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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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Piotter E, McClements ME, MacLaren RE. Therapy Approaches for Stargardt Disease. Biomolecules 2021; 11:1179. [PMID: 34439845 PMCID: PMC8393614 DOI: 10.3390/biom11081179] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 07/27/2021] [Accepted: 08/05/2021] [Indexed: 12/14/2022] Open
Abstract
Despite being the most prevalent cause of inherited blindness in children, Stargardt disease is yet to achieve the same clinical trial success as has been achieved for other inherited retinal diseases. With an early age of onset and continual progression of disease over the life course of an individual, Stargardt disease appears to lend itself to therapeutic intervention. However, the aetiology provides issues not encountered with the likes of choroideremia and X-linked retinitis pigmentosa and this has led to a spectrum of treatment strategies that approach the problem from different aspects. These include therapeutics ranging from small molecules and anti-sense oligonucleotides to viral gene supplementation and cell replacement. The advancing development of CRISPR-based molecular tools is also likely to contribute to future therapies by way of genome editing. In this we review, we consider the most recent pre-clinical and clinical trial data relating to the different strategies being applied to the problem of generating a treatment for the large cohort of Stargardt disease patients worldwide.
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Affiliation(s)
- Elena Piotter
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK; (E.P.); (M.E.M.)
- Oxford University Hospitals NHS Foundation Trust NIHR Biomedical Research Centre, Oxford OX3 9DU, UK
| | - Michelle E McClements
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK; (E.P.); (M.E.M.)
- Oxford University Hospitals NHS Foundation Trust NIHR Biomedical Research Centre, Oxford OX3 9DU, UK
| | - Robert E MacLaren
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK; (E.P.); (M.E.M.)
- Oxford University Hospitals NHS Foundation Trust NIHR Biomedical Research Centre, Oxford OX3 9DU, UK
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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: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [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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Mueller N, Sassa T, Morales-Gonzalez S, Schneider J, Salchow DJ, Seelow D, Knierim E, Stenzel W, Kihara A, Schuelke M. De novo mutation in ELOVL1 causes ichthyosis, acanthosis nigricans, hypomyelination, spastic paraplegia, high frequency deafness and optic atrophy. J Med Genet 2018; 56:164-175. [PMID: 30487246 DOI: 10.1136/jmedgenet-2018-105711] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 11/07/2018] [Accepted: 11/13/2018] [Indexed: 12/21/2022]
Abstract
BACKGROUND Very long-chain fatty acids (VLCFAs) are essential for functioning of biological membranes. ELOVL fatty acid elongase 1 catalyses elongation of saturated and monounsaturated C22-C26-VLCFAs. We studied two patients with a dominant ELOVL1 mutation. Independently, Kutkowska-Kaźmierczak et al. had investigated the same patients and found the same mutation. We extended our study towards additional biochemical, functional, and therapeutic aspects. METHODS We did mutation screening by whole exome sequencing. RNA-sequencing was performed in patient and control fibroblasts. Ceramide and sphingomyelin levels were measured by LC-MS/MS. ELOVL1 activity was determined by a stable isotope-labelled [13C]malonyl-CoA elongation assay. ELOVL1 expression patterns were investigated by immunofluorescence, in situ hybridisation and RT-qPCR. As treatment option, we investigated VLCFA loading of fibroblasts. RESULTS Both patients carried an identical heterozygous de novo ELOVL1 mutation (c.494C>T, NM_001256399; p.S165F) not deriving from a founder allele. Patients suffered from epidermal hyperproliferation and increased keratinisation (ichthyosis). Hypomyelination of the central white matter explained spastic paraplegia and central nystagmus, while optic atrophy was causative for reduction of peripheral vision and visual acuity. The mutation abrogated ELOVL1 enzymatic activity and reduced ≥C24 ceramides and sphingomyelins in patient cells. Fibroblast loading with C22:0-VLCFAs increased C24:0-ceramides and sphingomyelins. We found competitive inhibition for ceramide and sphingomyelin synthesis between saturated and monounsaturated VLCFAs. Transcriptome analysis revealed upregulation of modules involved in epidermal development and keratinisation, and downregulation of genes for neurodevelopment, myelination, and synaptogenesis. Many regulated genes carried consensus proliferator-activated receptor (PPAR)α and PPARγ binding motifs in their 5'-regions. CONCLUSION A dominant ELOVL1 mutation causes a neuro-ichthyotic disorder possibly amenable to treatment with PPAR-modulating drugs.
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Affiliation(s)
- Noomi Mueller
- NeuroCure Clinical Research Center, Charité-Universitätsmedizin Berlin, Berlin, Germany.,Department of Neuropediatrics, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Takayuki Sassa
- Faculty of Pharmaceutical Sciences, Laboratory of Biochemistry, Hokkaido University, Sapporo, Japan
| | | | - Joanna Schneider
- Department of Neuropediatrics, Charité-Universitätsmedizin Berlin, Berlin, Germany.,Berlin Institute of Health, Berlin, Germany
| | - Daniel J Salchow
- Department of Ophthalmology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Dominik Seelow
- NeuroCure Clinical Research Center, Charité-Universitätsmedizin Berlin, Berlin, Germany.,Berlin Institute of Health, Berlin, Germany
| | - Ellen Knierim
- NeuroCure Clinical Research Center, Charité-Universitätsmedizin Berlin, Berlin, Germany.,Department of Neuropediatrics, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Werner Stenzel
- Institute of Neuropathology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Akio Kihara
- Faculty of Pharmaceutical Sciences, Laboratory of Biochemistry, Hokkaido University, Sapporo, Japan
| | - Markus Schuelke
- NeuroCure Clinical Research Center, Charité-Universitätsmedizin Berlin, Berlin, Germany.,Department of Neuropediatrics, Charité-Universitätsmedizin Berlin, Berlin, Germany
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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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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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Ding XQ, Thapa A, Ma H, Xu J, Elliott MH, Rodgers KK, Smith ML, Wang JS, Pittler SJ, Kefalov VJ. The B3 Subunit of the Cone Cyclic Nucleotide-gated Channel Regulates the Light Responses of Cones and Contributes to the Channel Structural Flexibility. J Biol Chem 2016; 291:8721-34. [PMID: 26893377 DOI: 10.1074/jbc.m115.696138] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2015] [Indexed: 11/06/2022] Open
Abstract
Cone photoreceptor cyclic nucleotide-gated (CNG) channels play a pivotal role in cone phototransduction, which is a process essential for daylight vision, color vision, and visual acuity. Mutations in the cone channel subunits CNGA3 and CNGB3 are associated with human cone diseases, including achromatopsia, cone dystrophies, and early onset macular degeneration. Mutations in CNGB3 alone account for 50% of reported cases of achromatopsia. This work investigated the role of CNGB3 in cone light response and cone channel structural stability. As cones comprise only 2-3% of the total photoreceptor population in the wild-type mouse retina, we used Cngb3(-/-)/Nrl(-/-) mice with CNGB3 deficiency on a cone-dominant background in our study. We found that, in the absence of CNGB3, CNGA3 was able to travel to the outer segments, co-localize with cone opsin, and form tetrameric complexes. Electroretinogram analyses revealed reduced cone light response amplitude/sensitivity and slower response recovery in Cngb3(-/-)/Nrl(-/-) mice compared with Nrl(-/-) mice. Absence of CNGB3 expression altered the adaptation capacity of cones and severely compromised function in bright light. Biochemical analysis demonstrated that CNGA3 channels lacking CNGB3 were more resilient to proteolysis than CNGA3/CNGB3 channels, suggesting a hindered structural flexibility. Thus, CNGB3 regulates cone light response kinetics and the channel structural flexibility. This work advances our understanding of the biochemical and functional role of CNGB3 in cone photoreceptors.
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Affiliation(s)
| | | | - Hongwei Ma
- From the Departments of Cell Biology and
| | - Jianhua Xu
- From the Departments of Cell Biology and
| | - Michael H Elliott
- Ophthalmology and Dean McGee Eye Institute, Oklahoma City, Oklahoma 73104
| | - Karla K Rodgers
- Biochemistry, University of Oklahoma Health Sciences Center and
| | - Marci L Smith
- Department of Vision Sciences, University of Alabama, Birmingham, Alabama 35924, and
| | - Jin-Shan Wang
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, Missouri 63110
| | - Steven J Pittler
- Department of Vision Sciences, University of Alabama, Birmingham, Alabama 35924, and
| | - Vladimir J Kefalov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, Missouri 63110
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Agbaga MP. Different Mutations in ELOVL4 Affect Very Long Chain Fatty Acid Biosynthesis to Cause Variable Neurological Disorders in Humans. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 854:129-35. [PMID: 26427403 DOI: 10.1007/978-3-319-17121-0_18] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
All mammalian cell membranes are characterized by amphipathic lipid molecules that interact with proteins to confer structural and functional properties on the cell. The predominant lipid species are phospholipids, glycolipids, sphingolipids and cholesterol. These lipids contain fatty acids with variable hydrocarbon chain lengths between C14-C40, either saturated or unsaturated, that are derived from diet, synthesized de novo, or elongated from shorter chain fatty acids by fatty acid elongase enzymes. One member of the family of elongases, ELOngation of Very Long chain fatty acids-4 (ELOVL4), mediates the biosynthesis of both saturated and unsaturated very long chain fatty acids (VLC-FA; > C26) in the retina, meibomian gland, brain, skin, and testis. Different mutations in ELOVL4 cause tissue-specific maculopathy and/or neuro-ichthyotic disorders. The goal of this mini-review is to highlight how different mutations in ELOVL4 can cause variable phenotypic disorder, and propose a possible mechanism, based on the role of fatty acids in membranes, which could explain the different phenotypes.
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Affiliation(s)
- Martin-Paul Agbaga
- Department of Ophthalmology, Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd., DMEI 429PB, 73104, Oklahoma City, OK, USA.
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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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10
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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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11
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Samardzija M, Grimm C. Mouse models for cone degeneration. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 801:567-73. [PMID: 24664745 DOI: 10.1007/978-1-4614-3209-8_72] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Loss of cone vision has devastating effects on everyday life. Even though much effort has been made to understand cone physiology and pathophysiology, no successful therapies are available for patients suffering from cone disorders. As complex retinal interactions cannot be studied in vitro, utilization of different animal models is inevitable. Due to recent advances in transgenesis, mice became the most popular animal model to study human diseases, also in ophthalmology. While there are similarities in retinal anatomy and pathophysiology between mice and humans, there are also differences, most importantly the lack of a cone-rich macula in mice. Instead, cones in mice are rare and distributed over the whole retina, which makes the analysis of cone pathophysiology very difficult in these animals. This hindrance is one of the reasons why our understanding of rod pathophysiological processes is much more advanced. Recently, however, the sparseness of cones was overcome by the generation of the Nrl (- / -) mouse that expresses only cone photoreceptors in the retina. This paper will give a brief overview of some of the known mouse models to study cone degeneration and discuss the current knowledge gained from the analysis of these models.
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Affiliation(s)
- Marijana Samardzija
- Lab for Retinal Cell Biology, Department of Ophthalmology, University of Zurich, Wagistr 14 Schlieren, 8952, Zurich, Switzerland,
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12
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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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McMahon A, Lu H, Butovich IA. A role for ELOVL4 in the mouse meibomian gland and sebocyte cell biology. Invest Ophthalmol Vis Sci 2014; 55:2832-40. [PMID: 24677106 DOI: 10.1167/iovs.13-13335] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE The meibum lipidome contains lipids with extremely long chain fatty acid (ELCFA) residues, longer than C28. Particular lipids based on extremely long chain (O-acyl)-ω-hydroxy fatty acids (OAHFA) are found in all mammal meibum and are proposed to stabilize the tear film by forming the interphase between its lipid and aqueous sublayers. The enzyme ELOVL4 is required for synthesis of ELCFA. We investigated whether Stgd3 mice, harboring mutations in ELOVL4 that have been shown to decrease the levels of its biosynthetic lipid products, would represent a model system in which to define the role of such lipids in meibum. METHODS Ocular phenotypes of wild-type mice were compared with those of Stgd3 mice. ELOVL4 expression in eyelid and back skin was characterized by immunohistochemical analysis. Anatomical changes within the eyelids of mutant mice were examined by hematoxylin and eosin staining of paraffin-embedded tissue. RESULTS Mutant mice had increased eyelid blink rates, a reluctance to maintain their eyes fully open, protruding meibomian gland (MG) orifices, and anatomical changes within the MG. In wild-type mice, ELOVL4 was strongly expressed within the holocrine meibomian and sebaceous glands. The enzyme localized to structures encircling lipid deposits within cells in both the early and late stages of differentiation. No ELOVL4 was detected within the central meibomian duct. CONCLUSIONS Stgd3 mice show changes that resemble clinical findings in patients with the evaporative type of dry eye disease, suggesting that further studies in this mouse model will provide a basis for better understanding of the causes of human dry eye.
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Affiliation(s)
- Anne McMahon
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, United States
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15
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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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Marchette L, Sherry D, Brush RS, Chan M, Wen Y, Wang J, Ash JD, Anderson RE, Mandal NA. Very long chain polyunsaturated fatty acids and rod cell structure and function. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 801:637-45. [PMID: 24664753 PMCID: PMC4456017 DOI: 10.1007/978-1-4614-3209-8_80] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
The gene encoding Elongation of Very Long Chain Fatty Acids-4 (ELOVL4) is mutated in patients with autosomal dominant Stargardt's Macular Dystrophy Type 3 (STDG3). ELOVL4 catalyzes the initial condensation step in the elongation of polyunsaturated fatty acids (PUFA) containing more than 26 carbons (26C) to very long chain PUFA (VLC-PUFA; C28 and greater). To investigate the role of VLC-PUFA in rod photoreceptors, we generated mice with rod-specific deletion of Elovl4 (RcKO). The mosaic deletion of rod-expressed ELOVL4 protein resulted in a 36 % lower amount of VLC-PUFA in the retinal phosphatidylcholine (PC) fraction compared to retinas from wild-type mice. However, this reduction was not sufficient to cause rod dysfunction at 7 months or photoreceptor degeneration at 9 or 15 months.
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Affiliation(s)
- L.D. Marchette
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd., Oklahoma City, OK 73104, USA
| | - D.M Sherry
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Department of Pharmaceutical Sciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - R. S Brush
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd., Oklahoma City, OK 73104, USA
| | - M. Chan
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd., Oklahoma City, OK 73104, USA
| | - Y. Wen
- Amherst College, Amherst, MA, USA
| | - J. Wang
- University of Florida, Gainesville, FL, USA
| | | | - Robert E. Anderson
- 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; Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd., Oklahoma City, OK 73104, USA
| | - N. A. Mandal
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd., Oklahoma City, OK 73104, USA
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Site-directed mutagenesis of a fatty acid elongase ELO-like condensing enzyme. FEBS Lett 2013; 587:3837-42. [PMID: 24157363 DOI: 10.1016/j.febslet.2013.10.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 10/08/2013] [Accepted: 10/12/2013] [Indexed: 11/22/2022]
Abstract
The condensation step of fatty acid elongation is the addition of a C2 unit from malonyl-CoA to an acyl primer catalyzed by one of two families of enzymes, the 3-ketoacyl-CoA synthases and the ELO-like condensing enzymes. 3-Ketoacyl-CoA synthases use a Claisen-like reaction mechanism while the mechanism of the ELO-catalyzed condensation reaction is unknown. We have used site-directed mutagenesis of Dictyostelium discoideum EloA to identify residues important to catalytic activity and/or structure. Mutation of highly conserved polar residues to alanine resulted in an inactive enzyme strongly suggesting that these residues play a role in the condensation reaction.
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Chavali VRM, Vasireddy V, Ayyagari R. Silencing the expression of CTRP5/C1QTNF5 and ELOVL4 genes by small interfering RNA. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 723:225-33. [PMID: 22183337 DOI: 10.1007/978-1-4614-0631-0_30] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Recessive mutations in ELOVL4 cause ichthyosis, intellectual disability, and spastic quadriplegia. Am J Hum Genet 2011; 89:745-50. [PMID: 22100072 DOI: 10.1016/j.ajhg.2011.10.011] [Citation(s) in RCA: 138] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Revised: 10/20/2011] [Accepted: 10/26/2011] [Indexed: 12/21/2022] Open
Abstract
Very-long-chain fatty acids (VLCFAs) play important roles in membrane structure and cellular signaling, and their contribution to human health is increasingly recognized. Fatty acid elongases catalyze the first and rate-limiting step in VLCFA synthesis. Heterozygous mutations in ELOVL4, the gene encoding one of the elongases, are known to cause macular degeneration in humans and retinal abnormalities in mice. However, biallelic ELOVL4 mutations have not been observed in humans, and murine models with homozygous mutations die within hours of birth as a result of a defective epidermal water barrier. Here, we report on two human individuals with recessive ELOVL4 mutations revealed by a combination of autozygome analysis and exome sequencing. These individuals exhibit clinical features of ichthyosis, seizures, mental retardation, and spasticity-a constellation that resembles Sjögren-Larsson syndrome (SLS) but presents a more severe neurologic phenotype. Our findings identify recessive mutations in ELOVL4 as the cause of a neuro-ichthyotic disease and emphasize the importance of VLCFA synthesis in brain and cutaneous development.
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20
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Chiou GC. Pharmacological treatment of dry age-related macular degeneration (AMD). Taiwan J Ophthalmol 2011. [DOI: 10.1016/j.tjo.2011.08.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
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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: 0.7] [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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Xu J, Morris L, Fliesler SJ, Sherry DM, Ding XQ. Early-onset, slow progression of cone photoreceptor dysfunction and degeneration in CNG channel subunit CNGB3 deficiency. Invest Ophthalmol Vis Sci 2011; 52:3557-66. [PMID: 21273547 DOI: 10.1167/iovs.10-6358] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
PURPOSE To investigate the progression of cone dysfunction and degeneration in CNG channel subunit CNGB3 deficiency. METHODS Retinal structure and function in CNGB3(-/-) and wild-type (WT) mice were evaluated by electroretinography (ERG), lectin cytochemistry, and correlative Western blot analysis of cone-specific proteins. Cone and rod terminal integrity was assessed by electron microscopy and synaptic protein immunohistochemical distribution. RESULTS Cone ERG amplitudes (photopic b-wave) in CNGB3(-/-) mice were reduced to approximately 50% of WT levels by postnatal day 15, decreasing further to approximately 30% of WT levels by 1 month and to approximately 20% by 12 months of age. Rod ERG responses (scotopic a-wave) were not affected in CNGB3(-/-) mice. Average CNGB3(-/-) cone densities were approximately 80% of WT levels at 1 month and declined slowly thereafter to only approximately 50% of WT levels by 12 months. Expression levels of M-opsin, cone transducin α-subunit, and cone arrestin in CNGB3(-/-) mice were reduced by 50% to 60% by 1 month and declined to 35% to 45% of WT levels by 9 months. In addition, cone opsin mislocalized to the outer nuclear layer and the outer plexiform layer in the CNGB3(-/-) retina. Cone and rod synaptic marker expression and terminal ultrastructure were normal in the CNGB3(-/-) retina. CONCLUSIONS These findings are consistent with an early-onset, slow progression of cone functional defects and cone loss in CNGB3(-/-) mice, with the cone signaling deficits arising from disrupted phototransduction and cone loss rather than from synaptic defects.
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Affiliation(s)
- Jianhua Xu
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
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Berdeaux O, Juaneda P, Martine L, Cabaret S, Bretillon L, Acar N. Identification and quantification of phosphatidylcholines containing very-long-chain polyunsaturated fatty acid in bovine and human retina using liquid chromatography/tandem mass spectrometry. J Chromatogr A 2010; 1217:7738-48. [PMID: 21035124 DOI: 10.1016/j.chroma.2010.10.039] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Revised: 09/09/2010] [Accepted: 10/07/2010] [Indexed: 11/30/2022]
Abstract
The retina is one of the vertebrate tissues with the highest content in polyunsaturated fatty acids (PUFA). A large proportion of retinal phospholipids, especially those found in photoreceptor membranes, are dipolyunsaturated molecular species. Among them, dipolyunsaturated phosphatidylcholine (PC) molecular species are known to contain very-long-chain polyunsaturated fatty acids (VLC-PUFA) from the n-3 and n-6 series having 24-36 carbon atoms (C24-C36) and four to six double bonds. Recent interest in the role played by VLC-PUFA arose from the findings that a protein called elongation of very-long-chain fatty acids 4 (ELOVL4) is involved in their biosynthesis and that mutations in the ELOVL4 gene are associated with Stargardt-like macular dystrophy (STD3), a dominantly inherited juvenile macular degeneration leading to vision loss. The aim of the present study was to develop an HPLC-ESI-MS/MS method for the structural characterisation and the quantification of dipolyunsaturated PC molecular species containing VLC-PUFA and validate this methodology on retinas from bovines and human donors. Successful separation of phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylserine (PS), PC, lyso-phosphatidylcholine (LPC) and sphingomyelin (SM) was achieved using a silica gel column and a gradient of hexane/isopropanol/water containing ammonium formate as a mobile phase. A complete structural characterisation of intact phosphatidylcholine species was obtained by collision-induced dissociation (CID) in the negative mode. Fatty acid composition and distribution can be clearly assigned based on the intensity of sn-2/sn-1 fragment ions. The PC species were characterised on bovine retina, 28 of which were dipolyunsaturated PC species containing one VLC-PUFA (C24-C36) with three to six double bonds. VLC-PUFA was always in the sn-1 position while PUFA at the sn-2 position was exclusively docosahexaenoic acid (DHA, C22:6n-3). Most of these VLC-PUFA-containing dipolyunsaturated PCs were detected and quantified in human retinas. The quantitative analysis of the different PC molecular species was performed in the positive mode using precursor ion scanning of m/z 184 and 14:0/14:0-PC and 24:0/24:0-PC as internal standards. The relationship between the MS peak intensities of different PC species and their carbon chain length was included for calibration. The main compounds represented were those having VLC-PUFA with 32 carbon atoms (C32:3, C32:4, C32:5 and C32:6) and 34 carbon atoms (C34:3, C34:4, C34:5 and C34:6). Dipolyunsaturated PCs with 36:5 and 36:6 were detected but in smaller quantities. In conclusion, this new HPLC-ESI-MS/MS method is sensitive and specific enough to structurally characterise and quantify all molecular PC species, including those esterified with VLC-PUFA. This technique is valuable for a precise characterisation of PC molecular species containing VLC-PUFA in retina and may be useful for a better understanding of the pathogenesis of STD3.
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Affiliation(s)
- Olivier Berdeaux
- Lipid-Aroma Platform, Centre des Sciences du Goût et de l'Alimentation, UMR6265 CNRS, UMR1324 INRA, Université de Bourgogne, Agrosup Dijon, F-21000 Dijon, France.
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Molday RS, Zhang K. Defective lipid transport and biosynthesis in recessive and dominant Stargardt macular degeneration. Prog Lipid Res 2010; 49:476-92. [PMID: 20633576 DOI: 10.1016/j.plipres.2010.07.002] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Stargardt disease is a common inherited macular degeneration characterized by a significant loss in central vision in the first or second decade of life, bilateral atrophic changes in the central retina associated with degeneration of photoreceptors and underlying retinal pigment epithelial cells, and the presence of yellow flecks extending from the macula. Autosomal recessive Stargardt disease, the most common macular dystrophy, is caused by mutations in the gene encoding ABCA4, a photoreceptor ATP binding cassette (ABC) transporter. Biochemical studies together with analysis of abca4 knockout mice and Stargardt patients have implicated ABCA4 as a lipid transporter that facilitates the removal of potentially toxic retinal compounds from photoreceptors following photoexcitation. An autosomal dominant form of Stargardt disease also known as Stargardt-like dystrophy is caused by mutations in a gene encoding ELOVL4, an enzyme that catalyzes the elongation of very long-chain fatty acids in photoreceptors and other tissues. This review focuses on the molecular characterization of ABCA4 and ELOVL4 and their role in photoreceptor cell biology and the pathogenesis of Stargardt disease.
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Affiliation(s)
- Robert S Molday
- Department of Biochemistry and Molecular Biology, Centre of Macular Research, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, Canada.
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Agbaga MP, Mandal MNA, Anderson RE. Retinal very long-chain PUFAs: new insights from studies on ELOVL4 protein. J Lipid Res 2010; 51:1624-42. [PMID: 20299492 DOI: 10.1194/jlr.r005025] [Citation(s) in RCA: 119] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Compared with other mammalian tissues, retina is highly enriched in PUFA. Long-chain PUFA (LC-PUFA; C18-C24) are essential FAs that are enriched in the retina and are necessary for maintenance of normal retinal development and function. The retina, brain, and sperm also contain very LC-PUFA (VLC-PUFA; >C24). Although VLC-PUFA were discovered more than two decades ago, very little is known about their biosynthesis and functional roles in the retina. This is due mainly to intrinsic difficulties associated with working on these unusually long polyunsaturated hydrocarbon chains and their existence in small amounts. Recent studies on the FA elongase elongation of very long chain fatty acids-4 (ELOVL4) protein, however, suggest that VLC-PUFA probably play some uniquely important roles in the retina as well as the other tissues. Mutations in the ELOVL4 gene are found in patients with autosomal dominant Stargardt disease. Here, we review the recent literature on VLC-PUFA with special emphasis on the elongases responsible for their synthesis. We focus on a novel elongase, ELOVL4, involved in the synthesis of VLC-PUFA, and the importance of these FAs in maintaining the structural and functional integrity of retinal photoreceptors.
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Affiliation(s)
- Martin-Paul Agbaga
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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Ramkumar HL, Zhang J, Chan CC. Retinal ultrastructure of murine models of dry age-related macular degeneration (AMD). Prog Retin Eye Res 2010; 29:169-90. [PMID: 20206286 DOI: 10.1016/j.preteyeres.2010.02.002] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Age-related macular degeneration (AMD) is the most prevalent form of irreversible blindness worldwide in the elderly population. The pathology of dry AMD consists of macular degeneration of photoreceptors and the RPE, lipofuscin (A2E) accumulation, and drusen formation. Mice have been widely used for generating models that simulate human AMD features for investigating the pathogenesis, treatment and prevention of the disease. Although the mouse has no macula, focal atrophy of photoreceptors and RPE, lipofuscin accumulation, and increased A2E can develop in aged mouse eyes. However, drusen are rarely seen in mice because of their simpler Bruch's membrane and different process of lipofuscin extrusion compared with humans. Thus, analyzing basal deposits at the ultrastructural level and understanding the ultrastructural pathologic differences between various mouse AMD models are critical to comprehending the significance of research findings and response to possible therapeutic options for dry AMD. Based on the multifactorial pathogenesis of AMD, murine dry AMD models can be classified into three groups. First, genetically engineered mice that target genes related to juvenile macular dystrophies are the most common models, and they include abcr(-/-) (Stargardt disease), transgenic ELOVL4 (Stargardt-3 dominant inheritary disease), Efemp1(R345W/R345W) (Doyne honeycomb retinal dystrophy), and Timp3(S156C/S156C) (Sorsby fundus dystrophy) mice. Other murine models target genes relevant to AMD, including inflammatory genes such as Cfh(-/-), Ccl2(-/-), Ccr2(-/-), Cx3cr1(-/-), and Ccl2(-/-)/cx3cr1(-/-), oxidative stress associated genes such as Sod1(-/-) and Sod2 knockdown, metabolic pathway genes such as neprilysin(-/-) (amyloid beta), transgenic mcd/mcd (cathepsin D), Cp(-/-)/Heph(-/Y) (ferroxidase ceruloplasmin/hepaestin, iron metabolism), and transgenic ApoE4 on high fat and high cholesterol diet (lipid metabolism). Second, mice have also been immunologically manipulated by immunization with carboxyethylpyrrole (CEP), an oxidative fragment of DHA found in drusen, and found to present with dry AMD features. Third, natural mouse strains such as arrd2/arrd2 (Mdm gene mutation) and the senescence accelerated mice (SAM) spontaneously develop features of dry AMD like photoreceptor atrophy and thickening of Bruch's membrane. All the aforementioned models develop retinal lesions with various features that simulate dry AMD lesions: focal photoreceptor degeneration, abnormal RPE with increased lipofuscin, basal infolding, decreased melanosomes and degeneration. However, Bruch's membrane changes are less common. Most mice develop retinal lesions at an older age (6-24 months, depending on the models), while the Ccl2(-/-)/cx3cr1(-/-) mice develop lesions by 4-6 weeks. Although murine models present various degrees of retinal and/or RPE degeneration, classical drusen is extremely rare. Using electron microscopy, small drusenoid deposits are found between RPE and Bruch's membrane in a few models including Efemp1(R345W/R345W), Ccl2(-/-)/cx3cr1(-/-), neprilysin(-/-), transgenic mcd/mcd, and ApoE4 transgenic mice on a high fat diet. High A2E levels are measured in the retinas of abcr(-/-), transgenic ELOVL4, and Ccl2(-/-)/cx3cr1(-/-) mice. In summary, murine models provide useful tools for studying AMD pathogenesis and evaluating novel therapies for this disease. This review compares the major dry AMD murine models and discusses retinal pathology at the ultrastructural level.
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Affiliation(s)
- Hema L Ramkumar
- Immunopathology Section, Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, MD 20892-1857, USA
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Abstract
Stargardt-like macular degeneration (STGD3) is an early onset, autosomal dominant macular degeneration. STGD3 is characterized by a progressive pathology, the loss of central vision, atrophy of the retinal pigment epithelium, and accumulation of lipofuscin, clinical features that are also characteristic of age-related macular degeneration. The onset of clinical symptoms in STGD3, however, is typically observed within the second or third decade of life (i.e., starting in the teenage years). The clinical profile at any given age among STGD3 patients can be variable suggesting that, although STGD3 is a single gene defect, other genetic or environmental factors may play a role in moderating the final disease phenotype. Genetic studies localized the STGD3 disease locus to a small region on the short arm of human chromosome 6, and application of a positional candidate gene approach identified protein truncating mutations in the elongation of very long chain fatty acids-4 gene (ELOVL4) in patients with this disease. The ELOVL4 gene encodes a protein homologous to the ELO group of proteins that participate in fatty acid elongation in yeast. Pathogenic mutations found in the ELOVL4 gene result in altered trafficking of the protein and behave with a dominant negative effect. Mice carrying an Elovl4 mutation developed photoreceptor degeneration and depletion of very long chain fatty acids (VLCFA). ELOVL4 protein participates in the synthesis of fatty acids with chain length longer than 26 carbons. Studies on ELOVL4 indicate that VLCFA may be necessary for normal function of the retina, and the defective protein trafficking and/or altered VLCFA elongation underlies the pathology associated with STGD3. Determining the role of VLCFA in the retina and discerning the implications of abnormal trafficking of mutant ELOVL4 and depleted VLCFA content in the pathology of STGD3 will provide valuable insight in understanding the retinal structure, function, and pathology underlying STGD3 and may lead to a better understanding of the process of macular disease in general.
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Role of Stargardt-3 macular dystrophy protein (ELOVL4) in the biosynthesis of very long chain fatty acids. Proc Natl Acad Sci U S A 2008; 105:12843-8. [PMID: 18728184 DOI: 10.1073/pnas.0802607105] [Citation(s) in RCA: 196] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Stargardt-like macular dystrophy (STGD3) is a dominantly inherited juvenile macular degeneration that eventually leads to loss of vision. Three independent mutations causing STGD3 have been identified in exon six of a gene named Elongation of very long chain fatty acids 4 (ELOVL4). The ELOVL4 protein was predicted to be involved in fatty acid elongation, although evidence for this and the specific step(s) it may catalyze have remained elusive. Here, using a gain-of-function approach, we provide direct and compelling evidence that ELOVL4 is required for the synthesis of C28 and C30 saturated fatty acids (VLC-FA) and of C28-C38 very long chain polyunsaturated fatty acids (VLC-PUFA), the latter being uniquely expressed in retina, sperm, and brain. Rat neonatal cardiomyocytes and a human retinal epithelium cell line (ARPE-19) were transduced with recombinant adenovirus type 5 carrying mouse Elovl4 and supplemented with 24:0, 20:5n3, or 22:5n3. The 24:0 was elongated to 28:0 and 30:0; 20:5n3 and 22:5n3 were elongated to a series of C28-C38 PUFA. Because retinal degeneration is the only known phenotype in STGD3 disease, we propose that reduced VLC-PUFA in the retinas of these patients may be the cause of photoreceptor cell death.
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Vasireddy V, Sharon M, Salem N, Ayyagari R. Role of ELOVL4 in fatty acid metabolism. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 613:283-90. [PMID: 18188956 DOI: 10.1007/978-0-387-74904-4_33] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Vidyullatha Vasireddy
- Ophthalmology and Visual Sciences, W. K. Kellogg Eye Center, University of Michigan, Ann Arbor, USA.
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A Stargardt disease-3 mutation in the mouse Elovl4 gene causes retinal deficiency of C32-C36 acyl phosphatidylcholines. FEBS Lett 2007; 581:5459-63. [PMID: 17983602 DOI: 10.1016/j.febslet.2007.10.050] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2007] [Revised: 10/25/2007] [Accepted: 10/26/2007] [Indexed: 11/22/2022]
Abstract
Stargardt disease-3 (STGD3) is a juvenile dominant macular degeneration caused by mutations in elongase of very long chain fatty acid-4. All identified mutations produce a truncated protein which lacks a motif for protein retention in endoplasmic reticulum, the site of fatty acid synthesis. In these studies of Stgd3-knockin mice carrying a human pathogenic mutation, we examined two potential pathogenic mechanisms: truncated protein-induced cellular stress and lipid product deficiency. Analysis of mutant retinas detected no cellular stress but demonstrated selective deficiency of C32-C36 acyl phosphatidylcholines. We conclude that this deficit leads to the human STGD3 pathology.
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31
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Marmorstein AD, Marmorstein LY. The challenge of modeling macular degeneration in mice. Trends Genet 2007; 23:225-31. [PMID: 17368622 DOI: 10.1016/j.tig.2007.03.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2006] [Revised: 01/08/2007] [Accepted: 03/01/2007] [Indexed: 01/17/2023]
Abstract
Macular degenerations (MD), age-related or inherited, interfere with the ability to read, drive and recognize faces. Understanding this class of diseases has been challenging because the mouse, the mammal most amenable to genetic manipulation, lacks a macula. Here we discuss whether we can model MD in the mouse, present criteria for an 'ideal' mouse model of MD and discuss how mouse models have contributed to our knowledge of MD by contrasting how well they meet the 'ideal' criteria with how informative they have actually been. By modeling MD in mice, we can learn about aspects of MD that an animal with a macula would be unable to teach us.
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Affiliation(s)
- Alan D Marmorstein
- Department of Ophthalmology and Vision Science, University of Arizona, 655 North Alvernon Way, Suite 108, Tucson, AZ 85711, USA.
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McMahon A, Butovich IA, Mata NL, Klein M, Ritter R, Richardson J, Birch DG, Edwards AO, Kedzierski W. Retinal pathology and skin barrier defect in mice carrying a Stargardt disease-3 mutation in elongase of very long chain fatty acids-4. Mol Vis 2007; 13:258-72. [PMID: 17356513 PMCID: PMC2633486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
PURPOSE Autosomal dominant Stargardt disease-3 (STGD3) is caused by mutations in elongase of very long chain fatty acids-4 (ELOVL4). The goal of this study was to generate and characterize heterozygous and homozygous knockin-mice that carry a human STGD3 pathogenic mutation in the mouse Elovl4 gene. METHODS Recombinant Stgd3-knockin mice were generated using a DNA construct which introduced a pathogenic five-base pair deletion and two point mutations in exon 6 of the Elovl4 gene. Stgd3-mouse genotypes were confirmed by Southern blot analysis and expression of wild-type (wt) and mutated Elovl4 mRNAs assayed by nuclease protection assay. The retinal phenotype of heterozygous Stgd3 mice was characterized by morphological studies, elecroretinographic (ERG) analysis and assay of lipofuscin accumulation. Homozygous Stgd3 mice were examined for both retinal and gross morphology. They were also analyzed for skin morphology and skin barrier function, and for epidermal lipid content using high performance liquid chromatography (HPLC) combined with mass spectrometry (MS). RESULTS The Stgd3 allele codes for a truncated mouse Elovl4 protein, which also contains the same aberrant 8-amino acid C-terminus encoded by the human pathogenic STGD3 allele. Heterozygous Stgd3 mice expressed equal amounts of both wt and mutant Elovl4 mRNAs in the retina, showed no significant changes in retinal morphology, but did show accumulation of lipofuscin and reduced visual function. Homozygous Stgd3 mice were born with an expected Mendelian frequency, without any initial gross anatomical or behavioral abnormalities. By 6-12 h postpartum, they became dehydrated and died. A skin permeability assay detected a defect in epidermal barrier function. Homozygous mutant epidermis expressed a normal content of mutated Elovl4 mRNA and contained all four epidermal cellular layers. HPLC/MS analysis of epidermal lipids revealed the presence of all barrier lipids with the exception of the complete absence of acylceramides, the critical lipids for barrier function of the skin. CONCLUSIONS The generated Stgd3-knockin mice are a genetic model of human STGD3 and reproduce features of the human disease: accumulation of lipofuscin and reduced visual functions. Homozygous Stgd3 mice showed a complete absence of acylceramides from the epidermis. Their absence suggests a role for Elovl4 in acylceramide synthesis, and in particular, a role in the synthesis of the unique very long chain C30-C40 fatty acids present in skin acylceramides.
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Affiliation(s)
- Anne McMahon
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Igor A. Butovich
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX
| | | | | | - Robert Ritter
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX
| | - James Richardson
- Department of Pathology and Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX
| | - David G. Birch
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX
- Retina Foundation of the Southwest, Dallas, TX
| | - Albert O. Edwards
- McDermott Center for Human Growth and Development, The University of Texas Southwestern Medical Center, Dallas, TX
- Institute for Retina Research, Dallas, Texas
| | - Wojciech Kedzierski
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX
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Cameron DJ, Tong Z, Yang Z, Kaminoh J, Kamiyah S, Chen H, Zeng J, Chen Y, Luo L, Zhang K. Essential role of Elovl4 in very long chain fatty acid synthesis, skin permeability barrier function, and neonatal survival. Int J Biol Sci 2007; 3:111-9. [PMID: 17304340 PMCID: PMC1796949 DOI: 10.7150/ijbs.3.111] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2007] [Accepted: 02/06/2007] [Indexed: 11/05/2022] Open
Abstract
Mutations in the gene ELOVL4 have been shown to cause stargardt-like macular dystrophy. ELOVL4 is part of a family of fatty acid elongases and is yet to have a specific elongase activity assigned to it. We generated Elovl4 Y270X mutant mice and characterized the homozygous mutant as well as homozygous Elovl4 knockout mice in order to better understand the function or role of Elovl4. We found that mice lacking a functional Elovl4 protein died perinatally. The cause of death appears to be from dehydration due to faulty permeability barrier formation in the skin. Further biochemical analysis revealed a significant reduction in free fatty acids longer than C26 in homozygous mutant and knockout mouse skin. These results implicate the importance of these long chain fatty acids in skin barrier development. Furthermore, we suggest that Elovl4 is likely involved in the elongation of C26 and longer fatty acids.
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Affiliation(s)
- D. Joshua Cameron
- 1. Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
- 2. Program in Human Molecular Biology & Genetics, Eccles Institute of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Zongzhong Tong
- 1. Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
- 2. Program in Human Molecular Biology & Genetics, Eccles Institute of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Zhenglin Yang
- 1. Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
- 2. Program in Human Molecular Biology & Genetics, Eccles Institute of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Jack Kaminoh
- 1. Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
- 2. Program in Human Molecular Biology & Genetics, Eccles Institute of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Shin Kamiyah
- 1. Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
- 2. Program in Human Molecular Biology & Genetics, Eccles Institute of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Haoyu Chen
- 1. Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
- 2. Program in Human Molecular Biology & Genetics, Eccles Institute of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Jiexi Zeng
- 1. Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
- 2. Program in Human Molecular Biology & Genetics, Eccles Institute of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Yali Chen
- 1. Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
- 2. Program in Human Molecular Biology & Genetics, Eccles Institute of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Ling Luo
- 1. Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
- 2. Program in Human Molecular Biology & Genetics, Eccles Institute of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Kang Zhang
- 1. Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
- 2. Program in Human Molecular Biology & Genetics, Eccles Institute of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
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Vasireddy V, Uchida Y, Salem N, Kim SY, Mandal MNA, Reddy GB, Bodepudi R, Alderson NL, Brown JC, Hama H, Dlugosz A, Elias PM, Holleran WM, Ayyagari R. Loss of functional ELOVL4 depletes very long-chain fatty acids (> or =C28) and the unique omega-O-acylceramides in skin leading to neonatal death. Hum Mol Genet 2007; 16:471-82. [PMID: 17208947 PMCID: PMC1839956 DOI: 10.1093/hmg/ddl480] [Citation(s) in RCA: 197] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mutations in elongation of very long-chain fatty acid-4 (ELOVL4) are associated with autosomal dominant Stargardt-like macular degeneration (STGD3), with a five base-pair (5 bp) deletion mutation resulting in the loss of 51 carboxy-terminal amino acids and truncation of the protein. In addition to the retina, Elovl4 is expressed in a limited number of mammalian tissues, including skin, with unknown function(s). We generated a knock-in mouse model with the 5-bp deletion in the Elovl4 gene. As anticipated, mice carrying this mutation in the heterozygous state (Elovl4(+/del)) exhibit progressive photoreceptor degeneration. Unexpectedly, homozygous mice (Elovl4(del/del)) display scaly, wrinkled skin, have severely compromised epidermal permeability barrier function, and die within a few hours after birth. Histopathological evaluation of the Elovl4(del/del) pups revealed no apparent abnormality(ies) in vital internal organs. However, skin histology showed an abnormally-compacted outer epidermis [stratum corneum (SC)], while electron microscopy revealed deficient epidermal lamellar body contents, and lack of normal SC lamellar membranes that are essential for permeability barrier function. Lipid analyses of epidermis from Elovl4(del/del) mice revealed a global decrease in very long-chain fatty acids (VLFAs) (i.e., carbon chain > or =C28) in both the ceramide/glucosylceramide and the free fatty-acid fractions. Strikingly, Elovl4(del/del) skin was devoid of the epidermal-unique omega-O-acylceramides, that are key hydrophobic components of the extracellular lamellar membranes in mammalian SC. These findings demonstrate that ELOVL4 is required for generating VLFA critical for epidermal barrier function, and that the lack of epidermal omega-O-acylceramides is incompatible with survival in a desiccating environment.
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Affiliation(s)
- Vidyullatha Vasireddy
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI- 48105
| | - Yoshikazu Uchida
- Department of Dermatology, School of Medicine, University of California San Francisco, and Veterans Administration Medical Center, San Francisco, CA-94121
| | - Norman Salem
- Laboratory of Membrane Biochemistry and Biophysics, NIAAA, National Institutes of Health, Rockville, MD-20892
| | - Soo Yeon Kim
- Laboratory of Membrane Biochemistry and Biophysics, NIAAA, National Institutes of Health, Rockville, MD-20892
| | - Md Nawajesh Ali Mandal
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI- 48105
| | | | - Ravi Bodepudi
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI- 48105
| | - Nathan L. Alderson
- Department of Medicine Medical University of South Carolina, Charleston, SC-29425
| | | | - Hiroko Hama
- Department of Medicine Medical University of South Carolina, Charleston, SC-29425
| | - Andrzej Dlugosz
- Department of Dermatology, University of Michigan, Ann Arbor, MI- 48105
| | - Peter M. Elias
- Department of Dermatology, School of Medicine, University of California San Francisco, and Veterans Administration Medical Center, San Francisco, CA-94121
| | - Walter M. Holleran
- Department of Dermatology, School of Medicine, University of California San Francisco, and Veterans Administration Medical Center, San Francisco, CA-94121
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of California, San Francisco, CA-94143
| | - Radha Ayyagari
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI- 48105
- Address for correspondence: *Radha Ayyagari, PhD., Department of Ophthalmology and Visual Sciences, W.K. Kellogg Eye Center, 1000 Wall Street, Ann Arbor, MI 48105, Phone: 734-647-6345, Fax: 734-936-7231,
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