult mammalian eye. Prog Retin Eye Res 2012; 31:213-42. [DOI: 10.1016/j.preteyeres.2012.02.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Revised: 02/04/2012] [Accepted: 02/06/2012] [Indexed: 11/26/2022]
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1598
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Chen HC, Zhu YT, Chen SY, Tseng SCG. Wnt signaling induces epithelial-mesenchymal transition with proliferation in ARPE-19 cells upon loss of contact inhibition. J Transl Med 2012; 92:676-87. [PMID: 22391957 PMCID: PMC3961713 DOI: 10.1038/labinvest.2011.201] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Proliferation and epithelial-mesenchymal transition (EMT) of the retinal pigment epithelium (RPE) are hallmarks of proliferative vitreoretinopathy. This study aims at clarifying the role of growth factors, such as epidermal growth factor (EGF), fibroblast growth factor-2 (FGF-2), and transforming growth factor-β1 (TGF-β1), in controlling how RPE proliferates while undergoing EMT. When contact inhibition of post-confluent ARPE-19 cells was disrupted by EGTA, an increase of BrdU labeling was noted only in the presence of EGF and/or FGF-2, and was accompanied by EMT as evidenced by the loss of a normal RPE phenotype (altered cytolocalization of RPE65, N-cadherin, ZO-1, and Na,K-ATPase) and the gain of a mesenchymal phenotype (increased expression of vimentin, S100A4, and α-smooth muscle actin). EMT with proliferation by EGTA+EGF+FGF-2 was accompanied by activation of canonical Wnt signaling (judged by the TCF/LEF promoter activity, increased nuclear levels of and interaction between β-catenin and LEF1 proteins, and the replication by overexpression of β-catenin), abolished by concomitant addition of XAV939, a Wnt inhibitor, but not associated with suppression of Hippo signaling (negative expression of nuclear TAZ or YAP and cytoplasmic p-TAZ or p-YAP). The causative role of Wnt signaling on EMT with proliferation was confirmed by overexpression of stable S33Y β-catenin with EGTA treatment. In addition, contact inhibition disrupted by EGTA in the presence of TGF-β1 also led to EMT, but suppressed proliferation and Wnt signaling. The Wnt signaling triggered by EGF+FGF-2 was sufficient and synergized with TGF-β1 in activating the Smad/ZEB1/2 signaling responsible for EMT. These findings establish a framework for further dissecting how RPE might partake in a number of proliferative vitreoretinopathies characterized by EMT.
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Affiliation(s)
- Hung-Chi Chen
- Tissue Tech, Inc., Ocular Surface Center, and Ocular Surface Research & Education Foundation, Miami, FL, USA,Department of Ophthalmology, Chang Gung Memorial Hospital and Graduate Institute of Clinical Medical Sciences, Chang Gung University, Taoyuan, Taiwan
| | - Ying-Ting Zhu
- Tissue Tech, Inc., Ocular Surface Center, and Ocular Surface Research & Education Foundation, Miami, FL, USA
| | - Szu-Yu Chen
- Tissue Tech, Inc., Ocular Surface Center, and Ocular Surface Research & Education Foundation, Miami, FL, USA
| | - Scheffer C. G. Tseng
- Tissue Tech, Inc., Ocular Surface Center, and Ocular Surface Research & Education Foundation, Miami, FL, USA
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1599
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Transcriptional regulation of aquaporin-3 in human retinal pigment epithelial cells. Mol Biol Rep 2012; 39:7949-56. [PMID: 22535323 DOI: 10.1007/s11033-012-1640-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Accepted: 04/16/2012] [Indexed: 12/30/2022]
Abstract
The expression of aquaporin (AQP) water channels may influence the development of retinal edema. We investigated the transcriptional regulation of AQP3 in cultured human retinal pigment epithelial (RPE) cells. As shown by RT-PCR and immunocytochemistry, cultured RPE cells express AQP3 mRNA and protein. The AQP3 mRNA level in RPE cells was elevated under the following conditions: chemical hypoxia induced by CoCl(2), hyperosmolarity induced by 100 mM NaCl, and upon stimulation of the cultures with PDGF, arachidonic acid, prostaglandin E(2), and blood serum, respectively. Chemical hypoxia increased AQP3 gene expression through MEK/ERK and JNK activation. The hyperosmolarity-, PDGF-, and serum-induced upregulation of AQP3 was prevented by inhibition of the phospholipase A(2), but not by inhibition of the cyclooxygenase. Triamcinolone acetonide prevented the upregulation of AQP3 induced by arachidonic acid and prostaglandin E(2), but not by the other factors tested. It is concluded that AQP3 is transcriptionally activated in RPE cells by various pathogenic factors involved in the development of retinal edema in situ. Activation of phospholipase A(2) is a critical factor which induces AQP3 in RPE cells.
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1600
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Abstract
PURPOSE OF REVIEW Various medications can modify the physiology of retinal and cochlear neurons and lead to major, sometime permanent, sensory loss. A better knowledge of pathogenic mechanisms and the establishment of relevant monitoring protocols are necessary to prevent permanent sensory impairment. In this article, we review main systemic medications associated with direct neuronal toxicity on the retina and cochlea, their putative pathogenic mechanisms, when identified, as well as current recommendations, when available, for monitoring protocols. RECENT FINDINGS Pathogenic mechanisms and cellular target of retinotoxic drugs are often not well characterized but a better knowledge of the course of visual defect has recently helped in defining more relevant monitoring protocols especially for antimalarials and vigabatrin. Mechanisms of ototoxicity have recently been better defined, from inner ear entry with the use of fluorescent tracers to evidence for the role of oxidative stress and program cell death pathways. SUMMARY Experimental and clinical studies have elucidated some of the pathogenic mechanisms, courses and risk factors of retinal toxicity and ototoxicity, which have led to establishment of relevant monitoring protocols. Further studies are, however, warranted to better understand cellular pathways leading to degeneration. These would help to build more efficient preventive intervention and may also contribute to understanding of other degenerative processes such as genetic disorders.
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