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Wei L, Weng S, Lu X, Zhu S, Yang Q, Chen YQ. 3-Hydroxyacyl-CoA dehydratase 2 deficiency confers resistance to diet-induced obesity and glucose intolerance. Biochem Biophys Res Commun 2022; 605:134-140. [PMID: 35325655 DOI: 10.1016/j.bbrc.2022.03.057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 03/10/2022] [Indexed: 11/02/2022]
Abstract
Obesity and associated complications are becoming a pandemic. Inhibiting fatty acid synthesis and elongation is an important intervention for the treatment of obesity. Despite intensive investigations, many potential therapeutic targets have yet to be discovered. In this study, decreased expression of Hacd2 (a newly found enzyme in fatty acid elongation) was found in HFD induced mice and loss of Hacd2 expression in the liver protected mice against HFD induced obesity as well as associated fatty liver disease and diabetes. Additionally, further study indicated that hepatic HACD2 deficiency increased energy expenditure by upregulating the transcription of thermogenic programming genes. Our results suggest that HACD2 may be a promising therapeutic target for the management of obesity and associated metabolic diseases.
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Affiliation(s)
- Lengyun Wei
- Wuxi School of Medicine, Jiangnan University, Jiangsu Province, 214122, China; Wuxi Translational Medicine Research Center and Jiangsu Translational Medicine Research Institute Wuxi Branch, China; School of Food Science and Technology, Jiangnan University, Jiangsu Province, 214122, China
| | - Shengmei Weng
- Wuxi School of Medicine, Jiangnan University, Jiangsu Province, 214122, China; Wuxi Translational Medicine Research Center and Jiangsu Translational Medicine Research Institute Wuxi Branch, China
| | - Xuyang Lu
- Wuxi School of Medicine, Jiangnan University, Jiangsu Province, 214122, China; Wuxi Translational Medicine Research Center and Jiangsu Translational Medicine Research Institute Wuxi Branch, China; School of Food Science and Technology, Jiangnan University, Jiangsu Province, 214122, China
| | - Shenglong Zhu
- Wuxi School of Medicine, Jiangnan University, Jiangsu Province, 214122, China; Wuxi Translational Medicine Research Center and Jiangsu Translational Medicine Research Institute Wuxi Branch, China
| | - Qin Yang
- Wuxi School of Medicine, Jiangnan University, Jiangsu Province, 214122, China; Wuxi Translational Medicine Research Center and Jiangsu Translational Medicine Research Institute Wuxi Branch, China
| | - Yong Q Chen
- Wuxi School of Medicine, Jiangnan University, Jiangsu Province, 214122, China; Wuxi Translational Medicine Research Center and Jiangsu Translational Medicine Research Institute Wuxi Branch, China; School of Food Science and Technology, Jiangnan University, Jiangsu Province, 214122, China.
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2
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Lewandowski D, Sander CL, Tworak A, Gao F, Xu Q, Skowronska-Krawczyk D. Dynamic lipid turnover in photoreceptors and retinal pigment epithelium throughout life. Prog Retin Eye Res 2021; 89:101037. [PMID: 34971765 PMCID: PMC10361839 DOI: 10.1016/j.preteyeres.2021.101037] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 12/13/2021] [Accepted: 12/15/2021] [Indexed: 12/13/2022]
Abstract
The retinal pigment epithelium-photoreceptor interphase is renewed each day in a stunning display of cellular interdependence. While photoreceptors use photosensitive pigments to convert light into electrical signals, the RPE supports photoreceptors in their function by phagocytizing shed photoreceptor tips, regulating the blood retina barrier, and modulating inflammatory responses, as well as regenerating the 11-cis-retinal chromophore via the classical visual cycle. These processes involve multiple protein complexes, tightly regulated ligand-receptors interactions, and a plethora of lipids and protein-lipids interactions. The role of lipids in maintaining a healthy interplay between the RPE and photoreceptors has not been fully delineated. In recent years, novel technologies have resulted in major advancements in understanding several facets of this interplay, including the involvement of lipids in phagocytosis and phagolysosome function, nutrient recycling, and the metabolic dependence between the two cell types. In this review, we aim to integrate the complex role of lipids in photoreceptor and RPE function, emphasizing the dynamic exchange between the cells as well as discuss how these processes are affected in aging and retinal diseases.
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Affiliation(s)
- Dominik Lewandowski
- Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA
| | - Christopher L Sander
- Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA; Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Aleksander Tworak
- Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA
| | - Fangyuan Gao
- Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA
| | - Qianlan Xu
- Department of Physiology and Biophysics, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA; Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA
| | - Dorota Skowronska-Krawczyk
- Department of Physiology and Biophysics, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA; Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, UC Irvine, Irvine, CA, USA.
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3
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Landowski M, Bowes Rickman C. Targeting Lipid Metabolism for the Treatment of Age-Related Macular Degeneration: Insights from Preclinical Mouse Models. J Ocul Pharmacol Ther 2021; 38:3-32. [PMID: 34788573 PMCID: PMC8817708 DOI: 10.1089/jop.2021.0067] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Age-related macular degeneration (AMD) is a major leading cause of irreversible visual impairment in the world with limited therapeutic interventions. Histological, biochemical, genetic, and epidemiological studies strongly implicate dysregulated lipid metabolism in the retinal pigmented epithelium (RPE) in AMD pathobiology. However, effective therapies targeting lipid metabolism still need to be identified and developed for this blinding disease. To test lipid metabolism-targeting therapies, preclinical AMD mouse models are needed to establish therapeutic efficacy and the role of lipid metabolism in the development of AMD-like pathology. In this review, we provide a comprehensive overview of current AMD mouse models available to researchers that could be used to provide preclinical evidence supporting therapies targeting lipid metabolism for AMD. Based on previous studies of AMD mouse models, we discuss strategies to modulate lipid metabolism as well as examples of studies evaluating lipid-targeting therapeutics to restore lipid processing in the RPE. The use of AMD mouse models may lead to worthy lipid-targeting candidate therapies for clinical trials to prevent the blindness caused by AMD.
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Affiliation(s)
- Michael Landowski
- Department of Medical Genetics, University of Wisconsin-Madison, Madison, Wisconsin, USA.,McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, Wisconsin, USA.,Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Catherine Bowes Rickman
- Department of Ophthalmology, Duke University Medical Center, Durham, North Carolina, USA.,Department of Cell Biology, Duke University Medical Center, Durham, North Carolina, USA
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4
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Nagaraja RY, Sherry DM, Fessler JL, Stiles MA, Li F, Multani K, Orock A, Ahmad M, Brush RS, Anderson RE, Agbaga MP, Deák F. W246G Mutant ELOVL4 Impairs Synaptic Plasticity in Parallel and Climbing Fibers and Causes Motor Defects in a Rat Model of SCA34. Mol Neurobiol 2021; 58:4921-4943. [PMID: 34227061 PMCID: PMC8497303 DOI: 10.1007/s12035-021-02439-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 05/25/2021] [Indexed: 12/14/2022]
Abstract
Spinocerebellar ataxia (SCA) is a neurodegenerative disorder characterized by ataxia and cerebellar atrophy. A number of different mutations gives rise to different types of SCA with characteristic ages of onset, symptomatology, and rates of progression. SCA type 34 (SCA34) is caused by mutations in ELOVL4 (ELOngation of Very Long-chain fatty acids 4), a fatty acid elongase essential for biosynthesis of Very Long Chain Saturated and Polyunsaturated Fatty Acids (VLC-SFA and VLC-PUFA, resp., ≥28 carbons), which have important functions in the brain, skin, retina, Meibomian glands, testes, and sperm. We generated a rat model of SCA34 by knock-in of the SCA34-causing 736T>G (p.W246G) ELOVL4 mutation. Rats carrying the mutation developed impaired motor deficits by 2 months of age. To understand the mechanism of these motor deficits, we performed electrophysiological studies using cerebellar slices from rats homozygous for W246G mutant ELOVL4 and found marked reduction of long-term potentiation at parallel fiber synapses and long-term depression at climbing fiber synapses onto Purkinje cells. Neuroanatomical analysis of the cerebellum showed normal cytoarchitectural organization with no evidence of degeneration out to 6 months of age. These results point to ELOVL4 as essential for motor function and cerebellar synaptic plasticity. The results further suggest that ataxia in SCA34 patients may arise from a primary impairment of synaptic plasticity and cerebellar network desynchronization before onset of neurodegeneration and progression of the disease at a later age.
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Affiliation(s)
- Raghavendra Y Nagaraja
- Biochemistry & Molecular Biology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA.,Neuroscience Program, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA.,Cell Biology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA
| | - David M Sherry
- Neuroscience Program, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA.,Cell Biology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA.,Pharmaceutical Sciences, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA
| | - Jennifer L Fessler
- Cell Biology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA
| | - Megan A Stiles
- Ophthalmology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA.,Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA
| | - Feng Li
- Ophthalmology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA.,Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA
| | - Karanpreet Multani
- Ophthalmology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA.,Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA
| | - Albert Orock
- Neuroscience Program, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA.,Reynolds Center on Aging, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA
| | - Mohiuddin Ahmad
- Neuroscience Program, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA.,Cell Biology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA
| | - Richard S Brush
- Ophthalmology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA.,Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA
| | - Robert E Anderson
- Neuroscience Program, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA.,Cell Biology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA.,Ophthalmology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA.,Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA
| | - Martin-Paul Agbaga
- Neuroscience Program, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA. .,Cell Biology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA. .,Ophthalmology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA. .,Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA. .,Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA.
| | - Ferenc Deák
- Biochemistry & Molecular Biology, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA. .,Neuroscience Program, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA. .,Reynolds Center on Aging, University of Oklahoma Health Sciences Center, 608 Stanton L. Young Blvd, DMEI 428PP, Oklahoma City, OK, 73104, USA. .,Dept. of Neuroscience & Regenerative Medicine, Medical College of Georgia, 1120 15th Str, CA4010, Augusta, GA, 30912, USA.
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5
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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] [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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6
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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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7
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Defective phagosome motility and degradation in cell nonautonomous RPE pathogenesis of a dominant macular degeneration. Proc Natl Acad Sci U S A 2018; 115:5468-5473. [PMID: 29735674 DOI: 10.1073/pnas.1709211115] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Stargardt macular dystrophy 3 (STGD3) is caused by dominant mutations in the ELOVL4 gene. Like other macular degenerations, pathogenesis within the retinal pigment epithelium (RPE) appears to contribute to the loss of photoreceptors from the central retina. However, the RPE does not express ELOVL4, suggesting photoreceptor cell loss in STGD3 occurs through two cell nonautonomous events: mutant photoreceptors first affect RPE cell pathogenesis, and then, second, RPE dysfunction leads to photoreceptor cell death. Here, we have investigated how the RPE pathology occurs, using a STGD3 mouse model in which mutant human ELOVL4 is expressed in the photoreceptors. We found that the mutant protein was aberrantly localized to the photoreceptor outer segment (POS), and that resulting POS phagosomes were degraded more slowly in the RPE. In cell culture, the mutant POSs are ingested by primary RPE cells normally, but the phagosomes are processed inefficiently, even by wild-type RPE. The mutant phagosomes excessively sequester RAB7A and dynein, and have impaired motility. We propose that the abnormal presence of ELOVL4 protein in POSs results in phagosomes that are defective in recruiting appropriate motor protein linkers, thus contributing to slower degradation because their altered motility results in slower basal migration and fewer productive encounters with endolysosomes. In the transgenic mouse retinas, the RPE accumulated abnormal-looking phagosomes and oxidative stress adducts; these pathological changes were followed by pathology in the neural retina. Our results indicate inefficient phagosome degradation as a key component of the first cell nonautonomous event underlying retinal degeneration due to mutant ELOVL4.
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Neuroprotective Strategy in Retinal Degeneration: Suppressing ER Stress-Induced Cell Death via Inhibition of the mTOR Signal. Int J Mol Sci 2017; 18:ijms18010201. [PMID: 28106827 PMCID: PMC5297831 DOI: 10.3390/ijms18010201] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 01/13/2017] [Accepted: 01/16/2017] [Indexed: 12/11/2022] Open
Abstract
The retina is a specialized sensory organ, which is essential for light detection and visual formation in the human eye. Inherited retinal degenerations are a heterogeneous group of eye diseases that can eventually cause permanent vision loss. UPR (unfolded protein response) and ER (endoplasmic reticulum) stress plays an important role in the pathological mechanism of retinal degenerative diseases. mTOR (the mammalian target of rapamycin) kinase, as a signaling hub, controls many cellular processes, covering protein synthesis, RNA translation, ER stress, and apoptosis. Here, the hypothesis that inhibition of mTOR signaling suppresses ER stress-induced cell death in retinal degenerative disorders is discussed. This review surveys knowledge of the influence of mTOR signaling on ER stress arising from misfolded proteins and genetic mutations in retinal degenerative diseases and highlights potential neuroprotective strategies for treatment and therapeutic implications.
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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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