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Jones MK, Lu B, Girman S, Wang S. Cell-based therapeutic strategies for replacement and preservation in retinal degenerative diseases. Prog Retin Eye Res 2017; 58:1-27. [PMID: 28111323 PMCID: PMC5441967 DOI: 10.1016/j.preteyeres.2017.01.004] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 01/08/2017] [Accepted: 01/17/2017] [Indexed: 12/13/2022]
Abstract
Cell-based therapeutics offer diverse options for treating retinal degenerative diseases, such as age-related macular degeneration (AMD) and retinitis pigmentosa (RP). AMD is characterized by both genetic and environmental risks factors, whereas RP is mainly a monogenic disorder. Though treatments exist for some patients with neovascular AMD, a majority of retinal degenerative patients have no effective therapeutics, thus indicating a need for universal therapies to target diverse patient populations. Two main cell-based mechanistic approaches are being tested in clinical trials. Replacement therapies utilize cell-derived retinal pigment epithelial (RPE) cells to supplant lost or defective host RPE cells. These cells are similar in morphology and function to native RPE cells and can potentially supplant the responsibilities of RPE in vivo. Preservation therapies utilize supportive cells to aid in visual function and photoreceptor preservation partially by neurotrophic mechanisms. The goal of preservation strategies is to halt or slow the progression of disease and maintain remaining visual function. A number of clinical trials are testing the safety of replacement and preservation cell therapies in patients; however, measures of efficacy will need to be further evaluated. In addition, a number of prevailing concerns with regards to the immune-related response, longevity, and functionality of the grafted cells will need to be addressed in future trials. This review will summarize the current status of cell-based preclinical and clinical studies with a focus on replacement and preservation strategies and the obstacles that remain regarding these types of treatments.
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Affiliation(s)
- Melissa K Jones
- Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, 8700 Beverly Blvd., Los Angeles, CA 90048, USA; Department of Biomedical Sciences, Cedars-Sinai Medical Center, 8700 Beverly Blvd., Los Angeles, CA 90048, USA
| | - Bin Lu
- Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, 8700 Beverly Blvd., Los Angeles, CA 90048, USA; Department of Biomedical Sciences, Cedars-Sinai Medical Center, 8700 Beverly Blvd., Los Angeles, CA 90048, USA
| | - Sergey Girman
- Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, 8700 Beverly Blvd., Los Angeles, CA 90048, USA; Department of Biomedical Sciences, Cedars-Sinai Medical Center, 8700 Beverly Blvd., Los Angeles, CA 90048, USA
| | - Shaomei Wang
- Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, 8700 Beverly Blvd., Los Angeles, CA 90048, USA; Department of Biomedical Sciences, Cedars-Sinai Medical Center, 8700 Beverly Blvd., Los Angeles, CA 90048, USA; David Geffen School of Medicine, University of California Los Angeles, 10833 Le Conte Ave., Los Angeles, CA 90095, USA.
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202
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Shang P, Valapala M, Grebe R, Hose S, Ghosh S, Bhutto IA, Handa JT, Lutty GA, Lu L, Wan J, Qian J, Sergeev Y, Puertollano R, Zigler JS, Xu GT, Sinha D. The amino acid transporter SLC36A4 regulates the amino acid pool in retinal pigmented epithelial cells and mediates the mechanistic target of rapamycin, complex 1 signaling. Aging Cell 2017; 16:349-359. [PMID: 28083894 PMCID: PMC5334531 DOI: 10.1111/acel.12561] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/24/2016] [Indexed: 12/14/2022] Open
Abstract
The dry (nonneovascular) form of age‐related macular degeneration (AMD), a leading cause of blindness in the elderly, has few, if any, treatment options at present. It is characterized by early accumulation of cellular waste products in the retinal pigmented epithelium (RPE); rejuvenating impaired lysosome function in RPE is a well‐justified target for treatment. It is now clear that amino acids and vacuolar‐type H+‐ATPase (V‐ATPase) regulate the mechanistic target of rapamycin, complex 1 (mTORC1) signaling in lysosomes. Here, we provide evidence for the first time that the amino acid transporter SLC36A4/proton‐dependent amino acid transporter (PAT4) regulates the amino acid pool in the lysosomes of RPE. In Cryba1 (gene encoding βA3/A1‐crystallin) KO (knockout) mice, where PAT4 and amino acid levels are increased in the RPE, the transcription factors EB (TFEB) and E3 (TFE3) are retained in the cytoplasm, even after 24 h of fasting. Consequently, genes in the coordinated lysosomal expression and regulation (CLEAR) network are not activated, and lysosomal function remains low. As these mice age, expression of RPE65 and lecithin retinol acyltransferase (LRAT), two vital visual cycle proteins, decreases in the RPE. A defective visual cycle would possibly slow down the regeneration of new photoreceptor outer segments (POS). Further, photoreceptor degeneration also becomes obvious during aging, reminiscent of human dry AMD disease. Electron microscopy shows basal laminar deposits in Bruch's membrane, a hallmark of development of AMD. For dry AMD patients, targeting PAT4/V‐ATPase in the lysosomes of RPE cells may be an effective means of preventing or delaying disease progression.
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Affiliation(s)
- Peng Shang
- Department of Ophthalmology of Shanghai Tenth People's Hospital and Laboratory of Clinical Visual Science of Tongji Eye Institute; Tongji University School of Medicine; Shanghai China
- The Wilmer Eye Institute; The Johns Hopkins University School of Medicine; Baltimore MD USA
| | - Mallika Valapala
- The Wilmer Eye Institute; The Johns Hopkins University School of Medicine; Baltimore MD USA
| | - Rhonda Grebe
- The Wilmer Eye Institute; The Johns Hopkins University School of Medicine; Baltimore MD USA
| | - Stacey Hose
- The Wilmer Eye Institute; The Johns Hopkins University School of Medicine; Baltimore MD USA
| | - Sayan Ghosh
- The Wilmer Eye Institute; The Johns Hopkins University School of Medicine; Baltimore MD USA
| | - Imran A. Bhutto
- The Wilmer Eye Institute; The Johns Hopkins University School of Medicine; Baltimore MD USA
| | - James T. Handa
- The Wilmer Eye Institute; The Johns Hopkins University School of Medicine; Baltimore MD USA
| | - Gerard A. Lutty
- The Wilmer Eye Institute; The Johns Hopkins University School of Medicine; Baltimore MD USA
| | - Lixia Lu
- Department of Ophthalmology of Shanghai Tenth People's Hospital and Laboratory of Clinical Visual Science of Tongji Eye Institute; Tongji University School of Medicine; Shanghai China
| | - Jun Wan
- The Wilmer Eye Institute; The Johns Hopkins University School of Medicine; Baltimore MD USA
| | - Jiang Qian
- The Wilmer Eye Institute; The Johns Hopkins University School of Medicine; Baltimore MD USA
| | - Yuri Sergeev
- National Eye Institute; National Institutes of Health; Bethesda MD USA
| | - Rosa Puertollano
- Cell Biology and Physiology Center; National Heart, Lung and Blood Institute; National Institutes of Health; Bethesda MD USA
| | - J. Samuel Zigler
- The Wilmer Eye Institute; The Johns Hopkins University School of Medicine; Baltimore MD USA
| | - Guo-Tong Xu
- Department of Ophthalmology of Shanghai Tenth People's Hospital and Laboratory of Clinical Visual Science of Tongji Eye Institute; Tongji University School of Medicine; Shanghai China
- Translational Medical Center for Stem Cell Therapy; Shanghai East Hospital; Tongji University School of Medicine; Shanghai China
- The Collaborative Innovation Center for Brain Science; Tongji University; Shanghai China
| | - Debasish Sinha
- The Wilmer Eye Institute; The Johns Hopkins University School of Medicine; Baltimore MD USA
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203
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Xia T, Rizzolo LJ. Effects of diabetic retinopathy on the barrier functions of the retinal pigment epithelium. Vision Res 2017; 139:72-81. [PMID: 28347688 DOI: 10.1016/j.visres.2017.02.006] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Accepted: 02/28/2017] [Indexed: 02/06/2023]
Abstract
Diabetic retinopathy is a debilitating microvascular complication of diabetes mellitus. A rich literature describes the breakdown of retinal endothelial cells and the inner blood-retinal barrier, but the effects of diabetes on the retinal pigment epithelium (RPE) has received much less attention. RPE lies between the choroid and neurosensory retina to form the outer blood-retinal barrier. RPE's specialized and dynamic barrier functions are crucial for maintaining retinal health. RPE barrier functions include a collection of interrelated structures and activities that regulate the transepithelial movement of solutes, including: diffusion through the paracellular spaces, facilitated diffusion through the cells, active transport, receptor-mediated and bulk phase transcytosis, and metabolic processing of solutes in transit. In the later stages of diabetic retinopathy, the tight junctions that regulate the paracellular space begin to disassemble, but there are earlier effects on the other aspects of RPE barrier function, particularly active transport and metabolic processing. With advanced understanding of RPE-specific barrier functions, and more in vivo-like culture models, the time is ripe for revisiting experiments in the literature to resolve controversies and extend our understanding of how diabetes affects the outer blood-retinal barrier.
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Affiliation(s)
- Tina Xia
- Departments of Surgery and Ophthalmology and Visual Science, Yale University School of Medicine, PO Box 208062, New Haven, CT 06520-8062, USA.
| | - Lawrence J Rizzolo
- Departments of Surgery and Ophthalmology and Visual Science, Yale University School of Medicine, PO Box 208062, New Haven, CT 06520-8062, USA.
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204
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Broadgate S, Yu J, Downes SM, Halford S. Unravelling the genetics of inherited retinal dystrophies: Past, present and future. Prog Retin Eye Res 2017; 59:53-96. [PMID: 28363849 DOI: 10.1016/j.preteyeres.2017.03.003] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 03/21/2017] [Accepted: 03/23/2017] [Indexed: 02/07/2023]
Abstract
The identification of the genes underlying monogenic diseases has been of interest to clinicians and scientists for many years. Using inherited retinal dystrophies as an example of monogenic disease we describe the history of molecular genetic techniques that have been pivotal in the discovery of disease causing genes. The methods that were developed in the 1970's and 80's are still in use today but have been refined and improved. These techniques enabled the concept of the Human Genome Project to be envisaged and ultimately realised. When the successful conclusion of the project was announced in 2003 many new tools and, as importantly, many collaborations had been developed that facilitated a rapid identification of disease genes. In the post-human genome project era advances in computing power and the clever use of the properties of DNA replication has allowed the development of next-generation sequencing technologies. These methods have revolutionised the identification of disease genes because for the first time there is no need to define the position of the gene in the genome. The use of next generation sequencing in a diagnostic setting has allowed many more patients with an inherited retinal dystrophy to obtain a molecular diagnosis for their disease. The identification of novel genes that have a role in the development or maintenance of retinal function is opening up avenues of research which will lead to the development of new pharmacological and gene therapy approaches. Neither of which can be used unless the defective gene and protein is known. The continued development of sequencing technologies also holds great promise for the advent of truly personalised medicine.
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Affiliation(s)
- Suzanne Broadgate
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Levels 5 and 6 West Wing, John Radcliffe Hospital, Headley Way, Oxford, OX3 9DU, UK
| | - Jing Yu
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Levels 5 and 6 West Wing, John Radcliffe Hospital, Headley Way, Oxford, OX3 9DU, UK
| | - Susan M Downes
- Oxford Eye Hospital, Oxford University Hospitals NHS Trust, Oxford, OX3 9DU, UK
| | - Stephanie Halford
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Levels 5 and 6 West Wing, John Radcliffe Hospital, Headley Way, Oxford, OX3 9DU, UK.
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205
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Sharif W, Sharif Z. Leber's congenital amaurosis and the role of gene therapy in congenital retinal disorders. Int J Ophthalmol 2017; 10:480-484. [PMID: 28393043 DOI: 10.18240/ijo.2017.03.24] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 08/19/2016] [Indexed: 11/23/2022] Open
Abstract
Leber's congenital amaurosis (LCA) and recent gene therapy advancement for treating inherited retinopathies were extensive literature reviewed using MEDLINE, PubMed and EMBASE. Adeno-associated viral vectors were the most utilised vectors for ocular gene therapy. Cone photoreceptor cells might use an alternate pathway which was not reliant of the retinal pigment epithelium (RPE) derived retinoid isomerohydrolase (RPE65) to access the 11-cis retinal dehydechromophore. Research efforts dedicated on the progression of a gene-based therapy for the treatment of LCA2. Such gene therapy approaches were extremely successful in canine, porcine and rodent LCA2 models. The recombinant AAV2.hRPE65v2 adeno-associated vector contained the RPE65 cDNA and was replication deficient. Its in vitro injection in target cells induced RPE65 protein production. The gene therapy trials that were so far conducted for inherited retinopathies have generated promising results. Phase I clinical trials to cure LCA and choroideremia demonstrated that adeno-associated viral vectors containing RPE genes and photoreceptors respectively, could be successfully administered to inherited retinopathy patients. A phase III trial is presently ongoing and if successful, it will lead the way to additional gene therapy attempts to cure monogenic, inherited retinopathies.
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Affiliation(s)
- Walid Sharif
- Department of Ophthalmology Birmingham & Midland Eye Centre, City Hospital NHS Trust, Birmingham B18 7QH, UK
| | - Zuhair Sharif
- Institute of Ophthalmology, University College London 11-43 Bath St, London EC1V 9EL, UK
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206
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Landfried B, Samardzija M, Barben M, Schori C, Klee K, Storti F, Grimm C. Digoxin-induced retinal degeneration depends on rhodopsin. Cell Death Dis 2017; 8:e2670. [PMID: 28300845 PMCID: PMC5386584 DOI: 10.1038/cddis.2017.94] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2016] [Revised: 02/09/2017] [Accepted: 02/10/2017] [Indexed: 12/13/2022]
Abstract
Na,K-ATPases are energy consuming ion pumps that are required for maintaining ion homeostasis in most cells. In the retina, Na,K-ATPases are especially important to sustain the dark current in photoreceptor cells needed for rapid hyperpolarization of rods and cones in light. Cardiac glycosides like digoxin inhibit the activity of Na,K-ATPases by targeting their catalytic alpha subunits. This leads to a disturbed ion balance, which can affect cellular function and survival. Here we show that the treatment of wild-type mice with digoxin leads to severe retinal degeneration and loss of vision. Digoxin induced cell death specifically in photoreceptor cells with no or only minor effects in other retinal cell types. Photoreceptor-specific cytotoxicity depended on the presence of bleachable rhodopsin. Photoreceptors of Rpe65 knockouts, which have no measurable rhodopsin and photoreceptors of Rpe65R91W mice that have <10% of the rhodopsin found in retinas of wild-type mice were not sensitive to digoxin treatment. Similarly, cones in the all-cone retina of Nrl knockout mice were also not affected. Digoxin induced expression of several genes involved in stress signaling and inflammation. It also activated proteins such as ERK1/2, AKT, STAT1, STAT3 and CASP1 during a period of up to 10 days after treatment. Activation of signaling genes and proteins, as well as the dependency on bleachable rhodopsin resembles mechanisms of light-induced photoreceptor degeneration. Digoxin-mediated photoreceptor cell death may thus be used as an inducible model system to study molecular mechanisms of retinal degeneration.
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Affiliation(s)
- Britta Landfried
- Lab for Retinal Cell Biology, Department of Ophthalmology, University of Zürich, Zürich, Switzerland
| | - Marijana Samardzija
- Lab for Retinal Cell Biology, Department of Ophthalmology, University of Zürich, Zürich, Switzerland
| | - Maya Barben
- Lab for Retinal Cell Biology, Department of Ophthalmology, University of Zürich, Zürich, Switzerland.,Neuroscience Center Zürich (ZNZ), University of Zürich, Zürich, Switzerland
| | - Christian Schori
- Lab for Retinal Cell Biology, Department of Ophthalmology, University of Zürich, Zürich, Switzerland.,Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
| | - Katrin Klee
- Lab for Retinal Cell Biology, Department of Ophthalmology, University of Zürich, Zürich, Switzerland.,Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
| | - Federica Storti
- Lab for Retinal Cell Biology, Department of Ophthalmology, University of Zürich, Zürich, Switzerland
| | - Christian Grimm
- Lab for Retinal Cell Biology, Department of Ophthalmology, University of Zürich, Zürich, Switzerland.,Neuroscience Center Zürich (ZNZ), University of Zürich, Zürich, Switzerland.,Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
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207
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Sun D, Sahu B, Gao S, Schur RM, Vaidya AM, Maeda A, Palczewski K, Lu ZR. Targeted Multifunctional Lipid ECO Plasmid DNA Nanoparticles as Efficient Non-viral Gene Therapy for Leber's Congenital Amaurosis. MOLECULAR THERAPY. NUCLEIC ACIDS 2017. [PMID: 28624218 PMCID: PMC5363681 DOI: 10.1016/j.omtn.2017.02.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Development of a gene delivery system with high efficiency and a good safety profile is essential for successful gene therapy. Here we developed a targeted non-viral delivery system using a multifunctional lipid ECO for treating Leber’s congenital amaurosis type 2 (LCA2) and tested this in a mouse model. ECO formed stable nanoparticles with plasmid DNA (pDNA) at a low amine to phosphate (N/P) ratio and mediated high gene transfection efficiency in ARPE-19 cells because of their intrinsic properties of pH-sensitive amphiphilic endosomal escape and reductive cytosolic release (PERC). All-trans-retinylamine, which binds to interphotoreceptor retinoid-binding protein (IRBP), was incorporated into the nanoparticles via a polyethylene glycol (PEG) spacer for targeted delivery of pDNA into the retinal pigmented epithelium. The targeted ECO/pDNA nanoparticles provided high GFP expression in the RPE of 1-month-old Rpe65−/− mice after subretinal injection. Such mice also exhibited a significant increase in electroretinographic activity, and this therapeutic effect continued for at least 120 days. A safety study in wild-type BALB/c mice indicated no irreversible retinal damage following subretinal injection of these targeted nanoparticles. All-trans-retinylamine-modified ECO/pDNA nanoparticles provide a promising non-viral platform for safe and effective treatment of RPE-specific monogenic eye diseases such as LCA2.
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Affiliation(s)
- Da Sun
- Case Center for Biomolecular Engineering and Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Bhubanananda Sahu
- Department of Ophthalmology and Visual Sciences, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Songqi Gao
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH 44140, USA
| | - Rebecca M Schur
- Case Center for Biomolecular Engineering and Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Amita M Vaidya
- Case Center for Biomolecular Engineering and Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Akiko Maeda
- Department of Ophthalmology and Visual Sciences, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Krzysztof Palczewski
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH 44140, USA
| | - Zheng-Rong Lu
- Case Center for Biomolecular Engineering and Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, OH 44106, USA.
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208
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Tzima E, Serifi I, Tsikari I, Alzualde A, Leonardos I, Papamarcaki T. Transcriptional and Behavioral Responses of Zebrafish Larvae to Microcystin-LR Exposure. Int J Mol Sci 2017; 18:ijms18020365. [PMID: 28208772 PMCID: PMC5343900 DOI: 10.3390/ijms18020365] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Revised: 01/29/2017] [Accepted: 02/02/2017] [Indexed: 12/29/2022] Open
Abstract
Microcystins are cyclic heptapeptides that constitute a diverse group of toxins produced by cyanobacteria. One of the most toxic variants of this family is microcystin-LR (MCLR) which is a potent inhibitor of protein phosphatase 2A (PP2A) and induces cytoskeleton alterations. In this study, zebrafish larvae exposed to 500 μg/L of MCLR for four days exhibited a 40% reduction of PP2A activity compared to the controls, indicating early effects of the toxin. Gene expression profiling of the MCLR-exposed larvae using microarray analysis revealed that keratin 96 (krt96) was the most downregulated gene, consistent with the well-documented effects of MCLR on cytoskeleton structure. In addition, our analysis revealed upregulation in all genes encoding for the enzymes of the retinal visual cycle, including rpe65a (retinal pigment epithelium-specific protein 65a), which is critical for the larval vision. Quantitative real-time PCR (qPCR) analysis confirmed the microarray data, showing that rpe65a was significantly upregulated at 50 μg/L and 500 μg/L MCLR in a dose-dependent manner. Consistent with the microarray data, MCLR-treated larvae displayed behavioral alterations such as weakening response to the sudden darkness and hypoactivity in the dark. Our work reveals new molecular targets for MCLR and provides further insights into the molecular mechanisms of MCLR toxicity during early development.
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Affiliation(s)
- Eleni Tzima
- Laboratory of Biological Chemistry, Medical School, University of Ioannina, 45110 Ioannina, Greece.
- Division of Biomedical Research, Foundation for Research and Technology-Hellas, Institute of Molecular Biology and Biotechnology, 45110 Ιοannina, Greece.
| | - Iliana Serifi
- Laboratory of Biological Chemistry, Medical School, University of Ioannina, 45110 Ioannina, Greece.
- Division of Biomedical Research, Foundation for Research and Technology-Hellas, Institute of Molecular Biology and Biotechnology, 45110 Ιοannina, Greece.
| | - Ioanna Tsikari
- Laboratory of Biological Chemistry, Medical School, University of Ioannina, 45110 Ioannina, Greece.
| | | | - Ioannis Leonardos
- Laboratory of Zoology, Department of Biological Applications and Technologies, University of Ioannina, 45110 Ioannina, Greece.
| | - Thomais Papamarcaki
- Laboratory of Biological Chemistry, Medical School, University of Ioannina, 45110 Ioannina, Greece.
- Division of Biomedical Research, Foundation for Research and Technology-Hellas, Institute of Molecular Biology and Biotechnology, 45110 Ιοannina, Greece.
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209
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Arne JM, Widjaja-Adhi MAK, Hughes T, Huynh KW, Silvaroli JA, Chelstowska S, Moiseenkova-Bell VY, Golczak M. Allosteric modulation of the substrate specificity of acyl-CoA wax alcohol acyltransferase 2. J Lipid Res 2017; 58:719-730. [PMID: 28096191 DOI: 10.1194/jlr.m073692] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 01/06/2017] [Indexed: 01/30/2023] Open
Abstract
The esterification of alcohols with fatty acids is a universal mechanism to form inert storage forms of sterols, di- and triacylglycerols, and retinoids. In ocular tissues, formation of retinyl esters is an essential step in the enzymatic regeneration of the visual chromophore (11-cis-retinal). Acyl-CoA wax alcohol acyltransferase 2 (AWAT2), also known as multifunctional O-acyltransferase (MFAT), is an integral membrane enzyme with a broad substrate specificity that has been shown to preferentially esterify 11-cis-retinol and thus contribute to formation of a readily available pool of cis retinoids in the eye. However, the mechanism by which this promiscuous enzyme can gain substrate specificity is unknown. Here, we provide evidence for an allosteric modulation of the enzymatic activity by 11-cis retinoids. This regulation is independent from cellular retinaldehyde-binding protein (CRALBP), the major cis-retinoid binding protein. This positive-feedback regulation leads to decreased esterification rates for 9-cis, 13-cis, or all-trans retinols and thus enables preferential synthesis of 11-cis-retinyl esters. Finally, electron microscopy analyses of the purified enzyme indicate that this allosteric effect does not result from formation of functional oligomers. Altogether, these data provide the experimental basis for understanding regulation of AWAT2 substrate specificity.
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Affiliation(s)
- Jason M Arne
- Department of Pharmacology and School of Medicine, Case Western Reserve University, Cleveland, OH
| | | | - Taylor Hughes
- Department of Pharmacology and School of Medicine, Case Western Reserve University, Cleveland, OH
| | - Kevin W Huynh
- Department of Pharmacology and School of Medicine, Case Western Reserve University, Cleveland, OH
| | - Josie A Silvaroli
- Department of Pharmacology and School of Medicine, Case Western Reserve University, Cleveland, OH
| | - Sylwia Chelstowska
- Department of Pharmacology and School of Medicine, Case Western Reserve University, Cleveland, OH; Laboratory of Hematology and Flow Cytometry, Department of Hematology, Military Institute of Medicine, Warsaw, Poland
| | - Vera Y Moiseenkova-Bell
- Department of Pharmacology and School of Medicine, Case Western Reserve University, Cleveland, OH; Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH; and
| | - Marcin Golczak
- Department of Pharmacology and School of Medicine, Case Western Reserve University, Cleveland, OH; Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH; and.
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210
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Abstract
As our understanding of the genetic basis for inherited retinal disease has expanded, gene therapy has advanced into clinical development. When the gene mutations associated with inherited retinal dystrophies were identified, it became possible to create animal models in which individual gene were altered to match the human mutations. The retina of these animals were then characterized to assess whether the mutated genes produced retinal phenotypes characteristic of disease-affected patients. Following the identification of a subpopulation of patients with the affected gene and the development of techniques for the viral gene transduction of retinal cells, it has become possible to deliver a copy of the normal gene into the retinal sites of the mutated genes. When this was performed in animal models of monogenic diseases, at an early stage of retinal degeneration when the affected cells remained viable, successful gene augmentation corrected the structural and functional lesions characteristic of the specific diseases in the areas of the retina that were successfully transduced. These studies provided the essential proof-of-concept needed to advance monogenic gene therapies into clinic development; these therapies include treatments for: Leber's congenital amaurosis type 2, caused by mutations to RPE65, retinoid isomerohydrolase; choroideremia, caused by mutations to REP1, Rab escort protein 1; autosomal recessive Stargardt disease, caused by mutations to ABCA4, the photoreceptor-specific ATP-binding transporter; Usher 1B disease caused by mutations to MYO7A, myosin heavy chain 7; X-linked juvenile retinoschisis caused by mutations to RS1, retinoschisin; autosomal recessive retinitis pigmentosa caused by mutations to MERTK, the proto-oncogene tyrosine-protein kinase MER; Leber's hereditary optic neuropathy caused by mutations to ND4, mitochondrial nicotinamide adenine dinucleotide ubiquinone oxidoreductase (complex I) subunit 4 and achromatopsia, caused by mutations to CNGA3, cyclic nucleotide-gated channel alpha 3 and CNGB3, cyclic nucleotide-gated channel beta 3. This review includes a tabulated summary of treatments for these monogenic retinal dystrophies that have entered into clinical development, as well as a brief summary of the preclinical data that supported their advancement into clinical development.
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211
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Shin Y, Moiseyev G, Chakraborty D, Ma JX. A Dominant Mutation in Rpe65, D477G, Delays Dark Adaptation and Disturbs the Visual Cycle in the Mutant Knock-In Mice. THE AMERICAN JOURNAL OF PATHOLOGY 2016; 187:517-527. [PMID: 28041994 DOI: 10.1016/j.ajpath.2016.11.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 11/01/2016] [Accepted: 11/03/2016] [Indexed: 01/09/2023]
Abstract
RPE65 is an indispensable component of the retinoid visual cycle in vertebrates, through which the visual chromophore 11-cis-retinal (11-cis-RAL) is generated to maintain normal vision. Various blinding conditions in humans, such as Leber congenital amaurosis and retinitis pigmentosa (RP), are attributed to either homozygous or compound heterozygous mutations in RPE65. Herein, we investigated D477G missense mutation, an unprecedented dominant-acting mutation of RPE65 identified in patients with autosomal dominant RP. We generated a D477G knock-in (KI) mouse and characterized its phenotypes. Although RPE65 protein levels were decreased in heterozygous KI mice, their scotopic, maximal, and photopic electroretinography responses were comparable to those of wild-type (WT) mice in stationary condition. As shown by high-performance liquid chromatography analysis, levels of 11-cis-RAL in fully dark-adapted heterozygous KI mice were similar to that in WT mice. However, kinetics of 11-cis-RAL regeneration after light exposure were significantly slower in heterozygous KI mice compared with WT and RPE65 heterozygous knockout mice. Furthermore, heterozygous KI mice exhibited lower A-wave recovery compared with WT mice after photobleaching, suggesting a delayed dark adaptation. Taken together, these observations suggest that D477G acts as a dominant-negative mutant of RPE65 that delays chromophore regeneration. The KI mice provide a useful model for further understanding of the pathogenesis of RP associated with this RPE65 mutant and for the development of therapeutic strategies.
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Affiliation(s)
- Younghwa Shin
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Gennadiy Moiseyev
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Dibyendu Chakraborty
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Jian-Xing Ma
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma.
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212
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Georgiadis A, Duran Y, Ribeiro J, Abelleira-Hervas L, Robbie SJ, Sünkel-Laing B, Fourali S, Gonzalez-Cordero A, Cristante E, Michaelides M, Bainbridge JWB, Smith AJ, Ali RR. Development of an optimized AAV2/5 gene therapy vector for Leber congenital amaurosis owing to defects in RPE65. Gene Ther 2016; 23:857-862. [PMID: 27653967 PMCID: PMC5143366 DOI: 10.1038/gt.2016.66] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 08/18/2016] [Accepted: 08/26/2016] [Indexed: 12/02/2022]
Abstract
Leber congenital amaurosis is a group of inherited retinal dystrophies that cause severe sight impairment in childhood; RPE65-deficiency causes impaired rod photoreceptor function from birth and progressive impairment of cone photoreceptor function associated with retinal degeneration. In animal models of RPE65 deficiency, subretinal injection of recombinant adeno-associated virus (AAV) 2/2 vectors carrying RPE65 cDNA improves rod photoreceptor function, and intervention at an early stage of disease provides sustained benefit by protecting cone photoreceptors against retinal degeneration. In affected humans, administration of these vectors has resulted to date in relatively modest improvements in photoreceptor function, even when retinal degeneration is comparatively mild, and the duration of benefit is limited by progressive retinal degeneration. We conclude that the demand for RPE65 in humans is not fully met by current vectors, and predict that a more powerful vector will provide more durable benefit. With this aim we have modified the original AAV2/2 vector to generate AAV2/5-OPTIRPE65. The new configuration consists of an AAV vector serotype 5 carrying an optimized hRPE65 promoter and a codon-optimized hRPE65 gene. In mice, AAV2/5-OPTIRPE65 is at least 300-fold more potent than our original AAV2/2 vector.
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Affiliation(s)
- A Georgiadis
- Department of Genetics, UCL Institute of Ophthalmology, London EC1V 9EL, UK
| | - Y Duran
- Department of Genetics, UCL Institute of Ophthalmology, London EC1V 9EL, UK
| | - J Ribeiro
- Department of Genetics, UCL Institute of Ophthalmology, London EC1V 9EL, UK
| | - L Abelleira-Hervas
- Department of Genetics, UCL Institute of Ophthalmology, London EC1V 9EL, UK
| | - S J Robbie
- Department of Genetics, UCL Institute of Ophthalmology, London EC1V 9EL, UK
| | - B Sünkel-Laing
- Department of Genetics, UCL Institute of Ophthalmology, London EC1V 9EL, UK
| | - S Fourali
- Department of Genetics, UCL Institute of Ophthalmology, London EC1V 9EL, UK
| | - A Gonzalez-Cordero
- Department of Genetics, UCL Institute of Ophthalmology, London EC1V 9EL, UK
| | - E Cristante
- Department of Genetics, UCL Institute of Ophthalmology, London EC1V 9EL, UK
| | - M Michaelides
- Department of Genetics, UCL Institute of Ophthalmology, London EC1V 9EL, UK
- NIHR Biomedical Research Centre at Moorfields Eye Hospital, London EC1V 2PD, UK
| | - J W B Bainbridge
- Department of Genetics, UCL Institute of Ophthalmology, London EC1V 9EL, UK
- NIHR Biomedical Research Centre at Moorfields Eye Hospital, London EC1V 2PD, UK
| | - A J Smith
- Department of Genetics, UCL Institute of Ophthalmology, London EC1V 9EL, UK
| | - R R Ali
- Department of Genetics, UCL Institute of Ophthalmology, London EC1V 9EL, UK
- NIHR Biomedical Research Centre at Moorfields Eye Hospital, London EC1V 2PD, UK
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213
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The Warburg Effect Mediator Pyruvate Kinase M2 Expression and Regulation in the Retina. Sci Rep 2016; 6:37727. [PMID: 27883057 PMCID: PMC5121888 DOI: 10.1038/srep37727] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 10/31/2016] [Indexed: 01/06/2023] Open
Abstract
The tumor form of pyruvate kinase M2 (PKM2) undergoes tyrosine phosphorylation and gives rise to the Warburg effect. The Warburg effect defines a pro-oncogenic metabolism switch such that cancer cells take up more glucose than normal tissue and favor incomplete oxidation of glucose, even in the presence of oxygen. Retinal photoreceptors are highly metabolic and their energy consumption is equivalent to that of a multiplying tumor cell. In the present study, we found that PKM2 is the predominant isoform in both rod- and cone-dominant retina, and that it undergoes a light-dependent tyrosine phosphorylation. We also discovered that PKM2 phosphorylation is signaled through photobleaching of rhodopsin. Our findings suggest that phosphoinositide 3-kinase activation promotes PKM2 phosphorylation. Light and tyrosine phosphorylation appear to regulate PKM2 to provide a metabolic advantage to photoreceptor cells, thereby promoting cell survival.
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214
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Palczewska G, Maeda A, Golczak M, Arai E, Dong Z, Perusek L, Kevany B, Palczewski K. Receptor MER Tyrosine Kinase Proto-oncogene (MERTK) Is Not Required for Transfer of Bis-retinoids to the Retinal Pigmented Epithelium. J Biol Chem 2016; 291:26937-26949. [PMID: 27875314 DOI: 10.1074/jbc.m116.764563] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 11/14/2016] [Indexed: 01/08/2023] Open
Abstract
Accumulation of bis-retinoids in the retinal pigmented epithelium (RPE) is a hallmark of aging and retinal disorders such as Stargardt disease and age-related macular degeneration. These aberrant fluorescent condensation products, including di-retinoid-pyridinium-ethanolamine (A2E), are thought to be transferred to RPE cells primarily through phagocytosis of the photoreceptor outer segments. However, we observed by two-photon microscopy that mouse retinas incapable of phagocytosis due to a deficiency of the c-Mer proto-oncogene tyrosine kinase (Mertk) nonetheless contained fluorescent retinoid condensation material in their RPE. Primary RPE cells from Mertk-/- mice also accumulated fluorescent products in vitro Finally, quantification of A2E demonstrated the acquisition of retinal condensation products in Mertk-/- mouse RPE prior to retinal degeneration. In these mice, we identified activated microglial cells that likely were recruited to transport A2E-like condensation products to the RPE and dispose of the dying photoreceptor cells. These observations demonstrate a novel transport mechanism between photoreceptor cells and RPE that does not involve canonical Mertk-dependent phagocytosis.
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Affiliation(s)
| | - Akiko Maeda
- the Departments of Ophthalmology and Visual Sciences and
| | - Marcin Golczak
- Pharmacology and Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
| | - Eisuke Arai
- the Departments of Ophthalmology and Visual Sciences and
| | | | | | - Brian Kevany
- Pharmacology and Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
| | - Krzysztof Palczewski
- Pharmacology and Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
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215
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Molecular Basis for Vitamin A Uptake and Storage in Vertebrates. Nutrients 2016; 8:nu8110676. [PMID: 27792183 PMCID: PMC5133064 DOI: 10.3390/nu8110676] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 09/30/2016] [Accepted: 10/18/2016] [Indexed: 01/27/2023] Open
Abstract
The ability to store and distribute vitamin A inside the body is the main evolutionary adaptation that allows vertebrates to maintain retinoid functions during nutritional deficiencies and to acquire new metabolic pathways enabling light-independent production of 11-cis retinoids. These processes greatly depend on enzymes that esterify vitamin A as well as associated retinoid binding proteins. Although the significance of retinyl esters for vitamin A homeostasis is well established, until recently, the molecular basis for the retinol esterification enzymatic activity was unknown. In this review, we will look at retinoid absorption through the prism of current biochemical and structural studies on vitamin A esterifying enzymes. We describe molecular adaptations that enable retinoid storage and delineate mechanisms in which mutations found in selective proteins might influence vitamin A homeostasis in affected patients.
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216
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Yang F, Ma H, Belcher J, Butler MR, Redmond TM, Boye SL, Hauswirth WW, Ding XQ. Targeting iodothyronine deiodinases locally in the retina is a therapeutic strategy for retinal degeneration. FASEB J 2016; 30:4313-4325. [PMID: 27623928 DOI: 10.1096/fj.201600715r] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 09/01/2016] [Indexed: 12/21/2022]
Abstract
Recent studies have implicated thyroid hormone (TH) signaling in cone photoreceptor viability. Using mouse models of retinal degeneration, we found that antithyroid treatment preserves cones. This work investigates the significance of targeting intracellular TH components locally in the retina. The cellular TH level is mainly regulated by deiodinase iodothyronine (DIO)-2 and -3. DIO2 converts thyroxine (T4) to triiodothyronine (T3), which binds to the TH receptor, whereas DIO3 degrades T3 and T4. We examined cone survival after overexpression of DIO3 and inhibition of DIO2 and demonstrated the benefits of these manipulations. Subretinal delivery of AAV5-IRBP/GNAT2-DIO3, which directs expression of human DIO3 specifically in cones, increased cone density by 30-40% in a Rpe65-/- mouse model of Lebers congenital amaurosis (LCA) and in a Cpfl1 mouse with Pde6c defect model of achromatopsia, compared with their respective untreated controls. Intravitreal and topical delivery of the DIO2 inhibitor iopanoic acid also significantly improved cone survival in the LCA model mice. Moreover, the expression levels of DIO2 and Slc16a2 were significantly higher in the diseased retinas, suggesting locally elevated TH signaling. We show that targeting DIOs protects cones, and intracellular inhibition of TH components locally in the retina may represent a novel strategy for retinal degeneration management.-Yang, F., Ma, H., Belcher, J., Butler, M. R., Redmond, T. M., Boye, S. L., Hauswirth, W. W., Ding, X.-Q. Targeting iodothyronine deiodinases locally in the retina is a therapeutic strategy for retinal degeneration.
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Affiliation(s)
- Fan Yang
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Hongwei Ma
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Joshua Belcher
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Michael R Butler
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - T Michael Redmond
- Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, Bethesda, Maryland, USA
| | - Sanford L Boye
- Department of Ophthalmology, University of Florida, Gainesville, Florida, USA; and.,Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida, USA
| | - William W Hauswirth
- Department of Ophthalmology, University of Florida, Gainesville, Florida, USA; and.,Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida, USA
| | - Xi-Qin Ding
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA;
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217
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Bennett J, Wellman J, Marshall KA, McCague S, Ashtari M, DiStefano-Pappas J, Elci OU, Chung DC, Sun J, Wright JF, Cross DR, Aravand P, Cyckowski LL, Bennicelli JL, Mingozzi F, Auricchio A, Pierce EA, Ruggiero J, Leroy BP, Simonelli F, High KA, Maguire AM. Safety and durability of effect of contralateral-eye administration of AAV2 gene therapy in patients with childhood-onset blindness caused by RPE65 mutations: a follow-on phase 1 trial. Lancet 2016; 388:661-72. [PMID: 27375040 PMCID: PMC5351775 DOI: 10.1016/s0140-6736(16)30371-3] [Citation(s) in RCA: 329] [Impact Index Per Article: 41.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
BACKGROUND Safety and efficacy have been shown in a phase 1 dose-escalation study involving a unilateral subretinal injection of a recombinant adeno-associated virus (AAV) vector containing the RPE65 gene (AAV2-hRPE65v2) in individuals with inherited retinal dystrophy caused by RPE65 mutations. This finding, along with the bilateral nature of the disease and intended use in treatment, prompted us to determine the safety of administration of AAV2-hRPE65v2 to the contralateral eye in patients enrolled in the phase 1 study. METHODS In this follow-on phase 1 trial, one dose of AAV2-hRPE65v2 (1.5 × 10(11) vector genomes) in a total volume of 300 μL was subretinally injected into the contralateral, previously uninjected, eyes of 11 children and adults (aged 11-46 years at second administration) with inherited retinal dystrophy caused by RPE65 mutations, 1.71-4.58 years after the initial subretinal injection. We assessed safety, immune response, retinal and visual function, functional vision, and activation of the visual cortex from baseline until 3 year follow-up, with observations ongoing. This study is registered with ClinicalTrials.gov, number NCT01208389. FINDINGS No adverse events related to the AAV were reported, and those related to the procedure were mostly mild (dellen formation in three patients and cataracts in two). One patient developed bacterial endophthalmitis and was excluded from analyses. We noted improvements in efficacy outcomes in most patients without significant immunogenicity. Compared with baseline, pooled analysis of ten participants showed improvements in mean mobility and full-field light sensitivity in the injected eye by day 30 that persisted to year 3 (mobility p=0.0003, white light full-field sensitivity p<0.0001), but no significant change was seen in the previously injected eyes over the same time period (mobility p=0.7398, white light full-field sensitivity p=0.6709). Changes in visual acuity from baseline to year 3 were not significant in pooled analysis in the second eyes or the previously injected eyes (p>0.49 for all time-points compared with baseline). INTERPRETATION To our knowledge, AAV2-hRPE65v2 is the first successful gene therapy administered to the contralateral eye. The results highlight the use of several outcome measures and help to delineate the variables that contribute to maximal benefit from gene augmentation therapy in this disease. FUNDING Center for Cellular and Molecular Therapeutics at The Children's Hospital of Philadelphia, Spark Therapeutics, US National Institutes of Health, Foundation Fighting Blindness, Institute for Translational Medicine and Therapeutics, Research to Prevent Blindness, Center for Advanced Retinal and Ocular Therapeutics, Mackall Foundation Trust, F M Kirby Foundation, and The Research Foundation-Flanders.
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Affiliation(s)
- Jean Bennett
- Center for Advanced Retinal and Ocular Therapeutics, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA; F M Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA; Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA.
| | - Jennifer Wellman
- Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Spark Therapeutics, Philadelphia, PA, USA
| | - Kathleen A Marshall
- Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Sarah McCague
- Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Manzar Ashtari
- Center for Advanced Retinal and Ocular Therapeutics, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA; F M Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA; Department of Radiology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Julie DiStefano-Pappas
- Westat Biostatistics and Data Management Core, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Okan U Elci
- Westat Biostatistics and Data Management Core, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Daniel C Chung
- Center for Advanced Retinal and Ocular Therapeutics, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA; F M Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA; Spark Therapeutics, Philadelphia, PA, USA
| | - Junwei Sun
- Center for Advanced Retinal and Ocular Therapeutics, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA; Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - J Fraser Wright
- Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Spark Therapeutics, Philadelphia, PA, USA
| | - Dominique R Cross
- Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Puya Aravand
- Center for Advanced Retinal and Ocular Therapeutics, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Laura L Cyckowski
- Department of Radiology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Jeannette L Bennicelli
- Center for Advanced Retinal and Ocular Therapeutics, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA; F M Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Federico Mingozzi
- Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Immunology and Liver Gene Therapy, Généthon, Èvry, France
| | - Alberto Auricchio
- Telethon Institute of Genetics and Medicine, Naples, Italy; Medical Genetics, Department of Pediatrics, University of Naples Federico II, Naples, Italy
| | - Eric A Pierce
- F M Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA; Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA; Department of Ophthalmology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA, USA
| | - Jason Ruggiero
- Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Bart P Leroy
- Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Ophthalmology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Ophthalmology and Center for Medical Genetics, Ghent University Hospital and Ghent University, Ghent, Belgium
| | - Francesca Simonelli
- Eye Clinic, Multidisciplinary Department of Medical, Surgical and Dental Sciences, Second University of Naples, Naples, Italy
| | - Katherine A High
- Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Spark Therapeutics, Philadelphia, PA, USA; Howard Hughes Medical Institute, Philadelphia, PA, USA
| | - Albert M Maguire
- Center for Advanced Retinal and Ocular Therapeutics, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA; F M Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA; Department of Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA; Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Ophthalmology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
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218
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Abstract
Recent progress in molecular understanding of the retinoid cycle in mammalian retina stems from painstaking biochemical reconstitution studies supported by natural or engineered animal models with known genetic lesions and studies of humans with specific genetic blinding diseases. Structural and membrane biology have been used to detect critical retinal enzymes and proteins and their substrates and ligands, placing them in a cellular context. These studies have been supplemented by analytical chemistry methods that have identified small molecules by their spectral characteristics, often in conjunction with the evaluation of models of animal retinal disease. It is from this background that rational therapeutic interventions to correct genetic defects or environmental insults are identified. Thus, most presently accepted modulators of the retinoid cycle already have demonstrated promising results in animal models of retinal degeneration. These encouraging signs indicate that some human blinding diseases can be alleviated by pharmacological interventions.
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Affiliation(s)
- Philip D Kiser
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106 ; Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio 44106
| | - Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
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219
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Miyagishima KJ, Wan Q, Corneo B, Sharma R, Lotfi MR, Boles NC, Hua F, Maminishkis A, Zhang C, Blenkinsop T, Khristov V, Jha BS, Memon OS, D'Souza S, Temple S, Miller SS, Bharti K. In Pursuit of Authenticity: Induced Pluripotent Stem Cell-Derived Retinal Pigment Epithelium for Clinical Applications. Stem Cells Transl Med 2016; 5:1562-1574. [PMID: 27400791 PMCID: PMC5070511 DOI: 10.5966/sctm.2016-0037] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 04/18/2016] [Indexed: 12/12/2022] Open
Abstract
For effective treatment, induced pluripotent stem cell (iPSC)-retinal pigment epithelium (RPE) must recapitulate the physiology of native human RPE cells. A set of physiologically relevant functional assays that assess the polarized functional activity and maturation state of the intact RPE monolayer is provided. The study data show that donor-to-donor variability exceeds the tissue-to-tissue variability for a given donor and provides, for the first time, criteria necessary to identify iPSC-RPE cells most suitable for clinical application. Induced pluripotent stem cells (iPSCs) can be efficiently differentiated into retinal pigment epithelium (RPE), offering the possibility of autologous cell replacement therapy for retinal degeneration stemming from RPE loss. The generation and maintenance of epithelial apical-basolateral polarity is fundamental for iPSC-derived RPE (iPSC-RPE) to recapitulate native RPE structure and function. Presently, no criteria have been established to determine clonal or donor based heterogeneity in the polarization and maturation state of iPSC-RPE. We provide an unbiased structural, molecular, and physiological evaluation of 15 iPSC-RPE that have been derived from distinct tissues from several different donors. We assessed the intact RPE monolayer in terms of an ATP-dependent signaling pathway that drives critical aspects of RPE function, including calcium and electrophysiological responses, as well as steady-state fluid transport. These responses have key in vivo counterparts that together help determine the homeostasis of the distal retina. We characterized the donor and clonal variation and found that iPSC-RPE function was more significantly affected by the genetic differences between different donors than the epigenetic differences associated with different starting tissues. This study provides a reference dataset to authenticate genetically diverse iPSC-RPE derived for clinical applications. Significance The retinal pigment epithelium (RPE) is essential for maintaining visual function. RPE derived from human induced pluripotent stem cells (iPSC-RPE) offer a promising cell-based transplantation therapy for slowing or rescuing RPE-induced visual function loss. For effective treatment, iPSC-RPE must recapitulate the physiology of native human RPE. A set of physiologically relevant functional assays are provided that assess the polarized functional activity and maturation state of the intact RPE monolayer. The present data show that donor-to-donor variability exceeds the tissue-to-tissue variability for a given donor and provides, for the first time, criteria necessary to identify iPSC-RPE most suitable for clinical application.
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Affiliation(s)
- Kiyoharu J Miyagishima
- Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Qin Wan
- Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Barbara Corneo
- Columbia Stem Cell Core Facility, Columbia University Medical Center, New York, New York, USA
| | - Ruchi Sharma
- Unit on Ocular and Stem Cell Translational Research, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Mostafa R Lotfi
- Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | | | - Fang Hua
- Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Arvydas Maminishkis
- Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Congxiao Zhang
- Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Timothy Blenkinsop
- Department of Development and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Vladimir Khristov
- Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Balendu S Jha
- Unit on Ocular and Stem Cell Translational Research, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Omar S Memon
- Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Sunita D'Souza
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Sally Temple
- Neural Stem Cell Institute, Rensselaer, New York, USA
| | - Sheldon S Miller
- Section on Epithelial and Retinal Physiology and Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Kapil Bharti
- Unit on Ocular and Stem Cell Translational Research, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
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220
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Wu L, Guo X, Wang W, Medeiros DM, Clarke SL, Lucas EA, Smith BJ, Lin D. Molecular aspects of β, β-carotene-9', 10'-oxygenase 2 in carotenoid metabolism and diseases. Exp Biol Med (Maywood) 2016; 241:1879-1887. [PMID: 27390265 DOI: 10.1177/1535370216657900] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 06/09/2016] [Indexed: 12/18/2022] Open
Abstract
Carotenoids, the carotenes and xanthophylls, are essential components in human nutrition. β, β-carotene-9', 10'-oxygenase 2 (BCO2), also named as β, β-carotene-9', 10'-dioxygenase 2 (BCDO2) catalyzes the asymmetrical cleavage of carotenoids, whereas β, β-carotene-15, 15'-monooxygenase (BCMO1) conducts the symmetrical cleavage of pro-vitamin A carotenoids into retinoid. Unlike BCMO1, BCO2 has a broader substrate specificity and has been considered an alternative way to produce vitamin A. In contrast to BCMO1, a cytoplasmic protein, BCO2 is located in the inner mitochondrial membrane. The difference in cellular compartmentalization may reflect the different substrate specificity and physiological functions with respect to BCMO1 and BCO2. The BCO2 gene mutations are proven to be associated with yellow color of skin and fat tissue and milk in livestock. Mutation in intron 2 of BCO2 gene is also supposed to be related to the expression of IL-18, a pro-inflammatory cytokine associated with obesity, cardiovascular diseases, and type 2 diabetes. Further, BCO2 is associated with the development of mitochondrial oxidative stress, macular degeneration, anemia, and hepatic steatosis. This review of the literature will mostly address recent updates regarding the role of BCO2 in carotenoid metabolism, and discuss the potential impacts of BCO2 protein and the mutations in mammalian diseases.
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Affiliation(s)
- Lei Wu
- Department of Nutritional Sciences, Oklahoma State University, Stillwater, OK 74078, USA
| | - Xin Guo
- Department of Nutritional Sciences, Oklahoma State University, Stillwater, OK 74078, USA
| | - Weiqun Wang
- Department of Food Nutrition Dietetics & Health, Kansas State University, Manhattan, KS 66506, USA
| | - Denis M Medeiros
- College of Graduate Studies, University of Missouri-Kansas City, Kansas City, MO 64112, USA
| | - Stephen L Clarke
- Department of Nutritional Sciences, Oklahoma State University, Stillwater, OK 74078, USA
| | - Edralin A Lucas
- Department of Nutritional Sciences, Oklahoma State University, Stillwater, OK 74078, USA
| | - Brenda J Smith
- Department of Nutritional Sciences, Oklahoma State University, Stillwater, OK 74078, USA
| | - Dingbo Lin
- Department of Nutritional Sciences, Oklahoma State University, Stillwater, OK 74078, USA
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221
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Khan KN, Mahroo OA, Khan RS, Mohamed MD, McKibbin M, Bird A, Michaelides M, Tufail A, Moore AT. Differentiating drusen: Drusen and drusen-like appearances associated with ageing, age-related macular degeneration, inherited eye disease and other pathological processes. Prog Retin Eye Res 2016; 53:70-106. [DOI: 10.1016/j.preteyeres.2016.04.008] [Citation(s) in RCA: 122] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Revised: 04/24/2016] [Accepted: 04/27/2016] [Indexed: 12/11/2022]
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Polosa A, Bessaklia H, Lachapelle P. Strain Differences in Light-Induced Retinopathy. PLoS One 2016; 11:e0158082. [PMID: 27355622 PMCID: PMC4927188 DOI: 10.1371/journal.pone.0158082] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 06/09/2016] [Indexed: 11/18/2022] Open
Abstract
The purpose of this study was to better understand the role of ocular pigmentation and genetics in light-induced retinal damage. Adult pigmented [Long Evans (LE) and Brown Norway (BN)] and albino [Sprague Dawley (SD) and Lewis (LW)] rats were exposed to a bright cyclic light for 6 consecutive days and where compared with juvenile animals exposed to the same bright light environment from postnatal age 14 to 28. Flash ERGs and retinal histology were performed at predetermined days (D) post-light exposure. At D1, ERGs were similar in all adult groups with no recordable a-waves and residual b-waves. A transient recovery was noticed at D30 in the LW and LE only [b-wave: 18% and 25% of their original amplitude respectively]. Histology revealed that BN retina was the most damaged, while LE retina was best preserved. SD and LW rats were almost as damaged as BN rats. In contrast, the retina of juvenile BN was almost as resistant to the bright light exposure as that of juvenile LE rats. Our results strongly suggest that, although ocular pigmentation and genetic background are important factors in regulating the severity of light-induced retinal damage, the age of the animal at the onset of light exposure appears to be the most important determining factor.
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Affiliation(s)
- Anna Polosa
- Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada
- Department of Ophthalmology, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Hyba Bessaklia
- Department of Ophthalmology, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Pierre Lachapelle
- Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada
- Department of Ophthalmology, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
- * E-mail:
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223
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Yu-Wai-Man P. Genetic manipulation for inherited neurodegenerative diseases: myth or reality? Br J Ophthalmol 2016; 100:1322-31. [PMID: 27002113 PMCID: PMC5050284 DOI: 10.1136/bjophthalmol-2015-308329] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 02/28/2016] [Indexed: 12/22/2022]
Abstract
Rare genetic diseases affect about 7% of the general population and over 7000 distinct clinical syndromes have been described with the majority being due to single gene defects. This review will provide a critical overview of genetic strategies that are being pioneered to halt or reverse disease progression in inherited neurodegenerative diseases. This field of research covers a vast area and only the most promising treatment paradigms will be discussed with a particular focus on inherited eye diseases, which have paved the way for innovative gene therapy paradigms, and mitochondrial diseases, which are currently generating a lot of debate centred on the bioethics of germline manipulation.
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Affiliation(s)
- Patrick Yu-Wai-Man
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK Newcastle Eye Centre, Royal Victoria Infirmary, Newcastle upon Tyne, UK NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, UK
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224
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Blenkinsop TA, Saini JS, Maminishkis A, Bharti K, Wan Q, Banzon T, Lotfi M, Davis J, Singh D, Rizzolo LJ, Miller S, Temple S, Stern JH. Human Adult Retinal Pigment Epithelial Stem Cell-Derived RPE Monolayers Exhibit Key Physiological Characteristics of Native Tissue. Invest Ophthalmol Vis Sci 2016; 56:7085-99. [PMID: 26540654 DOI: 10.1167/iovs.14-16246] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
PURPOSE We tested what native features have been preserved with a new culture protocol for adult human RPE. METHODS We cultured RPE from adult human eyes. Standard protocols for immunohistochemistry, electron microscopy, electrophysiology, fluid transport, and ELISA were used. RESULTS Confluent monolayers of adult human RPE cultures exhibit characteristics of native RPE. Immunohistochemistry demonstrated polarized expression of RPE markers. Electron microscopy illustrated characteristics of native RPE. The mean transepithelial potential (TEP) was 1.19 ± 0.24 mV (mean ± SEM, n = 31), apical positive, and the mean transepithelial resistance (RT) was 178.7 ± 9.9 Ω·cm2 (mean ± SEM, n = 31). Application of 100 μM adenosine triphosphate (ATP) apically increased net fluid absorption (Jv) by 6.11 ± 0.53 μL·cm2·h-1 (mean ± SEM, n = 6) and TEP by 0.33 ± 0.048 mV (mean ± SEM, n = 25). Gene expression of cultured RPE was comparable to native adult RPE (n = 5); however, native RPE RNA was harvested between 24 and 40 hours after death and, therefore, may not accurately reflect healthy native RPE. Vascular endothelial growth factor secreted preferentially basally 2582 ± 146 pg/mL/d, compared to an apical secretion of 1548 ± 162 pg/mL/d (n = 14, P < 0.01), while PEDF preferentially secreted apically 1487 ± 280 ng/mL/d compared to a basolateral secretion of 864 ± 132 ng/mL/d (n = 14, P < 0.01). CONCLUSIONS The new culture model preserves native RPE morphology, electrophysiology, and gene and protein expression patterns, and may be a useful model to study RPE physiology, disease, and transplantation.
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Affiliation(s)
| | - Janmeet S Saini
- Neural Stem Cell Institute, Rensselaer, New York, United States
| | - Arvydas Maminishkis
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Kapil Bharti
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Qin Wan
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Tina Banzon
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Mostafa Lotfi
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Janine Davis
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Deepti Singh
- Yale University, New Haven, Connecticut, United States
| | | | - Sheldon Miller
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Sally Temple
- Neural Stem Cell Institute, Rensselaer, New York, United States
| | - Jeffrey H Stern
- Neural Stem Cell Institute, Rensselaer, New York, United States
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225
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Rao KN, Li L, Zhang W, Brush RS, Rajala RVS, Khanna H. Loss of human disease protein retinitis pigmentosa GTPase regulator (RPGR) differentially affects rod or cone-enriched retina. Hum Mol Genet 2016; 25:1345-56. [PMID: 26908598 DOI: 10.1093/hmg/ddw017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 01/18/2016] [Indexed: 01/13/2023] Open
Abstract
It is unclear how genes, such as RPGR (retinitis pigmentosa guanine triphosphatase regulator) that are expressed in both rods and cones, cause variable disease pathogenesis. Using transcriptomic analysis, we show that loss of RPGR in a rod-dominant mouse retina (Rpgr(ko)) results in predominant alterations in genes involved in actin cytoskeletal dynamics, prior to onset of degeneration. We validated these findings and found an increase in activated RhoA-GTP levels and polymerized F-actin in the Rpgr(ko) mouse retina. To assess the effect of the loss of RPGR in the all-cone region of the human retina, we used Nrl(-/-) (neural retina leucine zipper) mice, to generate Rpgr(ko)::Nrl(-/-) double-knock-out (Rpgr-DKO) mice. These mice exhibited supranormal cone response to light and substantially retained retinal architecture. Transcriptomic analysis revealed predominant up-regulation of retinal pigmented epithelium (RPE)-specific genes associated with visual cycle, whereas fatty acid analysis showed mild decrease in docosahexaenoic acid in the retina of the Rpgr-DKO mice when compared with the Nrl(-/-) mice. Our data reveal new insights into distinct intracellular pathways that are involved in RPGR-associated rod and cone dysfunction and provide a platform to design new treatment modalities.
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Affiliation(s)
- Kollu N Rao
- Department of Ophthalmology, University of Massachusetts Medical School, 368 Plantation St, Albert Sherman Center AS6-2043, Worcester, MA 01605, USA and
| | - Linjing Li
- Department of Ophthalmology, University of Massachusetts Medical School, 368 Plantation St, Albert Sherman Center AS6-2043, Worcester, MA 01605, USA and
| | - Wei Zhang
- Department of Ophthalmology, University of Massachusetts Medical School, 368 Plantation St, Albert Sherman Center AS6-2043, Worcester, MA 01605, USA and
| | - Richard S Brush
- University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Raju V S Rajala
- University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Hemant Khanna
- Department of Ophthalmology, University of Massachusetts Medical School, 368 Plantation St, Albert Sherman Center AS6-2043, Worcester, MA 01605, USA and
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226
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Laprell L, Hüll K, Stawski P, Schön C, Michalakis S, Biel M, Sumser MP, Trauner D. Restoring Light Sensitivity in Blind Retinae Using a Photochromic AMPA Receptor Agonist. ACS Chem Neurosci 2016; 7:15-20. [PMID: 26495755 PMCID: PMC4722500 DOI: 10.1021/acschemneuro.5b00234] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 10/23/2015] [Indexed: 12/15/2022] Open
Abstract
Retinal degenerative diseases can have many possible causes and are currently difficult to treat. As an alternative to therapies that require genetic manipulation or the implantation of electronic devices, photopharmacology has emerged as a viable approach to restore visual responses. Here, we present a new photopharmacological strategy that relies on a photoswitchable excitatory amino acid, ATA. This freely diffusible molecule selectively activates AMPA receptors in a light-dependent fashion. It primarily acts on amacrine and retinal ganglion cells, although a minor effect on bipolar cells has been observed. As such, it complements previous pharmacological approaches based on photochromic channel blockers and increases the potential of photopharmacology in vision restoration.
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Affiliation(s)
- L. Laprell
- Center
of Integrated Protein Science Munich (CIPSM) at the Department of
Chemistry Ludwig-Maximilians-Universität
München, Munich 81377, Germany
| | - K. Hüll
- Center
of Integrated Protein Science Munich (CIPSM) at the Department of
Chemistry Ludwig-Maximilians-Universität
München, Munich 81377, Germany
| | - P. Stawski
- Center
of Integrated Protein Science Munich (CIPSM) at the Department of
Chemistry Ludwig-Maximilians-Universität
München, Munich 81377, Germany
| | - C. Schön
- Center
for Integrated Protein Science Munich (CIPSM) at the Department of
Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität
München, Munich 81377, Germany
| | - S. Michalakis
- Center
for Integrated Protein Science Munich (CIPSM) at the Department of
Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität
München, Munich 81377, Germany
| | - M Biel
- Center
for Integrated Protein Science Munich (CIPSM) at the Department of
Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität
München, Munich 81377, Germany
| | - M. P. Sumser
- Center
of Integrated Protein Science Munich (CIPSM) at the Department of
Chemistry Ludwig-Maximilians-Universität
München, Munich 81377, Germany
| | - D. Trauner
- Center
of Integrated Protein Science Munich (CIPSM) at the Department of
Chemistry Ludwig-Maximilians-Universität
München, Munich 81377, Germany
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227
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Hasegawa T, Ikeda HO, Nakano N, Muraoka Y, Tsuruyama T, Okamoto-Furuta K, Kohda H, Yoshimura N. Changes in morphology and visual function over time in mouse models of retinal degeneration: an SD-OCT, histology, and electroretinography study. Jpn J Ophthalmol 2016; 60:111-25. [PMID: 26729343 DOI: 10.1007/s10384-015-0422-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 11/12/2015] [Indexed: 11/30/2022]
Abstract
PURPOSE To examine the long-term natural course of retinal degeneration in rd10 and rd12 mice using serial spectral-domain optical coherence tomography (SD-OCT), electroretinography/electroretinograms (ERGs), and histological analysis. METHODS Photoreceptor layer thickness and the ability to visualize photoreceptor ellipsoid zones were analyzed using SD-OCT images, and these images were compared with hematoxylin and eosin-stained sections and electron microscopy images. The a- and b-wave amplitudes of the ERGs were analyzed. RESULTS In rd10 mice, the photoreceptor layer thickness rapidly decreased, and the photoreceptor ellipsoid zone was visible on SD-OCT images in 89 and 43 % of eyes of 21 and 33-day-old mice, respectively. In rd12 mice, the photoreceptor layer gradually thinned, and the ellipsoid zone remained visible in 92 % of eyes at 19 months. Electron microscopy revealed that photoreceptor degeneration had occurred on the inner side of the outer nuclear layer in 21-day-old rd10 and 7-month-old rd12 mice, possibly due to autophagy mechanisms. Scotopic ERGs of rd10 mice showed a diminished response at 21 days; at 33 days, no response was detectable. In rd12 mice, scotopic ERGs were undetectable at 28 days (stimulus intensity 3.0 cds/m(2)). Photopic ERGs were nearly undetectable in 28-day-old rd10 mice, but a small b-wave was still recordable in 13-month-old rd12 mice. CONCLUSIONS Our results demonstrate that visual function deteriorated with photoreceptor degeneration within 1 month in rd10 mice. In rd12 mice, however, the process of visual function deterioration and photoreceptor degeneration was still in progress at 13 months of age.
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Affiliation(s)
- Tomoko Hasegawa
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, 54 Kawahara-cho Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan
| | - Hanako O Ikeda
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, 54 Kawahara-cho Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan. .,Institute for Advancement of Clinical and Translational Science, Kyoto University Hospital, Kyoto, Japan.
| | - Noriko Nakano
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, 54 Kawahara-cho Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan
| | - Yuki Muraoka
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, 54 Kawahara-cho Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan
| | - Tatsuaki Tsuruyama
- Center for Anatomical Studies, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Keiko Okamoto-Furuta
- Center for Anatomical Studies, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Haruyasu Kohda
- Center for Anatomical Studies, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Nagahisa Yoshimura
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, 54 Kawahara-cho Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan
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228
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The Consequences of Hypomorphic RPE65 for Rod and Cone Photoreceptors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 854:341-6. [PMID: 26427430 DOI: 10.1007/978-3-319-17121-0_45] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
RPE65 is essential for both rod- and cone-mediated vision. So far, more than 120 disease-associated mutations have been identified in the human RPE65 gene. Differential clinical manifestations suggested that some patients suffer from null mutations while others retain residual RPE65 activity and some useful vision. To understand the mechanism of retinal degeneration or dysfunction caused by such hypomorphic RPE65 alleles, we generated an Rpe65 (R91W) knock-in mouse (R91W) that expresses a mutant RPE65 protein with reduced function. Data obtained suggested that the R91W mouse is highly suitable to study the impact of RPE65 insufficiency on rod pathophysiology. To study the impact on cones, we combined the R91W with the Nrl (-/-) mouse that develops an all-cone retina. Here we summarize the consequences of hypomorphic RPE65 function (reduced 11-cis-retinal synthesis) for rod and cone pathophysiology.
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229
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Abstract
Age-related macular degeneration (AMD), the most common form of irreversible blindness in the industrially developed world, can present years before a patient begins to lose vision. For most of these patients, AMD never progresses past its early stages to the advanced forms that are principally responsible for the vast majority of vision loss. Advanced AMD can manifest as either an advanced avascular form known as geographic atrophy (GA) marked by regional retinal pigment epithelium (RPE) cell death or as an advanced form known as neovascular AMD marked by the intrusion of fragile new blood vessels into the normally avascular retina. Physicians have several therapeutic interventions available to combat neovascular AMD, but GA has no approved effective therapies as of yet. In this chapter, we will discuss the current strategies for limiting dry AMD in patients. We will also discuss previous attempts at pharmacological intervention that were tested in a clinical setting and consider reasons why these putative therapeutics did not perform successfully in large-scale trials. Despite the number of unsuccessful past trials, new pharmacological interventions may succeed. These future therapies may aid millions of AMD patients worldwide.
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Affiliation(s)
- Charles B Wright
- Physiology and Ophthalmology and Visual Sciences, University of Kentucky College of Medicine, Lexington, KY, 40506, USA
| | - Jayakrishna Ambati
- Physiology and Ophthalmology and Visual Sciences, University of Kentucky College of Medicine, Lexington, KY, 40506, USA.
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230
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Stiles M, Moiseyev GP, Budda ML, Linens A, Brush RS, Qi H, White GL, Wolf RF, Ma JX, Floyd R, Anderson RE, Mandal NA. PBN (Phenyl-N-Tert-Butylnitrone)-Derivatives Are Effective in Slowing the Visual Cycle and Rhodopsin Regeneration and in Protecting the Retina from Light-Induced Damage. PLoS One 2015; 10:e0145305. [PMID: 26694648 PMCID: PMC4687940 DOI: 10.1371/journal.pone.0145305] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 12/02/2015] [Indexed: 11/18/2022] Open
Abstract
A2E and related toxic molecules are part of lipofuscin found in the retinal pigment epithelial (RPE) cells in eyes affected by Stargardt's disease, age-related macular degeneration (AMD), and other retinal degenerations. A novel therapeutic approach for treating such degenerations involves slowing down the visual cycle, which could reduce the amount of A2E in the RPE. This can be accomplished by inhibiting RPE65, which produces 11-cis-retinol from all-trans-retinyl esters. We recently showed that phenyl-N-tert-butylnitrone (PBN) inhibits RPE65 enzyme activity in RPE cells. In this study we show that like PBN, certain PBN-derivatives (PBNDs) such as 4-F-PBN, 4-CF3-PBN, 3,4-di-F-PBN, and 4-CH3-PBN can inhibit RPE65 and synthesis of 11-cis-retinol in in vitro assays using bovine RPE microsomes. We further demonstrate that systemic (intraperitoneal, IP) administration of these PBNDs protect the rat retina from light damage. Electroretinography (ERG) and histological analysis showed that rats treated with PBNDs retained ~90% of their photoreceptor cells compared to a complete loss of function and 90% loss of photoreceptors in the central retina in rats treated with vehicle/control injections. Topically applied PBN and PBNDs also significantly slowed the rate of the visual cycle in mouse and baboon eyes. One hour dark adaptation resulted in 75-80% recovery of bleachable rhodopsin in control/vehicle treated mice. Eye drops of 5% 4-CH3-PBN were most effective, inhibiting the regeneration of bleachable rhodopsin significantly (60% compared to vehicle control). In addition, a 10% concentration of PBN and 5% concentration of 4-CH3-PBN in baboon eyes inhibited the visual cycle by 60% and by 30%, respectively. We have identified a group of PBN related nitrones that can reach the target tissue (RPE) by systemic and topical application and slow the rate of rhodopsin regeneration and therefore the visual cycle in mouse and baboon eyes. PBNDs can also protect the rat retina from light damage. There is potential in developing these compounds as preventative therapeutics for the treatment of human retinal degenerations in which the accumulation of lipofuscin may be pathogenic.
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Affiliation(s)
- Megan Stiles
- Department of Ophthalmology, OUHSC, Oklahoma City, Oklahoma, United States of America
- Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States of America
| | - Gennadiy P. Moiseyev
- Department of Physiology, OUHSC, Oklahoma City, Oklahoma, United States of America
| | - Madeline L. Budda
- Department of Cell Biology, OUHSC, Oklahoma City, Oklahoma, United States of America
| | - Annette Linens
- Department of Ophthalmology, OUHSC, Oklahoma City, Oklahoma, United States of America
- Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States of America
| | - Richard S. Brush
- Department of Ophthalmology, OUHSC, Oklahoma City, Oklahoma, United States of America
- Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States of America
| | - Hui Qi
- Department of Ophthalmology, OUHSC, Oklahoma City, Oklahoma, United States of America
- Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States of America
| | - Gary L. White
- Department of Pathology, OUHSC, Oklahoma City, Oklahoma, United States of America
| | - Roman F. Wolf
- Department of Pathology, OUHSC, Oklahoma City, Oklahoma, United States of America
| | - Jian-xing Ma
- Department of Physiology, OUHSC, Oklahoma City, Oklahoma, United States of America
- Department of Endocrinology and Diabetes, OUHSC, Oklahoma City, Oklahoma, United States of America
| | - Robert Floyd
- Experimental Therapeutics, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, United States of America
| | - Robert E. Anderson
- Department of Ophthalmology, OUHSC, Oklahoma City, Oklahoma, United States of America
- Department of Pathology, OUHSC, Oklahoma City, Oklahoma, United States of America
- Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States of America
| | - Nawajes A. Mandal
- Department of Ophthalmology, OUHSC, Oklahoma City, Oklahoma, United States of America
- Department of Cell Biology, OUHSC, Oklahoma City, Oklahoma, United States of America
- Department of Endocrinology and Diabetes, OUHSC, Oklahoma City, Oklahoma, United States of America
- Oklahoma Center for Neuroscience, OUHSC, Oklahoma City, Oklahoma, United States of America
- Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States of America
- * E-mail:
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231
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Scholl HPN, Moore AT, Koenekoop RK, Wen Y, Fishman GA, van den Born LI, Bittner A, Bowles K, Fletcher EC, Collison FT, Dagnelie G, Degli Eposti S, Michaelides M, Saperstein DA, Schuchard RA, Barnes C, Zein W, Zobor D, Birch DG, Mendola JD, Zrenner E. Safety and Proof-of-Concept Study of Oral QLT091001 in Retinitis Pigmentosa Due to Inherited Deficiencies of Retinal Pigment Epithelial 65 Protein (RPE65) or Lecithin:Retinol Acyltransferase (LRAT). PLoS One 2015; 10:e0143846. [PMID: 26656277 PMCID: PMC4687523 DOI: 10.1371/journal.pone.0143846] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 10/29/2015] [Indexed: 11/30/2022] Open
Abstract
Restoring vision in inherited retinal degenerations remains an unmet medical need. In mice exhibiting a genetically engineered block of the visual cycle, vision was recently successfully restored by oral administration of 9-cis-retinyl acetate (QLT091001). Safety and visual outcomes of a once-daily oral dose of 40 mg/m2/day QLT091001 for 7 consecutive days was investigated in an international, multi-center, open-label, proof-of-concept study in 18 patients with RPE65- or LRAT-related retinitis pigmentosa. Eight of 18 patients (44%) showed a ≥20% increase and 4 of 18 (22%) showed a ≥40% increase in functional retinal area determined from Goldmann visual fields; 12 (67%) and 5 (28%) of 18 patients showed a ≥5 and ≥10 ETDRS letter score increase of visual acuity, respectively, in one or both eyes at two or more visits within 2 months of treatment. In two patients who underwent fMRI, a significant positive response was measured to stimuli of medium contrast, moving, pattern targets in both left and right hemispheres of the occipital cortex. There were no serious adverse events. Treatment-related adverse events were transient and the most common included headache, photophobia, nausea, vomiting, and minor biochemical abnormalities. Measuring the outer segment length of the photoreceptor layer with high-definition optical coherence tomography was highly predictive of treatment responses with responders having a significantly larger baseline outer segment thickness (11.7 ± 4.8 μm, mean ± 95% CI) than non-responders (3.5 ± 1.2 μm). This structure-function relationship suggests that treatment with QLT091001 is more likely to be efficacious if there is sufficient photoreceptor integrity.
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Affiliation(s)
- Hendrik P. N. Scholl
- Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, United States of America
- * E-mail:
| | - Anthony T. Moore
- Moorfields Eye Hospital and Institute of Ophthalmology, University College London, London, United Kingdom
- Dept. of Ophthalmology, University of California San Francisco, San Francisco, CA, United States of America
| | | | - Yuquan Wen
- Retina Foundation of the Southwest, Dallas, TX, United States of America
- Baylor Visual Function Center, Baylor University Medical Center, Dallas, TX, United States of America
| | - Gerald A. Fishman
- Chicago Lighthouse, Pangere Center for Inherited Retinal Diseases, Chicago, IL, United States of America
| | | | - Ava Bittner
- Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, United States of America
- Nova Southeastern University, College of Optometry, Fort Lauderdale, FL, United States of America
| | - Kristen Bowles
- Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, United States of America
- College of Optometry, University of Houston, Houston, TX, United States of America
| | - Emily C. Fletcher
- Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, United States of America
- Gloucester Royal NHS Foundation Trust, Gloucester Royal Hospitals, Gloucester, United Kingdom
| | - Frederick T. Collison
- Chicago Lighthouse, Pangere Center for Inherited Retinal Diseases, Chicago, IL, United States of America
| | - Gislin Dagnelie
- Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, United States of America
| | - Simona Degli Eposti
- Moorfields Eye Hospital and Institute of Ophthalmology, University College London, London, United Kingdom
| | - Michel Michaelides
- Moorfields Eye Hospital and Institute of Ophthalmology, University College London, London, United Kingdom
| | - David A. Saperstein
- Vitreoretinal Associates of Washington, Seattle, WA, United States of America
- QLT Inc., Vancouver, Canada
| | - Ronald A. Schuchard
- QLT Inc., Vancouver, Canada
- Stanford Univ School of Medicine, Palo Alto, CA, United States of America
| | - Claire Barnes
- QLT Inc., Vancouver, Canada
- VA Palo Alto Health Care System, Palo Alto, CA, United States of America
| | - Wadih Zein
- Division of Epidemiology and Clinical Research, National Eye Institute, National Institutes of Health, Bethesda, MD, United States of America
| | - Ditta Zobor
- Institute for Ophthalmic Research, Center for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - David G. Birch
- Retina Foundation of the Southwest, Dallas, TX, United States of America
- Ophthalmology, UT Southwestern, Dallas, TX, United States of America
| | | | - Eberhart Zrenner
- Institute for Ophthalmic Research, Center for Ophthalmology, University of Tübingen, Tübingen, Germany
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232
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Tucker BA, Cranston CM, Anfinson KA, Shrestha S, Streb LM, Leon A, Mullins RF, Stone EM. Using patient-specific induced pluripotent stem cells to interrogate the pathogenicity of a novel retinal pigment epithelium-specific 65 kDa cryptic splice site mutation and confirm eligibility for enrollment into a clinical gene augmentation trial. Transl Res 2015; 166:740-749.e1. [PMID: 26364624 PMCID: PMC4702513 DOI: 10.1016/j.trsl.2015.08.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 08/18/2015] [Accepted: 08/24/2015] [Indexed: 01/07/2023]
Abstract
Retinal pigment epithelium-specific 65 kDa (RPE65)-associated Leber congenital amaurosis is an autosomal recessive disease that results in reduced visual acuity and night blindness beginning at birth. It is one of the few retinal degenerative disorders for which promising clinical gene transfer trials are currently underway. However, the ability to enroll patients in a gene augmentation trial is dependent on the identification of 2 bona fide disease-causing mutations, and there are some patients with the phenotype of RPE65-associated disease who might benefit from gene transfer but are ineligible because 2 disease-causing genetic variations have not yet been identified. Some such patients have novel mutations in RPE65 for which pathogenicity is difficult to confirm. The goal of this study was to determine if an intronic mutation identified in a 2-year-old patient with presumed RPE65-associated disease was truly pathogenic and grounds for inclusion in a clinical gene augmentation trial. Sequencing of the RPE65 gene revealed 2 mutations: (1) a previously identified disease-causing exonic leucine-to-proline mutation (L408P) and (2) a novel single point mutation in intron 3 (IVS3-11) resulting in an A>G change. RT-PCR analysis using RNA extracted from control human donor eye-derived primary RPE, control iPSC-RPE cells, and proband iPSC-RPE cells revealed that the identified IVS3-11 variation caused a splicing defect that resulted in a frameshift and insertion of a premature stop codon. In this study, we demonstrate how patient-specific iPSCs can be used to confirm pathogenicity of unknown mutations, which can enable positive clinical outcomes.
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Affiliation(s)
- Budd A Tucker
- Stephen A Wynn Institute for Vision Research, Department of Ophthalmology and Visual Science, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Cathryn M Cranston
- Stephen A Wynn Institute for Vision Research, Department of Ophthalmology and Visual Science, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Kristin A Anfinson
- Stephen A Wynn Institute for Vision Research, Department of Ophthalmology and Visual Science, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Suruchi Shrestha
- Stephen A Wynn Institute for Vision Research, Department of Ophthalmology and Visual Science, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Luan M Streb
- Stephen A Wynn Institute for Vision Research, Department of Ophthalmology and Visual Science, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Alejandro Leon
- Department of Ophthalmology, Children's Hospital New Orleans, New Orleans, La
| | - Robert F Mullins
- Stephen A Wynn Institute for Vision Research, Department of Ophthalmology and Visual Science, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Edwin M Stone
- Stephen A Wynn Institute for Vision Research, Department of Ophthalmology and Visual Science, Carver College of Medicine, University of Iowa, Iowa City, Iowa; Howard Hughes Medical Institute, Department of Ophthalmology and Visual Science, University of Iowa, Iowa City, Iowa.
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233
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Kostic C, Arsenijevic Y. Animal modelling for inherited central vision loss. J Pathol 2015; 238:300-10. [PMID: 26387748 PMCID: PMC5063185 DOI: 10.1002/path.4641] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 09/02/2015] [Accepted: 09/16/2015] [Indexed: 01/01/2023]
Abstract
Disease-causing variants of a large number of genes trigger inherited retinal degeneration leading to photoreceptor loss. Because cones are essential for daylight and central vision such as reading, mobility, and face recognition, this review focuses on a variety of animal models for cone diseases. The pertinence of using these models to reveal genotype/phenotype correlations and to evaluate new therapeutic strategies is discussed. Interestingly, several large animal models recapitulate human diseases and can serve as a strong base from which to study the biology of disease and to assess the scale-up of new therapies. Examples of innovative approaches will be presented such as lentiviral-based transgenesis in pigs and adeno-associated virus (AAV)-gene transfer into the monkey eye to investigate the neural circuitry plasticity of the visual system. The models reported herein permit the exploration of common mechanisms that exist between different species and the identification and highlighting of pathways that may be specific to primates, including humans.
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Affiliation(s)
- Corinne Kostic
- Unit of Gene Therapy and Stem Cell Biology, Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, University of Lausanne, Switzerland
| | - Yvan Arsenijevic
- Unit of Gene Therapy and Stem Cell Biology, Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, University of Lausanne, Switzerland
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234
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Furukawa A, Koriyama Y. A role of Heat Shock Protein 70 in Photoreceptor Cell Death: Potential as a Novel Therapeutic Target in Retinal Degeneration. CNS Neurosci Ther 2015; 22:7-14. [PMID: 26507240 DOI: 10.1111/cns.12471] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 09/23/2015] [Accepted: 09/25/2015] [Indexed: 01/17/2023] Open
Abstract
Retinal degenerative diseases (RDs) such as retinitis pigmentosa (RP) are a genetically heterogeneous group of disorders characterized by night blindness and peripheral vision loss, which caused by the dysfunction and death of photoreceptor cells. Although many causative gene mutations have been reported, the final common end stage is photoreceptor cell death. Unfortunately, no effective treatments or therapeutic agents have been discovered. Heat shock protein 70 (HSP70) is highly conserved and has antiapoptotic activities. A few reports have shown that HSP70 plays a role in RDs. Thus, we focused on the role of HSP70 in photoreceptor cell death. Using the N-methyl-N-nitrosourea (MNU)-induced photoreceptor cell death model in mice, we could examine two stages of the novel cell death mechanism; the early stage, including HSP70 cleavage through protein carbonylation by production of reactive oxygen species, lipid peroxidation and Ca(2+) influx/calpain activation, and the late stage of cathepsin and/or caspase activation. The upregulation of intact HSP70 expression by its inducer is likely to protect photoreceptor cells. In this review, we focus on the role of HSP70 and the novel cell death signaling process in RDs. We also describe candidate therapeutic agents for RDs.
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Affiliation(s)
- Ayako Furukawa
- Graduate School and Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan
| | - Yoshiki Koriyama
- Graduate School and Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka, Japan
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235
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Veleri S, Lazar CH, Chang B, Sieving PA, Banin E, Swaroop A. Biology and therapy of inherited retinal degenerative disease: insights from mouse models. Dis Model Mech 2015; 8:109-29. [PMID: 25650393 PMCID: PMC4314777 DOI: 10.1242/dmm.017913] [Citation(s) in RCA: 179] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Retinal neurodegeneration associated with the dysfunction or death of photoreceptors is a major cause of incurable vision loss. Tremendous progress has been made over the last two decades in discovering genes and genetic defects that lead to retinal diseases. The primary focus has now shifted to uncovering disease mechanisms and designing treatment strategies, especially inspired by the successful application of gene therapy in some forms of congenital blindness in humans. Both spontaneous and laboratory-generated mouse mutants have been valuable for providing fundamental insights into normal retinal development and for deciphering disease pathology. Here, we provide a review of mouse models of human retinal degeneration, with a primary focus on diseases affecting photoreceptor function. We also describe models associated with retinal pigment epithelium dysfunction or synaptic abnormalities. Furthermore, we highlight the crucial role of mouse models in elucidating retinal and photoreceptor biology in health and disease, and in the assessment of novel therapeutic modalities, including gene- and stem-cell-based therapies, for retinal degenerative diseases.
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Affiliation(s)
- Shobi Veleri
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Csilla H Lazar
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA. Molecular Biology Center, Interdisciplinary Research Institute on Bio-Nano Sciences, Babes-Bolyai-University, Cluj-Napoca, 400271, Romania
| | - Bo Chang
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | - Paul A Sieving
- National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Eyal Banin
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA. Center for Retinal and Macular Degenerations, Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem 91120, Israel
| | - Anand Swaroop
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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236
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Sahu B, Sun W, Perusek L, Parmar V, Le YZ, Griswold MD, Palczewski K, Maeda A. Conditional Ablation of Retinol Dehydrogenase 10 in the Retinal Pigmented Epithelium Causes Delayed Dark Adaption in Mice. J Biol Chem 2015; 290:27239-27247. [PMID: 26391396 DOI: 10.1074/jbc.m115.682096] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Indexed: 12/29/2022] Open
Abstract
Regeneration of the visual chromophore, 11-cis-retinal, is a crucial step in the visual cycle required to sustain vision. This cycle consists of sequential biochemical reactions that occur in photoreceptor cells and the retinal pigmented epithelium (RPE). Oxidation of 11-cis-retinol to 11-cis-retinal is accomplished by a family of enzymes termed 11-cis-retinol dehydrogenases, including RDH5 and RDH11. Double deletion of Rdh5 and Rdh11 does not limit the production of 11-cis-retinal in mice. Here we describe a third retinol dehydrogenase in the RPE, RDH10, which can produce 11-cis-retinal. Mice with a conditional knock-out of Rdh10 in RPE cells (Rdh10 cKO) displayed delayed 11-cis-retinal regeneration and dark adaption after bright light illumination. Retinal function measured by electroretinogram after light exposure was also delayed in Rdh10 cKO mice as compared with controls. Double deletion of Rdh5 and Rdh10 (cDKO) in mice caused elevated 11/13-cis-retinyl ester content also seen in Rdh5(-/-)Rdh11(-/-) mice as compared with Rdh5(-/-) mice. Normal retinal morphology was observed in 6-month-old Rdh10 cKO and cDKO mice, suggesting that loss of Rdh10 in the RPE does not negatively affect the health of the retina. Compensatory expression of other retinol dehydrogenases was observed in both Rdh5(-/-) and Rdh10 cKO mice. These results indicate that RDH10 acts in cooperation with other RDH isoforms to produce the 11-cis-retinal chromophore needed for vision.
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Affiliation(s)
- Bhubanananda Sahu
- Departments of Ophthalmology and Visual Sciences, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106
| | - Wenyu Sun
- Polgenix, Inc., Cleveland, Ohio 44106
| | - Lindsay Perusek
- Departments of Ophthalmology and Visual Sciences, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106
| | - Vipulkumar Parmar
- Departments of Ophthalmology and Visual Sciences, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106
| | - Yun-Zheng Le
- Departments of Medicine Endocrinology, Cell Biology, and Ophthalmology and the Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Michael D Griswold
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164
| | - Krzysztof Palczewski
- Departments of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106; Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106
| | - Akiko Maeda
- Departments of Ophthalmology and Visual Sciences, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106; Departments of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106.
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237
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Abstract
Recent gene therapy progress has raised the possibility that vision loss caused by inherited retinal degeneration can be slowed or prevented. Unfortunately, patients are not usually diagnosed until enough degeneration has occurred that the deterioration in vision is noticeable. Therefore, effective gene therapy must halt degeneration to stabilize and preserve any remaining vision. Gene therapy methods currently in human clinical trials rely on subretinal or intravitreal injections of adeno-associated virus to deliver the therapeutic gene. To date, long-term results in patients treated with subretinal injections for Leber congenital amaurosis have been mixed. Proposed limitations include variability in the gene delivery method and a possible point of no return, at which treatment would be ineffective. In this issue of the JCI, Koch et al. describe a well-controlled and precise mouse model for testing the ability of gene therapy to halt the progress of degeneration. Instead of viral-mediated therapeutic gene delivery, the authors induced expression of an integrated transgene at specific times during the course of photoreceptor degeneration. In Pde6b-deficient retina, this strategy halted degeneration, even when more than 70% of photoreceptors had already degenerated. The results of this study demonstrate that retinal degeneration can be stopped, even at late stages of disease.
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238
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Vinberg F, Wang T, Molday RS, Chen J, Kefalov VJ. A new mouse model for stationary night blindness with mutant Slc24a1 explains the pathophysiology of the associated human disease. Hum Mol Genet 2015; 24:5915-29. [PMID: 26246500 DOI: 10.1093/hmg/ddv319] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 07/31/2015] [Indexed: 11/12/2022] Open
Abstract
Mutations that affect calcium homeostasis (Ca(2+)) in rod photoreceptors are linked to retinal degeneration and visual disorders such as retinitis pigmentosa and congenital stationary night blindness (CSNB). It is thought that the concentration of Ca(2+) in rod outer segments is controlled by a dynamic balance between influx via cGMP-gated (CNG) channels and extrusion via Na(+)/Ca(2+), K(+) exchangers (NCKX1). The extrusion-driven lowering of rod [Ca(2+)]i following light exposure controls their light adaptation and response termination. Mutant NCKX1 has been linked to autosomal-recessive stationary night blindness. However, whether NCKX1 contributes to light adaptation has not been directly tested and the mechanisms by which human NCKX1 mutations cause night blindness are not understood. Here, we report that the deletion of NCKX1 in mice results in malformed outer segment disks, suppressed expression and function of rod CNG channels and a subsequent 100-fold reduction in rod responses, while preserving normal cone responses. The compensating loss of CNG channel function in the absence of NCKX1-mediated Ca(2+) extrusion may prevent toxic Ca(2+) buildup and provides an explanation for the stationary nature of the associated disorder in humans. Surprisingly, the lack of NCKX1 did not compromise rod background light adaptation, suggesting additional Ca(2+)-extruding mechanisms exist in these cells.
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Affiliation(s)
- Frans Vinberg
- Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO, USA
| | - Tian Wang
- Cell and Neurobiology, Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, CA, USA and
| | - Robert S Molday
- Biochemistry/Molecular Biology, University of British Columbia, Vancouver, Canada
| | - Jeannie Chen
- Cell and Neurobiology, Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, CA, USA and
| | - Vladimir J Kefalov
- Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO, USA,
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239
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Abstract
Cones are photoreceptor cells used for bright light and color vision. Retinoids are vitamin A derivatives, one of which is the 11-cis aldehyde form that serves as the chromophore for both cone and rod visual pigments. In the visual disease, Type 2 Leber congenital amaurosis (LCA2), 11-cis-retinal generation is inhibited or abolished. Work by others has shown that patients with LCA2 have symptoms consistent with degenerating cones. In mouse models for LCA2, early cone degeneration is readily apparent: cone opsins and other proteins associated with the outer segment are delocalized and cell numbers decline rapidly within the first month. Rods would appear normal morphologically and functionally, if not for the absence of chromophore. Supplementation of mouse models of LCA2 with cis-retinoids has been shown to slow loss of cone photoreceptor cells if mice were maintained in darkness. Thus, 11-cis-retinal appears not only to have a role in the light response reaction but also to promote proper trafficking of the cone opsins and maintain viable cones.
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Affiliation(s)
- Masahiro Kono
- Department of Ophthalmology, Albert Florens Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA.
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240
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Wang Y, Rajala A, Rajala RVS. Lipid Nanoparticles for Ocular Gene Delivery. J Funct Biomater 2015; 6:379-94. [PMID: 26062170 PMCID: PMC4493518 DOI: 10.3390/jfb6020379] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 06/01/2015] [Accepted: 06/02/2015] [Indexed: 02/07/2023] Open
Abstract
Lipids contain hydrocarbons and are the building blocks of cells. Lipids can naturally form themselves into nano-films and nano-structures, micelles, reverse micelles, and liposomes. Micelles or reverse micelles are monolayer structures, whereas liposomes are bilayer structures. Liposomes have been recognized as carriers for drug delivery. Solid lipid nanoparticles and lipoplex (liposome-polycation-DNA complex), also called lipid nanoparticles, are currently used to deliver drugs and genes to ocular tissues. A solid lipid nanoparticle (SLN) is typically spherical, and possesses a solid lipid core matrix that can solubilize lipophilic molecules. The lipid nanoparticle, called the liposome protamine/DNA lipoplex (LPD), is electrostatically assembled from cationic liposomes and an anionic protamine-DNA complex. The LPD nanoparticles contain a highly condensed DNA core surrounded by lipid bilayers. SLNs are extensively used to deliver drugs to the cornea. LPD nanoparticles are used to target the retina. Age-related macular degeneration, retinitis pigmentosa, and diabetic retinopathy are the most common retinal diseases in humans. There have also been promising results achieved recently with LPD nanoparticles to deliver functional genes and micro RNA to treat retinal diseases. Here, we review recent advances in ocular drug and gene delivery employing lipid nanoparticles.
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Affiliation(s)
- Yuhong Wang
- Dean A. McGee Eye Institute, Oklahoma City, OK 73104, USA.
- Department of Ophthalmology, College of Medicine, University of Oklahoma, Oklahoma City, OK 73014, USA.
| | - Ammaji Rajala
- Dean A. McGee Eye Institute, Oklahoma City, OK 73104, USA.
- Department of Ophthalmology, College of Medicine, University of Oklahoma, Oklahoma City, OK 73014, USA.
| | - Raju V S Rajala
- Dean A. McGee Eye Institute, Oklahoma City, OK 73104, USA.
- Department of Ophthalmology, College of Medicine, University of Oklahoma, Oklahoma City, OK 73014, USA.
- Department of Physiology and Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73014, USA.
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241
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Bainbridge JWB, Mehat MS, Sundaram V, Robbie SJ, Barker SE, Ripamonti C, Georgiadis A, Mowat FM, Beattie SG, Gardner PJ, Feathers KL, Luong VA, Yzer S, Balaggan K, Viswanathan A, de Ravel TJL, Casteels I, Holder GE, Tyler N, Fitzke FW, Weleber RG, Nardini M, Moore AT, Thompson DA, Petersen-Jones SM, Michaelides M, van den Born LI, Stockman A, Smith AJ, Rubin G, Ali RR. Long-term effect of gene therapy on Leber's congenital amaurosis. N Engl J Med 2015; 372:1887-97. [PMID: 25938638 PMCID: PMC4497809 DOI: 10.1056/nejmoa1414221] [Citation(s) in RCA: 530] [Impact Index Per Article: 58.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
BACKGROUND Mutations in RPE65 cause Leber's congenital amaurosis, a progressive retinal degenerative disease that severely impairs sight in children. Gene therapy can result in modest improvements in night vision, but knowledge of its efficacy in humans is limited. METHODS We performed a phase 1-2 open-label trial involving 12 participants to evaluate the safety and efficacy of gene therapy with a recombinant adeno-associated virus 2/2 (rAAV2/2) vector carrying the RPE65 complementary DNA, and measured visual function over the course of 3 years. Four participants were administered a lower dose of the vector, and 8 were administered a higher dose. In a parallel study in dogs, we investigated the relationship among vector dose, visual function, and electroretinography (ERG) findings. RESULTS Improvements in retinal sensitivity were evident, to varying extents, in six participants for up to 3 years, peaking at 6 to 12 months after treatment and then declining. No associated improvement in retinal function was detected by means of ERG. Three participants had intraocular inflammation, and two had clinically significant deterioration of visual acuity. The reduction in central retinal thickness varied among participants. In dogs, RPE65 gene therapy with the same vector at lower doses improved vision-guided behavior, but only higher doses resulted in improvements in retinal function that were detectable with the use of ERG. CONCLUSIONS Gene therapy with rAAV2/2 RPE65 vector improved retinal sensitivity, albeit modestly and temporarily. Comparison with the results obtained in the dog model indicates that there is a species difference in the amount of RPE65 required to drive the visual cycle and that the demand for RPE65 in affected persons was not met to the extent required for a durable, robust effect. (Funded by the National Institute for Health Research and others; ClinicalTrials.gov number, NCT00643747.).
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Affiliation(s)
- James W B Bainbridge
- From the UCL (University College London) Institute of Ophthalmology (J.W.B.B., M.S.M., V.S., S.J.R., S.E.B., C.R., A.G., F.M.M., S.G.B., P.J.G., V.A.L., K.B., A.V., G.E.H., F.W.F., M.N., A.T.M., M.M., A.S., A.J.S., G.R., R.R.A.) and the Department of Civil, Environmental, and Geomatic Engineering (N.T.), UCL, and Moorfields Eye Hospital (J.W.B.B., M.S.M., V.S., S.J.R., A.G., K.B., G.H., A.M., M.M.), London, and the Department of Psychology, Durham University, Durham (M.N.) - all in the United Kingdom; the College of Veterinary Medicine, Michigan State University, East Lansing (F.M.M., S.M.P.-J.), and the Kellogg Eye Center, University of Michigan Medical School, Ann Arbor (K.L.F., D.A.T., R.R.A.); the Center for Human Genetics, KU Leuven (T.J.L.R.), and the Department of Ophthalmology, UZ Leuven, Campus Sint-Rafaël (I.C.) - both in Leuven, Belgium; Rotterdam Eye Hospital, Rotterdam, the Netherlands (S.Y., L.I.B.); and the Oregon Retinal Degeneration Center, Ophthalmic Genetics Service, Casey Eye Institute, Oregon Health and Science University, Portland (R.G.W.)
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242
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Affiliation(s)
- Alan F Wright
- From the MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh
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243
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Li Y, Yu S, Duncan T, Li Y, Liu P, Gene E, Cortes-Pena Y, Qian H, Dong L, Redmond TM. Mouse model of human RPE65 P25L hypomorph resembles wild type under normal light rearing but is fully resistant to acute light damage. Hum Mol Genet 2015; 24:4417-28. [PMID: 25972377 DOI: 10.1093/hmg/ddv178] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 05/11/2015] [Indexed: 01/21/2023] Open
Abstract
Human RPE65 mutations cause a spectrum of blinding retinal dystrophies from severe early-onset disease to milder manifestations. The RPE65 P25L missense mutation, though having <10% of wild-type (WT) activity, causes relatively mild retinal degeneration. To better understand these mild forms of RPE65-related retinal degeneration, and their effect on cone photoreceptor survival, we generated an Rpe65/P25L knock-in (KI/KI) mouse model. We found that, when subject to the low-light regime (∼100 lux) of regular mouse housing, homozygous Rpe65/P25L KI/KI mice are morphologically and functionally very similar to WT siblings. While mutant protein expression is decreased by over 80%, KI/KI mice retinae retain comparable 11-cis-retinal levels with WT. Consistently, the scotopic and photopic electroretinographic (ERG) responses to single-flash stimuli also show no difference between KI/KI and WT mice. However, the recovery of a-wave response following moderate visual pigment bleach is delayed in KI/KI mice. Importantly, KI/KI mice show significantly increased resistance to high-intensity (20 000 lux for 30 min) light-induced retinal damage (LIRD) as compared with WT, indicating impaired rhodopsin regeneration in KI/KI. Taken together, the Rpe65/P25L mutant produces sufficient chromophore under normal conditions to keep opsins replete and thus manifests a minimal phenotype. Only when exposed to intensive light is this hypomorphic mutation manifested physiologically, as its reduced expression and catalytic activity protects against the successive cycles of opsin regeneration underlying LIRD. These data also help define minimal requirements of chromophore for photoreceptor survival in vivo and may be useful in assessing a beneficial therapeutic dose for RPE65 gene therapy in humans.
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Affiliation(s)
- Yan Li
- Laboratory of Retinal Cell and Molecular Biology
| | - Shirley Yu
- Laboratory of Retinal Cell and Molecular Biology
| | - Todd Duncan
- Laboratory of Retinal Cell and Molecular Biology
| | | | - Pinghu Liu
- Genetic Engineering Core, National Eye Institute/NIH, Bethesda, MD, USA
| | - Erelda Gene
- Laboratory of Retinal Cell and Molecular Biology
| | | | | | - Lijin Dong
- Genetic Engineering Core, National Eye Institute/NIH, Bethesda, MD, USA
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244
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Abstract
Clinical trials treating inherited retinal dystrophy caused by RPE65 mutations had put retinal gene therapy at the forefront of gene therapy. Both successes and limitations in these clinical trials have fueled developments in gene vectors, which continue to further advance the field. These novel gene vectors aim to more safely and efficiently transduce retinal cells, expand the gene packaging capacity of AAV, and utilize new strategies to correct the varying mechanisms of dysfunction found with inherited retinal dystrophies. With recent clinical trials and numerous pre-clinical studies utilizing these novel vectors, the future of ocular gene therapy continues to hold vast potential.
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Affiliation(s)
- Cristy A Ku
- Center for Neuroscience, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia, 26505, USA
| | - Mark E Pennesi
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, 97239, USA
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245
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Li S, Hu J, Jin RJ, Aiyar A, Jacobson SG, Bok D, Jin M. Temperature-sensitive retinoid isomerase activity of RPE65 mutants associated with Leber Congenital Amaurosis. J Biochem 2015; 158:115-25. [PMID: 25752820 DOI: 10.1093/jb/mvv028] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Accepted: 01/26/2015] [Indexed: 12/22/2022] Open
Abstract
RPE65 is a membrane-associated retinoid isomerase involved in the visual cycle responsible for sustaining vision. Many mutations in the human RPE65 gene are associated with distinct forms of retinal degenerative diseases. The pathogenic mechanisms for most of these mutations remain poorly understood. Here, we show that three Leber congenital amaurosis -associated RPE65 mutants (R91W, Y249C and R515W) undergo rapid proteasomal degradation mediated by the 26 S proteasome non-ATPase regulatory subunit 13 (PSMD13) in cultured human retinal pigment epithelium (RPE) cells. These mutant proteins formed cytosolic inclusion bodies or high molecular weight complexes via disulfide bonds. The mutations are mapped on non-active sites but severely reduced isomerase activity of RPE65. At 30°C, however, the enzymatic function and membrane-association of the mutant RPE65s are significantly rescued possibly due to proper folding. In addition, PSMD13 displayed a drastically decreased effect on degradation of the mutant proteins in the cells grown at 30°C. These results suggest that PSMD13 plays a critical role in regulating pathogenicity of the mutations and the molecular basis for the PSMD13-mediated rapid degradation and loss of function of the mutants is misfolding of RPE65.
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Affiliation(s)
- Songhua Li
- Department of Ophthalmology and Neuroscience Center, Louisiana State University Health Sciences Center, New Orleans, LA 70112 USA
| | - Jane Hu
- Jules Stein Eye Institute and Department of Neurobiology, University of California, Los Angeles, CA 90095 USA
| | - Robin J Jin
- State University of New York at Buffalo, Buffalo, NY 14214 USA
| | - Ashok Aiyar
- Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA 70112 USA; and
| | - Samuel G Jacobson
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA 19104 USA
| | - Dean Bok
- Jules Stein Eye Institute and Department of Neurobiology, University of California, Los Angeles, CA 90095 USA
| | - Minghao Jin
- Department of Ophthalmology and Neuroscience Center, Louisiana State University Health Sciences Center, New Orleans, LA 70112 USA;
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246
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Holt R, Brown L, Broadgate S, Butler R, Jagannath A, Downes S, Peirson S, Halford S. Identification of rod- and cone-specific expression signatures to identify candidate genes for retinal disease. Exp Eye Res 2015; 132:161-73. [DOI: 10.1016/j.exer.2015.01.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 12/22/2014] [Accepted: 01/06/2015] [Indexed: 01/05/2023]
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247
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Dai X, Zhang H, He Y, Qi Y, Chang B, Pang JJ. The frequency-response electroretinogram distinguishes cone and abnormal rod function in rd12 mice. PLoS One 2015; 10:e0117570. [PMID: 25706871 PMCID: PMC4338143 DOI: 10.1371/journal.pone.0117570] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 12/28/2014] [Indexed: 11/19/2022] Open
Abstract
Early studies on Rpe65 knockout mice reported that remaining visual function was attributable to cone function. However, this finding has been challenged more and more as time has passed. Electroretinograms (ERGs) showed that rd12 mice, a spontaneous animal model of RPE65 Leber’s congenital amaurosis, had sizeable photopic responses. Unfortunately, the recorded ERG waveform was difficult to interpret because of a remarkably delayed peak-time, which resembles a rod response more than a cone response. Here, we compare flicker ERGs in animals with normal rod and cone function (C57BL/6J mice), pure rod function (cpfl5 mice), and pure cone function (Rho-/- mice) under different adaptation levels and stimulus intensities. These responses were then compared with those obtained from rd12 mice. Our results showed that normal rods respond to low frequency flicker (5 and 15 Hz) and that normal cones respond to both low and high frequency flicker (5–35 Hz). As was seen in cpfl5 mice, rd12 mice had recordable responses to low frequency flicker (5 and 15Hz), but not to high frequency flicker (25 and 35 Hz). We hypothesize that abnormal rods may be the source of residual vision in rd12 mice, which is proved correct here with double mutant rd12mice. In this study, we show, for the first time, that frequency-response ERGs can effectively distinguish cone- and rod-driven responses in the rd12 mouse. It is another simple and valid method for evaluating the respective contributions of retinal rods and cones.
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Affiliation(s)
- Xufeng Dai
- Eye Hospital, School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
- Department of Ophthalmology, College of Medicine, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
| | - Hua Zhang
- Eye Hospital, School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
| | - Ying He
- Eye Hospital, School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
| | - Yan Qi
- Eye Hospital, School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
| | - Bo Chang
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Ji-jing Pang
- Eye Hospital, School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
- Department of Ophthalmology, College of Medicine, University of Florida, Gainesville, Florida, United States of America
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248
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Murray AR, Vuong L, Brobst D, Fliesler SJ, Peachey NS, Gorbatyuk MS, Naash MI, Al-Ubaidi MR. Glycosylation of rhodopsin is necessary for its stability and incorporation into photoreceptor outer segment discs. Hum Mol Genet 2015; 24:2709-23. [PMID: 25637522 DOI: 10.1093/hmg/ddv031] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 01/26/2015] [Indexed: 11/14/2022] Open
Abstract
Rhodopsin, a G-protein coupled receptor, most abundant protein in retinal rod photoreceptors, is glycosylated at asparagines-2 and 15 on its N-terminus. To understand the role of rhodopsin's glycosylation in vivo, we generated and characterized a transgenic mouse model that expresses a non-glycosylated form of rhodopsin. We show that lack of glycosylation triggers a dominant form of progressive retinal degeneration. Electron microscopic examination of retinas at postnatal day 17 revealed the presence of vacuolar structures that distorted rod photoreceptor outer segments and became more prominent with age. Expression of non-glycosylated rhodopsin alone showed that it is unstable and is regulated via ubiquitin-mediated proteasomal degradation at the base of outer segments. We observed similar vacuolization in outer segments of transgenic mice expressing human rhodopsin with a T17M mutation (hT17M), suggesting that the mechanism responsible for the degenerative process in mice expressing the non-glycosylated rhodopsin and the RHO(hT17M) mice is likely the cause of phenotype observed in retinitis pigmentosa patients carrying T17M mutation.
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Affiliation(s)
- Anne R Murray
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Linda Vuong
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Daniel Brobst
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Steven J Fliesler
- Research Service, VA Western New York Healthcare System, and Departments of Ophthalmology and Biochemistry, University of Buffalo/State University of New York, Buffalo, NY 14215, USA
| | - Neal S Peachey
- Ophthalmic Research, Cleveland Clinic, Research Service, Cleveland VA Medical Center, Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH 44195, USA and
| | - Marina S Gorbatyuk
- Department of Vision Sciences, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Muna I Naash
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Muayyad R Al-Ubaidi
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA,
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249
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Pierce EA, Bennett J. The Status of RPE65 Gene Therapy Trials: Safety and Efficacy. Cold Spring Harb Perspect Med 2015; 5:a017285. [PMID: 25635059 DOI: 10.1101/cshperspect.a017285] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Several groups have reported the results of clinical trials of gene augmentation therapy for Leber congenital amaurosis (LCA) because of mutations in the RPE65 gene. These studies have used subretinal injection of adeno-associated virus (AAV) vectors to deliver the human RPE65 cDNA to the retinal pigment epithelial (RPE) cells of the treated eyes. In all of the studies reported to date, this approach has been shown to be both safe and effective. The successful clinical trials of gene augmentation therapy for retinal degeneration caused by mutations in the RPE65 gene sets the stage for broad application of gene therapy to treat retinal degenerative disorders.
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Affiliation(s)
- Eric A Pierce
- Department of Ophthalmology, Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary and Harvard Medical School, Boston, Massachusetts 02114
| | - Jean Bennett
- Department of Ophthalmology, Center for Advanced Retinal and Ophthalmic Therapeutics, F.M. Kirby Center for Molecular Ophthalmology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104
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250
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Ciliary ectosomes: transmissions from the cell's antenna. Trends Cell Biol 2015; 25:276-85. [PMID: 25618328 DOI: 10.1016/j.tcb.2014.12.008] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 12/20/2014] [Accepted: 12/22/2014] [Indexed: 12/21/2022]
Abstract
The cilium is the site of function for a variety of membrane receptors, enzymes and signal transduction modules crucial for a spectrum of cellular processes. Through targeted transport and selective gating mechanisms, the cell localizes specific proteins to the cilium that equip it for the role of sensory antenna. This capacity of the cilium to serve as a specialized compartment where specific proteins can be readily concentrated for sensory reception also makes it an ideal organelle to employ for the regulated emission of specific biological material and information. In this review we present and discuss an emerging body of evidence centered on ciliary ectosomes - bioactive vesicles released from the surface of the cilium.
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