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Lv Q, Zhao H. The association of metabolic dysfunction-associated steatotic liver disease (MASLD) with the risk of myocardial infarction: a systematic review and meta-analysis. Ann Med 2024; 56:2306192. [PMID: 38253023 PMCID: PMC10810647 DOI: 10.1080/07853890.2024.2306192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 01/11/2024] [Indexed: 01/24/2024] Open
Abstract
Objective While studies have documented how metabolic dysfunction-associated steatotic liver disease (MASLD) can contribute to cardiovascular disease (CVD), whether MASLD is associated with myocardial infarction (MI) remains debateable. Herein, we systematically reviewed published articles and performed a meta-analysis to determine the relationship between MASLD and MI risk.Methods PubMed, MEDLINE, Embase, Web of Science, CNKI, CBM, VIP, and WanFang databases were searched, and the DerSimonian Laird method was used to obtain hazard ratios (HRs) for binary variables to assess the correlation between MASLD and MI risk. Subgroup analyses for the study region, MASLD diagnosis, quality score, study design, and follow-up time were conducted simultaneously for the selected studies retrieved from the time of database establishment to March 2022. All study procedures were independently conducted by two investigators.Results The final analysis included seven articles, including eight prospective and two retrospective cohort studies. The MI risk was higher among MASLD patients than among non-MASLD patients (HR = 1.26; 95% CI: 1.08-1.47, p = 0.003). The results of the subgroup analysis of the study region revealed an association of MASLD with MI risk among Americans and Asians, but not in Europeans. Subgroup analyses of MASLD diagnosis showed that ultrasonography and other (fatty liver index[FLI] and computed tomography [CT)]) diagnostic methods, but not international classification of disease (ICD), increased the risk of MI. Subgroup analysis of the study design demonstrated a stronger relationship between MASLD and MI in retrospective studies but not in prospective studies. Subgroup analysis based on the follow-up duration revealed the association of MASLD with MI risk in cases with < 3 years of follow-up but not with ≥3 years of follow-up.Conclusion MASLD increases the risk of MI, independent of traditional risk factors.
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Affiliation(s)
- Qiong Lv
- Department of Electrocardiogram, The First Affiliated Hospital, and College of Clinical Medicine of Henan University of Science and Technology, Luoyang, China
| | - Huashan Zhao
- Department of General Medicine, The First Affiliated Hospital, and College of Clinical Medicine of Henan University of Science and Technology, Luoyang, China
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Li J, Ge X, Liu X, Fu C, Miao J, Zhao W, Miao L, Hang D. Serum apolipoproteins and mortality risk: evidence from observational and Mendelian randomization analyses. Am J Clin Nutr 2024; 119:981-989. [PMID: 38211689 DOI: 10.1016/j.ajcnut.2024.01.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 01/02/2024] [Accepted: 01/08/2024] [Indexed: 01/13/2024] Open
Abstract
BACKGROUND Apolipoproteins (APOs) have emerged as significant players in lipid metabolism that affects the risk of chronic disease. However, the impact of circulating APO concentrations on premature death remains undetermined. OBJECTIVES This study aimed to investigate the associations of serum APOs with all-cause, cardiovascular disease (CVD)-related, and cancer-related mortality. METHODS We included 340,737 participants who had serum APO measurements from the UK Biobank. Restricted cubic splines and multivariable Cox regression models were used to assess the associations between APOs and all-cause and cause-specific mortality by computing hazard ratios (HRs) and 95% confidence intervals (CIs). Based on 1-sample Mendelian randomization (MR) design, including 398,457 participants of White ancestry who had genotyping data from the UK Biobank, we performed instrumental variable analysis with 2-stage least squares regression to assess the association between genetically predicted APOs and mortality. RESULTS After adjusting for potential confounders including high-density and low-density lipoprotein particles, we observed nonlinear inverse relationships of APOA1 with all-cause, CVD-related, and cancer-related mortality (P-nonlinear < 0.001). By contrast, positive relationships were observed for APOB and all-cause (P-nonlinear < 0.001), CVD-related (P-linear < 0.001), and cancer-related (P-linear = 0.03) mortality. MR analysis showed consistent results, except that the association between APOB and cancer mortality was null. Furthermore, both observational and MR analyses found an inverse association between APOA1 and lung cancer-related mortality (HR comparing extreme deciles: 0.46; 95% CI: 0.26, 0.80; and HR: 0.78; 95% CI: 0.63, 0.97, respectively). CONCLUSIONS Our findings indicate that circulating APOA1 has potential beneficial effects on all-cause, CVD-related, and lung cancer-related death risk, whereas APOB may confer detrimental effects on all-cause and CVD-related death risk.
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Affiliation(s)
- Jiacong Li
- Department of Epidemiology, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Xianxiu Ge
- Medical Center for Digestive Diseases, Second Affiliated Hospital, Nanjing Medical University, Nanjing, China
| | - Xinyi Liu
- Department of Epidemiology, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Chengqu Fu
- Department of Epidemiology, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Junyan Miao
- Department of Epidemiology, School of Public Health, Nanjing Medical University, Nanjing, China
| | - Wei Zhao
- Center of Clinical Laboratory Science, The Affiliated Cancer Hospital of Nanjing Medical University & Jiangsu Cancer Hospital & Jiangsu Institute of Cancer Research, Nanjing, China.
| | - Lin Miao
- Medical Center for Digestive Diseases, Second Affiliated Hospital, Nanjing Medical University, Nanjing, China.
| | - Dong Hang
- Department of Epidemiology, School of Public Health, Nanjing Medical University, Nanjing, China; Jiangsu Key Lab of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine and China International Cooperation Center for Environment and Human Health, Gusu School, Nanjing Medical University, Nanjing, China
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Fu L, Guldiken N, Remih K, Karl AS, Preisinger C, Strnad P. Serum/Plasma Proteome in Non-Malignant Liver Disease. Int J Mol Sci 2024; 25:2008. [PMID: 38396688 PMCID: PMC10889128 DOI: 10.3390/ijms25042008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 01/31/2024] [Accepted: 02/03/2024] [Indexed: 02/25/2024] Open
Abstract
The liver is the central metabolic organ and produces 85-90% of the proteins found in plasma. Accordingly, the plasma proteome is an attractive source of liver disease biomarkers that reflects the different cell types present in this organ, as well as the processes such as responses to acute and chronic injury or the formation of an extracellular matrix. In the first part, we summarize the biomarkers routinely used in clinical evaluations and their biological relevance in the different stages of non-malignant liver disease. Later, we describe the current proteomic approaches, including mass spectrometry and affinity-based techniques, that allow a more comprehensive assessment of the liver function but also require complex data processing. The many approaches of analysis and interpretation and their potential caveats are delineated. While these advances hold the promise to transform our understanding of liver diseases and support the development and validation of new liver-related drugs, an interdisciplinary collaboration is needed.
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Affiliation(s)
- Lei Fu
- Department of Internal Medicine III, Gastroenterology, Metabolic Diseases and Intensive Care, University Hospital RWTH Aachen, Pauwelsstraße 30, 52074 Aachen, Germany; (L.F.); (N.G.); (K.R.); (A.S.K.)
| | - Nurdan Guldiken
- Department of Internal Medicine III, Gastroenterology, Metabolic Diseases and Intensive Care, University Hospital RWTH Aachen, Pauwelsstraße 30, 52074 Aachen, Germany; (L.F.); (N.G.); (K.R.); (A.S.K.)
| | - Katharina Remih
- Department of Internal Medicine III, Gastroenterology, Metabolic Diseases and Intensive Care, University Hospital RWTH Aachen, Pauwelsstraße 30, 52074 Aachen, Germany; (L.F.); (N.G.); (K.R.); (A.S.K.)
| | - Anna Sophie Karl
- Department of Internal Medicine III, Gastroenterology, Metabolic Diseases and Intensive Care, University Hospital RWTH Aachen, Pauwelsstraße 30, 52074 Aachen, Germany; (L.F.); (N.G.); (K.R.); (A.S.K.)
| | - Christian Preisinger
- Proteomics Facility, Interdisciplinary Centre for Clinical Research (IZKF), Medical School, RWTH Aachen University, Pauwelsstraße 30, 52074 Aachen, Germany;
| | - Pavel Strnad
- Department of Internal Medicine III, Gastroenterology, Metabolic Diseases and Intensive Care, University Hospital RWTH Aachen, Pauwelsstraße 30, 52074 Aachen, Germany; (L.F.); (N.G.); (K.R.); (A.S.K.)
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Martella N, Colardo M, Sergio W, Petraroia M, Varone M, Pensabene D, Russo M, Di Bartolomeo S, Ranalli G, Saviano G, Segatto M. Lavender Essential Oil Modulates Hepatic Cholesterol Metabolism in HepG2 Cells. Curr Issues Mol Biol 2023; 45:364-378. [PMID: 36661512 PMCID: PMC9857966 DOI: 10.3390/cimb45010026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 12/23/2022] [Accepted: 12/28/2022] [Indexed: 01/06/2023] Open
Abstract
Cholesterol is an essential lipid that guarantees several biological processes in eukaryotic cells. Its metabolism is regulated by a complex protein network that could be significantly influenced by numerous exogenous sources, such as essential oils (EOs). For instance, it has been speculated that monoterpenoid and sesquiterpenoid compounds contained in lavender essential oil (LEO) may exert important hypocholesterolemic activities. However, the molecular mechanisms by which LEO influences cholesterol homeostasis are not characterized. In this work, we evaluated the ability of LEO to regulate the protein network that controls cholesterol metabolism in the HepG2 cell line. The main findings indicate that LEO administration increases intracellular cholesterol content. Concurrently, LEO affects the expression of proteins involved in cholesterol uptake, biosynthesis, and trafficking. These effects are partially mediated by terpinene-4-ol, one of the most abundant compounds in LEO. These results demonstrate that LEO modulates cholesterol metabolism in hepatic cells.
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Affiliation(s)
- Noemi Martella
- Department of Biosciences and Territory, University of Molise, Contrada Fonte Lappone, 86090 Pesche, Italy
| | - Mayra Colardo
- Department of Biosciences and Territory, University of Molise, Contrada Fonte Lappone, 86090 Pesche, Italy
| | - William Sergio
- Department of Biosciences and Territory, University of Molise, Contrada Fonte Lappone, 86090 Pesche, Italy
| | - Michele Petraroia
- Department of Biosciences and Territory, University of Molise, Contrada Fonte Lappone, 86090 Pesche, Italy
| | - Michela Varone
- Department of Biosciences and Territory, University of Molise, Contrada Fonte Lappone, 86090 Pesche, Italy
| | - Daniele Pensabene
- Department of Science, University Roma Tre, Viale Marconi 446, 00146 Rome, Italy
| | - Miriam Russo
- Department of Biosciences and Territory, University of Molise, Contrada Fonte Lappone, 86090 Pesche, Italy
| | - Sabrina Di Bartolomeo
- Department of Biosciences and Territory, University of Molise, Contrada Fonte Lappone, 86090 Pesche, Italy
| | - Giancarlo Ranalli
- Department of Biosciences and Territory, University of Molise, Contrada Fonte Lappone, 86090 Pesche, Italy
| | - Gabriella Saviano
- Department of Biosciences and Territory, University of Molise, Contrada Fonte Lappone, 86090 Pesche, Italy
- Correspondence: (G.S.); (M.S.)
| | - Marco Segatto
- Department of Biosciences and Territory, University of Molise, Contrada Fonte Lappone, 86090 Pesche, Italy
- Correspondence: (G.S.); (M.S.)
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Roles of Bromodomain Extra Terminal Proteins in Metabolic Signaling and Diseases. Pharmaceuticals (Basel) 2022; 15:ph15081032. [PMID: 36015180 PMCID: PMC9414451 DOI: 10.3390/ph15081032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Revised: 07/20/2022] [Accepted: 07/25/2022] [Indexed: 11/16/2022] Open
Abstract
BET proteins, which recognize and bind to acetylated histones, play a key role in transcriptional regulation. The development of chemical BET inhibitors in 2010 greatly facilitated the study of these proteins. BETs play crucial roles in cancer, inflammation, heart failure, and fibrosis. In particular, BETs may be involved in regulating metabolic processes, such as adipogenesis and metaflammation, which are under tight transcriptional regulation. In addition, acetyl-CoA links energy metabolism with epigenetic modification through lysine acetylation, which creates docking sites for BET. Given this, it is possible that the ambient energy status may dictate metabolic gene transcription via a BET-dependent mechanism. Indeed, recent studies have reported that various BET proteins are involved in both metabolic signaling regulation and disease. Here, we discuss some of the most recent information on BET proteins and their regulation of the metabolism in both cellular and animal models. Further, we summarize data from some randomized clinical trials evaluating BET inhibitors for the treatment of metabolic diseases.
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Guo L, Chen Y, Li H, Yin F, Ge M, Hu L, Zi M, Qin Z, He Y. Telomere length is maternally inherited and associated with lipid metabolism in Chinese population. Aging (Albany NY) 2022; 14:354-367. [PMID: 34995210 PMCID: PMC8791204 DOI: 10.18632/aging.203810] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 12/25/2021] [Indexed: 11/25/2022]
Abstract
Telomere is a unique DNA-protein complex which covers the ends of chromosomes to avoid end fusion and maintain the stability and integrity of chromosomes. Telomere length (TL) shortening has been linked to aging and various age-related diseases in humans. Here we recruited a total of 1031 Chinese individuals aged between 12 and 111 years, including 108 families with parents and their offspring. DNA was extracted from peripheral white blood cells and TL was measured by quantitative PCR (qPCR). We explored the associations of TL with age, gender and clinical variables, and tested the parental effects on TL variation. First, we found that TL was shortened with age, however, TL was better maintained in females than males. Second, there was a robust association of TL between mother and offspring, but not between father and their offspring. In addition, TL was inversely associated with visceral fat index in females, and positively associated with apolipoprotein A levels. Knockdown of the key genes for lipid metabolism (PNPLA2 and CPT1) shortened the TL in HepG2 cells. These findings indicate that TL is maternally inherited, and impairment of lipid metabolism may contribute to the TL shortening in the Chinese population.
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Affiliation(s)
- Liyun Guo
- Key Laboratory of Healthy Aging Research of Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650201, China
- Department of Pharmacology and Laboratory of Aging and Nervous Diseases and Jiangsu Key Laboratory of Neuropsychiatric Diseases, College of Pharmaceutical Sciences, Soochow University, Suzhou 215123, China
| | - Yajuan Chen
- School of Rehabilitation, Kunming Medical University, Kunming 650500, China
| | - Huiqin Li
- Key Laboratory of Healthy Aging Research of Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650201, China
| | - Fanqian Yin
- Key Laboratory of Healthy Aging Research of Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650201, China
- Kunming College of Life Science, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Mingxia Ge
- Key Laboratory of Healthy Aging Research of Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650201, China
- Kunming College of Life Science, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Li Hu
- Key Laboratory of Healthy Aging Research of Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650201, China
- College of Basic Medicine and Life Sciences, Hainan Medical University, Haikou 571199, China
| | - Meiting Zi
- Key Laboratory of Healthy Aging Research of Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650201, China
| | - Zhenghong Qin
- Department of Pharmacology and Laboratory of Aging and Nervous Diseases and Jiangsu Key Laboratory of Neuropsychiatric Diseases, College of Pharmaceutical Sciences, Soochow University, Suzhou 215123, China
| | - Yonghan He
- Key Laboratory of Healthy Aging Research of Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650201, China
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Yang YJ, Jung MH, Jeong SH, Hong YP, Kim YI, An SJ. The Association between Nonalcoholic Fatty Liver Disease and Stroke: Results from the Korean Genome and Epidemiology Study (KoGES). INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17249568. [PMID: 33371282 PMCID: PMC7765788 DOI: 10.3390/ijerph17249568] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 12/14/2020] [Accepted: 12/16/2020] [Indexed: 02/07/2023]
Abstract
(1) Background: Non-alcoholic fatty liver disease (NAFLD) is associated with various cardiometabolic diseases. However, the association between NAFLD and stroke is not well known. The purpose of our study is to reveal the relationship between NAFLD and Stroke incidence. (2) Methods: Using data from a Korean prospective cohort study, we excluded participants with heavy alcohol consumption and a history of stroke; hence, 7964 adults aged 40–69 years were included in this study. According to their fatty liver index (FLI), participants were divided into three groups: <30 (n = 4550, non-NAFLD), 30–59.9 (n = 2229, intermediate), and ≥60 (n = 1185, NAFLD). The incidence of stroke according to the degree of FLI was evaluated using the Cox proportional hazard model. (3) Results: During the 12-year follow-up period, 168 strokes occurred. A graded association between NAFLD and stroke incidence was observed, i.e., 1.7% (n = 76), 2.5% (n = 56), and 3.0% (n = 36) for non-NAFLD, intermediate, and NAFLD FLI groups, respectively. After adjusting for confounding variables and compared to the risk of stroke in the non-NAFLD group, the risk of stroke in the NAFLD group was the highest (hazard ratio [HR]: 1.98, 95% confidence interval [CI]: 1.17–3.34), followed by the risk of stroke in the intermediate group (HR: 1.41, 95% CI: 0.94–2.21) (p for trend < 0.001). However, the level of aspartate aminotransferase, alanine aminotransferase, or gamma-glutamyltransferase alone did not show any significant association with stroke. (4) Conclusions: This study demonstrated that the risk of stroke incidence gradually increased with the degree of FLI. Individuals with NAFLD should be properly counseled and monitored for risk for stroke.
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Affiliation(s)
- Yun-Jung Yang
- Institute of Biomedical Science, Catholic Kwandong University International St. Mary’s Hospital, Incheon 22711, Korea;
| | - Mi-Hyang Jung
- Cardiovascular Center, Dongtan Sacred Heart Hospital, Hallym University College of Medicine, Hwaseong-Si 18450, Korea;
| | - Seok-Hoo Jeong
- Division of Gastroenterology, Department of Internal Medicine, Catholic Kwandong University International St. Mary’s Hospital, Incheon 22711, Korea;
| | - Yeon-Pyo Hong
- Department of Preventive Medicine, College of Medicine, Chung-Ang University, Seoul 06974, Korea;
| | - Yeong In Kim
- Department of Neurology, Catholic Kwandong University International St. Mary’s Hospital, Incheon 22711, Korea;
| | - Sang Joon An
- Department of Neurology, Catholic Kwandong University International St. Mary’s Hospital, Incheon 22711, Korea;
- Correspondence: or ; Tel.: +82-32-290-2994; Fax: +82-32-290-3879
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Smith O, Dunshea G, Sinding MHS, Fedorov S, Germonpre M, Bocherens H, Gilbert MTP. Ancient RNA from Late Pleistocene permafrost and historical canids shows tissue-specific transcriptome survival. PLoS Biol 2019; 17:e3000166. [PMID: 31361744 PMCID: PMC6667121 DOI: 10.1371/journal.pbio.3000166] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 06/25/2019] [Indexed: 01/31/2023] Open
Abstract
While sequencing ancient DNA (aDNA) from archaeological material is now commonplace, very few attempts to sequence ancient transcriptomes have been made, even from typically stable deposition environments such as permafrost. This is presumably due to assumptions that RNA completely degrades relatively quickly, particularly when dealing with autolytic, nuclease-rich mammalian tissues. However, given the recent successes in sequencing ancient RNA (aRNA) from various sources including plants and animals, we suspect that these assumptions may be incorrect or exaggerated. To challenge the underlying dogma, we generated shotgun RNA data from sources that might normally be dismissed for such study. Here, we present aRNA data generated from two historical wolf skins, and permafrost-preserved liver tissue of a 14,300-year-old Pleistocene canid. Not only is the latter the oldest RNA ever to be sequenced, but it also shows evidence of biologically relevant tissue specificity and close similarity to equivalent data derived from modern-day control tissue. Other hallmarks of RNA sequencing (RNA-seq) data such as exon-exon junction presence and high endogenous ribosomal RNA (rRNA) content confirms our data’s authenticity. By performing independent technical library replicates using two high-throughput sequencing platforms, we show not only that aRNA can survive for extended periods in mammalian tissues but also that it has potential for tissue identification. aRNA also has possible further potential, such as identifying in vivo genome activity and adaptation, when sequenced using this technology. Ancient DNA is known to survive in cold environments for tens of millennia, but it is assumed that ancient RNA could not persist in such a way due to its relative instability. However, this study shows that under permafrost conditions, ancient RNA can survive well enough to show tissue specificity even in mammalian soft tissues.
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Affiliation(s)
- Oliver Smith
- Section for Evogenomics, The Globe Institute, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- * E-mail:
| | - Glenn Dunshea
- Section for Evogenomics, The Globe Institute, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mikkel-Holger S. Sinding
- Section for Evogenomics, The Globe Institute, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Greenland Institute of Natural Resources, Nuuk, Greenland
| | - Sergey Fedorov
- Mammoth Museum, Institute of Applied Ecology of the North of the North-Eastern Federal University, Yakutsk, Russia
| | - Mietje Germonpre
- Directorate Earth and History of Life, Royal Belgian Institute of Natural Science, Brussels, Belgium
| | - Hervé Bocherens
- Department of Geosciences, Palaeobiology, University of Tübingen, Tübingen, Germany
- Senckenberg Centre for Human Evolution and Palaeoenvironment, University of Tübingen, Tübingen, Germany
| | - M. T. P. Gilbert
- Section for Evogenomics, The Globe Institute, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Norwegian University of Science and Technology, University Museum, Trondheim, Norway
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Non-alcoholic fatty liver disease, liver biomarkers and stroke risk: The Reasons for Geographic and Racial Differences in Stroke cohort. PLoS One 2018. [PMID: 29529073 PMCID: PMC5847237 DOI: 10.1371/journal.pone.0194153] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Background and purpose Liver disease, particularly non-alcoholic fatty liver disease (NAFLD), is a risk factor for cardiovascular disease, but little is known about its relationship with ischemic stroke. Methods In the Reasons for Geographic and Racial Differences in Stroke (REGARDS) cohort of 30,239 American black and white adults, we assessed baseline NAFLD as fatty liver index (FLI) >60, and assessed liver biomarkers aspartate aminotransferase (AST), alanine aminotransferase (ALT), γ-glutamyl transpeptidase (GGT), and the AST/ALT ratio and risk of incident ischemic stroke over 5.8 years using a case-cohort study design. Results Considering 572 strokes and a 1,017-person cohort sample, NAFLD was inversely associated with stroke risk in men (HR: 0.50; 95% CI: 0.26, 0.96), as was being in the highest ALT quintile versus the lowest (HR: 0.39; 95% CI: 0.19, 0.78) and the highest versus lowest GGT quintile (HR: 0.45, 95% CI: 0.24, 0.85), but not in women. Conversely, FLI score above the 90th percentile was associated with increased stroke risk among women (HR: 2.26; 95% CI: 1.14–4.47), but not men. AST was not associated with stroke risk in either sex. AST/ALT ratio >2 was strongly associated with increased stroke risk in whites, but not blacks (HRs: 3.64; 95% CI: 1.42–9.35 and 0.97; 95% CI: 0.45–1.99, respectively; p for interaction = 0.03). Conclusions The relationships between NAFLD, liver biomarkers, and ischemic stroke are complex, and sex and race differences we observed require further study and confirmation.
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Abnormalities of Lipoprotein Levels in Liver Cirrhosis: Clinical Relevance. Dig Dis Sci 2018; 63:16-26. [PMID: 29177578 DOI: 10.1007/s10620-017-4862-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Accepted: 11/19/2017] [Indexed: 12/17/2022]
Abstract
Progressive lipoprotein impairment occurs in liver cirrhosis and is associated with increased morbidity and mortality. The present review aims to summarize the current evidence regarding the prognostic value of lipoprotein abnormalities in liver cirrhosis and to address the need of a better prognostic stratification of patients, including lipoprotein profile assessment. Low levels of lipoproteins are usual in cirrhosis. Much evidence supports the prognostic role of hypolipidemia in cirrhotic patients. In particular, hypocholesterolemia represents an independent predictor of survival in cirrhosis. In cirrhotic patients, lipoprotein impairment is associated with several complications: infections, malnutrition, adrenal function, and spur cell anemia. Alterations of liver function are associated with modifications of circulating lipids. Decreased levels of lipoproteins significantly impact the survival of cirrhotic patients and play an important role in the pathogenesis of some cirrhosis-related complications.
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Heffner KM, Hizal DB, Yerganian GS, Kumar A, Can Ö, O’Meally R, Cole R, Chaerkady R, Wu H, Bowen MA, Betenbaugh MJ. Lessons from the Hamster: Cricetulus griseus Tissue and CHO Cell Line Proteome Comparison. J Proteome Res 2017; 16:3672-3687. [DOI: 10.1021/acs.jproteome.7b00382] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
| | | | | | - Amit Kumar
- Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Özge Can
- Acibadem University, Medical Biochemistry, Istanbul, Maltepe, Turkey
| | - Robert O’Meally
- Johns Hopkins Medical Institute, Baltimore, Maryland 21205, United States
| | - Robert Cole
- Johns Hopkins Medical Institute, Baltimore, Maryland 21205, United States
| | | | - Herren Wu
- MedImmune, Gaithersburg, Maryland 20878, United States
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Xu YY, Du F, Meng B, Xie GH, Cao J, Fan D, Yu H. Hepatic overexpression of methionine sulfoxide reductase A reduces atherosclerosis in apolipoprotein E-deficient mice. J Lipid Res 2015; 56:1891-900. [PMID: 26318157 PMCID: PMC4583078 DOI: 10.1194/jlr.m058776] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Indexed: 12/21/2022] Open
Abstract
Methionine sulfoxide reductase A (MsrA), a specific enzyme that converts methionine-S-sulfoxide to methionine, plays an important role in the regulation of protein function and the maintenance of redox homeostasis. In this study, we examined the impact of hepatic MsrA overexpression on lipid metabolism and atherosclerosis in apoE-deficient (apoE−/−) mice. In vitro study showed that in HepG2 cells, lentivirus-mediated human MsrA (hMsrA) overexpression upregulated the expression levels of several key lipoprotein-metabolism-related genes such as liver X receptor α, scavenger receptor class B type I, and ABCA1. ApoE−/− mice were intravenously injected with lentivirus to achieve high-level hMsrA expression predominantly in the liver. We found that hepatic hMsrA expression significantly reduced plasma VLDL/LDL levels, improved plasma superoxide dismutase, and paraoxonase-1 activities, and decreased plasma serum amyloid A level in apoE−/− mice fed a Western diet, by significantly altering the expression of several genes in the liver involving cholesterol selective uptake, conversion and excretion into bile, TG biosynthesis, and inflammation. Moreover, overexpression of hMsrA resulted in reduced hepatic steatosis and aortic atherosclerosis. These results suggest that hepatic MsrA may be an effective therapeutic target for ameliorating dyslipidemia and reducing atherosclerosis-related cardiovascular diseases.
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Affiliation(s)
- Yan-Yong Xu
- Department of Biochemistry and Molecular Biology Wuhan University School of Basic Medical Sciences, Wuhan, China
| | - Fen Du
- Department of Biochemistry and Molecular Biology Wuhan University School of Basic Medical Sciences, Wuhan, China Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan University School of Basic Medical Sciences, Wuhan, China Department of Cell Biology and Anatomy, School of Medicine, University of South Carolina, Columbia, SC
| | - Bing Meng
- Department of Biochemistry and Molecular Biology Wuhan University School of Basic Medical Sciences, Wuhan, China
| | - Guang-Hui Xie
- Department of Biochemistry and Molecular Biology Wuhan University School of Basic Medical Sciences, Wuhan, China
| | - Jia Cao
- Department of Biochemistry and Molecular Biology Wuhan University School of Basic Medical Sciences, Wuhan, China
| | - Daping Fan
- Department of Cell Biology and Anatomy, School of Medicine, University of South Carolina, Columbia, SC
| | - Hong Yu
- Department of Biochemistry and Molecular Biology Wuhan University School of Basic Medical Sciences, Wuhan, China Hubei Provincial Key Laboratory of Developmentally Originated Disease, Wuhan University School of Basic Medical Sciences, Wuhan, China
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13
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Petropolis DB, Faust DM, Deep Jhingan G, Guillen N. A new human 3D-liver model unravels the role of galectins in liver infection by the parasite Entamoeba histolytica. PLoS Pathog 2014; 10:e1004381. [PMID: 25211477 PMCID: PMC4161482 DOI: 10.1371/journal.ppat.1004381] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Accepted: 08/01/2014] [Indexed: 11/28/2022] Open
Abstract
Investigations of human parasitic diseases depend on the availability of appropriate in vivo animal models and ex vivo experimental systems, and are particularly difficult for pathogens whose exclusive natural hosts are humans, such as Entamoeba histolytica, the protozoan parasite responsible for amoebiasis. This common infectious human disease affects the intestine and liver. In the liver sinusoids E. histolytica crosses the endothelium and penetrates into the parenchyma, with the concomitant initiation of inflammatory foci and subsequent abscess formation. Studying factors responsible for human liver infection is hampered by the complexity of the hepatic environment and by the restrictions inherent to the use of human samples. Therefore, we built a human 3D-liver in vitro model composed of cultured liver sinusoidal endothelial cells and hepatocytes in a 3D collagen-I matrix sandwich. We determined the presence of important hepatic markers and demonstrated that the cell layers function as a biological barrier. E. histolytica invasion was assessed using wild-type strains and amoebae with altered virulence or different adhesive properties. We showed for the first time the dependence of endothelium crossing upon amoebic Gal/GalNAc lectin. The 3D-liver model enabled the molecular analysis of human cell responses, suggesting for the first time a crucial role of human galectins in parasite adhesion to the endothelial cells, which was confirmed by siRNA knockdown of galectin-1. Levels of several pro-inflammatory cytokines, including galectin-1 and -3, were highly increased upon contact of E. histolytica with the 3D-liver model. The presence of galectin-1 and -3 in the extracellular medium stimulated pro-inflammatory cytokine release, suggesting a further role for human galectins in the onset of the hepatic inflammatory response. These new findings are relevant for a better understanding of human liver infection by E. histolytica. The study of liver infection is based on animal models, but the animal physiology does not always reflect the reality of the human host. This is particularly true for pathogens whose exclusive natural hosts are humans, such as Entamoeba histolytica, the protozoan parasite responsible for amoebiasis. Here, we constructed an experimental human 3D-liver model able to reproduce the first steps of amoebic hepatic infection (barrier crossing, tissue migration and pro-inflammatory reaction). Using this 3D-liver model we were able to decipher the first stages of hepatic invasion by E. histolytica and to unravel the role played by galectin-1 and galectin-3 during amoebic hepatic adhesion and pro-inflammatory reaction. Moreover, the model enables analysis usually not possible with in vivo samples, such as the quantification of pro-inflammatory cytokines released inside the tissue microenvironment. Our 3D-liver model has the potential to bridge the gap between animal models and the reality of the human host for the study of amoebic infection and other infectious diseases of the liver.
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Affiliation(s)
- Debora B Petropolis
- Institut Pasteur, Cell Biology and Infection Department, Cell Biology of Parasitism Unit, Paris, France; INSERM U786, Paris, France
| | - Daniela M Faust
- Institut Pasteur, Cell Biology and Infection Department, Cell Biology of Parasitism Unit, Paris, France; INSERM U786, Paris, France
| | - Gagan Deep Jhingan
- National Institute of Immunology, Signal Transduction Lab-1 Department, Aruna Asaf Ali Marg, New Delhi, India
| | - Nancy Guillen
- Institut Pasteur, Cell Biology and Infection Department, Cell Biology of Parasitism Unit, Paris, France; INSERM U786, Paris, France
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Loria P, Marchesini G, Nascimbeni F, Ballestri S, Maurantonio M, Carubbi F, Ratziu V, Lonardo A. Cardiovascular risk, lipidemic phenotype and steatosis. A comparative analysis of cirrhotic and non-cirrhotic liver disease due to varying etiology. Atherosclerosis 2014; 232:99-109. [PMID: 24401223 DOI: 10.1016/j.atherosclerosis.2013.10.030] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 10/23/2013] [Accepted: 10/24/2013] [Indexed: 02/08/2023]
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15
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Newer therapeutic strategies to alter high-density lipoprotein level and function. Cardiol Rev 2013; 22:17-24. [PMID: 23707991 DOI: 10.1097/crd.0b013e31829cac29] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Measurements of low levels of high-density lipoprotein (HDL) cholesterol have been identified as a risk factor for premature coronary artery disease, however, to date, current pharmacologic approaches for raising HDL have provided little benefit, if at all, in reducing cardiovascular outcomes. It has been shown that HDL can modify many aspects of plaque pathogenesis. Its most established role is in reverse cholesterol transportation, but HDL can also affect oxidation, inflammation, cellular adhesion, and vasodilatation. Considering these potential benefits of HDL, newer treatments have been developed to modify HDL activity, which include the use of oral cholesteryl ester transfer protein inhibitors, apolipoprotein (apo)A-I infusions, apoA-I mimetics, drugs to increase apoA-I synthesis, and agonists of the liver X receptor. These new therapies are reviewed in this article.
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The apolipoprotein m-sphingosine-1-phosphate axis: biological relevance in lipoprotein metabolism, lipid disorders and atherosclerosis. Int J Mol Sci 2013; 14:4419-31. [PMID: 23439550 PMCID: PMC3634416 DOI: 10.3390/ijms14034419] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 01/17/2013] [Accepted: 02/05/2013] [Indexed: 01/27/2023] Open
Abstract
Apolipoprotein M (apoM) is a plasma apolipoprotein that mainly associates with high-density lipoproteins. Hence, most studies on apoM so far have investigated its effect on and association with lipid metabolism and atherosclerosis. The insight into apoM biology recently took a major turn. ApoM was identified as a carrier of the bioactive lipid sphingosine-1-phosphate (S1P). S1P activates five different G-protein-coupled receptors, known as the S1P-receptors 1–5 and, hence, affects a wide range of biological processes, such as lymphocyte trafficking, angiogenesis, wound repair and even virus suppression and cancer. The ability of apoM to bind S1P is due to a lipophilic binding pocket within the lipocalin structure of the apoM molecule. Mice overexpressing apoM have increased plasma S1P concentrations, whereas apoM-deficient mice have decreased S1P levels. ApoM-S1P is able to activate the S1P-receptor-1, affecting the function of endothelial cells, and apoM-deficient mice display impaired endothelial permeability in the lung. This review will focus on the putative biological roles of the new apoM–S1P axis in relation to lipoprotein metabolism, lipid disorders and atherosclerosis.
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17
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Uccello M, Malaguarnera G, Pelligra EM, Biondi A, Basile F, Motta M. Lipoprotein(a) as a potential marker of residual liver function in hepatocellular carcinoma. Indian J Med Paediatr Oncol 2012; 32:71-5. [PMID: 22174493 PMCID: PMC3237183 DOI: 10.4103/0971-5851.89775] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The residual liver function is a major clinical index in hepatocellular carcinoma (HCC) patients. As the liver plays a crucial role in lipid and lipoprotein metabolism, the significant impairment of the hepatic function occurring during chronic liver diseases, such as HCC, can influence plasma lipoprotein profiles. Although, lipoprotein(a) (Lp(a)) circulating concentrations are mostly determined by genetic factors, in the majority of reports they have shown a correlation with the hepatic status and a significant decrease in HCC and liver cirrhosis patients than among the controls. In such a way, Lp(a) may represent a new additional and useful marker for a more complete assessment and monitoring of the liver function in patients with HCC and liver cirrhosis. Further studies are needed in order to evaluate the clinical significance of Lp(a) in HCC.
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Affiliation(s)
- Mario Uccello
- Departments of Senescence, Urological & Neurological Sciences, University of Catania, Catania, Italy
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18
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Abstract
Plasma levels of HDL (high-density lipoprotein)-cholesterol are strongly and inversely correlated with atherosclerotic cardiovascular disease. Both clinical and epidemiological studies have reported an inverse and independent association between serum HDL-cholesterol levels and CHD (coronary heart disease) risk. The cardioprotective effects of HDLs have been attributed to several mechanisms, including their involvement in the reverse cholesterol transport pathway. HDLs also have antioxidant, anti-inflammatory and antithrombotic properties and promote endothelial repair, all of which are likely to contribute to their ability to prevent CHD. The first part of this review summarizes what is known about the origins and metabolism of HDL. We then focus on the anti-inflammatory and antioxidant properties of HDL and discuss why these characteristics are cardioprotective.
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Miyazaki O, Fukamachi I, Mori A, Hashimoto H, Kawashiri MA, Nohara A, Noguchi T, Inazu A, Yamagishi M, Mabuchi H, Kobayashi J. Formation of prebeta1-HDL during lipolysis of triglyceride-rich lipoprotein. Biochem Biophys Res Commun 2008; 379:55-9. [PMID: 19070596 DOI: 10.1016/j.bbrc.2008.11.146] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2008] [Accepted: 11/30/2008] [Indexed: 10/21/2022]
Abstract
Prebeta1-HDL, a putative discoid-shaped high-density lipoprotein (HDL) is known to participate in the retrieval of cholesterol from peripheral tissues. In this study, to clarify potential sources of this lipoprotein, we conducted heparin injection on four Japanese volunteer men and found that serum triglyceride (TG) level decreased in parallel with the increase in serum nonesterified fatty acids and plasma lipoprotein lipase (LPL) protein mass after heparin injection. Plasma prebeta1-HDL showed considerable increases at 15 min after the heparin injection in all of the subjects. In contrast, serum HDL-C levels did not change. Gel filtration with fast protein liquid chromatography system (FPLC) study on lipoprotein profile revealed that in post-heparin plasma, low-density lipoprotein and alphaHDL fractions did not change, whereas there was a considerable decrease in very low-density lipoprotein (VLDL) fraction and an increase in prebeta1-HDL fraction when compared with those in pre-heparin plasma. We also conducted in vitro analysis on whether prebeta1-HDL was produced during VLDL lipolysis by LPL. One hundred microliters of VLDL extracted from pooled serum by ultracentrifugation was incubated with purified bovine milk LPL at 37 degrees C for 0-120 min. Prebeta1-HDL concentration increased in a dose dependent manner with increased concentration of added LPL in the reaction mixture and with increased incubation time, indicating that prebeta1-HDL was produced during lipolysis of VLDL by LPL. Taken these in vivo and in vitro analysis together, we suggest that lipolysis of VLDL particle by LPL is an important source for formation of prebeta1-HDL.
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Affiliation(s)
- Osamu Miyazaki
- Tsukuba Research Institute Research & Development Division, Sekisui Medical Co, Ltd, Ryugasaki, Japan
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20
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Mulya A, Lee JY, Gebre AK, Boudyguina EY, Chung SK, Smith TL, Colvin PL, Jiang XC, Parks JS. Initial interaction of apoA-I with ABCA1 impacts in vivo metabolic fate of nascent HDL. J Lipid Res 2008; 49:2390-401. [PMID: 18583707 DOI: 10.1194/jlr.m800241-jlr200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
We investigated the in vivo metabolic fate of pre-beta HDL particles in human apolipoprotein A-I transgenic (hA-I (Tg)) mice. Pre-beta HDL tracers were assembled by incubation of [(125)I]tyramine cellobiose-labeled apolipoprotein A-I (apoA-I) with HEK293 cells expressing ABCA1. Radiolabeled pre-beta HDLs of increasing size (pre-beta1, -2, -3, and -4 HDLs) were isolated by fast-protein liquid chromatography and injected into hA-I (Tg)-recipient mice, after which plasma decay, in vivo remodeling, and tissue uptake were monitored. Pre-beta2, -3, and -4 had similar plasma die-away rates, whereas pre-beta1 HDL was removed 7-fold more rapidly. Radiolabel recovered in liver and kidney 24 h after tracer injection suggested increased (P < 0.001) liver and decreased kidney catabolism as pre-beta HDL size increased. In plasma, pre-beta1 and -2 were rapidly (<5 min) remodeled into larger HDLs, whereas pre-beta3 and -4 were remodeled into smaller HDLs. Pre-beta HDLs were similarly remodeled in vitro with control or LCAT-immunodepleted plasma, but not when incubated with phospholipid transfer protein knockout plasma. Our results suggest that initial interaction of apoA-I with ABCA1 imparts a unique conformation that partially determines the in vivo metabolic fate of apoA-I, resulting in increased liver and decreased kidney catabolism as pre-beta HDL particle size increases.
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Affiliation(s)
- Anny Mulya
- Department of Pathology, Wake Forest University Health Sciences, Winston-Salem, NC, USA
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21
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Amigo L, Castro J, Miquel JF, Zanlungo S, Young S, Nervi F. Inactivation of hepatic microsomal triglyceride transfer protein protects mice from diet-induced gallstones. Gastroenterology 2006; 131:1870-8. [PMID: 17064699 DOI: 10.1053/j.gastro.2006.08.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2006] [Accepted: 07/26/2006] [Indexed: 12/23/2022]
Abstract
BACKGROUND & AIMS Microsomal triglyceride transfer protein (MTTP) is critical for the production of very-low-density lipoproteins (VLDL). The current studies were undertaken to examine the in vivo role of MTTP in hepatic cholesterol and fatty acid metabolism, as well as in biliary lipid secretion. We also tested whether MTTP plays a role in diet-induced cholelithiasis in mice. METHODS We used mice in which Mttp had been inactivated in the liver (Mttp(Delta/Delta) mice). We measured several parameters of cholesterol metabolism, fatty acid synthesis, and biliary lipid levels in mice fed a normal or a lithogenic diet. We also assessed the incidence of diet-associated gallstones. RESULTS Hepatic Mttp inactivation markedly decreased plasma triglyceride and cholesterol levels and increased biliary cholesterol and bile acid output. Hepatic cholesterogenesis and fatty acid synthesis were significantly decreased in Mttp(Delta/Delta) mice compared with control mice. The incidence of gallstones decreased from 90% in control mice to 33% in Mttp(Delta/Delta) mice after 8 weeks of a lithogenic diet (P < .0001). The mechanism of the protective effect appears to be increased biliary phospholipid output in Mttp(Delta/Delta) mice, leading to significant unsaturation of gallbladder bile. CONCLUSIONS These results indicate that modulation of Mttp expression in the liver affects hepatic lipid synthesis and storage as well as biliary lipid secretion. Our findings further indicate that inhibition of hepatic MTTP activity decreases the risk of experimental cholelithiasis by favoring phospholipid output into the bile.
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Affiliation(s)
- Ludwig Amigo
- Departamento de Gastroenterología, Facultad de Medicina Pontificia Universidad Católica, Santiago, Chile
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22
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Abstract
An inverse relationship between the concentration of high-density lipoprotein (HDL) cholesterol and the risk of developing cardiovascular is well established. There are several documented functions of HDLs that may contribute to a protective role of these lipoproteins. These include the ability of HDLs to promote the efflux of cholesterol from macrophages and foam cells in the artery wall and to anti-inflammatory/antioxidant properties of these lipoproteins. The fact that the main apolipoprotein of HDLs, apoA-I, plays a prominent role in each of these functions adds support to the view that apoA-I should be measured as a component of the assessment of cardiovascular risk in humans.
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Affiliation(s)
- P J Barter
- The Heart Research Institute, Sydney, Australia.
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23
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Fernandez ML, Metghalchi S, Vega-López S, Conde-Knape K, Lohman TG, Cordero-Macintyre ZR. Beneficial effects of weight loss on plasma apolipoproteins in postmenopausal women. J Nutr Biochem 2004; 15:717-21. [PMID: 15607644 DOI: 10.1016/j.jnutbio.2004.07.001] [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] [Indexed: 11/23/2022]
Abstract
A total of 39 postmenopausal women 40-70 years of age and undergoing hormone replacement therapy participated in a 6-month weight reduction program, which consisted of a low calorie diet (5040 KJ/day) and phentermine hydrochloride therapy. Subjects had an average body mass index of 35.95+/-5.32 kg/m(2) and 42.20+/-11.0 kg of total fat. Body mass index, plasma lipids, total and trunk fat, and plasma apoproteins were measured at baseline and after 3 and 6 months of the weight reduction program. Subjects experienced an overall 10% weight loss during the treatment period (P<0.001). Plasma LDL cholesterol and triglycerides were reduced by 18% and 15% (P<0.01) respectively, whereas HDL cholesterol was increased by 9% (P<0.01) over the 6-month period. Plasma apoproteins were significantly affected by weight loss. Plasma apolipoprotein (apo) B concentrations were reduced 6.5% (P<0.01), and apo C-III and apo E were reduced by 9% over 6 months (P<0.01). The observed decreases in plasma apo B were significantly correlated with the observed changes in plasma cholesterol (r=0.356, P<0.01) over 3 months. In addition, changes in plasma triglycerides were correlated with changes in both apo C-III (r=0.436) and apo E (r=0.354) over 6 months. These results suggest that weight loss may have multifactorial effects on lipoprotein metabolism, resulting in better plasma lipid and apoprotein profiles.
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Affiliation(s)
- Maria Luz Fernandez
- Department of Nutritional Sciences, University of Connecticut, 3624 Horsebarn Road Ext., Storrs, CT 06268, USA.
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24
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Rye KA, Barter PJ. Formation and Metabolism of Prebeta-Migrating, Lipid-Poor Apolipoprotein A-I. Arterioscler Thromb Vasc Biol 2004; 24:421-8. [PMID: 14592845 DOI: 10.1161/01.atv.0000104029.74961.f5] [Citation(s) in RCA: 236] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The preferred extracellular acceptor of cell phospholipids and unesterified cholesterol in the process mediated by the ATP-binding cassette A1 (ABCA1) transporter is a monomolecular, prebeta-migrating, lipid-poor or lipid-free form of apolipoprotein (apo) A-I. This monomolecular form of apoA-I is quite distinct from the prebeta-migrating, discoidal high-density lipoprotein (HDL) that contains two or three molecules of apoA-I per particle and which are present as minor components of the HDL fraction in human plasma. The mechanism of the ABCA1-mediated efflux of phospholipid and cholesterol from cells has been studied extensively. In contrast, much less attention has been given to the origin and subsequent metabolism of the acceptor lipid-free/lipid-poor apoA-I. There is a substantial body of evidence from studies conducted in vitro that a monomolecular, lipid-free/lipid-poor form of apoA-I dissociates from HDL during the remodeling of HDLs by plasma factors such as cholesteryl ester transfer protein, hepatic lipase, and phospholipid transfer protein. The rate at which apoA-I dissociates from HDL is influenced by the phospholipid composition of the particles and by the presence of apoA-II. This review describes current knowledge regarding the formation, metabolism, and regulation of monomolecular, lipid-free/lipid-poor apoA-I in plasma.
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Affiliation(s)
- Kerry-Anne Rye
- Heart Research Institute, Camperdown, Sydney, NSW, Australia
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25
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van Greevenbroek MMJ, Vermeulen VMMJ, de Bruin TWA. Familial combined hyperlipidemia plasma stimulates protein secretion by HepG2 cells: identification of fibronectin in the differential secretion proteome. J Lipid Res 2002; 43:1846-54. [PMID: 12401883 DOI: 10.1194/jlr.m100441-jlr200] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The aim of this study was to evaluate whether soluble factors in plasma of familial combined hyperlipidemia (FCHL) patients affect hepatic protein secretion. Cultured human hepatocytes, i.e., HepG2 cells, were incubated with fasting plasma (20%, v/v, in DMEM) from untreated FCHL patients or normolipidemic controls. Overall protein secretion was 10-15% higher after incubation with FCHL plasma. This was specifically caused by an increase in four secreted proteins, with estimated sizes of 240, 180, 120, and <40 kD (P < 0.001, P < 0.006, P < 0.002, P < 0.02, respectively). The 240 kD protein in the secretion proteome was identified as fibronectin by mass spectrometry. Plasma fibronectin concentrations were elevated in FCHL patients, confirming biological relevance of these data. Overall protein secretion by HepG2 cells correlated with concentrations of triglycerides (r = 0.61, P < 0.001) in the applied plasma samples. VLDL+IDL isolated from FCHL patients, induced a higher protein secretion than lipoproteins isolated from controls (P < 0.001). Remarkably, secretion of apoB, the structural protein of VLDL, was stimulated to a similar extent by FCHL and control plasma. FCHL plasma did not induce excess secretion of apoB by HepG2 cells compared with control plasma. FCHL plasma did stimulate secretion of several distinct hepatic proteins, among which fibronectin was identified.
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Chisholm JW, Burleson ER, Shelness GS, Parks JS. ApoA-I secretion from HepG2 cells: evidence for the secretion of both lipid-poor apoA-I and intracellularly assembled nascent HDL. J Lipid Res 2002. [DOI: 10.1016/s0022-2275(20)30184-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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Fuchs M, Hafer A, Münch C, Kannenberg F, Teichmann S, Scheibner J, Stange EF, Seedorf U. Disruption of the sterol carrier protein 2 gene in mice impairs biliary lipid and hepatic cholesterol metabolism. J Biol Chem 2001; 276:48058-65. [PMID: 11673458 DOI: 10.1074/jbc.m106732200] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Hepatic up-regulation of sterol carrier protein 2 (Scp2) in mice promotes hypersecretion of cholesterol into bile and gallstone formation in response to a lithogenic diet. We hypothesized that Scp2 deficiency may alter biliary lipid secretion and hepatic cholesterol metabolism. Male gallstone-susceptible C57BL/6 and C57BL/6(Scp2(-/-)) knockout mice were fed a standard chow or lithogenic diet. Hepatic biles were collected to determine biliary lipid secretion rates, bile flow, and bile salt pool size. Plasma lipoprotein distribution was investigated, and gene expression of cytosolic lipid-binding proteins, lipoprotein receptors, hepatic regulatory enzymes, and intestinal cholesterol absorption was measured. Compared with chow-fed wild-type animals, C57BL/6(Scp2(-/-)) mice had higher bile flow and lower bile salt secretion rates, decreased hepatic apolipoprotein expression, increased hepatic cholesterol synthesis, and up-regulation of liver fatty acid-binding protein. In addition, the bile salt pool size was reduced and intestinal cholesterol absorption was unaltered in C57BL/6(Scp2(-/-)) mice. When C57BL/6(Scp2(-/-)) mice were challenged with a lithogenic diet, a smaller increase of hepatic free cholesterol failed to suppress cholesterol synthesis and biliary cholesterol secretion increased to a much smaller extent than phospholipid and bile salt secretion. Scp2 deficiency did not prevent gallstone formation and may be compensated in part by hepatic up-regulation of liver fatty acid-binding protein. These results support a role of Scp2 in hepatic cholesterol metabolism, biliary lipid secretion, and intracellular cholesterol distribution.
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Affiliation(s)
- M Fuchs
- Division of Gastroenterology, Department of Medicine I, Medical University of Lübeck, D-23538 Lübeck, Germany.
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28
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Zanlungo S, Amigo L, Mendoza H, Miquel JF, Vío C, Glick JM, Rodríguez A, Kozarsky K, Quiñones V, Rigotti A, Nervi F. Sterol carrier protein 2 gene transfer changes lipid metabolism and enterohepatic sterol circulation in mice. Gastroenterology 2000; 119:1708-19. [PMID: 11113092 DOI: 10.1053/gast.2000.20198] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
BACKGROUND & AIMS Sterol carrier protein 2 (SCP-2) enhances sterol cycling and facilitates cholesterol translocation between intracellular organelles and plasma membrane in cultured cells, including hepatocytes. We examined the role of SCP-2 in hepatic cholesterol and lipid trafficking through the sinusoidal and canalicular secretory pathways of the liver in vivo. METHODS Recombinant adenovirus-mediated SCP-2 gene transfer was used to obtain hepatic overexpression of SCP-2 in C57BL/6 mice. RESULTS SCP-2 overexpression in the mouse liver resulted in an 8-fold increase of SCP-2 protein levels and determined various effects on lipid metabolism. It decreased high-density lipoprotein cholesterol and increased low-density lipoprotein (LDL) cholesterol concentrations. The expressions of hepatic LDL receptor, apolipoprotein (apo) A-I, apoB, and apoE were decreased. SCP-2 overexpression also increased hepatic cholesterol concentration, associated with decreased cholesterol neosynthesis. Increased biliary cholesterol and bile acid secretion, bile acid pool size, and intestinal cholesterol absorption were also observed. CONCLUSIONS These results indicate that modulation of SCP-2 expression in the liver determines important modifications on lipoprotein metabolism, hepatic cholesterol synthesis and storage, biliary lipid secretion, bile acid metabolism, and intestinal cholesterol absorption.
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Affiliation(s)
- S Zanlungo
- Departamento de Gastroenterología, Facultad de Medicina, Pontificia Universidad Católica, Santiago, Chile
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Levy E, Bendayan M. Use of immunoelectron microscopy and intestinal models to explore the elaboration of apolipoproteins required for intraenterocyte lipid transport. Microsc Res Tech 2000; 49:374-82. [PMID: 10820521 DOI: 10.1002/(sici)1097-0029(20000515)49:4<374::aid-jemt6>3.0.co;2-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The intestine is the organ that contributes the majority of circulating alimentary lipoproteins. Intestinal epithelial cells have the unique ability to elaborate chylomicrons, the largest triglyceride-rich lipoproteins and the main vehicle for the transport of dietary lipids. The final intracellular assembly and exocytosis of chylomicrons require enterocyte-derived apolipoproteins (apo). As research on lipoprotein metabolism evolved, it has become increasingly evident that apo B is a crucial protein for the normal packaging of triglyceride-rich lipoproteins. Immunocytochemical techniques have successfully been used to demonstrate the presence of two types of apo B, the B-100 and the B-48, in different subcellular compartments of the human enterocyte. Confirmation was obtained by biochemically analyzing human lymph and intestine from pediatric patients. In addition, the immunoelectron microscopic approach revealed the location of apo A-I in the rough endoplasmic reticulum (ER) and predominantly in the Golgi apparatus and the basolateral membrane, which confirms the rapid transport of apo A-I documented by other studies. Proven utility and experimental conditions were defined to demonstrate the ability of Caco-2 cells, a colon carcinoma cell line, to esterify lipids, synthesize apo, and assemble lipoproteins. Thus, immunocytochemical and biochemical techniques can be combined with in vivo and in vitro intestinal models for the study of the intestinal lipid transport.
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Affiliation(s)
- E Levy
- Hôpital Sainte-Justine Research Center, Montréal, Québec, Canada H3T 1C5
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30
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McConihay JA, Honkomp AM, Granholm NA, Woollett LA. Maternal high density lipoproteins affect fetal mass and extra-embryonic fetal tissue sterol metabolism in the mouse. J Lipid Res 2000. [DOI: 10.1016/s0022-2275(20)34481-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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31
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Abstract
Insulin gene therapy requires that insulin secretion be coupled to metabolic requirements. To this end, we have developed an insulin transgene whose transcription is stimulated by glucose and inhibited by insulin. Glucose- and insulin-sensitive promoters were constructed by inserting glucose-responsive elements (GlREs) from the rat L-pyruvate kinase (L-PK) gene into the insulin-sensitive, liver-specific, rat insulin-like growth factor binding protein-1 (IGFBP-1) promoter. Glucose (5 to 25 mM) stimulated, and insulin (10-10 to 10-7 M) inhibited, luciferase expression driven by these promoters in primary cultured rat hepatocytes. The capacity of transfected hepatocytes to secrete mature, biologically active insulin was demonstrated using a human proinsulin cDNA (2xfur), modified to allow protein processing by endogenous endopeptidase activity. Medium conditioned by insulin-producing hepatocytes contained greater than 300 microU/ml immunoreactive insulin, while denaturing SDS-PAGE of an anti-insulin immunoprecipitate revealed bands with the mobilities of insulin A, and B chains. Biological activity of hepatocyte-produced insulin was demonstrated in a transfection assay, in which medium conditioned by insulin-producing hepatocytes exerted an effect similar to 10-7 M insulin. We then combined the glucose- and insulin-sensitive promoter with the modified human proinsulin cDNA to create a metabolically sensitive insulin transgene ((GlRE)3BP-1 2xfur). In both H4IIE hepatoma cells stably transfected with this construct, and normal rat hepatocytes (GlRE)3BP-1 2xfur-mediated insulin secretion increased in response to stimulation by glucose. Moreover, a capacity to decrease insulin production in response to diminishing glucose exposure was also demonstrated. We conclude that the transcriptional regulation of insulin production using these glucose- and insulin-sensitive constructs meets the requirements for application in a rodent model of insulin gene therapy. Gene Therapy (2000) 7, 205-214.
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Affiliation(s)
- P M Thulé
- Veterans Administration Medical Center, Atlanta, GA, USA
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32
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Shen H, He L, Price RL, Fernandez ML. Dietary soluble fiber lowers plasma LDL cholesterol concentrations by altering lipoprotein metabolism in female guinea pigs. J Nutr 1998; 128:1434-41. [PMID: 9732302 DOI: 10.1093/jn/128.9.1434] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
This experiment was designed to evaluate the effects of pectin (PE), guar gum (GG) and psyllium (PSY) intake on VLDL and LDL metabolism in female guinea pigs fed high dietary cholesterol. Guinea pigs were fed a 15 g/100 g fat diet containing 0.25 g/100 g cholesterol with 12.5 g/100 g PE, 12.5 g/100 g GG, 7.5 g/100 g PSY or 12.5 g/100 g cellulose (control diet) for 4 wk. Plasma cholesterol concentrations were 29, 43 and 39% lower in guinea pigs fed PE, GG or PSY, respectively, compared with the control group (P < 0.0001). Plasma apolipoprotein (apo) B concentrations were 16-22% lower in the groups fed soluble fiber compared with the control group (P < 0.01). In contrast, hepatic cholesterol and triglyceride concentrations were not different among the PE, GG, PSY and control groups. No differences in triacylglycerol (TAG) or apo B secretion rates, measured by blocking VLDL catabolism by triton (WR 1339) injection, were observed, whereas plasma LDL apo B fractional catabolic rates (FCR), determined by injection of radiolabeled LDL, were higher in guinea pigs fed GG or PSY than in those from the control group. All sources of dietary soluble fiber reduced LDL apo B flux (P < 0.05). These results suggest that the mechanisms of plasma LDL cholesterol lowering by dietary soluble fiber are distinctive for each fiber source and result in specific alterations in lipoprotein metabolism in female guinea pigs. Differences between male and female guinea pigs in response to these diets are discussed.
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Affiliation(s)
- H Shen
- Lipid Metabolism Laboratory, Department of Nutritional Sciences, University of Arizona, Tucson, AZ 85721, USA
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33
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Sniderman AD, Zhang Z, Cianflone K. Divergent responses of the liver to increased delivery of glucose or fatty acids: implications for the pathogenesis of type IV hyperlipoproteinemia. Atherosclerosis 1998; 137:291-301. [PMID: 9622272 DOI: 10.1016/s0021-9150(97)00281-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
This study examines the patterns of response of primary cultures of hamster hepatocytes to increased delivery of glucose or oleate. Increased glucose in the medium produced: (1) increased triglyceride in the cells and the medium; (2) no change in cholesterol ester in the cells or the medium; (3) no change in apo B100 secreted into the medium; (4) more apo B100 particles within the VLDL range with an increase in the VLDL triglyceride to apo B100 ratio. By contrast, increased oleate in the medium resulted in: (1) increased triglyceride in the cells and the medium; (2) increased cholesterol ester in the cells and the medium; and (3) increased apo B100 secreted into the medium. Important differences in the intracellular metabolism of triglyceride and cholesterol ester were also documented. Under all circumstances, there was substantially more radiolabelled triglyceride (overall eight times more) in the cell than in the medium, indicating that up to 90% of the newly synthesized triglyceride enters the cellular pool rather than being secreted with apo B100. By contrast, almost half of the newly synthesized cholesterol ester molecules were secreted with apo B100, pointing to an equal probability of entering the cell storage pool as opposed to being secreted. The data establish therefore two patterns of response of the liver to increased triglyceride synthesis depending on whether the substrate drive is glucose or oleate.
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Affiliation(s)
- A D Sniderman
- Mike Rosenbloom Laboratory for Cardiovascular Research, Royal Victoria Hospital, Montreal, Canada
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34
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Sniderman AD, Cianflone K, Arner P, Summers LK, Frayn KN. The adipocyte, fatty acid trapping, and atherogenesis. Arterioscler Thromb Vasc Biol 1998; 18:147-51. [PMID: 9484977 DOI: 10.1161/01.atv.18.2.147] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- A D Sniderman
- Mike Rosenbloom Laboratory for Cardiovascular Research, McGill University, Montreal, Quebec, Canada.
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35
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Riddell D, Bright CP, Burton BJ, Bush RC, Harris NV, Hele D, Moore UM, Naik K, Parrott DP, Smith C, Williams RJ. Hypolipidaemic properties of a potent and bioavailable alkylsulphinyl-diphenylimidazole ACAT inhibitor (RP 73163) in animals fed diets low in cholesterol. Biochem Pharmacol 1996; 52:1177-86. [PMID: 8937424 DOI: 10.1016/0006-2952(96)00455-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
RP 73163 ((S)-2-[5-(3,5-dimethyl-l-pyrazolyl)pent-l-yl)-sulphinyl]-5, 6-diphenylimidazole) has been shown to be a potent and specific inhibitor of acyl-CoA:cholesterol acyltransferase (EC 2.3.1.26; ACAT) in vitro using the tissues of experimental animals as sources of the enzyme. The concentrations of RP 73163 required to produce 50% inhibition of ACAT activity (IC50 values) in microsomal preparations ranged from 86 nM for rat liver to 370 nM for rabbit intestine. In whole cell assays using human hepatic (HepG2), intestinal (Caco2), and monocytic (THP-1) cell lines, RP 73163 inhibited ACAT activity with IC50 values of 266, 158, and 314 nM, respectively. The addition of RP 73163 (0.03-1.0 microM) to the medium of cultured HepG2 cells produced a concentration-dependent decrease in apolipoprotein B (apoB) secretion. The compound has high systemic bioavailability. Using a bioassay, a concentration of active inhibitor equivalent to 29 microM of parent compound was present in plasma 1 hr after oral administration of RP 73163 (50 mg.kg-1). In rats that had been fed a basal diet ad libitum or starved for 18 hr prior to blood sampling, the administration of RP 73163 (50 mg.kg-1 b.i.d. for 7 days) reduced plasma triglyceride levels by 50% without affecting the concentration of cholesterol. This hypotriglyceridaemic effect was associated with reductions in plasma very-low-density-lipoprotein (VLDL) and low-density-lipoprotein (LDL) levels. RP 73163 decreased the rate of VLDL secretion by 24% in Triton WR-1339-treated rats that had been fasted overnight but did not affect the secretion rate in animals fed ad libitum, indicating that ACAT was only important in regulating VLDL secretion under certain nutritional conditions. RP 73163 reduced the accumulation of intraperitoneally administered [3H]leucine into the plasma VLDL-apoB pool in both fed and fasted states. The results suggest that, in fed animals at least, an increase in the clearance of VLDL from the bloodstream may contribute to the hypolipidaemic activity of the compound. In rabbits with casein-induced endogenous hypercholesterolaemia, RP 73163 specifically reduced the levels of cholesterol carried by LDL. In conclusion, the hypolipidaemic actions of RP 73163, a potent and systemically bioavailable ACAT inhibitor, are consistent with a reduction in the secretion of apoB containing lipoproteins by hepatic tissue and possibly with an increase in the clearance of these particles.
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Affiliation(s)
- D Riddell
- Rhône-Poulenc Rorer Lt., Dagenham Research Centre, Essex, U.K
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36
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Nassir F, Mazur A, Giannoni F, Gueux E, Davidson NO, Rayssiguier Y. Magnesium deficiency modulates hepatic lipogenesis and apolipoprotein gene expression in the rat. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1257:125-32. [PMID: 7619852 DOI: 10.1016/0005-2760(95)00065-k] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The present study was performed to determine the effects of magnesium (Mg) deficiency upon plasma lipoproteins and hepatic apolipoprotein gene expression in the rat. The most obvious effect of Mg-deficiency on plasma lipids is a marked increase in post-prandial triacylglycerol concentration. This increased triglyceridemia persists in fasted rats. Density gradient ultracentrifugation analysis revealed marked alterations in the distribution of plasma lipoproteins in Mg-deficient rats. An increase in triacylglycerol-rich lipoproteins (TGRLP) was associated with a significant increase in plasma apolipoprotein B (apo B) concentration and was accompanied by selective accumulation of apo B-48. A decrease in high-density lipoproteins (HDL) was accompanied by a corresponding decrease in plasma apo E concentration and a concordant decrease in hepatic apo E mRNA abundance and biosynthesis. Hepatic apo B-100 synthesis was reduced by over 75% in Mg-deficient animals despite an increase in hepatic apo B mRNA abundance. However, this change in hepatic apo B gene expression was not associated with alterations in posttranscriptional apo B mRNA editing. These changes in apolipoprotein gene expression were associated with increased hepatic lipogenesis, despite the observation that net triacylglycerol secretion rates were not different between Mg-deficient and control animals. Taken together, the data demonstrate a complex pattern of alterations in hepatic lipid metabolism and apolipoprotein gene expression in the Mg-deficient rat and suggest a defect in the catabolism rather than secretion of TGLRP as the major factor underlying the altered plasma lipoprotein profile.
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Affiliation(s)
- F Nassir
- Laboratoire des Maladies Métaboliques, INRA, France
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37
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Sparks JD, Sparks CE. Insulin regulation of triacylglycerol-rich lipoprotein synthesis and secretion. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1215:9-32. [PMID: 7948013 DOI: 10.1016/0005-2760(94)90088-4] [Citation(s) in RCA: 154] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
This review has considered a number of observations obtained from studies of insulin in perfused liver, hepatocytes, transformed liver cells and in vivo and each of the experimental systems offers advantages. The evaluation of insulin effects on component lipid synthesis suggests that overall, lipid synthesis is positively influenced by insulin. Short-term high levels of insulin through stimulation of intracellular degradation of freshly translated apo B and effects on synthesis limit the ability of hepatocytes to form and secrete TRL. The intracellular site of apo B degradation may involve membrane-bound apo B, cytoplasmic apo B and apo B which has entered the ER lumen. How insulin favors intracellular apo B degradation is not known. An area of recent investigation is in insulin-stimulated phosphorylation of intracellular substrates such as IRS-1 which activates insulin specific cellular signaling molecules [245]. Candidate molecules to study insulin action on apo B include IRS-1 and SH2-containing signaling molecules. Insulin dysregulation in carbohydrate metabolism occurs in non-insulin-dependent diabetes mellitus due to an imbalance between insulin sensitivity of tissue and pancreatic insulin secretion (reviewed in Refs. [307,308]). Insulin resistance in the liver results in the inability to suppress hepatic glucose production; in muscle, in impaired glucose uptake and oxidation and in adipose tissue, in the inability to suppress release of free FA. This lack of appropriate sensitivity towards insulin action leads to hyperglycemia which in turn stimulates compensatory insulin secretion by the pancreas leading to hyperinsulinemia. Ultimately, there may be failure of the pancreas to fully compensate, hyperglycemia worsens and diabetes develops. The etiology of insulin resistance is being intensively studied for the primary defect may be over secretion of insulin by the pancreas or tissue insulin resistance and both of these defects may be genetically predetermined. We suggest that, in addition to effects in carbohydrate metabolism, insulin resistance in liver results in the inability of first phase insulin to suppress hepatic TRL production which results in hypertriglyceridemia leading to high levels of plasma FA which accentuate insulin resistance in other target organs. As recently reviewed [17,254] the role of insulin as a stimulator of hepatic lipogenesis and TRL production has been long established. Several lines of evidence support that insulin is stimulatory to the production of hepatic TRL in vivo. First, population based studies support a positive relationship between plasma insulin and total TG and VLDL [253]. Second, there is a strong association between chronic hyperinsulinemia and VLDL overproduction [309].(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- J D Sparks
- Department of Pathology, University of Rochester, School of Medicine and Dentistry, NY 14642
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38
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Cianflone K, Vu H, Zhang Z, Sniderman AD. Effects of albumin on lipid synthesis, apo B-100 secretion, and LDL catabolism in HepG2 cells. Atherosclerosis 1994; 107:125-35. [PMID: 7980689 DOI: 10.1016/0021-9150(94)90014-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
This study examines the effects of extracellular albumin on hepatic apo B-100 metabolism. To do so, a transformed human liver cell line, HepG2, was used as a hepatocyte model and the concentration of albumin in the medium was varied between 0 and 5 g%. Apo B-100 and apo A1 concentrations in the medium were determined by specific enzyme-linked immunoassay (ELISA) and intracellular synthesis of cholesterol ester and triglyceride were determined by addition of appropriate radiolabels to the medium. The data demonstrate that the reduction of extracellular albumin concentration resulted in increased apo B-100 concentration in the medium. Apo A1 secretion, however, was unaffected. While the differences in apo B-100 concentration in the medium were statistically significant (33% +/- 7%, P < 0.0025, 0 g% albumin compared to 5 g% albumin in the medium), the absolute magnitude of the effect under these conditions was relatively modest. Nevertheless, the changes were consistent and evident over incubation periods as long as 8 days. Of interest, although triglyceride synthesis was unaffected, cholesterol ester synthesis changed such that as albumin concentration decreased, synthesis of cholesterol ester increased paralleling the changes in apo B-100 (170% +/- 9%, P < 0.005). These findings were extended by studying interventions which altered cholesterol ester synthesis. Addition of the compound 58-035 (5 micrograms/ml, a specific inhibitor of acylcholesterol acyltransferase activity) resulted in substantial inhibition of cholesterol ester synthesis (39% to 66%, P < 0.025 and P < 0.005, respectively) and apo B-100 concentrations in the medium which decreased by 20% to 28%, P < 0.025. Triglyceride synthesis, in contrast, increased significantly by 32% P < 0.025. Therefore, addition of 58-035 confirmed the previous findings of a parallel relation between cholesterol ester synthesis and apo B-100 concentration in the medium. Nonetheless, albumin still had an additional inhibitory effect on cholesterol ester and apo B-100 secretion. Of interest, when chylomicron remnants (25 micrograms/ml cholesterol), which cause apo B-100 secretion to increase by more than threefold, were added to the medium, albumin now had a more pronounced absolute effect on apo B-100 secretion with a 48% inhibition observed as albumin was increased from 0 to 5 g% in the medium (P < 0.0125). The effect of extracellular albumin on the low density lipoprotein (LDL) pathway was also examined. No differences in non-specific cell association component were detected.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- K Cianflone
- McGill Unit for the Prevention of Cardiovascular Disease, Royal Victoria Hospital, Montreal, Canada
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