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Ha K, Mundt-Machado N, Bisignano P, Pinedo A, Raleigh DR, Loeb G, Reiter JF, Cao E, Delling M. Cilia-enriched oxysterol 7β,27-DHC is required for polycystin ion channel activation. Nat Commun 2024; 15:6468. [PMID: 39085216 PMCID: PMC11291729 DOI: 10.1038/s41467-024-50318-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 06/28/2024] [Indexed: 08/02/2024] Open
Abstract
Polycystin-1 (PC-1) and PC-2 form a heteromeric ion channel complex that is abundantly expressed in primary cilia of renal epithelial cells. This complex functions as a non-selective cation channel, and mutations within the polycystin complex cause autosomal dominant polycystic kidney disease (ADPKD). The spatial and temporal regulation of the polycystin complex within the ciliary membrane remains poorly understood. Using both whole-cell and ciliary patch-clamp recordings, we identify a cilia-enriched oxysterol, 7β,27-dihydroxycholesterol (DHC), that serves as a necessary activator of the polycystin complex. We further identify an oxysterol-binding pocket within PC-2 and showed that mutations within this binding pocket disrupt 7β,27-DHC-dependent polycystin activation. Pharmacologic and genetic inhibition of oxysterol synthesis reduces channel activity in primary cilia. In summary, our findings reveal a regulator of the polycystin complex. This oxysterol-binding pocket in PC-2 may provide a specific target for potential ADPKD therapeutics.
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Affiliation(s)
- Kodaji Ha
- Department of Physiology, University of California San Francisco, San Francisco, CA, USA
| | - Nadine Mundt-Machado
- Department of Physiology, University of California San Francisco, San Francisco, CA, USA
| | - Paola Bisignano
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Aide Pinedo
- Department of Physiology, University of California San Francisco, San Francisco, CA, USA
| | - David R Raleigh
- Department of Radiation Oncology, University of California, San Francisco, San Francisco, CA, USA
| | - Gabriel Loeb
- Department of Medicine, University of California, San Francisco, CA, USA
| | - Jeremy F Reiter
- Department of Biochemistry and Biophysics, Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
| | - Erhu Cao
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Markus Delling
- Department of Physiology, University of California San Francisco, San Francisco, CA, USA.
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2
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Ayadi S, Friedrichs S, Soulès R, Pucheu L, Lütjohann D, Silvente-Poirot S, Poirot M, de Medina P. 27-Hydroxylation of oncosterone by CYP27A1 switches its activity from pro-tumor to anti-tumor. J Lipid Res 2023; 64:100479. [PMID: 37981011 PMCID: PMC10770617 DOI: 10.1016/j.jlr.2023.100479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 11/08/2023] [Accepted: 11/11/2023] [Indexed: 11/21/2023] Open
Abstract
Oncosterone (6-oxo-cholestane-3β,5α-diol; OCDO) is an oncometabolite and a tumor promoter on estrogen receptor alpha-positive breast cancer (ER(+) BC) and triple-negative breast cancers (TN BC). OCDO is an oxysterol formed in three steps from cholesterol: 1) oxygen addition at the double bond to give α- or β- isomers of 5,6-epoxycholestanols (5,6-EC), 2) hydrolyses of the epoxide ring of 5,6-ECs to give cholestane-3β,5α,6β-triol (CT), and 3) oxidation of the C6 hydroxyl of CT to give OCDO. On the other hand, cholesterol can be hydroxylated by CYP27A1 at the ultimate methyl carbon of its side chain to give 27-hydroxycholesterol ((25R)-Cholest-5-ene-3beta,26-diol, 27HC), which is a tumor promoter for ER(+) BC. It is currently unknown whether OCDO and its precursors can be hydroxylated at position C27 by CYP27A1, as is the impact of such modification on the proliferation of ER(+) and TN BC cells. We investigated, herein, whether 27H-5,6-ECs ((25R)-5,6-epoxycholestan-3β,26-diol), 27H-CT ((25R)-cholestane-3β,5α,6β,26-tetrol) and 27H-OCDO ((25R)-cholestane-6-oxo-3β,5α,26-triol) exist as metabolites and can be produced by cells expressing CYP27A1. We report, for the first time, that these compounds exist as metabolites in humans. We give pharmacological and genetic evidence that CYP27A1 is responsible for their production. Importantly, we found that 27-hydroxy-OCDO (27H-OCDO) inhibits BC cell proliferation and blocks OCDO and 27-HC-induced proliferation in BC cells, showing that this metabolic conversion commutes the proliferative properties of OCDO into antiproliferative ones. These data suggest an unprecedented role of CYP27A1 in the control of breast carcinogenesis by inhibiting the tumor promoter activities of oncosterone and 27-HC.
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Affiliation(s)
- Silia Ayadi
- Cancer Research Center of Toulouse (CRCT), Inserm, CNRS, University of Toulouse, Team INOV:"Cholesterol Metabolism and Therapeutic Innovations", Toulouse, France; Equipe labellisée par la Ligue Nationale contre le Cancer, Toulouse, France; French Network for Nutrition Physical Acitivity and Cancer Research (NACRe network), Jouy en Josas, France
| | - Silvia Friedrichs
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Bonn, Germany
| | - Regis Soulès
- Cancer Research Center of Toulouse (CRCT), Inserm, CNRS, University of Toulouse, Team INOV:"Cholesterol Metabolism and Therapeutic Innovations", Toulouse, France; Equipe labellisée par la Ligue Nationale contre le Cancer, Toulouse, France; French Network for Nutrition Physical Acitivity and Cancer Research (NACRe network), Jouy en Josas, France
| | - Laly Pucheu
- Cancer Research Center of Toulouse (CRCT), Inserm, CNRS, University of Toulouse, Team INOV:"Cholesterol Metabolism and Therapeutic Innovations", Toulouse, France; Equipe labellisée par la Ligue Nationale contre le Cancer, Toulouse, France; French Network for Nutrition Physical Acitivity and Cancer Research (NACRe network), Jouy en Josas, France
| | - Dieter Lütjohann
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Bonn, Germany
| | - Sandrine Silvente-Poirot
- Cancer Research Center of Toulouse (CRCT), Inserm, CNRS, University of Toulouse, Team INOV:"Cholesterol Metabolism and Therapeutic Innovations", Toulouse, France.
| | - Marc Poirot
- Cancer Research Center of Toulouse (CRCT), Inserm, CNRS, University of Toulouse, Team INOV:"Cholesterol Metabolism and Therapeutic Innovations", Toulouse, France; Equipe labellisée par la Ligue Nationale contre le Cancer, Toulouse, France; French Network for Nutrition Physical Acitivity and Cancer Research (NACRe network), Jouy en Josas, France.
| | - Philippe de Medina
- Cancer Research Center of Toulouse (CRCT), Inserm, CNRS, University of Toulouse, Team INOV:"Cholesterol Metabolism and Therapeutic Innovations", Toulouse, France; Equipe labellisée par la Ligue Nationale contre le Cancer, Toulouse, France; French Network for Nutrition Physical Acitivity and Cancer Research (NACRe network), Jouy en Josas, France.
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3
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Liu Y, Yang X, Xiao F, Jie F, Zhang Q, Liu Y, Xiao H, Lu B. Dietary cholesterol oxidation products: Perspectives linking food processing and storage with health implications. Compr Rev Food Sci Food Saf 2021; 21:738-779. [PMID: 34953101 DOI: 10.1111/1541-4337.12880] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 11/08/2021] [Accepted: 11/09/2021] [Indexed: 12/23/2022]
Abstract
Dietary cholesterol oxidation products (COPs) are heterogeneous compounds formed during the processing and storage of cholesterol-rich foods, such as seafood, meat, eggs, and dairy products. With the increased intake of COPs-rich foods, the concern about health implications of dietary COPs is rising. Dietary COPs may exert deleterious effects on human health to induce several inflammatory diseases including atherosclerosis, neurodegenerative diseases, and inflammatory bowel diseases. Thus, knowledge regarding the effects of processing and storage conditions leading to formation of COPs is needed to reduce the levels of COPs in foods. Efficient methodologies to determine COPs in foods are also essential. More importantly, the biological roles of dietary COPs in human health and effects of phytochemicals on dietary COPs-induced diseases need to be established. This review summarizes the recent information on dietary COPs including their formation in foods during their processing and storage, analytical methods of determination of COPs, metabolic fate, implications for human health, and beneficial interventions by phytochemicals. The formation of COPs is largely dependent on the heating temperature, storage time, and food matrices. Alteration of food processing and storage conditions is one of the potent strategies to restrict hazardous dietary COPs from forming, including maintaining relatively low temperatures, shorter processing or storage time, and the appropriate addition of antioxidants. Once absorbed into the circulation, dietary COPs can contribute to the progression of several inflammatory diseases, where the absorbed dietary COPs may induce inflammation, apoptosis, and autophagy in cells in the target organs or tissues. Improved intake of phytochemicals may be an effective strategy to reduce the hazardous effects of dietary COPs.
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Affiliation(s)
- Yan Liu
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Key Laboratory for Agro-Products Nutritional Evaluation of Ministry of Agriculture and Rural Affairs, Key Laboratory of Agro-Products Postharvest Handling of Ministry of Agriculture and Rural Affairs, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang International Scientific and Technological Cooperation Base of Health Food Manufacturing and Quality Control, Zhejiang University, Hangzhou, China.,Fuli Institute of Food Science, Zhejiang University, Hangzhou, China.,Ningbo Research Institute, Zhejiang University, Ningbo, China
| | - Xuan Yang
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Key Laboratory for Agro-Products Nutritional Evaluation of Ministry of Agriculture and Rural Affairs, Key Laboratory of Agro-Products Postharvest Handling of Ministry of Agriculture and Rural Affairs, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang International Scientific and Technological Cooperation Base of Health Food Manufacturing and Quality Control, Zhejiang University, Hangzhou, China.,Fuli Institute of Food Science, Zhejiang University, Hangzhou, China.,Ningbo Research Institute, Zhejiang University, Ningbo, China
| | - Fan Xiao
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Key Laboratory for Agro-Products Nutritional Evaluation of Ministry of Agriculture and Rural Affairs, Key Laboratory of Agro-Products Postharvest Handling of Ministry of Agriculture and Rural Affairs, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang International Scientific and Technological Cooperation Base of Health Food Manufacturing and Quality Control, Zhejiang University, Hangzhou, China.,Fuli Institute of Food Science, Zhejiang University, Hangzhou, China.,Ningbo Research Institute, Zhejiang University, Ningbo, China
| | - Fan Jie
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Key Laboratory for Agro-Products Nutritional Evaluation of Ministry of Agriculture and Rural Affairs, Key Laboratory of Agro-Products Postharvest Handling of Ministry of Agriculture and Rural Affairs, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang International Scientific and Technological Cooperation Base of Health Food Manufacturing and Quality Control, Zhejiang University, Hangzhou, China.,Fuli Institute of Food Science, Zhejiang University, Hangzhou, China.,Ningbo Research Institute, Zhejiang University, Ningbo, China
| | - Qinjun Zhang
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Key Laboratory for Agro-Products Nutritional Evaluation of Ministry of Agriculture and Rural Affairs, Key Laboratory of Agro-Products Postharvest Handling of Ministry of Agriculture and Rural Affairs, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang International Scientific and Technological Cooperation Base of Health Food Manufacturing and Quality Control, Zhejiang University, Hangzhou, China.,Fuli Institute of Food Science, Zhejiang University, Hangzhou, China.,Ningbo Research Institute, Zhejiang University, Ningbo, China
| | - Yuqi Liu
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Key Laboratory for Agro-Products Nutritional Evaluation of Ministry of Agriculture and Rural Affairs, Key Laboratory of Agro-Products Postharvest Handling of Ministry of Agriculture and Rural Affairs, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang International Scientific and Technological Cooperation Base of Health Food Manufacturing and Quality Control, Zhejiang University, Hangzhou, China.,Fuli Institute of Food Science, Zhejiang University, Hangzhou, China.,Ningbo Research Institute, Zhejiang University, Ningbo, China
| | - Hang Xiao
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Key Laboratory for Agro-Products Nutritional Evaluation of Ministry of Agriculture and Rural Affairs, Key Laboratory of Agro-Products Postharvest Handling of Ministry of Agriculture and Rural Affairs, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang International Scientific and Technological Cooperation Base of Health Food Manufacturing and Quality Control, Zhejiang University, Hangzhou, China.,Department of Food Science, University of Massachusetts, Amherst, Massachusetts, USA
| | - Baiyi Lu
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Key Laboratory for Agro-Products Nutritional Evaluation of Ministry of Agriculture and Rural Affairs, Key Laboratory of Agro-Products Postharvest Handling of Ministry of Agriculture and Rural Affairs, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang International Scientific and Technological Cooperation Base of Health Food Manufacturing and Quality Control, Zhejiang University, Hangzhou, China.,Fuli Institute of Food Science, Zhejiang University, Hangzhou, China.,Ningbo Research Institute, Zhejiang University, Ningbo, China
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4
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Morris DJ, Brem AS, Odermatt A. Modulation of 11β-hydroxysteroid dehydrogenase functions by the cloud of endogenous metabolites in a local microenvironment: The glycyrrhetinic acid-like factor (GALF) hypothesis. J Steroid Biochem Mol Biol 2021; 214:105988. [PMID: 34464733 DOI: 10.1016/j.jsbmb.2021.105988] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 08/08/2021] [Accepted: 08/25/2021] [Indexed: 01/09/2023]
Abstract
11β-Hydroxysteroid dehydrogenase (11β-HSD)-dependent conversion of cortisol to cortisone and corticosterone to 11-dehydrocorticosterone are essential in regulating transcriptional activities of mineralocorticoid receptors (MR) and glucocorticoid receptors (GR). Inhibition of 11β-HSD by glycyrrhetinic acid metabolites, bioactive components of licorice, causes sodium retention and potassium loss, with hypertension characterized by low renin and aldosterone. Essential hypertension is a major disease, mostly with unknown underlying mechanisms. Here, we discuss a putative mechanism for essential hypertension, the concept that endogenous steroidal compounds acting as glycyrrhetinic acid-like factors (GALFs) inhibit 11β-HSD dehydrogenase, and allow for glucocorticoid-induced MR and GR activation with resulting hypertension. Initially, several metabolites of adrenally produced glucocorticoids and mineralocorticoids were shown to be potent 11β-HSD inhibitors. Such GALFs include modifications in the A-ring and/or at positions 3, 7 and 21 of the steroid backbone. These metabolites may be formed in peripheral tissues or by gut microbiota. More recently, metabolites of 11β-hydroxy-Δ4androstene-3,17-dione and 7-oxygenated oxysterols have been identified as potent 11β-HSD inhibitors. In a living system, 11β-HSD isoforms are not exposed to a single substrate but to several substrates, cofactors, and various inhibitors simultaneously, all at different concentrations depending on physical state, tissue and cell type. We propose that this "cloud" of steroids and steroid-like substances in the microenvironment determines the 11β-HSD-dependent control of MR and GR activity. A dysregulated composition of this cloud of metabolites in the respective microenvironment needs to be taken into account when investigating disease mechanisms, for forms of low renin, low aldosterone hypertension.
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Affiliation(s)
- David J Morris
- Department of Pathology and Laboratory Medicine, The Miriam Hospital, Warren Alpert Medical School of Brown University, Providence, RI, USA.
| | - Andrew S Brem
- Division of Kidney Diseases and Hypertension, Warren Alpert Medical School of Brown University, Providence, RI, USA.
| | - Alex Odermatt
- Swiss Centre for Applied Human Toxicology and Division of Molecular and Systems Toxicology, Department of Pharmaceutical Sciences, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland.
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5
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Ravi S, Duraisamy P, Krishnan M, Martin LC, Manikandan B, Raman T, Sundaram J, Arumugam M, Ramar M. An insight on 7- ketocholesterol mediated inflammation in atherosclerosis and potential therapeutics. Steroids 2021; 172:108854. [PMID: 33930389 DOI: 10.1016/j.steroids.2021.108854] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 04/16/2021] [Accepted: 04/20/2021] [Indexed: 11/24/2022]
Abstract
7-ketocholesterol, a toxic oxidative product of oxysterol is a causative agent of several diseases and disabilities concomitant to aging including cardiovascular diseases like atherosclerosis. Auto-oxidation of cholesterol esters present in low-density lipoprotein (LDL) deposits lead to the formation of oxidized LDL (Ox-LDL) along with its byproducts, namely 7KCh. It is predominantly found in atherosclerotic plaque and also found to be more atherogenic than cholesterol by being cytotoxic, interfering with cellular homeostasis. This makes it a serious threat by being the foremost cause of morbidity and mortality worldwide and is likely to become more serious during forth coming years. It involves in mediating inflammatory mechanisms characterized by the advancement of fibroatheroma plaques. The atherosclerotic lesion is composed of Ox-LDL along with fibrotic mass consisting of immune cells and molecules. Macrophages being the specialized phagocytic cells, contribute to removal of detrimental contents of the lesion along with accumulated lipids leading to alteration of its biology and functionality due to its plasticity. Here, we have explored the known as well as proposed mechanisms involved with 7KCh associated atherogenesis along with potential therapeutic strategies for targeting 7KCh as a diagnostic and target in medicine.
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Affiliation(s)
- Sangeetha Ravi
- Department of Zoology, University of Madras, Guindy Campus, Chennai 600 025, India
| | | | - Mahalakshmi Krishnan
- Department of Zoology, University of Madras, Guindy Campus, Chennai 600 025, India
| | - Livya C Martin
- Department of Zoology, University of Madras, Guindy Campus, Chennai 600 025, India
| | - Beulaja Manikandan
- Department of Biochemistry, Annai Veilakanni's College for Women, Chennai 600015, India
| | - Thiagarajan Raman
- Department of Advanced Zoology and Biotechnology, Ramakrishna Mission Vivekananda College, Mylapore, Chennai 600004, India
| | - Janarthanan Sundaram
- Department of Zoology, University of Madras, Guindy Campus, Chennai 600 025, India
| | - Munusamy Arumugam
- Department of Zoology, University of Madras, Guindy Campus, Chennai 600 025, India
| | - Manikandan Ramar
- Department of Zoology, University of Madras, Guindy Campus, Chennai 600 025, India.
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6
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Samadi A, Sabuncuoglu S, Samadi M, Isikhan SY, Chirumbolo S, Peana M, Lay I, Yalcinkaya A, Bjørklund G. A Comprehensive Review on Oxysterols and Related Diseases. Curr Med Chem 2021; 28:110-136. [PMID: 32175830 DOI: 10.2174/0929867327666200316142659] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Revised: 11/09/2019] [Accepted: 11/10/2019] [Indexed: 11/22/2022]
Abstract
The present review aims to provide a complete and comprehensive summary of current literature relevant to oxysterols and related diseases. Oxidation of cholesterol leads to the formation of a large number of oxidized products, generally known as oxysterols. They are intermediates in the biosynthesis of bile acids, steroid hormones, and 1,25- dihydroxyvitamin D3. Although oxysterols are considered as metabolic intermediates, there is a growing body of evidence that many of them are bioactive, and their absence or excess may be part of the cause of a disease phenotype. These compounds derive from either enzymatic or non-enzymatic oxidation of cholesterol. This study provides comprehensive information about the structures, formation, and types of oxysterols even when involved in certain disease states, focusing on their effects on metabolism and linkages with these diseases. The role of specific oxysterols as mediators in various disorders, such as degenerative (age-related) and cancer-related disorders, has now become clearer. Oxysterol levels may be employed as suitable markers for the diagnosis of specific diseases or in predicting the incidence rate of diseases, such as diabetes mellitus, Alzheimer's disease, multiple sclerosis, osteoporosis, lung cancer, breast cancer, and infertility. However, further investigations may be required to confirm these mentioned possibilities.
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Affiliation(s)
- Afshin Samadi
- Faculty of Pharmaceutical Sciences, University of Iceland, Reykjavik, Iceland
| | - Suna Sabuncuoglu
- Department of Pharmaceutical Toxicology, Faculty of Pharmacy, Hacettepe University, Ankara, Turkey
| | - Mahshid Samadi
- Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Selen Yilmaz Isikhan
- Vocational Higher School of Social Sciences, Hacettepe University, Ankara, Turkey
| | - Salvatore Chirumbolo
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Massimiliano Peana
- Department of Chemistry and Pharmacy, University of Sassari, Sassari, Italy
| | - Incilay Lay
- Department of Medical Biochemistry, Faculty of Medicine, Hacettepe University, Ankara, Turkey
| | - Ahmet Yalcinkaya
- Department of Medical Biochemistry, Faculty of Medicine, Hacettepe University, Ankara, Turkey
| | - Geir Bjørklund
- Council for Nutritional and Environmental Medicine (CONEM), Mo i Rana, Norway
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7
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Effect of Ergothioneine on 7-Ketocholesterol-Induced Endothelial Injury. Neuromolecular Med 2020; 23:184-198. [PMID: 33067719 PMCID: PMC7567423 DOI: 10.1007/s12017-020-08620-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 10/06/2020] [Indexed: 12/21/2022]
Abstract
Ergothioneine (ET) is a naturally occurring antioxidant that is synthesized by non-yeast fungi and certain bacteria. ET is not synthesized by animals, including humans, but is avidly taken up from the diet, especially from mushrooms. In the current study, we elucidated the effect of ET on the hCMEC/D3 human brain endothelial cell line. Endothelial cells are exposed to high levels of the cholesterol oxidation product, 7-ketocholesterol (7KC), in patients with cardiovascular disease and diabetes, and this process is thought to mediate pathological inflammation. 7KC induces a dose-dependent loss of cell viability and an increase in apoptosis and necrosis in the endothelial cells. A relocalization of the tight junction proteins, zonula occludens-1 (ZO-1) and claudin-5, towards the nucleus of the cells was also observed. These effects were significantly attenuated by ET. In addition, 7KC induces marked increases in the mRNA expression of pro-inflammatory cytokines, IL-1β IL-6, IL-8, TNF-α and cyclooxygenase-2 (COX2), as well as COX2 enzymatic activity, and these were significantly reduced by ET. Moreover, the cytoprotective and anti-inflammatory effects of ET were significantly reduced by co-incubation with an inhibitor of the ET transporter, OCTN1 (VHCL). This shows that ET needs to enter the endothelial cells to have a protective effect and is unlikely to act via extracellular neutralizing of 7KC. The protective effect on inflammation in brain endothelial cells suggests that ET might be useful as a nutraceutical for the prevention or management of neurovascular diseases, such as stroke and vascular dementia. Moreover, the ability of ET to cross the blood-brain barrier could point to its usefulness in combatting 7KC that is produced in the CNS during neuroinflammation, e.g. after excitotoxicity, in chronic neurodegenerative diseases, and possibly COVID-19-related neurologic complications.
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8
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Wang X, Li Y, Xia X, Zhang M, Ge C, Xia X, Xiao H, Xu S. Mutagenicity of 7-ketocholesterol in CHO cells: The role of lipid peroxidation. Toxicology 2020; 446:152587. [PMID: 33017620 DOI: 10.1016/j.tox.2020.152587] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 09/10/2020] [Accepted: 09/14/2020] [Indexed: 02/07/2023]
Abstract
As an important cholesterol oxide, 7-ketocholesterol plays a deleterious role in the occurrence of cancer. Although the fact had been proved that 7-ketocholesterol could induce several biological phenomena, including apoptosis, DNA damage, et al., this issue whether 7-ketocholesterol led to mutagenesis in mammalian cells remains largely unexplored. Here, we investigated the major role of lipid peroxidation in the genotoxic response to 7-ketocholesterol in chinese hamster ovary (CHO) cells. The results showed that 7-ketocholesterol induced gene mutation and DNA double-strand breaks (DSBs) in concentration- and time-dependent manner. After CHO cells were treated with 25 μM 7-ketocholesterol for 48 h, the mutation frequency at hprt gene loci and the level of γ-H2AX protein were both significantly increased. Exposure to 7-ketocholesterol resulted in a concentration-dependent increase in the apoptotic rate and the protein expression of cleaved caspase-3 and -7 in CHO cells. Moreover, a significant increase of superoxide dismutase (SOD) activity and content of malondialdehyde (MDA) was also observed. Using a inhibitor of lipid peroxidation (butylated hydroxytoluene), it was found to remarkably inhibit the genotoxicity and MDA levels caused by 7-ketocholesterol. These findings indicated that lipid peroxidation was involved in the mutagenic process of 7-ketocholesterol in CHO cells.
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Affiliation(s)
- Xiaofei Wang
- School of Biology, Food and Environment, Hefei University, Hefei, 230601, PR China
| | - Yintao Li
- School of Biology, Food and Environment, Hefei University, Hefei, 230601, PR China; Anhui Province Key Laboratory of Environmental Toxicology and Pollution Control Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, 230031, PR China
| | - Xuanyi Xia
- School of Biology, Food and Environment, Hefei University, Hefei, 230601, PR China
| | - Min Zhang
- School of Biology, Food and Environment, Hefei University, Hefei, 230601, PR China
| | - Chunmei Ge
- School of Biology, Food and Environment, Hefei University, Hefei, 230601, PR China
| | - Xiaoxiao Xia
- School of Biology, Food and Environment, Hefei University, Hefei, 230601, PR China
| | - Hourong Xiao
- School of Biology, Food and Environment, Hefei University, Hefei, 230601, PR China.
| | - Shengmin Xu
- Institute of Physical Science and Information Technology, Anhui University, Hefei, 230601, PR China.
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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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10
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Griffiths WJ, Yutuc E, Abdel-Khalik J, Crick PJ, Hearn T, Dickson A, Bigger BW, Hoi-Yee Wu T, Goenka A, Ghosh A, Jones SA, Covey DF, Ory DS, Wang Y. Metabolism of Non-Enzymatically Derived Oxysterols: Clues from sterol metabolic disorders. Free Radic Biol Med 2019; 144:124-133. [PMID: 31009661 PMCID: PMC6863434 DOI: 10.1016/j.freeradbiomed.2019.04.020] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 04/12/2019] [Accepted: 04/16/2019] [Indexed: 12/18/2022]
Abstract
Cholestane-3β,5α,6β-triol (3β,5α,6β-triol) is formed from cholestan-5,6-epoxide (5,6-EC) in a reaction catalysed by cholesterol epoxide hydrolase, following formation of 5,6-EC through free radical oxidation of cholesterol. 7-Oxocholesterol (7-OC) and 7β-hydroxycholesterol (7β-HC) can also be formed by free radical oxidation of cholesterol. Here we investigate how 3β,5α,6β-triol, 7-OC and 7β-HC are metabolised to bile acids. We show, by monitoring oxysterol metabolites in plasma samples rich in 3β,5α,6β-triol, 7-OC and 7β-HC, that these three oxysterols fall into novel branches of the acidic pathway of bile acid biosynthesis becoming (25R)26-hydroxylated then carboxylated, 24-hydroxylated and side-chain shortened to give the final products 3β,5α,6β-trihydroxycholanoic, 3β-hydroxy-7-oxochol-5-enoic and 3β,7β-dihydroxychol-5-enoic acids, respectively. The intermediates in these pathways may be causative of some phenotypical features of, and/or have diagnostic value for, the lysosomal storage diseases, Niemann Pick types C and B and lysosomal acid lipase deficiency. Free radical derived oxysterols are metabolised in human to unusual bile acids via novel branches of the acidic pathway, intermediates in these pathways are observed in plasma.
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Affiliation(s)
- William J Griffiths
- Institute of Life Science, Swansea University Medical School, Singleton Park, Swansea, SA2 8PP, UK.
| | - Eylan Yutuc
- Institute of Life Science, Swansea University Medical School, Singleton Park, Swansea, SA2 8PP, UK
| | - Jonas Abdel-Khalik
- Institute of Life Science, Swansea University Medical School, Singleton Park, Swansea, SA2 8PP, UK
| | - Peter J Crick
- Institute of Life Science, Swansea University Medical School, Singleton Park, Swansea, SA2 8PP, UK
| | - Thomas Hearn
- Institute of Life Science, Swansea University Medical School, Singleton Park, Swansea, SA2 8PP, UK
| | - Alison Dickson
- Institute of Life Science, Swansea University Medical School, Singleton Park, Swansea, SA2 8PP, UK
| | - Brian W Bigger
- Stem Cell & Neurotherapies, Division of Cell Matrix Biology and Regenerative Medicine, Stopford Building, Oxford Road, University of Manchester, Manchester, M13 9PT, UK
| | - Teresa Hoi-Yee Wu
- Manchester Centre for Genomic Medicine, 6th Floor, St Mary's Hospital, Central Manchester Foundation Trust, University of Manchester, Oxford Road, Manchester, M13 9WL, UK
| | - Anu Goenka
- Manchester Centre for Genomic Medicine, 6th Floor, St Mary's Hospital, Central Manchester Foundation Trust, University of Manchester, Oxford Road, Manchester, M13 9WL, UK
| | - Arunabha Ghosh
- Manchester Centre for Genomic Medicine, 6th Floor, St Mary's Hospital, Central Manchester Foundation Trust, University of Manchester, Oxford Road, Manchester, M13 9WL, UK
| | - Simon A Jones
- Manchester Centre for Genomic Medicine, 6th Floor, St Mary's Hospital, Central Manchester Foundation Trust, University of Manchester, Oxford Road, Manchester, M13 9WL, UK
| | - Douglas F Covey
- Department of Developmental Biology, Washington University School of Medicine, St Louis, MO, 63110, USA
| | - Daniel S Ory
- Diabetic Cardiovascular Disease Center, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Yuqin Wang
- Institute of Life Science, Swansea University Medical School, Singleton Park, Swansea, SA2 8PP, UK.
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11
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Beck KR, Inderbinen SG, Kanagaratnam S, Kratschmar DV, Jetten AM, Yamaguchi H, Odermatt A. 11β-Hydroxysteroid dehydrogenases control access of 7β,27-dihydroxycholesterol to retinoid-related orphan receptor γ. J Lipid Res 2019; 60:1535-1546. [PMID: 31273032 PMCID: PMC6718442 DOI: 10.1194/jlr.m092908] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 06/24/2019] [Indexed: 12/15/2022] Open
Abstract
Oxysterols previously were considered intermediates of bile acid and steroid hormone biosynthetic pathways. However, recent research has emphasized the roles of oxysterols in essential physiologic processes and in various diseases. Despite these discoveries, the metabolic pathways leading to the different oxysterols are still largely unknown and the biosynthetic origin of several oxysterols remains unidentified. Earlier studies demonstrated that the glucocorticoid metabolizing enzymes, 11β-hydroxysteroid dehydrogenase (11β-HSD) types 1 and 2, interconvert 7-ketocholesterol (7kC) and 7β-hydroxycholesterol (7βOHC). We examined the role of 11β-HSDs in the enzymatic control of the intracellular availability of 7β,27-dihydroxycholesterol (7β27OHC), a retinoid-related orphan receptor γ (RORγ) ligand. We used microsomal preparations of cells expressing recombinant 11β-HSD1 and 11β-HSD2 to assess whether 7β27OHC and 7-keto,27-hydroxycholesterol (7k27OHC) are substrates of these enzymes. Binding of 7β27OHC and 7k27OHC to 11β-HSDs was studied by molecular modeling. To our knowledge, the stereospecific oxoreduction of 7k27OHC to 7β27OHC by human 11β-HSD1 and the reverse oxidation reaction of 7β27OHC to 7k27OHC by human 11β-HSD2 were demonstrated for the first time. Apparent enzyme affinities of 11β-HSDs for these novel substrates were equal to or higher than those of the glucocorticoids. This is supported by the fact that 7k27OHC and 7β27OHC are potent inhibitors of the 11β-HSD1-dependent oxoreduction of cortisone and the 11β-HSD2-dependent oxidation of cortisol, respectively. Furthermore, molecular docking calculations explained stereospecific enzyme activities. Finally, using an inducible RORγ reporter system, we showed that 11β-HSD1 and 11β-HSD2 controlled RORγ activity. These findings revealed a novel glucocorticoid-independent prereceptor regulation mechanism by 11β-HSDs that warrants further investigation.
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Affiliation(s)
- Katharina R Beck
- Division of Molecular and Systems Toxicology, Department of Pharmaceutical Sciences, University of Basel, 4056 Basel, Switzerland
| | - Silvia G Inderbinen
- Division of Molecular and Systems Toxicology, Department of Pharmaceutical Sciences, University of Basel, 4056 Basel, Switzerland
| | - Sharavan Kanagaratnam
- Division of Molecular and Systems Toxicology, Department of Pharmaceutical Sciences, University of Basel, 4056 Basel, Switzerland
| | - Denise V Kratschmar
- Division of Molecular and Systems Toxicology, Department of Pharmaceutical Sciences, University of Basel, 4056 Basel, Switzerland
| | - Anton M Jetten
- Immunity, Inflammation, and Disease Laboratory National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709
| | - Hideaki Yamaguchi
- Department of Applied Biological Chemistry Meijo University, Nagoya 468-8502, Japan
| | - Alex Odermatt
- Division of Molecular and Systems Toxicology, Department of Pharmaceutical Sciences, University of Basel, 4056 Basel, Switzerland.
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12
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Holy P, Kloudova A, Soucek P. Importance of genetic background of oxysterol signaling in cancer. Biochimie 2018; 153:109-138. [DOI: 10.1016/j.biochi.2018.04.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 04/27/2018] [Indexed: 12/14/2022]
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13
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Vurusaner B, Gargiulo S, Testa G, Gamba P, Leonarduzzi G, Poli G, Basaga H. The role of autophagy in survival response induced by 27-hydroxycholesterol in human promonocytic cells. Redox Biol 2018; 17:400-410. [PMID: 29879549 PMCID: PMC5986166 DOI: 10.1016/j.redox.2018.05.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 05/16/2018] [Accepted: 05/21/2018] [Indexed: 11/25/2022] Open
Abstract
Autophagy has been shown to be stimulated in advanced atherosclerotic plaques by metabolic stress, inflammation and oxidized lipids. The lack of published studies addressing the potential stimulation of pro-survival autophagy by oxysterols, a family of cholesterol oxidation products, has prompted our study. Thus, the goal of the current study is to elucidate the molecular mechanism of the autophagy induced by 27-hydroxycholesterol (27-OH), that is one of the most abundant oxysterols in advanced atherosclerotic lesions, and to assess whether the pro-oxidant effect of the oxysterol is involved in the given response. Here we showed that 27-OH, in a low micromolar range, activates a pro-survival autophagic response in terms of increased LC3 II/LC3 I ratio and Beclin 1, that depends on the up-regulation of extracellular signal-regulated kinase (ERK) and phosphoinositide 3-kinase (PI3K)/Akt pathways as a potential result of an intracellular reactive oxygen species increase provoked by the oxysterol in human promonocytic U937 cells. Moreover, 27-OH induced autophagy is dependent on the relation between nuclear factor erythroid 2 p45-related factor 2 (Nrf2)-dependent antioxidant response and p62. The data obtained highlight the involvement of cholesterol oxidation products in the pathogenesis of oxidative stress related chronic diseases like atherosclerosis. Therefore, deeply understanding the complex mechanism and generating synthetic or natural molecules targeting this survival mechanism might be very promising tools in the prevention of such diseases.
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Affiliation(s)
- Beyza Vurusaner
- Biological Sciences and Bioengineering Program, Faculty of Engineering and Natural Sciences, Sabanci University, Orhanli-Tuzla, 34956 Istanbul, Turkey.
| | - Simona Gargiulo
- Department of Clinical and Biological Sciences, University of Torino, Torino, Italy.
| | - Gabriella Testa
- Department of Clinical and Biological Sciences, University of Torino, Torino, Italy.
| | - Paola Gamba
- Department of Clinical and Biological Sciences, University of Torino, Torino, Italy.
| | - Gabriella Leonarduzzi
- Department of Clinical and Biological Sciences, University of Torino, Torino, Italy.
| | - Giuseppe Poli
- Department of Clinical and Biological Sciences, University of Torino, Torino, Italy.
| | - Huveyda Basaga
- Biological Sciences and Bioengineering Program, Faculty of Engineering and Natural Sciences, Sabanci University, Orhanli-Tuzla, 34956 Istanbul, Turkey.
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14
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Kulig W, Cwiklik L, Jurkiewicz P, Rog T, Vattulainen I. Cholesterol oxidation products and their biological importance. Chem Phys Lipids 2016; 199:144-160. [DOI: 10.1016/j.chemphyslip.2016.03.001] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Revised: 03/02/2016] [Accepted: 03/03/2016] [Indexed: 12/14/2022]
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15
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Ghosh S, Khare SK. Biodegradation of cytotoxic 7-Ketocholesterol by Pseudomonas aeruginosa PseA. BIORESOURCE TECHNOLOGY 2016; 213:44-49. [PMID: 27020128 DOI: 10.1016/j.biortech.2016.03.079] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Revised: 03/11/2016] [Accepted: 03/12/2016] [Indexed: 06/05/2023]
Abstract
The present study aims to degrade 7-Ketocholesterol (7KC), a major oxysterol implicated in many age-related disorders, through microbial means and find candidate enzymes involved for further application in food systems and as a therapeutic. During initial screening of previously isolated bacteria from our laboratory, Pseudomonas aeruginosa PseA was found to be a potential degrader strain using 7KC as a sole carbon source. Under optimized conditions, it is able to degrade 88% of an initial concentration of 1000ppm (1g/l) 7KC. Preliminary in vitro studies with extra-cellular extract has shown degradation of the compound, thus reinforcing the occurrence of suitable enzymatic systems involved in the process. We have been able to identify cholesterol oxidase as one such potential enzyme. Some intermediate products of degradation have also been identified. This is the first detailed report of 7KC degradation by a P. aeruginosa strain.
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Affiliation(s)
- Shubhrima Ghosh
- Enzyme and Microbial Biochemistry Laboratory, Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - S K Khare
- Enzyme and Microbial Biochemistry Laboratory, Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
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16
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Vurusaner B, Gamba P, Gargiulo S, Testa G, Staurenghi E, Leonarduzzi G, Poli G, Basaga H. Nrf2 antioxidant defense is involved in survival signaling elicited by 27-hydroxycholesterol in human promonocytic cells. Free Radic Biol Med 2016; 91:93-104. [PMID: 26689473 DOI: 10.1016/j.freeradbiomed.2015.12.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 12/04/2015] [Accepted: 12/07/2015] [Indexed: 01/08/2023]
Abstract
Cholesterol oxidation products such as oxysterols are considered critical factors in the atherosclerotic plaque formation since they induce oxidative stress, inflammation and apoptotic cell death. 27-hydroxycholesterol (27-OH) is one of the most represented oxysterols in atherosclerotic lesions. We recently showed that relatively low concentrations of 27-OH generated a strong survival signaling through an early and transient increase of cellular ROS level, that enhanced MEK-ERK/PI3K-Akt phosphorylation, in turn responsible of a sustained quenching of ROS production. It remains to identify the link between ERK/Akt up-regulation and the consequent quenching effect on ROS intracellular level that efficiently and markedly delay the pro-apoptotic effect of the oxysterol. Here we report on the potent activation of Nrf2 redox-sensitive transcription factor by low micromolar amount of 27-OH added to U937 promonocytic cells. The 27-OH-exerted induction of Nrf2 and subsequently of the target genes, HO-1 and NQO-1, was proved to be: (i) dependent upon the activation of ERK and Akt pathways, (ii) directly responsible for the quenching of intracellular oxidative stress and by this way (iii) ultimately responsible for the observed oxysterol-induced pro-survival response.
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Affiliation(s)
- Beyza Vurusaner
- Biological Sciences and Bioengineering Program, Faculty of Engineering and Natural Sciences, Sabanci University, Orhanli-Tuzla, 34956 Istanbul, Turkey.
| | - Paola Gamba
- Department of Clinical and Biological Sciences, University of Torino, Torino, Italy.
| | - Simona Gargiulo
- Department of Clinical and Biological Sciences, University of Torino, Torino, Italy.
| | - Gabriella Testa
- Department of Clinical and Biological Sciences, University of Torino, Torino, Italy.
| | - Erica Staurenghi
- Department of Clinical and Biological Sciences, University of Torino, Torino, Italy
| | - Gabriella Leonarduzzi
- Department of Clinical and Biological Sciences, University of Torino, Torino, Italy.
| | - Giuseppe Poli
- Department of Clinical and Biological Sciences, University of Torino, Torino, Italy.
| | - Huveyda Basaga
- Biological Sciences and Bioengineering Program, Faculty of Engineering and Natural Sciences, Sabanci University, Orhanli-Tuzla, 34956 Istanbul, Turkey.
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17
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Abstract
Alzheimer's disease (AD) is the most common cause of dementia with no cure at present. Cholesterol metabolism is closely associated with AD at several stages. ACAT1 converts free cholesterol to cholesteryl esters, and plays important roles in cellular cholesterol homeostasis. Recent studies show that in a mouse model, blocking ACAT1 provides multiple beneficial effects on AD. Here we review the current evidence that implicates ACAT1 as a therapeutic target for AD. We also discuss the potential usage of various ACAT inhibitors currently available to treat AD.
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18
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Graham A. Mitochondrial regulation of macrophage cholesterol homeostasis. Free Radic Biol Med 2015; 89:982-92. [PMID: 26416507 DOI: 10.1016/j.freeradbiomed.2015.08.010] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 07/28/2015] [Accepted: 08/11/2015] [Indexed: 12/19/2022]
Abstract
This review explores the relationship between mitochondrial structure and function in the regulation of macrophage cholesterol metabolism and proposes that mitochondrial dysfunction contributes to loss of the elegant homeostatic mechanisms which normally maintain cellular sterol levels within defined limits. Mitochondrial sterol 27-hydroxylase (CYP27A1) can generate oxysterol activators of liver X receptors which heterodimerise with retinoid X receptors, enhancing the transcription of ATP binding cassette transporters (ABCA1, ABCG1, and ABCG4), that can remove excess cholesterol via efflux to apolipoproteins A-1, E, and high density lipoprotein, and inhibit inflammation. The activity of CYP27A1 is regulated by the rate of supply of cholesterol substrate to the inner mitochondrial membrane, mediated by a complex of proteins. The precise identity of this dynamic complex remains controversial, even in steroidogenic tissues, but may include steroidogenic acute regulatory protein and the 18 kDa translocator protein, together with voltage-dependent anion channels, ATPase AAA domain containing protein 3A, and optic atrophy type 1 proteins. Certainly, overexpression of StAR and TSPO proteins can enhance macrophage cholesterol efflux to apoA-I and/or HDL, while perturbations in mitochondrial function, or changes in the expression of mitochondrial fusion proteins, alter the efficiency of cholesterol efflux. Molecules which can sustain or improve mitochondrial function or increase the activity of the protein complex involved in cholesterol transfer may have utility in resolving the problem of dysregulated macrophage cholesterol homeostasis, a condition which may contribute to inflammation, atherosclerosis, nonalcoholic steatohepatitis, osteoblastic bone resorption, and some disorders of the central nervous system.
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Affiliation(s)
- Annette Graham
- Department of Life Sciences, School of Health and Life Sciences, and Institute for Applied Health Research, Glasgow Caledonian University, 70 Cowcaddens Road, Glasgow G4 0BA, United Kingdom.
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19
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Vurusaner B, Gamba P, Testa G, Gargiulo S, Biasi F, Zerbinati C, Iuliano L, Leonarduzzi G, Basaga H, Poli G. Survival signaling elicited by 27-hydroxycholesterol through the combined modulation of cellular redox state and ERK/Akt phosphorylation. Free Radic Biol Med 2014; 77:376-85. [PMID: 25110320 DOI: 10.1016/j.freeradbiomed.2014.07.026] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 07/08/2014] [Accepted: 07/21/2014] [Indexed: 01/16/2023]
Abstract
The oxysterol 27-hydroxycholesterol (27-OH) is increasingly considered to be involved in a variety of pathophysiological processes, having been shown to modulate cell proliferation and metabolism, and also to exert proinflammatory and proapoptotic effects. This study aimed to elucidate the molecular pathways whereby 27-OH may generate survival signals in cells of the macrophage lineage, and to clarify whether its known prooxidant effect is involved in that process. A net up-regulation of survival signaling, involving the extracellular signal-regulated kinase (ERK) and phosphoinositide 3-kinase (PI3K)/Akt phosphorylation pathways, was observed in U937 promonocytic cells cultivated over time in the presence of a low micromolar concentration of the oxysterol. Interestingly, the up-regulation of both kinases was shown to be closely dependent on an early 27-OH-induced intracellular increase of reactive oxygen species (ROS). In turn, stimulation of ERK and PI3K/Akt both significantly quenched ROS steady state and markedly phosphorylated Bad, thereby determining a marked delay of the oxysterol׳s proapoptotic action. The 27-OH-induced survival pathways thus appear to be redox modulated and, if they occur within or nearby inflammatory cells during progression of chronic diseases such as cancer and atherosclerosis, they could significantly impact the growth and evolution of such diseases.
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Affiliation(s)
- Beyza Vurusaner
- Biological Sciences and Bioengineering Program, Faculty of Engineering and Natural Sciences, Sabanci University, Orhanli-Tuzla, 34956 Istanbul, Turkey.
| | - Paola Gamba
- Department of Clinical and Biological Sciences, University of Turin, Turin, Italy.
| | - Gabriella Testa
- Department of Clinical and Biological Sciences, University of Turin, Turin, Italy.
| | - Simona Gargiulo
- Department of Clinical and Biological Sciences, University of Turin, Turin, Italy.
| | - Fiorella Biasi
- Department of Clinical and Biological Sciences, University of Turin, Turin, Italy.
| | - Chiara Zerbinati
- Department of Medical-Surgical Sciences and Biotechnology, Vascular Biology and Mass Spectrometry Laboratory, Sapienza University of Rome, Latina, Italy.
| | - Luigi Iuliano
- Department of Medical-Surgical Sciences and Biotechnology, Vascular Biology and Mass Spectrometry Laboratory, Sapienza University of Rome, Latina, Italy.
| | | | - Huveyda Basaga
- Biological Sciences and Bioengineering Program, Faculty of Engineering and Natural Sciences, Sabanci University, Orhanli-Tuzla, 34956 Istanbul, Turkey.
| | - Giuseppe Poli
- Department of Clinical and Biological Sciences, University of Turin, Turin, Italy.
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20
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Oxysterols are agonist ligands of RORγt and drive Th17 cell differentiation. Proc Natl Acad Sci U S A 2014; 111:12163-8. [PMID: 25092323 DOI: 10.1073/pnas.1322807111] [Citation(s) in RCA: 192] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The RAR-related orphan receptor gamma t (RORγt) is a nuclear receptor required for generating IL-17-producing CD4(+) Th17 T cells, which are essential in host defense and may play key pathogenic roles in autoimmune diseases. Oxysterols elicit profound effects on immune and inflammatory responses as well as on cholesterol and lipid metabolism. Here, we describe the identification of several naturally occurring oxysterols as RORγt agonists. The most potent and selective activator for RORγt is 7β, 27-dihydroxycholesterol (7β, 27-OHC). We show that these oxysterols reverse the inhibitory effect of an RORγt antagonist, ursolic acid, in RORγ- or RORγt-dependent cell-based reporter assays. These ligands bind directly to recombinant RORγ ligand binding domain (LBD), promote recruitment of a coactivator peptide, and reduce binding of a corepressor peptide to RORγ LBD. In primary cells, 7β, 27-OHC and 7α, 27-OHC enhance the differentiation of murine and human IL-17-producing Th17 cells in an RORγt-dependent manner. Importantly, we showed that Th17, but not Th1 cells, preferentially produce these two oxysterols. In vivo, administration of 7β, 27-OHC in mice enhanced IL-17 production. Mice deficient in CYP27A1, a key enzyme in generating these oxysterols, showed significant reduction of IL-17-producing cells, including CD4(+) and γδ(+) T cells, similar to the deficiency observed in RORγt knockout mice. Our results reveal a previously unknown mechanism for selected oxysterols as immune modulators and a direct role for CYP27A1 in generating these RORγt agonist ligands, which we propose as RORγt endogenous ligands, driving both innate and adaptive IL-17-dependent immune responses.
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21
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Tempel W, Grabovec I, MacKenzie F, Dichenko YV, Usanov SA, Gilep AA, Park HW, Strushkevich N. Structural characterization of human cholesterol 7α-hydroxylase. J Lipid Res 2014; 55:1925-32. [PMID: 24927729 DOI: 10.1194/jlr.m050765] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Hepatic conversion to bile acids is a major elimination route for cholesterol in mammals. CYP7A1 catalyzes the first and rate-limiting step in classic bile acid biosynthesis, converting cholesterol to 7α-hydroxycholesterol. To identify the structural determinants that govern the stereospecific hydroxylation of cholesterol, we solved the crystal structure of CYP7A1 in the ligand-free state. The structure-based mutation T104L in the B' helix, corresponding to the nonpolar residue of CYP7B1, was used to obtain crystals of complexes with cholest-4-en-3-one and with cholesterol oxidation product 7-ketocholesterol (7KCh). The structures reveal a motif of residues that promote cholest-4-en-3-one binding parallel to the heme, thus positioning the C7 atom for hydroxylation. Additional regions of the binding cavity (most distant from the access channel) are involved to accommodate the elongated conformation of the aliphatic side chain. Structural complex with 7KCh shows an active site rigidity and provides an explanation for its inhibitory effect. Based on our previously published data, we proposed a model of cholesterol abstraction from the membrane by CYP7A1 for metabolism. CYP7A1 structural data provide a molecular basis for understanding of the diversity of 7α-hydroxylases, on the one hand, and cholesterol-metabolizing enzymes adapted for their specific activity, on the other hand.
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Affiliation(s)
- Wolfram Tempel
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, M5G 1L7, Canada
| | - Irina Grabovec
- Institute of Bioorganic Chemistry NAS of Belarus, Minsk, 220141 Belarus
| | - Farrell MacKenzie
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, M5G 1L7, Canada
| | | | - Sergey A Usanov
- Institute of Bioorganic Chemistry NAS of Belarus, Minsk, 220141 Belarus
| | - Andrei A Gilep
- Institute of Bioorganic Chemistry NAS of Belarus, Minsk, 220141 Belarus
| | - Hee-Won Park
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, LA 70112
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22
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Helmschrodt C, Becker S, Thiery J, Ceglarek U. Preanalytical standardization for reactive oxygen species derived oxysterol analysis in human plasma by liquid chromatography–tandem mass spectrometry. Biochem Biophys Res Commun 2014; 446:726-30. [DOI: 10.1016/j.bbrc.2013.12.087] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Accepted: 12/17/2013] [Indexed: 01/09/2023]
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23
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The Influence of an Obesogenic Diet on Oxysterol Metabolism in C57BL/6J Mice. CHOLESTEROL 2014; 2014:843468. [PMID: 24672716 PMCID: PMC3941159 DOI: 10.1155/2014/843468] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2013] [Revised: 12/18/2013] [Accepted: 12/21/2013] [Indexed: 11/18/2022]
Abstract
Our current understanding of oxysterol metabolism during different disease states such as obesity and dyslipidemia is limited. Therefore, the aim of this study was to determine the effect of diet-induced obesity on the tissue distribution of various oxysterols and the mRNA expression of key enzymes involved in oxysterol metabolism. To induce obesity, male C57BL/6J mice were fed a high fat-cholesterol diet for 24 weeks. Following diet-induced obesity, plasma levels of 4β-hydroxycholesterol, 5,6α-epoxycholesterol, 5,6β-epoxycholesterol, 7α-hydroxycholesterol, 7β-hydroxycholesterol, and 27-hydroxycholesterol were significantly (P < 0.05) increased. In the liver and adipose tissue of the obese mice, 4β-hydroxycholesterol was significantly (P < 0.05) increased, whereas 27-hydroxycholesterol was increased only in the adipose tissue. No significant changes in either hepatic or adipose tissue mRNA expression were observed for oxysterol synthesizing enzymes 4β-hydroxylase, 27-hydroxylase, or 7α-hydroxylase. Hepatic mRNA expression of SULT2B1b, a key enzyme involved in oxysterol detoxification, was significantly (P < 0.05) elevated in the obese mice. Interestingly, the appearance of the large HDL1 lipoprotein was observed with increased oxysterol synthesis during obesity. In diet-induced obese mice, dietary intake and endogenous enzymatic synthesis of oxysterols could not account for the increased oxysterol levels, suggesting that nonenzymatic cholesterol oxidation pathways may be responsible for the changes in oxysterol metabolism.
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24
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van Reyk DM, Brown AJ, Hult'en LM, Dean RT, Jessup W. Oxysterols in biological systems: sources, metabolism and pathophysiological relevance. Redox Rep 2013; 11:255-62. [PMID: 17207307 DOI: 10.1179/135100006x155003] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Oxysterols are the 27-carbon products of cholesterol oxidation by both enzymic and non-enzymic mechanisms. Their roles in cholesterol homeostasis, as well as in diseases in which oxidative damage and lipid peroxidation are implicated (e.g. atherosclerosis), have been investigated extensively. However, there are a number of important considerations regarding the physiological/pathophysiological functions and activities of the different oxysterols. First, in both normal and diseased tissues, the levels of oxysterols are very low when compared to the native sterol. Also, when assessing studies that have measured the levels of oxysterols in biological samples, there must be careful consideration as to the method of sample isolation, storage and sampling. This is because of the potential generation or loss of oxysterols during these procedures. Additionally, the relevance of in vitro studies which examine the effects of oxysterols upon cell function should be judged as to cellular oxysterol content (both in terms of the levels of oxysterol and the degree of esterification) resulting from the oxysterol treatment. We present evidence that the means by which oxysterol is delivered in vitro determines whether the oxysterol content reflects what has been found in vivo. Studies identifying the specific cellular targets of oxysterol indicate that several oxysterols may be regulators of cellular lipid metabolism via control of gene transcription.
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Affiliation(s)
- David M van Reyk
- Department of Medical and Molecular Biosciences, University of Technology, Sydney, Australia.
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Abstract
Cholesterol trafficking from the outer to the cholesterol-poor inner mitochondrial membrane requires energized, polarized and actively respiring mitochondria, mediated by a highly regulated multimeric (140-200 kDa) protein complex comprising StAR (steroidogenic acute regulatory protein), mitochondrial TSPO (translocator protein), VDAC (voltage-dependent anion channel), ANT (adenine nucleotide transporter) and associated regulatory proteins. Mitochondrial cholesterol transport is rate-limiting in the CYP27A1 (sterol 27-hydroxylase)-dependent generation of oxysterol ligands for LXR (liver X receptor) transcription factors that regulate the expression of genes encoding proteins in the cholesterol efflux pathway, such as ABC transporters (ATP-binding cassette transporters) ABCA1 and ABCG1. These transporters transfer cholesterol and/or phospholipids across the plasma membrane to (apo)lipoprotein acceptors, generating nascent HDLs (high-density lipoproteins), which can safely transport excess cholesterol through the bloodstream to the liver for excretion in bile. Utilizing information from steroidogenic tissues, we propose that perturbations in mitochondrial function may reduce the efficiency of the cholesterol efflux pathway, favouring accumulation of cholesteryl ester 'foam cells' and allowing the toxic accumulation of free cholesterol at the interface between the endoplasmic reticulum and the mitochondrial membrane. In turn, this will trigger opening of the permeability transition pore, allowing unregulated production of oxysterols via CYP27A1, allowing the accumulation of esterified forms of this oxysterol within human atherosclerotic lesions. Defective cholesterol efflux also induces endoplasmic reticulum stress, proteasomal degradation of ABCA1 and Fas-dependent apoptosis, replicating findings in macrophages in advanced atherosclerotic lesions. Small molecules targeted to mitochondria, capable of sustaining mitochondrial function or improving cholesterol trafficking may aid cholesterol efflux from macrophage 'foam' cells, regressing and stabilizing the atherosclerotic plaque.
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Charvet CD, Laird J, Xu Y, Salomon RG, Pikuleva IA. Posttranslational modification by an isolevuglandin diminishes activity of the mitochondrial cytochrome P450 27A1. J Lipid Res 2013; 54:1421-9. [PMID: 23479405 DOI: 10.1194/jlr.m035790] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Posttranslational modification by isolevuglandins (isoLGs), arachidonate oxidation products, is an important yet understudied process associated with altered protein properties. This type of modification is detected in cytochrome P450 27A1 (CYP27A1), a multifunction enzyme expressed in almost every cell and involved in the metabolism of cholesterol and other sterols. Previously, the CYP27A1 Lys(358)-isoLG adduct was found in human retina afflicted with age-related macular degeneration. Yet, the effect of Lys(358) modification on enzyme activity was not investigated. Herein, we characterized catalytic properties of Lys(358) as well as Lys(476) CYP27A1 mutants before and after isoLG treatment and quantified the extent of modification by multiple reaction monitoring. The K358R mutant was less susceptible to isoLG-induced loss of catalytic activity than the wild type (WT), whereas the K476R mutant was nearly as vulnerable as the WT. Both mutants showed less isoLG modification than WT. Thus, modification of Lys(358), a residue involved in redox partner interactions, is the major contributor to isoLG-associated loss of CYP27A1 activity. Our data show the specificity of isoLG modification, provide direct evidence that isoLG adduction impairs enzyme activity, and support our hypothesis that isoLG modification in the retina is detrimental to CYP27A1 enzyme activity, potentially disrupting cholesterol homeostasis.
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Affiliation(s)
- Casey D Charvet
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH 44106, USA
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Interrelationship between ATP-binding cassette transporters and oxysterols. Biochem Pharmacol 2013; 86:80-8. [PMID: 23500544 DOI: 10.1016/j.bcp.2013.02.033] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 02/27/2013] [Accepted: 02/27/2013] [Indexed: 12/11/2022]
Abstract
ATP-binding cassette (ABC) transporters constitute a ubiquitous superfamily of membrane proteins responsible for the translocation of several substances across membranes using the chemical energy provided by ATP hydrolysis. ABC transporters participate in many physiological and pathophysiological processes, including cholesterol and lipid transportation and multidrug resistance. Oxysterols are the products of cholesterol oxidation, formed by both enzymatic and non-enzymatic mechanisms. The role of oxysterols in cholesterol metabolism and several diseases has been widely investigated, but many questions remain to be answered. Several lines of evidence link ABC transporter functions with cholesterol and oxysterol metabolism. This review discusses ABC transporters, oxysterols, and how they interact with each other.
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Brown AJ. Cholesterol versus other sterols: How do they compare as physiological regulators of cholesterol homeostasis? EUR J LIPID SCI TECH 2012. [DOI: 10.1002/ejlt.201100295] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Andrew J. Brown
- BABS, School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia
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Charvet C, Liao WL, Heo GY, Laird J, Salomon RG, Turko IV, Pikuleva IA. Isolevuglandins and mitochondrial enzymes in the retina: mass spectrometry detection of post-translational modification of sterol-metabolizing CYP27A1. J Biol Chem 2011; 286:20413-22. [PMID: 21498512 PMCID: PMC3121529 DOI: 10.1074/jbc.m111.232546] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 04/04/2011] [Indexed: 11/06/2022] Open
Abstract
We report the first peptide mapping and sequencing of an in vivo isolevuglandin-modified protein. Mitochondrial cytochrome P450 27A1 (CYP27A1) is a ubiquitous multifunctional sterol C27-hydroxylase that eliminates cholesterol and likely 7-ketocholesterol from the retina and many other tissues. We investigated the post-translational modification of this protein with isolevuglandins, arachidonate oxidation products. Treatment of purified recombinant CYP27A1 with authentic iso[4]levuglandin E(2) (iso[4]LGE(2)) in vitro diminished enzyme activity in a time- and phospholipid-dependent manner. A multiple reaction monitoring protocol was then developed to identify the sites and extent of iso[4]LGE(2) adduction. CYP27A1 exhibited only three Lys residues, Lys(134), Lys(358), and Lys(476), that readily interact with iso[4]LGE(2) in vitro. Such selective modification enabled the generation of an internal standard, (15)N-labeled CYP27A1 modified with iso[4]LGE(2), for the subsequent analysis of a human retinal sample. Two multiple reaction monitoring transitions arising from the peptide AVLK(358)(-C(20)H(26)O(3))ETLR in the retinal sample were observed that co-eluted with the corresponding two (15)N transitions from the supplemented standard. These data demonstrate that modified CYP27A1 is present in the retina. We suggest that such protein modification impairs sterol elimination and likely has other pathological sequelae. We also propose that the post-translational modifications identified in CYP27A1 exemplify a general mechanism whereby oxidative stress and inflammation deleteriously affect protein function, contributing, for example, to cholesterol-rich lesions associated with age-related macular degeneration and cardiovascular disease. The proteomic protocols developed in this study are generally applicable to characterization of lipid-derived oxidative protein modifications occurring in vivo, including proteins bound to membranes.
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Affiliation(s)
- Casey Charvet
- From the Departments of Ophthalmology and Visual Sciences and
| | - Wei-Li Liao
- the Institute for Bioscience and Biotechnology Research, Rockville, Maryland 20850, and
| | - Gun-Young Heo
- From the Departments of Ophthalmology and Visual Sciences and
| | - James Laird
- Chemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | | | - Illarion V. Turko
- the Institute for Bioscience and Biotechnology Research, Rockville, Maryland 20850, and
- the Analytical Chemistry Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899
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Heo GY, Bederman I, Mast N, Liao WL, Turko IV, Pikuleva IA. Conversion of 7-ketocholesterol to oxysterol metabolites by recombinant CYP27A1 and retinal pigment epithelial cells. J Lipid Res 2011; 52:1117-1127. [PMID: 21411718 DOI: 10.1194/jlr.m014217] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Of the different oxygenated cholesterol metabolites, 7-ketocholesterol (7KCh) is considered a noxious oxy-sterol implicated in the development of certain pathologies, including those found in the eye. Here we elucidated whether sterol 27-hydroxylase cytochrome P450 27A1 (CYP27A1) is involved in elimination of 7KCh from the posterior part of the eye: the neural retina and underlying retinal pigment epithelium (RPE). We first established that the affinities of purified recombinant CYP27A1 for 7KCh and its endogenous substrate cholesterol are similar, yet 7KCh is metabolized at a 4-fold higher rate than cholesterol in the reconstituted system in vitro. Lipid extracts from bovine neural retina and RPE were then analyzed by isotope dilution GC-MS for the presence of the 7KCh-derived oxysterols. Two metabolites, 3β,27-dihydroxy-5-cholesten-7-one (7KCh-27OH) and 3β-hydroxy-5-cholesten-7-one-26-oic acid (7KCh-27COOH), were detected in the RPE but not in the neural retina. 7KCh-27OH was also formed when RPE homogenates were supplemented with NADPH and the mitochondrial redox system. Quantifications in human RPE showed that CYP27A1 is indeed expressed in the RPE at 2-4-fold higher levels than in the neural retina. The data obtained represent evidence for the role of CYP27A1 in retinal metabolism of 7KCh and suggest that, in addition to cholesterol removal, the functions of this enzyme could also include elimination of toxic endogenous compounds.
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Affiliation(s)
- Gun-Young Heo
- Departments of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH
| | - Ilya Bederman
- Pediatrics, Case Western Reserve University, Cleveland, OH
| | - Natalia Mast
- Departments of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH
| | - Wei-Li Liao
- Institute for Bioscience and Biotechnology Research, Rockville, MD
| | - Illarion V Turko
- Institute for Bioscience and Biotechnology Research, Rockville, MD; Division Analytical Chemistry, National Institute of Standards and Technology, Gaithersburg, MD
| | - Irina A Pikuleva
- Departments of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH.
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Zhao Y, Van Berkel TJ, Van Eck M. Relative roles of various efflux pathways in net cholesterol efflux from macrophage foam cells in atherosclerotic lesions. Curr Opin Lipidol 2010; 21:441-53. [PMID: 20683325 DOI: 10.1097/mol.0b013e32833dedaa] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW Cholesterol efflux mechanisms are essential for macrophage cholesterol homeostasis. HDL, an important cholesterol efflux acceptor, comprises a class of heterogeneous particles that induce cholesterol efflux via distinct pathways. This review focuses on the understanding of the different cholesterol efflux pathways and physiological acceptors involved, and their regulation in atherosclerotic lesions. RECENT FINDINGS The synergistic interactions of ATP-binding cassette transporters A1 and G1 as well as ATP-binding cassette transporter A1 and scavenger receptor class B type I are essential for cellular cholesterol efflux and the prevention of macrophage foam cell formation. However, the importance of aqueous diffusion should also not be underestimated. Significant progress has been made in understanding the mechanisms underlying ATP-binding cassette A1-mediated cholesterol efflux and regulation of its expression and trafficking. Conditions locally in the atherosclerotic lesion, for example, lipids, cytokines, oxidative stress, and hypoxia, as well as systemic factors, including inflammation and diabetes, critically influence the expression of cholesterol transporters on macrophage foam cells. Furthermore, HDL modification and remodeling in atherosclerosis, inflammation, and diabetes impairs its function as an acceptor for cellular cholesterol. SUMMARY Recent advances in the understanding of the regulation of cholesterol transporters and their acceptors in atherosclerotic lesions indicate that HDL-based therapies should aim to enhance the activity of cholesterol transporters and improve both the quantity and quality of HDL.
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Affiliation(s)
- Ying Zhao
- Division of Biopharmaceutics, Leiden/Amsterdam Center for Drug Research, University of Leiden, Leiden, The Netherlands
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Rodríguez IR, Larrayoz IM. Cholesterol oxidation in the retina: implications of 7KCh formation in chronic inflammation and age-related macular degeneration. J Lipid Res 2010; 51:2847-62. [PMID: 20567027 DOI: 10.1194/jlr.r004820] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
This review will discuss the formation and potential implications of 7-ketocholesterol (7KCh) in the retina. 7KCh is a proinflammatory oxysterol known to be present in high amounts in oxidized LDL deposits associated with atheromatous plaques. 7KCh is generated in situ in these lipoprotein deposits where it can accumulate and reach very high concentrations. In normal primate retina, 7KCh has been found associated with lipoprotein deposits in the choriocapillaris, Bruch's membrane, and the retinal pigment epithelium (RPE). In photodamaged rats, 7KCh has been found in the neural retina in areas of high mitochondrial content, ganglion cells, photoreceptor inner segments and synapses, and the RPE. Intermediates found by LCMS indicate 7KCh is formed via a free radical-mediated mechanism catalyzed by iron. 7KCh seems to activate several kinase signaling pathways that work via nuclear factor κB and cause the induction of vascular endothelial growth factor, interleukin (IL)-6, and IL-8. There seems to be little evidence of 7KCh metabolism in the retina, although some form of efflux mechanism may be active. The chronic mode of formation and the potent inflammatory properties of 7KCh indicate it may be an "age-related" risk factor in aging diseases such as atherosclerosis, Alzheimer's, and age-related macular degeneration.
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Affiliation(s)
- Ignacio R Rodríguez
- Mechanisms of Retinal Diseases Section, Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, Bethesda, MD 20892, USA.
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Larrayoz IM, Huang JD, Lee JW, Pascual I, Rodríguez IR. 7-ketocholesterol-induced inflammation: involvement of multiple kinase signaling pathways via NFκB but independently of reactive oxygen species formation. Invest Ophthalmol Vis Sci 2010; 51:4942-55. [PMID: 20554621 DOI: 10.1167/iovs.09-4854] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE 7-Ketocholesterol (7KCh) accumulates in oxidized lipoprotein deposits and is known to be involved in macrophage foam cell formation and atherosclerosis. 7-KCh is present in the primate retina and is associated with oxidized lipoprotein deposits located in the choriocapillaris, Bruch's membrane, and retinal pigment epithelium (RPE). 7-KCh can also be formed in the retina as a consequence of light-induced iron release. The purpose of this study was to examine the signaling pathways involved in the 7KCh-mediated inflammatory response focusing on three cytokines, VEGF, IL-6, and IL-8. METHODS ARPE-19 cells were treated with 7KCh solubilized in hydroxypropyl-β-cyclodextrin. Cytokines were quantified by qRT-PCR (mRNA) and ELISA (protein) using commercially available products. NFκB activation was determined by IκBα mRNA induction. RESULTS Treatment of ARPE-19 cells with 15 μM 7KCh markedly induced the expression of VEGF, IL-6, and IL-8. No increase in NOX-4 expression or ROS formation was detected. 7KCh induced the phosphorylation of ERK1/2 and p38MAPK, and inhibitors to these kinases markedly reduced the cytokine expression but did not affect the IκBα mRNA expression. By contrast, inhibition of PI3K and PKCζ significantly decreased the cytokine and IκBα mRNA expression. Inhibition of the IκB kinase complex essentially ablated all cytokine induction. CONCLUSIONS 7KCh induces cytokines via three kinase signaling pathways, AKT-PKCζ-NFκB, p38 MAPK, and ERK. The MAPK/ERK pathways seem to preferentially enhance cytokine induction downstream from NFκB activation. The results of this study suggest that 7KCh activates these pathways through interactions in the plasma membrane, but the mechanism(s) remains unknown.
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Affiliation(s)
- Ignacio M Larrayoz
- Mechanisms of Retinal Diseases Section, Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
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Chang TY, Chang CCY, Bryleva E, Rogers MA, Murphy SR. Neuronal cholesterol esterification by ACAT1 in Alzheimer's disease. IUBMB Life 2010; 62:261-7. [PMID: 20101629 DOI: 10.1002/iub.305] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Cholesterol has been implicated in various neurodegenerative diseases. Here we review the connection between cholesterol and Alzheimer's disease (AD), focusing on a recent study that links neuronal cholesterol esterification with biosynthesis of 24(S)-hydroxycholesterol and the fate of human amyloid precursor protein in a mouse model of AD. We also briefly evaluate the potential of ACAT1 as a drug target for AD.
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Affiliation(s)
- Ta-Yuan Chang
- Department of Biochemistry, Dartmouth Medical School, Hanover, NH 03755, USA.
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Taylor JM, Borthwick F, Bartholomew C, Graham A. Overexpression of steroidogenic acute regulatory protein increases macrophage cholesterol efflux to apolipoprotein AI. Cardiovasc Res 2010; 86:526-34. [DOI: 10.1093/cvr/cvq015] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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Mathieu JM, Schloendorn J, Rittmann BE, Alvarez PJJ. Medical bioremediation of age-related diseases. Microb Cell Fact 2009; 8:21. [PMID: 19358742 PMCID: PMC2674406 DOI: 10.1186/1475-2859-8-21] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2009] [Accepted: 04/09/2009] [Indexed: 12/12/2022] Open
Abstract
Catabolic insufficiency in humans leads to the gradual accumulation of a number of pathogenic compounds associated with age-related diseases, including atherosclerosis, Alzheimer's disease, and macular degeneration. Removal of these compounds is a widely researched therapeutic option, but the use of antibodies and endogenous human enzymes has failed to produce effective treatments, and may pose risks to cellular homeostasis. Another alternative is "medical bioremediation," the use of microbial enzymes to augment missing catabolic functions. The microbial genetic diversity in most natural environments provides a resource that can be mined for enzymes capable of degrading just about any energy-rich organic compound. This review discusses targets for biodegradation, the identification of candidate microbial enzymes, and enzyme-delivery methods.
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Affiliation(s)
- Jacques M Mathieu
- Dept. of Civil and Environmental Engineering, Rice University, Houston, TX, USA
| | - John Schloendorn
- Dept. of Civil and Environmental Engineering, Arizona State University, Tempe, AZ, USA
| | - Bruce E Rittmann
- Dept. of Civil and Environmental Engineering, Arizona State University, Tempe, AZ, USA
| | - Pedro JJ Alvarez
- Dept. of Civil and Environmental Engineering, Rice University, Houston, TX, USA
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Balázs Z, Nashev LG, Chandsawangbhuwana C, Baker ME, Odermatt A. Hexose-6-phosphate dehydrogenase modulates the effect of inhibitors and alternative substrates of 11beta-hydroxysteroid dehydrogenase 1. Mol Cell Endocrinol 2009; 301:117-22. [PMID: 19010388 DOI: 10.1016/j.mce.2008.10.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Revised: 10/09/2008] [Accepted: 10/09/2008] [Indexed: 11/23/2022]
Abstract
Intracellular glucocorticoid reactivation is catalyzed by 11beta-hydroxysteroid dehydrogenase 1 (11beta-HSD1), which functions predominantly as a reductase in cells expressing hexose-6-phosphate dehydrogenase (H6PDH). We recently showed that the ratios of cortisone to cortisol and 7-keto- to 7-hydroxy-neurosteroids are regulated by 11beta-HSD1 and very much depend on coexpression with H6PDH, providing cosubstrate NADPH. Here, we investigated the impact of H6PDH on the modulation of 11beta-HSD1-dependent interconversion of cortisone and cortisol by inhibitors and alternative substrates. Using HEK-293 cells expressing 11beta-HSD1 or coexpressing 11beta-HSD1 and H6PDH, we observed significant differences of 11beta-HSD1 inhibition by natural and pharmaceutical compounds as well as endogenous hormone metabolites. Furthermore, we show potent and dose-dependent inhibition of 11beta-HSD1 by 7-keto-DHEA in differentiated human THP-1 macrophages and in HEK-293 cells overexpressing 11beta-HSD1 with or without H6PDH. In contrast, 7-ketocholesterol (7-KC) did not inhibit 11beta-HSD1 in HEK-293 cells, even in the presence of H6PDH, but inhibited 11beta-HSD1 reductase activity in differentiated THP-1 macrophages (IC(50) 8.1+/-0.9microM). 7-Keto-DHEA but not 7-KC inhibited 11beta-HSD1 in HEK-293 cell lysates. In conclusion, cellular factors such as H6PDH can significantly modulate the effect of inhibitors and alternative 7-oxygenated substrates on intracellular glucocorticoid availability.
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Affiliation(s)
- Zoltán Balázs
- Division of Molecular and Systems Toxicology, Department of Pharmaceutical Sciences, University of Basel, Klingelbergstrasse 50, CH-4056 Basel, Switzerland
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Hadoke PWF, Iqbal J, Walker BR. Therapeutic manipulation of glucocorticoid metabolism in cardiovascular disease. Br J Pharmacol 2009; 156:689-712. [PMID: 19239478 DOI: 10.1111/j.1476-5381.2008.00047.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The therapeutic potential for manipulation of glucocorticoid metabolism in cardiovascular disease was revolutionized by the recognition that access of glucocorticoids to their receptors is regulated in a tissue-specific manner by the isozymes of 11beta-hydroxysteroid dehydrogenase. Selective inhibitors of 11beta-hydroxysteroid dehydrogenase type 1 have been shown recently to ameliorate cardiovascular risk factors and inhibit the development of atherosclerosis. This article addresses the possibility that inhibition of 11beta-hydroxsteroid dehydrogenase type 1 activity in cells of the cardiovascular system contributes to this beneficial action. The link between glucocorticoids and cardiovascular disease is complex as glucocorticoid excess is linked with increased cardiovascular events but glucocorticoid administration can reduce atherogenesis and restenosis in animal models. There is considerable evidence that glucocorticoids can interact directly with cells of the cardiovascular system to alter their function and structure and the inflammatory response to injury. These actions may be regulated by glucocorticoid and/or mineralocorticoid receptors but are also dependent on the 11beta-hydroxysteroid dehydrogenases which may be expressed in cardiac, vascular (endothelial, smooth muscle) and inflammatory (macrophages, neutrophils) cells. The activity of 11beta-hydroxysteroid dehydrogenases in these cells is dependent upon differentiation state, the action of pro-inflammaotory cytokines and the influence of endogenous inhibitors (oxysterols, bile acids). Further investigations are required to clarify the link between glucocorticoid excess and cardiovascular events and to determine the mechanism through which glucocorticoid treatment inhibits atherosclerosis/restenosis. This will provide greater insights into the potential benefit of selective 11beta-hydroxysteroid dehydrogenase inhibitors in treatment of cardiovascular disease.
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Affiliation(s)
- Patrick W F Hadoke
- Centre for Cardiovascular Sciences, University of Edinburgh, The Queen's Medical Research Institute, Edinburgh, UK.
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Javitt NB. Oxysterols: novel biologic roles for the 21st century. Steroids 2008; 73:149-57. [PMID: 18068744 DOI: 10.1016/j.steroids.2007.10.004] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2007] [Revised: 09/17/2007] [Accepted: 10/12/2007] [Indexed: 01/17/2023]
Abstract
A major focus for the 21st century are the sterol intermediates in cholesterol synthesis and their metabolites. No longer considered inactive way stations in their transformation to cholesterol, both physiologic and pathophysiologic studies, though early in their development, indicate novel biologic roles for these sterols, and their oxysterol metabolites that bypass cholesterol, the expected end product. A major impetus for further inquiry is the recognition that in genetically determined errors in cholesterol synthesis such as Smith-Lemil-Opitz syndrome, the phenotypic effects on the developing fetus are not solely attributable to the lack of cholesterol but the accumulation of 7-dehydrocholesterol and its 27-hydroxy metabolite. This view is now supported by a new mouse model, the double knockout Insig1 & 2 (insulin-induced genes 1 & 2) in which lack of the protein product results in a greater production of lanosterol compared to cholesterol during fetal life with severe dysmorphic consequences. Further support can be derived from in vitro studies of the Sonic hedgehog signaling pathway, essential for normal morphogenesis in the central nervous system and perhaps other organs, which may require the local presence of oxysterols for full expression. Future studies that can delineate the specific role of a sterol intermediate or its metabolite require a paradigm shift away from the generic use of oxysterols as a class of compounds to a focus on specific sterols that can be expected in tissues and techniques for mimicking the local environment. Another class of oxysterols are those arising by photoxidation, now considered to be an expected event generated by the photons of visible blue light and therefore pari passu with normal vision. The sequence of events from peroxides of cholesterol to hydroxy and keto derivatives is the signature of singlet oxygen as opposed to free radicals and other mechanisms for generating reactive oxygen species. Perhaps surprisingly, the retina expresses CYP 27A1 and CYP 46A1, enzymes with broad substrate specificity for ring-modified sterols, implying that, in addition to a rich blood supply for disposing of potentially toxic oxysterols, they can be detoxified locally. Recognition that the retina has nuclear receptors similar to those found in other tissues raises the possibility that the sterols that are generated may function in their traditional role as ligands for modulating gene expression but other, nonligand, activities can be expected since other proteins such as the oxysterol-binding proteins exist and are considered to have biologic activities. To critically evaluate these potentially new biologic roles for oxysterols a need exists for the synthesis and utilization of the expected naturally occurring metabolites rather than available surrogates that may not be truly representative of their tissue effects and to utilize analytical techniques that can identify their existence at the expected concentrations in tissues.
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Affiliation(s)
- Norman B Javitt
- Department of Pediatrics and Medicine, NYU School of Medicine, 550 First Avenue, New York, NY 10016, United States.
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DuSell CD, Umetani M, Shaul PW, Mangelsdorf DJ, McDonnell DP. 27-hydroxycholesterol is an endogenous selective estrogen receptor modulator. Mol Endocrinol 2007; 22:65-77. [PMID: 17872378 PMCID: PMC2194632 DOI: 10.1210/me.2007-0383] [Citation(s) in RCA: 223] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Selective estrogen receptor (ER) modulators (SERMs) are ER ligands whose relative agonist/antagonist activities vary in a cell- and promoter-dependent manner. The molecular basis underlying this selectivity can be attributed to the ability of these ligands to induce distinct alterations in ER structure leading to differential recruitment of coactivators and corepressors. Whether SERM activity is restricted to synthetic ligands or whether molecules exist in vivo that function in an analogous manner remains unresolved. However, the recent observation that oxysterols bind ER and antagonize the actions of 17beta-estradiol (E2) on the vascular wall suggests that this class of ligands may possess SERM activity. We demonstrate here that 27-hydroxycholesterol (27HC), the most prevalent oxysterol in circulation, functions as a SERM, the efficacy of which varies when assessed on different endpoints. Importantly, 27HC positively regulates both gene transcription and cell proliferation in cellular models of breast cancer. Using combinatorial peptide phage display, we have determined that 27HC induces a unique conformational change in both ERalpha and ERbeta, distinguishing it from E2 and other SERMs. Thus, as with other ER ligands, it appears that the unique pharmacological activity of 27HC relates to its ability to impact ER structure and modulate cofactor recruitment. Cumulatively, these data indicate that 27HC is an endogenous SERM with partial agonist activity in breast cancer cells and suggest that it may influence the pathology of breast cancer. Moreover, given the product-precursor relationship between 27HC and cholesterol, our findings have implications with respect to breast cancer risk in obese/hypercholesteremic individuals.
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Affiliation(s)
- Carolyn D DuSell
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
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Larsson H, Böttiger Y, Iuliano L, Diczfalusy U. In vivo interconversion of 7beta-hydroxycholesterol and 7-ketocholesterol, potential surrogate markers for oxidative stress. Free Radic Biol Med 2007; 43:695-701. [PMID: 17664133 DOI: 10.1016/j.freeradbiomed.2007.04.033] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2007] [Revised: 04/16/2007] [Accepted: 04/28/2007] [Indexed: 11/16/2022]
Abstract
The oxysterols 7beta-hydroxycholesterol and 7-ketocholesterol are cholesterol autoxidation products. These two oxysterols are formed as a result of low density lipoprotein oxidation and in a study on biomarkers for oxidative stress in patients with atherosclerosis, 7beta-hydroxycholesterol was found to be the strongest predictor of progression of carotid atherosclerosis. Interconversion of 7beta-hydroxycholesterol and 7-ketocholesterol in vitro has been reported recently, using recombinant 11beta-hydroxysteroid dehydrogenase or rodent liver microsomes. In this study deuterium-labeled 7beta-hydroxycholesterol or 7-ketocholesterol was administered intravenously to two healthy volunteers and blood samples were collected at different time points. The mean half-life for elimination of 7beta-hydroxycholesterol from the circulation was estimated to be 1.9 h. The corresponding half-life for 7-ketocholesterol was estimated to be 1.5 h. Infusion of deuterium-labeled 7-ketocholesterol resulted in labeling of 7beta-hydroxycholesterol and vice versa. In addition, the biological within-day and between-day variations of the two oxysterols were determined. In summary, the present investigation clearly shows an interconversion of 7beta-hydroxycholesterol and 7-ketocholesterol in humans.
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Affiliation(s)
- Hanna Larsson
- Division of Clinical Chemistry, Department of Laboratory Medicine, Karolinska Institutet, Huddinge, SE-141 86 Stockholm, Sweden
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Fuda H, Javitt NB, Mitamura K, Ikegawa S, Strott CA. Oxysterols are substrates for cholesterol sulfotransferase. J Lipid Res 2007; 48:1343-52. [PMID: 17347498 DOI: 10.1194/jlr.m700018-jlr200] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Oxysterols constitute a class of cholesterol derivatives that exhibit broad biological effects ranging from cytotoxicity to regulation of nuclear receptors. The role of oxysterols such as 7-ketocholesterol (7-KC) in the development of retinal macular degeneration and atheromatous lesions is of particular interest, but little is known of their metabolic fate. We establish that the steroid/sterol sulfotransferase SULT2B1b, known to efficiently sulfonate cholesterol, also effectively sulfonates a variety of oxysterols, including 7-KC. The cytotoxic effect of 7-KC on 293T cells was attenuated when these cells, which do not express SULT2B1b, were transfected with SULT2B1b cDNA. Importantly, protection from 7-KC-induced loss of cell viability with transfection correlated with the synthesis of SULT2B1b protein and the production of the 7-KC sulfoconjugate (7-KCS). Moreover, when 7-KCS was added to the culture medium of 293T cells in amounts equimolar to 7-KC, no loss of cell viability occurred. Additionally, MCF-7 cells, which highly express SULT2B1b, were significantly more resistant to the cytotoxic effect of 7-KC. We extended the range of oxysterol substrates for SULT2B1b to include 7alpha/7beta-hydroxycholesterol and 5alpha,6alpha/5beta,6beta-epoxycholesterol as well as the 7alpha-hydroperoxide derivative of cholesterol. Thus, SULT2B1b, by acting on a variety of oxysterols, offers a potential pathway for modulating in vivo the injurious effects of these compounds.
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Affiliation(s)
- Hirotoshi Fuda
- Section on Steroid Regulation, Endocrinology and Reproduction Research Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-4510, USA
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Javitt NB. Oxysterols: functional significance in fetal development and the maintenance of normal retinal function. Curr Opin Lipidol 2007; 18:283-8. [PMID: 17495602 DOI: 10.1097/mol.0b013e328133851e] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW Recent findings extend the biologic activities of oxysterols as ligands for nuclear receptors to a role in morphogenesis during fetal development and to a role in the metabolism of photooxidation products of cholesterol in the retina. RECENT FINDINGS A 1000-fold increase of the 27-hydroxy metabolite of 7-dehydrocholesterol in the plasma of children with Smith-Lemli-Opitz syndrome imply that intermediates in cholesterol synthesis follow alternate pathways of metabolism that generate novel oxysterols. A mouse model also finds an increase in sterol intermediates as the proximate cause of dysmorphisms. A role for oxysterols in the effects of Sonic hedgehog protein focuses on their role in normal fetal development. Both CYP27A1 and CYP46A1 are expressed in primate retina indicating that local metabolism of 7-ketocholesterol to nontoxic derivatives is important for preventing retinal degeneration. SUMMARY Recent data expand the functional roles of oxysterols to fetal development and to the detoxification of oxidation products of cholesterol. This review shifts the focus of attention from studies of their ligand-binding activity to studies of animal models that indicate a number of important biologic effects during fetal development and during the aging process.
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Affiliation(s)
- Norman B Javitt
- New York University School of Medicine, New York, New York, USA.
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Lee JW, Fuda H, Javitt NB, Strott CA, Rodriguez IR. Expression and localization of sterol 27-hydroxylase (CYP27A1) in monkey retina. Exp Eye Res 2006; 83:465-9. [PMID: 16549062 PMCID: PMC2806429 DOI: 10.1016/j.exer.2005.11.018] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2005] [Accepted: 11/11/2005] [Indexed: 01/11/2023]
Abstract
Sterol 27-hydroxylase (CYP27A1) is a mitochondrial P-450 enzyme with broad substrate specificity for C27 sterols including 7-ketocholesterol (7kCh). CYP27A1 is widely expressed in human tissues but has not been previously demonstrated in the retina. In this study, we examined the expression and localization of CYP27A1 in the monkey retina where it localized mainly to the photoreceptor inner segments. CYP27A1 was also observed in Müller cells with faint immuno staining detected in the RPE and choriocapillaris. We also determined that the 27-hydroxylation of 7-ketocholesterol (27OH7kCh) rendered it non-toxic to cultured RPE cells. Moreover, the 27OH7kCh when mixed with 7-ketocholesterol significantly reduced the toxicity of 7-ketocholesterol. These data, when taken in context of the known functions of CYP27A1 imply that expression in the retina serves to modify the biological activity of oxidized sterols that are either transported or generated locally by photo-oxidation.
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Affiliation(s)
- Jung Wha Lee
- Section on Mechanisms of Retinal Diseases, Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hirotoshi Fuda
- Section on Steroid Regulation, Endocrinology and Reproduction Research Branch, National Institute of Child Health and Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Norman B. Javitt
- Divisions of Gastroenterology, New York University Medical Center, New York, NY 10016, USA
| | - Charles A. Strott
- Section on Steroid Regulation, Endocrinology and Reproduction Research Branch, National Institute of Child Health and Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ignacio R. Rodriguez
- Section on Mechanisms of Retinal Diseases, Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
- Corresponding author. National Eye Institute, NIH, Mechanisms of Retinal Diseases Section, LRCMB, 7 Memorial Drive, MSC0706, Building 7, Room 302, Bethesda, MD 20892, USA. Tel.: +1 301 496 1395; fax: +1 301 402 1883. (I.R. Rodriguez)
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Schmitz G, Langmann T. Transcriptional regulatory networks in lipid metabolism control ABCA1 expression. Biochim Biophys Acta Mol Cell Biol Lipids 2005; 1735:1-19. [PMID: 15922656 DOI: 10.1016/j.bbalip.2005.04.004] [Citation(s) in RCA: 144] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2005] [Revised: 04/22/2005] [Accepted: 04/22/2005] [Indexed: 10/25/2022]
Abstract
The ATP-binding cassette transporters, ABCA1 and ABCG1, are major players in mediating cellular efflux of phospholipids and cholesterol to apoA-I containing lipoproteins including prebeta-HDL and alphaHDL and thereby exert important antiatherogenic properties. Although the exact mechanisms how ABC transporters mediate lipid transport are not completely resolved, recent evidence from several laboratories including ours suggests that vesicular transport processes involving different interactive proteins like beta2-syntrophin, alpha1-syntrophin, Lin7, and cdc42 are critically involved in cellular lipid homeostasis controlled by ABCA1 and ABCG1. Besides sterols and fatty acids as known physiological modulators of the LXR/RXR and SREBP pathways, a growing list of natural and synthetic substances and metabolic regulators such as retinoids, PPAR-ligands, hormones, cytokines, and drugs are particularly effective in modulating ABCA1 and ABCG1 gene expression. Although ABCA1 protein amounts are regulated at the level of stability, the majority of potent activating and repressing mechanisms on ABCA1 function directly act on the ABCA1 gene promoter. Among the inducing factors, liver-X-receptors (LXR), retinoic acid receptors (RAR) and peroxisome proliferator-activated receptors (PPARs) along with their coactivators provide an amplification loop for ABCA1 and ABCG1 expression. The ABCA1 promoter is further stimulated by the ubiquitous factor Sp1 and the hypoxia-induced factor 1 (HIF1), which bind to GC-boxes and the E-box, respectively. Shutdown of ABCA1 expression in the absence of sterols or in certain tissues is mediated by corepressor complexes involving unliganded LXR, sterol-regulatory element binding protein 2 (SREBP2), Sp3, and the SCAN-domain protein ZNF202, which also impacts nuclear receptor signaling. Thus, a highly sophisticated transcriptional network controls the balanced expression of ABCA1.
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Affiliation(s)
- Gerd Schmitz
- Institute of Clinical Chemistry and Laboratory Medicine, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93042 Regensburg, Germany.
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Quinn C, Jessup W, Wong J, Kritharides L, Brown A. Expression and regulation of sterol 27-hydroxylase (CYP27A1) in human macrophages: a role for RXR and PPARgamma ligands. Biochem J 2005; 385:823-30. [PMID: 15533057 PMCID: PMC1134759 DOI: 10.1042/bj20041776] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
CYP27A1 (sterol 27-hydroxylase) catalyses an important sterol elimination pathway in the human macrophage, and consequently may protect against atherosclerosis. We studied the expression and regulation of CYP27A1 in a human macrophage-like cell-line, THP-1, and primary HMDMs (human monocyte-derived macrophages). In both macrophage cell types, we found that CYP27A1 expression is independent of cellular cholesterol levels and of LXR (liver X receptor)-dependent control of transcription. However, the RXR (retinoid X receptor) ligand, 9-cis-retinoic acid, upregulates CYP27A1 expression. Of the RXR heterodimeric partners tested, PPAR (peroxisome-proliferator-activated receptor) gamma ligands significantly increased CYP27A1 mRNA levels. Its reversal by a PPARgamma antagonist demonstrated the specificity of this effect. Interestingly, HMDMs express markedly higher levels of CYP27A1 than THP-1 macrophages, and this difference was reflected in both protein levels and enzyme activities between the two cell types. In conclusion, stimulation of CYP27A1 by PPARgamma may represent a key previously unrecognized mechanism by which PPARgamma protects against atherosclerosis.
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Affiliation(s)
- Carmel M. Quinn
- *Centre for Vascular Research, School of Medical Sciences, University of New South Wales, Sydney, NSW 2052, Australia
- †Centre for Vascular Research, Department of Haematology, Prince of Wales Hospital, Barker Street, Randwick, NSW 2031, Australia
| | - Wendy Jessup
- *Centre for Vascular Research, School of Medical Sciences, University of New South Wales, Sydney, NSW 2052, Australia
- †Centre for Vascular Research, Department of Haematology, Prince of Wales Hospital, Barker Street, Randwick, NSW 2031, Australia
- To whom correspondence should be addressed at the Centre for Vascular Research, School of Medical Sciences, University of New South Wales, Sydney, NSW 2052, Australia (email )
| | - Jenny Wong
- ‡School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Leonard Kritharides
- *Centre for Vascular Research, School of Medical Sciences, University of New South Wales, Sydney, NSW 2052, Australia
- †Centre for Vascular Research, Department of Haematology, Prince of Wales Hospital, Barker Street, Randwick, NSW 2031, Australia
- §Department of Cardiology, Concord Hospital, Hospital Road, Concord, NSW 2139, Australia
| | - Andrew J. Brown
- ‡School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
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Abstract
Oxysterols (oxygenated forms of cholesterol) are present at low levels in the circulation and accumulate is plasma and tissues in some pathologies. In atherosclerotic lesions, 7-oxygenated oxysterols, predominantly 7-ketocholesterol, accumulate and have been implicated in the pathology of the disease. Therefore, knowledge of the mechanisms for 7-ketocholesterol generation and metabolism may provide therapeutic drug targets. There is some in vivo and in vitro evidence that sterol 27-hydroxylase acts on 7-ketocholesterol to initiate its degradation to more polar, water-soluble products. Recent studies indicate an alternative mechanism, in which 7-ketocholesterol is reduced to 7 beta-hydroxycholesterol by 11 beta-hydroxysteroid dehydrogenase type 1.
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Affiliation(s)
- Wendy Jessup
- Centre for Vascular Research at School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia.
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Davies JD, Carpenter KLH, Challis IR, Figg NL, McNair R, Proudfoot D, Weissberg PL, Shanahan CM. Adipocytic differentiation and liver x receptor pathways regulate the accumulation of triacylglycerols in human vascular smooth muscle cells. J Biol Chem 2004; 280:3911-9. [PMID: 15548517 DOI: 10.1074/jbc.m410075200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lipid accumulation by vascular smooth muscle cells (VSMC) is a feature of atherosclerotic plaques. In this study we describe two mechanisms whereby human VSMC foam cell formation is driven by de novo synthesis of fatty acids leading to triacylglycerol accumulation in intracellular vacuoles, a process distinct from serum lipoprotein uptake. VSMC cultured in adipogenic differentiation medium accumulated lipids and were induced to express the adipocyte marker genes adipsin, adipocyte fatty acid-binding protein, C/EBPalpha, PPARgamma, and leptin. However, complete adipocyte differentiation was not observed as numerous genes present in mature adipocytes were not detected, and the phenotype was reversible. The rate of lipid accumulation was not affected by PPARgamma agonists, but screening for the effects of other nuclear receptor agonists showed that activation of the liver X receptors (LXR) dramatically promoted lipid accumulation in VSMC. Both LXRalpha and LXRbeta were present in VSMC, and their activation with TO901317 resulted in induction of the lipogenic genes fatty acid synthetase, sterol regulatory element binding protein (SREBP1c), and stearoyl-CoA desaturase. 27-Hydroxycholesterol, an abundant oxysterol synthesized by VSMC acted as an LXR antagonist and, therefore, may have a protective role in preventing foam cell formation. Immunohistochemistry showed that VSMC within atherosclerotic plaques express adipogenic and lipogenic markers, suggesting these pathways are present in vivo. Moreover, the development of an adipogenic phenotype in VSMC is consistent with their known phenotypic plasticity and may contribute to their dysfunction in atherosclerotic plaques and, thus, impinge on plaque growth and stability.
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Affiliation(s)
- John D Davies
- Department of Medicine, University of Cambridge, ACCI, Box 110, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 2QQ, United Kingdom.
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Souidi M, Dubrac S, Parquet M, Volle DH, Lobaccaro JMA, Mathé D, Combes O, Scanff P, Lutton C, Aigueperse J. Les oxystérols : métabolisme, rôles biologiques et pathologies associées. ACTA ACUST UNITED AC 2004; 28:279-93. [PMID: 15094678 DOI: 10.1016/s0399-8320(04)94919-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Maâmar Souidi
- Département de Protection de la santé de l'Homme et de Dosimétrie, Section Autonome de Radiobiologie Appliquée à la Médecine, Institut de Radioprotection et de Sûreté Nucléaire, IRSN, B.P No 17, 92262 Fontenay-aux-roses Cedex
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Schweizer RAS, Zürcher M, Balazs Z, Dick B, Odermatt A. Rapid hepatic metabolism of 7-ketocholesterol by 11beta-hydroxysteroid dehydrogenase type 1: species-specific differences between the rat, human, and hamster enzyme. J Biol Chem 2004; 279:18415-24. [PMID: 14973125 DOI: 10.1074/jbc.m313615200] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The role of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) in the local activation of the glucocorticoid receptor by converting inactive 11-ketoglucocorticoids to active 11beta-hydroxyglucocorticoids is well established. Currently, 11beta-HSD1 is considered a promising target for treatment of obese and diabetic patients. Here, we demonstrate a role of 11beta-HSD1 in the metabolism of 7-ketocholesterol (7KC), the major dietary oxysterol. Comparison of recombinant 11beta-HSD1, transiently expressed in human embryonic kidney 293 cells, revealed the stereo-specific interconversion of 7KC and 7beta-hydroxycholesterol by rat and human 11beta-HSD1, whereas the hamster enzyme interconverted 7alpha-hydroxycholesterol, 7beta-hydroxycholesterol, and 7KC. In contrast to lysates, which efficiently catalyzed both oxidation and reduction, intact cells exclusively reduced 7KC. These findings were confirmed using rat and hamster liver homogenates, intact rat hepatocytes, and intact hamster liver tissue slices. Reduction of 7KC was abolished upon inhibition of 11beta-HSD1 by carbenoxolone (CBX) or 2'-hydroxyflavanone. In vivo, after gavage feeding rats, 7KC rapidly appeared in the liver and was converted to 7beta-hydroxycholesterol. CBX significantly decreased the ratio of 7beta-hydroxycholesterol to 7KC, supporting the evidence from cell culture experiments for 11beta-HSD1-dependent reduction of 7KC to 7beta-hydroxycholesterol. Upon inhibition of 11beta-HSD1 by CBX, 7KC tended to accumulate in the liver, and plasma 7KC concentration increased. Together, our results suggest that 11beta-HSD1 efficiently catalyzes the first step in the rapid hepatic metabolism of dietary 7KC, which may explain why dietary 7KC has little or no effect on the development of atherosclerosis.
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Affiliation(s)
- Roberto A S Schweizer
- Division of Nephrology and Hypertension, Department of Clinical Research, University of Berne, 3010 Berne, Switzerland
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