1
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Wang X, Yu H, Gao R, Liu M, Xie W. A comprehensive review of the family of very-long-chain fatty acid elongases: structure, function, and implications in physiology and pathology. Eur J Med Res 2023; 28:532. [PMID: 37981715 PMCID: PMC10659008 DOI: 10.1186/s40001-023-01523-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 11/10/2023] [Indexed: 11/21/2023] Open
Abstract
BACKGROUND The very-long-chain fatty acid elongase (ELOVL) family plays essential roles in lipid metabolism and cellular functions. This comprehensive review explores the structural characteristics, functional properties, and physiological significance of individual ELOVL isoforms, providing insights into lipid biosynthesis, cell membrane dynamics, and signaling pathways. AIM OF REVIEW This review aims to highlight the significance of the ELOVL family in normal physiology and disease development. By synthesizing current knowledge, we underscore the relevance of ELOVLs as potential therapeutic targets. KEY SCIENTIFIC CONCEPTS OF REVIEW We emphasize the association between dysregulated ELOVL expression and diseases, including metabolic disorders, skin diseases, neurodegenerative conditions, and cancer. The intricate involvement of ELOVLs in cancer biology, from tumor initiation to metastasis, highlights their potential as targets for anticancer therapies. Additionally, we discuss the prospects of using isoform-specific inhibitors and activators for metabolic disorders and cancer treatment. The identification of ELOVL-based biomarkers may advance diagnostics and personalized medicine. CONCLUSION The ELOVL family's multifaceted roles in lipid metabolism and cellular physiology underscore its importance in health and disease. Understanding their functions offers potential therapeutic avenues and personalized treatments.
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Affiliation(s)
- Xiangyu Wang
- Department of Gynecological Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, Shandong, 250117, People's Republic of China
| | - Hao Yu
- Department of Gynecological Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, Shandong, 250117, People's Republic of China
| | - Rong Gao
- Department of Gynecological Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, Shandong, 250117, People's Republic of China
| | - Ming Liu
- Department of Gynecological Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, Shandong, 250117, People's Republic of China
| | - Wenli Xie
- Department of Gynecology, The Second Hospital of Shandong University, Jinan, Shandong, 250033, People's Republic of China.
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2
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Nwagbo U, Bernstein PS. Understanding the Roles of Very-Long-Chain Polyunsaturated Fatty Acids (VLC-PUFAs) in Eye Health. Nutrients 2023; 15:3096. [PMID: 37513514 PMCID: PMC10383069 DOI: 10.3390/nu15143096] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 07/06/2023] [Accepted: 07/08/2023] [Indexed: 07/30/2023] Open
Abstract
Lipids serve many roles in the neural system, from synaptic stabilization and signaling to DNA regulation and neuroprotection. They also regulate inflammatory responses, maintain cellular membrane structure, and regulate the homeostatic balance of ions and signaling molecules. An imbalance of lipid subgroups is implicated in the progression of many retinal diseases, such as age-related macular degeneration (AMD), retinitis pigmentosa, and diabetic retinopathy, and diet can play a key role in influencing these diseases' onset, progression, and severity. A special class of lipids termed very-long-chain polyunsaturated fatty acids (VLC-PUFAs) is found exclusively in mammalian vertebrate retinas and a few other tissues. They comprise <2% of fatty acids in the retina and are depleted in the retinas of patients with diseases like diabetic retinopathy and AMD. However, the implications of the reduction in VLC-PUFA levels are poorly understood. Dietary supplementation studies and ELOVL4 transgene studies have had positive outcomes. However, much remains to be understood about their role in retinal health and the potential for targeted therapies against retinal disease.
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Affiliation(s)
- Uzoamaka Nwagbo
- Department of Pharmacology & Toxicology, University of Utah, Salt Lake City, UT 84132, USA;
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Paul S. Bernstein
- Department of Pharmacology & Toxicology, University of Utah, Salt Lake City, UT 84132, USA;
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
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3
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Swinkels D, Baes M. The essential role of docosahexaenoic acid and its derivatives for retinal integrity. Pharmacol Ther 2023; 247:108440. [PMID: 37201739 DOI: 10.1016/j.pharmthera.2023.108440] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 05/08/2023] [Accepted: 05/15/2023] [Indexed: 05/20/2023]
Abstract
The fatty acid composition of photoreceptor outer segment (POS) phospholipids diverges from other membranes, being highly enriched in polyunsaturated fatty acids (PUFAs). The most abundant PUFA is docosahexaenoic acid (DHA, C22:6n-3), an omega-3 PUFA that amounts to over 50% of the POS phospholipid fatty acid side chains. Interestingly, DHA is the precursor of other bioactive lipids such as elongated PUFAs and oxygenated derivatives. In this review, we present the current view on metabolism, trafficking and function of DHA and very long chain polyunsaturated fatty acids (VLC-PUFAs) in the retina. New insights on pathological features generated from PUFA deficient mouse models with enzyme or transporter defects and corresponding patients are discussed. Not only the neural retina, but also abnormalities in the retinal pigment epithelium are considered. Furthermore, the potential involvement of PUFAs in more common retinal degeneration diseases such as diabetic retinopathy, retinitis pigmentosa and age-related macular degeneration are evaluated. Supplementation treatment strategies and their outcome are summarized.
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Affiliation(s)
- Daniëlle Swinkels
- Laboratory of Cell Metabolism, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, 3000 Leuven, Belgium
| | - Myriam Baes
- Laboratory of Cell Metabolism, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, 3000 Leuven, Belgium.
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4
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Polyunsaturated Lipids in the Light-Exposed and Prooxidant Retinal Environment. Antioxidants (Basel) 2023; 12:antiox12030617. [PMID: 36978865 PMCID: PMC10044808 DOI: 10.3390/antiox12030617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/26/2023] [Accepted: 02/28/2023] [Indexed: 03/06/2023] Open
Abstract
The retina is an oxidative stress-prone tissue due to high content of polyunsaturated lipids, exposure to visible light stimuli in the 400–480 nm range, and high oxygen availability provided by choroidal capillaries to support oxidative metabolism. Indeed, lipids’ peroxidation and their conversion into reactive species promoting inflammation have been reported and connected to retinal degenerations. Here, we review recent evidence showing how retinal polyunsaturated lipids, in addition to oxidative stress and damage, may counteract the inflammatory response triggered by blue light-activated carotenoid derivatives, enabling long-term retina operation despite its prooxidant environment. These two aspects of retinal polyunsaturated lipids require tight control over their synthesis to avoid overcoming their protective actions by an increase in lipid peroxidation due to oxidative stress. We review emerging evidence on different transcriptional control mechanisms operating in retinal cells to modulate polyunsaturated lipid synthesis over the life span, from the immature to the ageing retina. Finally, we discuss the antioxidant role of food nutrients such as xanthophylls and carotenoids that have been shown to empower retinal cells’ antioxidant responses and counteract the adverse impact of prooxidant stimuli on sight.
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5
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Gorusupudi A, Nwagbo U, Bernstein PS. Role of VLC-PUFAs in Retinal and Macular Degeneration. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1415:257-261. [PMID: 37440042 DOI: 10.1007/978-3-031-27681-1_37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
Very-long-chain polyunsaturated fatty acids (VLC-PUFAs) are a special class of fatty acids that are present in the retina and a few other human tissues. They cannot be synthesized de novo and are rarely present in dietary sources. Structurally, these lipids are composed of a proximal end with a typical saturated fatty acid character and a distal end more characteristic of common PUFAs. They have not been studied in detail until recently due to their low abundance in these tissues and technical difficulties in assaying these lipids by conventional chromatography. This unique class of lipids has chain lengths greater than 24 carbons, with the longest typically 38 carbons long. There is increasing interest in understanding their roles in the maintenance of retinal membrane integrity and the prevention of macular degeneration and inherited retinal diseases.
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Affiliation(s)
- Aruna Gorusupudi
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Uzoamaka Nwagbo
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Paul S Bernstein
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, USA.
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6
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Kawaguchi K, Nagao H, Shindou H, Noguchi H. Conformations of Three Types of Ultra-Long-Chain Fatty Acids in Multicomponent Lipid Bilayers. J Phys Chem B 2022; 126:9316-9324. [PMID: 36334092 DOI: 10.1021/acs.jpcb.2c06189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Ultra-long-chain fatty acids (ULCFAs) are biosynthesized in certain types of tissues, but their biological roles remain unknown. Here, we report how the conformation of ULCFAs depends on the length and unsaturated-bond ratio of the ultra-long chains and the composition of the host bilayer membrane using molecular dynamics simulations. The ultra-long chain of ULCFAs flips between the two leaflets and fluctuates among three conformations: elongated, L-shaped, and turned. Furthermore, we found that the saturated ultra-long chain exhibited an elongated conformation more frequently than the unsaturated chain. In addition, the truncation of the ultra-long chain at C26 had little effect on the remaining ULCFAs. ULCFAs respond to lipid-density differences in the two leaflets, and the ratio of the elongated and turned conformations changed to reduce this difference. However, in cholesterol-containing membranes, ULCFAs exhibit no density difference after the flip-flop of cholesterol removes the difference.
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Affiliation(s)
- Kazutomo Kawaguchi
- Institute of Science and Engineering, Kanazawa University, Kanazawa920-1192, Ishikawa, Japan
| | - Hidemi Nagao
- Institute of Science and Engineering, Kanazawa University, Kanazawa920-1192, Ishikawa, Japan
| | - Hideo Shindou
- Department of Lipid Life Science, National Center for Global Health and Medicine, Shinjuku-ku, Tokyo162-8655, Japan.,Department of Medical Lipid Science, Graduate School of Medicine, University of Tokyo, Bunkyo-ku, Tokyo113-0033, Japan
| | - Hiroshi Noguchi
- Institute for Solid State Physics, University of Tokyo, Kashiwa277-8581, Chiba, Japan
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7
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Serrano R, Navarro JC, Sales C, Portolés T, Monroig Ó, Beltran J, Hernández F. Determination of very long-chain polyunsaturated fatty acids from 24 to 44 carbons in eye, brain and gonads of wild and cultured gilthead sea bream (Sparus aurata). Sci Rep 2022; 12:10112. [PMID: 35710933 PMCID: PMC9203556 DOI: 10.1038/s41598-022-14361-0] [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: 02/24/2022] [Accepted: 06/06/2022] [Indexed: 11/30/2022] Open
Abstract
Very long-chain (> C24) polyunsaturated fatty acids (VLC-PUFA) play an important role in the development of nervous system, retinal function and reproductive processes in vertebrates. Their presence in very small amounts in specific lipid classes, the lack of reference standards and their late elution in chromatographic analyses render their identification and, most important, their quantification, still a challenge. Consequently, a sensitive and feasible analytical methodology is needed. In this work, we have studied the effect of chain length, as well as the number and position of unsaturations (or double bonds) on the response of GC-APCI-(Q)TOF MS, to establish an analytical method for VLC-PUFA quantification. The developed methodology allows the quantification of these compounds down to 2.5 × 10–3 pmol/mg lipid. The reduction of VLC-PUFA levels in lipid fractions of the organs from the herein sampled farmed fish suggesting a yet undetected effect on these compounds of high vegetable oil aquafeed formulations, that currently dominate the market.
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Affiliation(s)
- Roque Serrano
- Research Institute for Pesticides and Water (IUPA), University Jaume I, Av. Sos Baynat S/N, 12071, Castellón, Spain. .,Research Unit of Marine Ecotoxicology, UJI, Associated Unit to CSIC by IATS, Av. Sos Baynat S/N, 12071, Castellón, Spain.
| | - Juan C Navarro
- Research Unit of Marine Ecotoxicology, UJI, Associated Unit to CSIC by IATS, Av. Sos Baynat S/N, 12071, Castellón, Spain.,Institute of Aquaculture Torre de la Sal (IATS), CSIC, 12595, Ribera de Cabanes, S/NCastellón, Cabanes, Spain
| | - Carlos Sales
- Research Institute for Pesticides and Water (IUPA), University Jaume I, Av. Sos Baynat S/N, 12071, Castellón, Spain
| | - Tania Portolés
- Research Institute for Pesticides and Water (IUPA), University Jaume I, Av. Sos Baynat S/N, 12071, Castellón, Spain
| | - Óscar Monroig
- Research Unit of Marine Ecotoxicology, UJI, Associated Unit to CSIC by IATS, Av. Sos Baynat S/N, 12071, Castellón, Spain.,Institute of Aquaculture Torre de la Sal (IATS), CSIC, 12595, Ribera de Cabanes, S/NCastellón, Cabanes, Spain
| | - Joaquin Beltran
- Research Institute for Pesticides and Water (IUPA), University Jaume I, Av. Sos Baynat S/N, 12071, Castellón, Spain
| | - Félix Hernández
- Research Institute for Pesticides and Water (IUPA), University Jaume I, Av. Sos Baynat S/N, 12071, Castellón, Spain.,Research Unit of Marine Ecotoxicology, UJI, Associated Unit to CSIC by IATS, Av. Sos Baynat S/N, 12071, Castellón, Spain
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8
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Bernstein PS. Nourishing Better Vision: The ARVO 2021 Mildred Weisenfeld Award Lecture. Invest Ophthalmol Vis Sci 2022; 63:13. [PMID: 35285848 PMCID: PMC8934560 DOI: 10.1167/iovs.63.3.13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Affiliation(s)
- Paul S Bernstein
- Moran Eye Center, University of Utah, Salt Lake City, Utah, United States
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9
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Schneider N, Sundaresan Y, Gopalakrishnan P, Beryozkin A, Hanany M, Levanon EY, Banin E, Ben-Aroya S, Sharon D. Inherited retinal diseases: Linking genes, disease-causing variants, and relevant therapeutic modalities. Prog Retin Eye Res 2021; 89:101029. [PMID: 34839010 DOI: 10.1016/j.preteyeres.2021.101029] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 11/11/2021] [Accepted: 11/16/2021] [Indexed: 12/11/2022]
Abstract
Inherited retinal diseases (IRDs) are a clinically complex and heterogenous group of visual impairment phenotypes caused by pathogenic variants in at least 277 nuclear and mitochondrial genes, affecting different retinal regions, and depleting the vision of affected individuals. Genes that cause IRDs when mutated are unique by possessing differing genotype-phenotype correlations, varying inheritance patterns, hypomorphic alleles, and modifier genes thus complicating genetic interpretation. Next-generation sequencing has greatly advanced the identification of novel IRD-related genes and pathogenic variants in the last decade. For this review, we performed an in-depth literature search which allowed for compilation of the Global Retinal Inherited Disease (GRID) dataset containing 4,798 discrete variants and 17,299 alleles published in 31 papers, showing a wide range of frequencies and complexities among the 194 genes reported in GRID, with 65% of pathogenic variants being unique to a single individual. A better understanding of IRD-related gene distribution, gene complexity, and variant types allow for improved genetic testing and therapies. Current genetic therapeutic methods are also quite diverse and rely on variant identification, and range from whole gene replacement to single nucleotide editing at the DNA or RNA levels. IRDs and their suitable therapies thus require a range of effective disease modelling in human cells, granting insight into disease mechanisms and testing of possible treatments. This review summarizes genetic and therapeutic modalities of IRDs, provides new analyses of IRD-related genes (GRID and complexity scores), and provides information to match genetic-based therapies such as gene-specific and variant-specific therapies to the appropriate individuals.
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Affiliation(s)
- Nina Schneider
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel
| | - Yogapriya Sundaresan
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel
| | - Prakadeeswari Gopalakrishnan
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel
| | - Avigail Beryozkin
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel
| | - Mor Hanany
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel
| | - Erez Y Levanon
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, 5290002, Israel
| | - Eyal Banin
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel
| | - Shay Ben-Aroya
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, 5290002, Israel
| | - Dror Sharon
- Department of Ophthalmology, Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Israel.
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10
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Urso C, Zhou H. Palmitic Acid Lipotoxicity in Microglia Cells Is Ameliorated by Unsaturated Fatty Acids. Int J Mol Sci 2021; 22:ijms22169093. [PMID: 34445796 PMCID: PMC8396597 DOI: 10.3390/ijms22169093] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 08/16/2021] [Accepted: 08/20/2021] [Indexed: 01/04/2023] Open
Abstract
Obesity and metabolic syndrome are associated with cognitive decline and dementia. Palmitic acid (PA) is increased in the cerebrospinal fluid of obese patients with cognitive impairment. This study was therefore designed to examine fatty acid (FA) lipotoxicity in BV2 microglia cells. We found that PA induced time- and dose-dependent decrease in cell viability and increase in cell death without affecting the cell cycle profile and that PA lipotoxicity did not depend on cell surface free fatty acid receptors but rather on FA uptake. Treatment with sulfosuccinimidyl oleate (SSO), an irreversible inhibitor of fatty acid translocase CD36, significantly inhibited FA uptake in BSA- and PA-treated cells and blocked PA-induced decrease in cell viability. Inhibition of ER stress or treatment with N-acetylcysteine was not able to rescue PA lipotoxicity. Our study also showed that unsaturated fatty acids (UFAs), such as linoleic acid (LA), oleic acid (OA), α-linolenic acid (ALA), and docosahexaenoic acid (DHA), were not lipotoxic but instead protected microglia against PA-induced decrease in cell viability. Co-treatment of PA with LA, OA, and DHA significantly inhibited FA uptake in PA-treated cells. All UFAs tested induced the incorporation of FAs into and the amount of neutral lipids, while PA did not significantly affect the amount of neutral lipids compared with BSA control.
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11
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Arunkumar R, Gorusupudi A, Li B, Blount JD, Nwagbo U, Kim HJ, Sparrow JR, Bernstein PS. Lutein and zeaxanthin reduce A2E and iso-A2E levels and improve visual performance in Abca4 -/-/Bco2 -/- double knockout mice. Exp Eye Res 2021; 209:108680. [PMID: 34161819 PMCID: PMC8595537 DOI: 10.1016/j.exer.2021.108680] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 06/08/2021] [Accepted: 06/17/2021] [Indexed: 10/21/2022]
Abstract
Accumulation of bisretinoids such as A2E and its isomer iso-A2E is thought to mediate blue light-induced oxidative damage associated with age-related macular degeneration (AMD) and autosomal recessive Stargardt disease (STGD1). We hypothesize that increasing dietary intake of the macular carotenoids lutein and zeaxanthin in individuals at risk of AMD and STGD1 can inhibit the formation of bisretinoids A2E and iso-A2E, which can potentially ameliorate macular degenerative diseases. To study the beneficial effect of macular carotenoids in a retinal degenerative diseases model, we used ATP-binding cassette, sub-family A member 4 (Abca4-/-)/β,β-carotene-9',10'-oxygenase 2 (Bco2-/-) double knockout (KO) mice that accumulate elevated levels of A2E and iso-A2E in the retinal pigment epithelium (RPE) and macular carotenoids in the retina. Abca4-/-/Bco2-/- and Abca4-/- mice were fed a lutein-supplemented chow, zeaxanthin-supplemented chow or placebo chow (~2.6 mg of carotenoid/mouse/day) for three months. Visual function and electroretinography (ERG) were measured after one month and three months of carotenoid supplementation. The lutein and zeaxanthin supplemented Abca4-/-/Bco2-/- mice had significantly lower levels of RPE/choroid A2E and iso-A2E compared to control mice fed with placebo chow and improved visual performance. Carotenoid supplementation in Abca4-/- mice minimally raised retinal carotenoid levels and did not show much difference in bisretinoid levels or visual function compared to the control diet group. There was a statistically significant inverse correlation between carotenoid levels in the retina and A2E and iso-A2E levels in the RPE/choroid. Supplementation with retinal carotenoids, especially zeaxanthin, effectively inhibits bisretinoid formation in a mouse model of STGD1 genetically enhanced to accumulate carotenoids in the retina. These results provide further impetus to pursue oral carotenoids as therapeutic interventions for STGD1 and AMD.
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Affiliation(s)
- Ranganathan Arunkumar
- Department of Ophthalmology and Visual Science, John A. Moran Eye Center, University of Utah, School of Medicine, Salt Lake City, UT, USA
| | - Aruna Gorusupudi
- Department of Ophthalmology and Visual Science, John A. Moran Eye Center, University of Utah, School of Medicine, Salt Lake City, UT, USA
| | - Binxing Li
- Department of Ophthalmology and Visual Science, John A. Moran Eye Center, University of Utah, School of Medicine, Salt Lake City, UT, USA
| | - J David Blount
- Department of Ophthalmology and Visual Science, John A. Moran Eye Center, University of Utah, School of Medicine, Salt Lake City, UT, USA
| | - Uzoamaka Nwagbo
- Department of Ophthalmology and Visual Science, John A. Moran Eye Center, University of Utah, School of Medicine, Salt Lake City, UT, USA
| | - Hye Jin Kim
- Department of Ophthalmology, Columbia University Medical Center, New York, NY, USA; Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, USA
| | - Janet R Sparrow
- Department of Ophthalmology, Columbia University Medical Center, New York, NY, USA; Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, USA
| | - Paul S Bernstein
- Department of Ophthalmology and Visual Science, John A. Moran Eye Center, University of Utah, School of Medicine, Salt Lake City, UT, USA.
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12
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Wade A, Rallabandi R, Lucas S, Oberg C, Gorusupudi A, Bernstein PS, Rainier JD. The synthesis of the very long chain polyunsaturated fatty acid (VLC-PUFA) 32:6 n-3. Org Biomol Chem 2021; 19:5563-5566. [PMID: 34080605 DOI: 10.1039/d1ob00491c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
This article describes the synthesis of VLC-PUFA 32:6 n-3, D2-labeled 32:6 n-3, and the uptake of 32:6 n-3 into mouse retinal tissue.
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Affiliation(s)
- Alexander Wade
- Department of Chemistry, University of Utah, 315 South, 1400 East, Salt Lake City, UT 84112, USA.
| | - Rameshu Rallabandi
- Department of Chemistry, University of Utah, 315 South, 1400 East, Salt Lake City, UT 84112, USA.
| | - Steven Lucas
- Department of Chemistry, University of Utah, 315 South, 1400 East, Salt Lake City, UT 84112, USA.
| | - Catrina Oberg
- Department of Chemistry, University of Utah, 315 South, 1400 East, Salt Lake City, UT 84112, USA.
| | - Aruna Gorusupudi
- Department of Ophthalmology and Visual Sciences, 65 Mario Capecchi Drive, Moran Eye Center, University of Utah, Salt Lake City, UT 84132, USA
| | - Paul S Bernstein
- Department of Ophthalmology and Visual Sciences, 65 Mario Capecchi Drive, Moran Eye Center, University of Utah, Salt Lake City, UT 84132, USA
| | - Jon D Rainier
- Department of Chemistry, University of Utah, 315 South, 1400 East, Salt Lake City, UT 84112, USA.
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13
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Retinal bioavailability and functional effects of a synthetic very-long-chain polyunsaturated fatty acid in mice. Proc Natl Acad Sci U S A 2021; 118:2017739118. [PMID: 33526677 DOI: 10.1073/pnas.2017739118] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Rare, nondietary very-long-chain polyunsaturated fatty acids (VLC-PUFAs) are uniquely found in the retina and a few other vertebrate tissues. These special fatty acids play a clinically significant role in retinal degeneration and development, but their physiological and interventional research has been hampered because pure VLC-PUFAs are scarce. We hypothesize that if Stargardt-3 or age-related macular degeneration patients were to consume an adequate amount of VLC-PUFAs that could be directly used in the retina, it may be possible to bypass the steps of lipid elongation mediated by the retina's ELOVL4 enzyme and to delay or prevent degeneration. We report the synthesis of a VLC-PUFA (32:6 n-3) in sufficient quantity to study its bioavailability and functional benefits in the mouse retina. We acutely and chronically gavage fed wild-type mice and Elovl4 rod-cone conditional knockout mice this synthetic VLC-PUFA to understand its bioavailability and its role in visual function. VLC-PUFA-fed wild-type and Elovl4 conditional knockout mice show a significant increase in retinal VLC-PUFA levels in comparison to controls. The VLC-PUFA-fed mice also had improvement in the animals' visual acuity and electroretinography measurements. Further studies with synthetic VLC-PUFAs will continue to expand our understanding of the physiological roles of these unique retinal lipids, particularly with respect to their potential utility for the treatment and prevention of retinal degenerative diseases.
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14
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Sethna S, Scott PA, Giese APJ, Duncan T, Jian X, Riazuddin S, Randazzo PA, Redmond TM, Bernstein SL, Riazuddin S, Ahmed ZM. CIB2 regulates mTORC1 signaling and is essential for autophagy and visual function. Nat Commun 2021; 12:3906. [PMID: 34162842 PMCID: PMC8222345 DOI: 10.1038/s41467-021-24056-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 05/26/2021] [Indexed: 02/06/2023] Open
Abstract
Age-related macular degeneration (AMD) is a multifactorial neurodegenerative disorder. Although molecular mechanisms remain elusive, deficits in autophagy have been associated with AMD. Here we show that deficiency of calcium and integrin binding protein 2 (CIB2) in mice, leads to age-related pathologies, including sub-retinal pigment epithelium (RPE) deposits, marked accumulation of drusen markers APOE, C3, Aβ, and esterified cholesterol, and impaired visual function, which can be rescued using exogenous retinoids. Cib2 mutant mice exhibit reduced lysosomal capacity and autophagic clearance, and increased mTORC1 signaling-a negative regulator of autophagy. We observe concordant molecular deficits in dry-AMD RPE/choroid post-mortem human tissues. Mechanistically, CIB2 negatively regulates mTORC1 by preferentially binding to 'nucleotide empty' or inactive GDP-loaded Rheb. Upregulated mTORC1 signaling has been implicated in lymphangioleiomyomatosis (LAM) cancer. Over-expressing CIB2 in LAM patient-derived fibroblasts downregulates hyperactive mTORC1 signaling. Thus, our findings have significant implications for treatment of AMD and other mTORC1 hyperactivity-associated disorders.
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Affiliation(s)
- Saumil Sethna
- Department of Otorhinolaryngology - Head & Neck Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Patrick A Scott
- Department of Ophthalmology & Visual Sciences, University of Louisville, Louisville, KY, USA
| | - Arnaud P J Giese
- Department of Otorhinolaryngology - Head & Neck Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Todd Duncan
- Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Xiaoying Jian
- Laboratory of Cellular and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Sheikh Riazuddin
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan
| | - Paul A Randazzo
- Laboratory of Cellular and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - T Michael Redmond
- Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Steven L Bernstein
- Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Saima Riazuddin
- Department of Otorhinolaryngology - Head & Neck Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Zubair M Ahmed
- Department of Otorhinolaryngology - Head & Neck Surgery, University of Maryland School of Medicine, Baltimore, MD, USA.
- Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, Baltimore, MD, USA.
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15
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Ruiz-Pastor MJ, Kutsyr O, Lax P, Cuenca N. Decrease in DHA and other fatty acids correlates with photoreceptor degeneration in retinitis pigmentosa. Exp Eye Res 2021; 209:108667. [PMID: 34119484 DOI: 10.1016/j.exer.2021.108667] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 05/21/2021] [Accepted: 06/07/2021] [Indexed: 10/21/2022]
Abstract
Fatty acids, and especially docosahexaenoic acid (DHA), are essential for photoreceptor cell integrity and are involved in the phototransduction cascade. In this study, we analyzed the changes in the fatty acid profile in the retina of the rd10 mouse, model of retinitis pigmentosa, in order to identify potential risk factors for retinal degeneration and possible therapeutic approaches. Fatty acids from C57BL/6J and rd10 mouse retinas were extracted with Folch's method and analyzed by gas chromatography/mass spectrometry. Changes in retinal morphology were evaluated by immunohistochemistry. The rd10 mouse retina showed a decreased number of photoreceptor rows and alterations in photoreceptor morphology compared to C57BL/6J mice. The total amount of fatty acids dropped by 29.4% in the dystrophic retinas compared to C57BL/6J retinas. A positive correlation was found between the retinal content of specific fatty acids and the number of photoreceptor rows. We found that the amount of several short-chain and long-chain saturated fatty acids, as well as monounsaturated fatty acids, decreased in the retina of rd10 mice. Moreover, the content of the n-6 polyunsaturated fatty acid arachidonic acid and the n-3 polyunsaturated DHA decreased markedly in the dystrophic retina. The fall of DHA was more pronounced, hence the n-6/n-3 ratio was significantly increased in the diseased retina. The content of specific fatty acids in the retina decreased with photoreceptor degeneration in retinitis pigmentosa mice, with a remarkable reduction in DHA and other saturated and unsaturated fatty acids. These fatty acids could be essential for photoreceptor cell viability, and they should be evaluated for the design of therapeutical strategies and nutritional supplements.
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Affiliation(s)
- María José Ruiz-Pastor
- Department of Physiology, Genetics, and Microbiology, University of Alicante, Alicante, Spain
| | - Oksana Kutsyr
- Department of Physiology, Genetics, and Microbiology, University of Alicante, Alicante, Spain
| | - Pedro Lax
- Department of Physiology, Genetics, and Microbiology, University of Alicante, Alicante, Spain.
| | - Nicolás Cuenca
- Department of Physiology, Genetics, and Microbiology, University of Alicante, Alicante, Spain.
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16
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Photoreceptor metabolic reprogramming: current understanding and therapeutic implications. Commun Biol 2021; 4:245. [PMID: 33627778 PMCID: PMC7904922 DOI: 10.1038/s42003-021-01765-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 01/28/2021] [Indexed: 02/06/2023] Open
Abstract
Acquired and inherited retinal disorders are responsible for vision loss in an increasing proportion of individuals worldwide. Photoreceptor (PR) death is central to the vision loss individuals experience in these various retinal diseases. Unfortunately, there is a lack of treatment options to prevent PR loss, so an urgent unmet need exists for therapies that improve PR survival and ultimately, vision. The retina is one of the most energy demanding tissues in the body, and this is driven in large part by the metabolic needs of PRs. Recent studies suggest that disruption of nutrient availability and regulation of cell metabolism may be a unifying mechanism in PR death. Understanding retinal cell metabolism and how it is altered in disease has been identified as a priority area of research. The focus of this review is on the recent advances in the understanding of PR metabolism and how it is critical to reduction-oxidation (redox) balance, the outer retinal metabolic ecosystem, and retinal disease. The importance of these metabolic processes is just beginning to be realized and unraveling the metabolic and redox pathways integral to PR health may identify novel targets for neuroprotective strategies that prevent blindness in the heterogenous group of retinal disorders.
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17
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Serrano R, Navarro JC, Portolés T, Sales C, Beltrán J, Monroig Ó, Hernández F. Identification of new, very long-chain polyunsaturated fatty acids in fish by gas chromatography coupled to quadrupole/time-of-flight mass spectrometry with atmospheric pressure chemical ionization. Anal Bioanal Chem 2020; 413:1039-1046. [PMID: 33210175 DOI: 10.1007/s00216-020-03062-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 11/02/2020] [Accepted: 11/11/2020] [Indexed: 10/23/2022]
Abstract
The characterization of very long-chain (>C24) polyunsaturated fatty acids (VLC-PUFAs), which are essential in the vision, neural function, and reproduction of vertebrates, is challenging because of the lack of reference standards and their very low concentrations in certain lipid classes. In this research, we have developed a new methodology for VLC-PUFA identification based on gas chromatography coupled to quadrupole/time-of-flight mass spectrometry with an atmospheric pressure chemical ionization source (GC-APCI-QTOF MS). The mass accuracy attainable with the innovative QTOF instrument, together with the soft ionization of the APCI source, provides valuable information on the intact molecule, traditionally lost with electron ionization sources due to the extensive fragmentation suffered. We have identified, for the first time, VLC-PUFAs with chains up to 44 carbons in eyes, brain, and gonads of gilthead sea bream, a commercially important fish in the Mediterranean. The added value of ion mobility-mass spectrometry (IMS), recently developed in combination with GC-QTOF MS, and the contribution of the collisional cross section (CCS) parameter in the characterization of novel VLC-PUFAs (for which reference standards are not available) have been also evaluated. The methodology developed has allowed assessing qualitative differences between farmed and wild fish, and opens new perspectives in a still scarcely known field of research.
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Affiliation(s)
- Roque Serrano
- Research Institute for Pesticides and Water (IUPA), University Jaume I, Av. Sos Baynat S/N, 12071, Castellón, Spain. .,Research Unit of Marine Ecotoxicology (IATS-IUPA), Ribera de Cabanes, S/N, 12595, Cabanes, Castellón, Spain.
| | - Juan Carlos Navarro
- Research Unit of Marine Ecotoxicology (IATS-IUPA), Ribera de Cabanes, S/N, 12595, Cabanes, Castellón, Spain.,Instituto de Acuicultura de Torre de la Sal (IATS-CSIC), Ribera de Cabanes, S/N, 12595, Cabanes, Castellón, Spain
| | - Tania Portolés
- Research Institute for Pesticides and Water (IUPA), University Jaume I, Av. Sos Baynat S/N, 12071, Castellón, Spain
| | - Carlos Sales
- Research Institute for Pesticides and Water (IUPA), University Jaume I, Av. Sos Baynat S/N, 12071, Castellón, Spain
| | - Joaquín Beltrán
- Research Institute for Pesticides and Water (IUPA), University Jaume I, Av. Sos Baynat S/N, 12071, Castellón, Spain
| | - Óscar Monroig
- Research Unit of Marine Ecotoxicology (IATS-IUPA), Ribera de Cabanes, S/N, 12595, Cabanes, Castellón, Spain.,Instituto de Acuicultura de Torre de la Sal (IATS-CSIC), Ribera de Cabanes, S/N, 12595, Cabanes, Castellón, Spain
| | - Félix Hernández
- Research Institute for Pesticides and Water (IUPA), University Jaume I, Av. Sos Baynat S/N, 12071, Castellón, Spain.,Research Unit of Marine Ecotoxicology (IATS-IUPA), Ribera de Cabanes, S/N, 12595, Cabanes, Castellón, Spain
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18
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Kawaguchi K, Nakagawa KM, Nakagawa S, Shindou H, Nagao H, Noguchi H. Conformation of ultra-long-chain fatty acid in lipid bilayer: Molecular dynamics study. J Chem Phys 2020; 153:165101. [PMID: 33138431 DOI: 10.1063/5.0026030] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Ultra-long-chain fatty acids (ULCFAs) are biosynthesized in the restricted tissues such as retina, testis, and skin. The conformation of a single ULCFA, in which the sn-1 unsaturated chain has 32 carbons, in three types of phospholipid bilayers is studied by molecular dynamics simulations. It is found that the ultra-long tail of the ULCFA flips between two leaflets and fluctuates among an elongation into the opposite leaflet, lies between two leaflets, and turns back. As the number ratio of lipids in the opposite leaflet increases, the ratio of the elongated shape linearly decreases in all three cases. Thus, ULCFAs can sense the density differences between the two leaflets and respond to these changes.
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Affiliation(s)
- Kazutomo Kawaguchi
- Institute of Science and Engineering, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Koh M Nakagawa
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Satoshi Nakagawa
- Institute of Science and Engineering, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Hideo Shindou
- Department of Lipid Signaling, National Center for Global Health and Medicine, Shinjuku-ku, Tokyo 162-8655, Japan
| | - Hidemi Nagao
- Institute of Science and Engineering, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Hiroshi Noguchi
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
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19
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Identification of Key Genes and Pathways Associated with Age-Related Macular Degeneration. J Ophthalmol 2020; 2020:2714746. [PMID: 32904543 PMCID: PMC7456487 DOI: 10.1155/2020/2714746] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 07/16/2020] [Accepted: 07/28/2020] [Indexed: 01/27/2023] Open
Abstract
Age-related macular degeneration (AMD) is the leading cause of severe, permanent vision loss among the elderly in the developed world. The cellular and molecular pathogenesis of initiation and development of AMD remain poorly delineated. The limited resources of the human AMD RPE/choroid tissues impeded the extensive study of the disease. To better understand the molecular and pathway changes in human AMD RPE/choroid tissues, we searched the literature and found three independent studies using high-throughput technology to analyze gene expression in 54 human AMD RPE/choroid tissues and 46 age-matched healthy controls. We downloaded these data, pooled them together, and reanalyzed the difference between molecular and pathways by the Ingenuity Pathway Analysis (IPA) database. Totally, 353 differentially expressed genes (DEGs) were identified, among which 181 genes were downregulated and 172 genes were upregulated in RPE/choroid of AMD patients. Furthermore, several significantly enriched biological processes, including cancer, organismal injury and abnormalities, and ophthalmic disease, were identified associated with these DEGs. By analysis of canonical pathway, the phototransduction pathway and atherosclerosis signaling were the top two significant canonical pathways altered in RPE/choroid tissues in human AMD. As expected, several ophthalmic disease-related molecules, including RHO, PDE6A, 3',5'-cyclic-GMP phosphodiesterase, and G protein alpha, were in the central nodes of disease network. The bioinformatics technology combined with the existing high-throughput data was applied to evaluate the underlying key genes and pathways in human AMD tissues, which may predict downstream and upstream biological processes and identify potential therapeutic intervention targets in human AMD.
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20
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Walchuk C, Suh M. Nutrition and the aging retina: A comprehensive review of the relationship between nutrients and their role in age-related macular degeneration and retina disease prevention. ADVANCES IN FOOD AND NUTRITION RESEARCH 2020; 93:293-332. [PMID: 32711865 DOI: 10.1016/bs.afnr.2020.04.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Age-related macular degeneration (AMD) is the leading cause of severe vision loss in developed countries and is highly common among aging individuals. Considering the rate at which the global population is aging, the increasing prevalence of AMD and age-related eye disease is cause for concern. AMD is associated with the degeneration of the macula, the most central region of the retina, leading to a loss of central vision. A wide array of research has focused on the ability of lipid soluble nutrients to prevent and mitigate the harmful effects of AMD. These nutrients in question tend to be highly saturated within retinal tissues including the carotenoids lutein and zeaxanthin and the polyunsaturated fatty acid docosahexaenoic acid (DHA). Additionally, the unique presence of very long chain polyunsaturated fatty acids (VLCPUFAs, C24-C36) in the retina may be essential to prevent retinal degeneration as demonstrated by abnormal retinal functioning in the absence of these novel fatty acids. Existing literature has suggested that lutein, zeaxanthin and DHA consumption tend to enhance the health of the retina, protecting against the development of AMD. However, little improvement to the previously deteriorated retina is demonstrated and more research is required to understand the role of these nutrients in the retina and for the prevention of AMD. Considering the global impact of AMD and age-related eye disease, utilizing nutrients to prevent the formation of these debilitating diseases is a highly affordable and promising strategy.
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Affiliation(s)
- Chelsey Walchuk
- Department of Food and Human Nutritional Sciences, University of Manitoba, Winnipeg, MB, Canada; Division of Neurodegenerative Disorders, Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada
| | - Miyoung Suh
- Department of Food and Human Nutritional Sciences, University of Manitoba, Winnipeg, MB, Canada; Division of Neurodegenerative Disorders, Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada.
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21
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Gorusupudi A, Chang FY, Nelson K, Hageman GS, Bernstein PS. n-3 PUFA Supplementation Alters Retinal Very-Long-Chain-PUFA Levels and Ratios in Diabetic Animal Models. Mol Nutr Food Res 2019; 63:e1801058. [PMID: 31106474 DOI: 10.1002/mnfr.201801058] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 04/16/2019] [Indexed: 12/26/2022]
Abstract
SCOPE Long-chain (LC)-PUFAs act as precursors for the special class of retinal lipids known as very-long-chain (VLC)-PUFAs and the effect of diabetes on retinal VLC-PUFA levels is unexplored. In order to understand the supplemental effect of omega-3 (n-3) LC-PUFAs on decreasing levels of VLC-PUFAs due to diabetes, Nile rats, which develop diabetes spontaneously, and Akita mouse, a genetic diabetes model, are chosen. METHODS AND RESULTS Human retinal punches from donors are collected from an eye bank; lipids are extracted and analyzed to study the alterations in VLC-PUFAs and their omega-3/omega-6 (n-3/n-6) ratios. Nile rats are fed a high-fat diet to induce hyperglycemia, and then an n-3 PUFA-rich diet is fed to the experimental group for 2 months. Diabetic male Akita mice and WT mice are fed with 5% fish-oil mixed in with their chow for 2 months to observe the effect of n-3 PUFAs. Results indicate that VLC-PUFA levels are lower in human diabetic and retinopathic retinal punches compared to age-matched controls. With supplementation of n-3 PUFAs, there is a significant increase in n-3/n-6 VLC-PUFA ratios in both animal models compared to diabetic controls. CONCLUSION Dietary supplementation with n-3 LC-PUFAs helps to prevent progression of diabetes and associated retinopathy.
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Affiliation(s)
- Aruna Gorusupudi
- Department of Opthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, 84132, UT, USA
| | - Fu-Yen Chang
- Department of Opthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, 84132, UT, USA
| | - Kelly Nelson
- Department of Opthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, 84132, UT, USA
| | - Gregory S Hageman
- Department of Opthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, 84132, UT, USA.,Sharon Eccles Steele Center for Translational Medicine
| | - Paul S Bernstein
- Department of Opthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, 84132, UT, USA.,Sharon Eccles Steele Center for Translational Medicine
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22
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Identification of very long-chain (>C24) fatty acid methyl esters using gas chromatography coupled to quadrupole/time-of-flight mass spectrometry with atmospheric pressure chemical ionization source. Anal Chim Acta 2019; 1051:103-109. [DOI: 10.1016/j.aca.2018.11.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 10/30/2018] [Accepted: 11/01/2018] [Indexed: 12/20/2022]
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23
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Hopiavuori BR, Anderson RE, Agbaga MP. ELOVL4: Very long-chain fatty acids serve an eclectic role in mammalian health and function. Prog Retin Eye Res 2018; 69:137-158. [PMID: 30982505 PMCID: PMC6688602 DOI: 10.1016/j.preteyeres.2018.10.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 10/17/2018] [Accepted: 10/22/2018] [Indexed: 11/30/2022]
Abstract
ELOngation of Very Long chain fatty acids-4 (ELOVL4) is an elongase responsible for the biosynthesis of very long chain (VLC, ≥C28) saturated (VLC-SFA) and polyunsaturated (VLC-PUFA) fatty acids in brain, retina, skin, Meibomian glands, and testes. Fascinatingly, different mutations in this gene have been reported to cause vastly different phenotypes in humans. Heterozygous inheritance of seven different mutations in the coding sequence and 5' untranslated region of ELOVL4 causes autosomal dominant Stargardt-like macular dystrophy (STGD3), while homozygous inheritance of three more mutant variants causes severe seizures with ichthyosis, hypertonia, and even death. Some recent studies have described heterozygous inheritance in yet another three mutant ELOVL4 variants, two that cause spinocerebellar ataxia-34 (SCA34) with erythrokeratodermia (EKV) and one that causes SCA34 without EKV. We identified the specific enzymatic reactions catalyzed by ELOVL4 and, using a variety of genetically engineered mouse models, have actively searched for the mechanisms by which ELOVL4 impacts neural function and health. In this review, we critically compare and contrast the various animal model and case studies involving ELOVL4 deficiency via either mutation or deletion, and the resulting consequences on neuronal health and function in both the retina and central nervous system.
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Affiliation(s)
- Blake R Hopiavuori
- Oklahoma Center for Neurosciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Robert E Anderson
- Oklahoma Center for Neurosciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Reynolds Oklahoma Center on Aging, Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
| | - Martin-Paul Agbaga
- Oklahoma Center for Neurosciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
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24
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Santiago Valtierra FX, Peñalva DA, Luquez JM, Furland NE, Vásquez C, Reyes JG, Aveldaño MI, Oresti GM. Elovl4 and Fa2h expression during rat spermatogenesis: a link to the very-long-chain PUFAs typical of germ cell sphingolipids. J Lipid Res 2018; 59:1175-1189. [PMID: 29724783 DOI: 10.1194/jlr.m081885] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Revised: 04/27/2018] [Indexed: 12/14/2022] Open
Abstract
The sphingolipids (SLs) of rodent spermatogenic cells (spermatocytes, spermatids) and spermatozoa contain nonhydroxylated and 2-hydroxylated versions of very-long-chain (C26-C32) PUFAs (n-V and h-V, respectively) not present in Sertoli cells (SCs). Here, we investigated the expression of selected fatty acid elongases [elongation of very-long-chain fatty acid protein (Elovl)], with a focus on Elovl4, and a fatty acid 2-hydroxylase (Fa2h) in rat testes with postnatal development and germ cell differentiation. Along with Elovl5 and Elovl2, Elovl4 was actively transcribed in the adult testis. Elovl4 mRNA levels were high in immature testes and SCs, though the protein was absent. The Elovl4 protein was a germ cell product. All cells under study elongated [3H]arachidonate to tetraenoic and pentaenoic C24 PUFA, but only germ cells produced C26-C32 PUFAs. Spermatocytes displayed the highest Elovl4 protein levels and enzymatic activity. Fa2h mRNA was produced exclusively in germ cells, mostly round spermatids. As a protein, Fa2h was mainly concentrated in late spermatids, in the step of spermiogenesis in which they elongate and their heads change shape. The expression of Elovl4 and Fa2h thus correlate with the abundance of n-Vs and h-Vs in the SLs of rat spermatocytes and spermatids, respectively.
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Affiliation(s)
- Florencia X Santiago Valtierra
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) y Universidad Nacional del Sur (UNS), Bahía Blanca, Argentina
| | - Daniel A Peñalva
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) y Universidad Nacional del Sur (UNS), Bahía Blanca, Argentina
| | - Jessica M Luquez
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) y Universidad Nacional del Sur (UNS), Bahía Blanca, Argentina
| | - Natalia E Furland
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) y Universidad Nacional del Sur (UNS), Bahía Blanca, Argentina
| | - Claudia Vásquez
- Instituto de Química, Facultad de Ciencias, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
| | - Juan G Reyes
- Instituto de Química, Facultad de Ciencias, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
| | - Marta I Aveldaño
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) y Universidad Nacional del Sur (UNS), Bahía Blanca, Argentina
| | - Gerardo M Oresti
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) y Universidad Nacional del Sur (UNS), Bahía Blanca, Argentina
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25
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Dejos C, Kuny S, Han WH, Capel H, Lemieux H, Sauvé Y. Photoreceptor-induced RPE phagolysosomal maturation defects in Stargardt-like Maculopathy (STGD3). Sci Rep 2018; 8:5944. [PMID: 29654292 PMCID: PMC5899129 DOI: 10.1038/s41598-018-24357-4] [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: 02/08/2018] [Accepted: 03/28/2018] [Indexed: 11/09/2022] Open
Abstract
For many neurodegenerative disorders, expression of a pathological protein by one cell type impedes function of other cell types, which in turn contributes to the death of the first cell type. In transgenic mice modelling Stargardt-like (STGD3) maculopathy, human mutant ELOVL4 expression by photoreceptors is associated with defects in the underlying retinal pigment epithelium (RPE). To examine how photoreceptors exert cytotoxic effects on RPE cells, transgenic ELOVL4 (TG1-2 line; TG) and wild-type (WT) littermates were studied one month prior (preclinical stage) to onset of photoreceptor loss (two months). TG photoreceptor outer segments presented to human RPE cells are recognized and internalized into phagosomes, but their digestion is delayed. Live RPE cell imaging pinpoints decreased numbers of acidified phagolysomes. In vivo, master regulator of lysosomal genes, transcription factor EB (TFEB), and key lysosomal enzyme Cathepsin D are both unaffected. Oxidative stress, as ruled out with high-resolution respirometry, does not play a role at such an early stage. Upregulation of CRYBA1/A3 and phagocytic cells (microglia/macrophages) interposed between RPE and photoreceptors support adaptive responses to processing delays. Impaired phagolysosomal maturation is observed in RPE of mice expressing human mutant ELOVL4 in their photoreceptors prior to photoreceptor death and associated vision loss.
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Affiliation(s)
- Camille Dejos
- Department of Ophthalmology and Visual Sciences, University of Alberta, 7-45 Medical Sciences Building, Edmonton, AB, T6G 2H7, Canada
| | - Sharee Kuny
- Department of Ophthalmology and Visual Sciences, University of Alberta, 7-45 Medical Sciences Building, Edmonton, AB, T6G 2H7, Canada
| | - Woo Hyun Han
- Department of Ophthalmology and Visual Sciences, University of Alberta, 7-45 Medical Sciences Building, Edmonton, AB, T6G 2H7, Canada
| | - Heather Capel
- Department of Physiology, University of Alberta, 7-45 Medical Sciences Building, Edmonton, AB, T6G 2H7, Canada
| | - Hélène Lemieux
- Faculty Saint-Jean, University of Alberta, 8406 Rue Marie-Anne Gaboury Northwest, Edmonton, AB, T6C 4G9, Canada
| | - Yves Sauvé
- Department of Ophthalmology and Visual Sciences, University of Alberta, 7-45 Medical Sciences Building, Edmonton, AB, T6G 2H7, Canada. .,Department of Physiology, University of Alberta, 7-45 Medical Sciences Building, Edmonton, AB, T6G 2H7, Canada.
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Rajagopal R, Zhang S, Wei X, Doggett T, Adak S, Enright J, Shah V, Ling G, Chen S, Yoshino J, Hsu FF, Semenkovich CF. Retinal de novo lipogenesis coordinates neurotrophic signaling to maintain vision. JCI Insight 2018; 3:97076. [PMID: 29321376 PMCID: PMC5821215 DOI: 10.1172/jci.insight.97076] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 11/28/2017] [Indexed: 11/17/2022] Open
Abstract
Membrane lipid composition is central to the highly specialized functions of neurological tissues. In the retina, abnormal lipid metabolism causes severe forms of blindness, often through poorly understood neuronal cell death. Here, we demonstrate that deleting the de novo lipogenic enzyme fatty acid synthase (FAS) from the neural retina, but not the vascular retina, results in progressive neurodegeneration and blindness with a temporal pattern resembling rodent models of retinitis pigmentosa. Blindness was not rescued by protection from light-evoked activity; by eating a diet enriched in palmitate, the product of the FAS reaction; or by treatment with the PPARα agonist fenofibrate. Vision loss was due to aberrant synaptic structure, blunted responsiveness to glial-derived neurotrophic factor and ciliary neurotrophic factor, and eventual apoptotic cell loss. This progressive neurodegeneration was associated with decreased membrane cholesterol content, as well as loss of discrete n-3 polyunsaturated fatty acid- and saturated fatty acid-containing phospholipid species within specialized membrane microdomains. Neurotrophic signaling was restored by exogenous cholesterol delivery. These findings implicate de novo lipogenesis in neurotrophin-dependent cell survival by maintaining retinal membrane configuration and lipid composition, and they suggest that ongoing lipogenesis may be required to prevent cell death in many forms of retinopathy.
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Affiliation(s)
| | - Sheng Zhang
- Department of Ophthalmology and Visual Sciences
| | - Xiaochao Wei
- Division of Endocrinology, Metabolism, and Lipid Research
| | | | - Sangeeta Adak
- Division of Endocrinology, Metabolism, and Lipid Research
| | | | - Vaishali Shah
- Division of Endocrinology, Metabolism, and Lipid Research
| | - Guoyu Ling
- Division of Endocrinology, Metabolism, and Lipid Research
| | | | - Jun Yoshino
- Division of Geriatrics and Nutritional Science, and
| | - Fong-Fu Hsu
- Division of Endocrinology, Metabolism, and Lipid Research
| | - Clay F Semenkovich
- Division of Endocrinology, Metabolism, and Lipid Research.,Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri, USA
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27
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Elovl4 5-bp deletion does not accelerate cone photoreceptor degeneration in an all-cone mouse. PLoS One 2018; 13:e0190514. [PMID: 29293603 PMCID: PMC5749830 DOI: 10.1371/journal.pone.0190514] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 12/15/2017] [Indexed: 02/04/2023] Open
Abstract
Mutations in the elongation of very long chain fatty acid 4 (ELOVL4) gene cause Stargardt macular dystrophy 3 (STGD3), a rare, juvenile-onset, autosomal dominant form of macular degeneration. Although several mouse models have already been generated to investigate the link between the three identified disease-causing mutations in the ELOVL4 gene, none of these models recapitulates the early-onset cone photoreceptor cell death observed in the macula of STGD3 patients. To address this specifically, we investigated the effect of mutant ELOVL4 in a mouse model with an all-cone retina. Hence, we bred mice carrying the heterozygously mutated Elovl4 gene on the R91W;Nrl-/- all-cone background and analyzed the retinal lipid composition, morphology, and function over the course of 1 year. We observed a reduction of total phosphatidylcholine-containing very long chain-polyunsaturated fatty acids (PC-VLC-PUFAs) by 39% in the R91W;Nrl-/-;Elovl4 mice already at 6 weeks of age with a pronounced decline of the longest forms of PC-VLC-PUFAs. Total levels of shorter-chain fatty acids (< C26) remained unaffected. However, this reduction in PC-VLC-PUFA content in the all-cone retina had no impact on morphology or function and did not accelerate retinal degeneration in the R91W;Nrl-/-;Elovl4 mice. Taken together, mutations in the ELOVL4 gene lead to cone degeneration in humans, whereas mouse models expressing the mutant Elovl4 show predominant rod degeneration. The lack of a phenotype in the all-cone retina expressing the mutant form of the protein supports the view that aberrant function of ELOVL4 is especially detrimental for rods in mice and suggests a more subtle role of VLC-PUFAs for cone maintenance and survival.
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28
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Yarishkin O, Phuong TTT, Lakk M, Križaj D. TRPV4 Does Not Regulate the Distal Retinal Light Response. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1074:553-560. [PMID: 29721987 DOI: 10.1007/978-3-319-75402-4_67] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The transient receptor potential vanilloid isoform 4 (TRPV4) functions as polymodal transducer of swelling, heat, stretch, and lipid metabolites, is widely expressed across sensory tissues, and has been implicated in pressure sensing in vertebrate retinas. Although TRPV4 knockout mice exhibit a variety of mechanosensory, nociceptive, and thermo- and osmoregulatory phenotypes, it is not known whether the transmission of light-induced signals in the eye is affected by the loss of TRPV4. We utilized field potentials, a measure of rod and cone signaling, to determine whether TRPV4 impacts on the generation and/or transmission of the photoreceptor light response and neurotransmission. Luminance intensity-response relationships were acquired in anesthetized wild-type and TRPV4-/- mice and evaluated for peak amplitude and implicit time under scotopic and photopic conditions. We found that the morphology of the outer retina is unaffected by the ablation of the Trpv4 gene. Calcium imaging of dissociated Müller glia showed that selective TRPV4 stimulation induces oscillatory calcium signals in adjacent rods. However, no differences in scotopic or photopic light-evoked signaling in the distal retina were observed in TRPV4-/- eyes, suggesting that TRPV4 signaling in healthy Müller cells does not modulate the transmission of light-evoked signals at rod and cone synapses.
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Affiliation(s)
- Oleg Yarishkin
- Department of Ophthalmology & Visual Sciences, Moran Eye Institute, Salt Lake City, UT, USA
| | - Tam T T Phuong
- Department of Ophthalmology & Visual Sciences, Moran Eye Institute, Salt Lake City, UT, USA
| | - Monika Lakk
- Department of Ophthalmology & Visual Sciences, Moran Eye Institute, Salt Lake City, UT, USA
| | - David Križaj
- Department of Ophthalmology & Visual Sciences, Moran Eye Institute, Salt Lake City, UT, USA. .,Department of Bioengineering, University of Utah, Salt Lake City, UT, USA. .,Department of Neurobiology & Anatomy, University of Utah, Salt Lake City, UT, USA.
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29
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Gorusupudi A, Liu A, Hageman GS, Bernstein PS. Associations of human retinal very long-chain polyunsaturated fatty acids with dietary lipid biomarkers. J Lipid Res 2016; 57:499-508. [PMID: 26764040 DOI: 10.1194/jlr.p065540] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Indexed: 11/20/2022] Open
Abstract
The human retina is well-known to have unique lipid profiles enriched in long-chain polyunsaturated fatty acids (LC-PUFAs) and very long-chain polyunsaturated fatty acids (VLC-PUFAs) that appear to promote normal retinal structure and function, but the influence of diet on retinal lipid profiles in health and disease remains controversial. In this study, we examined two independent cohorts of donor eyes and related their retinal lipid profiles with systemic biomarkers of lipid intake. We found that serum and red blood cell lipids, and to a lesser extent orbital fat, are indeed excellent biomarkers of retinal lipid content and n-3/n-6 ratios in both the LC-PUFA and VLC-PUFA series. Eyes from age-related macular degeneration (AMD) donors have significantly decreased levels of VLC-PUFAs and low n-3/n-6 ratios. These results are consistent with the protective role of dietary n-3 LC-PUFAs against AMD and emphasize the importance of monitoring systemic biomarkers of lipid intake when undertaking clinical trials of lipid supplements for prevention and treatment of retinal disease.
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Affiliation(s)
- Aruna Gorusupudi
- John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132
| | - Aihua Liu
- John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132
| | - Gregory S Hageman
- John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132 Sharon Eccles Steele Center for Translational Medicine, University of Utah School of Medicine, Salt Lake City, UT 84132
| | - Paul S Bernstein
- John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132 Sharon Eccles Steele Center for Translational Medicine, University of Utah School of Medicine, Salt Lake City, UT 84132
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30
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Barabas P, Gorusupudi A, Bernstein PS, Krizaj D. Mouse Models of Stargardt 3 Dominant Macular Degeneration. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 854:137-43. [PMID: 26427404 DOI: 10.1007/978-3-319-17121-0_19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Stargardt type 3 macular degeneration is dependent on a dominant defect in a single gene, ELOVL4 (elongase of very long chain fatty acids 4). The encoded enzyme, ELOVL4, is required for the synthesis of very long chain polyunsaturated fatty acids (VLC-PUFAs), a rare class of > C24 lipids. In vitro expression studies suggest that mutated ELOVL4(STGD3) proteins fold improperly, resulting in ER stress and formation of cytosolic aggresomes of wild type and mutant ELOVL4. Although a number of mouse models have been developed to determine whether photoreceptor cell loss in STGD3 results from depletion of VLC-PUFAs, aggresome-dependent cell stress or a combination of these two factors, none of these models adequately recapitulates the disease phenotype in humans. Thus, the precise molecular mechanism by which ELOVL4 mutation causes photoreceptor degeneration in mice and in human patients remains to be characterized. This mini review compares and evaluates current STGD3 mouse models and determines what conclusions can be drawn from past work.
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Affiliation(s)
- Peter Barabas
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Institute, University of Utah School of Medicine, 84132, Salt Lake City, UT, USA.
| | - Aruna Gorusupudi
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Institute, University of Utah School of Medicine, 84132, Salt Lake City, UT, USA.
| | - Paul S Bernstein
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Institute, University of Utah School of Medicine, 84132, Salt Lake City, UT, USA.
| | - David Krizaj
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Institute, University of Utah School of Medicine, 84132, Salt Lake City, UT, USA.
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31
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Current Progress in Deciphering Importance of VLC-PUFA in the Retina. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 854:145-51. [DOI: 10.1007/978-3-319-17121-0_20] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
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32
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Psychophysical testing in rodent models of glaucomatous optic neuropathy. Exp Eye Res 2015; 141:154-63. [PMID: 26144667 DOI: 10.1016/j.exer.2015.06.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 06/08/2015] [Accepted: 06/29/2015] [Indexed: 12/14/2022]
Abstract
Processing of visual information begins in the retina, with photoreceptors converting light stimuli into neural signals. Ultimately, signals are transmitted to the brain through signaling networks formed by interneurons, namely bipolar, horizontal and amacrine cells providing input to retinal ganglion cells (RGCs), which form the optic nerve with their axons. As part of the chronic nature of glaucomatous optic neuropathy, the increasing and irreversible damage and ultimately loss of neurons, RGCs in particular, occurs following progressive damage to the optic nerve head (ONH), eventually resulting in visual impairment and visual field loss. There are two behavioral assays that are typically used to assess visual deficits in glaucoma rodent models, the visual water task and the optokinetic drum. The visual water task can assess an animal's ability to distinguish grating patterns that are associated with an escape from water. The optokinetic drum relies on the optomotor response, a reflex turning of the head and neck in the direction of the visual stimuli, which usually consists of rotating black and white gratings. This reflex is a physiological response critical for keeping the image stable on the retina. Driven initially by the neuronal input from direction-selective RGCs, this reflex is comprised of a number of critical sensory and motor elements. In the presence of repeatable and defined stimuli, this reflex is extremely well suited to analyze subtle changes in the circuitry and performance of retinal neurons. Increasing the cycles of these alternating gratings per degree, or gradually reducing the contrast of the visual stimuli, threshold levels can be determined at which the animal is no longer tracking the stimuli, and thereby visual function of the animal can be determined non-invasively. Integrating these assays into an array of outcome measures that determine multiple aspects of visual function is a central goal in vision research and can be realized, for example, by the combination of measuring optomotor reflex function with electroretinograms (ERGs) and optical coherence tomography (OCT) of the retina. These structure-function correlations in vivo are urgently needed to identify disease mechanisms as potential new targets for drug development. Such a combination of the experimental assessment of the optokinetic reflex (OKR) or optomotor response (OMR) with other measures of retinal structure and function is especially valuable for research on GON. The chronic progression of the disease is characterized by a gradual decrease in function accompanied by a concomitant increase in structural damage to the retina, therefore the assessment of subtle changes is key to determining the success of novel intervention strategies.
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33
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Rice DS, Calandria JM, Gordon WC, Jun B, Zhou Y, Gelfman CM, Li S, Jin M, Knott EJ, Chang B, Abuin A, Issa T, Potter D, Platt KA, Bazan NG. Adiponectin receptor 1 conserves docosahexaenoic acid and promotes photoreceptor cell survival. Nat Commun 2015; 6:6228. [PMID: 25736573 PMCID: PMC4351799 DOI: 10.1038/ncomms7228] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 01/07/2015] [Indexed: 12/29/2022] Open
Abstract
The identification of pathways necessary for photoreceptor and retinal pigment epithelium (RPE) function is critical to uncover therapies for blindness. Here we report the discovery of adiponectin receptor 1 (AdipoR1) as a regulator of these cells’ functions. Docosahexaenoic acid (DHA) is avidly retained in photoreceptors, while mechanisms controlling DHA uptake and retention are unknown. Thus, we demonstrate that AdipoR1 ablation results in DHA reduction. In situ hybridization reveals photoreceptor and RPE cell AdipoR1 expression, blunted in AdipoR1−/− mice. We also find decreased photoreceptor-specific phosphatidylcholine containing very long-chain polyunsaturated fatty acids and severely attenuated electroretinograms. These changes precede progressive photoreceptor degeneration in AdipoR1−/− mice. RPE-rich eyecup cultures from AdipoR1−/− reveal impaired DHA uptake. AdipoR1 overexpression in RPE cells enhances DHA uptake, whereas AdipoR1 silencing has the opposite effect. These results establish AdipoR1 as a regulatory switch of DHA uptake, retention, conservation and elongation in photoreceptors and RPE, thus preserving photoreceptor cell integrity. Docosahexaenoic acid is a major and important retinal fatty acid that is recruited and retained in the photoreceptor membrane via an unknown mechanism. Here, Rice et al. show that adiponectin receptor 1 is a key molecular switch for docosahexaenoic acid membrane homeostasis and photoreceptor cell function.
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Affiliation(s)
- Dennis S Rice
- Lexicon Pharmaceuticals, 8800 Technology Forest Place, The Woodlands, Texas 77381, USA
| | - Jorgelina M Calandria
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health Sciences Center, 2020 Gravier Street, New Orleans, Louisiana 70112, USA
| | - William C Gordon
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health Sciences Center, 2020 Gravier Street, New Orleans, Louisiana 70112, USA
| | - Bokkyoo Jun
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health Sciences Center, 2020 Gravier Street, New Orleans, Louisiana 70112, USA
| | - Yongdong Zhou
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health Sciences Center, 2020 Gravier Street, New Orleans, Louisiana 70112, USA
| | - Claire M Gelfman
- Lexicon Pharmaceuticals, 8800 Technology Forest Place, The Woodlands, Texas 77381, USA
| | - Songhua Li
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health Sciences Center, 2020 Gravier Street, New Orleans, Louisiana 70112, USA
| | - Minghao Jin
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health Sciences Center, 2020 Gravier Street, New Orleans, Louisiana 70112, USA
| | - Eric J Knott
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health Sciences Center, 2020 Gravier Street, New Orleans, Louisiana 70112, USA
| | - Bo Chang
- The Jackson Laboratory, 600 Main Street, Bar Harbor, Maine 04609, USA
| | - Alex Abuin
- Lexicon Pharmaceuticals, 8800 Technology Forest Place, The Woodlands, Texas 77381, USA
| | - Tawfik Issa
- Lexicon Pharmaceuticals, 8800 Technology Forest Place, The Woodlands, Texas 77381, USA
| | - David Potter
- Lexicon Pharmaceuticals, 8800 Technology Forest Place, The Woodlands, Texas 77381, USA
| | - Kenneth A Platt
- Lexicon Pharmaceuticals, 8800 Technology Forest Place, The Woodlands, Texas 77381, USA
| | - Nicolas G Bazan
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health Sciences Center, 2020 Gravier Street, New Orleans, Louisiana 70112, USA
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34
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STAT3 promotes survival of mutant photoreceptors in inherited photoreceptor degeneration models. Proc Natl Acad Sci U S A 2014; 111:E5716-23. [PMID: 25512545 DOI: 10.1073/pnas.1411248112] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Inherited photoreceptor degenerations (IPDs), a group of incurable progressive blinding diseases, are caused by mutations in more than 200 genes, but little is known about the molecular pathogenesis of photoreceptor (PR) death. Increased retinal expression of STAT3 has been observed in response to many retinal insults, including IPDs, but the role of this increase in PR death is unknown. Here, we show that the expression of Stat3 is increased in PRs of the Tg(RHO P347S) and Prph2(rds) (/+) mouse models of IPD and is activated by tyrosine phosphorylation. PR-specific deletion of Stat3 substantially accelerated PR degeneration in both mutant strains. In contrast, increased PR-specific expression of ROSA26 (R26) alleles encoding either WT STAT3 (Stat3(wt)) or the gain-of-function variant STAT3(C) (Stat3(C)) improved PR survival in both models. Moreover, PR signaling in Tg(RHO P347S) mice carrying either a R26-Stat3(wt) or R26-Stat3(C) allele demonstrated increased a-wave amplitude of the scotopic electroretinogram. Phosphorylation of STAT3 at tyrosine 705 was required for the prosurvival effect because an R26-Stat3(Y705F) allele was not protective. The prosurvival role of enhanced Stat3 activity was validated using recombinant adenoassociated virus (rAAV) vector-mediated PR Stat3 expression in Tg(RHO P347S) mice. Our findings (i) establish that the increase in endogenous PR Stat3 expression is a protective response in IPDs, (ii) suggest that therapeutic augmentation of PR Stat3 expression has potential as a common neuroprotective therapy for these disorders, and (iii) indicate that prosurvival molecules whose expression is increased in mutant PRs may have promise as novel therapies for IPDs.
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35
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Di Gregorio E, Borroni B, Giorgio E, Lacerenza D, Ferrero M, Lo Buono N, Ragusa N, Mancini C, Gaussen M, Calcia A, Mitro N, Hoxha E, Mura I, Coviello DA, Moon YA, Tesson C, Vaula G, Couarch P, Orsi L, Duregon E, Papotti MG, Deleuze JF, Imbert J, Costanzi C, Padovani A, Giunti P, Maillet-Vioud M, Durr A, Brice A, Tempia F, Funaro A, Boccone L, Caruso D, Stevanin G, Brusco A. ELOVL5 mutations cause spinocerebellar ataxia 38. Am J Hum Genet 2014; 95:209-17. [PMID: 25065913 DOI: 10.1016/j.ajhg.2014.07.001] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 07/02/2014] [Indexed: 12/18/2022] Open
Abstract
Spinocerebellar ataxias (SCAs) are a heterogeneous group of autosomal-dominant neurodegenerative disorders involving the cerebellum and 23 different genes. We mapped SCA38 to a 56 Mb region on chromosome 6p in a SCA-affected Italian family by whole-genome linkage analysis. Targeted resequencing identified a single missense mutation (c.689G>T [p.Gly230Val]) in ELOVL5. Mutation screening of 456 independent SCA-affected individuals identified the same mutation in two further unrelated Italian families. Haplotyping showed that at least two of the three families shared a common ancestor. One further missense variant (c.214C>G [p.Leu72Val]) was found in a French family. Both missense changes affect conserved amino acids, are predicted to be damaging by multiple bioinformatics tools, and were not identified in ethnically matched controls or within variant databases. ELOVL5 encodes an elongase involved in the synthesis of polyunsaturated fatty acids of the ω3 and ω6 series. Arachidonic acid and docosahexaenoic acid, two final products of the enzyme, were reduced in the serum of affected individuals. Immunohistochemistry on control mice and human brain demonstrated high levels in Purkinje cells. In transfection experiments, subcellular localization of altered ELOVL5 showed a perinuclear distribution with a signal increase in the Golgi compartment, whereas the wild-type showed a widespread signal in the endoplasmic reticulum. SCA38 and SCA34 are examples of SCAs due to mutations in elongase-encoding genes, emphasizing the importance of fatty-acid metabolism in neurological diseases.
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Affiliation(s)
- Eleonora Di Gregorio
- Department of Medical Sciences, University of Torino, 10126 Torino, Italy; Medical Genetics Unit, Azienda Ospedaliera Universitaria Città della Salute e della Scienza, 10126 Torino, Italy
| | - Barbara Borroni
- Department of Neurology, University of Brescia, 25100 Brescia, Italy
| | - Elisa Giorgio
- Department of Medical Sciences, University of Torino, 10126 Torino, Italy
| | - Daniela Lacerenza
- Department of Medical Sciences, University of Torino, 10126 Torino, Italy
| | - Marta Ferrero
- Department of Medical Sciences, University of Torino, 10126 Torino, Italy
| | - Nicola Lo Buono
- Department of Medical Sciences, University of Torino, 10126 Torino, Italy
| | - Neftj Ragusa
- Department of Medical Sciences, University of Torino, 10126 Torino, Italy
| | - Cecilia Mancini
- Department of Medical Sciences, University of Torino, 10126 Torino, Italy
| | - Marion Gaussen
- Institut National de la Santé et de la Recherche Médicale U1127, 75013 Paris, France; Centre National de la Recherche Scientifique UMR 7225, 75013 Paris, France; Sorbonne Universités, Université Pierre et Marie Curie (Paris 6) UMR_S 1127, Institut du Cerveau et de la Moelle Épinière, 75013 Paris, France; Neurogenetics team, École Pratique des Hautes Études, HéSam Université, 75013 Paris, France
| | - Alessandro Calcia
- Department of Medical Sciences, University of Torino, 10126 Torino, Italy
| | - Nico Mitro
- Department of Pharmacological and Biomolecular Sciences, University of Milano, 20133 Milano, Italy
| | - Eriola Hoxha
- Neuroscience Institute Cavalieri Ottolenghi, University of Torino, 10043 Orbassano, Italy
| | - Isabella Mura
- Laboratory of Human Genetics, Galliera Hospital, 16128 Genova, Italy
| | | | - Young-Ah Moon
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA
| | - Christelle Tesson
- Institut National de la Santé et de la Recherche Médicale U1127, 75013 Paris, France; Centre National de la Recherche Scientifique UMR 7225, 75013 Paris, France; Sorbonne Universités, Université Pierre et Marie Curie (Paris 6) UMR_S 1127, Institut du Cerveau et de la Moelle Épinière, 75013 Paris, France; Neurogenetics team, École Pratique des Hautes Études, HéSam Université, 75013 Paris, France
| | - Giovanna Vaula
- Neurologic Division 1, Department of Neuroscience and Mental Health, Azienda Ospedaliera Universitaria Città della Salute e della Scienza, 10126 Torino, Italy
| | - Philippe Couarch
- Institut National de la Santé et de la Recherche Médicale U1127, 75013 Paris, France; Centre National de la Recherche Scientifique UMR 7225, 75013 Paris, France; Sorbonne Universités, Université Pierre et Marie Curie (Paris 6) UMR_S 1127, Institut du Cerveau et de la Moelle Épinière, 75013 Paris, France
| | - Laura Orsi
- Neurologic Division 1, Department of Neuroscience and Mental Health, Azienda Ospedaliera Universitaria Città della Salute e della Scienza, 10126 Torino, Italy
| | - Eleonora Duregon
- Department of Oncology, University of Torino at San Luigi Hospital, 10043 Orbassano, Italy
| | - Mauro Giulio Papotti
- Department of Oncology, University of Torino at San Luigi Hospital, 10043 Orbassano, Italy
| | | | - Jean Imbert
- Transcriptomic and Genomic Marseille-Luminy platform, Technological Advances for Genomics and Clinics Laboratory, Institut National de la Santé et de la Recherche Médicale UMR_S 1090, Aix-Marseille University, 13009 Marseille, France
| | - Chiara Costanzi
- Department of Neurology, University of Brescia, 25100 Brescia, Italy
| | | | - Paola Giunti
- Department of Molecular Neuroscience, University College London Institute of Neurology, WC1 N3BG London, UK
| | | | - Alexandra Durr
- Institut National de la Santé et de la Recherche Médicale U1127, 75013 Paris, France; Centre National de la Recherche Scientifique UMR 7225, 75013 Paris, France; Sorbonne Universités, Université Pierre et Marie Curie (Paris 6) UMR_S 1127, Institut du Cerveau et de la Moelle Épinière, 75013 Paris, France; Fédération de Génétique, Pitié-Salpêtrière Hospital, Assistance Publique - Hôpitaux de Paris, 75013 Paris, France
| | - Alexis Brice
- Institut National de la Santé et de la Recherche Médicale U1127, 75013 Paris, France; Centre National de la Recherche Scientifique UMR 7225, 75013 Paris, France; Sorbonne Universités, Université Pierre et Marie Curie (Paris 6) UMR_S 1127, Institut du Cerveau et de la Moelle Épinière, 75013 Paris, France; Fédération de Génétique, Pitié-Salpêtrière Hospital, Assistance Publique - Hôpitaux de Paris, 75013 Paris, France
| | - Filippo Tempia
- Neuroscience Institute Cavalieri Ottolenghi, University of Torino, 10043 Orbassano, Italy
| | - Ada Funaro
- Department of Medical Sciences, University of Torino, 10126 Torino, Italy
| | - Loredana Boccone
- Ospedale Regionale Microcitemie, Azienda Unità Sanitaria Locale 8, 09121 Cagliari, Italy
| | - Donatella Caruso
- Neuroscience Institute Cavalieri Ottolenghi, University of Torino, 10043 Orbassano, Italy
| | - Giovanni Stevanin
- Institut National de la Santé et de la Recherche Médicale U1127, 75013 Paris, France; Centre National de la Recherche Scientifique UMR 7225, 75013 Paris, France; Sorbonne Universités, Université Pierre et Marie Curie (Paris 6) UMR_S 1127, Institut du Cerveau et de la Moelle Épinière, 75013 Paris, France; Neurogenetics team, École Pratique des Hautes Études, HéSam Université, 75013 Paris, France; Fédération de Génétique, Pitié-Salpêtrière Hospital, Assistance Publique - Hôpitaux de Paris, 75013 Paris, France
| | - Alfredo Brusco
- Department of Medical Sciences, University of Torino, 10126 Torino, Italy; Medical Genetics Unit, Azienda Ospedaliera Universitaria Città della Salute e della Scienza, 10126 Torino, Italy.
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Roosing S, Thiadens AAHJ, Hoyng CB, Klaver CCW, den Hollander AI, Cremers FPM. Causes and consequences of inherited cone disorders. Prog Retin Eye Res 2014; 42:1-26. [PMID: 24857951 DOI: 10.1016/j.preteyeres.2014.05.001] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 04/29/2014] [Accepted: 05/06/2014] [Indexed: 11/18/2022]
Abstract
Hereditary cone disorders (CDs) are characterized by defects of the cone photoreceptors or retinal pigment epithelium underlying the macula, and include achromatopsia (ACHM), cone dystrophy (COD), cone-rod dystrophy (CRD), color vision impairment, Stargardt disease (STGD) and other maculopathies. Forty-two genes have been implicated in non-syndromic inherited CDs. Mutations in the 5 genes implicated in ACHM explain ∼93% of the cases. On the contrary, only 21% of CRDs (17 genes) and 25% of CODs (8 genes) have been elucidated. The fact that the large majority of COD and CRD-associated genes are yet to be discovered hints towards the existence of unknown cone-specific or cone-sensitive processes. The ACHM-associated genes encode proteins that fulfill crucial roles in the cone phototransduction cascade, which is the most frequently compromised (10 genes) process in CDs. Another 7 CD-associated proteins are required for transport processes towards or through the connecting cilium. The remaining CD-associated proteins are involved in cell membrane morphogenesis and maintenance, synaptic transduction, and the retinoid cycle. Further novel genes are likely to be identified in the near future by combining large-scale DNA sequencing and transcriptomics technologies. For 31 of 42 CD-associated genes, mammalian models are available, 14 of which have successfully been used for gene augmentation studies. However, gene augmentation for CDs should ideally be developed in large mammalian models with cone-rich areas, which are currently available for only 11 CD genes. Future research will aim to elucidate the remaining causative genes, identify the molecular mechanisms of CD, and develop novel therapies aimed at preventing vision loss in individuals with CD in the future.
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Affiliation(s)
- Susanne Roosing
- Department of Human Genetics, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands; Radboud Institute for Molecular Life Sciences, Radboud University Nijmegen, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | | | - Carel B Hoyng
- Department of Ophthalmology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Caroline C W Klaver
- Department of Ophthalmology Erasmus Medical Centre, 3000 CA, Rotterdam, The Netherlands; Department of Epidemiology, Erasmus Medical Centre, 3000 CA, Rotterdam, The Netherlands
| | - Anneke I den Hollander
- Department of Human Genetics, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands; Radboud Institute for Molecular Life Sciences, Radboud University Nijmegen, PO Box 9101, 6500 HB, Nijmegen, The Netherlands; Department of Ophthalmology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Frans P M Cremers
- Department of Human Genetics, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands; Radboud Institute for Molecular Life Sciences, Radboud University Nijmegen, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
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Agbaga MP, Tam BM, Wong JS, Yang LL, Anderson RE, Moritz OL. Mutant ELOVL4 that causes autosomal dominant stargardt-3 macular dystrophy is misrouted to rod outer segment disks. Invest Ophthalmol Vis Sci 2014; 55:3669-80. [PMID: 24833735 DOI: 10.1167/iovs.13-13099] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Autosomal dominant Stargardt macular dystrophy caused by mutations in the Elongation of Very Long Chain fatty acids (ELOVL4) gene results in macular degeneration, leading to early childhood blindness. Transgenic mice and pigs expressing mutant ELOVL4 develop progressive photoreceptor degeneration. The mechanism by which these mutations cause macular degeneration remains unclear, but have been hypothesized to involve the loss of an ER-retention dilysine motif located in the extreme C-terminus. Dominant negative mechanisms and reduction in retinal polyunsaturated fatty acids also have been suggested. To understand the molecular mechanisms involved in disease progression in vivo, we addressed the hypothesis that the disease-linked C-terminal truncation mutant of ELOVL4 exerts a dominant negative effect on wild-type (WT) ELOVL4, altering its subcellular localization and function, which subsequently induces retinal degeneration and loss of vision. METHODS We generated transgenic Xenopus laevis that overexpress HA-tagged murine ELOVL4 variants in rod photoreceptors. RESULTS Tagged or untagged WT ELOVL4 localized primarily to inner segments. However, the mutant protein lacking the dilysine motif was mislocalized to post-Golgi compartments and outer segment disks. Coexpression of mutant and WT ELOVL4 in rods did not result in mislocalization of the WT protein to outer segments or in the formation of aggregates. Full-length HA-tagged ELOVL4 lacking the dilysine motif (K308R/K310R) necessary for targeting the WT ELOVL4 protein to the endoplasmic reticulum was similarly mislocalized to outer segments. CONCLUSIONS We propose that expression and outer segment mislocalization of the disease-linked 5-base-pair deletion mutant ELOVL4 protein alters photoreceptor structure and function, which subsequently results in retinal degeneration, and suggest three possible mechanisms by which mutant ELOVL4 may induce retinal degeneration in STGD3.
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Affiliation(s)
- Martin-Paul Agbaga
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States
| | - Beatrice M Tam
- Department of Ophthalmology and Vancouver Eye Care Center, University of British Columbia, Vancouver, Canada
| | - Jenny S Wong
- Department of Ophthalmology and Vancouver Eye Care Center, University of British Columbia, Vancouver, Canada
| | - Lee Ling Yang
- Department of Ophthalmology and Vancouver Eye Care Center, University of British Columbia, Vancouver, Canada
| | - Robert E Anderson
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Orson L Moritz
- Department of Ophthalmology and Vancouver Eye Care Center, University of British Columbia, Vancouver, Canada
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Mandal NA, Tran JTA, Zheng L, Wilkerson JL, Brush RS, McRae J, Agbaga MP, Zhang K, Petrukhin K, Ayyagari R, Anderson RE. In vivo effect of mutant ELOVL4 on the expression and function of wild-type ELOVL4. Invest Ophthalmol Vis Sci 2014; 55:2705-13. [PMID: 24644051 DOI: 10.1167/iovs.13-13198] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Mutations in the elongation of very long chain fatty acids 4 (ELOVL4) gene cause human Stargardt's macular dystrophy 3 (STGD3), a juvenile onset dominant form of macular degeneration. To understand the role of the ELOVL4 protein in retinal function, several mouse models have been developed by using transgenic (TG), knock-in (Elovl4(+/mut)), and knockout (Elovl4(+/-)) approaches. Here we analyzed quantitatively the ELOVL4 protein and its enzymatic products (very long chain saturated fatty acid [VLC-FA] and VLC-polyunsaturated fatty acid [VLC-PUFA]) in the retinas of 8 to 10-week-old TG1(+), TG2(+), and Elovl4(+/mut) mice that harbor the mutant ELOVL4 and compared them to their wild-type littermates and Elovl4(+/-) that do not express the mutant protein. We also analyzed skin from these mice to gain insight into the pathogenesis resulting from the ELOVL4 mutation. METHODS ELOVL4 protein localization in the retina was determined by immunohistochemistry. Levels of wild-type ELOVL4 protein in skin and retinas were determined by Western blotting. Total lipids from skin and retinas were measured by gas chromatography-mass spectrometry (GC-MS). Retinal glycerophosphatidylcholines (PC) were analyzed by tandem mass spectrometry. RESULTS Immunohistochemical and Western analysis indicated that wild-type ELOVL4 protein was reduced in heterozygous Elovl4(+/mut) and Elovl4(+/-) retinas, but not in TG2(+) retinas. We found that VLC-FA was reduced by 50% in the skin of Elovl4(+/-) and by 60% to 65% in Elovl4(+/mut). We found VLC-PUFA levels at ∼ 50% in both the retinas, and wild-type levels of VLC-PUFA in TG2(+) retinas. CONCLUSIONS We conclude that the presence of the mutant ELOVL4 does not affect the function of wild-type ELOVL4 in the fully developed 8- to 10-week-old retinas.
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Affiliation(s)
- Nawajes A Mandal
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
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Bennett LD, Hopiavuori BR, Brush RS, Chan M, Van Hook MJ, Thoreson WB, Anderson RE. Examination of VLC-PUFA-deficient photoreceptor terminals. Invest Ophthalmol Vis Sci 2014; 55:4063-72. [PMID: 24764063 DOI: 10.1167/iovs.14-13997] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Juvenile-onset autosomal dominant Stargardt-like macular dystrophy (STGD3) is caused by mutations in ELOVL4 (elongation of very long fatty acids-4), an elongase necessary for the biosynthesis of very long chain fatty acids (VLC-FAs ≥ C26). Photoreceptors are enriched with VLC polyunsaturated fatty acids (VLC-PUFAs), which are necessary for long-term survival of rod photoreceptors. The purpose of these studies was to determine the effect of deletion of VLC-PUFAs on rod synaptic function in retinas of mice conditionally depleted (KO) of Elovl4. METHODS Retina function was assessed in wild-type (WT) and KO by electroretinography. Outer plexiform structure was evaluated by immunofluorescence and transmission electron microscopy. Single-cell recordings measured rod ion channel operation and rod bipolar glutamate signaling. Sucrose gradient centrifugation was used to isolate synaptosomes from bovine retina. Proteins and lipids were analyzed by Western blotting and tandem mass spectroscopy, respectively. RESULTS Inner retinal responses (b-wave, oscillatory potentials, and scotopic threshold responses) of the ERG were decreased in the KO mice compared to controls. However the rod ion channel operation and bipolar glutamate responses were comparable between groups. Biochemical analysis revealed that conventional and ribbon synapses have VLC-PUFAs. Ultrastructural analysis showed that the outer plexiform layer was disorganized and the diameter of vesicles in rod terminals was smaller in the KO mice. CONCLUSIONS Very long chain PUFAs affect rod function by contributing to synaptic vesicle size, which may alter the dynamics of synaptic transmission, ultimately resulting in a loss of neuronal connectivity and death of rod photoreceptors.
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Affiliation(s)
- Lea D Bennett
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States
| | - Blake R Hopiavuori
- Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Richard S Brush
- Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Michael Chan
- Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Matthew J Van Hook
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, Nebraska, United States
| | - Wallace B Thoreson
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, Nebraska, United States Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, Nebraska, United States
| | - Robert E Anderson
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
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Bennett LD, Brush RS, Chan M, Lydic TA, Reese K, Reid GE, Busik JV, Elliott MH, Anderson RE. Effect of reduced retinal VLC-PUFA on rod and cone photoreceptors. Invest Ophthalmol Vis Sci 2014; 55:3150-7. [PMID: 24722693 DOI: 10.1167/iovs.14-13995] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Autosomal dominant Stargardt-like macular dystrophy (STGD3) is a juvenile-onset disease that is caused by mutations in Elovl4 (elongation of very long fatty acids-4). The Elovl4 catalyzes the first step in the conversion of C24 and longer fatty acids (FAs) to very long-chain FAs (VLC-FAs, ≥C26). Photoreceptors are particularly rich in VLC polyunsaturated FAs (VLC-PUFA). To explore the role of VLC-PUFAs in photoreceptors, we conditionally deleted Elovl4 in the mouse retina. METHODS Proteins were analyzed by Western blotting and lipids by gas chromatography (GC)-mass spectrometry, GC-flame ionization detection, and tandem mass spectrometry. Retina function was assessed by electroretinography (ERG), and structure was evaluated by bright field, immunofluorescence, and transmission electron microscopy. RESULTS Conditional deletion (KO) of retinal Elovl4 reduced RNA and protein levels by 91% and 96%, respectively. Total retina VLC-PUFAs were reduced by 88% compared to the wild type (WT) levels. Retinal VLC-PUFAs incorporated in phosphatidylcholine were less abundant at 12 months compared to 8-week-old levels. Amplitudes of the ERG a-wave were reduced by 22%, consistent with photoreceptor degeneration (11% loss of photoreceptors). Analysis of the rod a-wave responses gave no evidence of a role for VLC-PUFA in visual transduction. However, there were significant reductions in rod b-wave amplitudes (>30%) that could not be explained by loss of rod photoreceptors. There was no effect of VLC-PUFA reduction on cone ERG responses, and cone density was not different between the WT and KO mice at 12 months of age. CONCLUSIONS The VLC-PUFAs are important for rod, but not cone, function and for rod photoreceptor longevity.
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Affiliation(s)
- Lea D Bennett
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States
| | - Richard S Brush
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States
| | - Michael Chan
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States
| | - Todd A Lydic
- Department of Chemistry, Michigan State University, East Lansing, Michigan, United States
| | - Kristen Reese
- Department of Chemistry, Michigan State University, East Lansing, Michigan, United States
| | - Gavin E Reid
- Department of Chemistry, Michigan State University, East Lansing, Michigan, United States Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, United States
| | - Julia V Busik
- Department of Physiology, Michigan State University, East Lansing, Michigan, United States
| | - Michael H Elliott
- Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Robert E Anderson
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States Dean McGee Eye Institute, Oklahoma City, Oklahoma, United States Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
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Ichi I, Kono N, Arita Y, Haga S, Arisawa K, Yamano M, Nagase M, Fujiwara Y, Arai H. Identification of genes and pathways involved in the synthesis of Mead acid (20:3n-9), an indicator of essential fatty acid deficiency. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1841:204-13. [PMID: 24184513 DOI: 10.1016/j.bbalip.2013.10.013] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 10/10/2013] [Accepted: 10/24/2013] [Indexed: 12/18/2022]
Abstract
In mammals, 5,8,11-eicosatrienoic acid (Mead acid, 20:3n-9) is synthesized from oleic acid during a state of essential fatty acid deficiency (EFAD). Mead acid is thought to be produced by the same enzymes that synthesize arachidonic acid and eicosapentaenoic acid, but the genes and the pathways involved in the conversion of oleic acid to Mead acid have not been fully elucidated. The levels of polyunsaturated fatty acids in cultured cells are generally very low compared to those in mammalian tissues. In this study, we found that cultured cells, such as NIH3T3 and Hepa1-6 cells, have significant levels of Mead acid, indicating that cells in culture are in an EFAD state under normal culture conditions. We then examined the effect of siRNA-mediated knockdown of fatty acid desaturases and elongases on the level of Mead acid, and found that knockdown of Elovl5, Fads1, or Fads2 decreased the level of Mead acid. This and the measured levels of possible intermediate products for the synthesis of Mead acid such as 18:2n-9, 20:1n-9 and 20:2n-9 in the knocked down cells indicate two pathways for the synthesis of Mead acid: pathway 1) 18:1n-9→(Fads2)→18:2n-9→(Elovl5)→20:2n-9→(Fads1)→20:3n-9 and pathway 2) 18:1n-9→(Elovl5)→20:1n-9→(Fads2)→20:2n-9→(Fads1)→20:3n-9.
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Affiliation(s)
- Ikuyo Ichi
- Graduate School of Humanities and Sciences, Ochanomizu University, Tokyo 112-8610, Japan
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Comprehensive and sensitive quantification of long-chain and very long-chain polyunsaturated fatty acids in small samples of human and mouse retina. J Chromatogr A 2013; 1307:191-200. [DOI: 10.1016/j.chroma.2013.07.103] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 07/30/2013] [Accepted: 07/30/2013] [Indexed: 11/18/2022]
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Abstract
Photoreceptors are exquisitely adapted to transform light stimuli into electrical signals that modulate neurotransmitter release. These cells are organized into several compartments including the unique outer segment (OS). Its whole function is to absorb light and transduce this signal into a change of membrane potential. Another compartment is the inner segment where much of metabolism and regulation of membrane potential takes place and that connects the OS and synapse. The synapse is the compartment where changes in membrane potentials are relayed to other neurons in the retina via release of neurotransmitter. The composition of the plasma membrane surrounding these compartments varies to accommodate their specific functions. In this chapter, we discuss the organization of the plasma membrane emphasizing the protein composition of each region as it relates to visual signaling. We also point out examples where mutations in these proteins cause visual impairment.
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Affiliation(s)
- Sheila A Baker
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.
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