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Li Y, Xiong Z, Jiang WL, Tian D, Zhou H, Hou Q, Xiao L, Zhang M, Huang L, Zhong L, Zhou L, Zeng GG. An innovative viewpoint on the existing and prospectiveness of SR-B1. Curr Probl Cardiol 2024; 49:102226. [PMID: 38040207 DOI: 10.1016/j.cpcardiol.2023.102226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Accepted: 11/28/2023] [Indexed: 12/03/2023]
Abstract
Scavenger Receptor Class B Type 1 (SR-B1), a receptor protein expressed on the cell membrane, plays a crucial role in the metabolism and transport of cholesterol and other lipids, contributing significantly to the homeostasis of lipid levels within the body. Bibliometric analysis involves the application of mathematical and statistical methods to quantitatively analyze different types of documents. It involves the analysis of structural and temporal trends in scholarly articles, coupled with the identification of subject emphasis and variations. Through a bibliometric analysis, this study examines the historical background, current research trends, and future directions in the exploration of SR-B1. By offering insights into the research status and development of SR-B1, this paper aims to assist researchers in identifying novel pathways and areas of investigation in this field of study. Following the screening process, it can be concluded that research on SR-B1 has consistently remained a topic of significant interest over the past 17 years. Interestingly, SR-B1 has recently garnered attention in areas beyond its traditional research focus, including the field of cancer. The primary objective of this review is to provide a concise and accessible overview of the development process of SR-B1 that can help readers who are not well-versed in SR-B1 research quickly grasp its key aspects. Furthermore, this review aims to offer insights and suggestions to researchers regarding potential future research directions and areas of emphasis relating to SR-B1.
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Affiliation(s)
- Yonggui Li
- The Second Affiliated Hospital, Department of Digestive Internal Medicine, Hengyang Medical School, University of South China, Hengyang, Hunan, China
| | - Zhijie Xiong
- The Second Affiliated Hospital, Department of Digestive Internal Medicine, Hengyang Medical School, University of South China, Hengyang, Hunan, China
| | - Wan-Li Jiang
- Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, Hunan International Scientific and Technological Cooperation Base of Arteriosclerotic Disease, Hengyang Medical School, University of South China, Hengyang, Hunan 421001, China; Departments of Clinical Medicine, Hengyang Medical College, University of South China, Hengyang, Hunan 421001, China
| | - Dandan Tian
- School of Nursing, Hengyang Medical College, University of South China, Hengyang, Hunan 421001, China
| | - Haiyou Zhou
- The Second Affiliated Hospital, Department of Digestive Internal Medicine, Hengyang Medical School, University of South China, Hengyang, Hunan, China; Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, Hunan International Scientific and Technological Cooperation Base of Arteriosclerotic Disease, Hengyang Medical School, University of South China, Hengyang, Hunan 421001, China; 2020 Grade Excellent Doctor Class of Hengyang Medical College, University of South China, Hengyang, Hunan 421001, China
| | - Qin Hou
- Hengyang Medical College, University of South China, Hengyang, Hunan 421001, China
| | - Liang Xiao
- The Second Affiliated Hospital, Department of Digestive Internal Medicine, Hengyang Medical School, University of South China, Hengyang, Hunan, China; Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, Hunan International Scientific and Technological Cooperation Base of Arteriosclerotic Disease, Hengyang Medical School, University of South China, Hengyang, Hunan 421001, China; 2020 Grade Excellent Doctor Class of Hengyang Medical College, University of South China, Hengyang, Hunan 421001, China
| | - Mengjie Zhang
- Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, Hunan International Scientific and Technological Cooperation Base of Arteriosclerotic Disease, Hengyang Medical School, University of South China, Hengyang, Hunan 421001, China; Departments of Clinical Medicine, Hengyang Medical College, University of South China, Hengyang, Hunan 421001, China
| | - Liubin Huang
- Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, Hunan International Scientific and Technological Cooperation Base of Arteriosclerotic Disease, Hengyang Medical School, University of South China, Hengyang, Hunan 421001, China; Departments of Clinical Medicine, Hengyang Medical College, University of South China, Hengyang, Hunan 421001, China
| | - Lianping Zhong
- The Second Affiliated Hospital, Department of Digestive Internal Medicine, Hengyang Medical School, University of South China, Hengyang, Hunan, China; Department of Gastroenterology, the Second Affiliated Hospital, Hengyang Medical School, University of South China, Hengyang, China
| | - Li Zhou
- Department of Pathology, Chongqing Public Health Medical Center, Southwest University Public Health Hospital, Chongqing, China
| | - Guang-Gui Zeng
- The Second Affiliated Hospital, Department of Digestive Internal Medicine, Hengyang Medical School, University of South China, Hengyang, Hunan, China; Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, Hunan International Scientific and Technological Cooperation Base of Arteriosclerotic Disease, Hengyang Medical School, University of South China, Hengyang, Hunan 421001, China; 2020 Grade Excellent Doctor Class of Hengyang Medical College, University of South China, Hengyang, Hunan 421001, China.
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2
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Puddu A, Montecucco F, Maggi D. Caveolin-1 and Atherosclerosis: Regulation of LDLs Fate in Endothelial Cells. Int J Mol Sci 2023; 24:ijms24108869. [PMID: 37240214 DOI: 10.3390/ijms24108869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 04/28/2023] [Accepted: 05/15/2023] [Indexed: 05/28/2023] Open
Abstract
Caveolae are 50-100 nm cell surface plasma membrane invaginations observed in terminally differentiated cells. They are characterized by the presence of the protein marker caveolin-1. Caveolae and caveolin-1 are involved in regulating several signal transduction pathways and processes. It is well recognized that they have a central role as regulators of atherosclerosis. Caveolin-1 and caveolae are present in most of the cells involved in the development of atherosclerosis, including endothelial cells, macrophages, and smooth muscle cells, with evidence of either pro- or anti-atherogenic functions depending on the cell type examined. Here, we focused on the role of caveolin-1 in the regulation of the LDLs' fate in endothelial cells.
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Affiliation(s)
- Alessandra Puddu
- Department of Internal Medicine, University of Genoa, Viale Benedetto XV, 6, 16132 Genoa, Italy
| | - Fabrizio Montecucco
- Department of Internal Medicine, University of Genoa, Viale Benedetto XV, 6, 16132 Genoa, Italy
- IRCCS Ospedale Policlinico San Martino Genoa, Italian Cardiovascular Network, Largo Rosanna Benzi 10, 16132 Genoa, Italy
| | - Davide Maggi
- Department of Internal Medicine, University of Genoa, Viale Benedetto XV, 6, 16132 Genoa, Italy
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3
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Luo S, Yang M, Zhao H, Han Y, Jiang N, Yang J, Chen W, Li C, Liu Y, Zhao C, Sun L. Caveolin-1 Regulates Cellular Metabolism: A Potential Therapeutic Target in Kidney Disease. Front Pharmacol 2021; 12:768100. [PMID: 34955837 PMCID: PMC8703113 DOI: 10.3389/fphar.2021.768100] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 11/08/2021] [Indexed: 01/09/2023] Open
Abstract
The kidney is an energy-consuming organ, and cellular metabolism plays an indispensable role in kidney-related diseases. Caveolin-1 (Cav-1), a multifunctional membrane protein, is the main component of caveolae on the plasma membrane. Caveolae are represented by tiny invaginations that are abundant on the plasma membrane and that serve as a platform to regulate cellular endocytosis, stress responses, and signal transduction. However, caveolae have received increasing attention as a metabolic platform that mediates the endocytosis of albumin, cholesterol, and glucose, participates in cellular metabolic reprogramming and is involved in the progression of kidney disease. It is worth noting that caveolae mainly depend on Cav-1 to perform the abovementioned cellular functions. Furthermore, the mechanism by which Cav-1 regulates cellular metabolism and participates in the pathophysiology of kidney diseases has not been completely elucidated. In this review, we introduce the structure and function of Cav-1 and its functions in regulating cellular metabolism, autophagy, and oxidative stress, focusing on the relationship between Cav-1 in cellular metabolism and kidney disease; in addition, Cav-1 that serves as a potential therapeutic target for treatment of kidney disease is also described.
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Affiliation(s)
- Shilu Luo
- Department of Nephrology, The Second Xiangya Hospital, Central South University, Changsha, China.,Hunan Key Laboratory of Kidney Disease and Blood Purification, Changsha, China
| | - Ming Yang
- Department of Nephrology, The Second Xiangya Hospital, Central South University, Changsha, China.,Hunan Key Laboratory of Kidney Disease and Blood Purification, Changsha, China
| | - Hao Zhao
- Department of Nephrology, The Second Xiangya Hospital, Central South University, Changsha, China.,Hunan Key Laboratory of Kidney Disease and Blood Purification, Changsha, China
| | - Yachun Han
- Department of Nephrology, The Second Xiangya Hospital, Central South University, Changsha, China.,Hunan Key Laboratory of Kidney Disease and Blood Purification, Changsha, China
| | - Na Jiang
- Department of Nephrology, The Second Xiangya Hospital, Central South University, Changsha, China.,Hunan Key Laboratory of Kidney Disease and Blood Purification, Changsha, China
| | - Jinfei Yang
- Department of Nephrology, The Second Xiangya Hospital, Central South University, Changsha, China.,Hunan Key Laboratory of Kidney Disease and Blood Purification, Changsha, China
| | - Wei Chen
- Department of Nephrology, The Second Xiangya Hospital, Central South University, Changsha, China.,Hunan Key Laboratory of Kidney Disease and Blood Purification, Changsha, China
| | - Chenrui Li
- Department of Nephrology, The Second Xiangya Hospital, Central South University, Changsha, China.,Hunan Key Laboratory of Kidney Disease and Blood Purification, Changsha, China
| | - Yan Liu
- Department of Nephrology, The Second Xiangya Hospital, Central South University, Changsha, China.,Hunan Key Laboratory of Kidney Disease and Blood Purification, Changsha, China
| | - Chanyue Zhao
- Department of Nephrology, The Second Xiangya Hospital, Central South University, Changsha, China.,Hunan Key Laboratory of Kidney Disease and Blood Purification, Changsha, China
| | - Lin Sun
- Department of Nephrology, The Second Xiangya Hospital, Central South University, Changsha, China.,Hunan Key Laboratory of Kidney Disease and Blood Purification, Changsha, China
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4
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Trigatti BL. Pcpe2: A New Partner for the Scavenger Receptor Class B Type I in High-Density Lipoprotein Selective Lipid Uptake. Arterioscler Thromb Vasc Biol 2021; 41:2726-2729. [PMID: 34615373 DOI: 10.1161/atvbaha.121.316971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Bernardo L Trigatti
- Department of Biochemistry and Biomedical Sciences, Thrombosis and Atherosclerosis Research Institute, McMaster University and Hamilton Health Sciences, Hamilton, Ontario, Canada
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5
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Tan M, Ye J, Zhao M, Ke X, Huang K, Liu H. Recent developments in the regulation of cholesterol transport by natural molecules. Phytother Res 2021; 35:5623-5633. [PMID: 34327759 DOI: 10.1002/ptr.7198] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Revised: 06/02/2021] [Accepted: 06/07/2021] [Indexed: 11/10/2022]
Abstract
The dysregulation of cholesterol metabolism is a high-risk factor for non-alcoholic fatty liver disease (NAFLD), dyslipidemia, and atherosclerosis (AS). Cholesterol transport maintains whole-body cholesterol homeostasis. Low-density apolipoprotein receptor (LDLR) mediates cholesterol uptake in cells and plays an important role in the primary route of circulatory cholesterol clearance in liver cells. Caveolins 1 is an integral membrane protein and shuttle between the cytoplasm and cell membrane. Caveolins 1 not only plays a role in promoting cholesterol absorption in cells but also in the transport of cellular cholesterol efflux by interacting with the ATP-binding cassette transporter A1 (ABCA1) and scavenger receptor class B type I (SR-BI). These proteins, which are associated with reverse cholesterol transport (RCT), are potential therapeutic targets for NAFLD and AS. Many studies have indicated that natural products have lipid-lowering effects. Moreover, natural molecules, derived from natural products, have the potential to be developed into novel drugs. However, the mechanisms underlying the regulation of cholesterol transport by natural molecules have not yet been adequately investigated. In this review, we briefly describe the process of cholesterol transport and summarize the mechanisms by which molecules regulate cholesterol transport. This article provides an overview of recent studies and focuses on the potential therapeutic effects of natural molecules; however, further high-quality studies are needed to firmly establish the clinical efficacies of natural molecules.
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Affiliation(s)
- Meiao Tan
- Chongqing Traditional Chinese Medicine Hospital, Chongqing, China.,First Clinical Medical College, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Jintong Ye
- First Clinical Medical College, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Min Zhao
- Guangzhou Liwan District Traditional Chinese Medicine Hospital, Guangzhou, China
| | - Xuehong Ke
- The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Keer Huang
- The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Huabao Liu
- Chongqing Traditional Chinese Medicine Hospital, Chongqing, China
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6
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Tian J, Popal MS, Huang R, Zhang M, Zhao X, Zhang M, Song X. Caveolin as a Novel Potential Therapeutic Target in Cardiac and Vascular Diseases: A Mini Review. Aging Dis 2020; 11:378-389. [PMID: 32257548 PMCID: PMC7069461 DOI: 10.14336/ad.2019.09603] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 06/03/2019] [Indexed: 12/27/2022] Open
Abstract
Caveolin, a structural protein of caveolae, play roles in the regulation of endothelial function, cellular lipid homeostasis, and cardiac function by affecting the activity and biogenesis of nitric oxide, and by modulating signal transduction pathways that mediate inflammatory responses and oxidative stress. In this review, we present the role of caveolin in cardiac and vascular diseases and the relevant signaling pathways involved. Furthermore, we discuss a novel therapeutic perspective comprising crosstalk between caveolin and autophagy.
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Affiliation(s)
- Jinfan Tian
- 1 Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing 100029, China
| | - Mohammad Sharif Popal
- 2 Department of Cardiac Surgery, Beijing Anzhen Hospital, Capital Medical University, Beijing 100029, China
| | - RongChong Huang
- 3 Department of Cardiology, Beijing Friendship Hospital, Capital Medical University, Beijing 100010, China
| | - Min Zhang
- 1 Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing 100029, China
| | - Xin Zhao
- 1 Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing 100029, China
| | - Mingduo Zhang
- 1 Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing 100029, China
| | - Xiantao Song
- 1 Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing 100029, China
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7
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Huang K, Dang Y, Zhang P, Shen C, Sui X, Xia G, Qin Y, Jiao X, Wang C, Huo R, Chen ZJ. CAV1 regulates primordial follicle formation via the Notch2 signalling pathway and is associated with premature ovarian insufficiency in humans. Hum Reprod 2019; 33:2087-2095. [PMID: 30304446 DOI: 10.1093/humrep/dey299] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 09/19/2018] [Indexed: 11/13/2022] Open
Abstract
STUDY QUESTION What is the function of CAV1 in folliculogenesis and female reproduction? SUMMARY ANSWER CAV1 regulates germline cyst breakdown and primordial follicle (PF) formation in mice, and CAV1 mutation may be related to premature ovarian insufficiency (POI). WHAT IS KNOWN ALREADY Pre-granulosa cells are essential for the establishment of the PF pool, which determines female fertility and reproductive lifespan. Cav1 participates in vascularization in fetal mouse ovaries. However, the role of CAV1 in early folliculogenesis and POI pathogenesis remains unclear. STUDY DESIGN, SIZE, DURATION Cav1 function was investigated in mice and Human Embryonic Kidney 293 cells. Ovaries (six per group) were randomly assigned to Cav1-vivo-morpholino, control and control-morpholino groups, and all experiments were repeated at least three times. To investigate CAV1 mutations in women, 200 Chinese women with POI and 200 control individuals with regular menstrual cycles and normal endocrine profiles were recruited from the Center for Reproductive Medicine of Shandong University between September 2012 and December 2013. PARTICIPANTS/MATERIALS, SETTING, METHODS Wild-type CD1 mice, Lgr5-EGFP-ires-CreERT2 (Lgr5-KI) reporter mice and Human Embryonic Kidney 293 cells were used for these experiments. Protein expression was detected by Western blot, and quantitative RT-PCR was used to detect gene expression. The expression pattern of CAV1 in mouse ovaries and the phenotype of Cav1 deficiency in mice were detected by immunofluorescence. Pre-granulosa cell proliferation in ovaries was detected by bromodeoxyuridine (BrdU) assay and immunofluorescence. The coding region of the CAV1 gene was sequenced in 200 women with POI and 200 controls. The functional effect of the novel mutation c.142 G > C (p.Glu48Gln) was investigated by Cell Counting Kit-8 (CCK8) assays and Western blot. MAIN RESULTS AND THE ROLE OF CHANCE We confirmed that Cav1 deficiency in mouse ovary induced by CAV1-vivo-morpholino resulted in more multi-oocyte follicles than in the control and control-morpholino groups (P < 0.01). Suppression of Cav1 decreased Leucine rich repeat containing G protein coupled receptor 5 (Lgr5)-positive cell proliferation (P < 0.01) and reduced the number of Lgr5 and Forkhead box L2 (Foxl2) double-positive cells (P < 0.01). Furthermore, suppression of Cav1 inhibited ovarian epithelial Lgr5-positive cell proliferation and differentiation through the Notch2 signalling pathway. Two of the POI women carried novel CAV1 mutations (c.45 C > G synonymous and c.142 G > C [Glu48Gln]). The deleterious effect of p.Glu48Gln was corroborated by showing that it adversely affected the function of CAV1 in cell proliferation and NOTCH2 expression in HEK293FT cells. LARGE-SCALE DATA N/A. LIMITATIONS, REASONS FOR CAUTION The novel Glu48Gln mutation was only detected in one of 200 POI patients and we were unable to investigate its effects in the ovary. WIDER IMPLICATIONS OF THE FINDINGS The identification of CAV1 as a potentially causative gene for POI provides a theoretical basis to devise treatments for POI in women. STUDY FUNDING/COMPETING INTEREST(S) This work was supported by the National Basic Research Program of China (973 Programs: 2012CB944700; 2013CB945501; 2013CB911400; 2014CB943202), the National Key Research and Development Program of China (2016YFC1000604, 2017YFC1001301), the State Key Program of National Natural Science Foundation of China (81430029), and the National Natural Science Foundation of China (31571540, 81522018, 81471509, 81601245, 81701406, 81571406). The authors declare no competing financial interests.
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Affiliation(s)
- Kun Huang
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Yujie Dang
- Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Center for Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, China.,National Research Center for Assisted Reproductive Technology and Reproductive Genetics; The Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education; Shandong Provincial Key Laboratory of Reproductive Medicine, Jinan, China.,Center for Reproductive Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University; Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics, Shanghai, China
| | - Pan Zhang
- State Key Laboratory of Reproductive Medicine, Department of Histology and Embryology, Nanjing Medical University, Nanjing, China
| | - Cong Shen
- State Key Laboratory of Reproductive Medicine, Department of Histology and Embryology, Nanjing Medical University, Nanjing, China
| | - Xuesong Sui
- State Key Laboratory of Reproductive Medicine, Department of Histology and Embryology, Nanjing Medical University, Nanjing, China
| | - Guoliang Xia
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Yingying Qin
- Center for Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, China.,National Research Center for Assisted Reproductive Technology and Reproductive Genetics; The Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education; Shandong Provincial Key Laboratory of Reproductive Medicine, Jinan, China
| | - Xue Jiao
- Center for Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, China.,National Research Center for Assisted Reproductive Technology and Reproductive Genetics; The Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education; Shandong Provincial Key Laboratory of Reproductive Medicine, Jinan, China
| | - Chao Wang
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Ran Huo
- State Key Laboratory of Reproductive Medicine, Department of Histology and Embryology, Nanjing Medical University, Nanjing, China
| | - Zi-Jiang Chen
- Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Center for Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, China.,National Research Center for Assisted Reproductive Technology and Reproductive Genetics; The Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education; Shandong Provincial Key Laboratory of Reproductive Medicine, Jinan, China.,Center for Reproductive Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University; Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics, Shanghai, China
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8
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Nizam R, Al-Ozairi E, Goodson JM, Melhem M, Davidsson L, Alkhandari H, Al Madhoun A, Shamsah S, Qaddoumi M, Alghanim G, Alhasawi N, Abu-Farha M, Abubaker J, Shi P, Hartman ML, Tavares M, Bitar M, Ali H, Arefanian H, Devarajan S, Al-Refaei F, Alsmadi O, Tuomilehto J, Al-Mulla F. Caveolin-1 Variant Is Associated With the Metabolic Syndrome in Kuwaiti Children. Front Genet 2018; 9:689. [PMID: 30622557 PMCID: PMC6308323 DOI: 10.3389/fgene.2018.00689] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 12/11/2018] [Indexed: 12/18/2022] Open
Abstract
Caveolin-1 (CAV1) variants have been suggested to be associated with obesity and related metabolic disorders, but information based on human studies is limited. In the present study, we aimed to investigate the potential association between the CAV1 rs1997623 C/A variant and metabolic syndrome (MetS) in Kuwaiti children. DNA from saliva samples collected from 1313 Kuwaiti children (mean age: 12 years) were genotyped using the TaqMan SNP genotyping assay. The classification of MetS was based on the presence/absence of four indicators; (1) central obesity, (2) elevated systolic or diastolic blood pressure, (3) low salivary high-density lipoprotein cholesterol (HDLC), and (4) high salivary glucose. In this study, children with MetS scored ≥3, children in the intermediate metabolic group scored 1 or 2 and children without MetS scored 0. About one-third of the children were obese. A total of 246 children (18.7%) were classified as having MetS; 834 children (63.5%) were in the intermediate metabolic group, and 233 children (17.7%) had no indication of MetS. Obesity was highly prevalent in the MetS group (91.9%) while 26.8% of children were obese in the intermediate metabolic group. None of the children were obese in the group without MetS. Analysis of the CAV1 rs1997623 variant revealed a significant association of the A-allele (p = 0.01, Odds Ratio (OR) = 1.66) and the heterozygous CA-genotype (p = 0.005, OR = 1.88) with MetS. Consistently, the A-allele (p = 0.002, OR = 1.71) and CA-genotype (p = 0.005, OR = 1.70) also showed significant association with the intermediate metabolic group. Furthermore, the A-allele (p = 0.01, OR = 1.33) and the CA-genotype (p = 0.008, OR = 1.55) were associated with low levels of saliva HDLC. Individuals who were heterozygous or homozygous for the variant (CA/AA) showed significantly lower levels of high HDLC compared to those harboring the CC-genotype (p = 0.023). Our study revealed a novel association of the CAV1 rs1997623 variant with the MetS and with low saliva HDLC levels in young Kuwaiti children and indicated the need for further in-depth studies to unravel the role of CAV1 gene in the genetic etiology of MetS.
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Affiliation(s)
- Rasheeba Nizam
- Functional Genomics Unit, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Ebaa Al-Ozairi
- Clinical Division, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Jo Max Goodson
- Applied Oral Sciences, The Forsyth Institute, Cambridge, MA, United States
| | - Motesam Melhem
- Functional Genomics Unit, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Lena Davidsson
- Family Medicine and Pediatric Unit, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Hessa Alkhandari
- Family Medicine and Pediatric Unit, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Ashraf Al Madhoun
- Functional Genomics Unit, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Sara Shamsah
- Faculty of Allied Health Sciences, Kuwait University, Kuwait City, Kuwait
| | - Malak Qaddoumi
- Functional Genomics Unit, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Ghazi Alghanim
- Functional Genomics Unit, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Nouf Alhasawi
- Functional Genomics Unit, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Mohamed Abu-Farha
- Biochemistry and Molecular Biology Unit, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Jehad Abubaker
- Biochemistry and Molecular Biology Unit, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Ping Shi
- Applied Oral Sciences, The Forsyth Institute, Cambridge, MA, United States
| | - Mor-Li Hartman
- Applied Oral Sciences, The Forsyth Institute, Cambridge, MA, United States
| | - Mary Tavares
- Applied Oral Sciences, The Forsyth Institute, Cambridge, MA, United States
| | - Milad Bitar
- Faculty of Medicine, Kuwait University, Kuwait City, Kuwait
| | - Hamad Ali
- Faculty of Allied Health Sciences, Kuwait University, Kuwait City, Kuwait
| | | | - Sriraman Devarajan
- National Dasman Diabetes Biobank, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Faisal Al-Refaei
- Clinical Division, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Osama Alsmadi
- Cell Therapy and Applied Genomics, King Hussein Cancer Center, Amman, Jordan
| | | | - Fahd Al-Mulla
- Functional Genomics Unit, Dasman Diabetes Institute, Kuwait City, Kuwait
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9
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Smith JN, Edgar JM, Balk JM, Iftikhar M, Fong JC, Olsen TJ, Fishman DA, Majumdar S, Weiss GA. Directed evolution and biophysical characterization of a full-length, soluble, human caveolin-1 variant. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2018; 1866:963-972. [PMID: 29857161 DOI: 10.1016/j.bbapap.2018.05.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 05/16/2018] [Accepted: 05/24/2018] [Indexed: 12/22/2022]
Abstract
Protein engineering by directed evolution can alter proteins' structures, properties, and functions. However, membrane proteins, despite their importance to living organisms, remain relatively unexplored as targets for protein engineering and directed evolution. This gap in capabilities likely results from the tendency of membrane proteins to aggregate and fail to overexpress in bacteria cells. For example, the membrane protein caveolin-1 has been implicated in many cell signaling pathways and diseases, yet the full-length protein is too aggregation-prone for detailed mutagenesis, directed evolution, and biophysical characterization. Using a phage-displayed library of full-length caveolin-1 variants, directed evolution with alternating subtractive and functional selections isolated a full-length, soluble variant, termed cavsol, for expression in E. coli. Cavsol folds correctly and binds to its known protein ligands HIV gp41, the catalytic domain of cAMP-dependent protein kinase A, and the polymerase I and transcript release factor. As expected, cavsol does not bind off-target proteins. Cellular studies show that cavsol retains the parent protein's ability to localize at the cellular membrane. Unlike truncated versions of caveolin, cavsol forms large, oligomeric complexes consisting of approximately >50 monomeric units without requiring additional cellular components. Cavsol's secondary structure is a mixture of α-helices and β-strands. Isothermal titration calorimetry experiments reveal that cavsol binds to gp41 and PKA with low micromolar binding affinity (KD). In addition to the insights into caveolin structure and function, the approach applied here could be generalized to other membrane proteins.
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Affiliation(s)
- Joshua N Smith
- Department of Molecular Biology and Biochemistry,University of California, Irvine, CA 92697, USA
| | - Joshua M Edgar
- Department of Chemistry, University of California, Irvine, CA 92697, USA
| | - J Mark Balk
- Department of Chemistry, University of California, Irvine, CA 92697, USA
| | - Mariam Iftikhar
- Department of Chemistry, University of California, Irvine, CA 92697, USA
| | - Jessica C Fong
- Department of Pharmaceutical Sciences, University of California, Irvine, CA 92697, USA
| | - Tivoli J Olsen
- Department of Chemistry, University of California, Irvine, CA 92697, USA
| | - Dmitry A Fishman
- Department of Chemistry, University of California, Irvine, CA 92697, USA
| | - Sudipta Majumdar
- Department of Chemistry, University of California, Irvine, CA 92697, USA
| | - Gregory A Weiss
- Department of Molecular Biology and Biochemistry,University of California, Irvine, CA 92697, USA; Department of Chemistry, University of California, Irvine, CA 92697, USA.
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10
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Windheim M. Interleukin-1-induced gene expression requires the membrane-raft-dependent internalization of the interleukin-1 receptor. Cell Signal 2016; 28:1520-9. [PMID: 27327966 DOI: 10.1016/j.cellsig.2016.06.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 06/16/2016] [Accepted: 06/16/2016] [Indexed: 12/27/2022]
Affiliation(s)
- Mark Windheim
- Institute of Biochemistry, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
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11
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Aho V, Ollila HM, Kronholm E, Bondia-Pons I, Soininen P, Kangas AJ, Hilvo M, Seppälä I, Kettunen J, Oikonen M, Raitoharju E, Hyötyläinen T, Kähönen M, Viikari JSA, Härmä M, Sallinen M, Olkkonen VM, Alenius H, Jauhiainen M, Paunio T, Lehtimäki T, Salomaa V, Orešič M, Raitakari OT, Ala-Korpela M, Porkka-Heiskanen T. Prolonged sleep restriction induces changes in pathways involved in cholesterol metabolism and inflammatory responses. Sci Rep 2016; 6:24828. [PMID: 27102866 PMCID: PMC4840329 DOI: 10.1038/srep24828] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2015] [Accepted: 04/05/2016] [Indexed: 12/22/2022] Open
Abstract
Sleep loss and insufficient sleep are risk factors for cardiometabolic diseases, but data on how insufficient sleep contributes to these diseases are scarce. These questions were addressed using two approaches: an experimental, partial sleep restriction study (14 cases and 7 control subjects) with objective verification of sleep amount, and two independent epidemiological cohorts (altogether 2739 individuals) with questions of sleep insufficiency. In both approaches, blood transcriptome and serum metabolome were analysed. Sleep loss decreased the expression of genes encoding cholesterol transporters and increased expression in pathways involved in inflammatory responses in both paradigms. Metabolomic analyses revealed lower circulating large HDL in the population cohorts among subjects reporting insufficient sleep, while circulating LDL decreased in the experimental sleep restriction study. These findings suggest that prolonged sleep deprivation modifies inflammatory and cholesterol pathways at the level of gene expression and serum lipoproteins, inducing changes toward potentially higher risk for cardiometabolic diseases.
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Affiliation(s)
- Vilma Aho
- Department of Physiology, Faculty of Medicine, University of Helsinki, Finland
| | - Hanna M Ollila
- Department of Physiology, Faculty of Medicine, University of Helsinki, Finland
- Genomics and Biomarkers unit and Institute for Molecular Medicine FIMM, National Institute for Health and Welfare, Helsinki, Finland
- Department of Psychiatry, University of Helsinki and Helsinki University Hospital, Finland
- Stanford University Center for Sleep Sciences, Palo Alto, CA, USA
| | - Erkki Kronholm
- Department of Chronic Disease Prevention, Population Studies Unit, National Institute for Health and Welfare, Turku, Finland
| | - Isabel Bondia-Pons
- VTT Technical Research Centre of Finland, Espoo, Finland
- Steno Diabetes Center A/S, Gentofte, Denmark
| | - Pasi Soininen
- Computational Medicine, Institute of Health Sciences, University of Oulu, Oulu, Finland
- NMR Metabolomics Laboratory, School of Pharmacy, University of Eastern Finland, Kuopio, Finland
| | - Antti J Kangas
- Computational Medicine, Institute of Health Sciences, University of Oulu, Oulu, Finland
| | - Mika Hilvo
- VTT Technical Research Centre of Finland, Espoo, Finland
| | - Ilkka Seppälä
- Department of Clinical Chemistry, Fimlab Laboratories, and University of Tampere, School of Medicine, Tampere, Finland
| | - Johannes Kettunen
- Genomics and Biomarkers unit and Institute for Molecular Medicine FIMM, National Institute for Health and Welfare, Helsinki, Finland
- Computational Medicine, Institute of Health Sciences, University of Oulu, Oulu, Finland
- NMR Metabolomics Laboratory, School of Pharmacy, University of Eastern Finland, Kuopio, Finland
| | - Mervi Oikonen
- Research Centre of Applied and Preventive Cardiovascular Medicine, University of Turku, Turku, Finland
| | - Emma Raitoharju
- Department of Clinical Chemistry, Fimlab Laboratories, and University of Tampere, School of Medicine, Tampere, Finland
| | - Tuulia Hyötyläinen
- VTT Technical Research Centre of Finland, Espoo, Finland
- Steno Diabetes Center A/S, Gentofte, Denmark
| | - Mika Kähönen
- Department of Clinical Physiology, University of Tampere and Tampere University Hospital, Tampere, Finland
| | - Jorma S A Viikari
- Department of Medicine, University of Turku, and Division of Medicine, Turku University Hospital, Turku, Finland
| | - Mikko Härmä
- Brain and Work Research Centre, Finnish Institute of Occupational Health, Helsinki, Finland
| | - Mikael Sallinen
- Brain and Work Research Centre, Finnish Institute of Occupational Health, Helsinki, Finland
- Agora Center, University of Jyväskylä, Jyväskylä, Finland
| | - Vesa M Olkkonen
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
- Institute of Biomedicine, Anatomy, University of Helsinki, Finland
| | - Harri Alenius
- Unit of Excellence for Immunotoxicology, Finnish Institute of Occupational Health, Helsinki, Finland
| | - Matti Jauhiainen
- Genomics and Biomarkers unit and Institute for Molecular Medicine FIMM, National Institute for Health and Welfare, Helsinki, Finland
| | - Tiina Paunio
- Genomics and Biomarkers unit and Institute for Molecular Medicine FIMM, National Institute for Health and Welfare, Helsinki, Finland
- Department of Psychiatry, University of Helsinki and Helsinki University Hospital, Finland
| | - Terho Lehtimäki
- Department of Clinical Chemistry, Fimlab Laboratories, and University of Tampere, School of Medicine, Tampere, Finland
| | - Veikko Salomaa
- Department of Chronic Disease Prevention, National Institute for Health and Welfare, Helsinki, Finland
| | - Matej Orešič
- VTT Technical Research Centre of Finland, Espoo, Finland
- Steno Diabetes Center A/S, Gentofte, Denmark
| | - Olli T Raitakari
- Research Centre of Applied and Preventive Cardiovascular Medicine, University of Turku, Turku, Finland
- Department of Clinical Physiology and Nuclear Medicine, Turku University Hospital, Turku, Finland
| | - Mika Ala-Korpela
- Computational Medicine, Institute of Health Sciences, University of Oulu, Oulu, Finland
- NMR Metabolomics Laboratory, School of Pharmacy, University of Eastern Finland, Kuopio, Finland
- Oulu University Hospital, Oulu, Finland
- Computational Medicine, School of Social and Community Medicine &Medical Research Council Integrative Epidemiology Unit, University of Bristol, Bristol, United Kingdom
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12
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Martinez NA, Ayala AM, Martinez M, Martinez-Rivera FJ, Miranda JD, Silva WI. Caveolin-1 Regulates the P2Y2 Receptor Signaling in Human 1321N1 Astrocytoma Cells. J Biol Chem 2016; 291:12208-22. [PMID: 27129210 DOI: 10.1074/jbc.m116.730226] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Indexed: 11/06/2022] Open
Abstract
Damage to the CNS can cause a differential spatio-temporal release of multiple factors, such as nucleotides, ATP and UTP. The latter interact with neuronal and glial nucleotide receptors. The P2Y2 nucleotide receptor (P2Y2R) has gained prominence as a modulator of gliotic responses after CNS injury. Still, the molecular mechanisms underlying these responses in glia are not fully understood. Membrane-raft microdomains, such as caveolae, and their constituent caveolins, modulate receptor signaling in astrocytes; yet, their role in P2Y2R signaling has not been adequately explored. Hence, this study evaluated the role of caveolin-1 (Cav-1) in modulating P2Y2R subcellular distribution and signaling in human 1321N1 astrocytoma cells. Recombinant hP2Y2R expressed in 1321N1 cells and Cav-1 were found to co-fractionate in light-density membrane-raft fractions, co-localize via confocal microscopy, and co-immunoprecipitate. Raft localization was dependent on ATP stimulation and Cav-1 expression. This hP2Y2R/Cav-1 distribution and interaction was confirmed with various cell model systems differing in the expression of both P2Y2R and Cav-1, and shRNA knockdown of Cav-1 expression. Furthermore, shRNA knockdown of Cav-1 expression decreased nucleotide-induced increases in the intracellular Ca(2+) concentration in 1321N1 and C6 glioma cells without altering TRAP-6 and carbachol Ca(2+) responses. In addition, Cav-1 shRNA knockdown also decreased AKT phosphorylation and altered the kinetics of ERK1/2 activation in 1321N1 cells. Our findings strongly suggest that P2Y2R interaction with Cav-1 in membrane-raft caveolae of 1321N1 cells modulates receptor coupling to its downstream signaling machinery. Thus, P2Y2R/Cav-1 interactions represent a novel target for controlling P2Y2R function after CNS injury.
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Affiliation(s)
| | | | | | - Freddyson J Martinez-Rivera
- Anatomy and Neurobiology, School of Medicine, University of Puerto Rico, Medical Sciences Campus, San Juan, Puerto Rico 00936
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13
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Meijer K, Vonk RJ, Priebe MG, Roelofsen H. Cell-based screening assay for anti-inflammatory activity of bioactive compounds. Food Chem 2014; 166:158-164. [PMID: 25053041 DOI: 10.1016/j.foodchem.2014.06.053] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 04/24/2014] [Accepted: 06/09/2014] [Indexed: 01/17/2023]
Abstract
Excess dietary intake may induce metabolic inflammation which is associated with insulin resistance and cardiovascular disease. Recent evidence indicates that dietary bioactive compounds may diminish metabolic inflammation. To identify anti-inflammatory bioactives, we developed a screening assay using the human H293-NF-κB-RE-luc2P reporter cell line. Under optimised conditions we determined the anti-inflammatory activity of vegetables and purified bioactives, by monitoring their potency to inhibit TNF-α-induced NF-κB activity, as assessed by sensitive chemiluminescence detection in a 96-well assay format. Minced broccoli seedlings reduced NF-κB activity by 16%, while sulphoraphane, the dominant bioactive in broccoli seedlings, inhibited NF-κB activity with an IC₅₀ of 5.11 μmol/l. Short-chain fatty acids also reduced NF-κB activity in the order butyrate>propionate≫acetate with IC₅₀ of 51, 223, and 1300 μmol/l, respectively. The H293-NF-κB-RE-luc2P reporter cell line is a sensitive tool for rapid high-throughput screening for bioactives with anti-inflammatory activity.
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Affiliation(s)
- Kees Meijer
- Center for Medical Biomics, University Medical Centre Groningen, Antonius Deusinglaan 1, 9713AV Groningen, The Netherlands.
| | - Roel J Vonk
- Center for Medical Biomics, University Medical Centre Groningen, Antonius Deusinglaan 1, 9713AV Groningen, The Netherlands
| | - Marion G Priebe
- Center for Medical Biomics, University Medical Centre Groningen, Antonius Deusinglaan 1, 9713AV Groningen, The Netherlands
| | - Han Roelofsen
- Center for Medical Biomics, University Medical Centre Groningen, Antonius Deusinglaan 1, 9713AV Groningen, The Netherlands
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14
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Gu HM, Wang FQ, Zhang DW. Caveolin-1 interacts with ATP binding cassette transporter G1 (ABCG1) and regulates ABCG1-mediated cholesterol efflux. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1841:847-58. [DOI: 10.1016/j.bbalip.2014.02.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 02/06/2014] [Accepted: 02/12/2014] [Indexed: 01/19/2023]
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15
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Lee HJ, Park HH, Kim JA, Park JH, Ryu J, Choi J, Lee J, Rhee WJ, Park TH. Enzyme delivery using the 30Kc19 protein and human serum albumin nanoparticles. Biomaterials 2014; 35:1696-704. [DOI: 10.1016/j.biomaterials.2013.11.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Accepted: 11/01/2013] [Indexed: 10/26/2022]
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16
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Chen YH, Lin WW, Liu CS, Hsu LS, Lin YM, Su SL. Caveolin-1 provides palliation for adverse hepatic reactions in hypercholesterolemic rabbits. PLoS One 2014; 9:e71862. [PMID: 24475013 PMCID: PMC3901645 DOI: 10.1371/journal.pone.0071862] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Accepted: 09/21/2013] [Indexed: 12/17/2022] Open
Abstract
Caveolins are an essential component of cholesterol-rich invaginations of the plasma membrane known as caveolae. These flask-shaped, invaginated structures participate in a number of important cellular processes, including vesicular transport, cholesterol homeostasis, and signal transduction. We investigated the effects of CAV-1 on mitochondrial biogenesis and antioxidant enzymes in hypercholesterolemia-affected target organs. A total of eighteen male New Zealand white rabbits were divided into three groups: a normal-diet group, an untreated hypercholesterolemia-induced group, and a hypercholesterolemia-induced group that received intravenous administration of antennapedia-CAV-1 (AP-CAV-1) peptide every 2 days for 2 weeks. Serum biochemistry, CAV-1 distribution, neutral lipid distribution, mitochondrial morphology, biogenesis-mediated protein content, oxidative stress balance, antioxidant enzyme levels, and apoptotic cell death of liver tissue were analysed. Hepatic and circulating cholesterol and low-density lipoprotein cholesterol (LDL-C) levels differed significantly between the three groups (P<0.05). Immunohistochemical staining intensity of CAV-1 was greater in AP-CAV-1-treated rabbits than in untreated rabbits, especially in the vicinity of the liver vasculature. The high levels of neutral lipids, malondialdehyde, peroxisome proliferator-activated receptor-γ coactive 1α (PGC-1α), and nuclear respiratory factor-1 (NRF-1) seen in untreated hypercholesteremic animals were attenuated by administration of AP-CAV-1 (P<0.05). In addition, mitochondria in animals that received treatment exhibited darker electron-dense matrix and integrated cristae. Furthermore, the levels of ROS modulator 1 (Romo1) and superoxide dismutase (SOD)-2, as well as catalase activity were significantly lower in CAV-1-treated hypercholesterolemic rabbits (P<0.05). AP-CAV-1 treatment also restored mitochondrial respiratory chain subunit protein content (OXPHOS complexes I–V), thereby preserving mitochondrial function (P<0.05). Furthermore, AP-CAV-1 treatment significantly suppressed apoptotic cell death, as evidenced by a reduction in the number of TUNEL-positive cells. Our results indirectly indicate that CAV-1 mediates the negative effects of PGC-1α on hepatic mitochondrial respiratory chain function, promotes the antioxidant enzyme defence system, and maintains mitochondrial biogenesis.
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Affiliation(s)
- Ya-Hui Chen
- Vascular and Genomic Center, Changhua Christian Hospital, Changhua, Taiwan
- Institute of Biochemistry and Biotechnology, Chung Shan Medical University, Taichung, Taiwan
| | - Wei-Wen Lin
- Division of Cardiovascular Center, Department of Internal Medicine, Taichung Veterans General Hospital, Taichung, Taiwan
| | - Chin-San Liu
- Vascular and Genomic Center, Changhua Christian Hospital, Changhua, Taiwan
- Graduate Institute of Integrative Medicine, China Medical University, Taichung, Taiwan
| | - Li-Sung Hsu
- Institute of Biochemistry and Biotechnology, Chung Shan Medical University, Taichung, Taiwan
| | - Yueh-Min Lin
- Department of Pathology, Changhua Christian Hospital, Changhua, Taiwan
- Department of Medical Technology, Jen-Teh Junior College of Medicine, Nursing and Management, Miaoli, Taiwan
| | - Shih-Li Su
- Vascular and Genomic Center, Changhua Christian Hospital, Changhua, Taiwan
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Changhua Christian Hospital, Changhua, Taiwan
- Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan
- * E-mail:
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17
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Davey AE, Leach K, Valant C, Conigrave AD, Sexton PM, Christopoulos A. Positive and negative allosteric modulators promote biased signaling at the calcium-sensing receptor. Endocrinology 2012; 153:1232-41. [PMID: 22210744 DOI: 10.1210/en.2011-1426] [Citation(s) in RCA: 123] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The calcium-sensing receptor (CaSR) is a G protein-coupled receptor whose function can be allosterically modulated in a positive or negative manner by calcimimetics or calcilytics, respectively. Indeed, the second-generation calcimimetic, cinacalcet, has proven clinically useful in the treatment of chronic kidney disease patients with secondary hyperparathyroidism but is not widely used in earlier stages of renal disease due to the potential to predispose such patients to hypocalcaemia and hyperphosphatemia. The development of a biased CaSR ligand that is more selective for specific signaling pathway(s) leading only to beneficial effects may overcome this limitation. The detection of such stimulus-bias at a G protein-coupled receptor requires investigation across multiple signaling pathways and the development of methods to quantify the effects of allosteric ligands on orthosteric ligand affinity and cooperativity at each pathway. In the current study, we determined the effects of the calcimimetics, NPS-R568 or cinacalcet, and the calcilytic, NPS-2143, on Ca(o)(2+)-mediated intracellular Ca(2+) mobilization, ERK1/2 phosphorylation, and plasma membrane ruffling in a stably transfected human embryonic kidney 293-TREx c-myc-CaSR cell line and applied a novel analytical model to quantify these modulator effects. We present quantitative evidence for the generation of stimulus bias by both positive and negative allosteric modulators of the CaSR, manifested as greater allosteric modulation of intracellular Ca(2+) mobilization relative to ERK1/2 phosphorylation, and a higher affinity of the modulators for the state of the CaSR mediating plasma membrane ruffling relative to the other two pathways. Our findings provide the first evidence that an allosteric modulator used in clinical practice exhibits stimulus bias.
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Affiliation(s)
- Anna E Davey
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia
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18
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Lemaire-Ewing S, Lagrost L, Néel D. Lipid rafts: a signalling platform linking lipoprotein metabolism to atherogenesis. Atherosclerosis 2011; 221:303-10. [PMID: 22071358 DOI: 10.1016/j.atherosclerosis.2011.10.016] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Revised: 09/22/2011] [Accepted: 10/12/2011] [Indexed: 01/16/2023]
Abstract
Lipid rafts are microdomains of the plasma membrane which are enriched in cholesterol and sphingolipids. They serve as a platform for signal transduction, in particular during immune and inflammatory responses. As hypercholesterolemia and inflammation are two key elements of atherogenesis, it is conceivable that the cholesterol and cholesterol oxide content of lipid rafts might influence the inflammatory signalling pathways, thus modulating the development of atherosclerosis. In support of this emerging view, lipid rafts have been shown to be involved in several key steps of atherogenesis, such as the oxysterol-mediated apoptosis of vascular cells, the blunted ability of high density lipoproteins (HDL) to exert anti-inflammatory effects, and the exacerbated secretion of pro-inflammatory cytokines by immune cells. Additional studies are now required to address the relative contribution of lipid raft abnormalities to the pathophysiology of atherosclerosis and cardiovascular disease.
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19
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Le Lay S, Rodriguez M, Jessup W, Rentero C, Li Q, Cartland S, Grewal T, Gaus K. Caveolin-1-mediated apolipoprotein A-I membrane binding sites are not required for cholesterol efflux. PLoS One 2011; 6:e23353. [PMID: 21858084 PMCID: PMC3155548 DOI: 10.1371/journal.pone.0023353] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Accepted: 07/13/2011] [Indexed: 11/18/2022] Open
Abstract
Caveolin-1 (Cav1), a structural protein required for the formation of invaginated membrane domains known as caveolae, has been implicated in cholesterol trafficking and homeostasis. Here we investigated the contribution of Cav1 to apolipoprotein A-I (apoA-I) cell surface binding and intracellular processing using mouse embryonic fibroblasts (MEFs) derived from wild type (WT) or Cav1-deficient (Cav1(-/-)) animals. We found that cells expressing Cav1 have 2.6-fold more apoA-I binding sites than Cav1(-/-) cells although these additional binding sites are not associated with detergent-free lipid rafts. Further, Cav1-mediated binding targets apoA-I for internalization and degradation and these processes are not correlated to cholesterol efflux. Despite lower apoA-I binding, cholesterol efflux from Cav1(-/-) MEFs is 1.7-fold higher than from WT MEFs. Stimulation of ABCA1 expression with an LXR agonist enhances cholesterol efflux from both WT and Cav1(-/-) cells without increasing apoA-I surface binding or affecting apoA-I processing. Our results indicate that there are at least two independent lipid binding sites for apoA-I; Cav1-mediated apoA-I surface binding and uptake is not linked to cholesterol efflux, indicating that membrane domains other than caveolae regulate ABCA1-mediated cholesterol efflux.
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Affiliation(s)
- Soazig Le Lay
- Centre de Recherche des Cordeliers, INSERM, U872, Paris, France
| | - Macarena Rodriguez
- Centre for Vascular Research, University of New South Wales, Sydney, Australia
| | - Wendy Jessup
- Centre for Vascular Research, University of New South Wales, Sydney, Australia
| | - Carles Rentero
- Centre for Vascular Research, University of New South Wales, Sydney, Australia
| | - Qiong Li
- Centre for Vascular Research, University of New South Wales, Sydney, Australia
| | - Siân Cartland
- Centre for Vascular Research, University of New South Wales, Sydney, Australia
| | - Thomas Grewal
- Faculty of Pharmacy, University of Sydney, Sydney, Australia
| | - Katharina Gaus
- Centre for Vascular Research, University of New South Wales, Sydney, Australia
- * E-mail:
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20
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Kent AP, Stylianou IM. Scavenger receptor class B member 1 protein: hepatic regulation and its effects on lipids, reverse cholesterol transport, and atherosclerosis. Hepat Med 2011; 3:29-44. [PMID: 24367219 PMCID: PMC3846864 DOI: 10.2147/hmer.s7860] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Scavenger receptor class B member 1 (SR-BI, also known as SCARB1) is the primary receptor for the selective uptake of cholesterol from high-density lipoprotein (HDL). SR-BI is present in several key tissues; however, its presence and function in the liver is deemed the most relevant for protection against atherosclerosis. Cholesterol is transferred from HDL via SR-BI to the liver, which ultimately results in the excretion of cholesterol via bile and feces in what is known as the reverse cholesterol transport pathway. Much of our knowledge of SR-BI hepatic function and regulation is derived from mouse models and in vitro characterization. Multiple independent regulatory mechanisms of SR-BI have been discovered that operate at the transcriptional and post-transcriptional levels. In this review we summarize the critical discoveries relating to hepatic SR-BI cholesterol metabolism, atherosclerosis, and regulation of SR-BI, as well as alternative functions that may indirectly affect atherosclerosis.
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Affiliation(s)
- Anthony P Kent
- Department of Medicine and Institute for Translational Medicine and Therapeutics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - Ioannis M Stylianou
- Department of Medicine and Institute for Translational Medicine and Therapeutics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
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21
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Flotillin-1 is essential for PKC-triggered endocytosis and membrane microdomain localization of DAT. Nat Neurosci 2011; 14:469-77. [PMID: 21399631 PMCID: PMC3066276 DOI: 10.1038/nn.2781] [Citation(s) in RCA: 147] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Accepted: 02/18/2011] [Indexed: 01/26/2023]
Abstract
Plasmalemmal neurotransmitter transporters (NTTs) regulate the level of neurotransmitters, such as dopamine (DA) and glutamate, after their release at brain synapses. Stimuli including protein kinase C (PKC) activation can lead to the internalization of some NTTs and a reduction in neurotransmitter clearance capacity. We found that the protein Flotillin-1 (Flot1), also known as Reggie-2, was required for PKC-regulated internalization of members of two different NTT families, the DA transporter (DAT) and the glial glutamate transporter EAAT2, and we identified a conserved serine residue in Flot1 that is essential for transporter internalization. Further analysis revealed that Flot1 was also required to localize DAT within plasma membrane microdomains in stable cell lines, and was essential for amphetamine-induced reverse transport of DA in neurons but not for DA uptake. In sum, our findings provide evidence for a critical role of Flot1-enriched membrane microdomains in PKC-triggered DAT endocytosis and the actions of amphetamine.
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22
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Truong TQ, Aubin D, Falstrault L, Brodeur MR, Brissette L. SR-BI, CD36, and caveolin-1 contribute positively to cholesterol efflux in hepatic cells. Cell Biochem Funct 2010; 28:480-9. [DOI: 10.1002/cbf.1680] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Cellular cholesterol delivery, intracellular processing and utilization for biosynthesis of steroid hormones. Nutr Metab (Lond) 2010; 7:47. [PMID: 20515451 PMCID: PMC2890697 DOI: 10.1186/1743-7075-7-47] [Citation(s) in RCA: 286] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Accepted: 06/01/2010] [Indexed: 11/28/2022] Open
Abstract
Steroid hormones regulate diverse physiological functions such as reproduction, blood salt balance, maintenance of secondary sexual characteristics, response to stress, neuronal function and various metabolic processes. They are synthesized from cholesterol mainly in the adrenal gland and gonads in response to tissue-specific tropic hormones. These steroidogenic tissues are unique in that they require cholesterol not only for membrane biogenesis, maintenance of membrane fluidity and cell signaling, but also as the starting material for the biosynthesis of steroid hormones. It is not surprising, then, that cells of steroidogenic tissues have evolved with multiple pathways to assure the constant supply of cholesterol needed to maintain optimum steroid synthesis. The cholesterol utilized for steroidogenesis is derived from a combination of sources: 1) de novo synthesis in the endoplasmic reticulum (ER); 2) the mobilization of cholesteryl esters (CEs) stored in lipid droplets through cholesteryl ester hydrolase; 3) plasma lipoprotein-derived CEs obtained by either LDL receptor-mediated endocytic and/or SR-BI-mediated selective uptake; and 4) in some cultured cell systems from plasma membrane-associated free cholesterol. Here, we focus on recent insights into the molecules and cellular processes that mediate the uptake of plasma lipoprotein-derived cholesterol, events connected with the intracellular cholesterol processing and the role of crucial proteins that mediate cholesterol transport to mitochondria for its utilization for steroid hormone production. In particular, we discuss the structure and function of SR-BI, the importance of the selective cholesterol transport pathway in providing cholesterol substrate for steroid biosynthesis and the role of two key proteins, StAR and PBR/TSO in facilitating cholesterol delivery to inner mitochondrial membrane sites, where P450scc (CYP11A) is localized and where the conversion of cholesterol to pregnenolone (the common steroid precursor) takes place.
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Fujimoto VY, Kane JP, Ishida BY, Bloom MS, Browne RW. High-density lipoprotein metabolism and the human embryo. Hum Reprod Update 2010; 16:20-38. [PMID: 19700490 DOI: 10.1093/humupd/dmp029] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND High-density lipoprotein (HDL) appears to be the dominant lipoprotein particle in human follicular fluid (FF). The reported anti-atherogenic properties of HDL have been attributed in part to reverse cholesterol transport. The discoveries of the scavenger receptor class B type I (SR-BI) and the ATP-binding cassette A1 lipid (ABCA1) transporter have generated studies aimed at unraveling the pathways of HDL biogenesis, remodeling and catabolism. The production of SR-BI and ABCA1 knockout mice as well as other lipoprotein metabolism-associated mutants has resulted in reduced or absent fertility, leading us to postulate the existence of a human hepatic-ovarian HDL-associated axis of fertility. Here, we review an evolving literature on the role of HDL metabolism on mammalian fertility and oocyte development. METHODS An extensive online search was conducted of published articles relevant to the section topics discussed. All relevant English language articles contained in Pubmed/Medline, with no specific time frame for publication, were considered for this narrative review. Cardiovascular literature was highly cited due to the wealth of relevant knowledge on HDL metabolism, and the dearth thereof in the reproductive field. RESULTS Various vertebrate models demonstrate a role for HDL in embryo development and fertility. In our clinical studies, FF levels of HDL cholesterol and apolipoprotein AI levels were negatively associated with embryo fragmentation, but not with embryo cell cleavage rate. However, the HDL component, paraoxonase 1 arylesterase activity, was positively associated with embryo cell cleavage rate. CONCLUSIONS HDL contributes to intra-follicular cholesterol homeostasis which appears to be important for successful oocyte and embryo development.
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Affiliation(s)
- Victor Y Fujimoto
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of California at San Francisco, San Francisco, CA 94115-0916, USA.
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Truong TQ, Brodeur MR, Falstrault L, Rhainds D, Brissette L. Expression of caveolin-1 in hepatic cells increases oxidized LDL uptake and preserves the expression of lipoprotein receptors. J Cell Biochem 2009; 108:906-15. [DOI: 10.1002/jcb.22321] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Frank PG, Pavlides S, Cheung MWC, Daumer K, Lisanti MP. Role of caveolin-1 in the regulation of lipoprotein metabolism. Am J Physiol Cell Physiol 2008; 295:C242-8. [PMID: 18508910 DOI: 10.1152/ajpcell.00185.2008] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Lipoprotein metabolism plays an important role in the development of several human diseases, including coronary artery disease and the metabolic syndrome. A good comprehension of the factors that regulate the metabolism of the various lipoproteins is therefore key to better understanding the variables associated with the development of these diseases. Among the players identified are regulators such as caveolins and caveolae. Caveolae are small plasma membrane invaginations that are observed in terminally differentiated cells. Their most important protein marker, caveolin-1, has been shown to play a key role in the regulation of several cellular signaling pathways and in the regulation of plasma lipoprotein metabolism. In the present paper, we have examined the role of caveolin-1 in lipoprotein metabolism using caveolin-1-deficient (Cav-1(-/-)) mice. Our data show that, while Cav-1(-/-) mice show increased plasma triglyceride levels, they also display reduced hepatic very low-density lipoprotein (VLDL) secretion. Additionally, we also found that a caveolin-1 deficiency is associated with an increase in high-density lipoprotein (HDL), and these HDL particles are enriched in cholesteryl ester in Cav-1(-/-) mice when compared with HDL obtained from wild-type mice. Finally, our data suggest that a caveolin-1 deficiency prevents the transcytosis of LDL across endothelial cells, and therefore, that caveolin-1 may be implicated in the regulation of plasma LDL levels. Taken together, our studies suggest that caveolin-1 plays an important role in the regulation of lipoprotein metabolism by controlling their plasma levels as well as their lipid composition. Thus caveolin-1 may also play an important role in the development of atherosclerosis.
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Affiliation(s)
- Philippe G Frank
- Kimmel Cancer Center, Department of Cancer Biology, and Biochemistry and Molecular Biology, and Stem Cell Biology and Regenerative Medicine Center, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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Sengupta P, Philip F, Scarlata S. Caveolin-1 alters Ca(2+) signal duration through specific interaction with the G alpha q family of G proteins. J Cell Sci 2008; 121:1363-72. [PMID: 18397999 PMCID: PMC2639659 DOI: 10.1242/jcs.020081] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Caveolae are membrane domains having caveolin-1 (Cav1) as their main structural component. Here, we determined whether Cav1 affects Ca(2+) signaling through the Galpha(q)-phospholipase-Cbeta (PLCbeta) pathway using Fischer rat thyroid cells that lack Cav1 (FRTcav(-)) and a sister line that forms caveolae-like domains due to stable transfection with Cav1 (FRTcav(+)). In the resting state, we found that eCFP-Gbetagamma and Galpha(q)-eYFP are similarly associated in both cell lines by Forster resonance energy transfer (FRET). Upon stimulation, the amount of FRET between Galpha(q)-eYFP and eCFP-Gbetagamma remains high in FRTcav(-) cells, but decreases almost completely in FRTcav(+) cells, suggesting that Cav1 is increasing the separation between Galpha(q)-Gbetagamma subunits. In FRTcav(-) cells overexpressing PLCbeta, a rapid recovery of Ca(2+) is observed after stimulation. However, FRTcav(+) cells show a sustained level of elevated Ca(2+). FRET and colocalization show specific interactions between Galpha(q) and Cav1 that increase upon stimulation. Fluorescence correlation spectroscopy studies show that the mobility of Galpha(q)-eGFP is unaffected by activation in either cell type. The mobility of eGFP-Gbetagamma remains slow in FRTcav(-) cells but increases in FRTcav(+) cells. Together, our data suggest that, upon stimulation, Galpha(q)(GTP) switches from having strong interactions with Gbetagamma to Cav1, thereby releasing Gbetagamma. This prolongs the recombination time for the heterotrimer, thus causing a sustained Ca(2+) signal.
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Affiliation(s)
- Parijat Sengupta
- Department of Physiology and Biophysics, BST6-145, Stony Brook University, Stony Brook, NY 11794-8661, USA
| | | | - Suzanne Scarlata
- Department of Physiology and Biophysics, BST6-145, Stony Brook University, Stony Brook, NY 11794-8661, USA
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Cha SK, Wu T, Huang CL. Protein kinase C inhibits caveolae-mediated endocytosis of TRPV5. Am J Physiol Renal Physiol 2008; 294:F1212-21. [PMID: 18305097 DOI: 10.1152/ajprenal.00007.2008] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Transient receptor potential vanilloid 5 (TRPV5) constitutes the apical entry pathway for transepithelial Ca2+reabsorption in kidney. Many hormones alter renal Ca2+reabsorption at least partly by regulating TRPV5. The mechanism for acute regulation of TRPV5 by phospholipase C-coupled hormones is largely unknown. Here, we found that protein kinase C (PKC) activator 1-oleoyl-acetyl-sn-glycerol (OAG) increased TRPV5 current density and surface abundance in cultured cells. The OAG-mediated increase of TRPV5 was prevented by preincubation with specific PKC inhibitors. Coexpression with a dominant-negative dynamin increased the basal TRPV5 current density and prevented the increase by OAG. Knockdown of caveolin-1 by small interference RNA (siRNA) prevented the increase of TRPV5 by OAG. In contrast, knockdown of clathrin heavy chain had no effects. OAG had no effect on TRPV5 expressed in caveolin-1 null cells derived from caveolin-1 knockout mice. Forced expression of recombinant caveolin-1 restored the regulation of TRPV5 by OAG in caveolin-1 knockout cells. Mutations of serine-299 and/or serine-654 of TRPV5 (consensus residues for phosphorylation by PKC) abolished the regulation by OAG. Parathyroid hormone (PTH) increased TRPV5 current density in cells coexpressing TRPV5 and type 1 PTH receptor. The increase caused by PTH was prevented by PKC inhibitor, mutation of serine-299/serine-654, or by knockdown of caveolin-1. Thus, TRPV5 undergoes constitutive caveolae-mediated endocytosis. Activation of PKC increases cell surface abundance of TRPV5 by inhibiting the endocytosis. This mechanism of regulation by PKC may contribute to the acute stimulation of TRPV5 and renal Ca2+reabsorption by PTH.
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Wang X, Mu H, Chai H, Liao D, Yao Q, Chen C. Human immunodeficiency virus protease inhibitor ritonavir inhibits cholesterol efflux from human macrophage-derived foam cells. THE AMERICAN JOURNAL OF PATHOLOGY 2007; 171:304-14. [PMID: 17591975 PMCID: PMC1941585 DOI: 10.2353/ajpath.2007.060965] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Clinical use of human immunodeficiency virus protease inhibitors such as ritonavir may be associated with cardiovascular disease. The objective of this study was to determine the effects and molecular mechanisms of ritonavir on cholesterol efflux from human macrophage-derived foam cells, which is a critical factor of atherogenesis. Human THP-1 monocytes and peripheral blood mononuclear cells were preincubated with acetylated low-density lipoprotein and [(3)H]cholesterol to form foam cells, which were then treated with apolipoprotein A-I for cholesterol efflux assay. A clinically relevant concentration of ritonavir (15 mumol/L) significantly reduced cholesterol efflux from THP-1 and peripheral blood mononuclear cells to apolipoprotein A-I by 30 and 29%, respectively, as compared with controls. In addition, ritonavir significantly decreased the expression of scavenger receptor B1 and caveolin-1, whereas it significantly increased superoxide anion production and activated extracellular signal-regulated kinase (ERK) 1/2 in macrophages. Mitochondrial membrane potential was significantly reduced, whereas NADPH oxidase subunits were increased in ritonavir-treated macrophages. Consequently, the antioxidant seleno-l-methionine, the specific ERK1/2 inhibitor PD98059, or infection of a recombinant adenovirus encoding the dominant-negative form of ERK2 effectively blocked ritonavir-induced decrease of cholesterol efflux. Therefore, human immunodeficiency virus protease inhibitor ritonavir significantly inhibits cholesterol efflux from macrophages, which may be mediated by mitochondrial dysfunction, oxidative stress, ERK1/2 activation, and down-regulation of scavenger receptor B1 and caveolin-1.
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Affiliation(s)
- Xinwen Wang
- Michael E DeBakey, Department of Surgery, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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Orlowski S, Coméra C, Tercé F, Collet X. Lipid rafts: dream or reality for cholesterol transporters? EUROPEAN BIOPHYSICS JOURNAL: EBJ 2007; 36:869-85. [PMID: 17576551 DOI: 10.1007/s00249-007-0193-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2007] [Revised: 05/11/2007] [Accepted: 05/15/2007] [Indexed: 01/12/2023]
Abstract
As a key constituent of the cell membranes, cholesterol is an endogenous component of mammalian cells of primary importance, and is thus subjected to highly regulated homeostasis at the cellular level as well as at the level of the whole body. This regulation requires adapted mechanisms favoring the handling of cholesterol in aqueous compartments, as well as its transfer into or out of membranes, involving membrane proteins. A membrane exhibits functional properties largely depending on its lipid composition and on its structural organization, which very often involves cholesterol-rich microdomains. Then there is the appealing possibility that cholesterol may regulate its own transmembrane transport at a purely functional level, independently of any transcriptional regulation based on cholesterol-sensitive nuclear factors controling the expression level of lipid transport proteins. Indeed, the main cholesterol "transporters" presently believed to mediate for instance the intestinal absorption of cholesterol, that are SR-BI, NPC1L1, ABCA1, ABCG1, ABCG5/G8 and even P-glycoprotein, all present privileged functional relationships with membrane cholesterol-containing microdomains. In particular, they all more or less clearly induce membrane disorganization, supposed to facilitate cholesterol exchanges with the close aqueous medium. The actual lipid substrates handled by these transporters are not yet unambiguously determined, but they likely concern the components of membrane microdomains. Conversely, raft alterations may provide specific modulations of the transporter activities, as well as they can induce indirect effects via local perturbations of the membrane. Finally, these cholesterol transporters undergo regulated intracellular trafficking, with presumably some relationships to rafts which remain to be clarified.
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Affiliation(s)
- Stéphane Orlowski
- SB2SM/IBTS and URA 2096 CNRS, CEA, Centre de Saclay, 91191, Gif-sur-Yvette cedex, France.
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Schroeder F, Atshaves BP, McIntosh AL, Gallegos AM, Storey SM, Parr RD, Jefferson JR, Ball JM, Kier AB. Sterol carrier protein-2: new roles in regulating lipid rafts and signaling. BIOCHIMICA ET BIOPHYSICA ACTA 2007; 1771:700-18. [PMID: 17543577 PMCID: PMC1989133 DOI: 10.1016/j.bbalip.2007.04.005] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2006] [Revised: 03/28/2007] [Accepted: 04/03/2007] [Indexed: 12/31/2022]
Abstract
Sterol carrier protein-2 (SCP-2) was independently discovered as a soluble protein that binds and transfers cholesterol as well as phospholipids (nonspecific lipid transfer protein, nsLTP) in vitro. Physiological functions of this protein are only now beginning to be resolved. The gene encoding SCP-2 also encodes sterol carrier protein-x (SCP-x) arising from an alternate transcription site. In vitro and in vivo SCP-x serves as a peroxisomal 3-ketoacyl-CoA thiolase in oxidation of branched-chain lipids (cholesterol to form bile acids; branched-chain fatty acid for detoxification). While peroxisomal SCP-2 facilitates branched-chain lipid oxidation, the role(s) of extraperoxisomal (up to 50% of total) are less clear. Studies using transfected fibroblasts overexpressing SCP-2 and hepatocytes from SCP-2/SCP-x gene-ablated mice reveal that SCP-2 selectively remodels the lipid composition, structure, and function of lipid rafts/caveolae. Studies of purified SCP-2 and in cells show that SCP-2 has high affinity for and selectively transfers many lipid species involved in intracellular signaling: fatty acids, fatty acyl CoAs, lysophosphatidic acid, phosphatidylinositols, and sphingolipids (sphingomyelin, ceramide, mono-di-and multi-hexosylceramides, gangliosides). SCP-2 selectively redistributes these signaling lipids between lipid rafts/caveolae and intracellular sites. These findings suggest SCP-2 serves not only in cholesterol and phospholipid transfer, but also in regulating multiple lipid signaling pathways in lipid raft/caveolae microdomains of the plasma membrane.
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Affiliation(s)
- Friedhelm Schroeder
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843-4466, USA.
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Labonté ED, Howles PN, Granholm NA, Rojas JC, Davies JP, Ioannou YA, Hui DY. Class B type I scavenger receptor is responsible for the high affinity cholesterol binding activity of intestinal brush border membrane vesicles. Biochim Biophys Acta Mol Cell Biol Lipids 2007; 1771:1132-9. [PMID: 17442616 PMCID: PMC2071925 DOI: 10.1016/j.bbalip.2007.03.002] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Revised: 03/05/2007] [Accepted: 03/06/2007] [Indexed: 11/30/2022]
Abstract
Recent studies have documented the importance of Niemann-Pick C1-like 1 protein (NPC1L1), a putative physiological target of the drug ezetimibe, in mediating intestinal cholesterol absorption. However, whether NPC1L1 is the high affinity cholesterol binding protein on intestinal brush border membranes is still controversial. In this study, brush border membrane vesicles (BBMV) from wild type and NPC1L1-/- mice were isolated and assayed for micellar cholesterol binding in the presence or absence of ezetimibe. Results confirmed the loss of the high affinity component of cholesterol binding when wild type BBMV preparations were incubated with antiserum against the class B type 1 scavenger receptor (SR-BI) in the reaction mixture similar to previous studies. Subsequently, second order binding of cholesterol was observed with BBMV from wild type and NPC1L1-/- mice. The inclusion of ezetimibe in these in vitro reaction assays resulted in the loss of the high affinity component of cholesterol interaction. Surprisingly, BBMVs from NPC1L1-/- mice maintained active binding of cholesterol. These results documented that SR-BI, not NPC1L1, is the major protein responsible for the initial high affinity cholesterol ligand binding process in the cholesterol absorption pathway. Additionally, ezetimibe may inhibit BBM cholesterol binding through targets such as SR-BI in addition to its inhibition of NPC1L1.
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Affiliation(s)
- Eric D. Labonté
- Department of Pathology, Genome Research Institute, University of Cincinnati, Cincinnati, Ohio
| | - Philip N. Howles
- Department of Pathology, Genome Research Institute, University of Cincinnati, Cincinnati, Ohio
| | - Norman A. Granholm
- Department of Pathology, Genome Research Institute, University of Cincinnati, Cincinnati, Ohio
| | - Juan C. Rojas
- Department of Pathology, Genome Research Institute, University of Cincinnati, Cincinnati, Ohio
| | - Joanna P. Davies
- Department of Human Genetics, The Mount Sinai School of Medicine, New York, New York
| | - Yiannis A. Ioannou
- Department of Human Genetics, The Mount Sinai School of Medicine, New York, New York
| | - David Y. Hui
- Department of Pathology, Genome Research Institute, University of Cincinnati, Cincinnati, Ohio
- Correspondence to: David Y. Hui, Ph.D., Department of Pathology (ML0507), Genome Research Institute, University of Cincinnati, 2120 E. Galbraith Rd., Cincinnati, OH 45237. Ph: 513-338-9152; FAX: 513-558-1312; E-mail:
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Lutgens SPM, Kisters N, Lutgens E, van Haaften RIM, Evelo CTA, de Winther MPJ, Saftig P, Daemen MJAP, Heeneman S, Cleutjens KBJM. Gene profiling of cathepsin K deficiency in atherogenesis: profibrotic but lipogenic. J Pathol 2006; 210:334-43. [PMID: 16972305 DOI: 10.1002/path.2054] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Recently, we showed that cathepsin K deficiency reduces atherosclerotic plaque progression, induces plaque fibrosis, but aggravates macrophage foam cell formation in the ApoE -/- mouse. To obtain more insight into the molecular mechanisms by which cathepsin K disruption evokes the observed phenotypic changes, we used microarray analysis for gene expression profiling of aortic arches of CatK -/-/ApoE -/- and ApoE -/- mice on a mouse oligo microarray. Out of 20 280 reporters, 444 were significantly differentially expressed (p-value of < 0.05, fold change of > or = 1.4 or < or = - 1.4, and intensity value of > 2.5 times background in at least one channel). Ingenuity Pathway Analysis and GenMAPP revealed upregulation of genes involved in lipid uptake, trafficking, and intracellular storage, including caveolin - 1, - 2, - 3 and CD36, and profibrotic genes involved in transforming growth factor beta (TGFbeta) signalling, including TGFbeta2, latent TGFbeta binding protein-1 (LTBP1), and secreted protein, acidic and rich in cysteine (SPARC), in CatK -/-/ApoE -/- mice. Differential gene expression was confirmed at the mRNA and protein levels. In vitro modified low density lipoprotein (LDL) uptake assays, using bone marrow derived macrophages preincubated with caveolae and scavenger receptor inhibitors, confirmed the importance of caveolins and CD36 in increasing modified LDL uptake in the absence of cathepsin K. In conclusion, we suggest that cathepsin K deficiency alters plaque phenotype not only by decreasing proteolytic activity, but also by stimulating TGFbeta signalling. Besides this profibrotic effect, cathepsin K deficiency has a lipogenic effect owing to increased lipid uptake mediated by CD36 and caveolins.
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Affiliation(s)
- S P M Lutgens
- Departments of Pathology, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, P. Debyelaan 25, Maastricht, The Netherlands
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Yu Z, Beer C, Koester M, Wirth M. Caveolin-1 interacts with the Gag precursor of murine leukaemia virus and modulates virus production. Virol J 2006; 3:73. [PMID: 16956408 PMCID: PMC1570462 DOI: 10.1186/1743-422x-3-73] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2006] [Accepted: 09/06/2006] [Indexed: 11/23/2022] Open
Abstract
Background Retroviral Gag determines virus assembly at the plasma membrane and the formation of virus-like particles in intracellular multivesicular bodies. Thereby, retroviruses exploit by interaction with cellular partners the cellular machineries for vesicular transport in various ways. Results The retroviral Gag precursor protein drives assembly of murine leukaemia viruses (MLV) at the plasma membrane (PM) and the formation of virus like particles in multivesicular bodies (MVBs). In our study we show that caveolin-1 (Cav-1), a multifunctional membrane-associated protein, co-localizes with Gag in a punctate pattern at the PM of infected NIH 3T3 cells. We provide evidence that Cav-1 interacts with the matrix protein (MA) of the Gag precursor. This interaction is mediated by a Cav-1 binding domain (CBD) within the N-terminus of MA. Interestingly, the CBD motif identified within MA is highly conserved among most other γ-retroviruses. Furthermore, Cav-1 is incorporated into MLV released from NIH 3T3 cells. Overexpression of a GFP fusion protein containing the putative CBD of the retroviral MA resulted in a considerable decrease in production of infectious retrovirus. Moreover, expression of a dominant-negative Cav-1 mutant affected retroviral titres significantly. Conclusion This study demonstrates that Cav-1 interacts with MLV Gag, co-localizes with Gag at the PM and affects the production of infectious virus. The results strongly suggest a role for Cav-1 in the process of virus assembly.
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Affiliation(s)
- Zheng Yu
- Molecular Biotechnology Division, German Research Centre for Biotechnology, GBF, Mascheroder Weg 1, Braunschweig, Germany
| | - Christiane Beer
- Molecular Biotechnology Division, German Research Centre for Biotechnology, GBF, Mascheroder Weg 1, Braunschweig, Germany
- Department of Molecular Biology, Aarhus University, C.F. Mollers Alle 130, Aarhus, Denmark
| | - Mario Koester
- Molecular Biotechnology Division, German Research Centre for Biotechnology, GBF, Mascheroder Weg 1, Braunschweig, Germany
| | - Manfred Wirth
- Molecular Biotechnology Division, German Research Centre for Biotechnology, GBF, Mascheroder Weg 1, Braunschweig, Germany
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Jessup W, Gelissen IC, Gaus K, Kritharides L. Roles of ATP binding cassette transporters A1 and G1, scavenger receptor BI and membrane lipid domains in cholesterol export from macrophages. Curr Opin Lipidol 2006; 17:247-57. [PMID: 16680029 DOI: 10.1097/01.mol.0000226116.35555.eb] [Citation(s) in RCA: 203] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW The initial steps of reverse cholesterol transport involve export of cholesterol from peripheral cells to plasma lipoproteins for subsequent delivery to the liver. The review discusses recent developments in our understanding of how these steps occur, with particular emphasis on the macrophage, the major site of cellular cholesterol accumulation in atherosclerosis. RECENT FINDINGS ATP binding cassette transporter (ABC) A1 exports cholesterol and phospholipid to lipid-free apolipoproteins, while ATP binding cassette transporter G1 and scavenger receptor BI export cholesterol to phospholipid-containing acceptors. ABCA1-dependent cholesterol export involves an initial interaction of apolipoprotein AI with lipid raft membrane domains, although ABCA1 and most exported cholesterol are not raft associated. ABCG1 exports cholesterol to HDL and other phospholipid-containing acceptors. These include particles generated during lipidation of apoAI by ABCA1, suggesting that the two transporters cooperate in cholesterol export. Scavenger receptor BI is atheroprotective, mediating clearance of HDL cholesterol by the liver. The relative contributions of scavenger receptor BI and ABCG to cholesterol export to HDL from macrophages is unclear and may depend on cellular cholesterol status and the cholesterol gradient between cell and acceptor. SUMMARY The presence of distinct pathways for cholesterol efflux to lipid-free apolipoprotein AI and phospholipid-containing HDL species clarifies our understanding of reverse cholesterol transport, and provides new opportunities for its therapeutic manipulation.
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Affiliation(s)
- Wendy Jessup
- Centre for Vascular Research, at the School of Medical Sciences, University of New South Wales, Sydney, Australia.
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Frank PG, Cheung MWC, Pavlides S, Llaverias G, Park DS, Lisanti MP. Caveolin-1 and regulation of cellular cholesterol homeostasis. Am J Physiol Heart Circ Physiol 2006; 291:H677-86. [PMID: 16603689 DOI: 10.1152/ajpheart.01092.2005] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Caveolae are 50- to 100-nm cell surface plasma membrane invaginations present in terminally differentiated cells. They are characterized by the presence of caveolin-1, sphingolipids, and cholesterol. Caveolin-1 is thought to play an important role in the regulation of cellular cholesterol homeostasis, a process that needs to be properly controlled to limit and prevent cholesterol accumulation and eventually atherosclerosis. We have recently generated caveolin-1-deficient [Cav-1(-/-)] mice in which caveolae organelles are completely eliminated from all cell types, except cardiac and skeletal muscle. In the present study, we examined the metabolism of cholesterol in wild-type (WT) and Cav-1(-/-) mouse embryonic fibroblasts (MEFs) and mouse peritoneal macrophages (MPMs). We observed that Cav-1(-/-) MEFs are enriched in esterified cholesterol but depleted of free cholesterol compared with their wild-type counterparts. Similarly, Cav-1(-/-) MPMs also contained less free cholesterol and were enriched in esterified cholesterol on cholesterol loading. In agreement with this finding, caveolin-1 deficiency was associated with reduced free cholesterol synthesis but increased acyl-CoA:cholesterol acyl-transferase (ACAT) activity. In wild-type MPMs, we observed that caveolin-1 was markedly upregulated on cholesterol loading. Despite these differences, cellular cholesterol efflux from MEFs and MPMs to HDL was not affected in the Cav-1-deficient cells. Neither ATP-binding cassette transporter G1 (ABCG1)- nor scavenger receptor class B type I (SR-BI)-mediated cholesterol efflux was affected. Cellular cholesterol efflux to apolipoprotein A-I was not significantly reduced in Cav-1(-/-) MPMs compared with wild-type MPMs. However, ABCA1-mediated cholesterol efflux was clearly more sensitive to the inhibitory effects of glyburide in Cav-1(-/-) MPMs versus WT MPMs. Taken together, these findings suggest that caveolin-1 plays an important role in the regulation of intracellular cholesterol homeostasis and can modulate the activity of other proteins that are involved in the regulation of intracellular cholesterol homeostasis.
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Affiliation(s)
- Philippe G Frank
- Department of Urology, and Albert Einstein Diabetes Research and Training Center, Albert Einstein College of Medicine, Bronx, New York, USA.
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Farrell B, Do Shope C, Brownell WE. Voltage-dependent capacitance of human embryonic kidney cells. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2006; 73:041930. [PMID: 16711859 PMCID: PMC2778024 DOI: 10.1103/physreve.73.041930] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2004] [Revised: 07/26/2005] [Indexed: 05/09/2023]
Abstract
We determine membrane capacitance, C as a function of dc voltage for the human embryonic kidney (HEK) cell. C was calculated from the admittance, Y, obtained during a voltage ramp when the HEK cell was held in whole-cell patch-clamp configuration. Y was determined at frequencies of 390.625 and from the measured current, i obtained with a dual-sinusoidal stimulus. We find that the fractional increase in the capacitance, C is small ( < 1%) and grows with the square of the voltage, Psi. C can be described by: C=C(0)(1+alpha(Psi+psi(s))2)[where C(0): Capacitance at 0 volts, psi(s): Difference in surface potential between cytoplasmic and extracellular leaflets and alpha: Proportionality constant]. We find that alpha and psi(s) are 0.120 (+/- 0.01) V(-2) and -0.073 (+/-0.017 V in solutions that contain ion channel blockers and 0.108 (+/- 0.29) V(-2) and -0.023 (+/- 0.009) V when 10 mM sodium salicylate was added to the extracellular solution. This suggests that salicylate does not affect the rate at which C grows with Psi, but reduces the charge asymmetry of the membrane. We also observe an additional linear differential capacitance of about (-46 fFV(-1)) in about 60% of the cells, this additional component acts simultaneously with the quadratic component and was not observed when salicylate was added to the solution. We suggest that the voltage dependent capacitance originates from electromechanical coupling either by electrostriction and/or Maxwell stress effects and estimate that a small electromechanical force (approximately equal to 1 pN) acts at physiological potentials. These results are relevant to understand the electromechanical coupling in outer hair cells (OHCs) of the mammalian cochlea, where an asymmetric bell-shaped C versus Psi relationship is observed upon application of a similar field. Prestin, a membrane protein expressed in OHCs is required to observe this function. When we compare the total charge contributions from HEK cell membrane (7 x 10(4) electrons, 10 pF cell) with that determined for prestin transfected cells (up to 5 x 10(6) electrons) we conclude that the charge contributions from the collective motion of membrane proteins and lipids in the field is dwarfed relative to that when prestin is present. We suggest that the capacitance-voltage relationships should be similar to that observed for HEK cells for OHCs that do not express prestin in their membranes.
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Affiliation(s)
- Brenda Farrell
- Department of Otolaryngology and Head and Neck Surgery, Baylor College of Medicine, Houston, TX 77030, USA.
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Truong TQ, Aubin D, Bourgeois P, Falstrault L, Brissette L. Opposite effect of caveolin-1 in the metabolism of high-density and low-density lipoproteins. Biochim Biophys Acta Mol Cell Biol Lipids 2006; 1761:24-36. [PMID: 16443388 DOI: 10.1016/j.bbalip.2005.12.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2005] [Revised: 12/06/2005] [Accepted: 12/12/2005] [Indexed: 11/21/2022]
Abstract
Receptors of the scavenger class B family were reported to be localized in caveolae, the cell surface microdomains rich in free cholesterol and glycosphyngolipids, which are characterized by the presence of caveolin-1. Parenchymal hepatic and hepatoma HepG2 cells express very low levels of caveolin-1. In the present study, stable transformants of HepG2 cells expressing caveolin-1 were generated to address the effect of caveolin-1 on receptor activity. Compared to normal cells, these cells show higher (125)I-bovine serum albumin (BSA) uptake and cholesterol efflux, two indicators of functional caveolae. By immunoprecipitation, cell fractionation and confocal analyses, we found that caveolin-1 is well colocalized with the cluster of differentiation-36 (CD36) and the low-density lipoprotein (LDL) receptor (LDLr) but to a lesser extent with the scavenger receptor class B type I (SR-BI) in HepG2 cells expressing caveolin-1. However, caveolin-1 expression favors the dimerization of SR-BI. Two clones of cells expressing caveolin-1 were investigated for their lipoprotein metabolism activity. Compared to normal cells, these cells show a 71-144% increase in (125)I-LDL degradation. The analysis of the cholesteryl esters (CE)-selective uptake (CE association minus protein association) revealed that the expression of caveolin-1 in HepG2 cells decreases by 59%-73% LDL-CE selective uptake and increases high-density lipoprotein (HDL)-CE selective uptake by 44%-66%. We conclude that the expression of caveolin-1 in HepG2 cells moves the balance of LDL degradation/CE selective uptake towards degradation and favors HDL-CE selective uptake. Thus, in the normal hepatic parenchymal situation where caveolin-1 is poorly expressed, LDL-CE selective uptake is the preferred pathway.
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Affiliation(s)
- To Quyen Truong
- Département des Sciences Biologiques, Université du Québec à Montréal, C.P. 8888, Succursale Centre-ville, Montréal, Québec, Canada H3C 3P8.
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Harder CJ, Vassiliou G, McBride HM, McPherson R. Hepatic SR-BI-mediated cholesteryl ester selective uptake occurs with unaltered efficiency in the absence of cellular energy. J Lipid Res 2005; 47:492-503. [PMID: 16339112 DOI: 10.1194/jlr.m500444-jlr200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Scavenger receptor class B type I (SR-BI) plays a critical role in the delivery of HDL cholesterol and cholesteryl esters (CEs) to liver and steroidogenic tissues by a selective process that does not result in significant degradation of HDL protein. Recently, SR-BI-mediated endocytosis and recycling of HDL have been demonstrated. However, it remains unclear whether efficient SR-BI-mediated selective uptake occurs strictly at the plasma membrane or at additional sites along its endocytic itinerary. To examine the requirement for SR-BI endocytosis in HDL selective uptake, we determined the effects of energy depletion on the levels of cell-associated HDL protein and CE in primary mouse hepatocytes. Compared with CHO cells, we observed a much larger energy-dependent effect on CE uptake in primary mouse hepatocytes. Although varying the levels of caveolin-1 and carboxyl ester lipase altered the efficiency of selective uptake, neither was able to account for the energy-dependent component of HDL-CE uptake. Finally, we demonstrate that the hepatocyte-specific, energy-dependent effects on HDL-apolipoprotein A-I and -CE uptake are independent of SR-BI and are not required to achieve efficient SR-BI-mediated selective uptake of CE. Together, these data support the conclusion that neither the intracellular trafficking of HDL nor any energy-dependent cellular process affects the ability of the cell to maximally acquire CE through SR-BI-mediated selective uptake from HDL.
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Affiliation(s)
- Chris J Harder
- Lipoprotein and Atherosclerosis Group, University of Ottawa Heart Institute, Ottawa, Ontario, Canada K1Y 4W7
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Wharton J, Meshulam T, Vallega G, Pilch P. Dissociation of Insulin Receptor Expression and Signaling from Caveolin-1 Expression. J Biol Chem 2005; 280:13483-6. [PMID: 15699039 DOI: 10.1074/jbc.m413891200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The presence of cell surface caveolin/caveolae has been postulated to influence the localization, expression levels, and kinase activity of numerous receptors, including the insulin receptor. However, there are conflicting data concerning the effects of caveolin on insulin receptor expression and function. To help clarify this issue, we created a gain of function situation by expressing caveolin-1 at various levels in HEK-293 cells where the endogenous level of caveolin-1 is very low. We generated four permanent lines of this cell expressing amounts of caveolin-1 ranging from 10 to 40 times that of parental cells. The amount of caveolin-1 in the human embryonic kidney cells expressing the highest caveolin levels is comparable with that of adipocytes, cells that naturally express one of the highest levels of caveolin-1. We measured insulin receptor amount and insulin-dependent receptor autophosphorylation as well as insulin receptor substrate 1 (IRS1) tyrosine phosphorylation as an index of insulin signaling. We found that the insulin receptor level was essentially the same in the parental and all four derived cell lines. Likewise, we determined that insulin-dependent insulin receptor and IRS1 tyrosine phosphorylation was not significantly different in the four cell lines representing parental, low, medium, and high levels of caveolin-1 expression. We conclude that insulin receptor expression and ligand-dependent signaling is independent of caveolin-1 expression.
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Affiliation(s)
- Jonathan Wharton
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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Frank PG, Lisanti MP. Caveolin-1 and caveolae in atherosclerosis: differential roles in fatty streak formation and neointimal hyperplasia. Curr Opin Lipidol 2004; 15:523-9. [PMID: 15361787 DOI: 10.1097/00041433-200410000-00005] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
PURPOSE OF REVIEW Caveolae are 50-100 nm cell surface plasma membrane invaginations observed in terminally differentiated cells. They are characterized by the presence of the protein marker caveolin-1. Caveolae and caveolin-1 are present in almost every cell type that has been implicated in the development of an atheroma. These include endothelial cells, macrophages, and smooth muscle cells. Caveolae and caveolin-1 are involved in regulating several signal transduction pathways and processes that play an important role in atherosclerosis. RECENT FINDINGS Several recent studies using genetically engineered mice (Cav-1 (-/-) null animals) have now clearly demonstrated a role for caveolin-1 and caveolae in the development of atherosclerosis. In fact, they suggest a rather complex one, either proatherogenic or antiatherogenic, depending on the cell type examined. For example, in endothelial cells, caveolin-1 and caveolae may play a proatherogenic role by promoting the transcytosis of LDL-cholesterol particles from the blood to the sub-endothelial space. In contrast, in smooth muscle cells, the ability of caveolin-1 to negatively regulate cell proliferation (neointimal hyperplasia) may have an antiatherogenic effect. SUMMARY Caveolin-1 and caveolae play an important role in several steps involved in the initiation of an atheroma. Development of new drugs that regulate caveolin-1 expression may be important in the prevention or treatment of atherosclerotic vascular disease.
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Affiliation(s)
- Philippe G Frank
- Department of Molecular Pharmacology and the Albert Einstein Diabetes Research and Training Center (DRTC), and Department of Urology, Albert Einstein College of Medicine, The Bronx, New York 10461, USA.
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Levy E, Ménard D, Suc I, Delvin E, Marcil V, Brissette L, Thibault L, Bendayan M. Ontogeny, immunolocalisation, distribution and function of SR-BI in the human intestine. J Cell Sci 2004; 117:327-37. [PMID: 14676281 DOI: 10.1242/jcs.00856] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Studies employing human fetal intestine have yielded remarkable information on the role of polarized enterocytes in fat absorption. In this report, we investigated the intestinal expression, spatiotemporal distributions, ontogeny and function of the scavenger receptor, Class B, Type I (SR-BI) that plays a crucial role in cholesterol homeostasis. SR-BI was detected as early as week 14 of gestation in all gut segments and was almost entirely confined to the absorptive epithelial cells. By using immunofluorescence staining, the distribution of SR-BI rarely appeared as a gradient, increasing from the developing crypt to the tip of the villus. Western blot showed high levels of immunodetectable SR-BI in the duodenum, which progressively decreased toward the distal colon. The high-resolution immunogold technique revealed labelling mainly over microvilli of the enterocyte. SR-BI was not associated with caveolin-1 and was not detectable in caveolae. In order to define the role of SR-BI in intestinal cholesterol absorption, Caco-2 cells were transfected with a constitutive expression vector (pZeoSV) containing human SR-BI cDNA inserted in an antisense orientation. As noted by immunoblotting and Protein A-gold techniques, stable transformants contained 40, 60 and 80% the SR-BI level of control Caco-2 cells and exhibited a proportional drop in free cholesterol uptake without altering the capture of phospholipids or cholesteryl ester. Confirmation of these data was obtained in intestinal organ culture where SR-BI antibodies lowered cholesterol uptake. These observations suggest that the human intestine possesses a developmental and regional SR-BI pattern of distribution, and extends our knowledge in SR-BI-mediated cholesterol transport.
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Affiliation(s)
- Emile Levy
- Department of Nutrition, Hôpital Sainte-Justine and University of Montreal, Montreal QC H3T 1C5, Canada.
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Connelly MA, Williams DL. Scavenger receptor BI: a scavenger receptor with a mission to transport high density lipoprotein lipids. Curr Opin Lipidol 2004; 15:287-95. [PMID: 15166784 DOI: 10.1097/00041433-200406000-00008] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW This review will survey recent findings on the cholesterol transport and scavenger functions of scavenger receptor BI. Although scavenger receptor BI and CD36 bind many of the same ligands, these two receptors have very specific lipid transport functions: CD36 facilitates the uptake of long chain fatty acids and SR-BI mediates the transport of cholesterol and cholesteryl ester from HDL particles. Scavenger receptor BI is a physiologically relevant HDL receptor that, along with HDL, is protective against cardiovascular disease. Its atheroprotective role has been hypothesized to be due to its function in the reverse cholesterol transport pathway. RECENT FINDINGS Recent studies suggest that scavenger receptor BI function is not only crucial for cholesterol delivery to the liver but is also important for cholesterol efflux at the vessel wall. Therefore, the receptor acts at both ends of the reverse cholesterol transport pathway. In addition, it stimulates nitric oxide production in endothelial cells, which may also contribute to its positive influence on the vasculature. Lastly, the glycoprotein was cloned as a scavenger receptor and in some cases is still thought to operate in this fashion. SUMMARY It will be interesting to follow future research on scavenger receptor BI that will delineate its functions in cholesterol transport as well as its scavenger functions. Additionally, we are only beginning to learn of the glycoprotein's effects on disease states besides atherosclerosis and cardiovascular disease.
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Affiliation(s)
- Margery A Connelly
- Department of Pharmacological Sciences, University Medical Center, State University of New York at Stony Brook, Stony Brook, NY 11794-8651, USA
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Fu Y, Hoang A, Escher G, Parton RG, Krozowski Z, Sviridov D. Expression of Caveolin-1 Enhances Cholesterol Efflux in Hepatic Cells. J Biol Chem 2004; 279:14140-6. [PMID: 14729661 DOI: 10.1074/jbc.m311061200] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
HepG2 cells were stably transfected with human caveolin-1 (HepG2/cav cells). Transfection resulted in expression of caveolin-1 mRNA, a high abundance of caveolin-1 protein, and the formation of caveolae on the plasma membrane. Cholesterol efflux from HepG2/cav cells was 280 and 45% higher than that from parent HepG2 cells when human plasma and human apoA-I, respectively, were used as acceptors. The difference in efflux was eliminated by treatment of cells with progesterone. There was no difference in cholesterol efflux to cyclodextrin. Cholesterol efflux from plasma membrane vesicles was similar for the two cell types. Transfection led to a 40% increase in the amount of plasma membrane cholesterol in cholesterol-rich domains (caveolae and/or rafts) and a 67% increase in the rate of cholesterol trafficking from intracellular compartments to these domains. Cholesterol biosynthesis in HepG2/cav cells was increased by 2-fold, and cholesterol esterification was reduced by 50% compared with parent HepG2 cells. The proliferation rate of transfected cells was significantly lower than that of non-transfected cells. Transfection did not affect expression of ABCA1 or the abundance of ABCA1 protein, but decreased secretion of apoA-I. We conclude that overexpression of caveolin-1 in hepatic cells stimulates cholesterol efflux by enhancing transfer of cholesterol to cholesterol-rich domains in the plasma membrane.
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Affiliation(s)
- Ying Fu
- Wynn Domain, Baker Heart Research Institute, Melbourne, Victoria 8008, Australia
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Abstract
Forward genetics is an unbiased methodology to discover new genes or functions of genes. At the present, the zebrafish is one of the few vertebrate systems where large-scale forward genetic studies are practical. Fluorescent lipid labeling of zebrafish larvae derived from families created from ENU-mutagenized fish enabled us to perform a large scale in vivo screen to identify mutants with perturbed lipid processing. With the aid of the zebrafish genome project, positional cloning of mutated genes with abnormal lipid metabolism can be accelerated. MO- and gripNA-based transient gene silencing is feasible in zebrafish embryos and provides a reverse genetic screening strategy to search for important lipid regulators. The advantages of using zebrafish as a vertebrate model to study lipid metabolism include its rapid external development and its optical clarity that enables the monitoring of biological processes. Large scale, high-throughput drug screening in vivo, especially for drugs that inhibit lipid absorption, can be easily achieved in this model. These zebrafish-based assays are important tools to understand aspects of lipid biology with significant clinical implications.
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Affiliation(s)
- Shiu-Ying Ho
- Department of Microbiology and Immunology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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Peng Y, Akmentin W, Connelly MA, Lund-Katz S, Phillips MC, Williams DL. Scavenger receptor BI (SR-BI) clustered on microvillar extensions suggests that this plasma membrane domain is a way station for cholesterol trafficking between cells and high-density lipoprotein. Mol Biol Cell 2003; 15:384-96. [PMID: 14528013 PMCID: PMC307555 DOI: 10.1091/mbc.e03-06-0445] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Receptor-mediated trafficking of cholesterol between lipoproteins and cells is a fundamental biological process at the organismal and cellular levels. In contrast to the well-studied pathway of LDL receptor-mediated endocytosis, little is known about the trafficking of high-density lipoprotein (HDL) cholesterol by the HDL receptor, scavenger receptor BI (SR-BI). SR-BI mediates HDL cholesteryl ester uptake in a process in which HDL lipids are selectively transferred to the cell membrane without the uptake and degradation of the HDL particle. We report here the cell surface locale where the trafficking of HDL cholesterol occurs. Fluorescence confocal microscopy showed SR-BI in patches and small extensions of the cell surface that were distinct from sites of caveolin-1 expression. Electron microscopy showed SR-BI in patches or clusters primarily on microvillar extensions of the plasma membrane. The organization of SR-BI in this manner suggests that this microvillar domain is a way station for cholesterol trafficking between HDL and cells. The types of phospholipids in this domain are unknown, but SR-BI is not strongly associated with classical membrane rafts rich in detergent-resistant saturated phospholipids. We speculate that SR-BI is in a more fluid membrane domain that will favor rapid cholesterol flux between the membrane and HDL.
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Affiliation(s)
- Yinan Peng
- Department of Pharmacological Sciences, University Medical Center, State University of New York at Stony Brook, Stony Brook, New York 11794, USA
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Trigatti BL, Krieger M, Rigotti A. Influence of the HDL receptor SR-BI on lipoprotein metabolism and atherosclerosis. Arterioscler Thromb Vasc Biol 2003; 23:1732-8. [PMID: 12920050 DOI: 10.1161/01.atv.0000091363.28501.84] [Citation(s) in RCA: 183] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The scavenger receptor class B type I (SR-BI) was the first molecularly well-defined cell-surface HDL receptor to be described. SR-BI mediates selective HDL cholesterol uptake by formation of a productive lipoprotein/receptor complex, which requires specific structural domains and conformation states of apolipoprotein A-I present in HDL particles. SR-BI is abundantly expressed in several tissues, including the liver, where its expression is regulated by various mechanisms, including the transcriptional activity of nuclear receptors. The importance of SR-BI in overall HDL cholesterol metabolism and its antiatherogenic activity in vivo has been definitively established by SR-BI gene manipulation in mice. Remarkably, SR-BI/apolipoprotein E double-knockout mice develop complex coronary artery disease, myocardial infarction, and heart failure. Additional studies should help to define the importance of SR-BI in human health and disease.
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Schmid KE, Davidson WS, Myatt L, Woollett LA. Transport of cholesterol across a BeWo cell monolayer: implications for net transport of sterol from maternal to fetal circulation. J Lipid Res 2003; 44:1909-18. [PMID: 12897187 DOI: 10.1194/jlr.m300126-jlr200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The placental transport of various compounds, such as glucose and fatty acids, has been well studied. However, the transport of cholesterol, a sterol essential for proper fetal development, remains undefined in the placenta. Therefore, the purpose of these studies was to examine the transport of cholesterol across a placental monolayer and its uptake by various cholesterol acceptors. BeWo cells, which originated from a human choriocarcinoma, were grown on transwells for 3 days to form a confluent monolayer. The apical side of the cells was radiolabeled with either free cholesterol or LDL cholesteryl ester. After 24 h, the radiolabel was removed and cholesterol acceptors were added to the basolateral chamber. Cholesterol was found to be taken up by the apical surface of the placental monolayer, transported to the basolateral surface of the cell, and effluxed to fetal human serum, fetal HDL, or phospholipid vesicles, but not to apolipoprotein A-I. In addition, increasing the cellular cholesterol concentration further increased the amount of cholesterol transported to the basolateral acceptors. These are the first studies to demonstrate the movement of cholesterol across a placental cell from the maternal circulation (apical side) to the fetal circulation (basolateral side).
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Affiliation(s)
- Kara E Schmid
- Department of Pathology and Laboratory Medicine, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267, USA
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Rigotti A, Miettinen HE, Krieger M. The role of the high-density lipoprotein receptor SR-BI in the lipid metabolism of endocrine and other tissues. Endocr Rev 2003; 24:357-87. [PMID: 12788804 DOI: 10.1210/er.2001-0037] [Citation(s) in RCA: 313] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Because cholesterol is a precursor for the synthesis of steroid hormones, steroidogenic tissues have evolved multiple pathways to ensure adequate supplies of cholesterol. These include synthesis, storage as cholesteryl esters, and import from lipoproteins. In addition to endocytosis via members of the low-density lipoprotein receptor superfamily, steroidogenic cells acquire cholesterol from lipoproteins by selective lipid uptake. This pathway, which does not involve lysosomal degradation of the lipoprotein, is mediated by the scavenger receptor class B type I (SR-BI). SR-BI is highly expressed in steroidogenic cells, where its expression is regulated by various trophic hormones, as well as in the liver. Studies of genetically manipulated strains of mice have established that SR-BI plays a key role in regulating lipoprotein metabolism and cholesterol transport to steroidogenic tissues and to the liver for biliary secretion. In addition, analysis of SR-BI-deficient mice has shown that SR-BI expression is important for alpha-tocopherol and nitric oxide metabolism, as well as normal red blood cell maturation and female fertility. These mouse models have also revealed that SR-BI can protect against atherosclerosis. If SR-BI plays similar physiological and pathophysiological roles in humans, it may be an attractive target for therapeutic intervention in cardiovascular and reproductive diseases.
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Affiliation(s)
- Attilio Rigotti
- Departamento de Gastroenterología, Facultad de Medicina, Pontificia Universidad Católica, Santiago, Chile
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