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Nakai-Futatsugi Y, Jin J, Ogawa T, Sakai N, Maeda A, Hironaka KI, Fukuda M, Danno H, Tanaka Y, Hori S, Shiroguchi K, Takahashi M. Pigmentation level of human iPSC-derived RPE does not indicate a specific gene expression profile. eLife 2024; 12:RP92510. [PMID: 38722314 PMCID: PMC11081631 DOI: 10.7554/elife.92510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2024] Open
Abstract
Retinal pigment epithelium (RPE) cells show heterogeneous levels of pigmentation when cultured in vitro. To know whether their color in appearance is correlated with the function of the RPE, we analyzed the color intensities of human-induced pluripotent stem cell-derived RPE cells (iPSC-RPE) together with the gene expression profile at the single-cell level. For this purpose, we utilized our recent invention, Automated Live imaging and cell Picking System (ALPS), which enabled photographing each cell before RNA-sequencing analysis to profile the gene expression of each cell. While our iPSC-RPE were categorized into four clusters by gene expression, the color intensity of iPSC-RPE did not project any specific gene expression profiles. We reasoned this by less correlation between the actual color and the gene expressions that directly define the level of pigmentation, from which we hypothesized the color of RPE cells may be a temporal condition not strongly indicating the functional characteristics of the RPE.
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Affiliation(s)
- Yoko Nakai-Futatsugi
- Laboratory for Retinal Regeneration, RIKEN Biosystems Dynamics Research (BDR)KobeJapan
- VC Cell Therapy IncKobeJapan
- Ritsumeikan UniversityShigaJapan
| | - Jianshi Jin
- Laboratory for Prediction of Cell Systems Dynamics, RIKEN Center for Biosystems Dynamics Research (BDR)SuitaJapan
| | - Taisaku Ogawa
- Laboratory for Prediction of Cell Systems Dynamics, RIKEN Center for Biosystems Dynamics Research (BDR)SuitaJapan
| | - Noriko Sakai
- Laboratory for Retinal Regeneration, RIKEN Biosystems Dynamics Research (BDR)KobeJapan
- VC Cell Therapy IncKobeJapan
| | - Akiko Maeda
- Laboratory for Retinal Regeneration, RIKEN Biosystems Dynamics Research (BDR)KobeJapan
- Ritsumeikan UniversityShigaJapan
- Kobe City Eye Hospital, Department of OphthalmologyKobeJapan
| | | | | | | | - Yuji Tanaka
- Laboratory for Retinal Regeneration, RIKEN Biosystems Dynamics Research (BDR)KobeJapan
| | | | - Katsuyuki Shiroguchi
- Laboratory for Prediction of Cell Systems Dynamics, RIKEN Center for Biosystems Dynamics Research (BDR)SuitaJapan
| | - Masayo Takahashi
- Laboratory for Retinal Regeneration, RIKEN Biosystems Dynamics Research (BDR)KobeJapan
- Ritsumeikan UniversityShigaJapan
- Kobe City Eye Hospital, Department of OphthalmologyKobeJapan
- Vision Care, IncKobeJapan
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Lee YW, Lim MN, Lee JY, Yoo YJ. Central retina thickness measured with spectral-domain optical coherence tomography in Parkinson disease: A meta-analysis. Medicine (Baltimore) 2023; 102:e35354. [PMID: 37800768 PMCID: PMC10553016 DOI: 10.1097/md.0000000000035354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 09/01/2023] [Indexed: 10/07/2023] Open
Abstract
BACKGROUND Optical coherence tomography (OCT) can detect visual alterations associated with Parkinson disease, such as damage to the retinal nerve fiber layer or changes in retinal vasculature. Macula thinning in association with Parkinson disease (PD) remains controversial. Therefore, we conducted a meta-analysis to investigate the central retina thickness in PD measured using spectral-domain OCT (SD-OCT). METHODS We searched PubMed and the Excerpta Medica database to identify studies that compared macular thickness between patients with PD and healthy controls published before July 31, 2021. A random-effects model was used to examine PD-associated changes in macular thickness. Meta-regression analysis was performed by assessing heterogeneity, publication bias, and study quality. RESULTS Thirty-two studies with a cross-sectional design were selected, including 2118 patients with PD and 2338 controls. We identified significant differences in the thickness of the ganglion cell-inner plexiform layer (standardized mean difference [SMD], -0.41; 95% confidence interval [CI], -0.66 to -0.16; I2 = 80%), ganglion cell complex (SMD, -0.33; 95% CI, -0.50 to -0.17; I2 = 0%), and of all inner and outer sectors of the macula (SMD range, -0.21 to -0.56; all P < .05) between patients with PD and controls. DISCUSSION These results corroborate the increased prevalence of changes in OCT measures in individuals with PD, highlighting the efficacy of SD-OCT-determined macular thickness as a biomarker for PD. Our findings may provide helpful guidelines for clinicians in rapidly evolving areas of PD diagnosis.
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Affiliation(s)
- Yong Woo Lee
- Department of Ophthalmology, Kangwon National University School of Medicine, Chuncheon, Korea
- Department of Ophthalmology, Kangwon National University Hospital, Chuncheon, Korea
| | - Myung-Nam Lim
- Biomedical Research Institute, Kangwon National University School of Medicine, Chuncheon, Korea
| | - Jae Yeon Lee
- Department of Ophthalmology, Kangwon National University School of Medicine, Chuncheon, Korea
| | - Yung-Ju Yoo
- Department of Ophthalmology, Kangwon National University School of Medicine, Chuncheon, Korea
- Department of Ophthalmology, Kangwon National University Hospital, Chuncheon, Korea
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3
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The First Homozygote Mutation c.499G>T (Asp167Tyr) in the RPE65 Gene Encoding Retinoid Isomerohydrolase Causing Retinal Dystrophy. Curr Issues Mol Biol 2022; 44:6397-6403. [PMID: 36547097 PMCID: PMC9777422 DOI: 10.3390/cimb44120436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 12/08/2022] [Accepted: 12/14/2022] [Indexed: 12/23/2022] Open
Abstract
RPE65, an abundant membrane-associated protein present in the retinal pigment epithelium (RPE), is a vital retinoid isomerase necessary for regenerating 11-cis-retinaldehyde from all-trans retinol in the visual cycle. In patients with inherited retinal dystrophy (IRD), precise genetic diagnosis is an indispensable approach as it is required to establish eligibility for the genetic treatment of RPE65-associated IRDs. This case report aims to report the specific phenotype−genotype correlation of the first patient with a homozygous missense variant RPE65 c.499G>T, p. (Asp167Tyr). We report a case of a 66-year-old male who demonstrated a unique phenotype manifesting less severe functional vision deterioration in childhood and adolescence, and extensive nummular pigment clusters. The underlying causes of the differences in the typical bone spicule and atypical nummular pigment clumping are unknown, but suggest that the variant itself influenced the rate of photoreceptor death. Functional studies are needed to define whether the substitution of aspartate impairs the folding of the tertiary RPE65 structure only and does not lead to the complete abolishment of chromophore production, thus explaining the less severe phenotype in adolescence.
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Kwon YS, Zheng M, Zhang AY, Han Z. Melanin-like Nanoparticles as an Alternative to Natural Melanin in Retinal Pigment Epithelium Cells and Their Therapeutic Effects against Age-Related Macular Degeneration. ACS NANO 2022; 16:19412-19422. [PMID: 36269679 DOI: 10.1021/acsnano.2c09087] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Melanin is a natural pigment that is widely distributed in many parts of the human body, such as the skin and retinal pigment epithelium (RPE) in eyes. In contrast to skin melanin, which is being constantly synthesized by the epidermal melanocytes, melanin in the RPE does not regenerate. Melanin is known to function as a potential radical scavenger and photoprotective agent. However, the protective effects of melanin against oxidative stress decline with increasing age. This phenomenon has been correlated with the pathogenesis of age-related macular degeneration (AMD). To increase the potential antioxidant and photoprotective characteristics of melanin, we designed a therapeutic strategy for replenishment of melanin using PEGylated synthetic melanin-like nanoparticles (MNPs) in the RPE for the treatment of AMD. We performed experiments using AMD-like cellular and mouse models and demonstrated that MNPs are biocompatible and selectively target reactive oxygen species (ROS) with powerful antioxidant properties. MNPs can traffic and accumulate in the RPE and are exclusively located in cytosol, but not the nucleus and mitochondria of the cells, for at least 3 months after a single-dose intravitreal injection. Our findings demonstrate that MNPs are able to substitute for natural melanin in the RPE and suggest the potential efficacy of MNPs as a natural radical scavenger against oxidative stress in ROS-related diseases, such as AMD.
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Affiliation(s)
- Yong-Su Kwon
- Department of Ophthalmology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina27599, United States
| | - Min Zheng
- Department of Ophthalmology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina27599, United States
| | - Alice Yang Zhang
- Department of Ophthalmology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina27599, United States
| | - Zongchao Han
- Department of Ophthalmology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina27599, United States
- Division of Pharmacoengineering & Molecular Pharmaceutics, Eshelman School of Pharmacy, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina27599, United States
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Dong EM, Allison WT. Vertebrate features revealed in the rudimentary eye of the Pacific hagfish ( Eptatretus stoutii). Proc Biol Sci 2021; 288:20202187. [PMID: 33434464 DOI: 10.1098/rspb.2020.2187] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Hagfish eyes are markedly basic compared to the eyes of other vertebrates, lacking a pigmented epithelium, a lens and a retinal architecture built of three cell layers: the photoreceptors, interneurons and ganglion cells. Concomitant with hagfish belonging to the earliest-branching vertebrate group (the jawless Agnathans), this lack of derived characters has prompted competing interpretations that hagfish eyes represent either a transitional form in the early evolution of vertebrate vision, or a regression from a previously elaborate organ. Here, we show the hagfish retina is not extensively degenerating during its ontogeny, but instead grows throughout life via a recognizable PAX6+ ciliary marginal zone. The retina has a distinct layer of photoreceptor cells that appear to homogeneously express a single opsin of the RH1 rod opsin class. The epithelium that encompasses these photoreceptors is striking because it lacks the melanin pigment that is universally associated with animal vision; notwithstanding, we suggest this epithelium is a homologue of gnathosome retinal pigment epithelium (RPE) based on its robust expression of RPE65 and its engulfment of photoreceptor outer segments. We infer that the hagfish retina is not entirely rudimentary in its wiring, despite lacking a morphologically distinct layer of interneurons: multiple populations of cells exist in the hagfish inner retina and subsets of these express markers of vertebrate retinal interneurons. Overall, these data clarify Agnathan retinal homologies, reveal characters that now appear to be ubiquitous across the eyes of vertebrates, and refine interpretations of early vertebrate visual system evolution.
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Affiliation(s)
- Emily M Dong
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T7Y 1C4
| | - W Ted Allison
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T7Y 1C4
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6
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Yacout SM, Elsawa SF, Gaillard ER. Calf melanin immunomodulates RPE cell attachment to extracellular matrix protein. Graefes Arch Clin Exp Ophthalmol 2018; 256:1883-1893. [PMID: 30066027 DOI: 10.1007/s00417-018-4083-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Revised: 07/23/2018] [Accepted: 07/26/2018] [Indexed: 10/28/2022] Open
Abstract
PURPOSE It is widely accepted that RPE melanin has a protective effect against oxidative damage in RPE cells. It is possible that an additional protective characteristic of melanin is the ability to modulate RPE cell immune response. In this study, in vitro modeling was used to probe the relationship between RPE pigmentation and immune response by monitoring IL-6 expression and secretion in calf melanin pigmented ARPE-19 cells seeded onto glycated extracellular matrix as a stressor. METHODS ARPE-19 cells were left unpigmented or were pigmented with either calf melanin or latex beads, and were then seeded onto RPE-derived extracellular matrix (ECM) or tissue culture-treated plates (no ECM). ECMs were modified by glycation. IL-6 expression was measured using qPCR and IL-6 secretion was determined using an ELISA, both at 30 min and 24 h after seeding. MTT assay was used to quantify cell attachment to glycated matrices 30 min after seeding. In unpigmented ARPE-19 cells, rate of cell attachment to substrate was monitored for 60 min after seeding using a hemacytometer to count unattached cells. Additionally, cell viability was evaluated using the Neutral Red assay 24 h after seeding. RESULTS A significant increase in IL-6 expression was observed in calf melanin pigmented cells versus latex bead and unpigmented controls (p < 0.0001) 30 min after seeding onto ECM. Twenty-four hours after seeding, a significant decrease in IL-6 expression was observed in calf melanin pigmented cells (p < 0.0001) versus controls, implicating down-regulation of the cytokine. Additionally, calf melanin pigmented cell populations showed significant increase in attachment compared to unpigmented controls on either no ECM or unmodified ECM. CONCLUSIONS Pigmentation of RPE cells with calf melanin resulted in significant changes in IL-6 expression regardless of ECM modification, in vitro. These findings suggest that melanin in the RPE may participate in immune response modulation in the retina with particular regard to cell attachment to protein substrates. The results of this study further implicate the role of chemical changes to melanin in regulating inflammation in retinal disease.
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Affiliation(s)
- Sally M Yacout
- Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, IL, 60115, USA
| | - Sherine F Elsawa
- Department of Biological Sciences, Northern Illinois University, DeKalb, IL, 60115, USA
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, 03824, USA
| | - Elizabeth R Gaillard
- Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, IL, 60115, USA.
- Department of Biological Sciences, Northern Illinois University, DeKalb, IL, 60115, USA.
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Pardue MT, Allen RS. Neuroprotective strategies for retinal disease. Prog Retin Eye Res 2018; 65:50-76. [PMID: 29481975 PMCID: PMC6081194 DOI: 10.1016/j.preteyeres.2018.02.002] [Citation(s) in RCA: 141] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 02/14/2018] [Accepted: 02/20/2018] [Indexed: 12/20/2022]
Abstract
Diseases that affect the eye, including photoreceptor degeneration, diabetic retinopathy, and glaucoma, affect 11.8 million people in the US, resulting in vision loss and blindness. Loss of sight affects patient quality of life and puts an economic burden both on individuals and the greater healthcare system. Despite the urgent need for treatments, few effective options currently exist in the clinic. Here, we review research on promising neuroprotective strategies that promote neuronal survival with the potential to protect against vision loss and retinal cell death. Due to the large number of neuroprotective strategies, we restricted our review to approaches that we had direct experience with in the laboratory. We focus on drugs that target survival pathways, including bile acids like UDCA and TUDCA, steroid hormones like progesterone, therapies that target retinal dopamine, and neurotrophic factors. In addition, we review rehabilitative methods that increase endogenous repair mechanisms, including exercise and electrical stimulation therapies. For each approach, we provide background on the neuroprotective strategy, including history of use in other diseases; describe potential mechanisms of action; review the body of research performed in the retina thus far, both in animals and in humans; and discuss considerations when translating each treatment to the clinic and to the retina, including which therapies show the most promise for each retinal disease. Despite the high incidence of retinal diseases and the complexity of mechanisms involved, several promising neuroprotective treatments provide hope to prevent blindness. We discuss attractive candidates here with the goal of furthering retinal research in critical areas to rapidly translate neuroprotective strategies into the clinic.
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Affiliation(s)
- Machelle T Pardue
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Medical Center, 1670 Clairmont Road, Decatur, GA, 30033, USA; Department of Biomedical Engineering, Georgia Institute of Technology, 313 Ferst Drive, Atlanta, GA, 30332, USA.
| | - Rachael S Allen
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Medical Center, 1670 Clairmont Road, Decatur, GA, 30033, USA
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8
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Patrício MI, Barnard AR, Xue K, MacLaren RE. Choroideremia: molecular mechanisms and development of AAV gene therapy. Expert Opin Biol Ther 2018; 18:807-820. [DOI: 10.1080/14712598.2018.1484448] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Maria I Patrício
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
- National Institute for Health Research (NIHR) Oxford Biomedical Research Centre (BRC), Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Alun R Barnard
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
- National Institute for Health Research (NIHR) Oxford Biomedical Research Centre (BRC), Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Kanmin Xue
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
- National Institute for Health Research (NIHR) Oxford Biomedical Research Centre (BRC), Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Robert E MacLaren
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
- National Institute for Health Research (NIHR) Oxford Biomedical Research Centre (BRC), Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
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Bonilha VL, Bell BA, Rayborn ME, Samuels IS, King A, Hollyfield JG, Xie C, Cai H. Absence of DJ-1 causes age-related retinal abnormalities in association with increased oxidative stress. Free Radic Biol Med 2017; 104:226-237. [PMID: 28088625 PMCID: PMC5328840 DOI: 10.1016/j.freeradbiomed.2017.01.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 01/09/2017] [Accepted: 01/10/2017] [Indexed: 01/05/2023]
Abstract
Oxidative stress alters physiological function in most biological tissues and can lead to cell death. In the retina, oxidative stress initiates a cascade of events leading to focal loss of RPE and photoreceptors, which is thought to be a major contributing factor to geographic atrophy. Despite these implications, the molecular regulation of RPE oxidative stress under normal and pathological conditions remains largely unknown. A better understanding of the mechanisms involved in regulating RPE and photoreceptors oxidative stress response is greatly needed. To this end we evaluated photoreceptor and RPE changes in mice deficient in DJ-1, a protein that is thought to be important in protecting cells from oxidative stress. Young (3 months) and aged (18 months) DJ-1 knockout (DJ-1 KO) and age-matched wild-type mice were examined. In both group of aged mice, scanning laser ophthalmoscopy (SLO) showed the presence of a few autofluorescent foci. The 18 month-old DJ-1 KO retinas were also characterized by a noticeable increase in RPE fluorescence to wild-type. Optical coherence tomography (OCT) imaging demonstrated that all retinal layers were present in the eyes of both DJ-1 KO groups. ERG comparisons showed that older DJ-1 KO mice had reduced sensitivity under dark- and light-adapted conditions compared to age-matched control. Histologically, the RPE contained prominent vacuoles in young DJ-1 KO group with the appearance of enlarged irregularly shaped RPE cells in the older group. These were also evident in OCT and in whole mount RPE/choroid preparations labeled with phalloidin. Photoreceptors in the older DJ-1 KO mice displayed decreased immunoreactivity to rhodopsin and localized reduction in cone markers compared to the wild-type control group. Lower levels of activated Nrf2 were evident in retina/RPE lysates in both young and old DJ-1 KO mouse groups compared to wild-type control levels. Conversely, higher levels of protein carbonyl derivatives and iNOS immunoreactivity were detected in retina/RPE lysates from both young and old DJ-1 KO mice. These results demonstrate that DJ-1 KO mice display progressive signs of retinal/RPE degeneration in association with higher levels of oxidative stress markers. Collectively this analysis indicates that DJ-1 plays an important role in protecting photoreceptors and RPE from oxidative damage during aging.
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Affiliation(s)
- Vera L Bonilha
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine at Case Western Reserve University, Cleveland, OH 44195, USA; Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
| | - Brent A Bell
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Mary E Rayborn
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Ivy S Samuels
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA; Research Service, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH 44106, USA
| | - Anna King
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Joe G Hollyfield
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine at Case Western Reserve University, Cleveland, OH 44195, USA; Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Chengsong Xie
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, MD, USA
| | - Huaibin Cai
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, MD, USA
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Abstract
PURPOSE To test the diagnostic ability of spectral domain optical coherence tomography for the detection of Parkinson disease using retinal nerve fiber layer and retinal thickness parameters. Retinal pigment epithelium produces levodopa. METHODS Patients with Parkinson disease (n = 111) and healthy subjects (n = 200) were enrolled. The Spectralis optical coherence tomography was used to obtain retinal nerve fiber layer thickness and retinal measurements. Two linear discriminant functions (LDFs) were developed, one using retinal nerve fiber layer parameters and another using retinal thickness. A validating set was used to test the performance of both LDFs. Receiver operating characteristic curves were plotted and compared with the standard parameters provided by optical coherence tomography for both LDFs. Sensitivity and specificity were used to evaluate diagnostic performance. RESULTS The Retinal LDF combines only retinal thickness parameters and provided the best performance: 31.173 + 0.026 × temporal outer - 0.267 × superior outer + 0.159 × nasal outer - 0.197 × inferior outer - 0.060 × superior inner + 0.049 × foveal thickness. The largest areas under the receiver operating characteristic curve were 0.902 for Retinal LDF. The Retinal LDF yielded the highest sensitivity values. CONCLUSION Measurements of retinal thickness differentiate between subjects who are healthy and those with advanced Parkinson disease.
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Boulton ME. Studying melanin and lipofuscin in RPE cell culture models. Exp Eye Res 2014; 126:61-7. [PMID: 25152361 DOI: 10.1016/j.exer.2014.01.016] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2013] [Revised: 01/18/2014] [Accepted: 01/20/2014] [Indexed: 01/05/2023]
Abstract
The retinal pigment epithelium contains three major types of pigment granules; melanosomes, lipofuscin and melanolipofuscin. Melanosomes in the retinal pigment epithelium (RPE) are formed during embryogenesis and mature during early postnatal life while lipofuscin and melanolipofuscin granules accumulate as a function of age. The difficulty in studying the formation and consequences of melanosomes and lipofuscin granules in RPE cell culture is compounded by the fact that these pigment granules do not normally occur in established RPE cell lines and pigment granules are rapidly lost in adult human primary culture. This review will consider options available for overcoming these limitations and permitting the study of melanosomes and lipofuscin in cell culture and will briefly evaluate the advantages and disadvantages of the different protocols.
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Affiliation(s)
- Michael E Boulton
- Department of Ophthalmology, Indiana University School of Medicine, USA.
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Bu L, Li R, Liu H, Feng W, Xiong X, Zhao H, Vollrath D, Shen B, Cheng Z. Intrastriatal transplantation of retinal pigment epithelial cells for the treatment of Parkinson disease: in vivo longitudinal molecular imaging with 18F-P3BZA PET/CT. Radiology 2014; 272:174-83. [PMID: 24758555 DOI: 10.1148/radiol.14132042] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To evaluate the performance of N-[2-(diethylamino)ethyl]-(18)F-5-fluoropicolinamide ((18)F-P3BZA) for visualizing porcine retinal pigment epithelium (pRPE) cells transplanted in the striatum for the treatment of Parkinson disease and to monitor the long-term activity of implanted pRPE cells by means of (18)F-P3BZA positron emission tomography (PET)/computed tomography (CT) in vivo. MATERIALS AND METHODS Animal work was conducted in accordance with the administrative panel on laboratory animal care. In vitro cell uptake of (18)F-P3BZA was determined with incubation of melanotic pRPE or amelanotic ARPE-19 cells with (18)F-P3BZA. To visualize the implanted pRPE cells in vivo, normal rats (four per group) were injected with pRPE or ARPE-19 cells attached to gelatin microcarriers in the left striatum and with control gelatin microcarriers in the right striatum and followed up with small animal PET/CT. Longitudinal PET/CT scans were acquired in 12 rats up to 16 days after surgery. Postmortem analysis, which included autoradiography and hematoxylin-eosin, Fontana-Masson, and immunofluorescence staining, was performed. Data were compared with the Student t test, analysis of variance, and regression analysis. RESULTS (18)F-P3BZA accumulated in pRPE cells effectively (3.48% of the injected dose [ID] per gram of brain tissue ± 0.58 at 1 hour after injection of the probe at 2 days after surgery in vivo) but not in control ARPE-19 cells (P < .05). Longitudinal PET/CT scans revealed that the activity of implanted pRPE cells decreased over time, as evidenced by a reduction in (18)F-P3BZA uptake (3.39% ID/g ± 0.18, 2.49% ID/g ± 0.41, and 1.20% ID/g ± 0.13 at days 2, 9, and 16, respectively; P < .05). Postmortem analysis helped confirm the results of in vivo imaging. CONCLUSION (18)F-P3BZA PET/CT is a feasible technique for visualizing and detecting the activity of implanted RPE cells in vivo.
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Affiliation(s)
- Lihong Bu
- From the Molecular Imaging Program at Stanford (MIPS), Department of Radiology and Bio-X Program, Stanford University, 1201 Welch Rd, Lucas Center, Room P095, Stanford, CA 94305-5484 (L.B., R.L., H.L., Z.C.); Molecular Imaging Center, Department of Radiology, The 4th Hospital of Harbin Medical University, Harbin, Heilongjiang, P.R. China (L.B., R.L., B.S.); and Departments of Genetics (W.F., D.V.) and Neurosurgery (X.X., H.Z.), School of Medicine, Stanford University, Stanford, Calif
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Choi B, Heo JH, Kwon HJ, Lee ES, Sohn S. Tocotrienols enhance melanosome degradation through endosome docking/fusion proteins in B16F10 melanoma cells. Food Funct 2014; 4:1481-8. [PMID: 23995710 DOI: 10.1039/c3fo60289c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Vitamin E inhibits tyrosinase activity and acts as a melanogenesis inhibitor in epidermal melanocytes in vitro. However, there is no direct evidence indicating that melanosomes are degraded in lysosomes in the presence of vitamin E. To determine whether vitamin E-induced melanosome disintegration is related to the expression of endosome docking/fusion proteins in B16F10 melanoma cells, electron microscopy, reverse transcription-polymerase chain reaction (RT-PCR), and real-time PCR were used to observe the effects of tocomin (α-tocopherols and α,γ,δ-tocotrienols in palm oil) on B16F10 melanoma cells. Melanosomal integrity was lost in lysosomes of B16F10 melanoma cells when treated with tocomin, indicating that tocomin caused the degradation of melanosomes in the lysosomal compartment. RT-PCR and real-time PCR analysis demonstrated mRNA expression of tyrosinase and the endosome docking/fusion proteins (syntaxin7, Rab7, Vps11, Vps16, Vps33, Vps39, and Vps41). Expression of syntaxin7, Vps16, Vps33, and Vps41 mRNA increased significantly in cells treated with tocomin compared with that in controls. These results indicate that the tocomin-induced degradation of melanosomes in the lysosomal compartment occurs with an increase in endosome docking/fusion proteins (syntaxin7, Vps16, Vps33, and Vps41) in cultured B16F10 melanoma cells.
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Affiliation(s)
- Bunsoon Choi
- Laboratory of Cell Biology, Ajou University Institute for Medical Sciences, Suwon 443-721, South Korea.
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Garcia-Martin E, Larrosa JM, Polo V, Satue M, Marques ML, Alarcia R, Seral M, Fuertes I, Otin S, Pablo LE. Distribution of retinal layer atrophy in patients with Parkinson disease and association with disease severity and duration. Am J Ophthalmol 2014; 157:470-478.e2. [PMID: 24315296 DOI: 10.1016/j.ajo.2013.09.028] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 09/28/2013] [Accepted: 09/30/2013] [Indexed: 11/26/2022]
Abstract
PURPOSE To evaluate the thickness of the 10 retinal layers in the paramacular area of Parkinson disease patients using a new segmentation technology of optical coherence tomography (OCT) to examine whether the thickness of specific layers predicts neurodegeneration or Parkinson disease severity. DESIGN Observational prospective study. METHODS Parkinson disease patients (n = 129) and age-matched healthy subjects (n = 129) were enrolled. The Spectralis OCT system was used to automatically segment all retinal layers in a parafoveal scan using the new segmentation application prototype. Mean thickness of each layer was calculated and compared between Parkinson disease patients and healthy subjects, and between Parkinson disease patients with disease durations of less than or at least 10 years. A correlation analysis was performed to evaluate the association between retinal layer thickness, duration of disease, and Parkinson disease severity. Logistic regression analysis was performed to determine the most sensitive layer for predicting axonal atrophy. RESULTS Parkinson disease patients showed statistically significant reduced thickness in the retinal nerve fiber, ganglion cell, inner plexiform, and outer plexiform layers and increased thickness in the inner nuclear layer compared with healthy subjects (P < .05). The inner retinal layers were more affected in Parkinson disease patients with long disease duration. The ganglion cell layer thickness was inversely correlated with disease duration and Parkinson disease severity, and was predictive of axonal damage in Parkinson disease patients. CONCLUSIONS The segmentation application of the Spectralis OCT revealed retinal layer atrophy in Parkinson disease patients, especially in the inner layers of patients with long disease duration. Ganglion cell layer reduction was associated with increased axonal damage.
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Sorkio A, Hongisto H, Kaarniranta K, Uusitalo H, Juuti-Uusitalo K, Skottman H. Structure and barrier properties of human embryonic stem cell-derived retinal pigment epithelial cells are affected by extracellular matrix protein coating. Tissue Eng Part A 2014; 20:622-34. [PMID: 24044751 DOI: 10.1089/ten.tea.2013.0049] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Extracellular matrix (ECM) interactions play a vital role in cell morphology, migration, proliferation, and differentiation of cells. We investigated the role of ECM proteins on the structure and function of human embryonic stem cell-derived retinal pigment epithelial (hESC-RPE) cells during their differentiation and maturation from hESCs into RPE cells in adherent differentiation cultures on several human ECM proteins found in native human Bruch's membrane, namely, collagen I, collagen IV, laminin, fibronectin, and vitronectin, as well as on commercial substrates of xeno-free CELLstart™ and Matrigel™. Cell pigmentation, expression of RPE-specific proteins, fine structure, as well as the production of basal lamina by hESC-RPE on different protein coatings were evaluated after 140 days of differentiation. The integrity of hESC-RPE epithelium and barrier properties on different coatings were investigated by measuring transepithelial resistance. All coatings supported the differentiation of hESC-RPE cells as demonstrated by early onset of cell pigmentation and further maturation to RPE monolayers after enrichment. Mature RPE phenotype was verified by RPE-specific gene and protein expression, correct epithelial polarization, and phagocytic activity. Significant differences were found in the degree of RPE cell pigmentation and tightness of epithelial barrier between different coatings. Further, the thickness of self-assembled basal lamina and secretion of the key ECM proteins found in the basement membrane of the native RPE varied between hESC-RPE cultured on compared protein coatings. In conclusion, this study shows that the cell culture substrate has a major effect on the structure and basal lamina production during the differentiation and maturation of hESC-RPE potentially influencing the success of cell integrations and survival after cell transplantation.
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Affiliation(s)
- Anni Sorkio
- 1 Institute of Biomedical Technology, University of Tampere , Tampere, Finland
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16
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Klotho regulates retinal pigment epithelial functions and protects against oxidative stress. J Neurosci 2013; 33:16346-59. [PMID: 24107965 DOI: 10.1523/jneurosci.0402-13.2013] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The retinal pigment epithelium (RPE) is a highly specialized CNS tissue that plays crucial roles in retinal homeostasis. Age-related morphological changes in the RPE have been associated with retinal degenerative disorders; our understanding of the underlying molecular mechanisms, however, remains incomplete. Here we report on a key role of Klotho (Kl), an aging-suppressor gene, in retinal health and RPE physiology. Kl(-/-) mice show RPE and photoreceptor degeneration, reduced pigment synthesis in the RPE, and impaired phagocytosis of the outer segment of the photoreceptors. Klotho protein (KL) is expressed in primary cultured human RPE, and regulates pigment synthesis by increasing the expression of MITF (microphthalmia transcription factor) and TYR (tyrosinase), two pivotal genes in melanogenesis. Importantly, KL increases phagocytosis in cultured RPE by inducing gene expression of MERTK/AXL/TYRO3. These effects of KL are mediated through cAMP-PKA-dependent phosphorylation of transcription factor CREB. In cultured human RPE, KL increases the l-3,4-dihydroxyphenylalanine synthesis and inhibits vascular endothelial growth factor (VEGF) secretion from basal membrane by inhibiting IGF-1 signaling and VEGF receptor 2 phosphorylation. KL also regulates the expression of stress-related genes in RPE, lowers the production of reactive oxygen species, and thereby, protects RPE from oxidative stress. Together, our results demonstrate a critical function for KL in mouse retinal health in vivo, and a protective role toward human RPE cells in vitro. We conclude that KL is an important regulator of RPE homeostasis, and propose that an age-dependent decline of KL expression may contribute to RPE degeneration and retinal pathology.
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17
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Efficacy and safety of computer-assisted stereotactic transplantation of human retinal pigment epithelium cells in the treatment of Parkinson disease. J Comput Assist Tomogr 2013; 37:333-7. [PMID: 23674001 DOI: 10.1097/rct.0b013e318287367f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE This study explores the efficacy and safety of computer-assisted stereotactic transplantation of human retinal pigment epithelium (hRPE) cells in the treatment of Parkinson disease (PD). METHODS Guided by computed tomography and magnetic resonance imaging image mergence, we transplanted 4 × 10 hRPE cells into the putamina and lateral ventricles of 17 PD cases by stereotactic surgery. The transplantation site was located in the contralateral side of the symptoms and signs. RESULTS At 3 months after operation, the effective rates of cell transplantation were 82.4% in the contralateral site and 64.7% in the ipsilateral site. Minority of the cases had mild dizziness and hemiparesis, but the durations were short. CONCLUSIONS Computer-assisted stereotactic transplantation of hRPE for the treatment of PD is safe and efficient.
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18
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Yin F, Tian ZM, Liu S, Zhao QJ, Wang RM, Shen L, Wieman J, Yan Y. Transplantation of human retinal pigment epithelium cells in the treatment for Parkinson disease. CNS Neurosci Ther 2013. [PMID: 23190934 DOI: 10.1111/cns.12025] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND AND PURPOSE To assess the clinical effect of transplantation of human retinal pigment epithelial (hRPE) cells into the unilateral postcommissural putamen for treatment for Parkinson disease (PD). METHODS AND RESULTS Cells from postmortem human eye tissue (10-20 weeks of gestation) were cultured in vitro. Cells from -generation passage were implanted in PD postcommissural putamen with stereotactic operation in 12 patients with PD. All patients tolerated surgery well, and no major adverse events occurred. Eleven patients showed improvement in the primary outcome measure at 3 months post-treatment, particularly the Unified Parkinson's Disease Rating Scale-M score in the off state. Response reached a peak at 12 months and declined during the next 24 months. At the 36-month endpoint, there were eight patients who felt better than at baseline. Positron emission tomography (PET) showed a trend with increased dopamine (DA) release during the first 6 months. CONCLUSION Human retinal pigment epithelial cells have the characteristics of neural progenitor cells and can be induced to differentiate into DA neurons. The results of this clinical trial suggest that the treatment of transplanted hRPE cells could improve symptoms of PD. These cells might serve as a useful source of DA neurons for neural graft in the treatment for PD.
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Affiliation(s)
- Feng Yin
- Institute of Neurosurgery, The PLA Navy General Hospital, Beijing, China
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19
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Phillips JC, Lembcke LM, Noltenius CE, Newman SJ, Blackford JT, Grosenbaugh DA, Leard AT. Evaluation of tyrosinase expression in canine and equine melanocytic tumors. Am J Vet Res 2012; 73:272-8. [DOI: 10.2460/ajvr.73.2.272] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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20
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Aydin IT, Hummler E, Smit NPM, Beermann F. Coat color dilution in mice because of inactivation of the melanoma antigen MART-1. Pigment Cell Melanoma Res 2011; 25:37-46. [PMID: 21943097 DOI: 10.1111/j.1755-148x.2011.00910.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Melanoma antigen recognized by T cells 1 (MART-1) is a melanoma-specific antigen, which has been thoroughly studied in the context of immunotherapy against malignant melanoma and which is found only in the pigment cell lineage. However, its exact function and involvement in pigmentation is not clearly understood. Melanoma antigen recognized by T cells 1 has been shown to interact with the melanosomal proteins Pmel17 and OA1. To understand the function of MART-1 in pigmentation, we developed a new knockout mouse model. Mice deficient in MART-1 are viable, but loss of MART-1 leads to a coat color phenotype, with a reduction in total melanin content of the skin and hair. Lack of MART-1 did not affect localization of melanocyte-specific proteins nor maturation of Pmel17. Melanosomes of hair follicle melanocytes in MART-1 knockout mice displayed morphological abnormalities, which were exclusive to stage III and IV melanosomes. In conclusion, our results suggest that MART-1 is a pigmentation gene that is required for melanosome biogenesis and/or maintenance.
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Affiliation(s)
- Iraz T Aydin
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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Intrastriatal transplantation of microcarrier-bound human retinal pigment epithelial cells versus sham surgery in patients with advanced Parkinson's disease: a double-blind, randomised, controlled trial. Lancet Neurol 2011; 10:509-19. [PMID: 21565557 DOI: 10.1016/s1474-4422(11)70097-7] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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22
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Lee HS, Cho HJ, Lee KW, Park SS, Seo HC, Suh HJ. Antioxidant Activities and Melanogenesis Inhibitory Effects of Terminalia chebula in B16/F10 Melanoma Cells. Prev Nutr Food Sci 2010. [DOI: 10.3746/jfn.2010.15.3.213] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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23
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Biesemeier A, Kreppel F, Kochanek S, Schraermeyer U. The classical pathway of melanogenesis is not essential for melanin synthesis in the adult retinal pigment epithelium. Cell Tissue Res 2010; 339:551-60. [PMID: 20140456 DOI: 10.1007/s00441-009-0920-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2009] [Accepted: 12/15/2009] [Indexed: 11/29/2022]
Abstract
Premelanosomes are presumed to be essential for melanogenesis in melanocytes and pre-natal retinal pigment epithelium (RPE) cells. We analysed melanin synthesis in adenoviral-transduced tyrosinase-gene-expressing amelanotic RPE (ARPE) 19 cells to determine whether premelanosome formation is needed for post-natal melanogenesis. The synthesis of melanogenic proteins and melanin granules was investigated by immunocytochemistry and light and electron microscopy. The occurrence of tyrosinase was analysed ultrastructurally by dihydroxyphenylalanine histochemistry. The viability of transduced cell cultures was examined via MTT assay. We found active tyrosinase in small granule-like vesicles throughout the cytoplasm and in the endoplasmic reticulum and nuclear membrane. Tyrosinase was also associated with multi-vesicular and multi-lamellar organelles. Typical premelanosomes, structural protein PMEL17, tyrosinase-related protein 1 and classic melanosomal stages I-IV were not detected. Instead, melanogenesis took place inside multi-vesicular and multi-lamellar bodies of unknown origin. Viability was not affected up to 10 days after transduction. We thus demonstrate a pathway of melanin formation lacking typical hallmarks of melanogenesis.
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Affiliation(s)
- Antje Biesemeier
- Department for Experimental Vitreoretinal Surgery, University Eye Hospital Tübingen, Germany.
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Ming M, Li X, Fan X, Yang D, Li L, Chen S, Gu Q, Le W. Retinal pigment epithelial cells secrete neurotrophic factors and synthesize dopamine: possible contribution to therapeutic effects of RPE cell transplantation in Parkinson's disease. J Transl Med 2009; 7:53. [PMID: 19558709 PMCID: PMC2709608 DOI: 10.1186/1479-5876-7-53] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Accepted: 06/28/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND New strategies for the treatment of Parkinson's disease (PD) are shifted from dopamine (DA) replacement to regeneration or restoration of the nigro-striatal system. A cell therapy using human retinal pigment epithelial (RPE) cells as substitution for degenerated dopaminergic (DAergic) neurons has been developed and showed promising prospect in clinical treatment of PD, but the exact mechanism underlying this therapy is not fully elucidated. In the present study, we investigated whether the beneficial effects of this therapy are related to the trophic properties of RPE cells and their ability to synthesize DA. METHODS We evaluated the protective effects of conditioned medium (CM) from cultured RPE cells on the DAergic cells against 6-hydroxydopamine (6-OHDA)- and rotenone-induced neurotoxicity and determined the levels of glial cell derived neurotrophic factor (GDNF) and brain derived neurotrophic factor (BDNF) released by RPE cells. We also measured the DA synthesis and release. Finally we transplanted microcarriers-RPE cells into 6-OHDA lesioned rats and observed the improvement in apomorphine-induced rotations (AIR). RESULTS We report here: (1) CM from RPE cells can secret trophic factors GDNF and BDNF, and protect DAergic neurons against the 6-OHDA- and rotenone-induced cell injury; (2) cultured RPE cells express L-dopa decarboxylase (DDC) and synthesize DA; (3) RPE cells attached to microcarriers can survive in the host striatum and improve the AIR in 6-OHDA-lesioned animal model of PD; (4) GDNF and BDNF levels are found significantly higher in the RPE cell-grafted tissues. CONCLUSION These findings indicate the RPE cells have the ability to secret GDNF and BDNF, and synthesize DA, which probably contribute to the therapeutic effects of RPE cell transplantation in PD.
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Affiliation(s)
- Ming Ming
- Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, and Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, PR China.
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AAV-mediated tyrosinase gene transfer restores melanogenesis and retinal function in a model of oculo-cutaneous albinism type I (OCA1). Mol Ther 2009; 17:1347-54. [PMID: 19436266 DOI: 10.1038/mt.2009.112] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Oculo-cutaneous albinism type 1 (OCA1) is characterized by congenital hypopigmentation and is due to mutations in the TYROSINASE gene (TYR). In this study, we have characterized the morpho-functional consequences of the lack of tyrosinase activity in the spontaneous null mouse model of OCA1 (Tyr(c-2j)). Here, we show that adult Tyr(c-2j) mice have several retinal functional anomalies associated with photoreceptor loss. To test whether these anomalies are reversible upon TYR complementation, we performed intraocular administration of an adeno-associated virus (AAV)-based vector, encoding the human TYR gene, in adult Tyr(c-2j) mice. This resulted in melanosome biogenesis and ex novo synthesis of melanin in both neuroectodermally derived retinal pigment epithelium (RPE) and in neural crest-derived choroid and iris melanocytes. Ocular melanin accumulation prevented progressive photoreceptor degeneration and resulted in restoration of retinal function. Our results reveal novel properties of pigment cells and show that the developmental anomalies of albino mice are associated with defects occurring in postnatal life, adding novel insights on OCA1 disease pathogenesis. In addition, we provide proof-of-principle of an effective gene-based strategy relevant for future application in albino patients.
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Lopes VS, Wasmeier C, Seabra MC, Futter CE. Melanosome maturation defect in Rab38-deficient retinal pigment epithelium results in instability of immature melanosomes during transient melanogenesis. Mol Biol Cell 2007; 18:3914-27. [PMID: 17671165 PMCID: PMC1995718 DOI: 10.1091/mbc.e07-03-0268] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Pathways of melanosome biogenesis in retinal pigment epithelial (RPE) cells have received less attention than those of skin melanocytes. Although the bulk of melanin synthesis in RPE cells occurs embryonically, it is not clear whether adult RPE cells continue to produce melanosomes. Here, we show that progression from pmel17-positive premelanosomes to tyrosinase-positive mature melanosomes in the RPE is largely complete before birth. Loss of functional Rab38 in the "chocolate" (cht) mouse causes dramatically reduced numbers of melanosomes in adult RPE, in contrast to the mild phenotype previously shown in skin melanocytes. Choroidal melanocytes in cht mice also have reduced melanosome numbers, but a continuing low level of melanosome biogenesis gradually overcomes the defect, unlike in the RPE. Partial compensation by Rab32 that occurs in skin melanocytes is less effective in the RPE, presumably because of the short time window for melanosome biogenesis. In cht RPE, premelanosomes form but delivery of tyrosinase is impaired. Premelanosomes that fail to deposit melanin are unstable in both cht and tyrosinase-deficient RPE. Together with the high levels of cathepsin D in immature melanosomes of the RPE, our results suggest that melanin deposition may protect the maturing melanosome from the activity of lumenal acid hydrolases.
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Affiliation(s)
- Vanda S. Lopes
- *Molecular and Cellular Medicine, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London SW7 2AZ, United Kingdom; and
| | - Christina Wasmeier
- *Molecular and Cellular Medicine, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London SW7 2AZ, United Kingdom; and
| | - Miguel C. Seabra
- *Molecular and Cellular Medicine, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London SW7 2AZ, United Kingdom; and
| | - Clare E. Futter
- Institute of Ophthalmology, University College London, London EC1V 9EL, United Kingdom
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Julien S, Kociok N, Kreppel F, Kopitz J, Kochanek S, Biesemeier A, Blitgen-Heinecke P, Heiduschka P, Schraermeyer U. Tyrosinase biosynthesis and trafficking in adult human retinal pigment epithelial cells. Graefes Arch Clin Exp Ophthalmol 2007; 245:1495-505. [PMID: 17318568 DOI: 10.1007/s00417-007-0543-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2006] [Revised: 01/15/2007] [Accepted: 01/21/2007] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Tyrosinase (EC 1.14.18.1) is the key enzyme of melanin pigment formation and it is unclear whether it is synthesized in human postnatal retinal pigment epithelium (RPE). In this study, we investigated if phagocytosis of rod outer segments (ROS) can increase tyrosinase expression in vitro. METHODS Primary cultures of human RPE cells were fed with isolated ROS from cattle and with latex particles. After phagocytosis, RPE cells were tested for tyrosinase presence and activity with several independent methods: (1) immunocytochemistry with anti-tyrosinase antibodies and (2) ultrastructural as well as light microscopic DOPA histochemistry; (3) mRNA was isolated from human RPE before incubation with ROS and 5, 20 and 40 h after feeding with ROS. The amount of tyrosinase mRNA was determined quantitatively by real-time reverse transcription polymerase chain reaction (RT-PCR), and the tyrosinase activity was investigated by measuring tyrosine hydroxylase activity using [(3)H]tyrosine. RESULTS Tyrosinase was found in fed RPE cells using these methods, but was absent without feeding. Furthermore, we showed co-localization of rhodopsin and tyrosinase in the fed RPE cells. Contrary to tyrosinase activity, the mRNA for tyrosinase was clearly present in the cultured RPE cells which had not been exposed to ROS, decreased significantly from 5 h after exposure to ROS and returned to its original non-fed level 40 h after ROS feeding. CONCLUSION Our study does not present new evidence that de novo melanogenesis takes place in the adult differentiated RPE. However, in contrast to the classic hypothesis, which states that tyrosinase is only detected in embryos, we provide evidence with several independent methods that the expression of tyrosinase and its enzymatic activity are induced in cultured human adult RPE by phagocytosis of ROS.
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Affiliation(s)
- Sylvie Julien
- Section for Experimental Vitreoretinal Surgery, University Eye Hospital Tuebingen, Tuebingen, Germany.
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