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Duara J, Torres M, Gurumani M, Molina David J, Njeim R, Kim JJ, Mitrofanova A, Ge M, Sloan A, Müller-Deile J, Schiffer M, Merscher S, Fornoni A. Oxysterol-binding protein-like 7 deficiency leads to ER stress-mediated apoptosis in podocytes and proteinuria. Am J Physiol Renal Physiol 2024; 327:F340-F350. [PMID: 38961844 DOI: 10.1152/ajprenal.00319.2023] [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: 10/09/2023] [Revised: 06/21/2024] [Accepted: 06/21/2024] [Indexed: 07/05/2024] Open
Abstract
Chronic kidney disease (CKD) is associated with renal lipid dysmetabolism among a variety of other pathways. We recently demonstrated that oxysterol-binding protein-like 7 (OSBPL7) modulates the expression and function of ATP-binding cassette subfamily A member 1 (ABCA1) in podocytes, a specialized type of cell essential for kidney filtration. Drugs that target OSBPL7 lead to improved renal outcomes in several experimental models of CKD. However, the role of OSBPL7 in podocyte injury remains unclear. Using mouse models and cellular assays, we investigated the influence of OSBPL7 deficiency on podocytes. We demonstrated that reduced renal OSBPL7 levels as observed in two different models of experimental CKD are linked to increased podocyte apoptosis, primarily mediated by heightened endoplasmic reticulum (ER) stress. Although as expected, the absence of OSBPL7 also resulted in lipid dysregulation (increased lipid droplets and triglycerides content), OSBPL7 deficiency-related lipid dysmetabolism did not contribute to podocyte injury. Similarly, we demonstrated that the decreased autophagic flux we observed in OSBPL7-deficient podocytes was not the mechanistic link between OSBPL7 deficiency and apoptosis. In a complementary zebrafish model, osbpl7 knockdown was sufficient to induce proteinuria and morphological damage to the glomerulus, underscoring its physiological relevance. Our study sheds new light on the mechanistic link between OSBPL7 deficiency and podocyte injury in glomerular diseases associated with CKD, and it strengthens the role of OSBPL7 as a novel therapeutic target.NEW & NOTEWORTHY OSBPL7 and ER stress comprise a central mechanism in glomerular injury. This study highlights a crucial link between OSBPL7 deficiency and ER stress in CKD. OSBPL7 deficiency causes ER stress, leading to podocyte apoptosis. There is a selective effect on lipid homeostasis in that OSBPL7 deficiency affects lipid homeostasis, altering cellular triglyceride but not cholesterol content. The interaction of ER stress and apoptosis supports that ER stress, not reduced autophagy, is the main driver of apoptosis in OSBPL7-deficient podocytes.
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Affiliation(s)
- Joanne Duara
- Peggy and Harold Katz Family Drug Discovery Center, University of Miami Miller School of Medicine, Miami, Florida, United States
- Department of Pediatrics/Division of Neonatology, Batchelor Children's Research Institute, Holtz Children's Hospital, University of Miami Miller School of Medicine, Miami, Florida, United States
| | - Maria Torres
- Peggy and Harold Katz Family Drug Discovery Center, University of Miami Miller School of Medicine, Miami, Florida, United States
- Boston University, Boston, Massachusetts, United States
| | - Margaret Gurumani
- Peggy and Harold Katz Family Drug Discovery Center, University of Miami Miller School of Medicine, Miami, Florida, United States
- Boston University, Boston, Massachusetts, United States
| | - Judith Molina David
- Peggy and Harold Katz Family Drug Discovery Center, University of Miami Miller School of Medicine, Miami, Florida, United States
- Katz Family Division of Nephrology and Hypertension, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida, United States
| | - Rachel Njeim
- Peggy and Harold Katz Family Drug Discovery Center, University of Miami Miller School of Medicine, Miami, Florida, United States
- Katz Family Division of Nephrology and Hypertension, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida, United States
| | - Jin-Ju Kim
- Peggy and Harold Katz Family Drug Discovery Center, University of Miami Miller School of Medicine, Miami, Florida, United States
- Katz Family Division of Nephrology and Hypertension, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida, United States
| | - Alla Mitrofanova
- Peggy and Harold Katz Family Drug Discovery Center, University of Miami Miller School of Medicine, Miami, Florida, United States
- Katz Family Division of Nephrology and Hypertension, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida, United States
| | - Mengyuan Ge
- Peggy and Harold Katz Family Drug Discovery Center, University of Miami Miller School of Medicine, Miami, Florida, United States
- Katz Family Division of Nephrology and Hypertension, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida, United States
| | - Alexis Sloan
- Peggy and Harold Katz Family Drug Discovery Center, University of Miami Miller School of Medicine, Miami, Florida, United States
- Katz Family Division of Nephrology and Hypertension, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida, United States
| | - Janina Müller-Deile
- Department of Nephrology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Mario Schiffer
- Department of Nephrology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
- Mount Desert Island Biological Laboratories, Salisbury Cove, Maine, United States
| | - Sandra Merscher
- Peggy and Harold Katz Family Drug Discovery Center, University of Miami Miller School of Medicine, Miami, Florida, United States
- Katz Family Division of Nephrology and Hypertension, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida, United States
| | - Alessia Fornoni
- Peggy and Harold Katz Family Drug Discovery Center, University of Miami Miller School of Medicine, Miami, Florida, United States
- Katz Family Division of Nephrology and Hypertension, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida, United States
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Lin Y, Ran L, Du X, Yang H, Wu Y. Oxysterol-Binding Protein: new insights into lipid transport functions and human diseases. Biochim Biophys Acta Mol Cell Biol Lipids 2023; 1868:159365. [PMID: 37455011 DOI: 10.1016/j.bbalip.2023.159365] [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: 05/04/2023] [Revised: 07/10/2023] [Accepted: 07/11/2023] [Indexed: 07/18/2023]
Abstract
Oxysterol-binding protein (OSBP) mediates lipid exchange between organelles at membrane contact sites, thereby regulating lipid dynamics and homeostasis. How OSBP's lipid transfer function impacts health and disease remain to be elucidated. In this review, we first summarize the structural characteristics and lipid transport functions of OSBP, and then focus on recent progresses linking OSBP with fatty liver disease, diabetes, lysosome-related diseases, cancer and viral infections, with the aim of discovering novel therapeutic strategies for common human diseases.
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Affiliation(s)
- Yani Lin
- Shandong Provincial Hospital, School of Laboratory Animal & Shandong Laboratory Animal Center, Science and Technology Innovation Center, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong 250021, China
| | - Liyuan Ran
- Shandong Provincial Hospital, School of Laboratory Animal & Shandong Laboratory Animal Center, Science and Technology Innovation Center, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong 250021, China; Institute for Genome Engineered Animal Models of Human Diseases, National Center of Genetically Engineered Animal Models for International Research, Dalian Medical University, Dalian, Liaoning 116044, China
| | - Ximing Du
- School of Biotechnology and Biomolecular Sciences, the University of New South Wales, Sydney, NSW 2052, Australia
| | - Hongyuan Yang
- School of Biotechnology and Biomolecular Sciences, the University of New South Wales, Sydney, NSW 2052, Australia.
| | - Yingjie Wu
- Shandong Provincial Hospital, School of Laboratory Animal & Shandong Laboratory Animal Center, Science and Technology Innovation Center, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong 250021, China; Institute for Genome Engineered Animal Models of Human Diseases, National Center of Genetically Engineered Animal Models for International Research, Dalian Medical University, Dalian, Liaoning 116044, China; Department of Molecular Pathobiology, New York University College of Dentistry, New York 10010, USA.
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3
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Shinozaki Y, Leung A, Namekata K, Saitoh S, Nguyen HB, Takeda A, Danjo Y, Morizawa YM, Shigetomi E, Sano F, Yoshioka N, Takebayashi H, Ohno N, Segawa T, Miyake K, Kashiwagi K, Harada T, Ohnuma SI, Koizumi S. Astrocytic dysfunction induced by ABCA1 deficiency causes optic neuropathy. SCIENCE ADVANCES 2022; 8:eabq1081. [PMID: 36332025 PMCID: PMC9635836 DOI: 10.1126/sciadv.abq1081] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 09/16/2022] [Indexed: 06/16/2023]
Abstract
Astrocyte abnormalities have received great attention for their association with various diseases in the brain but not so much in the eye. Recent independent genome-wide association studies of glaucoma, optic neuropathy characterized by retinal ganglion cell (RGC) degeneration, and vision loss found that single-nucleotide polymorphisms near the ABCA1 locus were common risk factors. Here, we show that Abca1 loss in retinal astrocytes causes glaucoma-like optic neuropathy in aged mice. ABCA1 was highly expressed in retinal astrocytes in mice. Thus, we generated macroglia-specific Abca1-deficient mice (Glia-KO) and found that aged Glia-KO mice had RGC degeneration and ocular dysfunction without affected intraocular pressure, a conventional risk factor for glaucoma. Single-cell RNA sequencing revealed that Abca1 deficiency in aged Glia-KO mice caused astrocyte-triggered inflammation and increased the susceptibility of certain RGC clusters to excitotoxicity. Together, astrocytes play a pivotal role in eye diseases, and loss of ABCA1 in astrocytes causes glaucoma-like neuropathy.
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Affiliation(s)
- Youichi Shinozaki
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
- GLIA Center, University of Yamanashi, Yamanashi, Japan
| | - Alex Leung
- UCL Institute of Ophthalmology, University College London, London, UK
| | - Kazuhiko Namekata
- Visual Research Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Sei Saitoh
- Section of Electron Microscopy, Supportive Center for Brain Research, National Institute for Physiological Sciences (NIPS), Aichi, Japan
- Department of Anatomy II and Cell Biology, Fujita Health University School of Medicine, Aichi, Japan
| | - Huy Bang Nguyen
- Division of Neurobiology and Bioinformatics, NIPS, Aichi, Japan
- Department of Anatomy, Faculty of Medicine, University of Medicine and Pharmacy (UMP), Ho Chi Minh City, Vietnam
| | - Akiko Takeda
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Yosuke Danjo
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Yosuke M. Morizawa
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Eiji Shigetomi
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
- GLIA Center, University of Yamanashi, Yamanashi, Japan
| | - Fumikazu Sano
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Nozomu Yoshioka
- Division of Neurobiology and Anatomy, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Hirohide Takebayashi
- Division of Neurobiology and Anatomy, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Nobuhiko Ohno
- Division of Ultrastructural Research, NIPS, Aichi, Japan
- Department of Anatomy, Jichi Medical University, Tochigi, Japan
| | - Takahiro Segawa
- Center for Life Science Research, University of Yamanashi, Yamanashi, Japan
| | - Kunio Miyake
- Department of Health Sciences, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Kenji Kashiwagi
- Department of Ophthalmology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Takayuki Harada
- Visual Research Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Shin-ichi Ohnuma
- UCL Institute of Ophthalmology, University College London, London, UK
| | - Schuichi Koizumi
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
- GLIA Center, University of Yamanashi, Yamanashi, Japan
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Wright MB, Varona Santos J, Kemmer C, Maugeais C, Carralot JP, Roever S, Molina J, Ducasa GM, Mitrofanova A, Sloan A, Ahmad A, Pedigo C, Ge M, Pressly J, Barisoni L, Mendez A, Sgrignani J, Cavalli A, Merscher S, Prunotto M, Fornoni A. Compounds targeting OSBPL7 increase ABCA1-dependent cholesterol efflux preserving kidney function in two models of kidney disease. Nat Commun 2021; 12:4662. [PMID: 34341345 PMCID: PMC8329197 DOI: 10.1038/s41467-021-24890-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 07/06/2021] [Indexed: 02/08/2023] Open
Abstract
Impaired cellular cholesterol efflux is a key factor in the progression of renal, cardiovascular, and autoimmune diseases. Here we describe a class of 5-arylnicotinamide compounds, identified through phenotypic drug discovery, that upregulate ABCA1-dependent cholesterol efflux by targeting Oxysterol Binding Protein Like 7 (OSBPL7). OSBPL7 was identified as the molecular target of these compounds through a chemical biology approach, employing a photoactivatable 5-arylnicotinamide derivative in a cellular cross-linking/immunoprecipitation assay. Further evaluation of two compounds (Cpd A and Cpd G) showed that they induced ABCA1 and cholesterol efflux from podocytes in vitro and normalized proteinuria and prevented renal function decline in mouse models of proteinuric kidney disease: Adriamycin-induced nephropathy and Alport Syndrome. In conclusion, we show that small molecule drugs targeting OSBPL7 reveal an alternative mechanism to upregulate ABCA1, and may represent a promising new therapeutic strategy for the treatment of renal diseases and other disorders of cellular cholesterol homeostasis.
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Affiliation(s)
- Matthew B Wright
- Pharma Research and Early Development (pRED), Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Javier Varona Santos
- Katz Family Division of Nephrology and Hypertension, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL, USA
- Peggy and Harold Katz Family Drug Discovery Center, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - Christian Kemmer
- Pharma Research and Early Development (pRED), Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Cyrille Maugeais
- Pharma Research and Early Development (pRED), Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Jean-Philippe Carralot
- Pharma Research and Early Development (pRED), Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Stephan Roever
- Pharma Research and Early Development (pRED), Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Judith Molina
- Katz Family Division of Nephrology and Hypertension, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL, USA
- Peggy and Harold Katz Family Drug Discovery Center, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - G Michelle Ducasa
- Katz Family Division of Nephrology and Hypertension, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL, USA
- Peggy and Harold Katz Family Drug Discovery Center, University of Miami, Miller School of Medicine, Miami, FL, USA
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Alla Mitrofanova
- Katz Family Division of Nephrology and Hypertension, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL, USA
- Peggy and Harold Katz Family Drug Discovery Center, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - Alexis Sloan
- Katz Family Division of Nephrology and Hypertension, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL, USA
- Peggy and Harold Katz Family Drug Discovery Center, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - Anis Ahmad
- Sylvester Comprehensive Cancer Center, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - Christopher Pedigo
- Katz Family Division of Nephrology and Hypertension, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL, USA
- Peggy and Harold Katz Family Drug Discovery Center, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - Mengyuan Ge
- Katz Family Division of Nephrology and Hypertension, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL, USA
- Peggy and Harold Katz Family Drug Discovery Center, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - Jeffrey Pressly
- Katz Family Division of Nephrology and Hypertension, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL, USA
- Peggy and Harold Katz Family Drug Discovery Center, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - Laura Barisoni
- Department of Pathology, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - Armando Mendez
- Diabetes Research Institute, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - Jacopo Sgrignani
- Institute for Research in Biomedicine, Università della Svizzera Italiana, Bellinzona, Switzerland
| | - Andrea Cavalli
- Institute for Research in Biomedicine, Università della Svizzera Italiana, Bellinzona, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Sandra Merscher
- Katz Family Division of Nephrology and Hypertension, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL, USA
- Peggy and Harold Katz Family Drug Discovery Center, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - Marco Prunotto
- Pharma Research and Early Development (pRED), Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Basel, Switzerland.
- School of Pharmaceutical Sciences, University of Geneva, Geneva, Switzerland.
| | - Alessia Fornoni
- Katz Family Division of Nephrology and Hypertension, Department of Medicine, University of Miami, Miller School of Medicine, Miami, FL, USA.
- Peggy and Harold Katz Family Drug Discovery Center, University of Miami, Miller School of Medicine, Miami, FL, USA.
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Guidara W, Messedi M, Maalej M, Naifar M, Khrouf W, Grayaa S, Maalej M, Bonnefont-Rousselot D, Lamari F, Ayadi F. Plasma oxysterols: Altered level of plasma 24-hydroxycholesterol in patients with bipolar disorder. J Steroid Biochem Mol Biol 2021; 211:105902. [PMID: 33901658 DOI: 10.1016/j.jsbmb.2021.105902] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 04/09/2021] [Accepted: 04/20/2021] [Indexed: 12/13/2022]
Abstract
Cholesterol and its oxygenated metabolites, including oxysterols, are intensively investigated as potential players in the pathophysiology of brain disorders. Altered oxysterol levels have been described in patients with numerous neuropsychiatric disorders. Recent studies have shown that Bipolar disorder (BD) is associated with the disruption of cholesterol metabolism. The present study was aimed at investigating the profile of oxysterols in plasma, their ratio to total cholesterol and their association with clinical parameters in patients with BD. Thirty three men diagnosed with BD and forty healthy controls matched for age and sex were included in the study. Oxysterol levels were measured by isotope-dilution ultra-performance liquid chromatography-tandem mass spectrometry. Significantly higher levels were observed for cholestane-3β,5α,6β-triol, 27-hydroxycholesterol (27-OHC) and Cholestanol in patients with BD. The concentration of 24-hydroxycholesterol (24-OHC) was significantly lower in patients compared to controls. 24-OHC was also negatively correlated to MAS subscale score (r =-0.343; p = 0.049). In patients, 24-OHC was inversely correlated with age (r = -0.240; p = 0.045). Multivariate analysis found that BD acute decompensation was independently related to the rise in plasma 24-OHC (p = 0.002; OR = 0.966, 95 % CI [0.945 - 0.987]). However, the 24-OHC assay relevance as a biomarker of this disease deserves further investigation in other studies.
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Affiliation(s)
- Wassim Guidara
- Laboratory of Research "Molecular Basis of Human Diseases", LR19ES13, Faculty of Medicine, University of Sfax, Sfax, Tunisia.
| | - Meriam Messedi
- Laboratory of Research "Molecular Basis of Human Diseases", LR19ES13, Faculty of Medicine, University of Sfax, Sfax, Tunisia
| | - Manel Maalej
- Psychiatry C-department, University of Sfax & Hédi Chaker Hospital, Sfax, Tunisia
| | - Manel Naifar
- Laboratory of Research "Molecular Basis of Human Diseases", LR19ES13, Faculty of Medicine, University of Sfax, Sfax, Tunisia; Laboratory of Biochemistry, University of Sfax & Habib Bourguiba Hospital, Sfax, Tunisia
| | - Walid Khrouf
- AP-HP, Sorbonne University, La Pitié-Salpêtrière University Hospital, Department of Metabolic Biochemistry, Paris, France
| | - Sahar Grayaa
- Laboratory of Research "Molecular Basis of Human Diseases", LR19ES13, Faculty of Medicine, University of Sfax, Sfax, Tunisia
| | - Mohamed Maalej
- Psychiatry C-department, University of Sfax & Hédi Chaker Hospital, Sfax, Tunisia
| | - Dominique Bonnefont-Rousselot
- AP-HP, Sorbonne University, La Pitié-Salpêtrière University Hospital, Department of Metabolic Biochemistry, Paris, France; UTCBS, U1267 Inserm, UMR 8258 CNRS, Université de Paris, Paris, France
| | - Foudil Lamari
- AP-HP, Sorbonne University, La Pitié-Salpêtrière University Hospital, Department of Metabolic Biochemistry, Paris, France
| | - Fatma Ayadi
- Laboratory of Research "Molecular Basis of Human Diseases", LR19ES13, Faculty of Medicine, University of Sfax, Sfax, Tunisia; Laboratory of Biochemistry, University of Sfax & Habib Bourguiba Hospital, Sfax, Tunisia
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Srivastava N, Cefalu AB, Averna M, Srivastava RAK. Rapid degradation of ABCA1 protein following cAMP withdrawal and treatment with PKA inhibitor suggests ABCA1 is a short-lived protein primarily regulated at the transcriptional level. J Diabetes Metab Disord 2020; 19:363-371. [PMID: 32550187 DOI: 10.1007/s40200-020-00517-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 03/12/2020] [Indexed: 01/08/2023]
Abstract
Objectives ATP-binding cassette transporter A1 (ABCA1) is a key player in the reverse cholesterol transport (RCT) and HDL biogenesis. Since RCT is compromised as a result of ABCA1 dysfunction in diabetic state, the objective of this study was to investigate the regulation of ABCA1 in a stably transfected 293 cells expressing ABCA1 under the control of cAMP response element. Methods To delineate transcriptional and posttranscriptional regulation of ABCA1, 293 cells were stably transfected with the full length ABCA1 cDNA under the control of CMV promoter harboring cAMP response element. cAMP-mediated regulation of ABCA1 and cholesterol efflux were studied in the presence of 8-Br-cAMP and after withdrawal of 8-Br-cAMP. The mechanism of cAMP-mediated transcriptional induction of the ABCA1 gene was studied in protein kinase A (PKA) inhibitors-treated cells. Results The transfected 293 cells expressed high levels of ABCA1, while non-transfected wild-type 293 cells showed very low levels of ABCA1. Treatments of transfected cells with 8-Br-cAMP increased ABCA1 protein by 10-fold and mRNA by 20-fold. Cholesterol efflux also increased in parallel. Withdrawal of 8-Br-cAMP caused time-dependent rapid diminution of ABCA1 protein and mRNA, suggesting ABCA1 regulation at the transcriptional level. Treatment with PKA inhibitors abolished the cAMP-mediated induction of the ABCA1 mRNA and protein, resulting dampening of ABCA1-dependent cholesterol efflux. Conclusions These results demonstrate that transfected cell line mimics cAMP response similar to normal cells with natural ABCA1 promoter and suggest that ABCA1 is a short-lived protein primarily regulated at the transcriptional level to maintain cellular cholesterol homeostasis.
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Zhao K, Foster J, Ridgway ND. Oxysterol-binding protein-related protein 1 variants have opposing cholesterol transport activities from the endolysosomes. Mol Biol Cell 2020; 31:793-802. [PMID: 32023146 PMCID: PMC7185962 DOI: 10.1091/mbc.e19-12-0697] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
OSBPL1 encodes the full-length oxysterol-binding protein-related protein ORP1L, which transports LDL-derived cholesterol at membrane contacts between the late endosomes/lysosomes (LEL) and the endoplasmic reticulum (ER). OSBPL1 also encodes the truncated variant ORP1S that contains only the C-terminal lipid binding domain. HeLa cells in which both variants were knocked out (ORP1-null) were used to determine the functional relationship between ORP1L and ORP1S with respect to cellular cholesterol localization and regulation. ORP1-null cells accumulated cholesterol in LEL and had reduced plasma membrane (PM) cholesterol. PM cholesterol was restored by expression of wild-type ORP1S or a phosphatidylinositol phosphate-binding mutant but not by a sterol-binding mutant. Expression of ORP2, another truncated variant, also restored PM cholesterol in ORP1-null cells. Consistent with a LEL-to-PM cholesterol transport activity, a small fraction of ORP1S was detected on the PM. As a consequence of reduced delivery of cholesterol to the PM in ORP1-null cells, cholesterol was diverted to the ER resulting in normalization of de novo cholesterol synthesis. The deficiency in PM cholesterol also reduced ABCA1-dependent cholesterol efflux and LDL receptor activity in ORP1-null cells. We conclude that ORP1S, which lacks discrete membrane-targeting motifs, transports cholesterol from LEL to the PM.
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Affiliation(s)
- Kexin Zhao
- Departments of Pediatrics and Biochemistry & Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Jason Foster
- Departments of Pediatrics and Biochemistry & Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Neale D Ridgway
- Departments of Pediatrics and Biochemistry & Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
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Liu H, Huang S. Role of oxysterol-binding protein-related proteins in malignant human tumours. World J Clin Cases 2020; 8:1-10. [PMID: 31970164 PMCID: PMC6962060 DOI: 10.12998/wjcc.v8.i1.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 12/11/2019] [Accepted: 12/13/2019] [Indexed: 02/05/2023] Open
Abstract
The oxysterol-binding protein-related protein (ORP) family is a group of proteins that mediate oxysterol metabolism and bioactivity in cells. ORPs constitute a large family of lipid transfer proteins. Much of the current evidence indicates that certain members of the family of oxysterol-binding proteins (OSBPs) can lead to cancer. Many studies have revealed the putative roles of OSBPs in various cancer types. However, the exact effects and mechanisms of action of members of the OSBP/ORP family in cancer initiation and progression are currently unclear. This review focuses on ORP family members that can accelerate human tumour cell proliferation, migration, and invasion. The mechanisms and functions of various ORPs are introduced in detail. We also attempt to identify the roles of these proteins in malignant tumours with the ultimate aim of determining the exact role of the OSBP/ORP family in human tumour cells.
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Affiliation(s)
- Hao Liu
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, Henan Province, China
| | - Shuai Huang
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, Henan Province, China
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9
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Arnal-Levron M, Chen Y, Greimel P, Calevro F, Gaget K, Riols F, Batut A, Bertrand-Michel J, Hullin-Matsuda F, Olkkonen VM, Delton I, Luquain-Costaz C. Bis(monoacylglycero)phosphate regulates oxysterol binding protein-related protein 11 dependent sterol trafficking. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1864:1247-1257. [DOI: 10.1016/j.bbalip.2019.05.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 05/21/2019] [Accepted: 05/23/2019] [Indexed: 02/06/2023]
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10
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Wang Y, Ji X, Dai S, Liu H, Yan D, Zhou Y, Gu J, Shi H. Cadmium induced redistribution of cholesterol by upregulating ABCA1 and downregulating OSBP. J Inorg Biochem 2018; 189:199-207. [DOI: 10.1016/j.jinorgbio.2018.09.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 09/10/2018] [Accepted: 09/26/2018] [Indexed: 02/08/2023]
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11
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Koubek EJ, Weissenrieder JS, Neighbors JD, Hohl RJ. Schweinfurthins: Lipid Modulators with Promising Anticancer Activity. Lipids 2018; 53:767-784. [DOI: 10.1002/lipd.12088] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 08/30/2018] [Accepted: 08/31/2018] [Indexed: 12/12/2022]
Affiliation(s)
- Emily J. Koubek
- Departments of Medicine and Pharmacology, The Pennsylvania State Cancer Institute; The Pennsylvania State College of Medicine, 500 University Drive Hershey; Hershey PA 17033 USA
| | - Jillian S. Weissenrieder
- Departments of Medicine and Pharmacology; The Pennsylvania State College of Medicine, 500 University Drive Hershey; Hershey PA 17033 USA
| | - Jeffrey D. Neighbors
- Departments of Pharmacology and Medicine; The Pennsylvania State College of Medicine, 500 University Drive Hershey; Hershey PA 17033 USA
| | - Raymond J. Hohl
- Departments of Medicine and Pharmacology, The Pennsylvania State Cancer Institute; The Pennsylvania State College of Medicine, 500 University Drive Hershey; Hershey PA 17033 USA
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12
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Tian S, Ohta A, Horiuchi H, Fukuda R. Oxysterol-binding protein homologs mediate sterol transport from the endoplasmic reticulum to mitochondria in yeast. J Biol Chem 2018; 293:5636-5648. [PMID: 29487131 DOI: 10.1074/jbc.ra117.000596] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 02/09/2018] [Indexed: 11/06/2022] Open
Abstract
Sterols are present in eukaryotic membranes and significantly affect membrane fluidity, permeability, and microdomain formation. They are synthesized in the endoplasmic reticulum (ER) and transported to other organelles and the plasma membrane. Sterols play important roles in the biogenesis and maintenance of mitochondrial membranes. However, the mechanisms underlying ER-to-mitochondrion sterol transport remain to be identified. Here, using purified yeast membrane fractions enriched in ER and mitochondria, we show that the oxysterol-binding protein homologs encoded by the OSH genes in the yeast Saccharomyces cerevisiae mediate sterol transport from the ER to mitochondria. Combined depletion of all seven Osh proteins impaired sterol transport from the ER to mitochondria in vitro; however, sterol transport was recovered at different levels upon adding one of the Osh proteins. Of note, the sterol content in the mitochondrial fraction was significantly decreased in vivo after Osh4 inactivation in a genetic background in which all the other OSH genes were deleted. We also found that Osh5-Osh7 bind cholesterol in vitro We propose a model in which Osh proteins share a common function to transport sterols between membranes, with varying contributions by these proteins, depending on the target membranes. In summary, we have developed an in vitro system to examine intracellular sterol transport and provide evidence for involvement of Osh proteins in sterol transport from the ER to mitochondria in yeast.
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Affiliation(s)
- Siqi Tian
- From the Department of Biotechnology, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan and
| | - Akinori Ohta
- Department of Biological Chemistry, College of Bioscience and Biotechnology, Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi 487-8501, Japan
| | - Hiroyuki Horiuchi
- From the Department of Biotechnology, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan and
| | - Ryouichi Fukuda
- From the Department of Biotechnology, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan and
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13
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Casali BT, Reed-Geaghan EG, Landreth GE. Nuclear receptor agonist-driven modification of inflammation and amyloid pathology enhances and sustains cognitive improvements in a mouse model of Alzheimer's disease. J Neuroinflammation 2018; 15:43. [PMID: 29448961 PMCID: PMC5815248 DOI: 10.1186/s12974-018-1091-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 02/07/2018] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Alzheimer's disease (AD) is a highly prevalent neurodegenerative disorder characterized by pathological hallmarks of beta-amyloid plaque deposits, tau pathology, inflammation, and cognitive decline. Treatment remains a clinical obstacle due to lack of effective therapeutics. Agonists targeting nuclear receptors, such as bexarotene, reversed cognitive deficits regardless of treatment duration and age in murine models of AD. While bexarotene demonstrated marked efficacy in decreasing plaque levels following short-term treatment, prolonged treatment did not modulate plaque burden. This suggested that plaques might reform in mice treated chronically with bexarotene and that cessation of bexarotene treatment before plaques reform might alter amyloid pathology, inflammation, and cognition in AD mice. METHODS We utilized one-year-old APP/PS1 mice that were divided into two groups. We treated one group of mice for 2 weeks with bexarotene. The other group of mice was treated for 2 weeks with bexarotene followed by withdrawal of drug treatment for an additional 2 weeks. Cognition was evaluated using the novel-object recognition test either at the end of bexarotene treatment or the end of the withdrawal period. We then analyzed amyloid pathology and microgliosis at the conclusion of the study in both groups. RESULTS Bexarotene treatment enhanced cognition in APP/PS1 mice similar to previous findings. Strikingly, we observed sustained cognitive improvements in mice in which bexarotene treatment was discontinued for 2 weeks. We observed a sustained reduction in microgliosis and plaque burden following drug withdrawal exclusively in the hippocampus. CONCLUSIONS Our findings demonstrate that bexarotene selectively modifies aspects of neuroinflammation in a region-specific manner to reverse hippocampal-dependent cognitive deficits in AD mice and may provide insight to inform future studies with nuclear receptor agonists.
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Affiliation(s)
- Brad T. Casali
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106 USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202 USA
| | - Erin G. Reed-Geaghan
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106 USA
| | - Gary E. Landreth
- Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106 USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202 USA
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14
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Abstract
Signaling pathways direct organogenesis, often through concentration-dependent effects on cells. The hedgehog pathway enables cells to sense and respond to hedgehog ligands, of which the best studied is sonic hedgehog. Hedgehog signaling is essential for development, proliferation, and stem cell maintenance, and it is a driver of certain cancers. Lipid metabolism has a profound influence on both hedgehog signal transduction and the properties of the ligands themselves, leading to changes in the strength of hedgehog signaling and cellular functions. Here we review the evolving understanding of the relationship between lipids and hedgehog signaling.
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Affiliation(s)
- Robert Blassberg
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - John Jacob
- Nuffield Department of Clinical Neurosciences (NDCN), Level 6, West Wing, John Radcliffe Hospital, Headington, Oxford, OX3 9DU, UK. .,Department of Neurology, West Wing, John Radcliffe Hospital, Headington, Oxford, OX3 9DU, UK. .,Milton Keynes University Hospital, Standing Way, Eaglestone, Milton Keynes, MK6 5LD, UK.
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15
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Kloudova A, Guengerich FP, Soucek P. The Role of Oxysterols in Human Cancer. Trends Endocrinol Metab 2017; 28:485-496. [PMID: 28410994 PMCID: PMC5474130 DOI: 10.1016/j.tem.2017.03.002] [Citation(s) in RCA: 133] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 03/20/2017] [Indexed: 12/12/2022]
Abstract
Oxysterols are oxygenated derivatives of cholesterol formed in the human body or ingested in the diet. By modulating the activity of many proteins [e.g., liver X receptors (LXRs), oxysterol-binding proteins (OSBPs), some ATP-binding cassette (ABC) transporters], oxysterols can affect many cellular functions and influence various physiological processes (e.g., cholesterol metabolism, membrane fluidity regulation, intracellular signaling pathways). Therefore, the role of oxysterols is also important in pathological conditions (e.g., atherosclerosis, diabetes mellitus type 2, neurodegenerative disorders). Finally, current evidence suggests that oxysterols play a role in malignancies such as breast, prostate, colon, and bile duct cancer. This review summarizes the physiological importance of oxysterols in the human body with a special emphasis on their roles in various tumors.
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Affiliation(s)
- Alzbeta Kloudova
- Department of Toxicogenomics, National Institute of Public Health, Prague 100 42, Czech Republic; Third Faculty of Medicine, Charles University, Prague 100 00, Czech Republic
| | - F Peter Guengerich
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Pavel Soucek
- Biomedical Center, Faculty of Medicine in Pilsen, Charles University, Pilsen 323 00, Czech Republic.
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16
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Miller WL. Disorders in the initial steps of steroid hormone synthesis. J Steroid Biochem Mol Biol 2017; 165:18-37. [PMID: 26960203 DOI: 10.1016/j.jsbmb.2016.03.009] [Citation(s) in RCA: 120] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 03/01/2016] [Accepted: 03/03/2016] [Indexed: 12/29/2022]
Abstract
Steroidogenesis begins with cellular internalization of low-density lipoprotein particles and subsequent intracellular processing of cholesterol. Disorders in these steps include Adrenoleukodystrophy, Wolman Disease and its milder variant Cholesterol Ester Storage Disease, and Niemann-Pick Type C Disease, all of which may present with adrenal insufficiency. The means by which cholesterol is directed to steroidogenic mitochondria remains incompletely understood. Once cholesterol reaches the outer mitochondrial membrane, its delivery to the inner mitochondrial membrane is regulated by the steroidogenic acute regulatory protein (StAR). Severe StAR mutations cause classic congenital lipoid adrenal hyperplasia, characterized by lipid accumulation in the adrenal, adrenal insufficiency, and disordered sexual development in 46,XY individuals. The lipoid CAH phenotype, including spontaneous puberty in 46,XX females, is explained by a two-hit model. StAR mutations that retain partial function cause a milder, non-classic disease characterized by glucocorticoid deficiency, with lesser disorders of mineralocorticoid and sex steroid synthesis. Once inside the mitochondria, cholesterol is converted to pregnenolone by the cholesterol side-chain cleavage enzyme, P450scc, encoded by the CYP11A1 gene. Rare patients with mutations of P450scc are clinically and hormonally indistinguishable from those with lipoid CAH, and may also present as milder non-classic disease. Patients with P450scc defects do not have the massive adrenal hyperplasia that characterizes lipoid CAH, but adrenal imaging may occasionally fail to distinguish these, necessitating DNA sequencing.
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Affiliation(s)
- Walter L Miller
- Center for Reproductive Sciences, University of California, San Francisco, CA 94143-0556, United States.
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17
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Mutemberezi V, Guillemot-Legris O, Muccioli GG. Oxysterols: From cholesterol metabolites to key mediators. Prog Lipid Res 2016; 64:152-169. [PMID: 27687912 DOI: 10.1016/j.plipres.2016.09.002] [Citation(s) in RCA: 234] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 09/13/2016] [Accepted: 09/23/2016] [Indexed: 12/13/2022]
Abstract
Oxysterols are cholesterol metabolites that can be produced through enzymatic or radical processes. They constitute a large family of lipids (i.e. the oxysterome) involved in a plethora of physiological processes. They can act through GPCR (e.g. EBI2, SMO, CXCR2), nuclear receptors (LXR, ROR, ERα) and through transporters or regulatory proteins. Their physiological effects encompass cholesterol, lipid and glucose homeostasis. Additionally, they were shown to be involved in other processes such as immune regulatory functions and brain homeostasis. First studied as precursors of bile acids, they quickly emerged as interesting lipid mediators. Their levels are greatly altered in several pathologies and some oxysterols (e.g. 4β-hydroxycholesterol or 7α-hydroxycholestenone) are used as biomarkers of specific pathologies. In this review, we discuss the complex metabolism and molecular targets (including binding properties) of these bioactive lipids in human and mice. We also discuss the genetic mouse models currently available to interrogate their effects in pathophysiological settings. We also summarize the levels of oxysterols reported in two key organs in oxysterol metabolism (liver and brain), plasma and cerebrospinal fluid. Finally, we consider future opportunities and directions in the oxysterol field in order to gain a better insight and understanding of the complex oxysterol system.
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Affiliation(s)
- Valentin Mutemberezi
- Bioanalysis and Pharmacology of Bioactive Lipids Research Group, Louvain Drug Research Institute, Université catholique de Louvain, Belgium
| | - Owein Guillemot-Legris
- Bioanalysis and Pharmacology of Bioactive Lipids Research Group, Louvain Drug Research Institute, Université catholique de Louvain, Belgium
| | - Giulio G Muccioli
- Bioanalysis and Pharmacology of Bioactive Lipids Research Group, Louvain Drug Research Institute, Université catholique de Louvain, Belgium.
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18
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Intracellular cholesterol transport proteins: roles in health and disease. Clin Sci (Lond) 2016; 130:1843-59. [DOI: 10.1042/cs20160339] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 07/12/2016] [Indexed: 12/13/2022]
Abstract
Effective cholesterol homoeostasis is essential in maintaining cellular function, and this is achieved by a network of lipid-responsive nuclear transcription factors, and enzymes, receptors and transporters subject to post-transcriptional and post-translational regulation, whereas loss of these elegant, tightly regulated homoeostatic responses is integral to disease pathologies. Recent data suggest that sterol-binding sensors, exchangers and transporters contribute to regulation of cellular cholesterol homoeostasis and that genetic overexpression or deletion, or mutations, in a number of these proteins are linked with diseases, including atherosclerosis, dyslipidaemia, diabetes, congenital lipoid adrenal hyperplasia, cancer, autosomal dominant hearing loss and male infertility. This review focuses on current evidence exploring the function of members of the ‘START’ (steroidogenic acute regulatory protein-related lipid transfer) and ‘ORP’ (oxysterol-binding protein-related proteins) families of sterol-binding proteins in sterol homoeostasis in eukaryotic cells, and the evidence that they represent valid therapeutic targets to alleviate human disease.
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19
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Kentala H, Weber-Boyvat M, Olkkonen VM. OSBP-Related Protein Family: Mediators of Lipid Transport and Signaling at Membrane Contact Sites. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 321:299-340. [PMID: 26811291 DOI: 10.1016/bs.ircmb.2015.09.006] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Oxysterol-binding protein (OSBP) and its related protein homologs, ORPs, constitute a conserved family of lipid-binding/transfer proteins (LTPs) expressed ubiquitously in eukaryotes. The ligand-binding domain of ORPs accommodates cholesterol and oxysterols, but also glycerophospholipids, particularly phosphatidylinositol-4-phosphate (PI4P). ORPs have been implicated as intracellular lipid sensors or transporters. Most ORPs carry targeting determinants for the endoplasmic reticulum (ER) and non-ER organelle membrane. ORPs are located and function at membrane contact sites (MCSs), at which ER is closely apposed with other organelle limiting membranes. Such sites have roles in lipid transport and metabolism, control of Ca(2+) fluxes, and signaling events. ORPs are postulated either to transport lipids over MCSs to maintain the distinct lipid compositions of organelle membranes, or to control the activity of enzymes/protein complexes with functions in signaling and lipid metabolism. ORPs may transfer PI4P and another lipid class bidirectionally. Transport of PI4P followed by its hydrolysis would in this model provide the energy for transfer of the other lipid against its concentration gradient. Control of organelle lipid compositions by OSBP/ORPs is important for the life cycles of several pathogenic viruses. Targeting ORPs with small-molecular antagonists is proposed as a new strategy to combat viral infections. Several ORPs are reported to modulate vesicle transport along the secretory or endocytic pathways. Moreover, antagonists of certain ORPs inhibit cancer cell proliferation. Thus, ORPs are LTPs, which mediate interorganelle lipid transport and coordinate lipid signals with a variety of cellular regimes.
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Affiliation(s)
- Henriikka Kentala
- Minerva Foundation Institute for Medical Research, Biomedicum 2U, Helsinki, Finland
| | - Marion Weber-Boyvat
- Minerva Foundation Institute for Medical Research, Biomedicum 2U, Helsinki, Finland
| | - Vesa M Olkkonen
- Minerva Foundation Institute for Medical Research, Biomedicum 2U, Helsinki, Finland
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20
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Kuder CH, Weivoda MM, Zhang Y, Zhu J, Neighbors JD, Wiemer DF, Hohl RJ. 3-Deoxyschweinfurthin B Lowers Cholesterol Levels by Decreasing Synthesis and Increasing Export in Cultured Cancer Cell Lines. Lipids 2015; 50:1195-207. [PMID: 26494560 DOI: 10.1007/s11745-015-4083-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 10/02/2015] [Indexed: 01/12/2023]
Abstract
The schweinfurthins have potent antiproliferative activity in multiple glioblastoma multiforme (GBM) cell lines; however, the mechanism by which growth is impeded is not fully understood. Previously, we demonstrated that the schweinfurthins reduce the level of key isoprenoid intermediates in the cholesterol biosynthetic pathway. Herein, we describe the effects of the schweinfurthins on cholesterol homeostasis. Intracellular cholesterol levels are greatly reduced in cells incubated with 3-deoxyschweinfurthin B (3dSB), an analog of the natural product schweinfurthin B. Decreased cholesterol levels are due to decreased cholesterol synthesis and increased cholesterol efflux; both of these cellular actions can be influenced by liver X-receptor (LXR) activation. The effects of 3dSB on ATP-binding cassette transporter 1 levels and other LXR targets are similar to that of 25-hydroxycholesterol, an LXR agonist. Unlike 25-hydroxycholesterol, 3dSB does not act as a direct agonist for LXR α or β. These data suggest that cholesterol homeostasis plays a significant role in the growth inhibitory activity of the schweinfurthins and may elucidate a mechanism that can be targeted in human cancers such as GBM.
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Affiliation(s)
- Craig H Kuder
- Department of Internal Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - Megan M Weivoda
- Department of Pharmacology, University of Iowa, Iowa City, IA, 52242, USA.,Department of Endocrinology, Mayo Clinic, Rochester, MN, USA
| | - Ying Zhang
- Department of Public Health Sciences, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Junjia Zhu
- Department of Public Health Sciences, Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Jeffrey D Neighbors
- Department of Chemistry, University of Iowa, Iowa City, IA, 52242, USA.,Department of Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - David F Wiemer
- Department of Pharmacology, University of Iowa, Iowa City, IA, 52242, USA.,Department of Chemistry, University of Iowa, Iowa City, IA, 52242, USA
| | - Raymond J Hohl
- Department of Internal Medicine, University of Iowa, Iowa City, IA, 52242, USA. .,Department of Pharmacology, University of Iowa, Iowa City, IA, 52242, USA. .,, Mail Code CH72, 500 University Drive, Hershey, PA, 17033-0850, USA. .,Departments of Medicine and Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA, USA.
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21
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Gulshan K, Smith J. Sphingomyelin regulation of plasma membrane asymmetry, efflux and reverse cholesterol transport. ACTA ACUST UNITED AC 2014. [DOI: 10.2217/clp.14.28] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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22
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Abstract
There is compelling evidence from human population studies that plasma levels of high-density lipoprotein (HDL) cholesterol correlate inversely with cardiovascular risk. Identification of this relationship has stimulated research designed to understand how HDL metabolism is regulated. The ultimate goal of these studies has been to develop HDL-raising therapies that have the potential to decrease the morbidity and mortality associated with atherosclerotic cardiovascular disease. However, the situation has turned out to be much more complex than originally envisaged. This is partly because the HDL fraction consists of multiple subpopulations of particles that vary in terms of shape, size, composition, and surface charge, as well as in their potential cardioprotective properties. This heterogeneity is a consequence of the continual remodeling and interconversion of HDL subpopulations by multiple plasma factors. Evidence that the remodeling of HDLs may impact on their cardioprotective properties is beginning to emerge. This serves to highlight the importance of understanding not only how the remodeling and interconversion of HDL subpopulations is regulated but also how these processes are affected by agents that increase HDL levels. This review provides an overview of what is currently understood about HDL metabolism and how the subpopulation distribution of these lipoproteins is regulated.
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Affiliation(s)
- Kerry-Anne Rye
- From the Lipid Research Group, Centre for Vascular Research, Lowy Center, University of New South Wales, Sydney, New South Wales, Australia
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23
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Hsieh V, Kim MJ, Gelissen IC, Brown AJ, Sandoval C, Hallab JC, Kockx M, Traini M, Jessup W, Kritharides L. Cellular cholesterol regulates ubiquitination and degradation of the cholesterol export proteins ABCA1 and ABCG1. J Biol Chem 2014; 289:7524-36. [PMID: 24500716 DOI: 10.1074/jbc.m113.515890] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The objective of this study was to examine the influence of cholesterol in post-translational control of ABCA1 and ABCG1 protein expression. Using CHO cell lines stably expressing human ABCA1 or ABCG1, we observed that the abundance of these proteins is increased by cell cholesterol loading. The response to increased cholesterol is rapid, is independent of transcription, and appears to be specific for these membrane proteins. The effect is mediated through cholesterol-dependent inhibition of transporter protein degradation. Cell cholesterol loading similarly regulates degradation of endogenously expressed ABCA1 and ABCG1 in human THP-1 macrophages. Turnover of ABCA1 and ABCG1 is strongly inhibited by proteasomal inhibitors and is unresponsive to inhibitors of lysosomal proteolysis. Furthermore, cell cholesterol loading inhibits ubiquitination of ABCA1 and ABCG1. Our findings provide evidence for a rapid, cholesterol-dependent, post-translational control of ABCA1 and ABCG1 protein levels, mediated through a specific and sterol-sensitive mechanism for suppression of transporter protein ubiquitination, which in turn decreases proteasomal degradation. This provides a mechanism for acute fine-tuning of cholesterol transporter activity in response to fluctuations in cell cholesterol levels, in addition to the longer term cholesterol-dependent transcriptional regulation of these genes.
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Affiliation(s)
- Victar Hsieh
- From the Atherosclerosis Laboratory, ANZAC Research Institute and
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24
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Lv YC, Yin K, Fu YC, Zhang DW, Chen WJ, Tang CK. Posttranscriptional Regulation ofATP-Binding Cassette Transporter A1in Lipid Metabolism. DNA Cell Biol 2013; 32:348-58. [DOI: 10.1089/dna.2012.1940] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Affiliation(s)
- Yun-cheng Lv
- Key Laboratory for Atherosclerology of Hunan Province, Institute of Cardiovascular Research, Life Science Research Center, University of South China, Hengyang, China
- Laboratory of Clinical Anatomy, University of South China, Hengyang, China
| | - Kai Yin
- Key Laboratory for Atherosclerology of Hunan Province, Institute of Cardiovascular Research, Life Science Research Center, University of South China, Hengyang, China
| | - Yu-chang Fu
- Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, Alabama
| | - Da-wei Zhang
- Department of Pediatrics and Group on the Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Canada
| | - Wu-jun Chen
- Key Laboratory for Atherosclerology of Hunan Province, Institute of Cardiovascular Research, Life Science Research Center, University of South China, Hengyang, China
| | - Chao-ke Tang
- Key Laboratory for Atherosclerology of Hunan Province, Institute of Cardiovascular Research, Life Science Research Center, University of South China, Hengyang, China
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25
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Protein tyrosine phosphatase inhibition down-regulates ligand-induced ABCA1 expression. Atherosclerosis 2013; 228:362-9. [DOI: 10.1016/j.atherosclerosis.2013.03.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Revised: 02/05/2013] [Accepted: 03/09/2013] [Indexed: 11/22/2022]
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26
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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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27
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Olkkonen VM, Zhou Y, Yan D, Vihervaara T. Oxysterol-binding proteins-emerging roles in cell regulation. EUR J LIPID SCI TECH 2012. [DOI: 10.1002/ejlt.201200044] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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28
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Dushkin MI. Macrophage/foam cell is an attribute of inflammation: Mechanisms of formation and functional role. BIOCHEMISTRY (MOSCOW) 2012; 77:327-38. [DOI: 10.1134/s0006297912040025] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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29
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Oxysterols and their cellular effectors. Biomolecules 2012; 2:76-103. [PMID: 24970128 PMCID: PMC4030866 DOI: 10.3390/biom2010076] [Citation(s) in RCA: 126] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Revised: 02/03/2012] [Accepted: 02/07/2012] [Indexed: 11/23/2022] Open
Abstract
Oxysterols are oxidized 27-carbon cholesterol derivatives or by-products of cholesterol biosynthesis, with a spectrum of biologic activities. Several oxysterols have cytotoxic and pro-apoptotic activities, the ability to interfere with the lateral domain organization, and packing of membrane lipids. These properties may account for their suggested roles in the pathology of diseases such as atherosclerosis, age-onset macular degeneration and Alzheimer’s disease. Oxysterols also have the capacity to induce inflammatory responses and play roles in cell differentiation processes. The functions of oxysterols as intermediates in the synthesis of bile acids and steroid hormones, and as readily transportable forms of sterol, are well established. Furthermore, their actions as endogenous regulators of gene expression in lipid metabolism via liver X receptors and the Insig (insulin-induced gene) proteins have been investigated in detail. The cytoplasmic oxysterol-binding protein (OSBP) homologues form a group of oxysterol/cholesterol sensors that has recently attracted a lot of attention. However, their mode of action is, as yet, poorly understood. Retinoic acid receptor-related orphan receptors (ROR) α and γ, and Epstein-Barr virus induced gene 2 (EBI2) have been identified as novel oxysterol receptors, revealing new physiologic oxysterol effector mechanisms in development, metabolism, and immunity, and evoking enhanced interest in these compounds in the field of biomedicine.
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Allahverdian S, Pannu PS, Francis GA. Contribution of monocyte-derived macrophages and smooth muscle cells to arterial foam cell formation. Cardiovasc Res 2012; 95:165-72. [PMID: 22345306 DOI: 10.1093/cvr/cvs094] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Smooth muscle cells (SMCs) are the main cell type in intimal thickenings and some stages of human atherosclerosis. Like monocyte-derived macrophages, SMCs accumulate excess lipids and contribute to the total intimal foam cell population. In contrast, apolipoprotein (Apo)E-deficient and LDL receptor-deficient mice develop atherosclerotic lesions that are macrophage- as opposed to SMC-rich. The lesser contribution of SMCs to lesion development in these mouse models has distracted attention away from the importance of SMC cholesterol homeostasis in the artery wall. Intimal SMCs accumulate excess amounts of cholesteryl esters when compared with medial layer SMCs, possibly explained by reduced ATP-binding cassette transporter A1 expression and ApoA-I binding to intimal-type SMCs. The aim of this review is to compare the relative contribution of monocyte-derived macrophages and SMCs to human vs. mouse atherosclerosis, and describe what is known about lipid uptake and removal mechanisms contributing to arterial macrophage and SMC foam cell formation. An increased understanding of the contribution of these cell types to lesion development will help to delineate their relative importance in atherogenesis and as potential therapeutic targets.
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Affiliation(s)
- Sima Allahverdian
- Department of Medicine, UBC James Hogg Research Centre, Providence Heart + Lung Institute at St Paul's Hospital, Room 166, Burrard Building, 1081 Burrard Street, Vancouver, BC, Canada V6Z 1Y6
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CHEN WJ, YIN K, ZHAO GJ, TANG CK. microRNAs:A New Mechanisms for Regulation of Lipid Metabolism*. PROG BIOCHEM BIOPHYS 2011. [DOI: 10.3724/sp.j.1206.2011.00072] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Mackrill JJ. Oxysterols and calcium signal transduction. Chem Phys Lipids 2011; 164:488-95. [PMID: 21513705 DOI: 10.1016/j.chemphyslip.2011.04.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Revised: 04/04/2011] [Accepted: 04/06/2011] [Indexed: 12/31/2022]
Abstract
Ionised calcium (Ca(2+)) is a key second messenger, regulating almost every cellular process from cell death to muscle contraction. Cytosolic levels of this ion can be increased via gating of channel proteins located in the plasma membrane, endoplasmic reticulum and other membrane-delimited organelles. Ca(2+) can be removed from cells by extrusion across the plasma membrane, uptake into organelles and buffering by anionic components. Ca(2+) channels and extrusion mechanisms work in concert to generate diverse spatiotemporal patterns of this second messenger, the distinct profiles of which determine different cellular outcomes. Increases in cytoplasmic Ca(2+) concentration are one of the most rapid cellular responses upon exposure to certain oxysterol congeners or to oxidised low-density lipoprotein, occurring within seconds of addition and preceding increases in levels of reactive oxygen species, or changes in gene expression. Furthermore, exposure of cells to oxysterols for periods of hours to days modulates Ca(2+) signal transduction, with these longer-term alterations in cellular Ca(2+) homeostasis potentially underlying pathological events within atherosclerotic lesions, such as hyporeactivity to vasoconstrictors observed in vascular smooth muscle, or ER stress-induced cell death in macrophages. Despite their candidate roles in physiology and disease, little is known about the molecular mechanisms that couple changes in oxysterol concentrations to alterations in Ca(2+) signalling. This review examines the ways in which oxysterols could influence Ca(2+) signal transduction and the potential roles of this in health and disease.
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Affiliation(s)
- John J Mackrill
- Department of Physiology, University College Cork, Cork, Ireland.
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Zhou Y, Li S, Mäyränpää MI, Zhong W, Bäck N, Yan D, Olkkonen VM. OSBP-related protein 11 (ORP11) dimerizes with ORP9 and localizes at the Golgi–late endosome interface. Exp Cell Res 2010; 316:3304-16. [DOI: 10.1016/j.yexcr.2010.06.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Revised: 06/01/2010] [Accepted: 06/07/2010] [Indexed: 11/30/2022]
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Abstract
Oxysterol-binding protein (OSBP)-related proteins (ORPs) are lipid-binding proteins that are conserved from yeast to humans. They are implicated in many cellular processes including signaling, vesicular trafficking, lipid metabolism, and nonvesicular sterol transport. All ORPs contain an OSBP-related domain (ORD) that has a hydrophobic pocket that binds a single sterol. ORDs also contain additional membrane-binding surfaces, some of which bind phosphoinositides and may regulate sterol binding. Studies in yeast suggest that ORPs function as sterol transporters, perhaps in regions where organelle membranes are closely apposed. Yeast ORPs also participate in vesicular trafficking, although their role is unclear. In mammalian cells, some ORPs function as sterol sensors that regulate the assembly of protein complexes in response to changes in cholesterol levels. This review will summarize recent advances in our understanding of how ORPs bind lipids and membranes and how they function in diverse cellular processes.
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Affiliation(s)
- Sumana Raychaudhuri
- Laboratory of Cell Biochemistry and Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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Banerji S, Ngo M, Lane CF, Robinson CA, Minogue S, Ridgway ND. Oxysterol binding protein-dependent activation of sphingomyelin synthesis in the golgi apparatus requires phosphatidylinositol 4-kinase IIα. Mol Biol Cell 2010; 21:4141-50. [PMID: 20881054 PMCID: PMC2993743 DOI: 10.1091/mbc.e10-05-0424] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The study identifies a sterol- and oxysterol binding protein (OSBP)-regulated phosphatidylinositol 4-kinase that regulates ceramide transport protein (CERT) activity and sphingomyelin (SM) synthesis. RNA interference silencing experiments identify PI4KIIα; as the mediator of Golgi recruitment of CERT, providing a potential mechanism for coordinating assembly of SM and cholesterol in the Golgi or more distal compartments. Cholesterol and sphingomyelin (SM) associate in raft domains and are metabolically coregulated. One aspect of coordinate regulation occurs in the Golgi apparatus where oxysterol binding protein (OSBP) mediates sterol-dependent activation of ceramide transport protein (CERT) activity and SM synthesis. Because CERT transfer activity is dependent on its phosphatidylinositol 4 phosphate [PtdIns(4)P]-specific pleckstrin homology domain, we investigated whether OSBP activation of CERT involved a Golgi-associated PtdIns 4-kinase (PI4K). Cell fractionation experiments revealed that Golgi/endosome-enriched membranes from 25-hydroxycholesterol-treated Chinese hamster ovary cells had increased activity of a sterol-sensitive PI4K that was blocked by small interfering RNA silencing of OSBP. Consistent with this sterol-requirement, OSBP silencing also reduced the cholesterol content of endosome/trans-Golgi network (TGN) fractions containing PI4KIIα. PI4KIIα, but not PI4KIIIβ, was required for oxysterol-activation of SM synthesis and recruitment of CERT to the Golgi apparatus. However, neither PI4KIIα nor PI4KIIIβ expression was required for 25-hydroxycholesterol–dependent translocation of OSBP to the Golgi apparatus. The presence of OSBP, CERT, and PI4KIIα in the TGN of oxysterol-stimulated cells suggests that OSBP couples sterol binding or transfer activity with regulation of PI4KIIα activity, leading to CERT recruitment to the TGN and increased SM synthesis.
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Affiliation(s)
- Sangeeta Banerji
- Departments of Pediatrics and Biochemistry and Molecular Biology, Atlantic Research Centre, Dalhousie University, Halifax, NS, Canada
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Functional implications of sterol transport by the oxysterol-binding protein gene family. Biochem J 2010; 429:13-24. [PMID: 20545625 DOI: 10.1042/bj20100263] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Cholesterol and its numerous oxygenated derivatives (oxysterols) profoundly affect the biophysical properties of membranes, and positively and negatively regulate sterol homoeostasis through interaction with effector proteins. As the bulk of cellular sterols are segregated from the sensory machinery that controls homoeostatic responses, an important regulatory step involves sterol transport or signalling between membrane compartments. Evidence for rapid, energy-independent transport between organelles has implicated transport proteins, such as the eukaryotic family of OSBP (oxysterol-binding protein)/ORPs (OSBP-related proteins). Since the founding member of this family was identified more than 25 years ago, accumulated evidence has implicated OSBP/ORPs in sterol signalling and/or sterol transport functions. However, recent evidence of sterol transfer activity by OSBP/ORPs suggests that other seemingly disparate functions could be the result of alterations in membrane sterol distribution or ancillary to this primary activity.
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Field FJ, Watt K, Mathur SN. TNF-alpha decreases ABCA1 expression and attenuates HDL cholesterol efflux in the human intestinal cell line Caco-2. J Lipid Res 2010; 51:1407-15. [PMID: 20103810 DOI: 10.1194/jlr.m002410] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
HDL cholesterol levels are decreased in Crohn's disease, a tumor necrosis factor-alpha (TNF-alpha)-driven chronic inflammatory condition involving the gastrointestinal tract. ATP-binding cassette transporter A1 (ABCA1), one of several liver X receptor (LXR) target genes, is a cell surface transporter that mediates the rate-controlling step in HDL synthesis. The regulation of ABCA1 and HDL cholesterol efflux by TNF-alpha was investigated in the human intestinal cell line Caco-2. In response to cholesterol micelles or T0901317, an LXR nonsterol agonist, TNF-alpha decreased the basolateral efflux of cholesterol to apolipoprotein A1 (apoA1). TNF-alpha, by attenuating ABCA1 promoter activity, markedly decreased ABCA1 gene expression without attenuating the expression of LXR-alpha, LXR-beta, and most other LXR target genes, such as ABCG1, FAS, ABCG8, scavenger receptor-B1 (SR-B1), and apoC1. TNF-alpha also decreased ABCA1 mass by markedly enhancing the rate of ABCA1 degradation and modestly inhibiting its rate of synthesis. Inhibitors of the nuclear factor-kappaB (NF-kappaB) pathway, which is activated by TNF-alpha, partially reverse the effect of TNF-alpha on ABCA1 protein expression. The results suggest that TNF-alpha, the major cytokine implicated in the inflammation of Crohn's disease, decreases HDL cholesterol levels by attenuating the expression of intestinal ABCA1 and cholesterol efflux to apoA1.
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Affiliation(s)
- F Jeffrey Field
- Department of Internal, Medicine University of Iowa, Iowa City, IA 52242, USA. f-jeffrey-fi
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Fitzgerald ML, Mujawar Z, Tamehiro N. ABC transporters, atherosclerosis and inflammation. Atherosclerosis 2010; 211:361-70. [PMID: 20138281 DOI: 10.1016/j.atherosclerosis.2010.01.011] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Revised: 01/06/2010] [Accepted: 01/07/2010] [Indexed: 10/19/2022]
Abstract
Atherosclerosis, driven by inflamed lipid-laden lesions, can occlude the coronary arteries and lead to myocardial infarction. This chronic disease is a major and expensive health burden. However, the body is able to mobilize and excrete cholesterol and other lipids, thus preventing atherosclerosis by a process termed reverse cholesterol transport (RCT). Insight into the mechanism of RCT has been gained by the study of two rare syndromes caused by the mutation of ABC transporter loci. In Tangier disease, loss of ABCA1 prevents cells from exporting cholesterol and phospholipid, thus resulting in the build-up of cholesterol in the peripheral tissues and a loss of circulating HDL. Consistent with HDL being an athero-protective particle, Tangier patients are more prone to develop atherosclerosis. Likewise, sitosterolemia is another inherited syndrome associated with premature atherosclerosis. Here mutations in either the ABCG5 or G8 loci, prevents hepatocytes and enterocytes from excreting cholesterol and plant sterols, including sitosterol, into the bile and intestinal lumen. Thus, ABCG5 and G8, which from a heterodimer, constitute a transporter that excretes cholesterol and dietary sterols back into the gut, while ABCA1 functions to export excess cell cholesterol and phospholipid during the biogenesis of HDL. Interestingly, a third protein, ABCG1, that has been shown to have anti-atherosclerotic activity in mice, may also act to transfer cholesterol to mature HDL particles. Here we review the relationship between the lipid transport activities of these proteins and their anti-atherosclerotic effect, particularly how they may reduce inflammatory signaling pathways. Of particular interest are recent reports that indicate both ABCA1 and ABCG1 modulate cell surface cholesterol levels and inhibit its partitioning into lipid rafts. Given lipid rafts may provide platforms for innate immune receptors to respond to inflammatory signals, it follows that loss of ABCA1 and ABCG1 by increasing raft content will increase signaling through these receptors, as has been experimentally demonstrated. Moreover, additional reports indicate ABCA1, and possibly SR-BI, another HDL receptor, may directly act as anti-inflammatory receptors independent of their lipid transport activities. Finally, we give an update on the progress and pitfalls of therapeutic approaches that seek to stimulate the flux of lipids through the RCT pathway.
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Affiliation(s)
- Michael L Fitzgerald
- Lipid Metabolism Unit, Massachusetts General Hospital, Harvard Medical School, 185 Cambridge Street, Boston, MA 02114, USA.
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Martins IJ, Berger T, Sharman MJ, Verdile G, Fuller SJ, Martins RN. Cholesterol metabolism and transport in the pathogenesis of Alzheimer's disease. J Neurochem 2010; 111:1275-308. [PMID: 20050287 DOI: 10.1111/j.1471-4159.2009.06408.x] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Alzheimer's disease (AD) is the most common neurodegenerative disorder, affecting millions of people worldwide. Apart from age, the major risk factor identified so far for the sporadic form of AD is possession of the epsilon4 allele of apolipoprotein E (APOE), which is also a risk factor for coronary artery disease (CAD). Other apolipoproteins known to play an important role in CAD such as apolipoprotein B are now gaining attention for their role in AD as well. AD and CAD share other risk factors, such as altered cholesterol levels, particularly high levels of low density lipoproteins together with low levels of high density lipoproteins. Statins--drugs that have been used to lower cholesterol levels in CAD, have been shown to protect against AD, although the protective mechanism(s) involved are still under debate. Enzymatic production of the beta amyloid peptide, the peptide thought to play a major role in AD pathogenesis, is affected by membrane cholesterol levels. In addition, polymorphisms in several proteins and enzymes involved in cholesterol and lipoprotein transport and metabolism have been linked to risk of AD. Taken together, these findings provide strong evidence that changes in cholesterol metabolism are intimately involved in AD pathogenic processes. This paper reviews cholesterol metabolism and transport, as well as those aspects of cholesterol metabolism that have been linked with AD.
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Affiliation(s)
- Ian J Martins
- Centre of Excellence for Alzheimer's Disease Research and Care, Edith Cowan University, Joondalup, Australia.
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Abstract
In eukaryotic cells, membranes of the late secretory pathway contain a disproportionally large amount of cholesterol in relation to the endoplasmic reticulum, nuclear envelope and mitochondria. At one extreme, enrichment of the plasma membrane with cholesterol and sphingolipids is crucial for formation of liquid ordered domains (rafts) involved in cell communication and transport. On the other hand, regulatory machinery in the endoplasmic reticulum is maintained in a relatively cholesterol-poor environment, to ensure appropriate rapid responses to fluctuations in cellular sterol levels. Thus, cholesterol homeostasis is absolutely dependent on its distribution along an intracellular gradient. It is apparent that this gradient is maintained by a combination of sterol-lipid interactions, vesicular transport and sterol-binding/transport proteins. Evidence for rapid, energy-independent transport between organelles has implicated transport proteins, in particular the eukaryotic oxysterol binding protein (OSBP) family. Since the founding member of this family was identified more than 25 years ago, accumulated evidence implicates the 12-member family of OSBP and OSBP-related proteins (ORPs) in sterol signalling and/or sterol transport functions. The OSBP/ORP gene family is characterized by a conserved beta-barrel sterol-binding fold but is differentiated from other sterol-binding proteins by the presence of additional domains that target multiple organelle membranes. Here we will discuss the functional and structural characteristics of the mammalian OSBP/ORP family that support a 'dual-targeting' model for sterol transport between membranes.
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Affiliation(s)
- Neale D Ridgway
- Department of Pediatrics, Dalhousie University, Halifax, Nova Scotia, B3H 4H7, Canada.
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Affiliation(s)
- Norihito Shibata
- Department of Cellular and Molecular Medicine, University of California
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Weibel GL, Joshi MR, Alexander ET, Zhu P, Blair IA, Rothblat GH. Overexpression of human 15(S)-lipoxygenase-1 in RAW macrophages leads to increased cholesterol mobilization and reverse cholesterol transport. Arterioscler Thromb Vasc Biol 2009; 29:837-42. [PMID: 19325142 DOI: 10.1161/atvbaha.109.186163] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE The purpose of this study was to determine the effect of 15-lipoxygenase-1 (15-LO-1) on cholesterol mobilization from macrophages. METHODS AND RESULTS Overexpression of human 15-LO-1 in RAW mouse macrophages led to enhanced cholesterol efflux, increased cholesteryl ester (CE) hydrolysis, and increased reverse cholesterol transport (RCT). Efflux studies comparing 15-LO-1 overexpressing cells to mock-transfected RAW macrophages resulted in a 3- to 7-fold increase in cholesterol efflux to apolipoprotein A-I and a modest increase in efflux to HDL. Additional experiments revealed an increase in mRNA and protein levels of ABCA1 and ABCG1 in the RAW expressing 15-LO-1 compared to controls. Efforts to examine whether the arachidonic acid metabolite of 15-LO-1, (15S)-hydroxyeicosatetraenoic acid (HETE), was responsible for the enhanced efflux revealed this eicosanoid metabolite did not play a role. Enhanced steryl ester hydrolysis was observed in 15-LO-1 overexpressing cells suggesting that the CE produced in the 15-LO-1 expressing cells was readily mobilized. To measure RCT, RAW macrophages overexpressing 15-LO-1 or mock-transfected cells were cholesterol enriched by exposure to acetylated low-density lipoprotein and [(3)H]-cholesterol. These macrophages were injected into wild-type animals and RCT was measured as a percent of injected dose of (3)H appearing in the feces at 48 hours. We found 7% of the injected (3)H in the feces of mice that received macrophages overexpressing 15-LO-1 and 4% in the feces of mice that received mock-transfected cells. CONCLUSIONS These data are consistent with a model in which overexpression of human 15-LO-1 in RAW macrophages promotes RCT through increased CE hydrolysis and ABCA1-mediated cholesterol efflux.
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Affiliation(s)
- Ginny L Weibel
- Division of Gastroenterology and Nutrition, The Children's Hospital of Philadelphia, 3615 Civic Center Blvd, ARC1102, Philadelphia, PA 19104-4399, USA.
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Mattjus P. Glycolipid transfer proteins and membrane interaction. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1788:267-72. [PMID: 19007748 DOI: 10.1016/j.bbamem.2008.10.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2008] [Revised: 10/07/2008] [Accepted: 10/07/2008] [Indexed: 12/17/2022]
Abstract
The glycolipid transfer protein is found from animals and fungi to plants and red micro-alga. Some eukaryotes that do not encode the glucosylceramide synthase like the yeast Schizosaccharomyces pombe and Saccharomyces cerevisiae do neither produce glycolipid transfer like proteins. On the other hand yeast like Eremothecium gossypii that do synthesize glucosylceramide also express glycolipid transfer protein. Based on this novel genetic relationship it is not far fetched to assume that there must be a strong correlation between the synthesis of the glycolipid precursor and the glycolipid transfer protein. Because the glycolipid transfer protein is localized in the cytosol it is unlikely that it would participate in events associated with lipid rafts or caveolar structures, since they are found on the outer leaflet of the plasma membrane. Rather, GLTP is likely to be involved in events at the cytosolic side of the plasma membrane or the endoplasmic reticulum, maybe function as a reporter or sensor of glycolipid levels. A similar function has been proposed for other proteins with affinity for lipids like the oxysterol binding proteins and phosphatidylinositol transfer proteins that are thought to be able act as lipid sensors. Recent discoveries in the glycolipid transfer protein field are discussed.
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Affiliation(s)
- Peter Mattjus
- Department of Biochemistry and Pharmacy, Abo Akademi University, Turku, Finland.
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Abstract
PURPOSE OF REVIEW The lipid efflux pathway is important for both HDL formation and the reverse cholesterol transport pathway. This review is focused on recent findings on the mechanism of lipid efflux and its regulation, particularly in macrophages. RECENT FINDINGS Significant progress has been made on understanding the sequence of events that accompany the interaction of apolipoproteins A-I with cell surface ATP-binding cassette transporter A1 and its subsequent lipidation. Continued research on the regulation of ATP-binding cassette transporter A1 and ATP-binding cassette transporter G1 expression and traffic has also generated new paradigms for the control of lipid efflux from macrophages and its contribution to reverse cholesterol transport. In addition, the mobilization of cholesteryl esters from lipid droplets represents a new step in the control of cholesterol efflux. SUMMARY The synergy between lipid transporters is a work in progress, but its importance in reverse cholesterol transport is clear. The regulation of efflux implies both the regulation of relevant transporters and the cellular trafficking of cholesterol.
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Affiliation(s)
- Yves L Marcel
- Lipoprotein and Atherosclerosis Research Group, University of Ottawa Heart Institute, Ottawa, Ontario, Canada.
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