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Cheng ML, Yang CH, Wu PT, Li YC, Sun HW, Lin G, Ho HY. Malonyl-CoA Accumulation as a Compensatory Cytoprotective Mechanism in Cardiac Cells in Response to 7-Ketocholesterol-Induced Growth Retardation. Int J Mol Sci 2023; 24:ijms24054418. [PMID: 36901848 PMCID: PMC10002498 DOI: 10.3390/ijms24054418] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 02/20/2023] [Accepted: 02/21/2023] [Indexed: 02/25/2023] Open
Abstract
The major oxidized product of cholesterol, 7-Ketocholesterol (7KCh), causes cellular oxidative damage. In the present study, we investigated the physiological responses of cardiomyocytes to 7KCh. A 7KCh treatment inhibited the growth of cardiac cells and their mitochondrial oxygen consumption. It was accompanied by a compensatory increase in mitochondrial mass and adaptive metabolic remodeling. The application of [U-13C] glucose labeling revealed an increased production of malonyl-CoA but a decreased formation of hydroxymethylglutaryl-coenzyme A (HMG-CoA) in the 7KCh-treated cells. The flux of the tricarboxylic acid (TCA) cycle decreased, while that of anaplerotic reaction increased, suggesting a net conversion of pyruvate to malonyl-CoA. The accumulation of malonyl-CoA inhibited the carnitine palmitoyltransferase-1 (CPT-1) activity, probably accounting for the 7-KCh-induced suppression of β-oxidation. We further examined the physiological roles of malonyl-CoA accumulation. Treatment with the inhibitor of malonyl-CoA decarboxylase, which increased the intracellular malonyl-CoA level, mitigated the growth inhibitory effect of 7KCh, whereas the treatment with the inhibitor of acetyl-CoA carboxylase, which reduced malonyl-CoA content, aggravated such a growth inhibitory effect. Knockout of malonyl-CoA decarboxylase gene (Mlycd-/-) alleviated the growth inhibitory effect of 7KCh. It was accompanied by improvement of the mitochondrial functions. These findings suggest that the formation of malonyl-CoA may represent a compensatory cytoprotective mechanism to sustain the growth of 7KCh-treated cells.
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Affiliation(s)
- Mei-Ling Cheng
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan City 33302, Taiwan
- Healthy Aging Research Center, Chang Gung University, Taoyuan City 33302, Taiwan
- Metabolomics Core Laboratory, Healthy Aging Research Center, Chang Gung University, Taoyuan City 33302, Taiwan
- Clinical Metabolomics Core Laboratory, Chang Gung Memorial Hospital at Linkou, Taoyuan City 33302, Taiwan
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan City 33302, Taiwan
| | - Cheng-Hung Yang
- Healthy Aging Research Center, Chang Gung University, Taoyuan City 33302, Taiwan
- Metabolomics Core Laboratory, Healthy Aging Research Center, Chang Gung University, Taoyuan City 33302, Taiwan
| | - Pei-Ting Wu
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan City 33302, Taiwan
| | - Yi-Chin Li
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan City 33302, Taiwan
| | - Hao-Wei Sun
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan City 33302, Taiwan
| | - Gigin Lin
- Clinical Metabolomics Core Laboratory, Chang Gung Memorial Hospital at Linkou, Taoyuan City 33302, Taiwan
- Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital at Linkou, Taoyuan City 33302, Taiwan
- Imaging Core Laboratory, Institute for Radiological Research, Chang Gung University, Taoyuan City 33302, Taiwan
- Department of Medical Imaging and Radiological Sciences, Chang Gung University, Taoyuan City 33302, Taiwan
| | - Hung-Yao Ho
- Healthy Aging Research Center, Chang Gung University, Taoyuan City 33302, Taiwan
- Metabolomics Core Laboratory, Healthy Aging Research Center, Chang Gung University, Taoyuan City 33302, Taiwan
- Clinical Metabolomics Core Laboratory, Chang Gung Memorial Hospital at Linkou, Taoyuan City 33302, Taiwan
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan City 33302, Taiwan
- Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan City 33302, Taiwan
- Correspondence: ; Tel.: +886-(3)-2118800 (ext. 3318)
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Aqul AA, Ramirez CM, Lopez AM, Burns DK, Repa JJ, Turley SD. Molecular markers of brain cholesterol homeostasis are unchanged despite a smaller brain mass in a mouse model of cholesteryl ester storage disease. Lipids 2022; 57:3-16. [PMID: 34618372 PMCID: PMC8766890 DOI: 10.1002/lipd.12325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 09/17/2021] [Accepted: 09/20/2021] [Indexed: 01/03/2023]
Abstract
Lysosomal acid lipase (LAL), encoded by the gene LIPA, facilitates the intracellular processing of lipids by hydrolyzing cholesteryl esters and triacylglycerols present in newly internalized lipoproteins. Loss-of-function mutations in LIPA result in cholesteryl ester storage disease (CESD) or Wolman disease when mutations cause complete loss of LAL activity. Although the phenotype of a mouse CESD model has been extensively characterized, there has not been a focus on the brain at different stages of disease progression. In the current studies, whole-brain mass and the concentrations of cholesterol in both the esterified (EC) and unesterified (UC) fractions were measured in Lal-/- and matching Lal+/+ mice (FVB-N strain) at ages ranging from 14 up to 280 days after birth. Compared to Lal+/+ controls at 50, 68-76, 140-142, and 230-280 days of age, Lal-/- mice had brain weights that averaged approximately 6%, 7%, 18%, and 20% less, respectively. Brain EC levels were higher in the Lal-/- mice at every age, being elevated 27-fold at 230-280 days. Brain UC concentrations did not show a genotypic difference at any age. The elevated brain EC levels in the Lal-/- mice did not reflect EC in residual blood. An mRNA expression analysis for an array of genes involved in the synthesis, catabolism, storage, and transport of cholesterol in the brains of 141-day old mice did not detect any genotypic differences although the relative mRNA levels for several markers of inflammation were moderately elevated in the Lal-/- mice. The possible sites of EC accretion in the central nervous system are discussed.
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Affiliation(s)
- Amal A. Aqul
- Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas TX 75390 USA
| | - Charina M. Ramirez
- Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas TX 75390 USA
| | - Adam M. Lopez
- Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas TX 75390 USA
| | - Dennis K. Burns
- Department of Pathology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas TX 75390 USA
| | - Joyce J. Repa
- Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas TX 75390 USA
- Department of Physiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas TX 75390 USA
| | - Stephen D. Turley
- Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas TX 75390 USA
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7-Ketocholesterol Induces Lipid Metabolic Reprogramming and Enhances Cholesterol Ester Accumulation in Cardiac Cells. Cells 2021; 10:cells10123597. [PMID: 34944104 PMCID: PMC8700522 DOI: 10.3390/cells10123597] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Revised: 12/12/2021] [Accepted: 12/17/2021] [Indexed: 12/28/2022] Open
Abstract
7-Ketocholesterol (7KCh) is a major oxidized cholesterol product abundant in lipoprotein deposits and atherosclerotic plaques. Our previous study has shown that 7KCh accumulates in erythrocytes of heart failure patients, and further investigation centered on how 7KCh may affect metabolism in cardiomyocytes. We applied metabolomics to study the metabolic changes in cardiac cell line HL-1 after treatment with 7KCh. Mevalonic acid (MVA) pathway-derived metabolites, such as farnesyl-pyrophosphate and geranylgeranyl-pyrophosphate, phospholipids, and triacylglycerols levels significantly declined, while the levels of lysophospholipids, such as lysophosphatidylcholines (lysoPCs) and lysophosphatidylethanolamines (lysoPEs), considerably increased in 7KCh-treated cells. Furthermore, the cholesterol content showed no significant change, but the production of cholesteryl esters was enhanced in the treated cells. To explore the possible mechanisms, we applied mRNA-sequencing (mRNA-seq) to study genes differentially expressed in 7KCh-treated cells. The transcriptomic analysis revealed that genes involved in lipid metabolic processes, including MVA biosynthesis and cholesterol transport and esterification, were differentially expressed in treated cells. Integrated analysis of both metabolomic and transcriptomic data suggests that 7KCh induces cholesteryl ester accumulation and reprogramming of lipid metabolism through altered transcription of such genes as sterol O-acyltransferase- and phospholipase A2-encoding genes. The 7KCh-induced reprogramming of lipid metabolism in cardiac cells may be implicated in the pathogenesis of cardiovascular diseases.
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Ghzaiel I, Sassi K, Zarrouk A, Nury T, Ksila M, Leoni V, Bouhaouala-Zahar B, Hammami S, Hammami M, Mackrill JJ, Samadi M, Ghrairi T, Vejux A, Lizard G. 7-Ketocholesterol: Effects on viral infections and hypothetical contribution in COVID-19. J Steroid Biochem Mol Biol 2021; 212:105939. [PMID: 34118414 PMCID: PMC8188774 DOI: 10.1016/j.jsbmb.2021.105939] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 06/04/2021] [Accepted: 06/07/2021] [Indexed: 02/06/2023]
Abstract
7-Ketocholesterol, which is one of the earliest cholesterol oxidization products identified, is essentially formed by the auto-oxidation of cholesterol. In the body, 7-ketocholesterol is both provided by food and produced endogenously. This pro-oxidant and pro-inflammatory molecule, which can activate apoptosis and autophagy at high concentrations, is an abundant component of oxidized Low Density Lipoproteins. 7-Ketocholesterol appears to significantly contribute to the development of age-related diseases (cardiovascular diseases, age-related macular degeneration, and Alzheimer's disease), chronic inflammatory bowel diseases and to certain cancers. Recent studies have also shown that 7-ketocholesterol has anti-viral activities, including on SARS-CoV-2, which are, however, lower than those of oxysterols resulting from the oxidation of cholesterol on the side chain. Furthermore, 7-ketocholesterol is increased in the serum of moderately and severely affected COVID-19 patients. In the case of COVID-19, it can be assumed that the antiviral activity of 7-ketocholesterol could be counterbalanced by its toxic effects, including pro-oxidant, pro-inflammatory and pro-coagulant activities that might promote the induction of cell death in alveolar cells. It is therefore suggested that this oxysterol might be involved in the pathophysiology of COVID-19 by contributing to the acute respiratory distress syndrome and promoting a deleterious, even fatal outcome. Thus, 7-ketocholesterol could possibly constitute a lipid biomarker of COVID-19 outcome and counteracting its toxic effects with adjuvant therapies might have beneficial effects in COVID-19 patients.
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Affiliation(s)
- Imen Ghzaiel
- University Bourgogne Franche-Comté, Team 'Biochemistry of the Peroxisome, Inflammation and Lipid Metabolism' EA 7270 / Inserm, 21000 Dijon, France; University of Monastir, Faculty of Medicine, LR12ES05, Lab-NAFS 'Nutrition - Functional Food & Vascular Health', 5000 Monastir, Tunisia; University Tunis-El Manar, Faculty of Sciences of Tunis, 2092 Tunis, Tunisia.
| | - Khouloud Sassi
- University Bourgogne Franche-Comté, Team 'Biochemistry of the Peroxisome, Inflammation and Lipid Metabolism' EA 7270 / Inserm, 21000 Dijon, France; University Tunis El Manar, Laboratory of Onco-Hematology (LR05ES05), Faculty of Medicine, 1007 Tunis, Tunisia.
| | - Amira Zarrouk
- University of Monastir, Faculty of Medicine, LR12ES05, Lab-NAFS 'Nutrition - Functional Food & Vascular Health', 5000 Monastir, Tunisia; University of Sousse, Faculty of Medicine, Sousse, Tunisia.
| | - Thomas Nury
- University Bourgogne Franche-Comté, Team 'Biochemistry of the Peroxisome, Inflammation and Lipid Metabolism' EA 7270 / Inserm, 21000 Dijon, France.
| | - Mohamed Ksila
- University Bourgogne Franche-Comté, Team 'Biochemistry of the Peroxisome, Inflammation and Lipid Metabolism' EA 7270 / Inserm, 21000 Dijon, France; University Tunis-El Manar, Loboratory of Neurophysiology, Cellular Physiopathology and Valorisation of BioMoleecules, LR18ES03, Department of Biologie, Faculty of Sciences, 2092 Tunis, Tunisia.
| | - Valerio Leoni
- Laboratory of Clinical Chemistry, Hospitals of Desio, ASST-Brianza and Department of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy.
| | - Balkiss Bouhaouala-Zahar
- Laboratory of Venoms and Therapeutic Molecules, Pasteur Institute of Tunis & University of Tunis El Manar, 1002 Tunis, Tunisia.
| | - Sonia Hammami
- University of Monastir, Faculty of Medicine, LR12ES05, Lab-NAFS 'Nutrition - Functional Food & Vascular Health', 5000 Monastir, Tunisia.
| | - Mohamed Hammami
- University of Monastir, Faculty of Medicine, LR12ES05, Lab-NAFS 'Nutrition - Functional Food & Vascular Health', 5000 Monastir, Tunisia.
| | - John J Mackrill
- Department of Physiology, School of Medicine, University College Cork, Cork, Ireland.
| | - Mohammad Samadi
- LCPMC-A2, ICPM, Dept of Chemistry, Univ. Lorraine, Metz Technopôle, Metz, France.
| | - Taoufik Ghrairi
- University Tunis-El Manar, Loboratory of Neurophysiology, Cellular Physiopathology and Valorisation of BioMoleecules, LR18ES03, Department of Biologie, Faculty of Sciences, 2092 Tunis, Tunisia.
| | - Anne Vejux
- University Bourgogne Franche-Comté, Team 'Biochemistry of the Peroxisome, Inflammation and Lipid Metabolism' EA 7270 / Inserm, 21000 Dijon, France.
| | - Gérard Lizard
- University Bourgogne Franche-Comté, Team 'Biochemistry of the Peroxisome, Inflammation and Lipid Metabolism' EA 7270 / Inserm, 21000 Dijon, France.
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Nury T, Yammine A, Ghzaiel I, Sassi K, Zarrouk A, Brahmi F, Samadi M, Rup-Jacques S, Vervandier-Fasseur D, Pais de Barros J, Bergas V, Ghosh S, Majeed M, Pande A, Atanasov A, Hammami S, Hammami M, Mackrill J, Nasser B, Andreoletti P, Cherkaoui-Malki M, Vejux A, Lizard G. Attenuation of 7-ketocholesterol- and 7β-hydroxycholesterol-induced oxiapoptophagy by nutrients, synthetic molecules and oils: Potential for the prevention of age-related diseases. Ageing Res Rev 2021; 68:101324. [PMID: 33774195 DOI: 10.1016/j.arr.2021.101324] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 03/10/2021] [Accepted: 03/12/2021] [Indexed: 12/18/2022]
Abstract
Age-related diseases for which there are no effective treatments include cardiovascular diseases; neurodegenerative diseases such as Alzheimer's disease; eye disorders such as cataract and age-related macular degeneration; and, more recently, Severe Acute Respiratory Syndrome (SARS-CoV-2). These diseases are associated with plasma and/or tissue increases in cholesterol derivatives mainly formed by auto-oxidation: 7-ketocholesterol, also known as 7-oxo-cholesterol, and 7β-hydroxycholesterol. The formation of these oxysterols can be considered as a consequence of mitochondrial and peroxisomal dysfunction, leading to increased in oxidative stress, which is accentuated with age. 7-ketocholesterol and 7β-hydroxycholesterol cause a specific form of cytotoxic activity defined as oxiapoptophagy, including oxidative stress and induction of death by apoptosis associated with autophagic criteria. Oxiaptophagy is associated with organelle dysfunction and in particular with mitochondrial and peroxisomal alterations involved in the induction of cell death and in the rupture of redox balance. As the criteria characterizing 7-ketocholesterol- and 7β-hydroxycholesterol-induced cytotoxicity are often simultaneously observed in major age-related diseases (cardiovascular diseases, age-related macular degeneration, Alzheimer's disease) the involvement of these oxysterols in the pathophysiology of the latter seems increasingly likely. It is therefore important to better understand the signalling pathways associated with the toxicity of 7-ketocholesterol and 7β-hydroxycholesterol in order to identify pharmacological targets, nutrients and synthetic molecules attenuating or inhibiting the cytotoxic activities of these oxysterols. Numerous natural cytoprotective compounds have been identified: vitamins, fatty acids, polyphenols, terpenes, vegetal pigments, antioxidants, mixtures of compounds (oils, plant extracts) and bacterial enzymes. However, few synthetic molecules are able to prevent 7-ketocholesterol- and/or 7β-hydroxycholesterol-induced cytotoxicity: dimethyl fumarate, monomethyl fumarate, the tyrosine kinase inhibitor AG126, memantine, simvastatine, Trolox, dimethylsufoxide, mangafodipir and mitochondrial permeability transition pore (MPTP) inhibitors. The effectiveness of these compounds, several of which are already in use in humans, makes it possible to consider using them for the treatment of certain age-related diseases associated with increased plasma and/or tissue levels of 7-ketocholesterol and/or 7β-hydroxycholesterol.
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Abstract
Cholesterol is a quantitatively and biologically significant constituent of all mammalian cell membrane, including those that comprise the retina. Retinal cholesterol homeostasis entails the interplay between de novo synthesis, uptake, intraretinal sterol transport, metabolism, and efflux. Defects in these complex processes are associated with several congenital and age-related disorders of the visual system. Herein, we provide an overview of the following topics: (a) cholesterol synthesis in the neural retina; (b) lipoprotein uptake and intraretinal sterol transport in the neural retina and the retinal pigment epithelium (RPE); (c) cholesterol efflux from the neural retina and the RPE; and (d) biology and pathobiology of defects in sterol synthesis and sterol oxidation in the neural retina and the RPE. We focus, in particular, on studies involving animal models of monogenic disorders pertinent to the above topics, as well as in vitro models using biochemical, metabolic, and omic approaches. We also identify current knowledge gaps and opportunities in the field that beg further research in this topic area.
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Affiliation(s)
- Sriganesh Ramachandra Rao
- Departments of Ophthalmology and Biochemistry and Neuroscience Graduate Program, Jacobs School of Medicine and Biomedical Sciences, State University of New York- University at Buffalo, Buffalo, NY, USA; Research Service, VA Western NY Healthcare System, Buffalo, NY, USA
| | - Steven J Fliesler
- Departments of Ophthalmology and Biochemistry and Neuroscience Graduate Program, Jacobs School of Medicine and Biomedical Sciences, State University of New York- University at Buffalo, Buffalo, NY, USA; Research Service, VA Western NY Healthcare System, Buffalo, NY, USA.
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Ramirez CM, Taylor AM, Lopez AM, Repa JJ, Turley SD. Delineation of metabolic responses of Npc1 -/-nih mice lacking the cholesterol-esterifying enzyme SOAT2 to acute treatment with 2-hydroxypropyl-β-cyclodextrin. Steroids 2020; 164:108725. [PMID: 32890578 PMCID: PMC7680374 DOI: 10.1016/j.steroids.2020.108725] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 08/14/2020] [Accepted: 08/25/2020] [Indexed: 12/26/2022]
Abstract
Lipids present in lipoproteins cleared from the circulation are processed sequentially by three major proteins within the late endosomal/lysosomal (E/L) compartment of all cells: lysosomal acid lipase (LAL), Niemann-Pick (NPC) C2 and NPC1. When all three of these proteins are functioning normally, unesterified cholesterol (UC) exits the E/L compartment and is used in plasma membrane maintenance and various pathways in the endoplasmic reticulum including esterification by sterol O-acyltransferase 2 (SOAT2) or SOAT1 depending partly on cell type. Mutations in either NPC2 or NPC1 result in continual entrapment of UC and glycosphingolipids leading to neurodegeneration, pulmonary dysfunction, splenomegaly and liver damage. To date, the most effective agent for promoting release of entrapped UC in nearly all organs of NPC1-deficient mice and cats is 2-hydroxypropyl-β-cyclodextrin (2HPβCD). The cytotoxic nature of the liberated UC triggers various defenses including suppression of sterol synthesis and increased esterification. The present studies, using the Npc1-/-nih mouse model, measured the comparative quantitative importance of these two responses in the liver versus the spleen of Npc1-/-: Soat2+/+ and Npc1-/-: Soat2-/- mice in the 24 h following a single acute treatment with 2HPβCD. In the liver but not the spleen of both types of mice suppression of synthesis alone or in combination with increased esterification provided the major defense against the rise in unsequestered cellular UC content. These findings have implications for systemic 2HPβCD treatment in NPC1 patients in view of the purportedly low levels of SOAT2 activity in human liver.
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Affiliation(s)
- Charina M Ramirez
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Anna M Taylor
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Adam M Lopez
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Joyce J Repa
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Stephen D Turley
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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Wu L, Xiong L, Li J, Peng Z, Zhang L, Shi P, Gong Y, Xiao H. Circ-Tulp4 promotes β-cell adaptation to lipotoxicity by regulating soat1 expression. J Mol Endocrinol 2020; 65:149-161. [PMID: 33064661 PMCID: PMC7576671 DOI: 10.1530/jme-20-0079] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Accepted: 09/11/2020] [Indexed: 12/18/2022]
Abstract
This study aimed to identify circular RNAs differentially expressed in the islets of type 2 diabetes (T2DM) models and clarify their roles in the control of β-cell functions. Circular RNAs dysregulated in the islets of diabetic db/db mice were identified by high-throughput RNA sequencing. Then, the expression level of the selected circular RNA circ-Tulp4 was confirmed by real-time PCR in the islets of diabetic models and Min6 cells. MTS, EdU, western blot, flow cytometric analysis, and luciferase assay were performed to investigate the impact of circ-Tulp4 on β-cell functions. This study identified thousands of circular RNAs in mouse pancreatic islets. The circ-Tulp4 level significantly decreased in the diabetic models and altered in the Min6 cells under lipotoxic condition. The modulation of circ-Tulp4 level in Min6 cells regulated cell proliferation. Furthermore, an interaction was demonstrated between circ-Tulp4 and miR-7222-3p, which suppressed the expression of cholesterol esterification-related gene, sterol O-acyltransferase 1 (SOAT1). The accumulation of soat1 activated cyclin D1 expression, thus promoting cell cycle progression. These findings showed that circ-Tulp4 regulated β-cell proliferation via miR-7222-3p/soat1/cyclin D1 signaling. Our research suggested that circ-Tulp4 might be a potential therapeutic intervention for T2DM. Besides, soat1 might be important for β-cell adaptation to lipotoxicity.
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Affiliation(s)
- Liting Wu
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Li Xiong
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Jin Li
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
- Department of Geriatrics, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Zishan Peng
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Luyao Zhang
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Peijie Shi
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Yingying Gong
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
- Department of Geriatrics, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
- Correspondence should be addressed to Y Gong or H Xiao: or
| | - Haipeng Xiao
- Department of Endocrinology and Metabolism, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
- Correspondence should be addressed to Y Gong or H Xiao: or
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Neekhra A, Tran J, Esfahani PR, Schneider K, Pham K, Sharma A, Chwa M, Luthra S, Gramajo AL, Mansoor S, Kuppermann BD, Kenney MC. Memantine, Simvastatin, and Epicatechin Inhibit 7-Ketocholesterol-induced Apoptosis in Retinal Pigment Epithelial Cells But Not Neurosensory Retinal Cells In Vitro. J Ophthalmic Vis Res 2020; 15:470-480. [PMID: 33133437 PMCID: PMC7591846 DOI: 10.18502/jovr.v15i4.7781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 06/21/2020] [Indexed: 11/27/2022] Open
Abstract
Purpose 7-ketocholesterol (7kCh), a natural byproduct of oxidation in lipoprotein deposits is implicated in the pathogenesis of diabetic retinopathy and age-related macular degeneration (AMD). This study was performed to investigate whether several clinical drugs can inhibit 7kCh-induced caspase activation and mitigate its apoptotic effects on retinal cells in vitro. Methods Two populations of retinal cells, human retinal pigment epithelial cells (ARPE-19) and rat neuroretinal cells (R28) were exposed to 7kCh in the presence of the following inhibitors: Z-VAD-FMK (pan-caspase inhibitor), simvastatin, memantine, epicatechin, and Z-IETD-FMK (caspase-8 inhibitor) or Z-ATAD-FMK (caspase-12 inhibitor). Caspase-3/7, -8, and -12 activity levels were measured by fluorochrome caspase assays to quantify cell death. IncuCyte live-cell microscopic images were obtained to quantify cell counts. Results Exposure to 7kCh for 24 hours significantly increased caspase activities for both ARPE-19 and R28 cells (P< 0.05). In ARPE cells, pretreatment with various drugs had significantly lower caspase-3/7, -8, and -12 activities, reported in % change in mean signal intensity (msi): Z-VAD-FMK (48% decrease, P< 0.01), memantine (decreased 47.8% at 1 µM, P = 0.0039 and 81.9% at 1 mM, P< 0.001), simvastatin (decreased 85.3% at 0.01 µM, P< 0.001 and 84.8% at 0.05 µM, P< 0.001) or epicatechin (83.6% decrease, P< 0.05), Z-IETD-FMK (68.1% decrease, P< 0.01), and Z-ATAD-FMK (47.7% decrease, P = 0.0017). In contrast, R28 cells exposed to 7kCh continued to have elevated caspase-3/7, -8, and -12 activities (between 25.7% decrease and 17.5% increase in msi, P> 0.05) regardless of the pretreatment. Conclusion Several current drugs protect ARPE-19 cells but not R28 cells from 7kCh-induced apoptosis, suggesting that a multiple-drug approach is needed to protect both cells types in various retinal diseases.
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Affiliation(s)
- Aneesh Neekhra
- Gavin Herbert Eye Institute, University of California, Irvine, California
| | - Julia Tran
- Gavin Herbert Eye Institute, University of California, Irvine, California
| | - Parsa R Esfahani
- Gavin Herbert Eye Institute, University of California, Irvine, California
| | - Kevin Schneider
- Gavin Herbert Eye Institute, University of California, Irvine, California
| | - Khoa Pham
- Gavin Herbert Eye Institute, University of California, Irvine, California
| | - Ashish Sharma
- Gavin Herbert Eye Institute, University of California, Irvine, California
| | - Marilyn Chwa
- Gavin Herbert Eye Institute, University of California, Irvine, California
| | - Saurabh Luthra
- Gavin Herbert Eye Institute, University of California, Irvine, California
| | - Ana L Gramajo
- Gavin Herbert Eye Institute, University of California, Irvine, California
| | - Saffar Mansoor
- Gavin Herbert Eye Institute, University of California, Irvine, California
| | | | - M Cristina Kenney
- Gavin Herbert Eye Institute, University of California, Irvine, California.,Department of Pathology and Laboratory Medicine, University of California Irvine, Irvine, CA, USA
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Brown AJ, Sharpe LJ, Rogers MJ. Oxysterols: From physiological tuners to pharmacological opportunities. Br J Pharmacol 2020; 178:3089-3103. [PMID: 32335907 DOI: 10.1111/bph.15073] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 04/11/2020] [Accepted: 04/14/2020] [Indexed: 02/06/2023] Open
Abstract
Oxysterols are oxygenated forms of cholesterol generated via autooxidation by free radicals and ROS, or formed enzymically by a variety of enzymes such as those involved in the synthesis of bile acids. Although found at very low concentrations in vivo, these metabolites play key roles in health and disease, particularly in development and regulating immune cell responses, by binding to effector proteins such as LXRα, RORγ and Insig and directly or indirectly regulating transcriptional programmes that affect cell metabolism and function. In this review, we summarise the routes by which oxysterols can be generated and subsequently modified to other oxysterol metabolites and highlight their diverse and profound biological functions and opportunities to alter their levels using pharmacological approaches. LINKED ARTICLES: This article is part of a themed issue on Oxysterols, Lifelong Health and Therapeutics. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.16/issuetoc.
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Affiliation(s)
- Andrew J Brown
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, New South Wales, Australia
| | - Laura J Sharpe
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, New South Wales, Australia
| | - Michael J Rogers
- Garvan Institute of Medical Research and St Vincent's Clinical School, UNSW Sydney, Sydney, New South Wales, Australia
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11
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Vejux A, Abed-Vieillard D, Hajji K, Zarrouk A, Mackrill JJ, Ghosh S, Nury T, Yammine A, Zaibi M, Mihoubi W, Bouchab H, Nasser B, Grosjean Y, Lizard G. 7-Ketocholesterol and 7β-hydroxycholesterol: In vitro and animal models used to characterize their activities and to identify molecules preventing their toxicity. Biochem Pharmacol 2020; 173:113648. [DOI: 10.1016/j.bcp.2019.113648] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 09/30/2019] [Indexed: 12/17/2022]
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Anderson A, Campo A, Fulton E, Corwin A, Jerome WG, O'Connor MS. 7-Ketocholesterol in disease and aging. Redox Biol 2020; 29:101380. [PMID: 31926618 PMCID: PMC6926354 DOI: 10.1016/j.redox.2019.101380] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 11/06/2019] [Accepted: 11/10/2019] [Indexed: 02/08/2023] Open
Abstract
7-Ketocholesterol (7KC) is a toxic oxysterol that is associated with many diseases and disabilities of aging, as well as several orphan diseases. 7KC is the most common product of a reaction between cholesterol and oxygen radicals and is the most concentrated oxysterol found in the blood and arterial plaques of coronary artery disease patients as well as various other disease tissues and cell types. Unlike cholesterol, 7KC consistently shows cytotoxicity to cells and its physiological function in humans or other complex organisms is unknown. Oxysterols, particularly 7KC, have also been shown to diffuse through membranes where they affect receptor and enzymatic function. Here, we will explore the known and proposed mechanisms of pathologies that are associated with 7KC, as well speculate about the future of 7KC as a diagnostic and therapeutic target in medicine.
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13
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Lopez AM, Ramirez CM, Taylor AM, Jones RD, Repa JJ, Turley SD. Ontogenesis and Modulation of Intestinal Unesterified Cholesterol Sequestration in a Mouse Model of Niemann-Pick C1 Disease. Dig Dis Sci 2020; 65:158-167. [PMID: 31312996 DOI: 10.1007/s10620-019-05736-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 07/11/2019] [Indexed: 01/24/2023]
Abstract
BACKGROUND Mutations in the NPC1 gene result in sequestration of unesterified cholesterol (UC) and glycosphingolipids in most tissues leading to multi-organ disease, especially in the brain, liver, lungs, and spleen. Various data from NPC1-deficient mice suggest the small intestine (SI) is comparatively less affected, even in late stage disease. METHODS Using the Npc1nih mouse model, we measured SI weights and total cholesterol (TC) levels in Npc1-/- versus Npc1+/+ mice as a function of age, and then after prolonged ezetimibe-induced inhibition of cholesterol absorption. Next, we determined intestinal levels of UC and esterified cholesterol (EC), and cholesterol synthesis rates in Npc1-/- and Npc1+/+ mice, with and without the cholesterol-esterifying enzyme SOAT2, following a once-only subcutaneous injection with 2-hydroxypropyl-β-cyclodextrin (2HPβCD). RESULTS By ~ 42 days of age, intestinal TC levels averaged ~ 2.1-fold more (mostly UC) in the Npc1-/- versus Npc1+/+ mice with no further increase thereafter. Chronic ezetimibe treatment lowered intestinal TC levels in the Npc1-/- mice by only ~ 16%. In Npc1-/- mice given 2HPβCD 24 h earlier, UC levels fell, EC levels increased (although less so in mice lacking SOAT2), and cholesterol synthesis was suppressed equally in the Npc1-/-:Soat2+/+ and Npc1-/-:Soat2-/- mice. CONCLUSIONS The low and static levels of intestinal UC sequestration in Npc1-/- mice likely reflect the continual sloughing of cells from the mucosa. This sequestration is blunted by about the same extent following a single acute treatment with 2HPβCD as it is by a prolonged ezetimibe-induced block of cholesterol absorption.
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MESH Headings
- 2-Hydroxypropyl-beta-cyclodextrin/pharmacology
- Animals
- Cholesterol/metabolism
- Disease Models, Animal
- Ezetimibe/pharmacology
- Female
- Intestinal Absorption/drug effects
- Intestinal Mucosa/drug effects
- Intestinal Mucosa/metabolism
- Intestine, Small/drug effects
- Intestine, Small/metabolism
- Intracellular Signaling Peptides and Proteins/deficiency
- Intracellular Signaling Peptides and Proteins/genetics
- Male
- Mice, 129 Strain
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Knockout
- Niemann-Pick C1 Protein
- Niemann-Pick Disease, Type C/drug therapy
- Niemann-Pick Disease, Type C/genetics
- Niemann-Pick Disease, Type C/metabolism
- Sterol O-Acyltransferase/genetics
- Sterol O-Acyltransferase/metabolism
- Sterol O-Acyltransferase 2
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Affiliation(s)
- Adam M Lopez
- Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Charina M Ramirez
- Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Anna M Taylor
- Department of Physiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Ryan D Jones
- Department of Physiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
- Department of Pathology, Northwestern University, Chicago, IL, 60611, USA
| | - Joyce J Repa
- Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
- Department of Physiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA
| | - Stephen D Turley
- Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390, USA.
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14
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Yang C, Xie L, Gu Q, Qiu Q, Wu X, Yin L. 7-Ketocholesterol disturbs RPE cells phagocytosis of the outer segment of photoreceptor and induces inflammation through ERK signaling pathway. Exp Eye Res 2019; 189:107849. [DOI: 10.1016/j.exer.2019.107849] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 10/13/2019] [Accepted: 10/18/2019] [Indexed: 10/25/2022]
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15
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Pariente A, Peláez R, Pérez-Sala Á, Larráyoz IM. Inflammatory and cell death mechanisms induced by 7-ketocholesterol in the retina. Implications for age-related macular degeneration. Exp Eye Res 2019; 187:107746. [DOI: 10.1016/j.exer.2019.107746] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 07/25/2019] [Accepted: 07/25/2019] [Indexed: 12/16/2022]
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16
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Tang HY, Wang CH, Ho HY, Wu PT, Hung CL, Huang CY, Wu PR, Yeh YH, Cheng ML. Lipidomics reveals accumulation of the oxidized cholesterol in erythrocytes of heart failure patients. Redox Biol 2017; 14:499-508. [PMID: 29101899 PMCID: PMC5675899 DOI: 10.1016/j.redox.2017.10.020] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 10/21/2017] [Accepted: 10/25/2017] [Indexed: 12/14/2022] Open
Abstract
Lipids play an important role in the pathogenesis of cardiovascular disease. Changes in lipids of erythrocytes are indicative of the outcome of pathophysiological processes. In the present study, we assessed whether the lipid profiles of erythrocytes from heart failure (HF) patients are informative of their disease risk. The lipidomes of erythrocytes from 10 control subjects and 29 patients at different HF stages were analyzed using liquid chromatography time-of-flight mass spectrometry. The lipid composition of erythrocytes obtained from HF patients was significantly different from that of normal controls. The levels of phosphatidylcholines (PCs), phosphatidylethanolamines (PEs), and sphingomyelins decreased in HF erythrocytes as compared with those of control subjects; however, the levels of lysoPCs, lysoPEs, and ceramides increased in HF erythrocytes. Notably, the oxidized cholesterol 7-ketocholesterol (7KCh) accumulated to higher level in HF erythrocytes than in plasma from the same patients. We further validated our findings with a cohort of 115 subjects of control subjects (n=28) and patients (n=87). Mechanistically, 7KCh promoted reactive oxygen species (ROS) formation in cardiomyocytes; and induced their death, probably through an ATF4-dependent pathway. Our findings suggest that erythrocytic 7KCh can be a risk factor for HF, and is probably implicated in its pathophysiology.
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Affiliation(s)
- Hsiang-Yu Tang
- Metabolomics Core Laboratory, Healthy Aging Research Center, Chang Gung University, Taoyuan Taiwan
| | - Chao-Hung Wang
- Heart Failure Research Center, Division of Cardiology, Department of Internal Medicine, Chang Gung Memorial Hospital, Keelung, Taiwan; College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Hung-Yao Ho
- Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan; Clinical Phenome Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | - Pei-Ting Wu
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Chun-Ling Hung
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Cheng-Yu Huang
- Metabolomics Core Laboratory, Healthy Aging Research Center, Chang Gung University, Taoyuan Taiwan
| | - Pei-Ru Wu
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Yung-Hsin Yeh
- Cardiovascular Division, Chang-Gung Memorial Hospital, Chang-Gung University College of Medicine, Chang-Gung University, Taiwan
| | - Mei-Ling Cheng
- Metabolomics Core Laboratory, Healthy Aging Research Center, Chang Gung University, Taoyuan Taiwan; Clinical Phenome Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan; Department of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
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17
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Guziewicz KE, Sinha D, Gómez NM, Zorych K, Dutrow EV, Dhingra A, Mullins RF, Stone EM, Gamm DM, Boesze-Battaglia K, Aguirre GD. Bestrophinopathy: An RPE-photoreceptor interface disease. Prog Retin Eye Res 2017; 58:70-88. [PMID: 28111324 PMCID: PMC5441932 DOI: 10.1016/j.preteyeres.2017.01.005] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 01/16/2017] [Accepted: 01/18/2017] [Indexed: 11/17/2022]
Abstract
Bestrophinopathies, one of the most common forms of inherited macular degenerations, are caused by mutations in the BEST1 gene expressed in the retinal pigment epithelium (RPE). Both human and canine BEST1-linked maculopathies are characterized by abnormal accumulation of autofluorescent material within RPE cells and bilateral macular or multifocal lesions; however, the specific mechanism leading to the formation of these lesions remains unclear. We now provide an overview of the current state of knowledge on the molecular pathology of bestrophinopathies, and explore factors promoting formation of RPE-neuroretinal separations, using the first spontaneous animal model of BEST1-associated retinopathies, canine Best (cBest). Here, we characterize the nature of the autofluorescent RPE cell inclusions and report matching spectral signatures of RPE-associated fluorophores between human and canine retinae, indicating an analogous composition of endogenous RPE deposits in Best Vitelliform Macular Dystrophy (BVMD) patients and its canine disease model. This study also exposes a range of biochemical and structural abnormalities at the RPE-photoreceptor interface related to the impaired cone-associated microvillar ensheathment and compromised insoluble interphotoreceptor matrix (IPM), the major pathological culprits responsible for weakening of the RPE-neuroretina interactions, and consequently, formation of vitelliform lesions. These salient alterations detected at the RPE apical domain in cBest as well as in BVMD- and ARB-hiPSC-RPE model systems provide novel insights into the pathological mechanism of BEST1-linked disorders that will allow for development of critical outcome measures guiding therapeutic strategies for bestrophinopathies.
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Affiliation(s)
- Karina E Guziewicz
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, PA 19104, USA.
| | - Divya Sinha
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA; McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Néstor M Gómez
- Department of Anatomy & Cell Biology, School of Dental Medicine, University of Pennsylvania, PA 19104, USA
| | - Kathryn Zorych
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, PA 19104, USA
| | - Emily V Dutrow
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, PA 19104, USA
| | - Anuradha Dhingra
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, PA 19104, USA
| | - Robert F Mullins
- Department of Ophthalmology & Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Edwin M Stone
- Department of Ophthalmology & Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - David M Gamm
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA; McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Ophthalmology & Visual Sciences, University of Wisconsin-Madison, Madison, WI 53705, USA
| | | | - Gustavo D Aguirre
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, PA 19104, USA
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