1
|
Kerschensteiner D. Losing, preserving, and restoring vision from neurodegeneration in the eye. Curr Biol 2023; 33:R1019-R1036. [PMID: 37816323 PMCID: PMC10575673 DOI: 10.1016/j.cub.2023.08.044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/12/2023]
Abstract
The retina is a part of the brain that sits at the back of the eye, looking out onto the world. The first neurons of the retina are the rod and cone photoreceptors, which convert changes in photon flux into electrical signals that are the basis of vision. Rods and cones are frequent targets of heritable neurodegenerative diseases that cause visual impairment, including blindness, in millions of people worldwide. This review summarizes the diverse genetic causes of inherited retinal degenerations (IRDs) and their convergence onto common pathogenic mechanisms of vision loss. Currently, there are few effective treatments for IRDs, but recent advances in disparate areas of biology and technology (e.g., genome editing, viral engineering, 3D organoids, optogenetics, semiconductor arrays) discussed here enable promising efforts to preserve and restore vision in IRD patients with implications for neurodegeneration in less approachable brain areas.
Collapse
Affiliation(s)
- Daniel Kerschensteiner
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Biomedical Engineering, Washington University School of Medicine, St. Louis, MO 63110, USA.
| |
Collapse
|
2
|
Mizobuchi K, Hayashi T, Ueno S, Kondo M, Terasaki H, Aoki T, Nakano T. One-Year Outcomes of Oral Treatment With Alga Capsules Containing Low Levels of 9-cis-β-Carotene in RDH5-Related Fundus Albipunctatus. Am J Ophthalmol 2023; 254:193-202. [PMID: 37343743 DOI: 10.1016/j.ajo.2023.06.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 06/13/2023] [Accepted: 06/13/2023] [Indexed: 06/23/2023]
Abstract
PURPOSE This study aimed to clarify the effect of 1-year oral treatment with 9-cis-β-carotene-rich alga Dunaliella bardawil (Dunaliella supplementation) using full-field electroretinography (ERG) in patients with RDH5-related fundus albipunctatus (FAP). DESIGN Prospective, interventional case series. PARTICIPANTS The study included 12 patients (23 eyes) with RDH5-related FAP. METHODS Twelve patients (23 eyes) with RDH5-related FAP received Dunaliella supplementation (total daily dose of β-carotene was 74.0 mg, comprising 28.4 mg 9-cis-β-carotene and 45.6 mg all-trans-β-carotene at a ratio of 1:1.6) for 1 year and underwent ophthalmic examinations, including full-field ERG at baseline, 3 months, and 1 year after the initial treatment. MAIN OUTCOME MEASURES The main outcome was changes in the amplitudes of responses of full-field ERG before and after treatment. A linear mixed-effects model was used to evaluate the adjusted mean difference between the amplitude of each response pretreatment and posttreatment. RESULTS Prolonged dark adaptation (DA) responses at 3 months revealed a significant impairment in the b-wave of DA 0.01 (adjusted mean difference, -34.7, 95% CI, -66.8 to -2.73, P = .041) and a-wave of DA 3.0 (-29.0, 95% CI, -50.6 to -7.41, P = .013) and DA 10.0 (-40.4, 95% CI, -67.8 to -13.0, P = .007), which were also observed at 1 year. Additionally, prolonged DA and light adaptation (LA) responses revealed statistically significant impairment at 1 year in the b-wave of DA 3.0 (-43.8, 95% CI, -82.9 to -4.78, P = .035), DA 10.0 (-59.7, 95% CI, -101.8 to -17.61, P = .009), LA 3.0 (-7.31, 95% CI, -13.6 to -1.04, P = .029), and LA 3.0 flicker (-7.53, 95% CI, -12.7 to -2.34, P = .007). CONCLUSIONS Our study results suggest that Dunaliella supplementation comprising low levels of 9-cis-β-carotene compared with those reported in a previous study (1:1 ratio) adversely affects ERG amplitudes in patients with RDH5-related FAP.
Collapse
Affiliation(s)
- Kei Mizobuchi
- From the Department of Ophthalmology, The Jikei University School of Medicine, Tokyo, Japan (K.M., T.H., T.N.)
| | - Takaaki Hayashi
- From the Department of Ophthalmology, The Jikei University School of Medicine, Tokyo, Japan (K.M., T.H., T.N.); Department of Ophthalmology, Katsushika Medical Center, The Jikei University School of Medicine, Tokyo, Japan (T.H.).
| | - Shinji Ueno
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Aichi, Japan (S.U., H.T.); Department of Ophthalmology, Hirosaki University Graduate School of Medicine, Aomori, Japan (S.U.)
| | - Mineo Kondo
- Department of Ophthalmology, Mie University Graduate School of Medicine, Mie, Japan (M.K.)
| | - Hiroko Terasaki
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Aichi, Japan (S.U., H.T.)
| | - Takuya Aoki
- Division of Clinical Epidemiology, Research Center for Medical Sciences, The Jikei University School of Medicine, Tokyo, Japan (T.A.)
| | - Tadashi Nakano
- From the Department of Ophthalmology, The Jikei University School of Medicine, Tokyo, Japan (K.M., T.H., T.N.)
| |
Collapse
|
3
|
Vöcking O, Macias-Muñoz A, Jaeger SJ, Oakley TH. Deep Diversity: Extensive Variation in the Components of Complex Visual Systems across Animals. Cells 2022; 11:cells11243966. [PMID: 36552730 PMCID: PMC9776813 DOI: 10.3390/cells11243966] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 11/19/2022] [Accepted: 12/02/2022] [Indexed: 12/13/2022] Open
Abstract
Understanding the molecular underpinnings of the evolution of complex (multi-part) systems is a fundamental topic in biology. One unanswered question is to what the extent do similar or different genes and regulatory interactions underlie similar complex systems across species? Animal eyes and phototransduction (light detection) are outstanding systems to investigate this question because some of the genetics underlying these traits are well characterized in model organisms. However, comparative studies using non-model organisms are also necessary to understand the diversity and evolution of these traits. Here, we compare the characteristics of photoreceptor cells, opsins, and phototransduction cascades in diverse taxa, with a particular focus on cnidarians. In contrast to the common theme of deep homology, whereby similar traits develop mainly using homologous genes, comparisons of visual systems, especially in non-model organisms, are beginning to highlight a "deep diversity" of underlying components, illustrating how variation can underlie similar complex systems across taxa. Although using candidate genes from model organisms across diversity was a good starting point to understand the evolution of complex systems, unbiased genome-wide comparisons and subsequent functional validation will be necessary to uncover unique genes that comprise the complex systems of non-model groups to better understand biodiversity and its evolution.
Collapse
Affiliation(s)
- Oliver Vöcking
- Department of Biology, University of Kentucky, Lexington, KY 40508, USA
| | - Aide Macias-Muñoz
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA 93106, USA
| | - Stuart J. Jaeger
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA 93106, USA
| | - Todd H. Oakley
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA 93106, USA
- Correspondence:
| |
Collapse
|
4
|
Das A, Imanishi Y. Drug Discovery Strategies for Inherited Retinal Degenerations. BIOLOGY 2022; 11:1338. [PMID: 36138817 PMCID: PMC9495580 DOI: 10.3390/biology11091338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 08/31/2022] [Accepted: 09/07/2022] [Indexed: 12/03/2022]
Abstract
Inherited retinal degeneration is a group of blinding disorders afflicting more than 1 in 4000 worldwide. These disorders frequently cause the death of photoreceptor cells or retinal ganglion cells. In a subset of these disorders, photoreceptor cell death is a secondary consequence of retinal pigment epithelial cell dysfunction or degeneration. This manuscript reviews current efforts in identifying targets and developing small molecule-based therapies for these devastating neuronal degenerations, for which no cures exist. Photoreceptors and retinal ganglion cells are metabolically demanding owing to their unique structures and functional properties. Modulations of metabolic pathways, which are disrupted in most inherited retinal degenerations, serve as promising therapeutic strategies. In monogenic disorders, great insights were previously obtained regarding targets associated with the defective pathways, including phototransduction, visual cycle, and mitophagy. In addition to these target-based drug discoveries, we will discuss how phenotypic screening can be harnessed to discover beneficial molecules without prior knowledge of their mechanisms of action. Because of major anatomical and biological differences, it has frequently been challenging to model human inherited retinal degeneration conditions using small animals such as rodents. Recent advances in stem cell-based techniques are opening new avenues to obtain pure populations of human retinal ganglion cells and retinal organoids with photoreceptor cells. We will discuss concurrent ideas of utilizing stem-cell-based disease models for drug discovery and preclinical development.
Collapse
Affiliation(s)
- Arupratan Das
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Yoshikazu Imanishi
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| |
Collapse
|
5
|
Fernandez-Gonzalez P, Mas-Sanchez A, Garriga P. Polyphenols and Visual Health: Potential Effects on Degenerative Retinal Diseases. Molecules 2021; 26:3407. [PMID: 34199888 PMCID: PMC8200069 DOI: 10.3390/molecules26113407] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 06/01/2021] [Accepted: 06/02/2021] [Indexed: 12/26/2022] Open
Abstract
Dietary polyphenols are a group of natural compounds that have been proposed to have beneficial effects on human health. They were first known for their antioxidant properties, but several studies over the years have shown that these compounds can exert protective effects against chronic diseases. Nonetheless, the mechanisms underlying these potential benefits are still uncertain and contradictory effects have been reported. In this review, we analyze the potential effects of polyphenol compounds on some visual diseases, with a special focus on retinal degenerative diseases. Current effective therapies for the treatment of such retinal diseases are lacking and new strategies need to be developed. For this reason, there is currently a renewed interest in finding novel ligands (or known ligands with previously unexpected features) that could bind to retinal photoreceptors and modulate their molecular properties. Some polyphenols, especially flavonoids (e.g., quercetin and tannic acid), could attenuate light-induced receptor damage and promote visual health benefits. Recent evidence suggests that certain flavonoids could help stabilize the correctly folded conformation of the visual photoreceptor protein rhodopsin and offset the deleterious effect of retinitis pigmentosa mutations. In this regard, certain polyphenols, like the flavonoids mentioned before, have been shown to improve the stability, expression, regeneration and folding of rhodopsin mutants in experimental in vitro studies. Moreover, these compounds appear to improve the integration of the receptor into the cell membrane while acting against oxidative stress at the same time. We anticipate that polyphenol compounds can be used to target visual photoreceptor proteins, such as rhodopsin, in a way that has only been recently proposed and that these can be used in novel approaches for the treatment of retinal degenerative diseases like retinitis pigmentosa; however, studies in this field are limited and further research is needed in order to properly characterize the effects of these compounds on retinal degenerative diseases through the proposed mechanisms.
Collapse
Affiliation(s)
| | | | - Pere Garriga
- Grup de Biotecnologia Molecular i Industrial, Centre de Biotecnologia Molecular, Departament d’Enginyeria Química, Universitat Politècnica de Catalunya, Edifici Gaia, 08222 Terrassa, Spain; (P.F.-G.); (A.M.-S.)
| |
Collapse
|
6
|
Laradji AM, Kolesnikov AV, Karakoçak BB, Kefalov VJ, Ravi N. Redox-Responsive Hyaluronic Acid-Based Nanogels for the Topical Delivery of the Visual Chromophore to Retinal Photoreceptors. ACS OMEGA 2021; 6:6172-6184. [PMID: 33718708 PMCID: PMC7948240 DOI: 10.1021/acsomega.0c05535] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 02/04/2021] [Indexed: 05/08/2023]
Abstract
Delivering therapeutics to the posterior segment of the eye is challenging due to various anatomical and physical barriers. While significant improvements have been realized by introducing direct injections to diseased sites, these approaches come with potential side effects that can range from simple inflammation to severe retinal damage. The topical instillation of drugs remains a safer and preferred alternative for patients' compliance. Here, we report the synthesis of penetratin-complexed, redox-responsive hyaluronic acid-based nanogels for the triggered release and delivery of therapeutics to the posterior part of the eye via topical application. The synthesized nanogels were shown to release their load only when exposed to a reducing environment, similar to the cytoplasm. As a model drug, visual chromophore analog, 9-cis-retinal, was loaded into nanogels and efficiently delivered to the mouse retina's photoreceptors when applied topically. Electroretinogram measurements showed a partial recovery of photoreceptor function in all treated eyes versus untreated controls. To the best of our knowledge, this report constitutes the first attempt to use a topically applied triggered-release drug delivery system to target the pigmented layer of the retina, in addition to the first attempt to deliver the visual chromophore topically.
Collapse
Affiliation(s)
- Amine M. Laradji
- Department
of Ophthalmology and Visual Sciences, Washington
University School of Medicine, St. Louis, Missouri 63110, United States
- Department
of Veterans Affairs, St. Louis Medical Center, St. Louis, Missouri 63106, United States
| | - Alexander V. Kolesnikov
- Department
of Ophthalmology and Visual Sciences, Washington
University School of Medicine, St. Louis, Missouri 63110, United States
| | - Bedia B. Karakoçak
- Department
of Ophthalmology and Visual Sciences, Washington
University School of Medicine, St. Louis, Missouri 63110, United States
- Department
of Veterans Affairs, St. Louis Medical Center, St. Louis, Missouri 63106, United States
| | - Vladimir J. Kefalov
- Department
of Ophthalmology and Visual Sciences, Washington
University School of Medicine, St. Louis, Missouri 63110, United States
| | - Nathan Ravi
- Department
of Ophthalmology and Visual Sciences, Washington
University School of Medicine, St. Louis, Missouri 63110, United States
- Department
of Veterans Affairs, St. Louis Medical Center, St. Louis, Missouri 63106, United States
- Department
of Energy, Environmental, and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63110, United States
| |
Collapse
|
7
|
Choi EH, Daruwalla A, Suh S, Leinonen H, Palczewski K. Retinoids in the visual cycle: role of the retinal G protein-coupled receptor. J Lipid Res 2021; 62:100040. [PMID: 32493732 PMCID: PMC7910522 DOI: 10.1194/jlr.tr120000850] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 05/20/2020] [Indexed: 12/13/2022] Open
Abstract
Driven by the energy of a photon, the visual pigments in rod and cone photoreceptor cells isomerize 11-cis-retinal to the all-trans configuration. This photochemical reaction initiates the signal transduction pathway that eventually leads to the transmission of a visual signal to the brain and leaves the opsins insensitive to further light stimulation. For the eye to restore light sensitivity, opsins require recharging with 11-cis-retinal. This trans-cis back conversion is achieved through a series of enzymatic reactions composing the retinoid (visual) cycle. Although it is evident that the classical retinoid cycle is critical for vision, the existence of an adjunct pathway for 11-cis-retinal regeneration has been debated for many years. Retinal pigment epithelium (RPE)-retinal G protein-coupled receptor (RGR) has been identified previously as a mammalian retinaldehyde photoisomerase homologous to retinochrome found in invertebrates. Using pharmacological, genetic, and biochemical approaches, researchers have now established the physiological relevance of the RGR in 11-cis-retinal regeneration. The photoisomerase activity of RGR in the RPE and Müller glia explains how the eye can remain responsive in daylight. In this review, we will focus on retinoid metabolism in the eye and visual chromophore regeneration mediated by RGR.
Collapse
Affiliation(s)
- Elliot H Choi
- Department of Ophthalmology, Gavin Herbert Eye Institute, Center for Translational Vision Research, University of California, Irvine, CA, USA; Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA.
| | - Anahita Daruwalla
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA; Departments of Physiology and Biophysics, and Chemistry, University of California, Irvine, CA, USA
| | - Susie Suh
- Department of Ophthalmology, Gavin Herbert Eye Institute, Center for Translational Vision Research, University of California, Irvine, CA, USA; Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA
| | - Henri Leinonen
- Department of Ophthalmology, Gavin Herbert Eye Institute, Center for Translational Vision Research, University of California, Irvine, CA, USA
| | - Krzysztof Palczewski
- Department of Ophthalmology, Gavin Herbert Eye Institute, Center for Translational Vision Research, University of California, Irvine, CA, USA; Departments of Physiology and Biophysics, and Chemistry, University of California, Irvine, CA, USA.
| |
Collapse
|
8
|
Kiser PD, Palczewski K. Pathways and disease-causing alterations in visual chromophore production for vertebrate vision. J Biol Chem 2021; 296:100072. [PMID: 33187985 PMCID: PMC7948990 DOI: 10.1074/jbc.rev120.014405] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 11/12/2020] [Accepted: 11/13/2020] [Indexed: 12/14/2022] Open
Abstract
All that we view of the world begins with an ultrafast cis to trans photoisomerization of the retinylidene chromophore associated with the visual pigments of rod and cone photoreceptors. The continual responsiveness of these photoreceptors is then sustained by regeneration processes that convert the trans-retinoid back to an 11-cis configuration. Recent biochemical and electrophysiological analyses of the retinal G-protein-coupled receptor (RGR) suggest that it could sustain the responsiveness of photoreceptor cells, particularly cones, even under bright light conditions. Thus, two mechanisms have evolved to accomplish the reisomerization: one involving the well-studied retinoid isomerase (RPE65) and a second photoisomerase reaction mediated by the RGR. Impairments to the pathways that transform all-trans-retinal back to 11-cis-retinal are associated with mild to severe forms of retinal dystrophy. Moreover, with age there also is a decline in the rate of chromophore regeneration. Both pharmacological and genetic approaches are being used to bypass visual cycle defects and consequently mitigate blinding diseases. Rapid progress in the use of genome editing also is paving the way for the treatment of disparate retinal diseases. In this review, we provide an update on visual cycle biochemistry and then discuss visual-cycle-related diseases and emerging therapeutics for these disorders. There is hope that these advances will be helpful in treating more complex diseases of the eye, including age-related macular degeneration (AMD).
Collapse
Affiliation(s)
- Philip D Kiser
- The Department of Physiology & Biophysics, University of California, Irvine, California, USA; Research Service, The VA Long Beach Health Care System, Long Beach, California, USA; The Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, California, USA.
| | - Krzysztof Palczewski
- The Department of Physiology & Biophysics, University of California, Irvine, California, USA; The Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, California, USA; The Department of Chemistry, University of California, Irvine, California, USA.
| |
Collapse
|
9
|
Properties and Therapeutic Implications of an Enigmatic D477G RPE65 Variant Associated with Autosomal Dominant Retinitis Pigmentosa. Genes (Basel) 2020; 11:genes11121420. [PMID: 33261050 PMCID: PMC7760593 DOI: 10.3390/genes11121420] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 11/24/2020] [Accepted: 11/24/2020] [Indexed: 12/22/2022] Open
Abstract
RPE65 isomerase, expressed in the retinal pigmented epithelium (RPE), is an enzymatic component of the retinoid cycle, converting all-trans retinyl ester into 11-cis retinol, and it is essential for vision, because it replenishes the photon capturing 11-cis retinal. To date, almost 200 loss-of-function mutations have been identified within the RPE65 gene causing inherited retinal dystrophies, most notably Leber congenital amaurosis (LCA) and autosomal recessive retinitis pigmentosa (arRP), which are both severe and early onset disease entities. We previously reported a mutation, D477G, co-segregating with the disease in a late-onset form of autosomal dominant RP (adRP) with choroidal involvement; uniquely, it is the only RPE65 variant to be described with a dominant component. Families or individuals with this variant have been encountered in five countries, and a number of subsequent studies have been reported in which the molecular biological and physiological properties of the variant have been studied in further detail, including observations of possible novel functions in addition to reduced RPE65 enzymatic activity. With regard to the latter, a human phase 1b proof-of-concept study has recently been reported in which aspects of remaining vision were improved for up to one year in four of five patients with advanced disease receiving a single one-week oral dose of 9-cis retinaldehyde, which is the first report showing efficacy and safety of an oral therapy for a dominant form of RP. Here, we review data accrued from published studies investigating molecular mechanisms of this unique variant and include hitherto unpublished material on the clinical spectrum of disease encountered in patients with the D477G variant, which, in many cases bears striking similarities to choroideremia.
Collapse
|
10
|
Abstract
The visual phototransduction cascade begins with a cis-trans photoisomerization of a retinylidene chromophore associated with the visual pigments of rod and cone photoreceptors. Visual opsins release their all-trans-retinal chromophore following photoactivation, which necessitates the existence of pathways that produce 11-cis-retinal for continued formation of visual pigments and sustained vision. Proteins in the retinal pigment epithelium (RPE), a cell layer adjacent to the photoreceptor outer segments, form the well-established "dark" regeneration pathway known as the classical visual cycle. This pathway is sufficient to maintain continuous rod function and support cone photoreceptors as well although its throughput has to be augmented by additional mechanism(s) to maintain pigment levels in the face of high rates of photon capture. Recent studies indicate that the classical visual cycle works together with light-dependent processes in both the RPE and neural retina to ensure adequate 11-cis-retinal production under natural illuminances that can span ten orders of magnitude. Further elucidation of the interplay between these complementary systems is fundamental to understanding how cone-mediated vision is sustained in vivo. Here, we describe recent advances in understanding how 11-cis-retinal is synthesized via light-dependent mechanisms.
Collapse
|
11
|
Wang X, Shan X, Gregory-Evans K, Gregory-Evans CY. RNA-based therapies in animal models of Leber congenital amaurosis causing blindness. PRECISION CLINICAL MEDICINE 2020; 3:113-126. [PMID: 35692607 PMCID: PMC8985810 DOI: 10.1093/pcmedi/pbaa009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 03/05/2020] [Accepted: 03/10/2020] [Indexed: 11/14/2022] Open
Abstract
Abstract
Leber congenital amaurosis (LCA) is a severe, genetically heterogeneous recessive eye disease in which ~ 35% of gene mutations are in-frame nonsense mutations coding for loss-of-function premature termination codons (PTCs) in mRNA. Nonsense suppression therapy allows read-through of PTCs leading to production of full-length protein. A limitation of nonsense suppression is that nonsense-mediated decay (NMD) degrades PTC-containing RNA transcripts. The purpose of this study was to determine whether inhibition of NMD could improve nonsense suppression efficacy in vivo. Using a high-throughput approach in the recessive cep290 zebrafish model of LCA (cep290;Q1223X), we first tested the NMD inhibitor Amlexanox in combination with the nonsense suppression drug Ataluren. We observed reduced retinal cell death and improved visual function. With these positive data, we next investigated whether this strategy was also applicable across species in two mammalian models: Rd12 (rpe65;R44X) and Rd3 (rd3;R107X) mouse models of LCA. In the Rd12 model, cell death was reduced, RPE65 protein was produced, and in vivo visual function testing was improved. We establish for the first time that the mechanism of action of Amlexanox in Rd12 retina was through reduced UPF1 phosphorylation. In the Rd3 model, however, no beneficial effect was observed with Ataluren alone or in combination with Amlexanox. This variation in response establishes that some forms of nonsense mutation LCA can be targeted by RNA therapies, but that this needs to be verified for each genotype. The implementation of precision medicine by identifying better responders to specific drugs is essential for development of validated retinal therapies.
Collapse
Affiliation(s)
- Xia Wang
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver BC V5Z 3N9, Canada
| | - Xianghong Shan
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver BC V5Z 3N9, Canada
| | - Kevin Gregory-Evans
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver BC V5Z 3N9, Canada
| | - Cheryl Y Gregory-Evans
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver BC V5Z 3N9, Canada
| |
Collapse
|
12
|
von Lintig J, Moon J, Babino D. Molecular components affecting ocular carotenoid and retinoid homeostasis. Prog Retin Eye Res 2020; 80:100864. [PMID: 32339666 DOI: 10.1016/j.preteyeres.2020.100864] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 04/13/2020] [Accepted: 04/17/2020] [Indexed: 12/15/2022]
Abstract
The photochemistry of vision employs opsins and geometric isomerization of their covalently bound retinylidine chromophores. In different animal classes, these light receptors associate with distinct G proteins that either hyperpolarize or depolarize photoreceptor membranes. Vertebrates also use the acidic form of chromophore, retinoic acid, as the ligand of nuclear hormone receptors that orchestrate eye development. To establish and sustain these processes, animals must acquire carotenoids from the diet, transport them, and metabolize them to chromophore and retinoic acid. The understanding of carotenoid metabolism, however, lagged behind our knowledge about the biology of their receptor molecules. In the past decades, much progress has been made in identifying the genes encoding proteins that mediate the transport and enzymatic transformations of carotenoids and their retinoid metabolites. Comparative analysis in different animal classes revealed how evolutionary tinkering with a limited number of genes evolved different biochemical strategies to supply photoreceptors with chromophore. Mutations in these genes impair carotenoid metabolism and induce various ocular pathologies. This review summarizes this advancement and introduces the involved proteins, including the homeostatic regulation of their activities.
Collapse
Affiliation(s)
- Johannes von Lintig
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
| | - Jean Moon
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Darwin Babino
- Department of Ophthalmology, School of Medicine, University of Washington, Seattle, WA, USA
| |
Collapse
|
13
|
Ward R, Kaylor JJ, Cobice DF, Pepe DA, McGarrigle EM, Brockerhoff SE, Hurley JB, Travis GH, Kennedy BN. Non-photopic and photopic visual cycles differentially regulate immediate, early, and late phases of cone photoreceptor-mediated vision. J Biol Chem 2020; 295:6482-6497. [PMID: 32238432 DOI: 10.1074/jbc.ra119.011374] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 03/30/2020] [Indexed: 11/06/2022] Open
Abstract
Cone photoreceptors in the retina enable vision over a wide range of light intensities. However, the processes enabling cone vision in bright light (i.e. photopic vision) are not adequately understood. Chromophore regeneration of cone photopigments may require the retinal pigment epithelium (RPE) and/or retinal Müller glia. In the RPE, isomerization of all-trans-retinyl esters to 11-cis-retinol is mediated by the retinoid isomerohydrolase Rpe65. A putative alternative retinoid isomerase, dihydroceramide desaturase-1 (DES1), is expressed in RPE and Müller cells. The retinol-isomerase activities of Rpe65 and Des1 are inhibited by emixustat and fenretinide, respectively. Here, we tested the effects of these visual cycle inhibitors on immediate, early, and late phases of cone photopic vision. In zebrafish larvae raised under cyclic light conditions, fenretinide impaired late cone photopic vision, while the emixustat-treated zebrafish unexpectedly had normal vision. In contrast, emixustat-treated larvae raised under extensive dark-adaptation displayed significantly attenuated immediate photopic vision concomitant with significantly reduced 11-cis-retinaldehyde (11cRAL). Following 30 min of light, early photopic vision was recovered, despite 11cRAL levels remaining significantly reduced. Defects in immediate cone photopic vision were rescued in emixustat- or fenretinide-treated larvae following exogenous 9-cis-retinaldehyde supplementation. Genetic knockout of Des1 (degs1) or retinaldehyde-binding protein 1b (rlbp1b) did not eliminate photopic vision in zebrafish. Our findings define molecular and temporal requirements of the nonphotopic or photopic visual cycles for mediating vision in bright light.
Collapse
Affiliation(s)
- Rebecca Ward
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Dublin D04 V1W8, Ireland
| | - Joanna J Kaylor
- Jules Stein Eye Institute, UCLA School of Medicine, Los Angeles, California 90095
| | - Diego F Cobice
- Mass Spectrometry Centre, School of Biomedical Sciences, Biomedical Sciences Research Institute, Ulster University, Coleraine BT52 1SA, Northern Ireland
| | - Dionissia A Pepe
- Centre for Synthesis and Chemical Biology, UCD School of Chemistry, University College Dublin, Dublin D04 V1W8, Ireland
| | - Eoghan M McGarrigle
- Centre for Synthesis and Chemical Biology, UCD School of Chemistry, University College Dublin, Dublin D04 V1W8, Ireland
| | - Susan E Brockerhoff
- Department of Biochemistry, University of Washington, Seattle, Washington 98109.,Department of Ophthalmology, University of Washington, Seattle, Washington 98109
| | - James B Hurley
- Department of Biochemistry, University of Washington, Seattle, Washington 98109.,Department of Ophthalmology, University of Washington, Seattle, Washington 98109
| | - Gabriel H Travis
- Jules Stein Eye Institute, UCLA School of Medicine, Los Angeles, California 90095.,Department of Biological Chemistry, UCLA School of Medicine, Los Angeles, California 90095
| | - Breandán N Kennedy
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Dublin D04 V1W8, Ireland
| |
Collapse
|
14
|
Zhang J, Choi EH, Tworak A, Salom D, Leinonen H, Sander CL, Hoang TV, Handa JT, Blackshaw S, Palczewska G, Kiser PD, Palczewski K. Photic generation of 11- cis-retinal in bovine retinal pigment epithelium. J Biol Chem 2019; 294:19137-19154. [PMID: 31694912 DOI: 10.1074/jbc.ra119.011169] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 10/25/2019] [Indexed: 12/19/2022] Open
Abstract
Photoisomerization of the 11-cis-retinal chromophore of rod and cone visual pigments to an all-trans-configuration is the initiating event for vision in vertebrates. The regeneration of 11-cis-retinal, necessary for sustained visual function, is an endergonic process normally conducted by specialized enzyme systems. However, 11-cis-retinal also can be formed through reverse photoisomerization from all-trans-retinal. A nonvisual opsin known as retinal pigment epithelium (RPE)-retinal G-protein-coupled receptor (RGR) was previously shown to mediate visual chromophore regeneration in photic conditions, but conflicting results have cast doubt on its role as a photoisomerase. Here, we describe high-level production of 11-cis-retinal from RPE membranes stimulated by illumination at a narrow band of wavelengths. This activity was associated with RGR and enhanced by cellular retinaldehyde-binding protein (CRALBP), which binds the 11-cis-retinal produced by RGR and prevents its re-isomerization to all-trans-retinal. The activity was recapitulated with cells heterologously expressing RGR and with purified recombinant RGR. Using an RGR variant, K255A, we confirmed that a Schiff base linkage at Lys-255 is critical for substrate binding and isomerization. Single-cell RNA-Seq analysis of the retina and RPE tissue confirmed that RGR is expressed in human and bovine RPE and Müller glia, whereas mouse RGR is expressed in RPE but not in Müller glia. These results provide key insights into the mechanisms of physiological retinoid photoisomerization and suggest a novel mechanism by which RGR, in concert with CRALBP, regenerates the visual chromophore in the RPE under sustained light conditions.
Collapse
Affiliation(s)
- Jianye Zhang
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, California 92697
| | - Elliot H Choi
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, California 92697.,Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106
| | - Aleksander Tworak
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, California 92697
| | - David Salom
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, California 92697
| | - Henri Leinonen
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, California 92697
| | - Christopher L Sander
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, California 92697.,Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106
| | - Thanh V Hoang
- Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - James T Handa
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287
| | - Seth Blackshaw
- Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.,Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287
| | | | - Philip D Kiser
- Department of Physiology and Biophysics, University of California, Irvine, California 92697.,Research Service, Veterans Affairs Long Beach Healthcare System, Long Beach, California 90822
| | - Krzysztof Palczewski
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, California 92697
| |
Collapse
|
15
|
Long-term treatment with 9-cis-β-carotene rich alga Dunaliella bardawil ameliorates photoreceptor degeneration in a mouse model of retinoid cycle defect. ALGAL RES 2019. [DOI: 10.1016/j.algal.2019.101607] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
16
|
Wang SB, Xu T, Peng S, Singh D, Ghiassi-Nejad M, Adelman RA, Rizzolo LJ. Disease-associated mutations of claudin-19 disrupt retinal neurogenesis and visual function. Commun Biol 2019; 2:113. [PMID: 30937396 PMCID: PMC6433901 DOI: 10.1038/s42003-019-0355-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 02/15/2019] [Indexed: 12/13/2022] Open
Abstract
Mutations of claudin-19 cause Familial Hypomagnesaemia and Hypercalciuria, Nephrocalcinosis with Ocular Involvement. To study the ocular disease without the complications of the kidney disease, naturally occurring point mutations of human CLDN19 were recreated in human induced pluripotent cells or overexpressed in the retinae of newborn mice. In human induced pluripotent cells, we show that the mutation affects retinal neurogenesis and maturation of retinal pigment epithelium (RPE). In mice, the mutations diminish the P1 wave of the electroretinogram, activate apoptosis in the outer nuclear layer, and alter the morphology of bipolar cells. If mice are given 9-cis-retinal to counter the loss of retinal isomerase, the P1 wave is partially restored. The ARPE19 cell line fails to express claudin-19. Exogenous expression of wild type, but not mutant claudin-19, increases the expression of RPE signature genes. Mutated claudin-19 affects multiple stages of RPE and retinal differentiation through its effects on multiple functions of the RPE.
Collapse
Affiliation(s)
- Shao-Bin Wang
- Department of Surgery, Yale University, PO Box 208062, New Haven, CT USA
- Department of Ophthalmology, Yale University, 40 Temple Street, New Haven, CT USA
- Present Address: Center for Advanced Vision Science, Department of Ophthalmology, School of Medicine, University of Virginia, Charlottesville, VA 22908 USA
| | - Tao Xu
- Department of Surgery, Yale University, PO Box 208062, New Haven, CT USA
- Department of Ophthalmology, Yale University, 40 Temple Street, New Haven, CT USA
- Aier School of Ophthalmology, Central South University, 198 Furong Middle Ave Section 2, Tianxin District, Changsha, China
| | - Shaomin Peng
- Aier School of Ophthalmology, Central South University, 198 Furong Middle Ave Section 2, Tianxin District, Changsha, China
| | - Deepti Singh
- Department of Surgery, Yale University, PO Box 208062, New Haven, CT USA
- Department of Ophthalmology, Yale University, 40 Temple Street, New Haven, CT USA
- Present Address: Department of Ophthalmology, The Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, 20 Staniford St., Boston, MA 02114 USA
| | - Maryam Ghiassi-Nejad
- Department of Surgery, Yale University, PO Box 208062, New Haven, CT USA
- Department of Ophthalmology, Yale University, 40 Temple Street, New Haven, CT USA
| | - Ron A. Adelman
- Department of Ophthalmology, Yale University, 40 Temple Street, New Haven, CT USA
| | - Lawrence J. Rizzolo
- Department of Surgery, Yale University, PO Box 208062, New Haven, CT USA
- Department of Ophthalmology, Yale University, 40 Temple Street, New Haven, CT USA
| |
Collapse
|
17
|
Sher I, Tzameret A, Peri-Chen S, Edelshtain V, Ioffe M, Sayer A, Buzhansky L, Gazit E, Rotenstreich Y. Synthetic 9-cis-beta-carotene inhibits photoreceptor degeneration in cultures of eye cups from rpe65rd12 mouse model of retinoid cycle defect. Sci Rep 2018; 8:6130. [PMID: 29666392 PMCID: PMC5904152 DOI: 10.1038/s41598-018-24439-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 03/29/2018] [Indexed: 12/22/2022] Open
Abstract
The retinoid cycle enzymes regenerate the visual chromophore 11-cis retinal to enable vision. Mutations in the genes encoding the proteins of the retinoid cycle are the leading cause for recessively inherited retinal dystrophies such as retinitis pigmentosa, Leber congenital amaurosis, congenital cone-rod dystrophy and fundus albipunctatus. Currently there is no treatment for these blinding diseases. In previous studies we demonstrated that oral treatment with the 9-cis-β-carotene rich Dunaliella Bardawil algae powder significantly improved visual and retinal functions in patients with retinitis pigmentosa and fundus albipunctatus. Here we developed a convenient and economical synthetic route for biologically active 9-cis-β-carotene from inexpensive building materials and demonstrated that the molecule is stable for at least one month. Synthetic 9-cis-β-carotene rescued cone photoreceptors from degeneration in eye cup cultures of mice with a retinoid cycle genetic defect. This study suggests that synthetic 9-cis-β-carotene may serve as an effective treatment for retinal dystrophies involving the retinoid cycle.
Collapse
Affiliation(s)
- Ifat Sher
- Goldschleger Eye Institute, Sheba Medical Center, Tel-Hashomer, Israel
| | - Adi Tzameret
- Goldschleger Eye Institute, Sheba Medical Center, Tel-Hashomer, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Sara Peri-Chen
- Goldschleger Eye Institute, Sheba Medical Center, Tel-Hashomer, Israel
| | - Victoria Edelshtain
- Goldschleger Eye Institute, Sheba Medical Center, Tel-Hashomer, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Michael Ioffe
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Alon Sayer
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Ludmila Buzhansky
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.,BLAVATNIK CENTER for Drug Discovery, Tel Aviv University, Tel Aviv, Israel
| | - Ehud Gazit
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.,Department of Materials Science and Engineering, Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel.,BLAVATNIK CENTER for Drug Discovery, Tel Aviv University, Tel Aviv, Israel
| | - Ygal Rotenstreich
- Goldschleger Eye Institute, Sheba Medical Center, Tel-Hashomer, Israel. .,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
| |
Collapse
|
18
|
Gao S, Kahremany S, Zhang J, Jastrzebska B, Querubin J, Petersen-Jones SM, Palczewski K. Retinal-chitosan Conjugates Effectively Deliver Active Chromophores to Retinal Photoreceptor Cells in Blind Mice and Dogs. Mol Pharmacol 2018; 93:438-452. [PMID: 29453250 DOI: 10.1124/mol.117.111294] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 02/13/2018] [Indexed: 12/13/2022] Open
Abstract
The retinoid (visual) cycle consists of a series of biochemical reactions needed to regenerate the visual chromophore 11-cis-retinal and sustain vision. Genetic or environmental factors affecting chromophore production can lead to blindness. Using animal models that mimic human retinal diseases, we previously demonstrated that mechanism-based pharmacological interventions can maintain vision in otherwise incurable genetic diseases of the retina. Here, we report that after 9-cis-retinal administration to lecithin:retinol acyltransferase-deficient (Lrat-/- ) mice, the drug was rapidly absorbed and then cleared within 1 to 2 hours. However, when conjugated to form chitosan-9-cis-retinal, this prodrug was slowly absorbed from the gastrointestinal tract, resulting in sustainable plasma levels of 9-cis-retinol and recovery of visual function without causing elevated levels, as occurs with unconjugated drug treatment. Administration of chitosan-9-cis-retinal conjugate intravitreally in retinal pigment epithelium-specific 65 retinoid isomerase (RPE65)-deficient dogs improved photoreceptor function as assessed by electroretinography. Functional rescue was dose dependent and maintained for several weeks. Dosing via the gastrointestinal tract in canines was found ineffective, most likely due to peculiarities of vitamin A blood transport in canines. Use of the chitosan conjugate in combination with 11-cis-6-ring-retinal, a locked ring analog of 11-cis-retinal that selectively blocks rod opsin consumption of chromophore while largely sparing cone opsins, was found to prolong cone vision in Lrat-/- mice. Development of such combination low-dose regimens to selectively prolong useful cone vision could not only expand retinal disease treatments to include Leber congenital amaurosis but also the age-related decline in human dark adaptation from progressive retinoid cycle deficiency.
Collapse
Affiliation(s)
- Songqi Gao
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio (S.G., S.K., J.Z., B.J., K.P.) and Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan (J.Q., S.M.P.-J.)
| | - Shirin Kahremany
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio (S.G., S.K., J.Z., B.J., K.P.) and Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan (J.Q., S.M.P.-J.)
| | - Jianye Zhang
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio (S.G., S.K., J.Z., B.J., K.P.) and Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan (J.Q., S.M.P.-J.)
| | - Beata Jastrzebska
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio (S.G., S.K., J.Z., B.J., K.P.) and Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan (J.Q., S.M.P.-J.)
| | - Janice Querubin
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio (S.G., S.K., J.Z., B.J., K.P.) and Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan (J.Q., S.M.P.-J.)
| | - Simon M Petersen-Jones
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio (S.G., S.K., J.Z., B.J., K.P.) and Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan (J.Q., S.M.P.-J.)
| | - Krzysztof Palczewski
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio (S.G., S.K., J.Z., B.J., K.P.) and Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan (J.Q., S.M.P.-J.)
| |
Collapse
|
19
|
Scholl HPN, Strauss RW, Singh MS, Dalkara D, Roska B, Picaud S, Sahel JA. Emerging therapies for inherited retinal degeneration. Sci Transl Med 2017; 8:368rv6. [PMID: 27928030 DOI: 10.1126/scitranslmed.aaf2838] [Citation(s) in RCA: 147] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 11/17/2016] [Indexed: 12/13/2022]
Abstract
Inherited retinal degenerative diseases, a genetically and phenotypically heterogeneous group of disorders, affect the function of photoreceptor cells and are among the leading causes of blindness. Recent advances in molecular genetics and cell biology are elucidating the pathophysiological mechanisms underlying these disorders and are helping to identify new therapeutic approaches, such as gene therapy, stem cell therapy, and optogenetics. Several of these approaches have entered the clinical phase of development. Artificial replacement of dying photoreceptor cells using retinal prostheses has received regulatory approval. Precise retinal imaging and testing of visual function are facilitating more efficient clinical trial design. In individual patients, disease stage will determine whether the therapeutic strategy should comprise photoreceptor cell rescue to delay or arrest vision loss or retinal replacement for vision restoration.
Collapse
Affiliation(s)
- Hendrik P N Scholl
- Department of Ophthalmology, University of Basel, 4056 Basel, Switzerland. .,Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Rupert W Strauss
- Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD 21287, USA.,Moorfields Eye Hospital, London EC1V 2PD, U.K.,UCL Institute of Ophthalmology, University College London, London EC1V 9EL, U.K.,Department of Ophthalmology, Medical University Graz, Graz, Austria.,Department of Ophthalmology, Johannes Kepler University Linz, 4021 Linz, Austria
| | - Mandeep S Singh
- Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Deniz Dalkara
- INSERM, UMR S 968, 75012 Paris, France.,Sorbonne Universités, UPMC Univ Paris 06, Institut de la Vision, Paris, France.,CNRS, UMR 7210, 75012 Paris, France
| | - Botond Roska
- Department of Ophthalmology, University of Basel, 4056 Basel, Switzerland.,Neural Circuit Laboratories, Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Serge Picaud
- INSERM, UMR S 968, 75012 Paris, France.,Sorbonne Universités, UPMC Univ Paris 06, Institut de la Vision, Paris, France.,CNRS, UMR 7210, 75012 Paris, France
| | - José-Alain Sahel
- INSERM, UMR S 968, 75012 Paris, France.,Sorbonne Universités, UPMC Univ Paris 06, Institut de la Vision, Paris, France.,CNRS, UMR 7210, 75012 Paris, France.,Fondation Ophtalmologique Adolphe de Rothschild, 75019 Paris, France.,Centre d'Investigation Clinique 1423, INSERM-Center Hospitalier National d'Ophtalmologie des Quinze-Vingts, 75012 Paris, France.,Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| |
Collapse
|
20
|
Flavonoid allosteric modulation of mutated visual rhodopsin associated with retinitis pigmentosa. Sci Rep 2017; 7:11167. [PMID: 28894166 PMCID: PMC5593859 DOI: 10.1038/s41598-017-11391-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 08/22/2017] [Indexed: 11/08/2022] Open
Abstract
Dietary flavonoids exhibit many biologically-relevant functions and can potentially have beneficial effects in the treatment of pathological conditions. In spite of its well known antioxidant properties, scarce structural information is available on the interaction of flavonoids with membrane receptors. Advances in the structural biology of a specific class of membrane receptors, the G protein-coupled receptors, have significantly increased our understanding of drug action and paved the way for developing improved therapeutic approaches. We have analyzed the effect of the flavonoid quercetin on the conformation, stability and function of the G protein-coupled receptor rhodopsin, and the G90V mutant associated with the retinal degenerative disease retinitis pigmentosa. By using a combination of experimental and computational methods, we suggest that quercetin can act as an allosteric modulator of opsin regenerated with 9-cis-retinal and more importantly, that this binding has a positive effect on the stability and conformational properties of the G90V mutant associated with retinitis pigmentosa. These results open new possibilities to use quercetin and other flavonoids, in combination with specific retinoids like 9-cis-retinal, for the treatment of retinal degeneration associated with retinitis pigmentosa. Moreover, the use of flavonoids as allosteric modulators may also be applicable to other members of the G protein-coupled receptors superfamily.
Collapse
|
21
|
Chelstowska S, Widjaja-Adhi MAK, Silvaroli JA, Golczak M. Impact of LCA-Associated E14L LRAT Mutation on Protein Stability and Retinoid Homeostasis. Biochemistry 2017; 56:4489-4499. [PMID: 28758396 PMCID: PMC5682948 DOI: 10.1021/acs.biochem.7b00451] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Vitamin A (all-trans-retinol) is metabolized to the visual chromophore (11-cis-retinal) in the eyes and to all-trans-retinoic acid, a hormone like compound, in most tissues. A key enzyme in retinoid metabolism is lecithin:retinol acyltransferase (LRAT), which catalyzes the esterification of vitamin A. The importance of LRAT is indicated by pathogenic missense and nonsense mutations, which cause devastating blinding diseases. Retinoid-based chromophore replacement therapy has been proposed as treatment for these types of blindness based on studies in LRAT null mice. Here, we analyzed the structural and biochemical basis for retinal pathology caused by mutations in the human LRAT gene. Most LRAT missense mutations associated with retinal degeneration are localized within the catalytic domain, whereas E14L substitution is localized in an N-terminal α-helix, which has been implicated in interaction with the phospholipid bilayer. To elucidate the biochemical consequences of this mutation, we determined LRAT(E14L)'s enzymatic properties, protein stability, and impact on ocular retinoid metabolism. Bicistronic expression of LRAT(E14L) and enhanced green fluorescence protein revealed instability and accelerated proteosomal degradation of this mutant isoform. Surprisingly, instability of LRAT(E14L) did not abrogate the production of the visual chromophore in a cell-based assay. Instead, expression of LRAT(E14L) led to a rapid increase in cellular levels of retinoic acid upon retinoid supplementation. Thus, our study unveils the potential role of retinoic acid in the pathology of a degenerative retinal disease with important implications for the use of retinoid-based therapeutics in affected patients.
Collapse
Affiliation(s)
- Sylwia Chelstowska
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106, United States
- Laboratory of Hematology and Flow Cytometry, Department of Hematology, Military Institute of Medicine, Warsaw 04141, Poland
| | | | - Josie A. Silvaroli
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Marcin Golczak
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106, United States
- Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, United States
| |
Collapse
|
22
|
Kumaran N, Moore AT, Weleber RG, Michaelides M. Leber congenital amaurosis/early-onset severe retinal dystrophy: clinical features, molecular genetics and therapeutic interventions. Br J Ophthalmol 2017; 101:1147-1154. [PMID: 28689169 PMCID: PMC5574398 DOI: 10.1136/bjophthalmol-2016-309975] [Citation(s) in RCA: 195] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 04/26/2017] [Accepted: 04/30/2017] [Indexed: 12/29/2022]
Abstract
Leber congenital amaurosis (LCA) and early-onset severe retinal dystrophy (EOSRD) are both genetically and phenotypically heterogeneous, and characterised clinically by severe congenital/early infancy visual loss, nystagmus, amaurotic pupils and markedly reduced/absent full-field electroretinograms. The vast genetic heterogeneity of inherited retinal disease has been established over the last 10 - 20 years, with disease-causing variants identified in 25 genes to date associated with LCA/EOSRD, accounting for 70–80% of cases, with thereby more genes yet to be identified. There is now far greater understanding of the structural and functional associations seen in the various LCA/EOSRD genotypes. Subsequent development/characterisation of LCA/EOSRD animal models has shed light on the underlying pathogenesis and allowed the demonstration of successful rescue with gene replacement therapy and pharmacological intervention in multiple models. These advancements have culminated in more than 12 completed, ongoing and anticipated phase I/II and phase III gene therapy and pharmacological human clinical trials. This review describes the clinical and genetic characteristics of LCA/EOSRD and the differential diagnoses to be considered. We discuss in further detail the diagnostic clinical features, pathophysiology, animal models and human treatment studies and trials, in the more common genetic subtypes and/or those closest to intervention.
Collapse
Affiliation(s)
- Neruban Kumaran
- UCL Institute of Ophthalmology, University College London, London, UK.,Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Anthony T Moore
- UCL Institute of Ophthalmology, University College London, London, UK.,Moorfields Eye Hospital NHS Foundation Trust, London, UK.,University of California San Francisco, San Francisco CA, California, USA
| | - Richard G Weleber
- Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, USA
| | - Michel Michaelides
- UCL Institute of Ophthalmology, University College London, London, UK.,Moorfields Eye Hospital NHS Foundation Trust, London, UK
| |
Collapse
|
23
|
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.
Collapse
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
| |
Collapse
|
24
|
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.
Collapse
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
| |
Collapse
|
25
|
Abstract
Visual systems detect light by monitoring the effect of photoisomerization of a chromophore on the release of a neurotransmitter from sensory neurons, known as rod and cone photoreceptor cells in vertebrate retina. In all known visual systems, the chromophore is 11-cis-retinal complexed with a protein, called opsin, and photoisomerization produces all-trans-retinal. In mammals, regeneration of 11-cis-retinal following photoisomerization occurs by a thermally driven isomerization reaction. Additional reactions are required during regeneration to protect cells from the toxicity of aldehyde forms of vitamin A that are essential to the visual process. Photochemical and phototransduction reactions in rods and cones are identical; however, reactions of the rod and cone visual pigment regeneration cycles differ, and perplexingly, rod and cone regeneration cycles appear to use different mechanisms to overcome the energy barrier involved in converting all-trans- to 11-cis-retinoid. Abnormal processing of all-trans-retinal in the rod regeneration cycle leads to retinal degeneration, suggesting that excessive amounts of the retinoid itself or its derivatives are toxic. This line of reasoning led to the development of various approaches to modifying the activity of the rod visual cycle as a possible therapeutic approach to delay or prevent retinal degeneration in inherited retinal diseases and perhaps in the dry form of macular degeneration (geographic atrophy). In spite of great progress in understanding the functioning of rod and cone regeneration cycles at a molecular level, resolution of a number of remaining puzzling issues will offer insight into the amelioration of several blinding retinal diseases.
Collapse
|
26
|
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.
Collapse
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
| | | |
Collapse
|
27
|
Thierry M, Pasquis B, Buteau B, Fourgeux C, Dembele D, Leclere L, Gambert-Nicot S, Acar N, Bron AM, Creuzot-Garcher CP, Bretillon L. Early adaptive response of the retina to a pro-diabetogenic diet: Impairment of cone response and gene expression changes in high-fructose fed rats. Exp Eye Res 2015; 135:37-46. [PMID: 25912194 DOI: 10.1016/j.exer.2015.04.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Revised: 04/17/2015] [Accepted: 04/21/2015] [Indexed: 11/17/2022]
Abstract
The lack of plasticity of neurons to respond to dietary changes, such as high fat and high fructose diets, by modulating gene and protein expression has been associated with functional and behavioral impairments that can have detrimental consequences. The inhibition of high fat-induced rewiring of hypothalamic neurons induced obesity. Feeding rodents with high fructose is a recognized and widely used model to trigger obesity and metabolic syndrome. However the adaptive response of the retina to short term feeding with high fructose is poorly documented. We therefore aimed to characterize both the functional and gene expression changes in the neurosensory retina of Brown Norway rats fed during 3 and 8 days with a 60%-rich fructose diet (n = 16 per diet and per time point). Glucose, insulin, leptin, triacylglycerols, total cholesterol, HDL-cholesterol, LDL-cholesterol and fructosamine were quantified in plasma (n = 8 in each group). Functionality of the inner retina was studied using scotopic single flash electroretinography (n = 8 in each group) and the individual response of rod and cone photoreceptors was determined using 8.02 Hz Flicker electroretinography (n = 8 in each group). Analysis of gene expression in the neurosensory retina was performed by Affymetrix genechips, and confirmed by RT-qPCR (n = 6 in each group). Elevated glycemia (+13%), insulinemia (+83%), and leptinemia (+172%) was observed after 8 days of fructose feeding. The cone photoreceptor response was altered at day 8 in high fructose fed rats (Δ = 0.5 log unit of light stimulus intensity). Affymetrix analysis of gene expression highlighted significant modulation of the pathways of eIF2 signaling and endoplasmic reticulum stress, regulation of eIF4 and p70S6K signaling, as well as mTOR signaling and mitochondrial dysfunction. RT-qPCR analysis confirmed the down regulation of Crystallins, Npy, Nid1 and Optc genes after 3 days of fructose feeding, and up regulation of End2. Meanwhile, a trend towards an increased expression of αA- and αB-crystallin proteins was observed at day 8. Our results are consistent with early alterations of the functioning and gene expression in the retina in a pro diabetogenic environment.
Collapse
Affiliation(s)
- Magalie Thierry
- INRA, UMR1324 Centre des Sciences du Goût et de l'Alimentation, Eye and Nutrition Research Group, F-21000 Dijon, France; CNRS, UMR6265 Centre des Sciences du Goût et de l'Alimentation, F-21000 Dijon, France; Université de Bourgogne, Centre des Sciences du Goût et de l'Alimentation, F-21000 Dijon, France
| | - Bruno Pasquis
- INRA, UMR1324 Centre des Sciences du Goût et de l'Alimentation, Eye and Nutrition Research Group, F-21000 Dijon, France; CNRS, UMR6265 Centre des Sciences du Goût et de l'Alimentation, F-21000 Dijon, France; Université de Bourgogne, Centre des Sciences du Goût et de l'Alimentation, F-21000 Dijon, France
| | - Bénédicte Buteau
- INRA, UMR1324 Centre des Sciences du Goût et de l'Alimentation, Eye and Nutrition Research Group, F-21000 Dijon, France; CNRS, UMR6265 Centre des Sciences du Goût et de l'Alimentation, F-21000 Dijon, France; Université de Bourgogne, Centre des Sciences du Goût et de l'Alimentation, F-21000 Dijon, France
| | - Cynthia Fourgeux
- INRA, UMR1324 Centre des Sciences du Goût et de l'Alimentation, Eye and Nutrition Research Group, F-21000 Dijon, France; CNRS, UMR6265 Centre des Sciences du Goût et de l'Alimentation, F-21000 Dijon, France; Université de Bourgogne, Centre des Sciences du Goût et de l'Alimentation, F-21000 Dijon, France
| | - Doulaye Dembele
- INSERM, UMR964 Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), F-67404 Illkirch, France; CNRS, UMR7104 Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), F-67404 Illkirch, France; Université de Strasbourg, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), F-67404 Illkirch, France; IGBMC, Microarray and Sequencing Platform, F-67404 Illkirch, France
| | - Laurent Leclere
- INRA, UMR1324 Centre des Sciences du Goût et de l'Alimentation, Eye and Nutrition Research Group, F-21000 Dijon, France; CNRS, UMR6265 Centre des Sciences du Goût et de l'Alimentation, F-21000 Dijon, France; Université de Bourgogne, Centre des Sciences du Goût et de l'Alimentation, F-21000 Dijon, France
| | - Ségolène Gambert-Nicot
- INRA, UMR1324 Centre des Sciences du Goût et de l'Alimentation, Eye and Nutrition Research Group, F-21000 Dijon, France; CNRS, UMR6265 Centre des Sciences du Goût et de l'Alimentation, F-21000 Dijon, France; Université de Bourgogne, Centre des Sciences du Goût et de l'Alimentation, F-21000 Dijon, France; University Hospital, Department of Clinical Chemistry, F-21000 Dijon, France
| | - Niyazi Acar
- INRA, UMR1324 Centre des Sciences du Goût et de l'Alimentation, Eye and Nutrition Research Group, F-21000 Dijon, France; CNRS, UMR6265 Centre des Sciences du Goût et de l'Alimentation, F-21000 Dijon, France; Université de Bourgogne, Centre des Sciences du Goût et de l'Alimentation, F-21000 Dijon, France
| | - Alain M Bron
- INRA, UMR1324 Centre des Sciences du Goût et de l'Alimentation, Eye and Nutrition Research Group, F-21000 Dijon, France; CNRS, UMR6265 Centre des Sciences du Goût et de l'Alimentation, F-21000 Dijon, France; Université de Bourgogne, Centre des Sciences du Goût et de l'Alimentation, F-21000 Dijon, France; University Hospital, Department of Ophthalmology, F-21000 Dijon, France
| | - Catherine P Creuzot-Garcher
- INRA, UMR1324 Centre des Sciences du Goût et de l'Alimentation, Eye and Nutrition Research Group, F-21000 Dijon, France; CNRS, UMR6265 Centre des Sciences du Goût et de l'Alimentation, F-21000 Dijon, France; Université de Bourgogne, Centre des Sciences du Goût et de l'Alimentation, F-21000 Dijon, France; University Hospital, Department of Ophthalmology, F-21000 Dijon, France
| | - Lionel Bretillon
- INRA, UMR1324 Centre des Sciences du Goût et de l'Alimentation, Eye and Nutrition Research Group, F-21000 Dijon, France; CNRS, UMR6265 Centre des Sciences du Goût et de l'Alimentation, F-21000 Dijon, France; Université de Bourgogne, Centre des Sciences du Goût et de l'Alimentation, F-21000 Dijon, France.
| |
Collapse
|
28
|
Jacobson SG, Cideciyan AV, Aguirre GD, Roman AJ, Sumaroka A, Hauswirth WW, Palczewski K. Improvement in vision: a new goal for treatment of hereditary retinal degenerations. Expert Opin Orphan Drugs 2015; 3:563-575. [PMID: 26246977 PMCID: PMC4487613 DOI: 10.1517/21678707.2015.1030393] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Introduction: Inherited retinal degenerations (IRDs) have long been considered untreatable and incurable. Recently, one form of early-onset autosomal recessive IRD, Leber congenital amaurosis (LCA) caused by mutations in RPE65 (retinal pigment epithelium-specific protein 65 kDa) gene, has responded with some improvement of vision to gene augmentation therapy and oral retinoid administration. This early success now requires refinement of such therapeutics to fully realize the impact of these major scientific and clinical advances. Areas covered: Progress toward human therapy for RPE65-LCA is detailed from the understanding of molecular mechanisms to preclinical proof-of-concept research to clinical trials. Unexpected positive and complicating results in the patients receiving treatment are explained. Logical next steps to advance the clinical value of the therapeutics are suggested. Expert opinion: The first molecularly based early-phase therapies for an IRD are remarkably successful in that vision has improved and adverse events are mainly associated with surgical delivery to the subretinal space. Yet, there are features of the gene augmentation therapeutic response, such as slowed kinetics of night vision, lack of foveal cone function improvement and relentlessly progressive retinal degeneration despite therapy, that still require research attention.
Collapse
Affiliation(s)
- Samuel G Jacobson
- University of Pennsylvania, Scheie Eye Institute, Perelman School of Medicine, Department of Ophthalmology , Philadelphia, PA, USA
| | - Artur V Cideciyan
- University of Pennsylvania, Scheie Eye Institute, Perelman School of Medicine, Department of Ophthalmology , Philadelphia, PA, USA
| | - Gustavo D Aguirre
- University of Pennsylvania, School of Veterinary Medicine, Section of Ophthalmology , Philadelphia, PA, USA
| | - Alejandro J Roman
- University of Pennsylvania, Scheie Eye Institute, Perelman School of Medicine, Department of Ophthalmology , Philadelphia, PA, USA
| | - Alexander Sumaroka
- University of Pennsylvania, Scheie Eye Institute, Perelman School of Medicine, Department of Ophthalmology , Philadelphia, PA, USA
| | | | - Krzysztof Palczewski
- Case Western University, School of Medicine, Cleveland Center for Membrane and Structural Biology, Department of Pharmacology , Cleveland, OH, USA
| |
Collapse
|
29
|
Perusek L, Maeda A, Maeda T. Supplementation with vitamin a derivatives to rescue vision in animal models of degenerative retinal diseases. Methods Mol Biol 2015; 1271:345-362. [PMID: 25697534 DOI: 10.1007/978-1-4939-2330-4_22] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The perception of light begins when photons reach retinal tissue located at the back of the eye and photoisomerize the visual chromophore 11-cis-retinal to all-trans-retinal within photoreceptor cells. Isomerization of 11-cis-retinal activates the protein rhodopsin located in photoreceptor outer segments, thereby inducing a phototransduction cascade leading to visual perception. To maintain vision, 11-cis-retinal is regenerated in the retinal pigmented epithelium (RPE) via the visual cycle and delivered back to the photoreceptor cells where it may again bind to rhodopsin. Distinct pathological mechanisms have been observed to contribute to inherited retinal degenerative diseases including severe delay in 11-cis-retinal regeneration and delayed clearance of all-trans-retinal, which leads to the accumulation of harmful retinoid by-products. In the last decade, our group has conducted several proof-of-concept (POC) studies with retinoid derivatives aimed at developing treatments for retinal degenerative diseases caused by an impaired visual cycle. Here, we will introduce experimental procedures, which have been developed for POC studies involving retinoid biology.
Collapse
Affiliation(s)
- Lindsay Perusek
- Department of Ophthalmology and Visual Sciences, School of Medicine, Case Western Reserve University, Adelbert Road 2085, Cleveland, OH, 44106, USA
| | | | | |
Collapse
|
30
|
Koenekoop RK, Sui R, Sallum J, van den Born LI, Ajlan R, Khan A, den Hollander AI, Cremers FPM, Mendola JD, Bittner AK, Dagnelie G, Schuchard RA, Saperstein DA. Oral 9-cis retinoid for childhood blindness due to Leber congenital amaurosis caused by RPE65 or LRAT mutations: an open-label phase 1b trial. Lancet 2014; 384:1513-20. [PMID: 25030840 DOI: 10.1016/s0140-6736(14)60153-7] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Leber congenital amaurosis, caused by mutations in RPE65 and LRAT, is a severe form of inherited retinal degeneration leading to blindness. We aimed to assess replacement of the missing chromophore 11-cis retinal with oral QLT091001 (synthetic 9-cis-retinyl acetate) in these patients. METHODS In our open-label, prospective, phase 1b trial, we enrolled patients (aged ≥6 years) with Leber congenital amaurosis and RPE65 or LRAT mutations at McGill University's Montreal Children's Hospital. Patients received 7 days of oral QLT091001 (10-40 mg/m(2) per day). We assessed patients at baseline and days 7, 9, 14, and 30, and then 2 months and every 2 months thereafter for up to 2·2 years for safety outcomes and visual function endpoints including Goldmann visual fields (GVF), visual acuity, and functional MRI assessment. We regarded patients as having an improvement in vision if we noted at least a 20% improvement in retinal area on GVF compared with baseline or a visual acuity improvement of five or more letters compared with baseline in two consecutive study visits (or any improvement from no vision at baseline). This study is registered with ClinicalTrials.gov, number NCT01014052. FINDINGS Between December, 2009, and June, 2011, we enrolled and treated 14 patients aged 6-38 years who were followed up until March, 2012. Ten (71%) of 14 patients had an improvement in GVF areas (mean increase in retinal area of 28-683%). Six (43%) patients had an improvement in visual acuity (mean increase of 2-30 letters). Self-reported or parent-reported improvements in activities of daily living supported these findings. After 2 years, 11 (79%) patients had returned to their baseline GVF retinal area and ten (71%) had returned to baseline visual acuity letter values. Thus, three (21%) patients had a sustained GVF response and four (30%) had a sustained visual acuity response. Four patients had functional MRI scans, which correlated with visual response or absence of response to treatment. No serious adverse events occurred, although we noted transient headaches (11 patients), photophobia (11 patients), reduction in serum HDL concentrations (four patients), and increases in serum triglycerides (eight patients) and aspartate aminotransferase concentrations (two patients). INTERPRETATION Non-invasive oral QLT091001 therapy is well tolerated, and can rapidly improve visual function in some patients with Leber congenital amaurosis and RPE65 and LRAT mutations. FUNDING QLT, Foundation Fighting Blindness Canada, CIHR, FRSQ, Reseau Vision.
Collapse
Affiliation(s)
- Robert K Koenekoop
- McGill Ocular Genetics Laboratory and Paediatric Ophthalmology, Montreal Children's Hospital, Departments of Paediatric Surgery, Human Genetics and Ophthalmology, McGill University Health Centre, Montreal, Quebec, Canada.
| | - Ruifang Sui
- Ophthalmology, Peking Union Medical College Hospital, Beijing, China
| | - Juliana Sallum
- Ophthalmology, Federal University of São Paulo, São Paulo, Brazil
| | | | - Radwan Ajlan
- McGill Ocular Genetics Laboratory and Paediatric Ophthalmology, Montreal Children's Hospital, Departments of Paediatric Surgery, Human Genetics and Ophthalmology, McGill University Health Centre, Montreal, Quebec, Canada
| | - Ayesha Khan
- McGill Ocular Genetics Laboratory and Paediatric Ophthalmology, Montreal Children's Hospital, Departments of Paediatric Surgery, Human Genetics and Ophthalmology, McGill University Health Centre, Montreal, Quebec, Canada
| | - Anneke I den Hollander
- Department of Ophthalmology, Department of Human Genetics and Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - Frans P M Cremers
- Department of Human Genetics and Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - Janine D Mendola
- McGill Vision Research Unit and Department of Ophthalmology, McGill University Health Centre, Montreal, Quebec, Canada
| | - Ava K Bittner
- The Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Gislin Dagnelie
- The Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA
| | | | | |
Collapse
|
31
|
Palczewski K. Chemistry and biology of the initial steps in vision: the Friedenwald lecture. Invest Ophthalmol Vis Sci 2014; 55:6651-72. [PMID: 25338686 DOI: 10.1167/iovs.14-15502] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Visual transduction is the process in the eye whereby absorption of light in the retina is translated into electrical signals that ultimately reach the brain. The first challenge presented by visual transduction is to understand its molecular basis. We know that maintenance of vision is a continuous process requiring the activation and subsequent restoration of a vitamin A-derived chromophore through a series of chemical reactions catalyzed by enzymes in the retina and retinal pigment epithelium (RPE). Diverse biochemical approaches that identified key proteins and reactions were essential to achieve a mechanistic understanding of these visual processes. The three-dimensional arrangements of these enzymes' polypeptide chains provide invaluable insights into their mechanisms of action. A wealth of information has already been obtained by solving high-resolution crystal structures of both rhodopsin and the retinoid isomerase from pigment RPE (RPE65). Rhodopsin, which is activated by photoisomerization of its 11-cis-retinylidene chromophore, is a prototypical member of a large family of membrane-bound proteins called G protein-coupled receptors (GPCRs). RPE65 is a retinoid isomerase critical for regeneration of the chromophore. Electron microscopy (EM) and atomic force microscopy have provided insights into how certain proteins are assembled to form much larger structures such as rod photoreceptor cell outer segment membranes. A second challenge of visual transduction is to use this knowledge to devise therapeutic approaches that can prevent or reverse conditions leading to blindness. Imaging modalities like optical coherence tomography (OCT) and scanning laser ophthalmoscopy (SLO) applied to appropriate animal models as well as human retinal imaging have been employed to characterize blinding diseases, monitor their progression, and evaluate the success of therapeutic agents. Lately two-photon (2-PO) imaging, together with biochemical assays, are revealing functional aspects of vision at a new molecular level. These multidisciplinary approaches combined with suitable animal models and inbred mutant species can be especially helpful in translating provocative cell and tissue culture findings into therapeutic options for further development in animals and eventually in humans. A host of different approaches and techniques is required for substantial progress in understanding fundamental properties of the visual system.
Collapse
Affiliation(s)
- Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States
| |
Collapse
|
32
|
Babino D, Perkins BD, Kindermann A, Oberhauser V, von Lintig J. The role of 11-cis-retinyl esters in vertebrate cone vision. FASEB J 2014; 29:216-26. [PMID: 25326538 DOI: 10.1096/fj.14-261693] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A cycle of cis-to-trans isomerization of the chromophore is intrinsic to vertebrate vision where rod and cone photoreceptors mediate dim- and bright-light vision, respectively. Daylight illumination can greatly exceed the rate at which the photoproduct can be recycled back to the chromophore by the canonical visual cycle. Thus, an additional supply pathway(s) must exist to sustain cone-dependent vision. Two-photon microscopy revealed that the eyes of the zebrafish (Danio rerio) contain high levels of 11-cis-retinyl esters (11-REs) within the retinal pigment epithelium. HPLC analyses demonstrate that 11-REs are bleached by bright light and regenerated in the dark. Pharmacologic treatment with all-trans-retinylamine (Ret-NH2), a potent and specific inhibitor of the trans-to-cis reisomerization reaction of the canonical visual cycle, impeded the regeneration of 11-REs. Intervention with 11-cis-retinol restored the regeneration of 11-REs in the presence of all-trans-Ret-NH2. We used the XOPS:mCFP transgenic zebrafish line with a functional cone-only retina to directly demonstrate that this 11-RE cycle is critical to maintain vision under bright-light conditions. Thus, our analyses reveal that a dark-generated pool of 11-REs helps to supply photoreceptors with the chromophore under the varying light conditions present in natural environments.
Collapse
Affiliation(s)
- Darwin Babino
- Department of Pharmacology, Case School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Brian D Perkins
- Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio, USA; and
| | - Aljoscha Kindermann
- Albert-Ludwigs Universität Freiburg, Institut für Biologie I, Neurobiologie und Tiephysiologie, Freiburg, Germany
| | - Vitus Oberhauser
- Albert-Ludwigs Universität Freiburg, Institut für Biologie I, Neurobiologie und Tiephysiologie, Freiburg, Germany
| | - Johannes von Lintig
- Department of Pharmacology, Case School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA;
| |
Collapse
|
33
|
Ozaki T, Nakazawa M, Kudo T, Hirano S, Suzuki K, Ishiguro SI. Protection of Cone Photoreceptor M-Opsin Degradation with 9-Cis-β-Carotene-Rich AlgaDunaliella bardawilinRpe65−/−Mouse Retinal Explant Culture. Curr Eye Res 2014; 39:1221-31. [DOI: 10.3109/02713683.2014.907430] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
|
34
|
Two-photon microscopy reveals early rod photoreceptor cell damage in light-exposed mutant mice. Proc Natl Acad Sci U S A 2014; 111:E1428-37. [PMID: 24706832 DOI: 10.1073/pnas.1317986111] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Atrophic age-related and juvenile macular degeneration are especially devastating due to lack of an effective cure. Two retinal cell types, photoreceptor cells and the adjacent retinal pigmented epithelium (RPE), reportedly display the earliest pathological changes. Abca4(-/-)Rdh8(-/-) mice, which mimic many features of human retinal degeneration, allowed us to determine the sequence of light-induced events leading to retinal degeneration. Using two-photon microscopy with 3D reconstruction methodology, we observed an initial strong retinoid-derived fluorescence and expansion of Abca4(-/-)Rdh8(-/-) mouse rod cell outer segments accompanied by macrophage infiltration after brief exposure of the retina to bright light. Additionally, light-dependent fluorescent compounds produced in rod outer segments were not transferred to the RPE of mice genetically defective in RPE phagocytosis. Collectively, these findings suggest that for light-induced retinopathies in mice, rod photoreceptors are the primary site of toxic retinoid accumulation and degeneration, followed by secondary changes in the RPE.
Collapse
|
35
|
Affiliation(s)
| | | | - Krzysztof Palczewski
- Department of Pharmacology, School of Medicine, Case
Western Reserve University, 2109 Adelbert Road, Cleveland, Ohio 44106-4965,
United States
| |
Collapse
|
36
|
Koirala A, Conley SM, Makkia R, Liu Z, Cooper MJ, Sparrow JR, Naash MI. Persistence of non-viral vector mediated RPE65 expression: case for viability as a gene transfer therapy for RPE-based diseases. J Control Release 2013; 172:745-52. [PMID: 24035979 DOI: 10.1016/j.jconrel.2013.08.299] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 08/22/2013] [Indexed: 11/25/2022]
Abstract
Mutations in the retinal pigment epithelium (RPE) gene RPE65 are associated with multiple blinding diseases including Leber's Congenital Amaurosis (LCA). Our goal has been to develop persistent, effective non-viral genetic therapies to treat this condition. Using precisely engineered DNA vectors and high capacity compacted DNA nanoparticles (NP), we previously demonstrated that both plasmid and NP forms of VMD2-hRPE65-S/MAR improved the disease phenotypes in an rpe65(-/-) model of LCA up to 6 months post-injection (PI), however the duration of this treatment efficacy was not established. Here, we test the ability of these vectors to sustain gene expression and phenotypic improvement for the life of the animal. NPs or naked DNA were subretinally injected in rpe65(-/-) mice at postnatal day (P) 16 and evaluated at 15 months PI. Quantitative real-time PCR (qRT-PCR) and immunofluorescence were performed at PI-15 months and demonstrated appreciable expression of transferred RPE65 (levels were 32% of wild-type [WT] for NPs and 44% of WT for naked DNA). No reduction in expression at the message level was observed from PI-6 month data. Spectral electroretinography (ERG) demonstrated significant improvement in cone ERG amplitudes in treated versus uninjected animals. Most importantly, we also observed reduced fundus autofluorescence in the eyes injected with NP and naked DNA compared to uninjected counterparts. Consistent with these observations, biochemical studies showed a reduction in the accumulation of toxic retinyl esters in treated mice, suggesting that the transferred hRPE65 was functional. These critical results indicate that both NP and uncompacted plasmid VMD2-hRPE65-S/MAR can mediate persistent, long-term improvement in an RPE-associated disease phenotype, and suggest that DNA NPs, which are non-toxic and have a large payload capacity, expand the treatment repertoire available for ocular gene therapy.
Collapse
Affiliation(s)
- Adarsha Koirala
- Department of Cell Biology, University of Oklahoma Health Sciences Center, 940 Stanton L. Young Boulevard, BMSB 781, Oklahoma City, OK 73104, USA
| | | | | | | | | | | | | |
Collapse
|
37
|
Wright CB, Chrenek MA, Foster SL, Duncan T, Redmond TM, Pardue MT, Boatright JH, Nickerson JM. Complementation test of Rpe65 knockout and tvrm148. Invest Ophthalmol Vis Sci 2013; 54:5111-22. [PMID: 23778877 DOI: 10.1167/iovs.13-12336] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE A mouse mutation, tvrm148, was previously reported as resulting in retinal degeneration. Tvrm148 and Rpe65 map between markers D3Mit147 and D3Mit19 on a genetic map, but the physical map places RPE65 outside the markers. We asked if Rpe65 or perhaps another nearby gene is mutated and if the mutant reduced 11-cis-retinal levels. We studied the impact of the tvrm148 mutation on visual function, morphology, and retinoid levels. METHODS Normal phase HPLC was used to measure retinoid levels. Rpe65(+/+), tvrm148/+ (T(+/-)), tvrm148/tvrm148 (T(-/-)), RPE65(KO/KO) (Rpe65(-/-)), and Rpe65(T/-) mice visual function was measured by optokinetic tracking (OKT) and electroretinography (ERG). Morphology was assessed by light microscopy and transmission electron microscopy (TEM). qRT-PCR was used to measure Rpe65 mRNA levels. Immunoblotting measured the size and amount of RPE65 protein. RESULTS The knockout and tvrm148 alleles did not complement. No 11-cis-retinal was detected in T(-/-) or Rpe65(-/-) mice. Visual acuity in Rpe65(+/+) and T(+/-) mouse was -0.382 c/d, but 0.037 c/d in T(-/-) mice at postnatal day 210 (P210). ERG response in T(-/-) mice was undetectable except at bright flash intensities. Outer nuclear layer (ONL) thickness in T(-/-) mice was -70% of Rpe65(+/+) by P210. Rpe65 mRNA levels in T(-/-) mice were unchanged, yet 14.5% of Rpe65(+/+) protein levels was detected. Protein size was unchanged. CONCLUSIONS A complementation test revealed the RPE65 knockout and tvrm148 alleles do not complement, proving that the tvrm148 mutation is in Rpe65. Behavioral, physiological, molecular, biochemical, and histological approaches indicate that tvrm148 is a null allele of Rpe65.
Collapse
Affiliation(s)
- Charles B Wright
- Department of Ophthalmology, School of Medicine, Emory University, Atlanta, Georgia 30322, USA
| | | | | | | | | | | | | | | |
Collapse
|
38
|
Vitamin A derivatives as treatment options for retinal degenerative diseases. Nutrients 2013; 5:2646-66. [PMID: 23857173 PMCID: PMC3738993 DOI: 10.3390/nu5072646] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 06/05/2013] [Accepted: 06/13/2013] [Indexed: 11/17/2022] Open
Abstract
The visual cycle is a sequential enzymatic reaction for vitamin A, all-trans-retinol, occurring in the outer layer of the human retina and is essential for the maintenance of vision. The central source of retinol is derived from dietary intake of both retinol and pro-vitamin A carotenoids. A series of enzymatic reactions, located in both the photoreceptor outer segment and the retinal pigment epithelium, transform retinol into the visual chromophore 11-cis-retinal, regenerating visual pigments. Retina specific proteins carry out the majority of the visual cycle, and any significant interruption in this sequence of reactions is capable of causing varying degrees of blindness. Among these important proteins are Lecithin:retinol acyltransferase (LRAT) and retinal pigment epithelium-specific 65-kDa protein (RPE65) known to be responsible for esterification of retinol to all-trans-retinyl esters and isomerization of these esters to 11-cis-retinal, respectively. Deleterious mutations in these genes are identified in human retinal diseases that cause blindness, such as Leber congenital amaurosis (LCA) and retinitis pigmentosa (RP). Herein, we discuss the pathology of 11-cis-retinal deficiency caused by these mutations in both animal disease models and human patients. We also review novel therapeutic strategies employing artificial visual chromophore 9-cis-retinoids which have been employed in clinical trials involving LCA patients.
Collapse
|
39
|
Koirala A, Conley SM, Naash MI. A review of therapeutic prospects of non-viral gene therapy in the retinal pigment epithelium. Biomaterials 2013; 34:7158-67. [PMID: 23796578 DOI: 10.1016/j.biomaterials.2013.06.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Accepted: 06/02/2013] [Indexed: 10/26/2022]
Abstract
Ocular gene therapy has been extensively explored in recent years as a therapeutic avenue to target diseases of the cornea, retina and retinal pigment epithelium (RPE). Adeno-associated virus (AAV)-mediated gene therapy has shown promise in several RPE clinical trials but AAVs have limited payload capacity and potential immunogenicity. Traditionally however, non-viral alternatives have been plagued by low transfection efficiency, short-term expression and low expression levels. Recently, these drawbacks have begun to be overcome by the use of specialty carriers such as polylysine, liposomes, or polyethyleneimines, and by inclusion of suitable DNA elements to enhance gene expression and longevity. Recent advancements in the field have yielded non-viral vectors that have favorable safety profiles, lack immunogenicity, exhibit long-term elevated gene expression, and show efficient transfection in the retina and RPE, making them poised to transition to clinical applications. Here we discuss the advancements in nanotechnology and vector engineering that have improved the prospects for clinical application of non-viral gene therapy in the RPE.
Collapse
Affiliation(s)
- Adarsha Koirala
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | | | | |
Collapse
|
40
|
Kawamura S, Gerstung M, Colozo AT, Helenius J, Maeda A, Beerenwinkel N, Park PSH, Müller DJ. Kinetic, energetic, and mechanical differences between dark-state rhodopsin and opsin. Structure 2013; 21:426-37. [PMID: 23434406 DOI: 10.1016/j.str.2013.01.011] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2012] [Revised: 01/05/2013] [Accepted: 01/15/2013] [Indexed: 11/20/2022]
Abstract
Rhodopsin, the photoreceptor pigment of the retina, initiates vision upon photon capture by its covalently linked chromophore 11-cis-retinal. In the absence of light, the chromophore serves as an inverse agonist locking the receptor in the inactive dark state. In the absence of chromophore, the apoprotein opsin shows low-level constitutive activity. Toward revealing insight into receptor properties controlled by the chromophore, we applied dynamic single-molecule force spectroscopy to quantify the kinetic, energetic, and mechanical differences between dark-state rhodopsin and opsin in native membranes from the retina of mice. Both rhodopsin and opsin are stabilized by ten structural segments. Compared to dark-state rhodopsin, the structural segments stabilizing opsin showed higher interaction strengths and mechanical rigidities and lower conformational variabilities, lifetimes, and free energies. These changes outline a common mechanism toward activating G-protein-coupled receptors. Additionally, we detected that opsin was more pliable and frequently stabilized alternate structural intermediates.
Collapse
Affiliation(s)
- Shiho Kawamura
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland
| | | | | | | | | | | | | | | |
Collapse
|
41
|
Boye SE, Boye SL, Lewin AS, Hauswirth WW. A comprehensive review of retinal gene therapy. Mol Ther 2013; 21:509-19. [PMID: 23358189 DOI: 10.1038/mt.2012.280] [Citation(s) in RCA: 204] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Blindness, although not life threatening, is a debilitating disorder for which few, if any treatments exist. Ocular gene therapies have the potential to profoundly improve the quality of life in patients with inherited retinal disease. As such, tremendous focus has been given to develop such therapies. Several factors make the eye an ideal organ for gene-replacement therapy including its accessibility, immune privilege, small size, compartmentalization, and the existence of a contralateral control. This review will provide a comprehensive summary of (i) existing gene therapy clinical trials for several genetic forms of blindness and (ii) preclinical efficacy and safety studies in a variety of animal models of retinal disease which demonstrate strong potential for clinical application. To be as comprehensive as possible, we include additional proof of concept studies using gene replacement, neurotrophic/neuroprotective, optogenetic, antiangiogenic, or antioxidative stress strategies as well as a description of the current challenges and future directions in the ocular gene therapy field to this review as a supplement.
Collapse
Affiliation(s)
- Shannon E Boye
- Department of Ophthalmology, University of Florida, Gainesville, FL, USA.
| | | | | | | |
Collapse
|
42
|
Maeda T, Dong Z, Jin H, Sawada O, Gao S, Utkhede D, Monk W, Palczewska G, Palczewski K. QLT091001, a 9-cis-retinal analog, is well-tolerated by retinas of mice with impaired visual cycles. Invest Ophthalmol Vis Sci 2013; 54:455-66. [PMID: 23249702 DOI: 10.1167/iovs.12-11152] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
PURPOSE Investigate whether retinas of mice with impaired retinal cycles exposed to light or kept in the dark tolerate prolonged high-dose administration of QLT091001, which contains as an active ingredient, the 9-cis-retinal precursor, 9-cis-retinyl acetate. METHODS Four- to six-week-old Lrat(-/-) and Rpe65(-/-) mice (n = 126) as well as crossbred Gnat1(-/-) mice lacking rod phototransduction (n = 110) were gavaged weekly for 6 months with 50 mg/kg QLT091001, either after being kept in the dark or after light bleaching for 30 min/wk followed by maintenance in a 12-hour light ≤ 10 lux)/12-hour dark cycle. Retinal health was monitored by spectral-domain optical coherent tomography (SD-OCT) and scanning laser ophthalmoscopy (SLO) every other month and histological, biochemical, and visual functional analyses were performed at the end of the experiment. Two-photon microscopy (TPM) was used to observe retinoid-containing retinosome structures in the RPE. RESULTS Retinal thickness and morphology examined by SD-OCT were well maintained in all strains treated with QLT091001. No significant increases of fundus autofluorescence were detected by SLO imaging of any strain. Accumulation of all-trans-retinyl esters varied with genetic background, types of administered compounds and lighting conditions but retinal health was not compromised. TPM imaging clearly revealed maintenance of retinosomes in the RPE of all mouse strains tested. CONCLUSIONS Retinas of Lrat(-/-), Rpe65(-/-), and crossbred Gnat1(-/-) mice tolerated prolonged high-dose QLT091001 treatment well.
Collapse
Affiliation(s)
- Tadao Maeda
- Department of Ophthalmology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
43
|
Falsini B, Bush RA, Sieving PA. Neuroprotection. Retina 2013. [DOI: 10.1016/b978-1-4557-0737-9.00037-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
44
|
Gao SQ, Maeda T, Okano K, Palczewski K. A microparticle/hydrogel combination drug-delivery system for sustained release of retinoids. Invest Ophthalmol Vis Sci 2012; 53:6314-23. [PMID: 22918645 PMCID: PMC3465014 DOI: 10.1167/iovs.12-10279] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2012] [Revised: 07/18/2012] [Accepted: 08/20/2012] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To design and develop a drug-delivery system containing a combination of poly(D,L-lactide-co-glycolide) (PLGA) microparticles and alginate hydrogel for sustained release of retinoids to treat retinal blinding diseases that result from an inadequate supply of retinol and generation of 11-cis-retinal. METHODS To study drug release in vivo, either the drug-loaded microparticle-hydrogel combination was injected subcutaneously or drug-loaded microparticles were injected intravitreally into Lrat(-/-) mice. Orally administered 9-cis-retinoids were used for comparison and drug concentrations in plasma were determined by HPLC. Electroretinography (ERG) and both chemical and histologic analyses were used to evaluate drug effects on visual function and morphology. RESULTS Lrat(-/-) mice demonstrated sustained drug release from the microparticle/hydrogel combination that lasted 4 weeks after subcutaneous injection. Drug concentrations in plasma of the control group treated with the same oral dose rose to higher levels for 6-7 hours but then dropped markedly by 24 hours. Significantly increased ERG responses and a markedly improved retinal pigmented epithelium (RPE)-rod outer segment (ROS) interface were observed after subcutaneous injection of the drug-loaded delivery combination. Intravitreal injection of just 2% of the systemic dose of drug-loaded microparticles provided comparable therapeutic efficacy. CONCLUSIONS Sustained release of therapeutic levels of 9-cis-retinoids was achieved in Lrat(-/-) mice by subcutaneous injection in a microparticle/hydrogel drug-delivery system. Both subcutaneous and intravitreal injections of drug-loaded microparticles into Lrat(-/-) mice improved visual function and retinal structure.
Collapse
Affiliation(s)
| | - Tadao Maeda
- Ophthalmology, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Kiichiro Okano
- Ophthalmology, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | | |
Collapse
|
45
|
Sahni JN, Angi M, Irigoyen C, Semeraro F, Romano MR, Parmeggiani F. Therapeutic challenges to retinitis pigmentosa: from neuroprotection to gene therapy. Curr Genomics 2012; 12:276-84. [PMID: 22131873 PMCID: PMC3131735 DOI: 10.2174/138920211795860062] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 04/08/2011] [Accepted: 04/18/2011] [Indexed: 12/12/2022] Open
Abstract
Syndromic retinitis pigmentosa (RP) is the result of several mutations expressed in rod photoreceptors, over 40 of which have so far been identified. Enormous efforts are being made to relate the advances in unraveling the patho-physiological mechanisms to therapeutic approaches in animal models, and eventually in clinical trials on humans. This review summarizes briefly the current clinical management of RP and focuses on the new exciting treatment possibilities. To date, there is no approved therapy able to stop the evolution of RP or restore vision. The current management includes an attempt at slowing down the degenerative process by vitamin supplementation, trying to treat ocular complications and to provide psychological support to blind patients. Novel therapeutic may be tailored dependant on the stage of the disease and can be divided in three groups. In the early stages, when there are surviving photoreceptors, the first approach would be to try to halt the degeneration by correction of the underlying biochemical abnormality in the visual cycle using gene therapy or pharmacological treatment. A second approach aims to cope with photoreceptor cell death using neurotrophic growth factors or anti-apoptotic factors, reducing the production of retino-toxic molecules, and limiting oxidative damage. In advanced stages, when there are few or no functional photoreceptors, strategies that may benefit include retinal transplantation, electronic retinal implants or a newly described optogenetic technique using a light-activated channel to genetically resensitize remnant cone-photoreceptor cells.
Collapse
Affiliation(s)
- Jayashree N Sahni
- St. Paul's Eye Unit, Royal Liverpool University Hospital, Liverpool, UK
| | | | | | | | | | | |
Collapse
|
46
|
Sato K, Ozaki T, Ishiguro SI, Nakazawa M. M-opsin protein degradation is inhibited by MG-132 in Rpe65⁻/⁻ retinal explant culture. Mol Vis 2012; 18:1516-25. [PMID: 22736942 PMCID: PMC3380917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Accepted: 06/08/2012] [Indexed: 12/05/2022] Open
Abstract
PURPOSE The 65 kDa retinal pigment epithelium-specific protein, RPE65, is an essential enzyme for 11-cis-retinal synthesis in the eye. Mutations of the RPE65 gene in humans result in severe vision loss, and Rpe65(-/-) mice show early cone photoreceptor degeneration. We used an explant culture system to evaluate whether posttranslational downregulation of M-opsin protein in Rpe65(-/-) mice is caused by proteolytic degradation. METHODS The eyes of three-week-old Rpe65(-/-) mice were incubated in culture medium. Western blot analysis was used to evaluate the level of M-opsin protein, and immunofluorescence was used for protein localization. The transcriptional level of M-opsin was evaluated with real-time reverse-transcriptase-PCR. RESULTS Degradation of the M-opsin protein in Rpe65(-/-) mouse retina was inhibited by the proteasome inhibitor MG-132 but not by the lysosomal inhibitor pepstatin A and E64d. 9-cis-retinal, used as an analog of 11-cis-retinal, increased M-opsin protein but did not increase M-opsin mRNA. Moreover, 9-cis-retinal did not change the transcriptional levels of photoreceptor specific genes. CONCLUSIONS Our data suggest that M-opsin protein was degraded through a proteasome pathway and that M-opsin degradation was suppressed with 9-cis-retinal treatment in Rpe65(-/-) mice to some extent.
Collapse
Affiliation(s)
- Kota Sato
- Department of Ophthalmology, Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan,Department of Biochemistry and Biotechnology, Division of Cell Technology, Hirosaki University Faculty of Agriculture and Life Science, Hirosaki, Aomori, Japan
| | - Taku Ozaki
- Department of Ophthalmology, Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan,Department of Biochemistry and Biotechnology, Division of Cell Technology, Hirosaki University Faculty of Agriculture and Life Science, Hirosaki, Aomori, Japan
| | - Sei-ichi Ishiguro
- Department of Biochemistry and Biotechnology, Division of Cell Technology, Hirosaki University Faculty of Agriculture and Life Science, Hirosaki, Aomori, Japan
| | - Mitsuru Nakazawa
- Department of Ophthalmology, Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan
| |
Collapse
|
47
|
|
48
|
Abstract
Visual perception in humans occurs through absorption of electromagnetic radiation from 400 to 780 nm by photoreceptors in the retina. A photon of visible light carries a sufficient amount of energy to cause, when absorbed, a cis,trans-geometric isomerization of the 11-cis-retinal chromophore, a vitamin A derivative bound to rhodopsin and cone opsins of retinal photoreceptors. The unique biochemistry of these complexes allows us to reliably and reproducibly collect continuous visual information about our environment. Moreover, other nonconventional retinal opsins such as the circadian rhythm regulator melanopsin also initiate light-activated signaling based on similar photochemistry.
Collapse
Affiliation(s)
- Krzysztof Palczewski
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106, USA.
| |
Collapse
|
49
|
Stein L, Roy K, Lei L, Kaushal S. Clinical gene therapy for the treatment of RPE65-associated Leber congenital amaurosis. Expert Opin Biol Ther 2011; 11:429-39. [PMID: 21299439 DOI: 10.1517/14712598.2011.557358] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION The positive results of pioneering clinical trials using gene therapy as treatment for patients with Leber congenital amaurosis (LCA) have ushered in a new era of molecular retinal therapeutics for LCA, other blinding retinal disorders and gene therapy applications. AREAS COVERED This review describes the role of retinal pigment epithelium-specific 65 kDa protein (RPE65) in the visual cycle and how RPE65 deficiency results in LCA; the extensive preclinical studies with recombinant adeno-associated virus (rAAV)-RPE65 gene vectors; and the human rAAV-RPE65 and related gene therapy clinical trials and studies. The literature search included a review of primary sources (e.g., journal articles) that reported study data results and key secondary sources such as meta-reviews available through PubMed, as well as reviews of clinical trial descriptions and results as reported in clinicaltrials.gov, conference publications and news releases. EXPERT OPINION LCA-RPE65 gene therapy is an example of successful, innovative, translational research. Further research is needed regarding how retinal gene therapy can be improved.
Collapse
Affiliation(s)
- Linda Stein
- University of Massachusetts Medical School, UMass Memorial Eye Center, Department of Ophthalmology, 281 Lincoln St., Worcester, MA 01605, USA
| | | | | | | |
Collapse
|
50
|
Orban T, Palczewska G, Palczewski K. Retinyl ester storage particles (retinosomes) from the retinal pigmented epithelium resemble lipid droplets in other tissues. J Biol Chem 2011; 286:17248-58. [PMID: 21454509 DOI: 10.1074/jbc.m110.195198] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Levels of many hydrophobic cellular substances are tightly regulated because of their potential cytotoxicity. These compounds tend to self-aggregate in cytoplasmic storage depots termed lipid droplets/bodies that have well defined structures that contain additional components, including cholesterol and various proteins. Hydrophobic substances in these structures become mobilized in a specific and regulated manner as dictated by cellular requirements. Retinal pigmented epithelial cells in the eye produce retinyl ester-containing lipid droplets named retinosomes. These esters are mobilized to replenish the visual chromophore, 11-cis-retinal, and their storage ensures proper visual function despite fluctuations in dietary vitamin A intake. But it remains unclear whether retinosomes are structures specific to the eye or similar to lipid droplets in other organs/tissues that contain substances other than retinyl esters. Thus, we initially investigated the production of these lipid droplets in experimental cell lines expressing lecithin:retinol acyltransferase, a key enzyme involved in formation of retinyl ester-containing retinosomes from all-trans-retinol. We found that retinosomes and oleate-derived lipid droplets form and co-localize concomitantly, indicating their intrinsic structural similarities. Next, we isolated native retinosomes from bovine retinal pigmented epithelium and found that their protein and hydrophobic small molecular constituents were similar to those of lipid droplets reported for other experimental cell lines and tissues. These unexpected findings suggest a common mechanism for lipid droplet formation that exhibits broad chemical specificity for the hydrophobic substances being stored.
Collapse
Affiliation(s)
- Tivadar Orban
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | | | | |
Collapse
|