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Mullis DM, Padilla-Lopez A, Wang H, Zhu Y, Elde S, Bonham SA, Yajima S, Kocher ON, Krieger M, Woo YJ. Stromal cell-derived factor-1 alpha improves cardiac function in a novel diet-induced coronary atherosclerosis model, the SR-B1ΔCT/LDLR KO mouse. Atherosclerosis 2024; 395:117518. [PMID: 38627162 PMCID: PMC11254567 DOI: 10.1016/j.atherosclerosis.2024.117518] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Revised: 02/28/2024] [Accepted: 03/12/2024] [Indexed: 06/13/2024]
Abstract
BACKGROUND AND AIMS There are a limited number of pharmacologic therapies for coronary artery disease, and few rodent models of occlusive coronary atherosclerosis and consequent myocardial infarction with which one can rapidly test new therapeutic approaches. Here, we characterize a novel, fertile, and easy-to-use HDL receptor (SR-B1)-based model of atherogenic diet-inducible, fatal coronary atherosclerosis, the SR-B1ΔCT/LDLR KO mouse. Additionally, we test intramyocardial injection of Stromal Cell-Derived Factor-1 alpha (SDF-1α), a potent angiogenic cytokine, as a possible therapy to rescue cardiac function in this mouse. METHODS SR-B1ΔCT/LDLR KO mice were fed the Paigen diet or standard chow diet, and we determined the effects of the diets on cardiac function, histology, and survival. After two weeks of feeding either the Paigen diet (n = 24) or standard chow diet (n = 20), the mice received an intramyocardial injection of either SDF-1α or phosphate buffered saline (PBS). Cardiac function and angiogenesis were assessed two weeks later. RESULTS When six-week-old mice were fed the Paigen diet, they began to die as early as 19 days later and 50% had died by 38 days. None of the mice maintained on the standard chow diet died by day 72. Hearts from mice on the Paigen diet showed evidence of cardiomegaly, myocardial infarction, and occlusive coronary artery disease. For the five mice that survived until day 28 that underwent an intramyocardial injection of PBS on day 15, the average ejection fraction (EF) decreased significantly from day 14 (the day before injection, 52.1 ± 4.3%) to day 28 (13 days after the injection, 30.6 ± 6.8%) (paired t-test, n = 5, p = 0.0008). Of the 11 mice fed the Paigen diet and injected with SDF-1α on day 15, 8 (72.7%) survived to day 28. The average EF for these 8 mice increased significantly from 48.2 ± 7.2% on day 14 to63.6 ± 6.9% on day 28 (Paired t-test, n = 8, p = 0.003). CONCLUSIONS This new mouse model and treatment with the promising angiogenic cytokine SDF-1α may lead to new therapeutic approaches for ischemic heart disease.
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MESH Headings
- Animals
- Chemokine CXCL12/metabolism
- Chemokine CXCL12/genetics
- Disease Models, Animal
- Mice, Knockout
- Coronary Artery Disease
- Receptors, LDL/genetics
- Receptors, LDL/deficiency
- Scavenger Receptors, Class B/genetics
- Male
- Neovascularization, Physiologic/drug effects
- Mice, Inbred C57BL
- Diet, Atherogenic
- Mice
- Ventricular Function, Left
- Myocardium/pathology
- Myocardium/metabolism
- Diet, High-Fat
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Affiliation(s)
- Danielle M Mullis
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | | | - Hanjay Wang
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Yuanjia Zhu
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA; Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Stefan Elde
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Spencer A Bonham
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Shin Yajima
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Olivier N Kocher
- Department of Pathology, Beth Israel Hospital, Harvard Medical School, Boston, MA, USA
| | - Monty Krieger
- Department of Biology, Massachusetts Institute of Technology, MA, USA
| | - Y Joseph Woo
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA; Department of Bioengineering, Stanford University, Stanford, CA, USA.
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2
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Claessen MJAG, Yagci N, Fu K, Brandsma E, Kersten MJ, von Lindern M, van den Akker E. Production and stability of cultured red blood cells depends on the concentration of cholesterol in culture medium. Sci Rep 2024; 14:15592. [PMID: 38971841 PMCID: PMC11227516 DOI: 10.1038/s41598-024-66440-z] [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: 04/22/2024] [Accepted: 07/01/2024] [Indexed: 07/08/2024] Open
Abstract
The production of cultured red blood cells (cRBC) for transfusion purposes requires large scale cultures and downstream processes to purify enucleated cRBC. The membrane composition, and cholesterol content in particular, are important during proliferation of (pro)erythroblasts and for cRBC quality. Therefore, we tested the requirement for cholesterol in the culture medium during expansion and differentiation of erythroid cultures with respect to proliferation, enucleation and purification by filtration. The low cholesterol level (22 µg/dl) in serum free medium was sufficient to expand (pro)erythroblast cultures. Addition of 2.0 or 5.0 mg/dL of free cholesterol at the start of differentiation induction inhibited enucleation compared to the default condition containing 3.3 mg/dl total cholesterol derived from the addition of Omniplasma to serum free medium. Addition of 5.0 mg/dl cholesterol at day 5 of differentiation did not affect the enucleation process but significantly increased recovery of enucleated cRBC following filtration over leukodepletion filters. The addition of cholesterol at day 5 increased the osmotic resistance of cRBC. In conclusion, cholesterol supplementation after the onset of enucleation improved the robustness of cRBC and increased the yield of enucleated cRBC in the purification process.
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Affiliation(s)
- M J A G Claessen
- Department Research, Sanquin Blood Supply, Plesmanlaan 125, 1066 CX, Amsterdam, The Netherlands
- Department of Hematology, Amsterdam University Medical Centers, Cancer Center Amsterdam, De Boelelaan 1117, 1081HV, Amsterdam, The Netherlands
- Landsteiner Laboratory, Amsterdam University Medical Center, Plesmanlaan 125, 1066 CX, Amsterdam, The Netherlands
| | - N Yagci
- Department Research, Sanquin Blood Supply, Plesmanlaan 125, 1066 CX, Amsterdam, The Netherlands
- Landsteiner Laboratory, Amsterdam University Medical Center, Plesmanlaan 125, 1066 CX, Amsterdam, The Netherlands
| | - K Fu
- Department Research, Sanquin Blood Supply, Plesmanlaan 125, 1066 CX, Amsterdam, The Netherlands
- Landsteiner Laboratory, Amsterdam University Medical Center, Plesmanlaan 125, 1066 CX, Amsterdam, The Netherlands
| | - E Brandsma
- Department Research, Sanquin Blood Supply, Plesmanlaan 125, 1066 CX, Amsterdam, The Netherlands
- Department of Life Sciences, Saxion University of Applied Sciences, M.H. Tromplaan 28, 7513AB, Enschede, The Netherlands
| | - M J Kersten
- Department of Hematology, Amsterdam University Medical Centers, Cancer Center Amsterdam, De Boelelaan 1117, 1081HV, Amsterdam, The Netherlands
| | - M von Lindern
- Department Research, Sanquin Blood Supply, Plesmanlaan 125, 1066 CX, Amsterdam, The Netherlands
- Landsteiner Laboratory, Amsterdam University Medical Center, Plesmanlaan 125, 1066 CX, Amsterdam, The Netherlands
| | - E van den Akker
- Department Research, Sanquin Blood Supply, Plesmanlaan 125, 1066 CX, Amsterdam, The Netherlands.
- Landsteiner Laboratory, Amsterdam University Medical Center, Plesmanlaan 125, 1066 CX, Amsterdam, The Netherlands.
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3
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Gillard BK, Rosales C, Gotto AM, Pownall HJ. The pathophysiology of excess plasma-free cholesterol. Curr Opin Lipidol 2023; 34:278-286. [PMID: 37732779 PMCID: PMC10624414 DOI: 10.1097/mol.0000000000000899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 09/22/2023]
Abstract
PURPOSE OF REVIEW Several large studies have shown increased mortality due to all-causes and to atherosclerotic cardiovascular disease. In most clinical settings, plasma HDL-cholesterol is determined as a sum of free cholesterol and cholesteryl ester, two molecules with vastly different metabolic itineraries. We examine the evidence supporting the concept that the pathological effects of elevations of plasma HDL-cholesterol are due to high levels of the free cholesterol component of HDL-C. RECENT FINDINGS In a small population of humans, a high plasma HDL-cholesterol is associated with increased mortality. Similar observations in the HDL-receptor deficient mouse (Scarb1 -/- ), a preclinical model of elevated HDL-C, suggests that the pathological component of HDL in these patients is an elevated plasma HDL-FC. SUMMARY Collective consideration of the human and mouse data suggests that clinical trials, especially in the setting of high plasma HDL, should measure free cholesterol and cholesteryl esters and not just total cholesterol.
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Affiliation(s)
- Baiba K. Gillard
- Center for Bioenergetics, Houston Methodist, Houston, Texas
- Weill Cornell Medicine, New York, New York, USA
| | - Corina Rosales
- Center for Bioenergetics, Houston Methodist, Houston, Texas
- Weill Cornell Medicine, New York, New York, USA
| | - Antonio M. Gotto
- Center for Bioenergetics, Houston Methodist, Houston, Texas
- Weill Cornell Medicine, New York, New York, USA
| | - Henry J. Pownall
- Center for Bioenergetics, Houston Methodist, Houston, Texas
- Weill Cornell Medicine, New York, New York, USA
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Wang Z, Yelamanchili D, Liu J, Gotto AM, Rosales C, Gillard BK, Pownall HJ. Serum opacity factor normalizes erythrocyte morphology in Scarb1 -/- mice in an HDL-free cholesterol-dependent way. J Lipid Res 2023; 64:100456. [PMID: 37821077 PMCID: PMC10641538 DOI: 10.1016/j.jlr.2023.100456] [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: 08/09/2023] [Revised: 09/16/2023] [Accepted: 10/05/2023] [Indexed: 10/13/2023] Open
Abstract
Compared with WT mice, HDL receptor-deficient (Scarb1-/-) mice have higher plasma levels of free cholesterol (FC)-rich HDL and exhibit multiple pathologies associated with a high mol% FC in ovaries, platelets, and erythrocytes, which are reversed by lowering HDL. Bacterial serum opacity factor (SOF) catalyzes the opacification of plasma by targeting and quantitatively converting HDL to neo HDL (HDL remnant), a cholesterol ester-rich microemulsion, and lipid-free APOA1. SOF delivery with an adeno-associated virus (AAVSOF) constitutively lowers plasma HDL-FC and reverses female infertility in Scarb1-/- mice in an HDL-dependent way. We tested whether AAVSOF delivery to Scarb1-/- mice will normalize erythrocyte morphology in an HDL-FC-dependent way. We determined erythrocyte morphology and FC content (mol%) in three groups-WT, untreated Scarb1-/- (control), and Scarb1-/- mice receiving AAVSOF-and correlated these with their respective HDL-mol% FC. Plasma-, HDL-, and tissue-lipid compositions were also determined. Plasma- and HDL-mol% FC positively correlated across all groups. Among Scarb1-/- mice, AAVSOF treatment normalized reticulocyte number, erythrocyte morphology, and erythrocyte-mol% FC. Erythrocyte-mol% FC positively correlated with HDL-mol% FC and with both the number of reticulocytes and abnormal erythrocytes. AAVSOF treatment also reduced FC of extravascular tissues to a lesser extent. HDL-FC spontaneously transfers from plasma HDL to cell membranes. AAVSOF treatment lowers erythrocyte-FC and normalizes erythrocyte morphology and lipid composition by reducing HDL-mol% FC.
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Affiliation(s)
- Ziyi Wang
- Center for Bioenergetics, Houston Methodist, Houston, TX, USA; Departments of Endocrinology and Xiangya Hospital, Central South University, Changsha, China
| | | | - Jing Liu
- Center for Bioenergetics, Houston Methodist, Houston, TX, USA; Departments of Endocrinology and Cardiovascular Medicine, Xiangya Hospital, Central South University, Changsha, China
| | - Antonio M Gotto
- Center for Bioenergetics, Houston Methodist, Houston, TX, USA; Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Corina Rosales
- Center for Bioenergetics, Houston Methodist, Houston, TX, USA; Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Baiba K Gillard
- Center for Bioenergetics, Houston Methodist, Houston, TX, USA; Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Henry J Pownall
- Center for Bioenergetics, Houston Methodist, Houston, TX, USA; Department of Medicine, Weill Cornell Medicine, New York, NY, USA.
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5
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Staršíchová A. SR-B1-/-ApoE-R61h/h Mice Mimic Human Coronary Heart Disease. Cardiovasc Drugs Ther 2023:10.1007/s10557-023-07475-8. [PMID: 37273155 DOI: 10.1007/s10557-023-07475-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/22/2023] [Indexed: 06/06/2023]
Abstract
Cardiovascular diseases are the leading cause of death in the modern world. Atherosclerosis underlies the majority of these pathologies and may result in sudden life-threatening events such as myocardial infarction or stroke. Current concepts consider a rupture (resp. erosion) of "unstable/vulnerable" atherosclerotic plaques as a primary cause leading to thrombus formation and subsequent occlusion of the artery lumen finally triggering an acute clinical event. We and others described SR-B1-/-ApoE-R61h/h mice mimicking clinical coronary heart disease in all major aspects: from coronary atherosclerosis through vulnerable plaque ruptures leading to thrombus formation/coronary artery occlusion, finally resulting in myocardial infarction/ischemia. SR-B1-/-ApoE-R61h/h mouse provides a valuable model to study vulnerable/occlusive plaques, to evaluate bioactive compounds as well as new anti-inflammatory and "anti-rupture" drugs, and to test new technologies in experimental cardiovascular medicine. This review summarizes and discuss our knowledge about SR-B1-/-ApoE-R61h/h mouse model based on recent publications and experimental observations from the lab.
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Affiliation(s)
- Andrea Staršíchová
- Graduate School Cell Dynamics and Disease, University of Muenster, Muenster, Germany.
- European Institute for Molecular Imaging, University of Muenster, Muenster, Germany.
- Novogenia Covid GmbH, Eugendorf, Austria.
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6
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Zhang H, Wan GZ, Wang YY, Chen W, Guan JZ. The role of erythrocytes and erythroid progenitor cells in tumors. Open Life Sci 2022; 17:1641-1656. [PMID: 36567722 PMCID: PMC9755711 DOI: 10.1515/biol-2022-0102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 05/09/2022] [Accepted: 05/30/2022] [Indexed: 12/23/2022] Open
Abstract
In the current research context of precision treatment of malignant tumors, the advantages of immunotherapy are unmatched by conventional antitumor therapy, which can prolong progression-free survival and overall survival. The search for new targets and novel combination therapies can improve the efficacy of immunotherapy and reduce adverse effects. Since current research targets for immunotherapy mainly focus on lymphocytes, little research has been done on erythrocytes. Nucleated erythroid precursor stem cells have been discovered to play an essential role in tumor progression. Researchers are exploring new targets and therapeutic approaches for immunotherapy from the perspective of erythroid progenitor cells (EPCs). Recent studies have shown that different subtypes of EPCs have specific surface markers and distinct biological roles in tumor immunity. CD45+ EPCs are potent myeloid-derived suppressor cell-like immunosuppressants that reduce the patient's antitumor immune response. CD45- EPCs promote tumor invasion and metastasis by secreting artemin. A specific type of EPC also promotes angiogenesis and provides radiation protection. Therefore, EPCs may be involved in tumor growth, infiltration, and metastasis. It may also be an important cause of anti-angiogenesis and immunotherapy resistance. This review summarizes recent research advances in erythropoiesis, EPC features, and their impacts and processes on tumors.
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Affiliation(s)
- Hao Zhang
- Department of Oncology, The Fifth Medical Center, Chinese PLA (People’s Liberation Army) General Hospital, Beijing 100091, China,Department of Oncology, The Eighth Medical Center, Chinese PLA (People’s Liberation Army) General Hospital, Beijing 100071, China,Postgraduate Department of Hebei North University, Zhangjiakou 075000, China
| | - Guang-zhi Wan
- Department of Oncology, The Eighth Medical Center, Chinese PLA (People’s Liberation Army) General Hospital, Beijing 100071, China
| | - Yu-ying Wang
- Department of Oncology, First Medical Center, Chinese PLA (People’s Liberation Army) General Hospital, Beijing, China
| | - Wen Chen
- Department of Pathology, The Eighth Medical Center, Chinese PLA (People’s Liberation Army) General Hospital, Beijing 100091, China
| | - Jing-Zhi Guan
- Department of Oncology, The Eighth Medical Center, Chinese PLA (People’s Liberation Army) General Hospital, Beijing 100071, China
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7
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Liu T, Qu J, Tian M, Yang R, Song X, Li R, Yan J, Qiao J. Lipid Metabolic Process Involved in Oocyte Maturation During Folliculogenesis. Front Cell Dev Biol 2022; 10:806890. [PMID: 35433675 PMCID: PMC9009531 DOI: 10.3389/fcell.2022.806890] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 03/03/2022] [Indexed: 11/25/2022] Open
Abstract
Oocyte maturation is a complex and dynamic process regulated by the coordination of ovarian cells and numerous extraovarian signals. From mammal studies, it is learnt that lipid metabolism provides sufficient energy for morphological and cellular events during folliculogenesis, and numerous lipid metabolites, including cholesterol, lipoproteins, and 14-demethyl-14-dehydrolanosterol, act as steroid hormone precursors and meiotic resumption regulators. Endogenous and exogenous signals, such as gonadotropins, insulin, and cortisol, are the upstream regulators in follicular lipid metabolic homeostasis, forming a complex and dynamic network in which the key factor or pathway that plays the central role is still a mystery. Though lipid metabolites are indispensable, long-term exposure to a high-fat environment will induce irreversible damage to follicular cells and oocyte meiosis. This review specifically describes the transcriptional expression patterns of several lipid metabolism–related genes in human oocytes and granulosa cells during folliculogenesis, illustrating the spatiotemporal lipid metabolic changes in follicles and the role of lipid metabolism in female reproductive capacity. This study aims to elaborate the impact of lipid metabolism on folliculogenesis, thus providing guidance for improving the fertility of obese women and the clinical outcome of assisted reproduction.
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Affiliation(s)
- Tao Liu
- Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
- National Clinical Research Center for Obstetrics and Gynecology, Beijing, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproduction, Beijing, China
- Research Units of Comprehensive Diagnosis and Treatment of Oocyte Maturation Arrest, Chinese Academy of Medical Sciences, Beijing, China
| | - Jiangxue Qu
- Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
- National Clinical Research Center for Obstetrics and Gynecology, Beijing, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproduction, Beijing, China
- Research Units of Comprehensive Diagnosis and Treatment of Oocyte Maturation Arrest, Chinese Academy of Medical Sciences, Beijing, China
| | - Mengyuan Tian
- Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
- National Clinical Research Center for Obstetrics and Gynecology, Beijing, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproduction, Beijing, China
- Research Units of Comprehensive Diagnosis and Treatment of Oocyte Maturation Arrest, Chinese Academy of Medical Sciences, Beijing, China
| | - Rui Yang
- Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
- National Clinical Research Center for Obstetrics and Gynecology, Beijing, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproduction, Beijing, China
- Research Units of Comprehensive Diagnosis and Treatment of Oocyte Maturation Arrest, Chinese Academy of Medical Sciences, Beijing, China
| | - Xueling Song
- Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
- National Clinical Research Center for Obstetrics and Gynecology, Beijing, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproduction, Beijing, China
- Research Units of Comprehensive Diagnosis and Treatment of Oocyte Maturation Arrest, Chinese Academy of Medical Sciences, Beijing, China
| | - Rong Li
- Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
- National Clinical Research Center for Obstetrics and Gynecology, Beijing, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproduction, Beijing, China
- Research Units of Comprehensive Diagnosis and Treatment of Oocyte Maturation Arrest, Chinese Academy of Medical Sciences, Beijing, China
| | - Jie Yan
- Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
- National Clinical Research Center for Obstetrics and Gynecology, Beijing, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproduction, Beijing, China
- Research Units of Comprehensive Diagnosis and Treatment of Oocyte Maturation Arrest, Chinese Academy of Medical Sciences, Beijing, China
- *Correspondence: Jie Yan,
| | - Jie Qiao
- Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
- National Clinical Research Center for Obstetrics and Gynecology, Beijing, China
- Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproduction, Beijing, China
- Research Units of Comprehensive Diagnosis and Treatment of Oocyte Maturation Arrest, Chinese Academy of Medical Sciences, Beijing, China
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Alcicek FC, Mohaissen T, Bulat K, Dybas J, Szczesny-Malysiak E, Kaczmarska M, Franczyk-Zarow M, Kostogrys R, Marzec KM. Sex-Specific Differences of Adenosine Triphosphate Levels in Red Blood Cells Isolated From ApoE/LDLR Double-Deficient Mice. Front Physiol 2022; 13:839323. [PMID: 35250640 PMCID: PMC8895041 DOI: 10.3389/fphys.2022.839323] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Accepted: 01/27/2022] [Indexed: 12/16/2022] Open
Abstract
In this study for the first time, we investigated the correlation between sex-specific differences in adenosine triphosphate (ATP) levels in red blood cells (RBCs) and their mechanical, biochemical, and morphological alterations during the progression of atherosclerosis in ApoE/LDLR double-deficient (ApoE/LDLR−/−) mice. Our results indicate that both sex and age affect alterations in RBCs of both ApoE/LDLR−/− and C57BL/6J mice. When compared with male RBCs, female RBCs were characterized by lower basal ATP and mean corpuscular hemoglobin concentration (MCHC), higher hemoglobin concentration (HGB), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), deformability, and phosphatidylserine (PS) exposure levels, regardless of age in both, ApoE/LDLR−/− and C57BL/6J mice. ApoE/LDLR−/− mice compared with age-matched controls showed lower basal ATP levels regardless of age and sex. Intracellular ATP level of RBCs was decreased solely in senescent female C57BL/6J mice, while it was elevated in males. Basal extracellular ATP levels were 400 times lower than corresponding intracellular level. In conclusion, basal ATP levels, RBC morphology, deformability, PS exposure levels alterations are sex-dependent in mice. Changes in basal ATP levels were correlated with PS exposure and trends of changes in MCV. Trends of changes of the most RBC parameters were similar in both sexes of ApoE/LDLR−/− mice compared with age-matched controls; however, their kinetics and levels vary greatly between different stages of disease progression.
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Affiliation(s)
- Fatih Celal Alcicek
- Jagiellonian Centre for Experimental Therapeutics, Jagiellonian University, Krakow, Poland
| | - Tasnim Mohaissen
- Jagiellonian Centre for Experimental Therapeutics, Jagiellonian University, Krakow, Poland
- Chair and Faculty of Pharmacy, Jagiellonian University Medical College, Krakow, Poland
| | - Katarzyna Bulat
- Jagiellonian Centre for Experimental Therapeutics, Jagiellonian University, Krakow, Poland
- Łukasiewicz Research Network - Krakow Institute of Technology, Krakow, Poland
| | - Jakub Dybas
- Jagiellonian Centre for Experimental Therapeutics, Jagiellonian University, Krakow, Poland
| | - Ewa Szczesny-Malysiak
- Jagiellonian Centre for Experimental Therapeutics, Jagiellonian University, Krakow, Poland
| | - Magdalena Kaczmarska
- Jagiellonian Centre for Experimental Therapeutics, Jagiellonian University, Krakow, Poland
| | - Magdalena Franczyk-Zarow
- Department of Human Nutrition and Dietetics, Faculty of Food Technology, University of Agriculture, Krakow, Poland
| | - Renata Kostogrys
- Department of Human Nutrition and Dietetics, Faculty of Food Technology, University of Agriculture, Krakow, Poland
| | - Katarzyna M. Marzec
- Jagiellonian Centre for Experimental Therapeutics, Jagiellonian University, Krakow, Poland
- Łukasiewicz Research Network - Krakow Institute of Technology, Krakow, Poland
- *Correspondence: Katarzyna M. Marzec,
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9
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Lu Z, Huang L, Li Y, Xu Y, Zhang R, Zhou Q, Sun Q, Lu Y, Chen J, Shen Y, Li J, Zhao B. Fine-Tuning of Cholesterol Homeostasis Controls Erythroid Differentiation. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2102669. [PMID: 34739188 PMCID: PMC8805577 DOI: 10.1002/advs.202102669] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 10/01/2021] [Indexed: 05/12/2023]
Abstract
Lipid metabolism is essential for stemness maintenance, self-renewal, and differentiation of stem cells, however, the regulatory function of cholesterol metabolism in erythroid differentiation is poorly studied. In the present study, a critical role for cholesterol homeostasis in terminal erythropoiesis is uncovered. The master transcriptional factor GATA1 binds to Sterol-regulatory element binding protein 2 (SREBP2) to downregulate cholesterol biosynthesis, leading to a gradual reduction in intracellular cholesterol levels. It is further shown that reduced cholesterol functions to block erythroid proliferation via the cholesterol/mTORC1/ribosome biogenesis axis, which coordinates cell cycle exit in the late stages of erythroid differentiation. The interaction of GATA1 and SREBP2 also provides a feedback loop for regulating globin expression through the transcriptional control of NFE2 by SREBP2. Importantly, it is shown that disrupting intracellular cholesterol hemostasis resulted in defect of terminal erythroid differentiation in vivo. These findings demonstrate that fine-tuning of cholesterol homeostasis emerges as a key mechanism for regulating erythropoiesis.
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Affiliation(s)
- Zhiyuan Lu
- Key Laboratory of Chemical Biology (Ministry of Education)School of Pharmaceutical SciencesCheeloo College of MedicineShandong UniversityJinanShandong250012China
| | - Lixia Huang
- Department of Biochemistry and Molecular BiologySchool of Basic Medical SciencesCheeloo College of MedicineShandong UniversityJinanShandong250012China
| | - Yanxia Li
- Key Laboratory of Chemical Biology (Ministry of Education)School of Pharmaceutical SciencesCheeloo College of MedicineShandong UniversityJinanShandong250012China
| | - Yan Xu
- Key Laboratory of Chemical Biology (Ministry of Education)School of Pharmaceutical SciencesCheeloo College of MedicineShandong UniversityJinanShandong250012China
| | - Ruihao Zhang
- Department of Biochemistry and Molecular BiologySchool of Basic Medical SciencesCheeloo College of MedicineShandong UniversityJinanShandong250012China
| | - Qian Zhou
- Key Laboratory of Chemical Biology (Ministry of Education)School of Pharmaceutical SciencesCheeloo College of MedicineShandong UniversityJinanShandong250012China
| | - Qi Sun
- Department of Biochemistry and Molecular BiologySchool of Basic Medical SciencesCheeloo College of MedicineShandong UniversityJinanShandong250012China
| | - Yi Lu
- Department of Biochemistry and Molecular BiologySchool of Basic Medical SciencesCheeloo College of MedicineShandong UniversityJinanShandong250012China
| | - Junjie Chen
- Analysis and Measurement CenterSchool of Pharmaceutical SciencesXiamen UniversityXiamenFujian361001China
| | - Yuemao Shen
- Key Laboratory of Chemical Biology (Ministry of Education)School of Pharmaceutical SciencesCheeloo College of MedicineShandong UniversityJinanShandong250012China
| | - Jian Li
- Department of Biochemistry and Molecular BiologySchool of Basic Medical SciencesCheeloo College of MedicineShandong UniversityJinanShandong250012China
| | - Baobing Zhao
- Key Laboratory of Chemical Biology (Ministry of Education)School of Pharmaceutical SciencesCheeloo College of MedicineShandong UniversityJinanShandong250012China
- Department of PharmacologySchool of Pharmaceutical SciencesCheeloo College of MedicineShandong UniversityJinanShandong250012China
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10
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Abstract
Plasma HDL-cholesterol concentrations correlate negatively with the risk of atherosclerotic cardiovascular disease (ASCVD). According to a widely cited model, HDL elicits its atheroprotective effect through its role in reverse cholesterol transport, which comprises the efflux of cholesterol from macrophages to early forms of HDL, followed by the conversion of free cholesterol (FCh) contained in HDL into cholesteryl esters, which are hepatically extracted from the plasma by HDL receptors and transferred to the bile for intestinal excretion. Given that increasing plasma HDL-cholesterol levels by genetic approaches does not reduce the risk of ASCVD, the focus of research has shifted to HDL function, especially in the context of macrophage cholesterol efflux. In support of the reverse cholesterol transport model, several large studies have revealed an inverse correlation between macrophage cholesterol efflux to plasma HDL and ASCVD. However, other studies have cast doubt on the underlying reverse cholesterol transport mechanism: in mice and humans, the FCh contained in HDL is rapidly cleared from the plasma (within minutes), independently of esterification and HDL holoparticle uptake by the liver. Moreover, the reversibility of FCh transfer between macrophages and HDL has implicated the reverse process - that is, the transfer of FCh from HDL to macrophages - in the aetiology of increased ASCVD under conditions of very high plasma HDL-FCh concentrations.
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11
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Liu J, Gillard BK, Yelamanchili D, Gotto AM, Rosales C, Pownall HJ. High Free Cholesterol Bioavailability Drives the Tissue Pathologies in Scarb1 -/- Mice. Arterioscler Thromb Vasc Biol 2021; 41:e453-e467. [PMID: 34380332 PMCID: PMC8458258 DOI: 10.1161/atvbaha.121.316535] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Objective: Overall and atherosclerosis-associated mortality is elevated in humans with very high HDL (high-density lipoprotein) cholesterol concentrations. Mice with a deficiency of the HDL receptor, Scarb1 (scavenger receptor class B type 1), are a robust model of this phenotype and exhibit several additional pathologies. We hypothesized that the previously reported high plasma concentration of free cholesterol (FC)-rich HDL in Scarb1-/- mice produces a state of high HDL-FC bioavailability that increases whole-body FC and dysfunction in multiple tissue sites. Approach and Results: The higher mol% FC in Scarb1-/- versus WT (wild type) HDL (41.1 versus 16.0 mol%) affords greater FC bioavailability for transfer to multiple sites. Plasma clearance of autologous HDL-FC mass was faster in WT versus Scarb1-/- mice. FC influx from Scarb1-/- HDL to LDL (low-density lipoprotein) and J774 macrophages was greater ([almost equal to]4x) than that from WT HDL, whereas FC efflux capacity was similar. The higher mol% FC of ovaries, erythrocytes, heart, and macrophages of Scarb1-/- versus WT mice is associated with previously reported female infertility, impaired cell maturation, cardiac dysfunction, and atherosclerosis. The FC contents of other tissues were similar in the two genotypes, and these tissues were not associated with any overt pathology. In addition to the differences between WT versus Scarb1-/- mice, there were many sex-dependent differences in tissue-lipid composition and plasma FC clearance rates. Conclusions: Higher HDL-FC bioavailability among Scarb1-/- versus WT mice drives increased FC content of multiple cell sites and is a potential biomarker that is mechanistically linked to multiple pathologies.
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Affiliation(s)
- Jing Liu
- Department of Cardiovascular Medicine, Xiangya Hospital, Central South University, Changsha 410008, China
- Center for Bioenergetics, Houston Methodist Research Institute, 6670 Bertner Avenue, Houston TX 77030, USA
| | - Baiba K. Gillard
- Center for Bioenergetics, Houston Methodist Research Institute, 6670 Bertner Avenue, Houston TX 77030, USA
- Department of Medicine, Weill Cornell Medicine, 1300 York Ave, New York, NY, 10065, USA
| | - Dedipya Yelamanchili
- Center for Bioenergetics, Houston Methodist Research Institute, 6670 Bertner Avenue, Houston TX 77030, USA
| | - Antonio M. Gotto
- Center for Bioenergetics, Houston Methodist Research Institute, 6670 Bertner Avenue, Houston TX 77030, USA
- Department of Medicine, Weill Cornell Medicine, 1300 York Ave, New York, NY, 10065, USA
| | - Corina Rosales
- Center for Bioenergetics, Houston Methodist Research Institute, 6670 Bertner Avenue, Houston TX 77030, USA
- Department of Medicine, Weill Cornell Medicine, 1300 York Ave, New York, NY, 10065, USA
| | - Henry J. Pownall
- Center for Bioenergetics, Houston Methodist Research Institute, 6670 Bertner Avenue, Houston TX 77030, USA
- Department of Medicine, Weill Cornell Medicine, 1300 York Ave, New York, NY, 10065, USA
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12
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Changes of Hematological and Hemorheological Parameters in Rabbits with Hypercholesterolemia. Metabolites 2021; 11:metabo11040249. [PMID: 33920738 PMCID: PMC8072928 DOI: 10.3390/metabo11040249] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Revised: 04/15/2021] [Accepted: 04/16/2021] [Indexed: 12/19/2022] Open
Abstract
Hypercholesterolemia plays an important role in the development of atherosclerosis, leading to endothelial dysfunction, ischemic events, and increased mortality. Numerous studies suggest the pivotal role of rheological factors in the pathology of atherosclerosis. To get a more detailed hematological and hemorheological profile in hypercholesterolemia, we carried out an experiment on rabbits. Animals were divided into two groups: the control group (Control) was kept on normal rabbit chow, the high-cholesterol diet group (HC) was fed with special increased cholesterol-containing food. Hematological parameters (Sysmex K-4500 automate), whole blood and plasma viscosity (Hevimet-40 capillary viscometer), red blood cell (RBC) aggregation (Myrenne MA-1 aggregometer), deformability and mechanical stability (LoRRca MaxSis Osmoscan ektacytometer) were tested. The white blood cell and platelet count, mean corpuscular volume, and mean corpuscular hemoglobin were significantly higher in the HC group, while the RBC count, hemoglobin, and hematocrit values were lower than the Control data. Viscosity values corrected to 40% hematocrit were higher in the HC group. The RBC aggregation significantly increased in the HC vs. the Control. The HC group showed significantly worse results both in RBCs' deformability and membrane stability. In conclusion, the atherogenic diet worsens the hematological and macro- and micro-rheological parameters, affecting blood flow properties and microcirculation.
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13
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Tao H, Yancey PG, Blakemore JL, Zhang Y, Ding L, Jerome WG, Brown JD, Vickers KC, Linton MF. Macrophage SR-BI modulates autophagy via VPS34 complex and PPARα transcription of Tfeb in atherosclerosis. J Clin Invest 2021; 131:94229. [PMID: 33661763 PMCID: PMC8011903 DOI: 10.1172/jci94229] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 02/17/2021] [Indexed: 12/11/2022] Open
Abstract
Autophagy modulates lipid turnover, cell survival, inflammation, and atherogenesis. Scavenger receptor class B type I (SR-BI) plays a crucial role in lysosome function. Here, we demonstrate that SR-BI regulates autophagy in atherosclerosis. SR-BI deletion attenuated lipid-induced expression of autophagy mediators in macrophages and atherosclerotic aortas. Consequently, SR-BI deletion resulted in 1.8- and 2.5-fold increases in foam cell formation and apoptosis, respectively, and increased oxidized LDL-induced inflammatory cytokine expression. Pharmacological activation of autophagy failed to reduce lipid content or apoptosis in Sr-b1-/- macrophages. SR-BI deletion reduced both basal and inducible levels of transcription factor EB (TFEB), a master regulator of autophagy, causing decreased expression of autophagy genes encoding VPS34 and Beclin-1. Notably, SR-BI regulated Tfeb expression by enhancing PPARα activation. Moreover, intracellular macrophage SR-BI localized to autophagosomes, where it formed cholesterol domains resulting in enhanced association of Barkor and recruitment of the VPS34-Beclin-1 complex. Thus, SR-BI deficiency led to lower VPS34 activity in macrophages and in atherosclerotic aortic tissues. Overexpression of Tfeb or Vps34 rescued the defective autophagy in Sr-b1-/- macrophages. Taken together, our results show that macrophage SR-BI regulates autophagy via Tfeb expression and recruitment of the VPS34-Beclin-1 complex, thus identifying previously unrecognized roles for SR-BI and potentially novel targets for the treatment of atherosclerosis.
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Affiliation(s)
- Huan Tao
- Department of Medicine, Atherosclerosis Research Unit, Division of Cardiovascular Medicine
| | - Patricia G. Yancey
- Department of Medicine, Atherosclerosis Research Unit, Division of Cardiovascular Medicine
| | - John L. Blakemore
- Department of Medicine, Atherosclerosis Research Unit, Division of Cardiovascular Medicine
| | - Youmin Zhang
- Department of Medicine, Atherosclerosis Research Unit, Division of Cardiovascular Medicine
| | - Lei Ding
- Department of Medicine, Atherosclerosis Research Unit, Division of Cardiovascular Medicine
| | - W. Gray Jerome
- Department of Pathology, Microbiology and Immunology, and
| | - Jonathan D. Brown
- Department of Medicine, Atherosclerosis Research Unit, Division of Cardiovascular Medicine
| | - Kasey C. Vickers
- Department of Medicine, Atherosclerosis Research Unit, Division of Cardiovascular Medicine
| | - MacRae F. Linton
- Department of Medicine, Atherosclerosis Research Unit, Division of Cardiovascular Medicine
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
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14
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Dybas J, Bulat K, Blat A, Mohaissen T, Wajda A, Mardyla M, Kaczmarska M, Franczyk-Zarow M, Malek K, Chlopicki S, Marzec KM. Age-related and atherosclerosis-related erythropathy in ApoE/LDLR -/- mice. Biochim Biophys Acta Mol Basis Dis 2020; 1866:165972. [PMID: 32949768 DOI: 10.1016/j.bbadis.2020.165972] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 08/30/2020] [Accepted: 09/14/2020] [Indexed: 10/24/2022]
Abstract
In this work we applied a multimodal approach to define the age- and atherosclerosis-related biochemical and functional alterations in red blood cells (RBCs) in ApoE/LDLR-/- mice. Our results revealed that age-related changes in RBCs, such as decreases in RBC deformability and mean height, were more pronounced in ApoE/LDLR-/- mice than in age-matched control mice (C57BL/6J). The decreases in phospholipid content and level of lipid unsaturation were accompanied by an increase in cholesterol esters and esterified lipids in RBC membranes in aged C57BL/6J mice. The age-related decrease in the phospholipid content was more pronounced in ApoE/LDLR-/- mice. In contrast, the increase in the total lipid content in RBC membranes occurred only in ApoE/LDLR-/- mice with advanced atherosclerosis. The age-related alterations also included a decrease in the ratio of turns to α-helices in the secondary structure of hemoglobin (Hb) inside intact RBCs. On the other hand, an increase in the ratio of unordered conformations to α-helices of Hb was observed only in ApoE/LDLR-/- mice and occurred already at the age of 5-weeks. This was related to hypercholesterolemia and resulted in an increased oxygen-carrying capacity. In conclusion, progressive mechanical and functional alterations of RBCs in aged ApoE/LDLR-/- mice were more pronounced than in age-matched C57BL/6J mice. Although, several biochemical changes in RBCs in aged ApoE/LDLR-/- mice recapitulated age-dependent changes observed in control mice, some biochemical features of RBC membranes attributed to hypercholesterolemia were distinct and could contribute to the accelerated deterioration of RBC function in ApoE/LDLR-/- mice.
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Affiliation(s)
- Jakub Dybas
- Jagiellonian Center for Experimental Therapeutics, Jagiellonian University, 14 Bobrzyńskiego St., 30-348 Krakow, Poland
| | - Katarzyna Bulat
- Jagiellonian Center for Experimental Therapeutics, Jagiellonian University, 14 Bobrzyńskiego St., 30-348 Krakow, Poland
| | - Aneta Blat
- Jagiellonian Center for Experimental Therapeutics, Jagiellonian University, 14 Bobrzyńskiego St., 30-348 Krakow, Poland; Faculty of Chemistry, Jagiellonian University, 2 Gronostajowa Str., 30-387 Krakow, Poland
| | - Tasnim Mohaissen
- Jagiellonian Center for Experimental Therapeutics, Jagiellonian University, 14 Bobrzyńskiego St., 30-348 Krakow, Poland; Faculty of Pharmacy, Jagiellonian University Medical College, 9 Medyczna Str., 30-688 Krakow, Poland
| | - Aleksandra Wajda
- Jagiellonian Center for Experimental Therapeutics, Jagiellonian University, 14 Bobrzyńskiego St., 30-348 Krakow, Poland; Faculty of Materials Science and Ceramics, AGH University of Science and Technology, Mickiewicza 30, 30-059 Krakow, Poland
| | - Mateusz Mardyla
- Jagiellonian Center for Experimental Therapeutics, Jagiellonian University, 14 Bobrzyńskiego St., 30-348 Krakow, Poland; Jagiellonian University, University School of Physical Education in Krakow, 78 Jana Pawła II St., 31-571 Krakow, Poland
| | - Magdalena Kaczmarska
- Jagiellonian Center for Experimental Therapeutics, Jagiellonian University, 14 Bobrzyńskiego St., 30-348 Krakow, Poland
| | - Magdalena Franczyk-Zarow
- Department of Human Nutrition and Dietetics, Faculty of Food Technology, University of Agriculture, 122 Balicka St., 30-149 Krakow, Poland
| | - Kamilla Malek
- Faculty of Chemistry, Jagiellonian University, 2 Gronostajowa Str., 30-387 Krakow, Poland
| | - Stefan Chlopicki
- Jagiellonian Center for Experimental Therapeutics, Jagiellonian University, 14 Bobrzyńskiego St., 30-348 Krakow, Poland; Department of Experimental Pharmacology, Jagiellonian University Medical College, 16 Grzegorzecka St., 31-531 Krakow, Poland
| | - Katarzyna M Marzec
- Jagiellonian Center for Experimental Therapeutics, Jagiellonian University, 14 Bobrzyńskiego St., 30-348 Krakow, Poland.
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15
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Kiatpakdee B, Sato K, Otsuka Y, Arashiki N, Chen Y, Tsumita T, Otsu W, Yamamoto A, Kawata R, Yamazaki J, Sugimoto Y, Takada K, Mohandas N, Inaba M. Cholesterol-binding protein TSPO2 coordinates maturation and proliferation of terminally differentiating erythroblasts. J Biol Chem 2020; 295:8048-8063. [PMID: 32358067 PMCID: PMC7278357 DOI: 10.1074/jbc.ra119.011679] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 04/20/2020] [Indexed: 02/02/2023] Open
Abstract
TSPO2 (translocator protein 2) is a transmembrane protein specifically expressed in late erythroblasts and has been postulated to mediate intracellular redistribution of cholesterol. We identified TSPO2 as the causative gene for the HK (high-K+) trait with immature red cell phenotypes in dogs and investigated the effects of the TSPO2 defects on erythropoiesis in HK dogs with the TSPO2 mutation and Tspo2 knockout (Tspo2−/−) mouse models. Bone marrow–derived erythroblasts from HK dogs showed increased binucleated and apoptotic cells at various stages of maturation and shed large nuclei with incomplete condensation when cultured in the presence of erythropoietin, indicating impaired maturation and cytokinesis. The canine TSPO2 induces cholesterol accumulation in the endoplasmic reticulum and could thereby regulate cholesterol availability by changing intracellular cholesterol distribution in erythroblasts. Tspo2−/− mice consistently showed impaired cytokinesis with increased binucleated erythroblasts, resulting in compensated anemia, and their red cell membranes had increased Na,K-ATPase, resembling the HK phenotype in dogs. Tspo2-deficient mouse embryonic stem cell–derived erythroid progenitor (MEDEP) cells exhibited similar morphological defects associated with a cell-cycle arrest at the G2/M phase, resulting in decreased cell proliferation and had a depletion in intracellular unesterified and esterified cholesterol. When the terminal maturation was induced, Tspo2−/− MEDEP cells showed delays in hemoglobinization; maturation-associated phenotypic changes in CD44, CD71, and TER119 expression; and cell-cycle progression. Taken together, these findings imply that TSPO2 is essential for coordination of maturation and proliferation of erythroblasts during normal erythropoiesis.
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Affiliation(s)
- Benjaporn Kiatpakdee
- Laboratory of Molecular Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Kota Sato
- Laboratory of Molecular Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Yayoi Otsuka
- Laboratory of Molecular Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Nobuto Arashiki
- Laboratory of Molecular Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Yuqi Chen
- Laboratory of Molecular Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Takuya Tsumita
- Laboratory of Molecular Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Wataru Otsu
- Laboratory of Molecular Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Akito Yamamoto
- Laboratory of Molecular Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Reo Kawata
- Laboratory of Molecular Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Jumpei Yamazaki
- Laboratory of Molecular Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | | | - Kensuke Takada
- Laboratory of Molecular Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Narla Mohandas
- Red Cell Physiology Laboratory, New York Blood Center, New York, New York, USA
| | - Mutsumi Inaba
- Laboratory of Molecular Medicine, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
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16
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Wang D, Huang J, Gui T, Yang Y, Feng T, Tzvetkov NT, Xu T, Gai Z, Zhou Y, Zhang J, Atanasov AG. SR-BI as a target of natural products and its significance in cancer. Semin Cancer Biol 2020; 80:18-38. [PMID: 31935456 DOI: 10.1016/j.semcancer.2019.12.025] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 11/25/2019] [Accepted: 12/30/2019] [Indexed: 02/07/2023]
Abstract
Scavenger receptor class B type I (SR-BI) protein is an integral membrane glycoprotein. SR-BI is emerging as a multifunctional protein, which regulates autophagy, efferocytosis, cell survival and inflammation. It is well known that SR-BI plays a critical role in lipoprotein metabolism by mediating cholesteryl esters selective uptake and the bi-directional flux of free cholesterol. Recently, SR-BI has also been identified as a potential marker for cancer diagnosis, prognosis, or even a treatment target. Natural products are a promising source for the discovery of new drug leads. Multiple natural products were identified to regulate SR-BI protein expression. There are still a number of challenges in modulating SR-BI expression in cancer and in using natural products for modulation of such protein expression. In this review, our purpose is to discuss the relationship between SR-BI protein and cancer, and the molecular mechanisms regulating SR-BI expression, as well as to provide an overview of natural products that regulate SR-BI expression.
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Affiliation(s)
- Dongdong Wang
- The Second Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, Fei Shan Jie 32, 550003, Guiyang, China
| | - Jiansheng Huang
- Department of Medicine, Vanderbilt University Medical Center, 318 Preston Research Building, 2200 Pierce Avenue, Nashville, Tennessee, 37232, USA
| | - Ting Gui
- Key Laboratory of Traditional Chinese Medicine for Classical Theory, Ministry of Education, Shandong University of Traditional Chinese Medicine, Jinan, 250355, China
| | - Yaxin Yang
- The Second Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, Fei Shan Jie 32, 550003, Guiyang, China
| | - Tingting Feng
- College of Pharmacy, Guizhou University of Traditional Chinese Medicine, Huaxi university town, 550025, Guiyang, China
| | - Nikolay T Tzvetkov
- Department of Biochemical Pharmacology and Drug Design, Institute of Molecular Biology "Roumen Tsanev", Bulgarian Academy of Sciences, 21 Acad. G. Bonchev Str., 1113 Sofia, Bulgaria
| | - Tao Xu
- The Second Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, Fei Shan Jie 32, 550003, Guiyang, China
| | - Zhibo Gai
- Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Ying Zhou
- College of Pharmacy, Guizhou University of Traditional Chinese Medicine, Huaxi university town, 550025, Guiyang, China.
| | - Jingjie Zhang
- The Second Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, Fei Shan Jie 32, 550003, Guiyang, China.
| | - Atanas G Atanasov
- Department of Molecular Biology, Institute of Genetics and Animal Breeding of the Polish Academy of Sciences, 05-552, Jastrzębiec, Poland; Department of Pharmacognosy, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria; Institute of Neurobiology, Bulgarian Academy of Sciences, 23 Acad. G. Bonchev Str., 1113 Sofia, Bulgaria; Ludwig Boltzmann Institute for Digital Health and Patient Safety, Medical University of Vienna, Spitalgasse 23, 1090, Vienna, Austria.
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17
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Shen WJ, Asthana S, Kraemer FB, Azhar S. Scavenger receptor B type 1: expression, molecular regulation, and cholesterol transport function. J Lipid Res 2018; 59:1114-1131. [PMID: 29720388 DOI: 10.1194/jlr.r083121] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 04/26/2018] [Indexed: 12/16/2022] Open
Abstract
Cholesterol is required for maintenance of plasma membrane fluidity and integrity and for many cellular functions. Cellular cholesterol can be obtained from lipoproteins in a selective pathway of HDL-cholesteryl ester (CE) uptake without parallel apolipoprotein uptake. Scavenger receptor B type 1 (SR-B1) is a cell surface HDL receptor that mediates HDL-CE uptake. It is most abundantly expressed in liver, where it provides cholesterol for bile acid synthesis, and in steroidogenic tissues, where it delivers cholesterol needed for storage or steroidogenesis in rodents. SR-B1 transcription is regulated by trophic hormones in the adrenal gland, ovary, and testis; in the liver and elsewhere, SR-B1 is subject to posttranscriptional and posttranslational regulation. SR-B1 operates in several metabolic processes and contributes to pathogenesis of atherosclerosis, inflammation, hepatitis C virus infection, and other conditions. Here, we summarize characteristics of the selective uptake pathway and involvement of microvillar channels as facilitators of selective HDL-CE uptake. We also present the potential mechanisms of SR-B1-mediated selective cholesterol transport; the transcriptional, posttranscriptional, and posttranslational regulation of SR-B1; and the impact of gene variants on expression and function of human SR-B1. A better understanding of this unique pathway and SR-B1's role may yield improved therapies for a wide variety of conditions.
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Affiliation(s)
- Wen-Jun Shen
- Geriatric Research, Education, and Clinical Research Center (GRECC), Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304 and Division of Endocrinology, Gerontology, and Metabolism, Stanford University School of Medicine, Stanford, CA 94305
| | - Shailendra Asthana
- Drug Discovery Research Center (DDRC), Translational Health Science and Technology Institute (THSTI), NCR Biotech Science Cluster, Faridabad 121001, Haryana, India
| | - Fredric B Kraemer
- Geriatric Research, Education, and Clinical Research Center (GRECC), Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304 and Division of Endocrinology, Gerontology, and Metabolism, Stanford University School of Medicine, Stanford, CA 94305
| | - Salman Azhar
- Geriatric Research, Education, and Clinical Research Center (GRECC), Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304 and Division of Endocrinology, Gerontology, and Metabolism, Stanford University School of Medicine, Stanford, CA 94305
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18
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Gillard BK, Rosales C, Xu B, Gotto AM, Pownall HJ. Rethinking reverse cholesterol transport and dysfunctional high-density lipoproteins. J Clin Lipidol 2018; 12:849-856. [PMID: 29731282 DOI: 10.1016/j.jacl.2018.04.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 03/26/2018] [Accepted: 04/03/2018] [Indexed: 12/31/2022]
Abstract
Human plasma high-density lipoprotein cholesterol concentrations are a negative risk factor for atherosclerosis-linked cardiovascular disease. Pharmacological attempts to reduce atherosclerotic cardiovascular disease by increasing plasma high-density lipoprotein cholesterol have been disappointing so that recent research has shifted from HDL quantity to HDL quality, that is, functional vs dysfunctional HDL. HDL has varying degrees of dysfunction reflected in impaired reverse cholesterol transport (RCT). In the context of atheroprotection, RCT occurs by 2 mechanisms: one is the well-known trans-hepatic pathway comprising macrophage free cholesterol (FC) efflux, which produces early forms of FC-rich nascent HDL (nHDL). Lecithin:cholesterol acyltransferase converts HDL-FC to HDL-cholesteryl ester while converting nHDL from a disc to a mature spherical HDL, which transfers its cholesteryl ester to the hepatic HDL receptor, scavenger receptor B1 for uptake, conversion to bile salts, or transfer to the intestine for excretion. Although widely cited, current evidence suggests that this is a minor pathway and that most HDL-FC and nHDL-FC rapidly transfer directly to the liver independent of lecithin:cholesterol acyltransferase activity. A small fraction of plasma HDL-FC enters the trans-intestinal efflux pathway comprising direct FC transfer to the intestine. SR-B1-/- mice, which have impaired trans-hepatic FC transport, are characterized by high plasma levels of a dysfunctional FC-rich HDL that increases plasma FC bioavailability in a way that produces whole-body hypercholesterolemia and multiple pathologies. The design of future therapeutic strategies to improve RCT will have to be formulated in the context of these dual RCT mechanisms and the role of FC bioavailability.
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Affiliation(s)
- Baiba K Gillard
- Center for Bioenergetics, Houston Methodist Research Institute, Houston, TX, USA; Weill Cornell Medicine, New York, NY, USA
| | - Corina Rosales
- Center for Bioenergetics, Houston Methodist Research Institute, Houston, TX, USA; Weill Cornell Medicine, New York, NY, USA
| | - Bingqing Xu
- Department of Cardiovascular Medicine, Xiangya Hospital, Central South University, Changsha, China
| | - Antonio M Gotto
- Center for Bioenergetics, Houston Methodist Research Institute, Houston, TX, USA; Weill Cornell Medicine, New York, NY, USA
| | - Henry J Pownall
- Center for Bioenergetics, Houston Methodist Research Institute, Houston, TX, USA; Weill Cornell Medicine, New York, NY, USA.
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19
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Abstract
In this issue of Blood, Mankelow et al link phosphatidylserine (PS) exposure in sickle erythrocytes to a physiological event in reticulocyte maturation. This discovery has implications for efforts to prevent thrombosis in sickle cell disease (SCD).
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20
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Thacker SG, Rousset X, Esmail S, Zarzour A, Jin X, Collins HL, Sampson M, Stonik J, Demosky S, Malide DA, Freeman L, Vaisman BL, Kruth HS, Adelman SJ, Remaley AT. Increased plasma cholesterol esterification by LCAT reduces diet-induced atherosclerosis in SR-BI knockout mice. J Lipid Res 2015; 56:1282-95. [PMID: 25964513 PMCID: PMC4479333 DOI: 10.1194/jlr.m048629] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 04/27/2015] [Indexed: 12/15/2022] Open
Abstract
LCAT, a plasma enzyme that esterifies cholesterol, has been proposed to play an antiatherogenic role, but animal and epidemiologic studies have yielded conflicting results. To gain insight into LCAT and the role of free cholesterol (FC) in atherosclerosis, we examined the effect of LCAT over- and underexpression in diet-induced atherosclerosis in scavenger receptor class B member I-deficient [Scarab(-/-)] mice, which have a secondary defect in cholesterol esterification. Scarab(-/-)×LCAT-null [Lcat(-/-)] mice had a decrease in HDL-cholesterol and a high plasma ratio of FC/total cholesterol (TC) (0.88 ± 0.033) and a marked increase in VLDL-cholesterol (VLDL-C) on a high-fat diet. Scarab(-/-)×LCAT-transgenic (Tg) mice had lower levels of VLDL-C and a normal plasma FC/TC ratio (0.28 ± 0.005). Plasma from Scarab(-/-)×LCAT-Tg mice also showed an increase in cholesterol esterification during in vitro cholesterol efflux, but increased esterification did not appear to affect the overall rate of cholesterol efflux or hepatic uptake of cholesterol. Scarab(-/-)×LCAT-Tg mice also displayed a 51% decrease in aortic sinus atherosclerosis compared with Scarab(-/-) mice (P < 0.05). In summary, we demonstrate that increased cholesterol esterification by LCAT is atheroprotective, most likely through its ability to increase HDL levels and decrease pro-atherogenic apoB-containing lipoprotein particles.
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Affiliation(s)
- Seth G. Thacker
- Lipoprotein Metabolism Section, Cardiovascular-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Xavier Rousset
- Lipoprotein Metabolism Section, Cardiovascular-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Safiya Esmail
- Lipoprotein Metabolism Section, Cardiovascular-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Abdalrahman Zarzour
- Lipoprotein Metabolism Section, Cardiovascular-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Xueting Jin
- Experimental Atherosclerosis Section, Center for Molecular, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | | | - Maureen Sampson
- Department of Laboratory Medicine, Clinical Center, National Institutes of Health, Bethesda, MD 20892
| | - John Stonik
- Lipoprotein Metabolism Section, Cardiovascular-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Stephen Demosky
- Lipoprotein Metabolism Section, Cardiovascular-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Daniela A. Malide
- Light Microscopy Core, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Lita Freeman
- Lipoprotein Metabolism Section, Cardiovascular-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Boris L. Vaisman
- Lipoprotein Metabolism Section, Cardiovascular-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Howard S. Kruth
- Experimental Atherosclerosis Section, Center for Molecular, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | | | - Alan T. Remaley
- Lipoprotein Metabolism Section, Cardiovascular-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
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Excess cholesterol induces mouse egg activation and may cause female infertility. Proc Natl Acad Sci U S A 2014; 111:E4972-80. [PMID: 25368174 DOI: 10.1073/pnas.1418954111] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The HDL receptor scavenger receptor, class B type I (SR-BI) controls the structure and fate of plasma HDL. Female SR-BI KO mice are infertile, apparently because of their abnormal cholesterol-enriched HDL particles. We examined the growth and meiotic progression of SR-BI KO oocytes and found that they underwent normal germinal vesicle breakdown; however, SR-BI KO eggs, which had accumulated excess cholesterol in vivo, spontaneously activated, and they escaped metaphase II (MII) arrest and progressed to pronuclear, MIII, and anaphase/telophase III stages. Eggs from fertile WT mice were activated when loaded in vitro with excess cholesterol by a cholesterol/methyl-β-cyclodextrin complex, phenocopying SR-BI KO oocytes. In vitro cholesterol loading of eggs induced reduction in maturation promoting factor and MAPK activities, elevation of intracellular calcium, extrusion of a second polar body, and progression to meiotic stages beyond MII. These results suggest that the infertility of SR-BI KO females is caused, at least in part, by excess cholesterol in eggs inducing premature activation and that cholesterol can activate WT mouse eggs to escape from MII arrest. Analysis of SR-BI KO female infertility raises the possibility that abnormalities in cholesterol metabolism might underlie some cases of human female infertility of unknown etiology.
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22
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Guo L, Zheng Z, Ai J, Huang B, Li XA. Hepatic scavenger receptor BI protects against polymicrobial-induced sepsis through promoting LPS clearance in mice. J Biol Chem 2014; 289:14666-73. [PMID: 24719333 DOI: 10.1074/jbc.m113.537258] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Recent studies revealed that scavenger receptor BI (SR-BI or Scarb1) plays a critical protective role in sepsis. However, the mechanisms underlying this protection remain largely unknown. In this study, using Scarb1(I179N) mice, a mouse model specifically deficient in hepatic SR-BI, we report that hepatic SR-BI protects against cecal ligation and puncture (CLP)-induced sepsis as shown by 75% fatality in Scarb1(I179N) mice, but only 21% fatality in C57BL/6J control mice. The increase in fatality in Scarb1(I179N) mice was associated with an exacerbated inflammatory cytokine production. Further study demonstrated that hepatic SR-BI exerts its protection against sepsis through its role in promoting LPS clearance without affecting the inflammatory response in macrophages, the glucocorticoid production in adrenal glands, the leukocyte recruitment to peritoneum or the bacterial clearance in liver. Our findings reveal hepatic SR-BI as a critical protective factor in sepsis and point out that promoting hepatic SR-BI-mediated LPS clearance may provide a therapeutic approach for sepsis.
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Affiliation(s)
- Ling Guo
- From the Department of Pediatrics, Saha Cardiovascular Research Center
| | - Zhong Zheng
- From the Department of Pediatrics, Graduate Center for Nutritional Sciences, and
| | - Junting Ai
- From the Department of Pediatrics, Graduate Center for Nutritional Sciences, and
| | - Bin Huang
- Kentucky Cancer Registry, University of Kentucky College of Medicine, Lexington, Kentucky 40536
| | - Xiang-An Li
- From the Department of Pediatrics, Saha Cardiovascular Research Center, Kentucky Cancer Registry, University of Kentucky College of Medicine, Lexington, Kentucky 40536
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Abstract
PURPOSE OF REVIEW To summarize the recent findings about the roles of scavenger receptor class B type I (SR-BI) in immunity and discuss the underlying mechanisms by which SR-BI prevents immune dysfunctions. RECENT FINDINGS SR-BI is well known as a high-density lipoprotein (HDL) receptor playing key roles in HDL metabolism and in protection against atherosclerosis. Recent studies have indicated that SR-BI is also an essential modulator in immunity. SR-BI deficiency in mice causes immune dysfunctions, including increased atherosclerosis, elevated susceptibility to sepsis, impaired lymphocyte homeostasis, and autoimmune disorders. SR-BI exerts its protective roles through a variety of HDL-dependent and HDL-independent mechanisms. SR-BI is also involved in hepatitis C virus cell entry. A deficiency of SR-BI in humanized mice has been shown to decrease hepatitis C virus infectivity. SUMMARY SR-BI regulates immunity via multiple mechanisms and its deficiency causes numerous diseases. A comprehensive understanding of the roles of SR-BI in protection against immune dysfunctions may provide a therapeutic target for intervention against its associated diseases.
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Affiliation(s)
- Zhong Zheng
- Department of Pediatrics, University of Kentucky College of Medicine, Lexington, Kentucky, USA
- Graduate Center for Nutritional Sciences, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Junting Ai
- Department of Pediatrics, University of Kentucky College of Medicine, Lexington, Kentucky, USA
- Graduate Center for Nutritional Sciences, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Xiang-An Li
- Department of Pediatrics, University of Kentucky College of Medicine, Lexington, Kentucky, USA
- Graduate Center for Nutritional Sciences, University of Kentucky College of Medicine, Lexington, Kentucky, USA
- Saha Cardiovascular Research Center, University of Kentucky College of Medicine, Lexington, Kentucky, USA
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Fessler MB, Rose K, Zhang Y, Jaramillo R, Zeldin DC. Relationship between serum cholesterol and indices of erythrocytes and platelets in the US population. J Lipid Res 2013; 54:3177-88. [PMID: 23999863 DOI: 10.1194/jlr.p037614] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Whereas dyslipidemia has been associated with leukocytosis, the relationship between serum cholesterol and other hematopoietic lineages is poorly defined. Erythrocytes and platelets, anucleate cells relegated to nonspecific diffusional exchange of cholesterol with serum, have been proposed to have a distinct relationship to cholesterol from leukocytes. We examined the relationship between serum cholesterol and circulating erythrocyte/platelet indices in 4,469 adult participants of the National Health and Nutrition Examination Survey (NHANES) 2005-2006. In linear regression analyses, serum non-high density lipoprotein-cholesterol (non-HDL-C) was positively associated with mean erythrocyte number, hematocrit, hemoglobin concentration, platelet count, and platelet crit independently of age, gender, race/ethnicity, smoking, body mass index, serum folate, and C-reactive protein. The magnitude of the relationship was most marked for platelets, with lowest versus highest non-HDL-C quartile subjects having geometric mean platelet counts of 258,000/μl versus 281,000/μl, respectively (adjusted model, P < 0.001 for trend). These associations persisted in a sensitivity analysis excluding several conditions that affect erythrocyte/platelet and/or serum cholesterol levels, and were also noted in an independent analysis of 5,318 participants from NHANES 2007-2008. As non-HDL-C, erythrocytes, and platelets all impact cardiovascular disease risk, there is a need for advancing understanding of the underlying interactions that govern levels of these three blood components.
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Affiliation(s)
- Michael B Fessler
- Laboratory of Respiratory Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709
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Platelet hyperreactivity explains the bleeding abnormality and macrothrombocytopenia in a murine model of sitosterolemia. Blood 2013; 122:2732-42. [PMID: 23926302 DOI: 10.1182/blood-2013-06-510461] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Sitosterolemia is a rare, autosomal recessive disease caused by mutations in the adenosine triphosphate-binding cassette transporter genes ABCG5 or ABCG8 that result in accumulation of xenosterols in the body. Clinical manifestations include tendon xanthomas, premature coronary artery disease, hemolytic anemia, macrothrombocytopenia, and bleeding. Although the effect of sterol accumulation on the predisposition for atherosclerosis is evident, how xenosterol accumulation leads to defects in platelet physiology is unknown. Sitosterolemia induced in Abcg5- and Abcg8-deficient mice fed a high plant sterol diet resulted in accumulation of free sterols in platelet plasma membranes, leading to hyperactivatable platelets characterized by constitutive binding of fibrinogen to its αIIbβ3 integrin receptor, internalization of the αIIbβ3 complex, generation of platelet-derived microparticles, and changes in the quantity and subcellular localization of filamin. The latter was associated with macrothrombocytopenia, shedding of GPIbα, impaired platelet adhesion to von Willebrand factor, and inability to form stable thrombi. Plasma levels of soluble GPIbα were strongly correlated with plasma sitosterol levels in samples from human sitosterolemic patients, implicating a similar mechanism of sterol-induced platelet passivation in the human disease. Intercalation of plant sterols into the plasma membrane therefore results in dysregulation of multiple platelet activation pathways, leading to macrothrombocytopenia and bleeding.
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26
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Maturing reticulocytes internalize plasma membrane in glycophorin A-containing vesicles that fuse with autophagosomes before exocytosis. Blood 2012; 119:6296-306. [PMID: 22490681 DOI: 10.1182/blood-2011-09-376475] [Citation(s) in RCA: 138] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The erythrocyte is one of the best characterized human cells. However, studies of the process whereby human reticulocytes mature to erythrocytes have been hampered by the difficulty of obtaining sufficient numbers of cells for analysis. In the present study, we describe an in vitro culture system producing milliliter quantities of functional mature human adult reticulocytes from peripheral blood CD34(+) cells. We show that the final stage of reticulocyte maturation occurs by a previously undescribed mechanism in which large glycophorin A-containing vesicles forming at the cytosolic face of the plasma membrane are internalized and fuse with autophagosomes before expulsion of the autophagosomal contents by exocytosis. Early reticulocyte maturation is characterized by the selective elimination of unwanted plasma membrane proteins (CD71, CD98, and β1 integrin) through the endosome-exosome pathway. In contrast, late maturation is characterized by the generation of large glycophorin A-decorated vesicles of autophagic origin.
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27
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Abstract
PURPOSE OF REVIEW HDL cholesterol levels have been inversely correlated with thrombosis and HDL has been shown to mediate various antithrombotic effects. However, molecular mechanisms underlying the suppressing effect of HDL on platelet reactivity are not completely understood. The present review summarizes the recent advancements in understanding the role played by scavenger receptor class B type I (SR-BI) - an HDL receptor - in modulating platelet function and mediating platelet-HDL interactions. RECENT FINDINGS SR-BI is expressed on platelet surface and platelets from SR-BI knockout animals are characterized by increased free-to-total cholesterol ratio, abnormal morphology, increased reactivity to strong platelets agonists, enhanced adherence to immobilized fibrinogen, and a propensity to form arterial thrombi. Crossover incubation experiments and a bone marrow transplantation approach reveal increased wild-type platelet reactivity in plasma from SR-BI mice and normal or decreased SR-BI-deficient platelet reactivity in wild-type plasma. A similar functional platelet phenotype has been observed in human carriers of an SR-BI genetic variant. SR-BI ligands interfere with HDL binding to murine platelets and impede the agonist-induced platelet activation as effectively as native HDL. The inhibitory effects of native HDL, moderately oxidized HDL, and SR-BI ligands are abolished in SR-BI-deficient platelets but not in CD36-deficient platelets. SUMMARY SR-BI exerts an indirect influence on platelet reactivity via maintaining normal plasma cholesterol homeostasis. In addition, SR-BI is a functional receptor for native and moderately oxidized HDL on platelets that generates an inhibitory signal for platelet activation.
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Affiliation(s)
- Jerzy-Roch Nofer
- Center for Laboratory Medicine, University Hospital Münster, Münster, Germany.
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28
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Nieland TJ, Xu S, Penman M, Krieger M. Negatively cooperative binding of high-density lipoprotein to the HDL receptor SR-BI. Biochemistry 2011; 50:1818-30. [PMID: 21254782 PMCID: PMC3065119 DOI: 10.1021/bi101657j] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Scavenger receptor class B, type I (SR-BI), is a high-density lipoprotein (HDL) receptor, which also binds low-density lipoprotein (LDL), and mediates the cellular selective uptake of cholesteryl esters from lipoproteins. SR-BI also is a coreceptor for hepatitis C virus and a signaling receptor that regulates cell metabolism. Many investigators have reported that lipoproteins bind to SR-BI via a single class of independent (not interacting), high-affinity binding sites (one site model). We have reinvestigated the ligand concentration dependence of (125)I-HDL binding to SR-BI and SR-BI-mediated specific uptake of [(3)H]CE from [(3)H]CE-HDL using an expanded range of ligand concentrations (<1 μg of protein/mL, lower than previously reported). Scatchard and nonlinear least-squares model fitting analyses of the binding and uptake data were both inconsistent with a single class of independent binding sites binding univalent lipoprotein ligands. The data are best fit by models in which SR-BI has either two independent classes of binding sites or one class of sites exhibiting negative cooperativity due to either classic allostery or ensemble effects ("lattice model"). Similar results were observed for LDL. Application of the "infinite dilution" dissociation rate method established that the binding of (125)I-HDL to SR-BI at 4 °C exhibits negative cooperativity. The unexpected complexity of the interactions of lipoproteins with SR-BI should be taken into account when interpreting the results of experiments that explore the mechanism(s) by which SR-BI mediates ligand binding, lipid transport, and cell signaling.
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Affiliation(s)
- Thomas J.F. Nieland
- Department of Biology, Massachusetts Institute of Technology, Room 68-483, 77 Massachusetts Avenue, Cambridge, MA 02139
- Broad Institute of Harvard and MIT, 7 Cambridge Center, Cambridge, MA 02142
| | - Shangzhe Xu
- Department of Biology, Massachusetts Institute of Technology, Room 68-483, 77 Massachusetts Avenue, Cambridge, MA 02139
| | - Marsha Penman
- Department of Biology, Massachusetts Institute of Technology, Room 68-483, 77 Massachusetts Avenue, Cambridge, MA 02139
| | - Monty Krieger
- Department of Biology, Massachusetts Institute of Technology, Room 68-483, 77 Massachusetts Avenue, Cambridge, MA 02139
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29
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El Bouhassani M, Gilibert S, Moreau M, Saint-Charles F, Tréguier M, Poti F, Chapman MJ, Le Goff W, Lesnik P, Huby T. Cholesteryl ester transfer protein expression partially attenuates the adverse effects of SR-BI receptor deficiency on cholesterol metabolism and atherosclerosis. J Biol Chem 2011; 286:17227-38. [PMID: 21454568 DOI: 10.1074/jbc.m111.220483] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Scavenger receptor SR-BI significantly contributes to HDL cholesterol metabolism and atherogenesis in mice. However, the role of SR-BI may not be as pronounced in humans due to cholesteryl ester transfer protein (CETP) activity. To address the impact of CETP expression on the adverse effects associated with SR-BI deficiency, we cross-bred our SR-BI conditional knock-out mouse model with CETP transgenic mice. CETP almost completely restored the abnormal HDL-C distribution in SR-BI-deficient mice. However, it did not normalize the elevated plasma free to total cholesterol ratio characteristic of hepatic SR-BI deficiency. Red blood cell and platelet count abnormalities observed in mice liver deficient for SR-BI were partially restored by CETP, but the elevated erythrocyte cholesterol to phospholipid ratio remained unchanged. Complete deletion of SR-BI was associated with diminished adrenal cholesterol stores, whereas hepatic SR-BI deficiency resulted in a significant increase in adrenal gland cholesterol content. In both mouse models, CETP had no impact on adrenal cholesterol metabolism. In diet-induced atherosclerosis studies, hepatic SR-BI deficiency accelerated aortic lipid lesion formation in both CETP-expressing (4-fold) and non-CETP-expressing (8-fold) mice when compared with controls. Impaired macrophage to feces reverse cholesterol transport in mice deficient for SR-BI in liver, which was not corrected by CETP, most likely contributed by such an increase in atherosclerosis susceptibility. Finally, comparison of the atherosclerosis burden in SR-BI liver-deficient and fully deficient mice demonstrated that SR-BI exerted an atheroprotective activity in extra-hepatic tissues whether CETP was present or not. These findings support the contention that the SR-BI pathway contributes in unique ways to cholesterol metabolism and atherosclerosis susceptibility even in the presence of CETP.
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30
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Kocher O, Birrane G, Tsukamoto K, Fenske S, Yesilaltay A, Pal R, Daniels K, Ladias JAA, Krieger M. In vitro and in vivo analysis of the binding of the C terminus of the HDL receptor scavenger receptor class B, type I (SR-BI), to the PDZ1 domain of its adaptor protein PDZK1. J Biol Chem 2010; 285:34999-5010. [PMID: 20739281 DOI: 10.1074/jbc.m110.164418] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The PDZ1 domain of the four PDZ domain-containing protein PDZK1 has been reported to bind the C terminus of the HDL receptor scavenger receptor class B, type I (SR-BI), and to control hepatic SR-BI expression and function. We generated wild-type (WT) and mutant murine PDZ1 domains, the mutants bearing single amino acid substitutions in their carboxylate binding loop (Lys(14)-Xaa(4)-Asn(19)-Tyr-Gly-Phe-Phe-Leu(24)), and measured their binding affinity for a 7-residue peptide corresponding to the C terminus of SR-BI ((503)VLQEAKL(509)). The Y20A and G21Y substitutions abrogated all binding activity. Surprisingly, binding affinities (K(d)) of the K14A and F22A mutants were 3.2 and 4.0 μM, respectively, similar to 2.6 μM measured for the WT PDZ1. To understand these findings, we determined the high resolution structure of WT PDZ1 bound to a 5-residue sequence from the C-terminal SR-BI ((505)QEAKL(509)) using x-ray crystallography. In addition, we incorporated the K14A and Y20A substitutions into full-length PDZK1 liver-specific transgenes and expressed them in WT and PDZK1 knock-out mice. In WT mice, the transgenes did not alter endogenous hepatic SR-BI protein expression (intracellular distribution or amount) or lipoprotein metabolism (total plasma cholesterol, lipoprotein size distribution). In PDZK1 knock-out mice, as expected, the K14A mutant behaved like wild-type PDZK1 and completely corrected their hepatic SR-BI and plasma lipoprotein abnormalities. Unexpectedly, the 10-20-fold overexpressed Y20A mutant also substantially, but not completely, corrected these abnormalities. The results suggest that there may be an additional site(s) within PDZK1 that bind(s) SR-BI and mediate(s) productive SR-BI-PDZK1 interaction previously attributed exclusively to the canonical binding of the C-terminal SR-BI to PDZ1.
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Affiliation(s)
- Olivier Kocher
- Department of Pathology, Center for Vascular Biology Research, Division of Experimental Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215,
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31
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Fan J, Rone MB, Papadopoulos V. Translocator protein 2 is involved in cholesterol redistribution during erythropoiesis. J Biol Chem 2009; 284:30484-97. [PMID: 19729679 PMCID: PMC2781603 DOI: 10.1074/jbc.m109.029876] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Revised: 08/17/2009] [Indexed: 12/11/2022] Open
Abstract
Translocator protein (TSPO) is an 18-kDa cholesterol- and drug-binding protein conserved from bacteria to humans. While surveying for Tspo-like genes, we identified its paralogous gene, Tspo2, encoding an evolutionarily conserved family of proteins that arose by gene duplications before the divergence of avians and mammals. Comparative analysis of Tspo1 and Tspo2 functions suggested that Tspo2 has become subfunctionalized, typical of duplicated genes, characterized by the loss of diagnostic drug ligand-binding but retention of cholesterol-binding properties, hematopoietic tissue- and erythroid cell-specific distribution, and subcellular endoplasmic reticulum and nuclear membrane localization. Expression of Tspo2 in erythroblasts is strongly correlated with the down-regulation of the enzymes involved in cholesterol biosynthesis. Overexpression of TSPO2 in erythroid cells resulted in the redistribution of intracellular free cholesterol, an essential step in nucleus expulsion during erythrocyte maturation. Taken together, these data identify the TSPO2 family of proteins as mediators of cholesterol redistribution-dependent erythroblast maturation during mammalian erythropoiesis.
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Affiliation(s)
- Jinjiang Fan
- From the Research Institute of the McGill University Health Center and the Departments of Medicine, Biochemistry, and Pharmacology and Therapeutics, McGill University, Montréal, Québec H3A 1A4, Canada
| | - Malena B. Rone
- From the Research Institute of the McGill University Health Center and the Departments of Medicine, Biochemistry, and Pharmacology and Therapeutics, McGill University, Montréal, Québec H3A 1A4, Canada
| | - Vassilios Papadopoulos
- From the Research Institute of the McGill University Health Center and the Departments of Medicine, Biochemistry, and Pharmacology and Therapeutics, McGill University, Montréal, Québec H3A 1A4, Canada
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32
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BNIP3 subfamily BH3-only proteins: mitochondrial stress sensors in normal and pathological functions. Oncogene 2009; 27 Suppl 1:S114-27. [PMID: 19641497 DOI: 10.1038/onc.2009.49] [Citation(s) in RCA: 158] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The BNIP3 subfamily of BH3-only proteins consists of BNIP3 and BNIP3-like (BNIP3L) proteins. These proteins form stable homodimerization complexes that localize to the outer membrane of the mitochondria after cellular stress. This promotes either apoptotic or non-apoptotic cell death such as autophagic cell death. Although the mammalian cells contain both members of this subfamily, the genome of Caenorhabditis elegans codes for a single BNIP3 ortholog, ceBNIP3, which shares homology in the transmembrane (TM) domain and in a conserved region close to the BH3 domain of mammalian BNIP3 protein. The cell death activities of BNIP3 and BNIP3L are determined by either the BH3 domain or the C-terminal TM domain. The TM domain of BNIP3 is unique, as it is capable of autonomous stable dimerization and contributes to mitochondrial localization of BNIP3. In knockout mouse models, BNIP3L was shown to be essential for normal erythrocyte differentiation and hematopoietic homeostasis, whereas BNIP3 plays a role in cellular responses to ischemia/reperfusion injury in the heart. Both BNIP3 and BNIP3L play a role in cellular responses to stress. Under hypoxia, both BNIP3 and BNIP3L expression levels are elevated and contribute to hypoxia-induced cell death. In addition, these proteins play critical roles in disease states. In heart disease, both BNIP3 and BNIP3L play a critical role in cardiomyocyte cell death following ischemic and non-ischemic injuries. In cancer, expression of BNIP3 and BNIP3L is downregulated by promoter hypermethylation or by homozygous deletion of the gene locus in certain cancers, whereas their expression was increased in other cancers. In addition, BNIP3 expression has been correlated with poor prognosis in some cancers. The results reviewed here suggest that BNIP3 and BNIP3L may be novel therapeutic targets for intervention because of their pathological roles in regulating cell death in disease states.
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Fenske SA, Yesilaltay A, Pal R, Daniels K, Rigotti A, Krieger M, Kocher O. Overexpression of the PDZ1 domain of PDZK1 blocks the activity of hepatic scavenger receptor, class B, type I by altering its abundance and cellular localization. J Biol Chem 2008; 283:22097-104. [PMID: 18544532 DOI: 10.1074/jbc.m800029200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
PDZK1 is a four-PDZ domain-containing scaffold protein that, via its first PDZ domain (PDZ1), binds to the C terminus of the high density lipoprotein (HDL) receptor scavenger receptor, class B, type I (SR-BI). Abolishing PDZK1 expression in PDZK1 knock-out (KO) mice leads to a post-transcriptional, tissue-specific decrease in SR-BI protein level and an increase in total plasma cholesterol carried in abnormally large HDL particles. Here we show that, although hepatic overexpression of PDZK1 restored normal SR-BI protein abundance and function in PDZK1 KO mice, hepatic overexpression of only the PDZ1 domain was not sufficient to restore normal SR-BI function. In wild-type mice, overexpression of the PDZ1 domain overcame the activity of the endogenous hepatic PDZK1, resulting in a 75% reduction in hepatic SR-BI protein levels and intracellular mislocalization of the remaining SR-BI. As a consequence, the plasma lipoproteins in PDZ1 transgenic mice resembled those in PDZK1 KO mice (hypercholesterolemia due to large HDL). These results indicate that the PDZ1 domain can control the abundance and localization, and therefore the function, of hepatic SR-BI and that structural features of PDZK1 in addition to its SR-BI-binding PDZ1 domain are required for normal hepatic SR-BI regulation.
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Affiliation(s)
- Sara A Fenske
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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34
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Meurs I, Van Berkel TJ, Van Eck M. Response to Comment on “HDL Cholesterol Levels Are An Important Factor For Determining The Life-Span Of Erythrocytes”. Exp Hematol 2006. [DOI: 10.1016/j.exphem.2006.02.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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35
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Fredericks S, Holt DW. Comment on: HDL cholesterol levels are an important factor for determining the lifespan of erythrocytes. Exp Hematol 2005; 33(11):1309–1319. Exp Hematol 2006; 34:575-6; author reply 577-8. [PMID: 16647561 DOI: 10.1016/j.exphem.2006.02.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2006] [Revised: 01/06/2006] [Accepted: 02/08/2006] [Indexed: 10/24/2022]
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36
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Yesilaltay A, Morales MG, Amigo L, Zanlungo S, Rigotti A, Karackattu SL, Donahee MH, Kozarsky KF, Krieger M. Effects of hepatic expression of the high-density lipoprotein receptor SR-BI on lipoprotein metabolism and female fertility. Endocrinology 2006; 147:1577-88. [PMID: 16410302 DOI: 10.1210/en.2005-1286] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The etiology of human female infertility is often uncertain. The sterility of high-density lipoprotein (HDL) receptor-negative (SR-BI(-/-)) female mice suggests a link between female infertility and abnormal lipoprotein metabolism. SR-BI(-/-) mice exhibit elevated plasma total cholesterol [with normal-sized and abnormally large HDL and high unesterified to total plasma cholesterol (UC:TC) ratio]. We explored the influence of hepatic SR-BI on female fertility by inducing hepatic SR-BI expression in SR-BI(-/-) animals by adenovirus transduction or stable transgenesis. For transgenes, we used both wild-type SR-BI and a double-point mutant, Q402R/Q418R (SR-BI-RR), which is unable to bind to and mediate lipid transfer from wild-type HDL normally, but retains virtually normal lipid transport activities with low-density lipoprotein. Essentially wild-type levels of hepatic SR-BI expression in SR-BI(-/-) mice restored to nearly normal the HDL size distribution and plasma UC:TC ratio, whereas approximately 7- to 40-fold overexpression dramatically lowered plasma TC and increased biliary cholesterol secretion. In contrast, SR-BI-RR overexpression had little effect on SR-BI(+/+) mice, but in SR-BI(-/-) mice, it substantially reduced levels of abnormally large HDL and normalized the UC:TC ratio. In all cases, hepatic transgenic expression restored female fertility. Overexpression in SR-BI(-/-) mice of lecithin:cholesterol acyl transferase, which esterifies plasma HDL cholesterol, did not normalize the UC:TC ratio, probably because the abnormal HDL was a poor substrate, and did not restore fertility. Thus, hepatic SR-BI-mediated lipoprotein metabolism influences murine female fertility, raising the possibility that dyslipidemia might contribute to human female infertility and that targeting lipoprotein metabolism might complement current assisted reproductive technologies.
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Affiliation(s)
- Ayce Yesilaltay
- Department of Biology, Massachusetts Institute of Technology, Cambridge, 02139, USA
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37
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Meurs I, Hoekstra M, van Wanrooij EJA, Hildebrand RB, Kuiper J, Kuipers F, Hardeman MR, Van Berkel TJC, Van Eck M. HDL cholesterol levels are an important factor for determining the lifespan of erythrocytes. Exp Hematol 2006; 33:1309-19. [PMID: 16263415 DOI: 10.1016/j.exphem.2005.07.004] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2005] [Revised: 06/16/2005] [Accepted: 07/11/2005] [Indexed: 11/19/2022]
Abstract
OBJECTIVE Scavenger receptor class B, type I (SR-BI) is a multifunctional receptor that promotes the selective uptake of cholesteryl esters from high-density lipoprotein (HDL). Disruption of SR-BI in mice results in a dramatic increase in HDL cholesterol. Interestingly, mice lacking SR-BI also develop anemia, as evidenced by accumulation of reticulocytes in the circulation. The objective of the current study was to delineate the mechanism underlying development of anemia in the absence of SR-BI. METHODS Expression of important mediators of erythropoiesis, as well as key enzymes in the degradation of erythrocytes, were analyzed using real-time polymerase chain reaction in SR-BI wild-type and SR-BI knockout mice. In addition, in vivo studies were performed using biotinylated erythrocytes to determine erythrocyte survival. RESULTS mRNA expression of TAL-1, GATA-1, FOG-1, erythropoietin receptor, and ferrochelatase, important mediators of erythropoiesis, was increased in spleens of SR-BI-deficient mice. In addition, the relative amount of early Ter119(high)CD71(high) -expressing erythroblasts was increased in SR-BI-deficient spleens. Interestingly, also expression of hemeoxygenase 1 and biliverdin reductase, enzymes involved in the degradation of erythrocytes, was increased. Furthermore, an elevated amount of conjugated bilirubin, the breakdown product of hemoglobin, was found in bile. Using biotinylated erythrocytes, we show that survival of erythrocytes was decreased in SR-BI-deficient mice. Thus, the observed increased erythropoiesis in the SR-BI-deficient mice is most likely a direct response to the reduced erythrocyte lifespan. Finally, we show that increased HDL cholesterol levels due to SR-BI deficiency induce erythrocyte cholesterol:phospholipid ratios, resulting in decreased deformability and increased osmotic fragility, thereby providing an explanation for the observed reduced lifespan. CONCLUSIONS SR-BI is not only essential for HDL cholesterol homeostasis and atherosclerosis susceptibility, but also for maintaining normal erythrocyte lifespan.
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Affiliation(s)
- Illiana Meurs
- Division of Biopharmaceutics, Leiden/Amsterdam Center for Drug Research, Gorlaeus Laboratories, Leiden, The Netherlands
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38
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Yesilaltay A, Kocher O, Rigotti A, Krieger M. Regulation of SR-BI-mediated high-density lipoprotein metabolism by the tissue-specific adaptor protein PDZK1. Curr Opin Lipidol 2005; 16:147-52. [PMID: 15767854 DOI: 10.1097/01.mol.0000162319.54795.e5] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW A novel mechanism for the regulation of lipoprotein receptor activity is providing new insights into the control of lipid metabolism. The tissue-specific adaptors ARH (autosomal recessive hypercholesterolemia) and PDZK1 [where PDZ derives from postsynaptic density protein (PSD-95)/Drosophila discs-large (dlg)/tight-junction protein (ZO1)] have been shown to control the activities of distinct types of lipoprotein receptors in a posttranscriptional fashion, significantly affecting overall lipoprotein metabolism. This review will focus on one of these lipoprotein receptor-adaptor pairs, the high-density lipoprotein receptor SR-BI (scavenger receptor class B, type I) and its adaptor PDZK1. RECENT FINDINGS The PDZ domain-containing adaptor protein PDZK1 has been shown to bind to and control the activity of the high-density lipoprotein receptor SR-BI via a tissue-specific posttranscriptional mechanism. Mice deficient in PDZK1 have elevated plasma cholesterol levels due to the virtually complete hepatic ablation of SR-BI, implicating PDZK1 as a novel regulator of high-density lipoprotein metabolism. SUMMARY The functions of ARH and PDZK1 suggest that other adaptor proteins may be found to control the activities of other cell-surface receptors in a similar tissue-specific fashion. Manipulation of the expression and/or activities of such adaptors might provide new insights into receptor physiology and these adaptors may prove to be attractive targets for pharmaceutical intervention in cholesterol metabolism-related disease processes.
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Affiliation(s)
- Ayce Yesilaltay
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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39
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Van Eck M, Bos IST, Hildebrand RB, Van Rij BT, Van Berkel TJC. Dual role for scavenger receptor class B, type I on bone marrow-derived cells in atherosclerotic lesion development. THE AMERICAN JOURNAL OF PATHOLOGY 2004; 165:785-94. [PMID: 15331403 PMCID: PMC1618614 DOI: 10.1016/s0002-9440(10)63341-x] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The function of scavenger receptor class B, type I (SR-BI) in the liver as a high-density lipoprotein receptor that promotes the selective uptake of cholesteryl esters is well defined. Its role in macrophages, however, is primarily unknown, because it functions in the uptake of (modified) lipoproteins as well as the secretion of cholesterol to high-density lipoproteins. In this study, the biological role of SR-BI on bone marrow-derived cells, including macrophages, in lipid metabolism and atherosclerosis was assessed by selective disruption of SR-BI in bone marrow in two established models of atherosclerosis: low-density lipoprotein (LDL) receptor-deficient mice that develop extensive atherosclerosis on a Western-type diet and wild-type mice that develop fatty streak lesions when fed a high-cholesterol diet containing 0.5% cholate. The presence of SR-BI in bone marrow-derived cells in LDLr-/- mice decreased lesion development after 9 and 12 weeks of Western-type diet feeding, indicating that macrophage SR-BI protects against lesion development. At 6 weeks, no significant effect of SR-BI in bone marrow-derived cells on lesion development was observed. Interestingly, after only 4 weeks of Western-type diet feeding of transplanted LDLr-/- mice and in wild-type mice on a high-cholesterol/cholate diet, the presence of SR-BI in bone marrow-derived cells increased the development of small fatty streak lesions. It thus appears that, depending on the stage of atherosclerotic lesion development, SR-BI in bone marrow-derived cells is either pro-atherogenic or anti-atherogenic, indicating a unique dual role in the pathogenesis of atherosclerosis.
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MESH Headings
- Animals
- Arteriosclerosis/metabolism
- Arteriosclerosis/pathology
- Bone Marrow Cells/cytology
- Bone Marrow Cells/metabolism
- CD36 Antigens
- Cholates/metabolism
- Cholesterol, Dietary
- Diet, Atherogenic
- Female
- Homozygote
- Lipid Metabolism
- Lipoproteins, LDL/metabolism
- Macrophages/physiology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Rats
- Receptors, Immunologic/genetics
- Receptors, Immunologic/physiology
- Receptors, LDL/genetics
- Receptors, LDL/physiology
- Receptors, Scavenger
- Scavenger Receptors, Class B
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Affiliation(s)
- Miranda Van Eck
- Division of Biopharmaceutics, Leiden/Amsterdam Center for Drug Research, Gorlaeus Laboratories, Leiden University, Leiden, The Netherlands.
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40
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Nieland TJF, Chroni A, Fitzgerald ML, Maliga Z, Zannis VI, Kirchhausen T, Krieger M. Cross-inhibition of SR-BI- and ABCA1-mediated cholesterol transport by the small molecules BLT-4 and glyburide. J Lipid Res 2004; 45:1256-65. [PMID: 15102890 DOI: 10.1194/jlr.m300358-jlr200] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Scavenger receptor class B type I (SR-BI) and ABCA1 are structurally dissimilar cell surface proteins that play key roles in HDL metabolism. SR-BI is a receptor that binds HDL with high affinity and mediates both the selective lipid uptake of cholesteryl esters from lipid-rich HDL to cells and the efflux of unesterified cholesterol from cells to HDL. ABCA1 mediates the efflux of unesterified cholesterol and phospholipids from cells to lipid-poor apolipoprotein A-I (apoA-I). The activities of ABCA1 and other ATP binding cassette superfamily members are inhibited by the drug glyburide, and SR-BI-mediated lipid transport is blocked by small molecule inhibitors called BLTs. Here, we show that one BLT, [1-(2-methoxy-phenyl)-3-naphthalen-2-yl-urea] (BLT-4), blocked ABCA1-mediated cholesterol efflux to lipid-poor apoA-I at a potency similar to that for its inhibition of SR-BI (IC(50) approximately 55-60 microM). Reciprocally, glyburide blocked SR-BI-mediated selective lipid uptake and efflux at a potency similar to that for its inhibition of ABCA1 (IC(50) approximately 275-300 microM). As is the case with BLTs, glyburide increased the apparent affinity of HDL binding to SR-BI. The reciprocal inhibition of SR-BI and ABCA1 by BLT-4 and glyburide raises the possibility that these proteins may share similar or common steps in their mechanisms of lipid transport.
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Affiliation(s)
- Thomas J F Nieland
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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41
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Connelly MA, De La Llera-Moya M, Peng Y, Drazul-Schrader D, Rothblat GH, Williams DL. Separation of lipid transport functions by mutations in the extracellular domain of scavenger receptor class B, type I. J Biol Chem 2003; 278:25773-82. [PMID: 12730208 DOI: 10.1074/jbc.m302820200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Scavenger receptor class B, type I (SR-BI) shows a variety of effects on cellular cholesterol metabolism, including increased selective uptake of high density lipoprotein (HDL) cholesteryl ester, stimulation of free cholesterol (FC) efflux from cells to HDL and phospholipid vesicles, and changes in the distribution of plasma membrane FC as evidenced by increased susceptibility to exogenous cholesterol oxidase. Previous studies showed that these multiple effects require the extracellular domain of SR-BI, but not the transmembrane and cytoplasmic domains. To test whether 1) the extracellular domain of SR-BI mediates multiple activities by virtue of discrete functional subdomains, or 2) the multiple activities are, in fact, secondary to and driven by changes in cholesterol flux, the extracellular domain of SR-BI was subjected to insertional mutagenesis by strategically placing an epitope tag into nine sites. These experiments identified four classes of mutants with disruptions at different levels of function. Class 4 mutants showed a clear separation of function between HDL binding, HDL cholesteryl ester uptake, and HDL-dependent FC efflux on one hand and FC efflux to small unilamellar vesicles and an increased cholesterol oxidase-sensitive pool of membrane FC on the other. Selective disruption of the latter two functions provides evidence for multiple functional subdomains in the extracellular receptor domain. Furthermore, these findings uncover a difference in the SR-BI-mediated efflux pathways for FC transfer to HDL acceptors versus phospholipid vesicles. The loss of the cholesterol oxidase-sensitive FC pool and FC efflux to small unilamellar vesicle acceptors in Class 4 mutants suggests that these activities may be mechanistically related.
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MESH Headings
- Amino Acid Sequence
- Animals
- Biological Transport
- CD36 Antigens/chemistry
- CD36 Antigens/genetics
- CD36 Antigens/metabolism
- COS Cells
- Cell Membrane/metabolism
- Cholesterol/metabolism
- Cholesterol Oxidase/metabolism
- Densitometry
- Dose-Response Relationship, Drug
- Epitopes/chemistry
- Flow Cytometry
- Lipid Metabolism
- Lipoproteins, HDL/metabolism
- Membrane Proteins
- Mice
- Microscopy, Fluorescence
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Mutation
- Plasmids/metabolism
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Receptors, Immunologic
- Receptors, Lipoprotein
- Receptors, Scavenger
- Scavenger Receptors, Class B
- Transfection
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Affiliation(s)
- Margery A Connelly
- Department of Pharmacological Sciences, University Medical Center, State University of New York, Stony Brook, New York 11794-8651, USA
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42
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Braun A, Zhang S, Miettinen HE, Ebrahim S, Holm TM, Vasile E, Post MJ, Yoerger DM, Picard MH, Krieger JL, Andrews NC, Simons M, Krieger M. Probucol prevents early coronary heart disease and death in the high-density lipoprotein receptor SR-BI/apolipoprotein E double knockout mouse. Proc Natl Acad Sci U S A 2003; 100:7283-8. [PMID: 12771386 PMCID: PMC165867 DOI: 10.1073/pnas.1237725100] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2002] [Accepted: 04/17/2003] [Indexed: 12/20/2022] Open
Abstract
Mice with homozygous null mutations in the high-density lipoprotein receptor SR-BI (scavenger receptor class B, type I) and apolipoprotein E genes fed a low-fat diet exhibit a constellation of pathologies shared with human atherosclerotic coronary heart disease (CHD): hypercholesterolemia, occlusive coronary atherosclerosis, myocardial infarctions, cardiac dysfunction (heart enlargement, reduced systolic function and ejection fraction, and ECG abnormalities), and premature death (mean age 6 weeks). They also exhibit a block in RBC maturation and abnormally high plasma unesterified-to-total cholesterol ratio (0.8) with associated abnormal lipoprotein morphology (lamellar/vesicular and stacked discoidal particles reminiscent of those in lecithin/cholesterol acyltransferase deficiency and cholestasis). Treatment with the lipid-lowering, antiatherosclerosis, and antioxidation drug probucol extended life to as long as 60 weeks (mean 36 weeks), and at 5-6 weeks of age, virtually completely reversed the cardiac and most RBC pathologies and corrected the unesterified to total cholesterol ratio (0.3) and associated distinctive abnormal lipoprotein morphologies. Manipulation of the timing of administration and withdrawal of probucol could control the onset of death and suggested that critical pathological changes usually occurred in untreated double knockout mice between approximately 3 (weaning) and 5 weeks of age and that probucol delayed heart failure even after development of substantial CHD. The ability of probucol treatment to modulate pathophysiology in the double knockout mice enhances the potential of this murine system for analysis of the pathophysiology of CHD and preclinical testing of new approaches for the prevention and treatment of cardiovascular disease.
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Affiliation(s)
- Anne Braun
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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43
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Pattingre S, De Vries L, Bauvy C, Chantret I, Cluzeaud F, Ogier-Denis E, Vandewalle A, Codogno P. The G-protein regulator AGS3 controls an early event during macroautophagy in human intestinal HT-29 cells. J Biol Chem 2003; 278:20995-1002. [PMID: 12642577 DOI: 10.1074/jbc.m300917200] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
AGS3 contains GoLoco or G-protein regulatory motifs in its COOH-terminal half that stabilize the GDP-bound conformation of the alpha-subunit of the trimeric Gi3 protein. The latter is part of a signaling pathway that controls the lysosomal-autophagic catabolism in human colon cancer HT-29 cells. In the present work we show that the mRNA encoding for AGS3 is expressed in human intestinal cell lines (Caco-2 and HT-29) whatever their state of differentiation. Together with the full-length form, minute amounts of the mRNA encoding a NH2-terminal truncated form of AGS3, previously characterized in cardiac tissues, were also detected. Both the endogenous form of AGS3 and a tagged expressed form have a localization compatible with a role in the Galphai3-dependent control of autophagy. Accordingly, expressing its non-Galphai3-interacting NH2-terminal domain or its Galphai3-interacting COOH-terminal domain reversed the stimulatory role of AGS3 on autophagy. On the basis of biochemical and morphometric analysis, we conclude that AGS3 is involved in an early event during the autophagic pathway probably prior to the formation of the autophagosome. These data demonstrate that AGS3 is a novel partner of the Galphai3 protein in the control of a major catabolic pathway.
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Affiliation(s)
- Sophie Pattingre
- INSERM U504, 16 avenue Paul-Vaillant-Couturier, 94807 Villejuif Cedex, France
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44
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Hyogo H, Roy S, Cohen DE. Restoration of gallstone susceptibility by leptin in C57BL/6J ob/ob mice. J Lipid Res 2003; 44:1232-40. [PMID: 12671032 DOI: 10.1194/jlr.m300029-jlr200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The absence of leptin due to the ob mutation leads to obesity and confers resistance to diet-induced cholesterol gallstone formation in otherwise susceptible C57BL/6J mice. To investigate contributions of obesity and leptin to gallstone susceptibility, C57BL/6J ob/ob mice were treated daily with i.p. saline or recombinant murine leptin at low (1 microgram/g bw) or high (10 microgram/g bw) doses and were pair-fed a lithogenic diet (15% dairy fat, 1.25% cholesterol, 0.5% cholic acid). Weight loss in ob/ob mice increased in proportion to leptin dose, indicating that the lithogenic diet did not impair leptin sensitivity. In a dose-dependent manner, leptin promoted cholesterol crystallization and gallstone formation, which did not occur in saline-treated mice. Notwithstanding, leptin decreased biliary lipid secretion rates without enriching cholesterol in bile. Leptin did not affect bile salt hydrophobicity, but did increase the biliary content of the most abundant molecular species of phosphatidylcholine, 16:0-18:2. Treatment with leptin down-regulated 3-hydroxy-3-methylglutaryl CoA reductase and prevented cholesterol from accumulating in liver. Consistent with increased hepatic clearance, leptin decreased plasma HDL cholesterol concentrations. This was accommodated in liver without up-regulation of cholesterol 7alpha-hydroxylase or Acat. These data suggest that despite the lithogenic diet, endogenous sources constitute a significant proportion of biliary cholesterol during leptin-induced weight loss. Kinetic factors related to cholesterol nucleation, gallbladder contractility, or mucin secretion may have accounted for leptin-induced gallstone formation.
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Affiliation(s)
- Hideyuki Hyogo
- Departments of Medicine, Marion Bessin Liver Research Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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45
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Pattingre S, Bauvy C, Codogno P. Amino acids interfere with the ERK1/2-dependent control of macroautophagy by controlling the activation of Raf-1 in human colon cancer HT-29 cells. J Biol Chem 2003; 278:16667-74. [PMID: 12609989 DOI: 10.1074/jbc.m210998200] [Citation(s) in RCA: 221] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Activation of ERK1/2 stimulates macroautophagy in the human colon cancer cell line HT-29 by favoring the phosphorylation of the Galpha-interacting protein (GAIP) in an amino acid-dependent manner (Ogier-Denis, E., Pattingre, S., El Benna, J., and Codogno, P. (2000) J. Biol. Chem. 275, 39090-39095). Here we show that ERK1/2 activation by aurintricarboxylic acid (ATA) treatment induces the phosphorylation of GAIP in an amino acid-dependent manner. Accordingly, ATA challenge increased the rate of macroautophagy, whereas epidermal growth factor did not significantly affect macroautophagy and GAIP phosphorylation status. In fact, ATA activated the ERK1/2 signaling pathway, whereas epidermal growth factor stimulated both the ERK1/2 pathway and the class I phosphoinositide 3-kinase pathway, known to decrease the rate of macroautophagy. Amino acids interfered with the ATA-induced macroautophagy by inhibiting the activation of the kinase Raf-1. The role of the Ras/Raf-1/ERK1/2 signaling pathway in the GAIP- and amino acid-dependent control of macroautophagy was confirmed in HT-29 cells expressing the Ras(G12V,T35S) mutant. Similar to the protein phosphatase 2A inhibitor okadaic acid, amino acids sustained the phosphorylation of Ser(259), which is involved in the negative regulation of Raf-1. In conclusion, these results add a novel target to the amino acid signaling-dependent control of macroautophagy in intestinal cells.
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Affiliation(s)
- Sophie Pattingre
- INSERM U504, Glycobiologie et Signalisation Cellulaire, 16, avenue Paul-Vaillant-Couturier, 94807 Villejuif Cedex, France
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46
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Viñals M, Xu S, Vasile E, Krieger M. Identification of the N-linked glycosylation sites on the high density lipoprotein (HDL) receptor SR-BI and assessment of their effects on HDL binding and selective lipid uptake. J Biol Chem 2003; 278:5325-32. [PMID: 12429731 DOI: 10.1074/jbc.m211073200] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The murine class B, type I scavenger receptor mSR-BI, a high density lipoprotein (HDL) receptor that mediates selective uptake of HDL lipids, contains 11 potential N-linked glycosylation sites and unknown numbers of both endoglycosidase H-sensitive and -resistant oligosaccharides. We have examined the consequences of mutating each of these sites (Asn --> Gln or Thr --> Ala) on post-translational processing of mSR-BI, cell surface expression, and HDL binding and lipid transport activities. All 11 sites were glycosylated; however, disruption of only two (Asn-108 and Asn-173) substantially altered expression and function. There was very little detectable post-translational processing of these two mutants to endoglycosidase H resistance and very low cell surface expression, suggesting that oligosaccharide modification at these sites apparently plays an important role in endoplasmic reticulum folding and/or intracellular transport. Strikingly, although the low levels of the 108 and 173 mutants that were expressed on the cell surface exhibited a marked reduction in their ability to transfer lipids from HDL to cells, they nevertheless bound nearly normal amounts of HDL. Indeed, the affinity of (125)I-HDL binding to the 173 mutant was similar to that of the wild-type receptor. Thus, N-linked glycosylation can influence both the intracellular transport and lipid-transporter activity of SR-BI. The ability to uncouple the HDL binding and lipid transport activities of mSR-BI by in vitro mutagenesis should provide a powerful tool for further analysis of the mechanism of SR-BI-mediated selective lipid uptake.
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Affiliation(s)
- Marisa Viñals
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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47
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Nieland TJF, Penman M, Dori L, Krieger M, Kirchhausen T. Discovery of chemical inhibitors of the selective transfer of lipids mediated by the HDL receptor SR-BI. Proc Natl Acad Sci U S A 2002; 99:15422-7. [PMID: 12438696 PMCID: PMC137732 DOI: 10.1073/pnas.222421399] [Citation(s) in RCA: 177] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The high-density lipoprotein (HDL) receptor, scavenger receptor, class B, type I (SR-BI), mediates both the selective uptake of lipids, mainly cholesterol esters, from HDL to cells and the efflux of cholesterol from cells to lipoproteins. The mechanism underlying these lipid transfers is distinct from classic receptor-mediated endocytosis, but it remains poorly understood. To investigate SR-BI's mechanism of action and in vivo function, we developed a high-throughput screen to identify small molecule inhibitors of SR-BI-mediated lipid transfer in intact cells. We identified five compounds that in the low nanomolar to micromolar range block lipid transport (BLTs), both selective uptake and efflux. The effects of these compounds were highly specific to the SR-BI pathway, because they didn't interfere with receptor-mediated endocytosis or with other forms of intracellular vesicular traffic. Surprisingly, all five BLTs enhanced, rather than inhibited, HDL binding by increasing SR-BI's binding affinity for HDL (decreased dissociation rates). Thus, the BLTs provide strong evidence for a mechanistic coupling between HDL binding and lipid transport and may serve as a starting point for the development of pharmacologically useful modifiers of SR-BI activity and, thus, HDL metabolism.
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Affiliation(s)
- Thomas J F Nieland
- Department of Cell Biology, Harvard Medical School, and Center for Blood Research, Boston, MA 02115-5701, USA
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48
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Liu B, Krieger M. Highly purified scavenger receptor class B, type I reconstituted into phosphatidylcholine/cholesterol liposomes mediates high affinity high density lipoprotein binding and selective lipid uptake. J Biol Chem 2002; 277:34125-35. [PMID: 12110672 DOI: 10.1074/jbc.m204265200] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The murine class B, type I scavenger receptor mSR-BI is a high and low density lipoprotein (HDL and LDL) receptor that mediates selective uptake of cholesteryl esters. Here we describe a reconstituted phospholipid/cholesterol liposome assay of the binding and selective uptake activities of SR-BI derived from detergent-solubilized cells. The assay, employing lysates from epitope-tagged receptor (mSR-BI-t1)-expressing mammalian and insect cells, recapitulated many features of SR-BI activity in intact cells, including high affinity and saturable (125)I-HDL binding, selective lipid uptake from [(3)H]cholesteryl ether-labeled HDL, and poor inhibition of HDL receptor activity by LDL. The novel properties of a mutated receptor (Q402R/Q418R, normal LDL binding but loss of most HDL binding) were reproduced in the assay, as was the ability of the SR-BI homologue CD36 to bind HDL but not mediate efficient lipid uptake. In this assay, essentially homogeneously pure mSR-BI-t1, prepared by single-step immunoaffinity chromatography, mediated high affinity HDL binding and efficient selective lipid uptake from HDL. Thus, SR-BI-mediated HDL binding and selective lipid uptake are intrinsic properties of the receptor that do not require the intervention of other proteins or specific cellular structures or compartments.
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Affiliation(s)
- Bin Liu
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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