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Factors Differentiating the Antioxidant Activity of Macular Xanthophylls in the Human Eye Retina. Antioxidants (Basel) 2021; 10:antiox10040601. [PMID: 33919673 PMCID: PMC8070478 DOI: 10.3390/antiox10040601] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 04/01/2021] [Accepted: 04/07/2021] [Indexed: 02/06/2023] Open
Abstract
Macular xanthophylls, which are absorbed from the human diet, accumulate in high concentrations in the human retina, where they efficiently protect against oxidative stress that may lead to retinal damage. In addition, macular xanthophylls are uniquely spatially distributed in the retina. The zeaxanthin concentration (including the lutein metabolite meso-zeaxanthin) is ~9-fold greater than lutein concentration in the central fovea. These numbers do not correlate at all with the dietary intake of xanthophylls, for which there is a dietary zeaxanthin-to-lutein molar ratio of 1:12 to 1:5. The unique spatial distributions of macular xanthophylls—lutein, zeaxanthin, and meso-zeaxanthin—in the retina, which developed during evolution, maximize the protection of the retina provided by these xanthophylls. We will correlate the differences in the spatial distributions of macular xanthophylls with their different antioxidant activities in the retina. Can the major protective function of macular xanthophylls in the retina, namely antioxidant actions, explain their evolutionarily determined, unique spatial distributions? In this review, we will address this question.
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Zhorzholadze NV, Sheremet NL, Tanas AS, Strelnikov VV. [New possibilities in the treatment of Stargardt disease]. Vestn Oftalmol 2020; 136:333-343. [PMID: 32880159 DOI: 10.17116/oftalma2020136042333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Stargardt disease is a hereditary retinal dystrophy associated with mutations in the ABCA4 gene. Currently, no etiopathogenetic drugs nor treatment methods for Stargardt disease have completely passed clinical trials. The review summarizes experimental and clinical studies of drugs aimed at reducing the accumulation of vitamin A dimers, lipofuscin, complement inhibition and RPE regeneration by stem cell transplantation, as well as gene therapy studies with intravitreal vector injection of the ABCA4 functional gene.
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Affiliation(s)
| | - N L Sheremet
- Research Institute of Eye Diseases, Moscow, Russia
| | - A S Tanas
- Research Centre for Medical Genetics, Moscow, Russia
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Pamula F, Mühle J, Blanc A, Nehmé R, Edwards PC, Tate CG, Tsai CJ. Strategic Screening and Characterization of the Visual GPCR-mini-G Protein Signaling Complex for Successful Crystallization. J Vis Exp 2020. [PMID: 32225143 PMCID: PMC7250641 DOI: 10.3791/60747] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The key to determining crystal structures of membrane protein complexes is the quality of the sample prior to crystallization. In particular, the choice of detergent is critical, because it affects both the stability and monodispersity of the complex. We recently determined the crystal structure of an active state of bovine rhodopsin coupled to an engineered G protein, mini-Go, at 3.1 Å resolution. Here, we detail the procedure for optimizing the preparation of the rhodopsin–mini-Go complex. Dark-state rhodopsin was prepared in classical and neopentyl glycol (NPG) detergents, followed by complex formation with mini-Go under light exposure. The stability of the rhodopsin was assessed by ultraviolet-visible (UV-VIS) spectroscopy, which monitors the reconstitution into rhodopsin of the light-sensitive ligand, 9-cis retinal. Automated size-exclusion chromatography (SEC) was used to characterize the monodispersity of rhodopsin and the rhodopsin–mini-Go complex. SDS-polyacrylamide electrophoresis (SDS-PAGE) confirmed the formation of the complex by identifying a 1:1 molar ratio between rhodopsin and mini-Go after staining the gel with Coomassie blue. After cross-validating all this analytical data, we eliminated unsuitable detergents and continued with the best candidate detergent for large-scale preparation and crystallization. An additional problem arose from the heterogeneity of N-glycosylation. Heterologously-expressed rhodopsin was observed on SDS-PAGE to have two different N-glycosylated populations, which would probably have hindered crystallogenesis. Therefore, different deglycosylation enzymes were tested, and endoglycosidase F1 (EndoF1) produced rhodopsin with a single species of N-glycosylation. With this strategic pipeline for characterizing protein quality, preparation of the rhodopsin–mini-Go complex was optimized to deliver the crystal structure. This was only the third crystal structure of a GPCR–G protein signaling complex. This approach can also be generalized for other membrane proteins and their complexes to facilitate sample preparation and structure determination.
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Affiliation(s)
- Filip Pamula
- Laboratory of Biomolecular Research, Paul Scherrer Institute; Department of Biology, ETH Zürich;
| | - Jonas Mühle
- Laboratory of Biomolecular Research, Paul Scherrer Institute
| | - Alain Blanc
- Center for Radiopharmaceutical Sciences, Paul Scherrer Institute
| | - Rony Nehmé
- Laboratory of Molecular Biology, Medical Research Council
| | | | | | - Ching-Ju Tsai
- Laboratory of Biomolecular Research, Paul Scherrer Institute;
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Tao JX, Zhou WC, Zhu XG. Mitochondria as Potential Targets and Initiators of the Blue Light Hazard to the Retina. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2019; 2019:6435364. [PMID: 31531186 PMCID: PMC6721470 DOI: 10.1155/2019/6435364] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 06/18/2019] [Accepted: 07/25/2019] [Indexed: 12/20/2022]
Abstract
Commercially available white light-emitting diodes (LEDs) have an intense emission in the range of blue light, which has raised a range of public concerns about their potential risks as retinal hazards. Distinct from other visible light components, blue light is characterized by short wavelength, high energy, and strong penetration that can reach the retina with relatively little loss in damage potential. Mitochondria are abundant in retinal tissues, giving them relatively high access to blue light, and chromophores, which are enriched in the retina, have many mitochondria able to absorb blue light and induce photochemical effects. Therefore, excessive exposure of the retina to blue light tends to cause ROS accumulation and oxidative stress, which affect the structure and function of the retinal mitochondria and trigger mitochondria-involved death signaling pathways. In this review, we highlight the essential roles of mitochondria in blue light-induced photochemical damage and programmed cell death in the retina, indicate directions for future research and preventive targets in terms of the blue light hazard to the retina, and suggest applying LED devices in a rational way to prevent the blue light hazard.
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Affiliation(s)
- Jin-Xin Tao
- Department of Neurosurgery, The Second Affiliated Hospital of Nanchang University, Nanchang 330006, China
- Department of Clinical Medicine, The Second Clinical Medical College, Nanchang University, Nanchang 330006, China
| | - Wen-Chuan Zhou
- Department of Neurosurgery, The Second Affiliated Hospital of Nanchang University, Nanchang 330006, China
- Department of Clinical Medicine, The Second Clinical Medical College, Nanchang University, Nanchang 330006, China
| | - Xin-Gen Zhu
- Department of Neurosurgery, The Second Affiliated Hospital of Nanchang University, Nanchang 330006, China
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Kim KH, Lim DG, Lim JY, Kim NA, Park SH, Cho JH, Shin BS, Jeong SH. Chemical stability and in vitro and clinical efficacy of a novel hybrid retinoid derivative, bis-retinamido methylpentane. Int J Pharm 2015; 495:93-105. [PMID: 26325317 DOI: 10.1016/j.ijpharm.2015.08.081] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 08/05/2015] [Accepted: 08/26/2015] [Indexed: 10/23/2022]
Abstract
The anti-aging agent, retinol, has fewer side effects and similar biological activity compared to retinoic acid. However, retinol becomes unstable when exposed to light and heat. A novel hybrid retinoid derivative, bis-retinamido methylpentane (RS-2A), was newly developed to overcome the limitations. This study evaluated the chemical stability of RS-2A under thermal and light conditions by examining degradation profiles, and assessed the in vitro biological activity, cytotoxicity, and clinical efficacy. Chemical stability and degradation profiles were investigated with HPLC and LC-MS. Especially, photo-stability of RS-2A was analyzed under various conditions, such as change of physical state and concentration, different solvents, and various excipients. For analyses of cellular activity and cytotoxicity, human dermal fibroblasts were cultured with RS-2A. To evaluate the safety and efficacy of the compound with the cellular results, RS-2A was applied to women who had moderate to severe wrinkles at the periorbital region. All of the experiments were conducted with retinol as a reference. RS-2A was more stable than retinol to thermal conditions, especially in solution. Both RS-2A and retinol were unstable to light, but RS-2A showed enhanced photo-stability with regard to concentration, more polar solvent, and addition of proper excipients. RS-2A exhibited decreased cytotoxicity and enhanced effects on collagen synthesis compared with retinol. In a clinical study, a 4-week treatment with RS-2A significantly improved the appearance of periorbital wrinkles without any side effects. The results indicate that RS-2A might have potential as an anti-aging agent for cosmeceutical preparations because of its enhanced chemical stability, biological activity, safety, and clinical efficacy.
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Affiliation(s)
- Ki Hyun Kim
- College of Pharmacy, Dongguk University, Gyeonggi 410-820, Republic of Korea
| | - Dae Gon Lim
- College of Pharmacy, Dongguk University, Gyeonggi 410-820, Republic of Korea
| | - Jun Yeul Lim
- College of Pharmacy, Dongguk University, Gyeonggi 410-820, Republic of Korea
| | - Nam Ah Kim
- College of Pharmacy, Dongguk University, Gyeonggi 410-820, Republic of Korea
| | - So-Hyun Park
- Coway Cosmetics R&D Center, Seoul 153-803, Republic of Korea
| | - Jin Hun Cho
- Coway Cosmetics R&D Center, Seoul 153-803, Republic of Korea
| | - Beom Soo Shin
- College of Pharmacy, Catholic University of Daegu, Gyeongbuk, Republic of Korea
| | - Seong Hoon Jeong
- College of Pharmacy, Dongguk University, Gyeonggi 410-820, Republic of Korea.
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Bavik C, Henry SH, Zhang Y, Mitts K, McGinn T, Budzynski E, Pashko A, Lieu KL, Zhong S, Blumberg B, Kuksa V, Orme M, Scott I, Fawzi A, Kubota R. Visual Cycle Modulation as an Approach toward Preservation of Retinal Integrity. PLoS One 2015; 10:e0124940. [PMID: 25970164 PMCID: PMC4430241 DOI: 10.1371/journal.pone.0124940] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 03/19/2015] [Indexed: 01/10/2023] Open
Abstract
Increased exposure to blue or visible light, fluctuations in oxygen tension, and the excessive accumulation of toxic retinoid byproducts places a tremendous amount of stress on the retina. Reduction of visual chromophore biosynthesis may be an effective method to reduce the impact of these stressors and preserve retinal integrity. A class of non-retinoid, small molecule compounds that target key proteins of the visual cycle have been developed. The first candidate in this class of compounds, referred to as visual cycle modulators, is emixustat hydrochloride (emixustat). Here, we describe the effects of emixustat, an inhibitor of the visual cycle isomerase (RPE65), on visual cycle function and preservation of retinal integrity in animal models. Emixustat potently inhibited isomerase activity in vitro (IC50 = 4.4 nM) and was found to reduce the production of visual chromophore (11-cis retinal) in wild-type mice following a single oral dose (ED50 = 0.18 mg/kg). Measure of drug effect on the retina by electroretinography revealed a dose-dependent slowing of rod photoreceptor recovery (ED50 = 0.21 mg/kg) that was consistent with the pattern of visual chromophore reduction. In albino mice, emixustat was shown to be effective in preventing photoreceptor cell death caused by intense light exposure. Pre-treatment with a single dose of emixustat (0.3 mg/kg) provided a ~50% protective effect against light-induced photoreceptor cell loss, while higher doses (1–3 mg/kg) were nearly 100% effective. In Abca4-/- mice, an animal model of excessive lipofuscin and retinoid toxin (A2E) accumulation, chronic (3 month) emixustat treatment markedly reduced lipofuscin autofluorescence and reduced A2E levels by ~60% (ED50 = 0.47 mg/kg). Finally, in the retinopathy of prematurity rodent model, treatment with emixustat during the period of ischemia and reperfusion injury produced a ~30% reduction in retinal neovascularization (ED50 = 0.46mg/kg). These data demonstrate the ability of emixustat to modulate visual cycle activity and reduce pathology associated with various biochemical and environmental stressors in animal models. Other attributes of emixustat, such as oral bioavailability and target specificity make it an attractive candidate for clinical development in the treatment of retinal disease.
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Affiliation(s)
- Claes Bavik
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Susan Hayes Henry
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Yan Zhang
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Kyoko Mitts
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Tim McGinn
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Ewa Budzynski
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Andriy Pashko
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Kuo Lee Lieu
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Sheng Zhong
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Bruce Blumberg
- University of California, Irvine, School of Biological Sciences, 4351 Natural Sciences II, Irvine, California 92697, United States of America
| | - Vladimir Kuksa
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Mark Orme
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Ian Scott
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Ahmad Fawzi
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
| | - Ryo Kubota
- Acucela, Inc., 1301 2nd Avenue, Suite 1900, Seattle, Washington 98101, United States of America
- * E-mail:
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Demmig-Adams B, Adams RB. Eye nutrition in context: mechanisms, implementation, and future directions. Nutrients 2013; 5:2483-501. [PMID: 23857222 PMCID: PMC3738983 DOI: 10.3390/nu5072483] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Revised: 06/04/2013] [Accepted: 06/21/2013] [Indexed: 12/12/2022] Open
Abstract
Carotenoid-based visual cues and roles of carotenoids in human vision are reviewed, with an emphasis on protection by zeaxanthin and lutein against vision loss, and dietary sources of zeaxanthin and lutein are summarized. In addition, attention is given to synergistic interactions of zeaxanthin and lutein with other dietary factors affecting human vision (such as antioxidant vitamins, phenolics, and poly-unsaturated fatty acids) and the emerging mechanisms of these interactions. Emphasis is given to lipid oxidation products serving as messengers with functions in gene regulation. Lastly, the photo-physics of light collection and photoprotection in photosynthesis and vision are compared and their common principles identified as possible targets of future research.
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Affiliation(s)
- Barbara Demmig-Adams
- Department of Ecology & Evolutionary Biology, University of Colorado, Boulder, CO 80309-0334, USA.
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Abstract
The human eye is constantly exposed to sunlight and artificial lighting. Light transmission through the eye is fundamental to its unique biological functions of directing vision and circadian rhythm and therefore light absorbed by the eye must be benign. However, exposure to the very intense ambient radiation can pose a hazard particularly if the recipient is over 40 years of age. There are age-related changes in the endogenous (natural) chromophores (lipofuscin, A2E and all-trans-retinal derivatives) in the human retina that makes it more susceptible to visible light damage. Intense visible light sources that do not filter short blue visible light (400-440 nm) used for phototherapy of circadian imbalance (i.e. seasonal affective disorder) increase the risk for age-related light damage to the retina. Moreover, many drugs, dietary supplements, nanoparticles and diagnostic dyes (xenobiotics) absorb ocular light and have the potential to induce photodamage to the retina, leading to transient or permanent blinding disorders. This article will review the underlying reasons why visible light in general and short blue visible light in particular dramatically raises the risk of photodamage to the human retina.
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Affiliation(s)
- Albert R Wielgus
- Department of Ophthalmology, Duke University Medical Center, Durham, NC, USA
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Boon CJ, Klevering BJ, Leroy BP, Hoyng CB, Keunen JE, den Hollander AI. The spectrum of ocular phenotypes caused by mutations in the BEST1 gene. Prog Retin Eye Res 2009; 28:187-205. [DOI: 10.1016/j.preteyeres.2009.04.002] [Citation(s) in RCA: 181] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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