1
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Wang Y, Becker S, Finkelstein S, Dyka FM, Liu H, Eminhizer M, Hao Y, Brush RS, Spencer WJ, Arshavsky VY, Ash JD, Du J, Agbaga MP, Vinberg F, Ellis JM, Lobanova ES. Acyl-CoA synthetase 6 controls rod photoreceptor function and survival by shaping the phospholipid composition of retinal membranes. Commun Biol 2024; 7:1027. [PMID: 39169121 PMCID: PMC11339274 DOI: 10.1038/s42003-024-06691-8] [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: 11/14/2023] [Accepted: 08/06/2024] [Indexed: 08/23/2024] Open
Abstract
The retina is light-sensitive neuronal tissue in the back of the eye. The phospholipid composition of the retina is unique and highly enriched in polyunsaturated fatty acids, including docosahexaenoic fatty acid (DHA). While it is generally accepted that a high DHA content is important for vision, surprisingly little is known about the mechanisms of DHA enrichment in the retina. Furthermore, the biological processes controlled by DHA in the eye remain poorly defined as well. Here, we combined genetic manipulations with lipidomic analysis in mice to demonstrate that acyl-CoA synthetase 6 (Acsl6) serves as a regulator of the unique composition of retinal membranes. Inactivation of Acsl6 reduced the levels of DHA-containing phospholipids, led to progressive loss of light-sensitive rod photoreceptor neurons, attenuated the light responses of these cells, and evoked distinct transcriptional response in the retina involving the Srebf1/2 (sterol regulatory element binding transcription factors 1/2) pathway. This study identifies one of the major enzymes responsible for DHA enrichment in the retinal membranes and introduces a model allowing an evaluation of rod functioning and pathology caused by impaired DHA incorporation/retention in the retina.
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Affiliation(s)
- Yixiao Wang
- Department of Ophthalmology, University of Florida, Gainesville, FL, USA
| | - Silke Becker
- Department of Ophthalmology, University of Utah, Salt Lake City, UT, USA
| | | | - Frank M Dyka
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Haitao Liu
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Mark Eminhizer
- Departments of Ophthalmology and Visual Sciences and Biochemistry and Molecular Medicine, West Virginia University, Morgantown, WV, USA
| | - Ying Hao
- Department of Ophthalmology, Duke University, Durham, NC, USA
| | - Richard S Brush
- Department of Ophthalmology, University of Oklahoma Health Sciences Center and Dean McGee Eye Institute, Oklahoma City, OK, USA
| | - William J Spencer
- Department of Ophthalmology and Visual Sciences, SUNY Upstate Medical University, Syracuse, NY, USA
| | | | - John D Ash
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jianhai Du
- Departments of Ophthalmology and Visual Sciences and Biochemistry and Molecular Medicine, West Virginia University, Morgantown, WV, USA
| | - Martin-Paul Agbaga
- Department of Ophthalmology, University of Oklahoma Health Sciences Center and Dean McGee Eye Institute, Oklahoma City, OK, USA
| | - Frans Vinberg
- Department of Ophthalmology, University of Utah, Salt Lake City, UT, USA
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2
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Siddiqui AJ, Jahan S, Chaturvedi S, Siddiqui MA, Alshahrani MM, Abdelgadir A, Hamadou WS, Saxena J, Sundararaj BK, Snoussi M, Badraoui R, Adnan M. Therapeutic Role of ELOVL in Neurological Diseases. ACS OMEGA 2023; 8:9764-9774. [PMID: 36969404 PMCID: PMC10034982 DOI: 10.1021/acsomega.3c00056] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 02/23/2023] [Indexed: 06/18/2023]
Abstract
Fatty acids play an important role in controlling the energy balance of mammals. De novo lipogenesis also generates a significant amount of lipids that are endogenously produced in addition to their ingestion. Fatty acid elongation beyond 16 carbons (palmitic acid), which can lead to the production of very long chain fatty acids (VLCFA), can be caused by the rate-limiting condensation process. Seven elongases, ELOVL1-7, have been identified in mammals and each has a unique substrate specificity. Researchers have recently developed a keen interest in the elongation of very long chain fatty acids protein 1 (ELOVL1) enzyme as a potential treatment for a variety of diseases. A number of neurological disorders directly or indirectly related to ELOVL1 involve the elongation of monounsaturated (C20:1 and C22:1) and saturated (C18:0-C26:0) acyl-CoAs. VLCFAs and ELOVL1 have a direct impact on the neurological disease. Other neurological symptoms such as ichthyotic keratoderma, spasticity, and hypomyelination have also been linked to the major enzyme (ELOVL1). Recently, ELOVL1 has also been heavily used to treat a number of diseases. The current review focuses on in-depth unique insights regarding the role of ELOVL1 as a therapeutic target and associated neurological disorders.
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Affiliation(s)
- Arif Jamal Siddiqui
- Department
of Biology, College of Science, University
of Ha’il, P.O. Box 2440, Ha’il 81451, Saudi Arabia
- Molecular
Diagnostics and Personalized Therapeutics Unit, University of Ha’il, P.O. Box 2440, Ha’il 81451, Saudi Arabia
| | - Sadaf Jahan
- Department
of Medical Laboratory Sciences, College of Applied Medical Sciences, Majmaah University, Al Majmaah 11952, Saudi Arabia
| | - Swati Chaturvedi
- Department
of Pharmaceutics and Pharmacokinetics, Pre-Clinical North, Lab-106, CSIR-Central Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226031, India
| | - Maqsood Ahmed Siddiqui
- Department
of Zoology, College of Science, King Saud
University, P.O. Box 2455, Riyadh 11451, Kingdom of Saudi Arabia
| | - Mohammed Merae Alshahrani
- Department
of Clinical Laboratory Sciences, Faculty of Applied Medial Sciences, Najran University, P.O. Box 1988, Najran 61441, Saudi Arabia
| | - Abdelmushin Abdelgadir
- Department
of Biology, College of Science, University
of Ha’il, P.O. Box 2440, Ha’il 81451, Saudi Arabia
- Molecular
Diagnostics and Personalized Therapeutics Unit, University of Ha’il, P.O. Box 2440, Ha’il 81451, Saudi Arabia
| | - Walid Sabri Hamadou
- Department
of Biology, College of Science, University
of Ha’il, P.O. Box 2440, Ha’il 81451, Saudi Arabia
- Molecular
Diagnostics and Personalized Therapeutics Unit, University of Ha’il, P.O. Box 2440, Ha’il 81451, Saudi Arabia
| | - Juhi Saxena
- Department
of Biotechnology, University Institute of Biotechnology, Chandigarh University, Gharuan, NH-95, Chandigarh State Hwy, Ludhiana, Punjab 140413, India
| | - Bharath K. Sundararaj
- School
of Dental Medicine, Department of Cellular and Molecular Biology, Boston University, Medical Campus Boston, Boston, Massachusetts 02215, United States
| | - Mejdi Snoussi
- Department
of Biology, College of Science, University
of Ha’il, P.O. Box 2440, Ha’il 81451, Saudi Arabia
- Molecular
Diagnostics and Personalized Therapeutics Unit, University of Ha’il, P.O. Box 2440, Ha’il 81451, Saudi Arabia
| | - Riadh Badraoui
- Department
of Biology, College of Science, University
of Ha’il, P.O. Box 2440, Ha’il 81451, Saudi Arabia
- Molecular
Diagnostics and Personalized Therapeutics Unit, University of Ha’il, P.O. Box 2440, Ha’il 81451, Saudi Arabia
| | - Mohd Adnan
- Department
of Biology, College of Science, University
of Ha’il, P.O. Box 2440, Ha’il 81451, Saudi Arabia
- Molecular
Diagnostics and Personalized Therapeutics Unit, University of Ha’il, P.O. Box 2440, Ha’il 81451, Saudi Arabia
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3
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Gyening YK, Chauhan NK, Tytanic M, Ea V, Brush RS, Agbaga MP. ELOVL4 Mutations That Cause Spinocerebellar Ataxia-34 Differentially Alter Very Long Chain Fatty Acid Biosynthesis. J Lipid Res 2023; 64:100317. [PMID: 36464075 PMCID: PMC9823237 DOI: 10.1016/j.jlr.2022.100317] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 10/28/2022] [Accepted: 11/17/2022] [Indexed: 12/03/2022] Open
Abstract
The FA Elongase-4 (ELOVL4) enzyme mediates biosynthesis of both very long chain (VLC)-PUFAs and VLC-saturated FA (VLC-SFAs). VLC-PUFAs play critical roles in retina and sperm function, whereas VLC-SFAs are predominantly associated with brain function and maintenance of the skin permeability barrier. While some ELOVL4 mutations cause Autosomal Dominant Stargardt-like Macular Dystrophy (STGD3), other ELOVL4 point mutations, such as L168F and W246G, affect the brain and/or skin, leading to Spinocerebellar Ataxia-34 (SCA34) and Erythrokeratodermia variabilis. The mechanisms by which these ELOVL4 mutations alter VLC-PUFA and VLC-SFA biosynthesis to cause the different tissue-specific pathologies are not well understood. To understand how these mutations alter VLC-PUFA and VLC-SFA biosynthesis, we expressed WT-ELOVL4, L168F, and W246G ELOVL4 variants in cell culture and supplemented the cultures with VLC-PUFA or VLC-SFA precursors. Total lipids were extracted, converted to FA methyl esters, and quantified by gas chromatography. We showed that L168F and W246G mutants were capable of VLC-PUFA biosynthesis. W246G synthesized and accumulated 32:6n3, while L168F exhibited gain of function in VLC-PUFA biosynthesis as it made 38:5n3, which we did not detect in WT-ELOVL4 or W246G-expressing cells. However, compared with WT-ELOVL4, both L168F and W246G mutants were deficient in VLC-SFA biosynthesis, especially the W246G protein, which showed negligible VLC-SFA biosynthesis. These results suggest VLC-PUFA biosynthetic capabilities of L168F and W246G in the retina, which may explain the lack of retinal phenotype in SCA34. Defects in VLC-SFA biosynthesis by these variants may be a contributing factor to the pathogenic mechanism of SCA34 and Erythrokeratodermia variabilis.
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Affiliation(s)
- Yeboah Kofi Gyening
- Departments of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA; Department of Ophthalmology, Dean McGee Eye Institute, Oklahoma City, Oklahoma, USA
| | - Neeraj Kumar Chauhan
- Departments of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA; Department of Ophthalmology, Dean McGee Eye Institute, Oklahoma City, Oklahoma, USA
| | - Madison Tytanic
- Departments of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA; Department of Ophthalmology, Dean McGee Eye Institute, Oklahoma City, Oklahoma, USA
| | - Vicki Ea
- Department of Ophthalmology, Dean McGee Eye Institute, Oklahoma City, Oklahoma, USA
| | - Richard S Brush
- Department of Ophthalmology, Dean McGee Eye Institute, Oklahoma City, Oklahoma, USA; Departments of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Martin-Paul Agbaga
- Departments of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA; Department of Ophthalmology, Dean McGee Eye Institute, Oklahoma City, Oklahoma, USA; Departments of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA.
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4
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Yeboah GK, Lobanova ES, Brush RS, Agbaga MP. Very long chain fatty acid-containing lipids: a decade of novel insights from the study of ELOVL4. J Lipid Res 2021; 62:100030. [PMID: 33556440 PMCID: PMC8042400 DOI: 10.1016/j.jlr.2021.100030] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 01/12/2021] [Accepted: 01/27/2021] [Indexed: 11/18/2022] Open
Abstract
Lipids play essential roles in maintaining cell structure and function by modulating membrane fluidity and cell signaling. The fatty acid elongase-4 (ELOVL4) protein, expressed in retina, brain, Meibomian glands, skin, testes and sperm, is an essential enzyme that mediates tissue-specific biosynthesis of both VLC-PUFA and VLC-saturated fatty acids (VLC-SFA). These fatty acids play critical roles in maintaining retina and brain function, neuroprotection, skin permeability barrier maintenance, and sperm function, among other important cellular processes. Mutations in ELOVL4 that affect biosynthesis of these fatty acids cause several distinct tissue-specific human disorders that include blindness, age-related cerebellar atrophy and ataxia, skin disorders, early-childhood seizures, mental retardation, and mortality, which underscores the essential roles of ELOVL4 products for life. However, the mechanisms by which one tissue makes VLC-PUFA and another makes VLC-SFA, and how these fatty acids exert their important functional roles in each tissue, remain unknown. This review summarizes research over that last decade that has contributed to our current understanding of the role of ELOVL4 and its products in cellular function. In the retina, VLC-PUFA and their bioactive "Elovanoids" are essential for retinal function. In the brain, VLC-SFA are enriched in synaptic vesicles and mediate neuronal signaling by determining the rate of neurotransmitter release essential for normal neuronal function. These findings point to ELOVL4 and its products as being essential for life. Therefore, mutations and/or age-related epigenetic modifications of fatty acid biosynthetic gene activity that affect VLC-SFA and VLC-PUFA biosynthesis contribute to age-related dysfunction of ELOVL4-expressing tissues.
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Affiliation(s)
- Gyening Kofi Yeboah
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Ekaterina S Lobanova
- Department of Ophthalmology Research, University of Florida, Gainesville, FL, USA
| | - Richard S Brush
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Dean A. McGee Eye Institute, Oklahoma City, OK, USA
| | - Martin-Paul Agbaga
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA; Dean A. McGee Eye Institute, Oklahoma City, OK, USA.
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5
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Busik JV. Lipid metabolism dysregulation in diabetic retinopathy. J Lipid Res 2021; 62:100017. [PMID: 33581416 PMCID: PMC7892987 DOI: 10.1194/jlr.tr120000981] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 12/15/2020] [Accepted: 12/23/2020] [Indexed: 12/12/2022] Open
Abstract
Lipid metabolic abnormalities have emerged as potential risk factors for the development and progression of diabetic complications, including diabetic retinopathy (DR). This review article provides an overview of the results of clinical trials evaluating the potential benefits of lipid-lowering drugs, such as fibrates, omega-3 fatty acids, and statins, for the prevention and treatment of DR. Although several clinical trials demonstrated that treatment with fibrates leads to improvement of DR, there is a dissociation between the protective effects of fibrates in the retina, and the intended blood lipid classes, including plasma triglycerides, total cholesterol, or HDL:LDL cholesterol ratio. Guided by these findings, plasma lipid and lipoprotein-independent mechanisms are addressed based on clinical, cell culture, and animal model studies. Potential retinal-specific effects of fatty acid oxidation products, cholesterol, and ceramide, as well as lipid-independent effects of PPAR alpha activation, are summarized based on the current literature. Overall, this review highlights promising potential of lipid-based treatment strategies further enhanced by the new knowledge of intraretinal lipids and lipoproteins in DR.
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Affiliation(s)
- Julia V Busik
- Department of Physiology, Michigan State University, East Lansing, MI, USA.
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6
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Deák F, Anderson RE, Fessler JL, Sherry DM. Novel Cellular Functions of Very Long Chain-Fatty Acids: Insight From ELOVL4 Mutations. Front Cell Neurosci 2019; 13:428. [PMID: 31616255 PMCID: PMC6763723 DOI: 10.3389/fncel.2019.00428] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 09/06/2019] [Indexed: 12/22/2022] Open
Abstract
Elongation of Very Long chain fatty acids-4 (ELOVL4) protein is a member of the ELOVL family of fatty acid elongases that is collectively responsible for catalyzing formation of long chain fatty acids. ELOVL4 is the only family member that catalyzes production of Very Long Chain Saturated Fatty Acids (VLC-SFA) and Very Long Chain Polyunsaturated Fatty Acids (VLC-PUFA) with chain lengths ≥28 carbons. ELOVL4 and its VLC-SFA and VLC-PUFA products are emerging as important regulators of synaptic signaling and neuronal survival in the central nervous system (CNS). Distinct sets of mutations in ELOVL4 cause three different neurological diseases in humans. Heterozygous inheritance of one set of autosomal dominant ELOVL4 mutations that leads to truncation of the ELOVL4 protein causes Stargardt-like macular dystrophy (STGD3), an aggressive juvenile-onset retinal degeneration. Heterozygous inheritance of a different set of autosomal dominant ELOVL4 mutations that leads to a full-length protein with single amino acid substitutions causes spinocerebellar ataxia 34 (SCA34), a late-onset neurodegenerative disease characterized by gait ataxia and cerebellar atrophy. Homozygous inheritance of a different set of ELOVL4 mutations causes a more severe disease with infantile onset characterized by seizures, spasticity, intellectual disability, ichthyosis, and premature death. ELOVL4 is expressed widely in the CNS and is found primarily in neurons. ELOVL4 is expressed in cell-specific patterns within different regions of the CNS that are likely to be related to disease symptoms. In the retina, ELOVL4 is expressed exclusively in photoreceptors and produces VLC-PUFA that are incorporated into phosphatidylcholine and enriched in the light sensitive membrane disks of the photoreceptor outer segments. VLC-PUFA are enzymatically converted into "elovanoid" compounds that appear to provide paracrine signals that promote photoreceptor and neuronal survival. In the brain, the main ELOVL4 products are VLC-SFA that are incorporated into sphingolipids and enriched in synaptic vesicles, where they regulate kinetics of presynaptic neurotransmitter release. Understanding the function of ELOVL4 and its VLC-SFA and VLC-PUFA products will advance our understanding of basic mechanisms in neural signaling and has potential for developing novel therapies for seizure and neurodegenerative diseases.
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Affiliation(s)
- Ferenc Deák
- Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Oklahoma Center for Neurosciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Robert E Anderson
- Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Oklahoma Center for Neurosciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Jennifer L Fessler
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - David M Sherry
- Oklahoma Center for Neurosciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Department of Pharmaceutical Sciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
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7
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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: 54] [Impact Index Per Article: 7.7] [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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8
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Kanan Y, Gordon WC, Mukherjee PK, Bazan NG, Al-Ubaidi MR. Neuroprotectin D1 is synthesized in the cone photoreceptor cell line 661W and elicits protection against light-induced stress. Cell Mol Neurobiol 2014; 35:197-204. [PMID: 25212825 DOI: 10.1007/s10571-014-0111-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2014] [Accepted: 09/01/2014] [Indexed: 12/31/2022]
Abstract
Docosahexaenoic acid (DHA), an omega-3 fatty acid family member, is obtained by diet or synthesized from dietary essential omega-3 linolenic acid and delivered systemically to the choriocapillaris, from where it is taken up by the retinal pigment epithelium (RPE). DHA is then transported to the inner segments of photoreceptors, where it is incorporated in phospholipids during the biogenesis of outer segment disk and plasma membranes. As apical photoreceptor disks are gradually shed and phagocytized by the RPE, DHA is retrieved and recycled back to photoreceptor inner segments for reassembly into new disks. Under uncompensated oxidative stress, the docosanoid neuroprotectin D1 (NPD1), a potent mediator derived from DHA, is formed by the RPE and displays its bioactivity in an autocrine and paracrine fashion. The purpose of this study was to determine whether photoreceptors have the ability to synthesize NPD1, and whether or not this lipid mediator exerts bioactivity on these cells. For this purpose, 661W cells (mouse-derived photoreceptor cells) were used. First we asked whether these cells have the ability to form NPD1 by incubating cells with deuterium (d4)-labeled DHA exposed to dark and bright light treatments, followed by LC-MS/MS-based lipidomic analysis to identify and quantify d4-NPD1. The second question pertains to the potential bioactivity of these lipids. Therefore, cells were incubated with 9-cis-retinal in the presence of bright light that triggers cell damage and death. Following 9-cis-retinal loading, DHA, NPD1, or vehicle were added to the media and the 661W cells maintained either in darkness or under bright light. DHA and NPD1 were then quantified in cells and media. Regardless of lighting conditions, 661W cells acquired DHA from the media and synthesized 4-9 times as much d4-NPD1 under bright light treatment in the absence and presence of 9-cis-retinal compared to cells in darkness. Viability assays of 9-cis-retinal-treated cells demonstrated that 34 % of the cells survived without DHA or NPD1. However, after bright light exposure, DHA protected 23 % above control levels and NPD1 increased protection by 32 %. In conclusion, the photoreceptor cell line 661W has the capability to synthesize NPD1 from DHA when under stress, and, in turn, can be protected from stress-induced apoptosis by DHA or NPD1, indicating that photoreceptors effectively contribute to endogenous protective signaling mediated by NPD1 under stressful conditions.
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Affiliation(s)
- Y Kanan
- Department of Cell Biology, University of Oklahoma Health Sciences Center, BMSB 781, 940 Stanton L. Young Blvd., Oklahoma City, OK, 73104, USA
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9
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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: 17] [Impact Index Per Article: 1.5] [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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10
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Lipid composition of the human eye: are red blood cells a good mirror of retinal and optic nerve fatty acids? PLoS One 2012; 7:e35102. [PMID: 22496896 PMCID: PMC3322172 DOI: 10.1371/journal.pone.0035102] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Accepted: 03/08/2012] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND The assessment of blood lipids is very frequent in clinical research as it is assumed to reflect the lipid composition of peripheral tissues. Even well accepted such relationships have never been clearly established. This is particularly true in ophthalmology where the use of blood lipids has become very common following recent data linking lipid intake to ocular health and disease. In the present study, we wanted to determine in humans whether a lipidomic approach based on red blood cells could reveal associations between circulating and tissue lipid profiles. To check if the analytical sensitivity may be of importance in such analyses, we have used a double approach for lipidomics. METHODOLOGY AND PRINCIPAL FINDINGS Red blood cells, retinas and optic nerves were collected from 9 human donors. The lipidomic analyses on tissues consisted in gas chromatography and liquid chromatography coupled to an electrospray ionization source-mass spectrometer (LC-ESI-MS). Gas chromatography did not reveal any relevant association between circulating and ocular fatty acids except for arachidonic acid whose circulating amounts were positively associated with its levels in the retina and in the optic nerve. In contrast, several significant associations emerged from LC-ESI-MS analyses. Particularly, lipid entities in red blood cells were positively or negatively associated with representative pools of retinal docosahexaenoic acid (DHA), retinal very-long chain polyunsaturated fatty acids (VLC-PUFA) or optic nerve plasmalogens. CONCLUSIONS AND SIGNIFICANCE LC-ESI-MS is more appropriate than gas chromatography for lipidomics on red blood cells, and further extrapolation to ocular lipids. The several individual lipid species we have identified are good candidates to represent circulating biomarkers of ocular lipids. However, further investigation is needed before considering them as indexes of disease risk and before using them in clinical studies on optic nerve neuropathies or retinal diseases displaying photoreceptors degeneration.
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Yu M, Benham A, Logan S, Brush RS, Mandal MNA, Anderson RE, Agbaga MP. ELOVL4 protein preferentially elongates 20:5n3 to very long chain PUFAs over 20:4n6 and 22:6n3. J Lipid Res 2012; 53:494-504. [PMID: 22158834 PMCID: PMC3276472 DOI: 10.1194/jlr.m021386] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We hypothesized that reduction/loss of very long chain PUFAs (VLC-PUFAs) due to mutations in the ELOngase of very long chain fatty acid-4 (ELOVL4) protein contributes to retinal degeneration in autosomal dominant Stargardt-like macular dystrophy (STGD3) and age-related macular degeneration; hence, increasing VLC-PUFA in the retina of these patients could provide some therapeutic benefits. Thus, we tested the efficiency of elongation of C20-C22 PUFA by the ELOVL4 protein to determine which substrates are the best precursors for biosynthesis of VLC-PUFA. The ELOVL4 protein was expressed in pheochromocytoma cells, while green fluorescent protein-expressing and nontransduced cells served as controls. The cells were treated with 20:5n3, 22:6n3, and 20:4n6, either individually or in equal combinations. Both transduced and control cells internalized and elongated the supplemented FAs to C22-C26 precursors. Only ELOVL4-expressing cells synthesized C28-C38 VLC-PUFA from these precursors. In general, 20:5n3 was more efficiently elongated to VLC-PUFA in the ELOVL4-expressing cells, regardless of whether it was in combination with 22:6n3 or with 20:4n6. In each FA treatment group, C34 and C36 VLC-PUFAs were the predominant VLC-PUFAs in the ELOVL4-expressing cells. In summary, 20:5n3, followed by 20:4n6, seems to be the best precursor for boosting the synthesis of VLC-PUFA by ELOVL4 protein.
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Affiliation(s)
- Man Yu
- Departments of Ophthalmology and Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK; Ophthalmic Laboratories and Department of Ophthalmology, West China Hospital, Sichuan University, P. R. China
| | - Aaron Benham
- Departments of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK; Dean McGee Eye Institute, Oklahoma City, OK; and
| | - Sreemathi Logan
- Departments of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK; Departments of Ophthalmology and Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK; Dean McGee Eye Institute, Oklahoma City, OK; and
| | - R Steven Brush
- Departments of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK; Dean McGee Eye Institute, Oklahoma City, OK; and
| | - Md Nawajes A Mandal
- Departments of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK; Dean McGee Eye Institute, Oklahoma City, OK; and
| | - Robert E Anderson
- Departments of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK; Departments of Ophthalmology and Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK; Dean McGee Eye Institute, Oklahoma City, OK; and
| | - Martin-Paul Agbaga
- Departments of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK; Dean McGee Eye Institute, Oklahoma City, OK; and.
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Liu A, Lin Y, Terry R, Nelson K, Bernstein PS. Role of long-chain and very-long-chain polyunsaturated fatty acids in macular degenerations and dystrophies. ACTA ACUST UNITED AC 2011; 6:593-613. [PMID: 25324899 DOI: 10.2217/clp.11.41] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Macular degeneration is a progressive, bilateral eye disorder that damages the macula of the human eye. The most common form of macular degeneration is age-related macular degeneration (AMD), which is the leading cause of irreversible blindness in people older than 50 years in developed countries. Autosomal dominant Stargardt disease-3 (STGD3) is an inherited macular dystrophy that has clinical features similar to dry AMD, but occurs at a much earlier age. It is caused by a mutation in the elongation of very-long-chain fatty acids-like 4 (ELOVL4) gene, which is responsible for encoding the elongase enzyme that converts shorter chain fatty acids into C28-C38 very long-chain polyunsaturated fatty acids (VLCPUFAs, total number of carbons ≥24). Diets rich in long-chain polyunsaturated fatty acids (LCPUFAs) have inverse associations with the progression of AMD and STGD3, and a deficiency in retinal LCPUFAs and VLCPUFAs has been detected in AMD retinas and STGD3 animal models. This article systematically summarizes the roles of LCPUFAs and VLCPUFAs in AMD and STGD3, and discusses future research directions.
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Affiliation(s)
- Aihua Liu
- Department of Ophthalmology and Visual Sciences, 65 Mario Capecchi Drive, Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Yanhua Lin
- Department of Ophthalmology and Visual Sciences, 65 Mario Capecchi Drive, Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Ryan Terry
- Department of Ophthalmology and Visual Sciences, 65 Mario Capecchi Drive, Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Kelly Nelson
- Department of Ophthalmology and Visual Sciences, 65 Mario Capecchi Drive, Moran Eye Center, University of Utah School of Medicine, 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 School of Medicine, Salt Lake City, UT 84132, USA
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Carmona-Antoñanzas G, Monroig Ó, Dick JR, Davie A, Tocher DR. Biosynthesis of very long-chain fatty acids (C>24) in Atlantic salmon: Cloning, functional characterisation, and tissue distribution of an Elovl4 elongase. Comp Biochem Physiol B Biochem Mol Biol 2011; 159:122-9. [DOI: 10.1016/j.cbpb.2011.02.007] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 02/28/2011] [Accepted: 02/28/2011] [Indexed: 02/05/2023]
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Jastrzebska B, Debinski A, Filipek S, Palczewski K. Role of membrane integrity on G protein-coupled receptors: Rhodopsin stability and function. Prog Lipid Res 2011; 50:267-77. [PMID: 21435354 DOI: 10.1016/j.plipres.2011.03.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Rhodopsin is a prototypical G protein-coupled receptor (GPCR) - a member of the superfamily that shares a similar structural architecture consisting of seven-transmembrane helices and propagates various signals across biological membranes. Rhodopsin is embedded in the lipid bilayer of specialized disk membranes in the outer segments of retinal rod photoreceptor cells where it transmits a light-stimulated signal. Photoactivated rhodopsin then activates a visual signaling cascade through its cognate G protein, transducin or Gt, that results in a neuronal response in the brain. Interestingly, the lipid composition of ROS membranes not only differs from that of the photoreceptor plasma membrane but is critical for visual transduction. Specifically, lipids can modulate structural changes in rhodopsin that occur after photoactivation and influence binding of transducin. Thus, altering the lipid organization of ROS membranes can result in visual dysfunction and blindness.
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Affiliation(s)
- Beata Jastrzebska
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4965, USA.
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