1
|
Kasano-Camones CI, Takizawa M, Ohshima N, Saito C, Iwasaki W, Nakagawa Y, Fujitani Y, Yoshida R, Saito Y, Izumi T, Terawaki SI, Sakaguchi M, Gonzalez FJ, Inoue Y. PPARα activation partially drives NAFLD development in liver-specific Hnf4a-null mice. J Biochem 2023; 173:393-411. [PMID: 36779417 PMCID: PMC10433406 DOI: 10.1093/jb/mvad005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 01/13/2023] [Indexed: 01/24/2023] Open
Abstract
HNF4α regulates various genes to maintain liver function. There have been reports linking HNF4α expression to the development of non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis. In this study, liver-specific Hnf4a-deficient mice (Hnf4aΔHep mice) developed hepatosteatosis and liver fibrosis, and they were found to have difficulty utilizing glucose. In Hnf4aΔHep mice, the expression of fatty acid oxidation-related genes, which are PPARα target genes, was increased in contrast to the decreased expression of PPARα, suggesting that Hnf4aΔHep mice take up more lipids in the liver instead of glucose. Furthermore, Hnf4aΔHep/Ppara-/- mice, which are simultaneously deficient in HNF4α and PPARα, showed improved hepatosteatosis and fibrosis. Increased C18:1 and C18:1/C18:0 ratio was observed in the livers of Hnf4aΔHep mice, and the transactivation of PPARα target gene was induced by C18:1. When the C18:1/C18:0 ratio was close to that of Hnf4aΔHep mouse liver, a significant increase in transactivation was observed. In addition, the expression of Pgc1a, a coactivator of PPARs, was increased, suggesting that elevated C18:1 and Pgc1a expression could contribute to PPARα activation in Hnf4aΔHep mice. These insights may contribute to the development of new diagnostic and therapeutic approaches for NAFLD by focusing on the HNF4α and PPARα signaling cascade.
Collapse
Affiliation(s)
- Carlos Ichiro Kasano-Camones
- Laboratory of Metabolism, Division of Molecular Science, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma 376-8515, Japan
| | - Masayuki Takizawa
- Laboratory of Metabolism, Division of Molecular Science, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma 376-8515, Japan
| | - Noriyasu Ohshima
- Department of Biochemistry, Graduate School of Medicine, Gunma University, Maebashi 371-8511, Japan
| | - Chinatsu Saito
- Laboratory of Metabolism, Division of Molecular Science, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma 376-8515, Japan
| | - Wakana Iwasaki
- Laboratory of Metabolism, Division of Molecular Science, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma 376-8515, Japan
| | - Yuko Nakagawa
- Laboratory of Developmental Biology and Metabolism, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
| | - Yoshio Fujitani
- Laboratory of Developmental Biology and Metabolism, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
| | - Ryo Yoshida
- Laboratory of Metabolism, Division of Molecular Science, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma 376-8515, Japan
| | - Yoshifumi Saito
- Laboratory of Metabolism, Division of Molecular Science, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma 376-8515, Japan
| | - Takashi Izumi
- Department of Biochemistry, Graduate School of Medicine, Gunma University, Maebashi 371-8511, Japan
- Faculty of Health Care, Teikyo Heisei University, Tokyo 170-8445, Japan
| | - Shin-Ichi Terawaki
- Laboratory of Metabolism, Division of Molecular Science, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma 376-8515, Japan
| | - Masakiyo Sakaguchi
- Department of Cell Biology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
| | - Frank J Gonzalez
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20852, USA
| | - Yusuke Inoue
- Laboratory of Metabolism, Division of Molecular Science, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma 376-8515, Japan
- Gunma University Center for Food Science and Wellness, Maebashi, Gunma 371-8510, Japan
| |
Collapse
|
2
|
Li P, Chen X, Dong M, Luo J, Lu S, Chen M, Zhang Y, Zhou H, Jiang H. Gut inflammation exacerbates high-fat diet induced steatosis by suppressing VLDL-TG secretion through HNF4α pathway. Free Radic Biol Med 2021; 172:459-469. [PMID: 34186207 DOI: 10.1016/j.freeradbiomed.2021.06.027] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 06/20/2021] [Accepted: 06/23/2021] [Indexed: 12/11/2022]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is increasingly identified in inflammatory bowel disease (IBD) patients with unclear etiology. In the current study we assessed the contribution of colonic inflammation to NAFLD development and the underlying mechanism in a mouse model for IBD. Our results showed that dextran sulfate sodium (DSS)-induced gut colitis directly led to hepatic inflammation, injury and further exacerbated hepatic steatosis caused by high fat diet (HF) feeding. The essential genes assessment, hepatic metabolic analysis and triglyceride-rich very low-density lipoprotein (VLDL-TG) secretion assays revealed a higher β-oxidation of fatty acids (FAs) but impaired VLDL-TG secretion in liver of DSS-treated mice. Disruption of the intestinal barrier by DSS promoted liver inflammation, which strongly suppressed hepatic VLDL-TG secretion and further aggravated HF-induced VLDL-TG secretion impairment through down-regulation of apolipoprotein B (APOB), hence promoting the storage of triglycerides (TG) in the liver. Inflammation induced by mixed proinflammatory cytokines or LPS obviously inhibited the expression of microsomal triglyceride transfer protein (MTP) and APOB expression and subsequently increased TG content via the suppression of HNF4α in mouse primary hepatocytes. In addition, the downregulation of MTP and APOB by proinflammatory cytokines was also rescued through activating Hnf4α by cortisol. Altogether, our results demonstrated that chronic inflammation exacerbated hepatic steatosis by inhibiting the secreting of hepatic VLDL-TG through HNF4α pathway, suggesting that restoring hepatic VLDL-TG secretion may be a novel strategy for treatment of NAFLD in IBD.
Collapse
Affiliation(s)
- Ping Li
- Laboratory of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Xiu Chen
- Laboratory of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Minlei Dong
- Laboratory of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Jun Luo
- Laboratory of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Shuanghui Lu
- Laboratory of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Mingyang Chen
- Laboratory of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Yingqiong Zhang
- Laboratory of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Hui Zhou
- Laboratory of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Huidi Jiang
- Laboratory of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China.
| |
Collapse
|
3
|
Fang W, Chen Q, Cui K, Chen Q, Li X, Xu N, Mai K, Ai Q. Lipid overload impairs hepatic VLDL secretion via oxidative stress-mediated PKCδ-HNF4α-MTP pathway in large yellow croaker (Larimichthys crocea). Free Radic Biol Med 2021; 172:213-225. [PMID: 34116177 DOI: 10.1016/j.freeradbiomed.2021.06.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 05/30/2021] [Accepted: 06/02/2021] [Indexed: 02/08/2023]
Abstract
Lipid overload-induced hepatic steatosis is a major public health problem worldwide. However, the potential molecular mechanism is not completely understood. Herein, we found that high-fat diet (HFD) or oleic acid (OA) treatment induced oxidative stress which prevented the entry of hepatocyte nuclear factor 4 alpha (HNF4α) into the nucleus by activating protein kinase C delta (PKCδ) in vivo and in vitro in large yellow croaker (Larimichthys crocea). This reduced the level of microsomal triglyceride transfer protein (MTP) transcription, resulting in the impaired secretion of very-low-density lipoprotein (VLDL) and the abnormal accumulation of triglyceride (TG) in hepatocytes. Meanwhile, the detrimental effects induced by lipid overload could be partly alleviated by pretreating hepatocytes with Go6983 (PKCδ inhibitor) or N-acetylcysteine (NAC, reactive oxygen species (ROS) scavenger). In conclusion, for the first time, we revealed that lipid overload impaired hepatic VLDL secretion via oxidative stress-mediated PKCδ-HNF4α-MTP pathway in fish. This study may provide critical insights into potential intervention strategies against lipid overload-induced hepatic steatosis of fish and human beings.
Collapse
Affiliation(s)
- Wei Fang
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) and Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, People's Republic of China
| | - Qiuchi Chen
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) and Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, People's Republic of China
| | - Kun Cui
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) and Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, People's Republic of China
| | - Qiang Chen
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) and Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, People's Republic of China
| | - Xueshan Li
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) and Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, People's Republic of China
| | - Ning Xu
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) and Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, People's Republic of China
| | - Kangsen Mai
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) and Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, People's Republic of China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, 1 Wenhai Road, 266237, Qingdao, Shandong, People's Republic of China
| | - Qinghui Ai
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) and Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, 266003, Qingdao, Shandong, People's Republic of China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, 1 Wenhai Road, 266237, Qingdao, Shandong, People's Republic of China.
| |
Collapse
|
4
|
Kuefner MS. Secretory Phospholipase A2s in Insulin Resistance and Metabolism. Front Endocrinol (Lausanne) 2021; 12:732726. [PMID: 34512555 PMCID: PMC8429832 DOI: 10.3389/fendo.2021.732726] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 08/09/2021] [Indexed: 01/01/2023] Open
Abstract
The phospholipases A2 (PLA2) superfamily encompasses enzymes commonly found in mammalian tissues and snake venom. Many of these enzymes have unique tissue distribution, function, and substrate specificity suggesting distinct biological roles. In the past, much of the research on secretory PLA2s has analyzed their roles in inflammation, anti-bacterial actions, and atherosclerosis. In recent studies utilizing a variety of mouse models, pancreatic islets, and clinical trials, a role for many of these enzymes in the control of metabolism and insulin action has been revealed. In this review, this research, and the unique contributions of the PLA2 enzymes in insulin resistance and metabolism.
Collapse
|
5
|
Tan SY, Little HC, Sarver DC, Watkins PA, Wong GW. CTRP12 inhibits triglyceride synthesis and export in hepatocytes by suppressing HNF-4α and DGAT2 expression. FEBS Lett 2020; 594:3227-3239. [PMID: 32749667 DOI: 10.1002/1873-3468.13895] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 07/21/2020] [Accepted: 07/25/2020] [Indexed: 12/15/2022]
Abstract
C1q/TNF-related protein 12 (CTRP12) is an antidiabetic adipokine whose circulating levels are reduced in obesity and diabetes. Although partial and complete loss-of-function mouse models suggest a role for CTRP12 in modulating lipid metabolism and adiposity, its effect on cellular lipid metabolism remains poorly defined. Here, we demonstrate a direct action of CTRP12 in regulating lipid synthesis and secretion. In hepatoma cells and primary mouse hepatocytes, CTRP12 treatment inhibits triglyceride synthesis by suppressing glycerophosphate acyltransferase (GPAT) and diacylglycerol acyltransferase (DGAT) expression. CTRP12 treatment also downregulates the expression of hepatocyte nuclear factor-4α (HNF-4α) and its target gene microsomal triglyceride transfer protein (MTTP), leading to reduced very-low-density lipoprotein (VLDL)-triglyceride export from hepatocytes. Consistent with the in vitro findings, overexpressing CTRP12 lowers fasting and postprandial serum triglyceride levels in mice. These results underscore the important function of CTRP12 in lipid metabolism in hepatocytes.
Collapse
Affiliation(s)
- Stefanie Y Tan
- Department of Physiology and Center for Metabolism and Obesity Research, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Pfizer, 1 Portland St., Cambridge, MA, 02139, USA
| | - Hannah C Little
- Department of Physiology and Center for Metabolism and Obesity Research, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Dylan C Sarver
- Department of Physiology and Center for Metabolism and Obesity Research, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Paul A Watkins
- Department of Neurology and Biological Chemistry, Johns Hopkins University School of Medicine, and Hugo W. Moser Research Institute at Kennedy Krieger, Baltimore, MD, USA
| | - G William Wong
- Department of Physiology and Center for Metabolism and Obesity Research, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| |
Collapse
|
6
|
Zhang M, Yang M, Wang N, Liu Q, Wang B, Huang T, Tong Y, Ming Y, Wong CW, Liu J, Yao D, Guan M. Andrographolide modulates HNF4α activity imparting on hepatic metabolism. Mol Cell Endocrinol 2020; 513:110867. [PMID: 32422400 DOI: 10.1016/j.mce.2020.110867] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 05/09/2020] [Accepted: 05/10/2020] [Indexed: 12/28/2022]
Abstract
Hepatic nuclear factor 4 alpha (HNF4α) drives the expression of apolipoprotein B (ApoB), microsomal triglyceride transfer protein (MTP) and phospholipase A2 G12B (PLA2G12B), governing hepatic very-low-density lipoprotein (VLDL) production and secretion. Andrographolide (AP) is a major constituent isolated from Andrographis paniculata. We found that AP can disrupt the interaction between HNF4α and its coactivator peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α). Virtual docking and mutational analysis indicated that arginine 235 of HNF4α is essential for binding to AP. As a consequence of antagonizing the activity of HNF4α, AP suppresses the expression of ApoB, MTP and PLA2G12B and reduces the rate of hepatic VLDL secretion in vivo. AP additionally reduced gluconeogenesis via down-regulating the expression of HNF4α target genes phosphoenolpyruvate carboxykinase (Pepck) and glucose-6-phosphatase (G6pc). Collectively, our results suggest that AP affects liver function via modulating the transcriptional activity of HNF4α.
Collapse
Affiliation(s)
- Minyi Zhang
- National Engineering Research Center of Genetic Medicine, Institute of Biomedicine, Jinan University, Guangzhou, 510632, Guangdong, China; Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, Guangdong, China
| | - Meng Yang
- Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, Guangdong, China
| | - Na Wang
- Guangdong Provincial Key Laboratory of Biocomputing, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, 510530, China
| | - Qingli Liu
- Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, Guangdong, China
| | - Binxu Wang
- Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, Guangdong, China
| | - Tongling Huang
- Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, Guangdong, China
| | - Yan Tong
- Institute of Chemical Engineering, Huaqiao University, Xiamen, Fujian, 361021, China
| | - Yanlin Ming
- Institute of Chemical Engineering, Huaqiao University, Xiamen, Fujian, 361021, China
| | - Chi-Wai Wong
- NeuMed Pharmaceuticals Limited, Yuen Long, Hong Kong, China
| | - Jinsong Liu
- Guangdong Provincial Key Laboratory of Biocomputing, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, 510530, China
| | - Dongsheng Yao
- National Engineering Research Center of Genetic Medicine, Institute of Biomedicine, Jinan University, Guangzhou, 510632, Guangdong, China.
| | - Min Guan
- Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, Guangdong, China.
| |
Collapse
|
7
|
Migliaccio S, Brasacchio C, Pivari F, Salzano C, Barrea L, Muscogiuri G, Savastano S, Colao A. What is the best diet for cardiovascular wellness? A comparison of different nutritional models. INTERNATIONAL JOURNAL OF OBESITY SUPPLEMENTS 2020; 10:50-61. [PMID: 32714512 PMCID: PMC7371887 DOI: 10.1038/s41367-020-0018-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Cardiovascular diseases (CVD) represent to date the leading cause of mortality in both genders in the developed countries. In this context, a strong need for CVD prevention is emerging through lifestyle modification and nutrition. In fact, several studies linked CVD with unhealthy nutrition, alcohol consumption, stress, and smoking, together with a low level of physical activity. Thus, the primary aim is to prevent and reduce CVD risk factors, such as impaired lipid and glycemic profiles, high blood pressure and obesity. Different types of diet have been, therefore, established to optimize the approach regarding this issue such as the Mediterranean diet, Dietary Approaches to Stop Hypertension diet (DASH), vegetarian diet, ketogenic diet, and Japanese diet. Depending on the diet type, recommendations generally emphasize subjects to increase vegetables, fruits, whole grains, and pulses consumption, but discourage or recommend eliminating red meat, sweets, and sugar-sweetened beverages, along with processed foods that are high in sugar, salt, fat, or low in dietary fiber. In particular, we evaluated and compared the peculiar aspects of these well-known dietary patterns and, thus, this review evaluates the critical factors that increase CVD risk and the potential application and benefits of nutritional protocols to ameliorate dietary and lifestyle patterns for CVD prevention.
Collapse
Affiliation(s)
- Silvia Migliaccio
- Department of Movement, Human and Health Sciences, Health Sciences Section, University “Foro Italico”, Rome, Italy
| | | | - Francesca Pivari
- Department of Health Sciences, University of Milan, Milan, Italy
| | - Ciro Salzano
- Dipartimento di Medicina Clinica e Chirurgia, Unit of Endocrinology, Federico II University Medical School of Naples, Via Sergio Pansini 5, 80131 Naples, Italy
| | - Luigi Barrea
- Dipartimento di Medicina Clinica e Chirurgia, Unit of Endocrinology, Federico II University Medical School of Naples, Via Sergio Pansini 5, 80131 Naples, Italy
| | - Giovanna Muscogiuri
- Dipartimento di Medicina Clinica e Chirurgia, Unit of Endocrinology, Federico II University Medical School of Naples, Via Sergio Pansini 5, 80131 Naples, Italy
| | - Silvia Savastano
- Dipartimento di Medicina Clinica e Chirurgia, Unit of Endocrinology, Federico II University Medical School of Naples, Via Sergio Pansini 5, 80131 Naples, Italy
| | - Annamaria Colao
- Dipartimento di Medicina Clinica e Chirurgia, Unit of Endocrinology, Federico II University Medical School of Naples, Via Sergio Pansini 5, 80131 Naples, Italy
| | - on behalf of Obesity Programs of nutrition, Education, Research and Assessment (OPERA) Group
- Department of Movement, Human and Health Sciences, Health Sciences Section, University “Foro Italico”, Rome, Italy
- Department of Health Sciences, University of Milan, Milan, Italy
- Dipartimento di Medicina Clinica e Chirurgia, Unit of Endocrinology, Federico II University Medical School of Naples, Via Sergio Pansini 5, 80131 Naples, Italy
| |
Collapse
|
8
|
Wu H, Xu L, Ballantyne CM. Dietary and Pharmacological Fatty Acids and Cardiovascular Health. J Clin Endocrinol Metab 2020; 105:5611200. [PMID: 31678992 PMCID: PMC7174038 DOI: 10.1210/clinem/dgz174] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 11/01/2019] [Indexed: 12/30/2022]
Abstract
CONTEXT The effects of dietary intake of different fatty acids and pharmacological use of fatty acids, specifically long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFAs), on cardiovascular health and atherosclerotic cardiovascular disease (ASCVD) prevention have been examined in a large number of observational studies and clinical trials. This review summarizes recent data and discusses potential mechanisms. EVIDENCE ACQUISITION The review is based on the authors' knowledge of the field supplemented by a PubMed search using the terms seafood, fish oil, saturated fatty acids, omega-3 fatty acids, eicosapentaenoic acid, docosahexaenoic acid, polyunsaturated fatty acids, monounsaturated fatty acids, and ASCVD. EVIDENCE SYNTHESIS We mainly discuss the recent clinical trials that examine the effects of different types of dietary fatty acids and pharmacological use of n-3 PUFA products on ASCVD prevention and the potential mechanisms. CONCLUSIONS While replacement of dietary saturated fat with unsaturated fat, polyunsaturated fat in particular, or intake of LC n-3 PUFA-rich seafood has generally shown benefit for ASCVD prevention and is recommended for cardiovascular benefits, data on effects of n-3 PUFA products on ASCVD health are inconsistent. However, recent clinical trials support benefits of prescription EPA in ASCVD prevention. n-3 PUFAs may contribute to ASCVD prevention through multiple mechanisms, including lowering plasma triglyceride levels, anti-inflammatory effects, antithrombotic effects, and effects on endothelial function.
Collapse
Affiliation(s)
- Huaizhu Wu
- Department of Medicine, Baylor College of Medicine, Houston, Texas
| | - Lu Xu
- Department of Medicine, Baylor College of Medicine, Houston, Texas
| | - Christie M Ballantyne
- Department of Medicine, Baylor College of Medicine, Houston, Texas
- Correspondence: Christie M. Ballantyne, MD, Baylor College of Medicine, One Baylor Plaza, MS BCM285, Houston, TX 77030. E-mail:
| |
Collapse
|
9
|
Hatchwell L, Harney DJ, Cielesh M, Young K, Koay YC, O’Sullivan JF, Larance M. Multi-omics Analysis of the Intermittent Fasting Response in Mice Identifies an Unexpected Role for HNF4α. Cell Rep 2020; 30:3566-3582.e4. [DOI: 10.1016/j.celrep.2020.02.051] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 01/24/2020] [Accepted: 02/11/2020] [Indexed: 12/21/2022] Open
|
10
|
Feng J, Yang J, Chang Y, Qiao L, Dang H, Luo K, Guo H, An Y, Ma C, Shao H, Tian J, Yuan Y, Xie L, Xing W, Cheng J. Caffeine-free hawk tea lowers cholesterol by reducing free cholesterol uptake and the production of very-low-density lipoprotein. Commun Biol 2019; 2:173. [PMID: 31098406 PMCID: PMC6506518 DOI: 10.1038/s42003-019-0396-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 03/21/2019] [Indexed: 02/08/2023] Open
Abstract
Medicinal plants show important therapeutic value in chronic disease treatment. However, due to their diverse ingredients and complex biological effects, the molecular mechanisms of medicinal plants are yet to be explored. By means of several high-throughput platforms, here we show hawk tea extract (HTE) inhibits Niemann-Pick C1-like 1 (NPC1L1)-mediated free cholesterol uptake, thereby inducing the transcription of low-density lipoprotein receptor (LDLR) downstream of the sterol response element binding protein 2 (SREBP2) pathway. Meanwhile, HTE suppresses hepatocyte nuclear factor 4α (HNF4α)-mediated transcription of microsomal triglyceride transfer protein (MTP) and apolipoprotein B (APOB), thereby decreasing the production of very-low-density lipoprotein. The catechin EGCG ((-)-epigallocatechin gallate) and the flavonoids kaempferol and quercetin are identified as the bioactive components responsible for the effects on the NPC1L1-SREBP2-LDLR axis and HNF4α-MTP/APOB axis, respectively. Overall, hawk tea works as a previously unrecognized cholesterol-lowering agent in a multi-target and multi-component manner.
Collapse
Affiliation(s)
- Juan Feng
- State Key Laboratory of Membrane Biology, School of Medicine, Tsinghua University, 100084 Beijing, China
- Medical Systems Biology Research Center, School of Medicine, Tsinghua University, 100084 Beijing, China
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| | - Jian Yang
- State Key Laboratory Breeding Base of Dao-di Herbs, National Resource Center for Chinese Materia Medica, China Academy of Chinese Medical Sciences, 100700 Beijing, China
| | - Yujun Chang
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| | - Liansheng Qiao
- State Key Laboratory of Membrane Biology, School of Medicine, Tsinghua University, 100084 Beijing, China
- Medical Systems Biology Research Center, School of Medicine, Tsinghua University, 100084 Beijing, China
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| | - Honglei Dang
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| | - Kun Luo
- State Key Laboratory of Membrane Biology, School of Medicine, Tsinghua University, 100084 Beijing, China
- Medical Systems Biology Research Center, School of Medicine, Tsinghua University, 100084 Beijing, China
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| | - Hongyan Guo
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| | - Yannan An
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| | - Chengmei Ma
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| | - Hong Shao
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| | - Jie Tian
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| | - Yuan Yuan
- State Key Laboratory Breeding Base of Dao-di Herbs, National Resource Center for Chinese Materia Medica, China Academy of Chinese Medical Sciences, 100700 Beijing, China
| | - Lan Xie
- State Key Laboratory of Membrane Biology, School of Medicine, Tsinghua University, 100084 Beijing, China
- Medical Systems Biology Research Center, School of Medicine, Tsinghua University, 100084 Beijing, China
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| | - Wanli Xing
- State Key Laboratory of Membrane Biology, School of Medicine, Tsinghua University, 100084 Beijing, China
- Medical Systems Biology Research Center, School of Medicine, Tsinghua University, 100084 Beijing, China
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| | - Jing Cheng
- State Key Laboratory of Membrane Biology, School of Medicine, Tsinghua University, 100084 Beijing, China
- Medical Systems Biology Research Center, School of Medicine, Tsinghua University, 100084 Beijing, China
- National Engineering Research Center for Beijing Biochip Technology, 102206 Beijing, China
| |
Collapse
|
11
|
Abstract
Hepatic lipid metabolism is a series of complex processes that control influx and efflux of not only hepatic lipid pools, but also organismal pools. Lipid homeostasis is usually tightly controlled by expression, substrate supply, oxidation and secretion that keep hepatic lipid pools relatively constant. However, perturbations of any of these processes can lead to lipid accumulation in the liver. Although it is thought that these responses are hepatic arms of the 'thrifty genome', they are maladaptive in the context of chronic fatty liver diseases. Ethanol is likely unique among toxins, in that it perturbs almost all aspects of hepatic lipid metabolism. This complex response is due in part to the large metabolic demand placed on the organ by alcohol metabolism, but also appears to involve more nuanced changes in expression and substrate supply. The net effect is that steatosis is a rapid response to alcohol abuse. Although transient steatosis is largely an inert pathology, the chronicity of alcohol-related liver disease seems to require steatosis. Better and more specific understanding of the mechanisms by which alcohol causes steatosis may therefore translate into targeted therapies to treat alcohol-related liver disease and/or prevent its progression.
Collapse
|
12
|
Zhu S, Tan P, Ji R, Xiang X, Cai Z, Dong X, Mai K, Ai Q. Influence of a Dietary Vegetable Oil Blend on Serum Lipid Profiles in Large Yellow Croaker ( Larimichthys crocea). JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:9097-9106. [PMID: 30095902 DOI: 10.1021/acs.jafc.8b03382] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Serum lipid metabolic responses are associated with certain metabolic disorders induced by dietary habits in mammals. However, such associations have not been reported in fish. Lipidomic analyses were performed to investigate fish lipid metabolic responses to a dietary vegetable oil (VO) blend and to elucidate the mechanism of how the dietary VO blend affects serum lipid profiles. Results showed that the dietary VO blend strongly affects serum lipid profiles, especially the ratio of triglyceride/phosphatidylcholine (TAG/PC), via inhibiting hepatic PC biosynthesis and facilitating hepatic and intestinal lipoprotein assembly. Studies in vitro suggested that changes of serum TAG/PC ratio may be partially attributed to altered fatty acid composition in diets. Additionally, the reduction of 16:0/18:1-PC induced by the dietary VO blend may play a role in abnormal lipid deposition through inhibiting PPARA-mediated activation of β-oxidation. These findings suggested that the serum TAG/PC ratio might be a predictive parameter for abnormal lipid metabolism induced by dietary nutrition in fish.
Collapse
Affiliation(s)
- Si Zhu
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture) & Key Laboratory of Mariculture (Ministry of Education) , Ocean University of China , 5 Yushan Road , Qingdao , Shangdong 266003 , China
| | - Peng Tan
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture) & Key Laboratory of Mariculture (Ministry of Education) , Ocean University of China , 5 Yushan Road , Qingdao , Shangdong 266003 , China
| | - Renlei Ji
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture) & Key Laboratory of Mariculture (Ministry of Education) , Ocean University of China , 5 Yushan Road , Qingdao , Shangdong 266003 , China
| | - Xiaojun Xiang
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture) & Key Laboratory of Mariculture (Ministry of Education) , Ocean University of China , 5 Yushan Road , Qingdao , Shangdong 266003 , China
| | - Zuonan Cai
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture) & Key Laboratory of Mariculture (Ministry of Education) , Ocean University of China , 5 Yushan Road , Qingdao , Shangdong 266003 , China
| | - Xiaojing Dong
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture) & Key Laboratory of Mariculture (Ministry of Education) , Ocean University of China , 5 Yushan Road , Qingdao , Shangdong 266003 , China
| | - Kangsen Mai
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture) & Key Laboratory of Mariculture (Ministry of Education) , Ocean University of China , 5 Yushan Road , Qingdao , Shangdong 266003 , China
- Laboratory for Marine Fisheries and Aquaculture , Qingdao National Laboratory for Marine Science and Technology , Qingdao , Shangdong China
| | - Qinghui Ai
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture) & Key Laboratory of Mariculture (Ministry of Education) , Ocean University of China , 5 Yushan Road , Qingdao , Shangdong 266003 , China
- Laboratory for Marine Fisheries and Aquaculture , Qingdao National Laboratory for Marine Science and Technology , Qingdao , Shangdong China
| |
Collapse
|
13
|
Momtazi AA, Banach M, Pirro M, Stein EA, Sahebkar A. MicroRNAs: New Therapeutic Targets for Familial Hypercholesterolemia? Clin Rev Allergy Immunol 2018; 54:224-233. [PMID: 28534160 PMCID: PMC5874276 DOI: 10.1007/s12016-017-8611-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Familial hypercholesterolemia (FH) is the most common inherited form of dyslipidemia and a major cause of premature cardiovascular disease. Management of FH mainly relies on the efficiency of treatments that reduce plasma low-density lipoprotein (LDL) cholesterol (LDL-C) concentrations. MicroRNAs (miRs) have been suggested as emerging regulators of plasma LDL-C concentrations. Notably, there is evidence showing that miRs can regulate the post-transcriptional expression of genes involved in the pathogenesis of FH, including LDLR, APOB, PCSK9, and LDLRAP1. In addition, many miRs are located in genomic loci associated with abnormal levels of circulating lipids and lipoproteins in human plasma. The strong regulatory effects of miRs on the expression of FH-associated genes support of the notion that manipulation of miRs might serve as a potential novel therapeutic approach. The present review describes miRs-targeting FH-associated genes that could be used as potential therapeutic targets in patients with FH or other severe dyslipidemias.
Collapse
Affiliation(s)
- Amir Abbas Momtazi
- Nanotechnology Research Center, Department of Medical Biotechnology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Maciej Banach
- Department of Hypertension, WAM University Hospital in Lodz, Medical University of Lodz (MUL), Zeromskiego 113, 90-549, Lodz, Poland. .,Polish Mother's Memorial Hospital Research Institute (PMMHRI), Lodz, Poland. .,Cardiovascular Research Centre, University of Zielona Gora, Zielona Gora, Poland.
| | - Matteo Pirro
- Unit of Internal Medicine, Angiology and Arteriosclerosis Diseases, Department of Medicine, University of Perugia, Perugia, Italy
| | - Evan A Stein
- Metabolic and Atherosclerosis Research Center, Cincinnati, OH, USA
| | - Amirhossein Sahebkar
- Biotechnology Research Center, Mashhad University of Medical Sciences, Mashhad, 9177948564, Iran. .,School of Medicine, University of Western Australia, Perth, Australia. .,Department of Medical Biotechnology, School of Medicine, Mashhad University of Medical Sciences, P.O. Box: 91779-48564, Mashhad, Iran.
| |
Collapse
|
14
|
Massafra V, van Mil SWC. Farnesoid X receptor: A "homeostat" for hepatic nutrient metabolism. Biochim Biophys Acta Mol Basis Dis 2017; 1864:45-59. [PMID: 28986309 DOI: 10.1016/j.bbadis.2017.10.003] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 09/27/2017] [Accepted: 10/02/2017] [Indexed: 02/06/2023]
Abstract
The Farnesoid X receptor (FXR) is a nuclear receptor activated by bile acids (BAs). BAs are amphipathic molecules that serve as fat solubilizers in the intestine under postprandial conditions. In the post-absorptive state, BAs bind FXR in the hepatocytes, which in turn provides feedback signals on BA synthesis and transport and regulates lipid, glucose and amino acid metabolism. Therefore, FXR acts as a homeostat of all three classes of nutrients, fats, sugars and proteins. Here we re-analyze the function of FXR in the perspective of nutritional metabolism, and discuss the role of FXR in liver energy homeostasis in postprandial, post-absorptive and fasting/starvation states. FXR, by regulating nutritional metabolism, represses autophagy in conditions of nutrient abundance, and controls the metabolic needs of proliferative cells. In addition, FXR regulates inflammation via direct effects and via its impact on nutrient metabolism. These functions indicate that FXR is an attractive therapeutic target for liver diseases.
Collapse
Affiliation(s)
- Vittoria Massafra
- Center for Molecular Medicine, UMC Utrecht, Utrecht, The Netherlands
| | | |
Collapse
|
15
|
Soubeyrand S, Martinuk A, McPherson R. TRIB1 is a positive regulator of hepatocyte nuclear factor 4-alpha. Sci Rep 2017; 7:5574. [PMID: 28717196 PMCID: PMC5514136 DOI: 10.1038/s41598-017-05768-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Accepted: 06/02/2017] [Indexed: 01/06/2023] Open
Abstract
The TRIB1 locus has been linked to both cardiovascular disease and hepatic steatosis. Recent efforts have revealed TRIB1 to be a major regulator of liver function, largely, but not exclusively, via CEBPA degradation. We recently uncovered a functional interaction between TRIB1 and HNF4A, another key regulator of hepatic function, whose molecular underpinnings remained to be clarified. Here we have extended these findings. In hepatoma models, HNF4A levels were found to depend on TRIB1, independently of its impact on CEBPA. Using a reporter assay model, MTTP reporter activity, which depends on HNF4A, positively correlated with TRIB1 levels. Confocal microscopy demonstrated partial colocalization of TRIB1 and HNF4A. Using overexpressed proteins we demonstrate that TRIB1 and HNF4A can form complexes in vivo. Mapping of the interaction interfaces identified two distinct regions within TRIB1 which associated with the N-terminal region of HNF4A. Lastly, the TRIB1-HNF4A interaction resisted competition with a CEPBA-derived peptide, suggesting different binding modalities. Together these findings establish that TRIB1 is required for HNF4A function. This regulatory axis represents a novel CEBPA-independent aspect of TRIB1 function predicted to play an important role in liver physiology.
Collapse
Affiliation(s)
- Sébastien Soubeyrand
- Atherogenomics Laboratory, University of Ottawa Heart Institute, Ottawa, Canada.
| | - Amy Martinuk
- Atherogenomics Laboratory, University of Ottawa Heart Institute, Ottawa, Canada
| | - Ruth McPherson
- Atherogenomics Laboratory, University of Ottawa Heart Institute, Ottawa, Canada.
| |
Collapse
|
16
|
Sasaki A, Hiwatashi K, Kumagai M, Hata K, Kobayashi M. Relationships between the expression of hepatocyte nuclear factors and factors essential for lipoprotein production in a human mesenchymal stem cell line, UE7T-13. Biosci Biotechnol Biochem 2017; 81:262-270. [DOI: 10.1080/09168451.2016.1254530] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Abstract
To clarify the mechanisms regulating lipoprotein production by hepatocyte nuclear factors (HNFs), we generated four kinds of transfectants in human bone marrow mesenchymal stem cells: UE7T-13, stably expressing FOXA2 (also known as HNF3β), HNF4α, HNF1α or co-expressing HNF4α, and HNF1α (HNF4α/HNF1α). In HNF4α/HNF1α transfectants, cellular contents of triglycerides (TG) and cholesterol were markedly higher than in UE7T-13 cells and comparable to those in human hepatoma HepG2 cells. However, TG and cholesterol, which are secreted from cells as components of lipoproteins, were hardly detected in the medium for any of the transfectants. ApoB100 and MTP, which are essential for the formation and secretion of lipoproteins, were undetectable and detected at low levels, respectively, in HNF4α/HNF1α transfectants. We suggest that enforced co-expression of HNF4α and HNF1α is effective for cellular lipid accumulation, while additional factors are probably required for lipoprotein formation and secretion.
Collapse
Affiliation(s)
- Akira Sasaki
- Graduate School of Bioresource Sciences, Akita Prefectural University, Akita, Japan
- Food Processing Research Station, Akita Research Institute of Food and Brewing, Akita, Japan
| | - Kazuyuki Hiwatashi
- Food Processing Research Station, Akita Research Institute of Food and Brewing, Akita, Japan
| | - Masanori Kumagai
- Food Processing Research Station, Akita Research Institute of Food and Brewing, Akita, Japan
| | - Keishi Hata
- Food Processing Research Station, Akita Research Institute of Food and Brewing, Akita, Japan
| | - Masayuki Kobayashi
- Graduate School of Bioresource Sciences, Akita Prefectural University, Akita, Japan
| |
Collapse
|
17
|
RNA helicase DDX3 maintains lipid homeostasis through upregulation of the microsomal triglyceride transfer protein by interacting with HNF4 and SHP. Sci Rep 2017; 7:41452. [PMID: 28128295 PMCID: PMC5269733 DOI: 10.1038/srep41452] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 12/19/2016] [Indexed: 01/06/2023] Open
Abstract
Multifunctional RNA helicase DDX3 participates in HCV infection, one of the major causes of hepatic steatosis. Here, we investigated the role of DDX3 in hepatic lipid metabolism. We found that HCV infection severely reduced DDX3 expression. Analysis of intracellular triglyceride and secreted ApoB indicated that lipid accumulations were increased while ApoB secretion were decreased in DDX3 knockdown HuH7 and HepG2 cell lines. Down-regulation of DDX3 significantly decreased protein and transcript expression of microsomal triglyceride transfer protein (MTP), a key regulator of liver lipid homeostasis. Moreover, DDX3 interacted with hepatocyte nuclear factor 4 (HNF4) and small heterodimer partner (SHP), and synergistically up-regulated HNF4-mediated transactivation of MTP promoter via its ATPase activity. Further investigation revealed that DDX3 interacted with CBP/p300 and increased the promoter binding affinity of HNF4 by enhancing HNF4 acetylation. Additionally, DDX3 partially relieved the SHP-mediated suppression on MTP promoter by competing with SHP for HNF4 binding which disrupted the inactive HNF4/SHP heterodimer while promoted the formation of the active HNF4 homodimer. Collectively, these results imply that DDX3 regulates MTP gene expression and lipid homeostasis through interplay with HNF4 and SHP, which may also reveal a novel mechanism of HCV-induced steatosis.
Collapse
|
18
|
Moreno M, Silvestri E, Coppola M, Goldberg IJ, Huang LS, Salzano AM, D'Angelo F, Ehrenkranz JR, Goglia F. 3,5,3'-Triiodo-L-Thyronine- and 3,5-Diiodo-L-Thyronine- Affected Metabolic Pathways in Liver of LDL Receptor Deficient Mice. Front Physiol 2016; 7:545. [PMID: 27909409 PMCID: PMC5112267 DOI: 10.3389/fphys.2016.00545] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 10/28/2016] [Indexed: 12/25/2022] Open
Abstract
3,5,3′-triiodo-L-thyronine (T3) and 3,5-diiodo-L-thyronine (T2), when administered to a model of familial hypercholesterolemia, i.e., low density lipoprotein receptor (LDLr)-knockout (Ldlr−/−) mice fed with a Western type diet (WTD), dramatically reduce circulating total and very low-density lipoprotein/LDL cholesterol with decreased liver apolipoprotein B (ApoB) production. The aim of the study was to highlight putative molecular mechanisms to manage cholesterol levels in the absence of LDLr. A comprehensive comparative profiling of changes in expression of soluble proteins in livers from Ldlr−/− mice treated with either T3 or T2 was performed. From a total proteome of 450 liver proteins, 25 identified proteins were affected by both T2 and T3, 18 only by T3 and 9 only by T2. Using in silico analyses, an overlap was observed with 11/14 pathways common to both iodothyronines, with T2 and T3 preferentially altering sub-networks centered around hepatocyte nuclear factor 4 α (HNF4α) and peroxisome proliferator-activated receptor α (PPARα), respectively. Both T2 and T3 administration significantly reduced nuclear HNF4α protein content, while T2, but not T3, decreased the expression levels of the HNFα transcriptional coactivator PGC-1α. Lower PPARα levels were found only following T3 treatment while both T3 and T2 lowered liver X receptor α (LXRα) nuclear content. Overall, this study, although it was not meant to investigate the use of T2 and T3 as a therapeutic agent, provides novel insights into the regulation of hepatic metabolic pathways involved in T3- and T2-driven cholesterol reduction in Ldlr−/− mice.
Collapse
Affiliation(s)
- Maria Moreno
- Department of Science and Technologies, University of Sannio Benevento, Italy
| | - Elena Silvestri
- Department of Science and Technologies, University of Sannio Benevento, Italy
| | - Maria Coppola
- Department of Science and Technologies, University of Sannio Benevento, Italy
| | - Ira J Goldberg
- Department of Medicine, Columbia University New York, NY, USA
| | - Li-Shin Huang
- Department of Medicine, Columbia University New York, NY, USA
| | - Anna M Salzano
- Proteomics and Mass Spectrometry Laboratory, Instituto per Il Sistema Produzione Animale in Ambiente Mediterraneo, National Research Council Napoli, Italy
| | | | - Joel R Ehrenkranz
- Department of Medicine, Intermountain Healthcare Salt Lake City, UT, USA
| | - Fernando Goglia
- Department of Science and Technologies, University of Sannio Benevento, Italy
| |
Collapse
|
19
|
Erami K, Tanaka Y, Kawamura S, Miyago M, Sawazaki A, Imaizumi K, Sato M. Dietary Egg Yolk Supplementation Improves Low-Protein-Diet-Induced Fatty Liver in Rats. J Nutr Sci Vitaminol (Tokyo) 2016; 62:240-248. [PMID: 27725409 DOI: 10.3177/jnsv.62.240] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Egg yolk is an important source of nutrients and contains different bioactive substances. In the present study, we studied the benefits of egg yolk in preventing low-protein-diet-induced fatty liver in rats. Rats were fed the following diets, which were based on the AIN-76 formula, for 2 wk: an adequate-protein diet containing 20% casein (C), a low-protein diet containing 5% casein (LP-C), a low-protein diet supplemented with 12.5% egg yolk (LP-EY), and a low-protein diet supplemented with 4.1% egg yolk oil (LP-EYO). The low-protein diets were adjusted to contain 4.13% protein and 4.7% lipids. The LP-C diet resulted in a greater increase in the liver trigriceride (TG) and the vacuolation and a greater decrease in the serum TG and free fatty acid (FFA) than did the C diet. These deviations in the serum and liver TG, serum FFA levels and the liver histopathology were corrected in rats fed the LP-EY diet but not in those fed the LP-EYO diet. Compared to rats fed the LP-C diet, although the activities of lipogenesis-related enzymes (fatty acid synthase, glucose-6-phosphate dehydrogenase, and malic enzyme) decreased in rats fed both of the LP-EY and LP-EYO diets, the level of the microsomal TG transfer protein (MTP) increased only in rats fed the LP-EY diet. Collectively, these results suggest that dietary egg yolk supplementation decreases the LP diet-induced accumulation of TG in the liver by increasing transport of TG in the liver, and egg yolk oil alone is not sufficient enough to bring about these benefits.
Collapse
Affiliation(s)
- Kazuo Erami
- Laboratory of Nutrition Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University
| | | | | | | | | | | | | |
Collapse
|
20
|
Radović B, Vujić N, Leopold C, Schlager S, Goeritzer M, Patankar JV, Korbelius M, Kolb D, Reindl J, Wegscheider M, Tomin T, Birner-Gruenberger R, Schittmayer M, Groschner L, Magnes C, Diwoky C, Frank S, Steyrer E, Du H, Graier WF, Madl T, Kratky D. Lysosomal acid lipase regulates VLDL synthesis and insulin sensitivity in mice. Diabetologia 2016; 59:1743-52. [PMID: 27153842 PMCID: PMC4930475 DOI: 10.1007/s00125-016-3968-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 03/29/2016] [Indexed: 01/08/2023]
Abstract
AIMS/HYPOTHESIS Lysosomal acid lipase (LAL) hydrolyses cholesteryl esters and triacylglycerols (TG) within lysosomes to mobilise NEFA and cholesterol. Since LAL-deficient (Lal (-/-) ) mice suffer from progressive loss of adipose tissue and severe accumulation of lipids in hepatic lysosomes, we hypothesised that LAL deficiency triggers alternative energy pathway(s). METHODS We studied metabolic adaptations in Lal (-/-) mice. RESULTS Despite loss of adipose tissue, Lal (-/-) mice show enhanced glucose clearance during insulin and glucose tolerance tests and have increased uptake of [(3)H]2-deoxy-D-glucose into skeletal muscle compared with wild-type mice. In agreement, fasted Lal (-/-) mice exhibit reduced glucose and glycogen levels in skeletal muscle. We observed 84% decreased plasma leptin levels and significantly reduced hepatic ATP, glucose, glycogen and glutamine concentrations in fed Lal (-/-) mice. Markedly reduced hepatic acyl-CoA concentrations decrease the expression of peroxisome proliferator-activated receptor α (PPARα) target genes. However, treatment of Lal (-/-) mice with the PPARα agonist fenofibrate further decreased plasma TG (and hepatic glucose and glycogen) concentrations in Lal (-/-) mice. Depletion of hepatic nuclear factor 4α and forkhead box protein a2 in fasted Lal (-/-) mice might be responsible for reduced expression of microsomal TG transfer protein, defective VLDL synthesis and drastically reduced plasma TG levels. CONCLUSIONS/INTERPRETATION Our findings indicate that neither activation nor inactivation of PPARα per se but rather the availability of hepatic acyl-CoA concentrations regulates VLDL synthesis and subsequent metabolic adaptations in Lal (-/-) mice. We conclude that decreased plasma VLDL production enhances glucose uptake into skeletal muscle to compensate for the lack of energy supply.
Collapse
Affiliation(s)
- Branislav Radović
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
| | - Nemanja Vujić
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
| | - Christina Leopold
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
| | - Stefanie Schlager
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
| | - Madeleine Goeritzer
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
| | - Jay V Patankar
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
- Center for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Melanie Korbelius
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
| | - Dagmar Kolb
- Center for Medical Research/Institute of Cell Biology, Histology and Embryology, Medical University of Graz, Graz, Austria
| | - Julia Reindl
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
| | - Martin Wegscheider
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
| | - Tamara Tomin
- Institute of Pathology, Medical University of Graz, Graz, Austria
- Omics Center Graz, BioTechMed-Graz, Graz, Austria
| | - Ruth Birner-Gruenberger
- Institute of Pathology, Medical University of Graz, Graz, Austria
- Omics Center Graz, BioTechMed-Graz, Graz, Austria
| | - Matthias Schittmayer
- Institute of Pathology, Medical University of Graz, Graz, Austria
- Omics Center Graz, BioTechMed-Graz, Graz, Austria
| | - Lukas Groschner
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
- Center for Neural Circuits and Behaviour, University of Oxford, Oxford, UK
| | - Christoph Magnes
- Health, Bioanalytik und Metabolomics, Joanneum Research, Graz, Austria
| | - Clemens Diwoky
- Institute of Biomedical Engineering, Graz University of Technology, Graz, Austria
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Saša Frank
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
| | - Ernst Steyrer
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
| | - Hong Du
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Wolfgang F Graier
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
| | - Tobias Madl
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria
- Omics Center Graz, BioTechMed-Graz, Graz, Austria
- Department of Chemistry, Technical University, Munich, Germany
- Institute of Structural Biology, Helmholtz Zentrum, Munich, Germany
| | - Dagmar Kratky
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010, Graz, Austria.
| |
Collapse
|
21
|
Vallianou I, Dafou D, Vassilaki N, Mavromara P, Hadzopoulou-Cladaras M. Hepatitis C virus suppresses Hepatocyte Nuclear Factor 4 alpha, a key regulator of hepatocellular carcinoma. Int J Biochem Cell Biol 2016; 78:315-326. [PMID: 27477312 DOI: 10.1016/j.biocel.2016.07.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 07/20/2016] [Accepted: 07/26/2016] [Indexed: 12/18/2022]
Abstract
Hepatitis C Virus (HCV) infection presents with a disturbed lipid profile and can evolve to hepatic steatosis and hepatocellular carcinoma (HCC). Hepatocyte Nuclear Factor 4 alpha (HNF4α) is the most abundant transcription factor in the liver, a key regulator of hepatic lipid metabolism and a critical determinant of Epithelial to Mesenchymal Transition and hepatic development. We have previously shown that transient inhibition of HNF4α initiates transformation of immortalized hepatocytes through a feedback loop consisting of miR-24, IL6 receptor (IL6R), STAT3, miR-124 and miR-629, suggesting a central role of HNF4α in HCC. However, the role of HNF4α in Hepatitis C Virus (HCV)-related hepatocarcinoma has not been evaluated and remains controversial. In this study, we provide strong evidence suggesting that HCV downregulates HNF4α expression at both transcriptional and translational levels. The observed decrease of HNF4α expression correlated with the downregulation of its downstream targets, HNF1α and MTP. Ectopic overexpression of HCV proteins also exhibited an inhibitory effect on HNF4α levels. The inhibition of HNF4α expression by HCV appeared to be mediated at transcriptional level as HCV proteins suppressed HNF4α gene promoter activity. HCV also up-regulated IL6R, activated STAT3 protein phosphorylation and altered the expression of acute phase genes. Furthermore, as HCV triggered the loss of HNF4α a consequent change of miR-24, miR-629 or miR-124 was observed. Our findings demonstrated that HCV-related HCC could be mediated through HNF4α-microRNA deregulation implying a possible role of HNF4α in HCV hepatocarcinogenesis. HCV inhibition of HNF4α could be sustained to promote HCC.
Collapse
Affiliation(s)
- Ioanna Vallianou
- Department of Genetics, Development and Molecular Biology, School of Biology, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Dimitra Dafou
- Department of Genetics, Development and Molecular Biology, School of Biology, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Niki Vassilaki
- Molecular Virology Laboratory, Hellenic Pasteur Institute, Athens, Greece
| | - Penelope Mavromara
- Molecular Virology Laboratory, Hellenic Pasteur Institute, Athens, Greece
| | - Margarita Hadzopoulou-Cladaras
- Department of Genetics, Development and Molecular Biology, School of Biology, Aristotle University of Thessaloniki, Thessaloniki, Greece.
| |
Collapse
|
22
|
Zhou L, Irani S, Sirwi A, Hussain MM. MicroRNAs regulating apolipoprotein B-containing lipoprotein production. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:2062-2068. [PMID: 26923435 DOI: 10.1016/j.bbalip.2016.02.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 02/18/2016] [Accepted: 02/22/2016] [Indexed: 02/07/2023]
Abstract
MicroRNAs (miRs) are small, non-coding RNAs that regulate gene expression and have been implicated in many pathological conditions. Significant progress has been made to unveil their role in lipid metabolism. This review aims at summarizing the role of different miRs that regulate hepatic assembly and secretion of apolipoprotein B (apoB)-containing lipoproteins. Overproduction and/or impaired clearance of these lipoproteins from circulation increase plasma concentrations of lipids enhancing risk for cardiovascular disease. So far, three miRs, miR-122, miR-34a, and miR-30c have been shown to modulate hepatic production of apoB-containing low density lipoproteins. In this review, we will first provide a brief overview of lipid metabolism and apoB-containing lipoprotein assembly to orient readers to different steps that have been shown to be regulated by miRs. Then, we will discuss the role of each miR on plasma lipids and atherosclerotic burden. Furthermore, we will summarize mechanistic studies explaining how these miRs regulate hepatic lipid synthesis, fatty acid oxidation, and lipoprotein secretion. Finally, we will briefly highlight the potential use of each miR as a therapeutic drug for treating cardiovascular diseases. This article is part of a Special Issue entitled: MicroRNAs and lipid/energy metabolism and related diseases edited by Carlos Fernández-Hernando and Yajaira Suárez.
Collapse
Affiliation(s)
- Liye Zhou
- School of Graduate Studies, Molecular and Cell Biology Program, USA; Department of Cell Biology, SUNY Downstate Medical Center, Brooklyn, NY, USA; Department of Pediatrics, SUNY Downstate Medical Center, Brooklyn, NY, USA
| | - Sara Irani
- School of Graduate Studies, Molecular and Cell Biology Program, USA; Department of Cell Biology, SUNY Downstate Medical Center, Brooklyn, NY, USA; Department of Pediatrics, SUNY Downstate Medical Center, Brooklyn, NY, USA
| | - Alaa Sirwi
- School of Graduate Studies, Molecular and Cell Biology Program, USA; Department of Cell Biology, SUNY Downstate Medical Center, Brooklyn, NY, USA; Department of Pediatrics, SUNY Downstate Medical Center, Brooklyn, NY, USA
| | - M Mahmood Hussain
- Department of Cell Biology, SUNY Downstate Medical Center, Brooklyn, NY, USA; Department of Pediatrics, SUNY Downstate Medical Center, Brooklyn, NY, USA; VA New York Harbor Healthcare System, Brooklyn, NY, USA.
| |
Collapse
|
23
|
Yamaguchi N, Sunto A, Goda T, Suruga K. Competitive regulation of human intestinal β-carotene 15,15′-monooxygenase 1 (BCMO1) gene expression by hepatocyte nuclear factor (HNF)-1α and HNF-4α. Life Sci 2014; 119:34-9. [DOI: 10.1016/j.lfs.2014.10.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 09/17/2014] [Accepted: 10/16/2014] [Indexed: 10/24/2022]
|
24
|
Hepatocyte nuclear factor 4α and downstream secreted phospholipase A2 GXIIB regulate production of infectious hepatitis C virus. J Virol 2013; 88:612-27. [PMID: 24173221 DOI: 10.1128/jvi.02068-13] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Hepatitis C virus (HCV) is a major cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma in humans. The life cycle of HCV is closely associated with the metabolism of lipids, especially very-low-density lipoprotein (VLDL) in hepatocytes. Hepatocyte nuclear factor 4α (HNF4α), the most abundant transcription factor in the liver, regulates the VLDL secretory pathway. However, the effects of HNF4α on the HCV life cycle are unclear. In this study, we investigated the regulatory effects of HNF4α on HCV assembly and secretion. HCV in HNF4α-deficient hepatocytes showed reduced assembly and secretion but unchanged entry and RNA replication. Bezafibrate, a chemical inhibitor of HNF4α, suppressed HCV assembly and secretion. HNF4α downregulation resulted in rearrangement of cytosolic lipid droplets (LDs), as evidenced by the aggregation of large LDs and distorted cytosolic distribution. Phospholipase A2 GXIIB (PLA2GXIIB), an HNF4α-regulated factor involved in VLDL secretion, was found to be crucial in HCV secretion. PLA2GXIIB expression was upregulated in hepatocytes harboring HCV subgenomic replicons or in HCV-infected hepatocytes. This upregulation was transcriptionally controlled in an HNF4α-dependent manner after HCV infection. Furthermore, PLA2GXIIB combined with microsomal triglyceride transfer protein was found to be responsible for the regulation of HNF4α-induced HCV infectivity. These results suggest that HNF4α and its downstream PLA2GXIIB are important factors affecting the late stage of the HCV life cycle and may serve as potential drug targets for the treatment of HCV infection.
Collapse
|
25
|
Chen Z, Gropler MC, Mitra MS, Finck BN. Complex interplay between the lipin 1 and the hepatocyte nuclear factor 4 α (HNF4α) pathways to regulate liver lipid metabolism. PLoS One 2012; 7:e51320. [PMID: 23236470 PMCID: PMC3517414 DOI: 10.1371/journal.pone.0051320] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 10/31/2012] [Indexed: 01/18/2023] Open
Abstract
Lipin 1 is a bifunctional protein that serves as a metabolic enzyme in the triglyceride synthesis pathway and regulates gene expression through direct protein-protein interactions with DNA-bound transcription factors in liver. Herein, we demonstrate that lipin 1 is a target gene of the hepatocyte nuclear factor 4α (HNF4α), which induces lipin 1 gene expression in cooperation with peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) through a nuclear receptor response element in the first intron of the lipin 1 gene. The results of a series of gain-of-function and loss-of-function studies demonstrate that lipin 1 coactivates HNF4α to activate the expression of a variety of genes encoding enzymes involved in fatty acid catabolism. In contrast, lipin 1 reduces the ability of HNF4α to induce the expression of genes encoding apoproteins A4 and C3. Although the ability of lipin to diminish HNF4α activity on these promoters required a direct physical interaction between the two proteins, lipin 1 did not occupy the promoters of the repressed genes and enhances the intrinsic activity of HNF4α in a promoter-independent context. Thus, the induction of lipin 1 by HNF4α may serve as a mechanism to affect promoter selection to direct HNF4α to promoters of genes encoding fatty acid oxidation enzymes.
Collapse
Affiliation(s)
- Zhouji Chen
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Matthew C. Gropler
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Mayurranjan S. Mitra
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Brian N. Finck
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail:
| |
Collapse
|
26
|
Dai K, Hussain MM. NR2F1 disrupts synergistic activation of the MTTP gene transcription by HNF-4α and HNF-1α. J Lipid Res 2012; 53:901-908. [PMID: 22357705 DOI: 10.1194/jlr.m025130] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Regulation of microsomal triglyceride transfer protein (MTP) expression mainly occurs at the transcriptional level. We have previously shown that MTTP gene expression was repressed in nondifferentiated intestinal cells by nuclear receptor 2 family 1 (NR2F1). However, mechanisms involved in the repression of MTP by NR2F1 were not elucidated. Here, we show that MTP expression requires hepatic nuclear factor (HNF)-4α transcription factor. Different HNF-1 proteins synergistically enhance MTP promoter activity along with HNF-4α by binding to different cis elements. NR2F1 does not alter individual effects of HNF-4α and HNF-1 proteins on the MTTP gene promoter. However, NR2F1 suppresses synergistic activation of the MTP promoter by HNF-4α/HNF-1α by binding to a direct repeat 1 (DR1) element. This suppression is further enhanced in the presence of nuclear receptor corepressor 1. In short, these studies identified a novel mechanism of MTP repression that involves binding of NR2F1 to the DR1 element and recruitment of corepressors. In this mechanism, NR2F1 does not affect activities of individual transcription factors; instead, it abrogates synergistic activation by HNF-4α and HNF-1 proteins.
Collapse
Affiliation(s)
- Kezhi Dai
- Departments of Cell Biology and Pediatrics, Program of Molecular and Cellular Biology, School of Graduate Studies, SUNY Downstate Medical Center, Brooklyn, NY
| | - M Mahmood Hussain
- Departments of Cell Biology and Pediatrics, Program of Molecular and Cellular Biology, School of Graduate Studies, SUNY Downstate Medical Center, Brooklyn, NY.
| |
Collapse
|
27
|
Zhang Z, Liu J, Xi Y, Yang R, Chen H, Li Z, Liu D, Liang C. Two novel cis-elements involved in hepatocyte nuclear factor 4α regulation of acyl-coenzyme A:cholesterol acyltransferase 2 expression. Acta Biochim Biophys Sin (Shanghai) 2012; 44:162-71. [PMID: 22155889 DOI: 10.1093/abbs/gmr102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Acyl-coenzyme A:cholesterol acyltransferase 2 (ACAT2) is important for cholesterol ester synthesis and secretion. A previous study revealed that ACAT2 gene promoter activity was upregulated by hepatocyte nuclear factor 4α (HNF4α) through two sites around -247 and -311 of ACAT2 gene promoter. Here, we identified two novel cis-elements, site I (-1006 to -898) and site II (-38 to -29), which are important for HNF4α effect. In HepG2 cells, mutation of site I decreased ACAT2 gene promoter activity to one-fifth of that of the wild type, while mutation of site II reduced promoter activity to less than one-tenth of that of the wild type. In 293T cells, mutation of these two cis-elements profoundly impaired the HNF4α induction effect. When either of these two elements was inserted into pGL3-promoter, HNF4α induced promoter activity through the inserted element, while mutation of the element impaired HNF4α induction effect. In electrophoretic mobility shift assay and chromatin immunoprecipitation experiment, HNF4α bound to these two elements. Thus, the two cis-elements are important for HNF4α effect on ACAT2 gene transcription. We also showed that HNF4α positively regulates ACAT2 gene expression at mRNA level. Overexpression of HNF4α increased ACAT2 expression, whereas knockdown of HNF4α decreased ACAT2 expression. Peroxisome proliferator-activated receptor gamma coactivator 1α (PCG1α), a coactivator of HNF4α, increased ACAT2 expression, while small heterodimer partner (SHP), a corepressor of HNF4α, decreased ACAT2 expression. These results provide more insights into transcriptional regulation of ACAT2 expression.
Collapse
Affiliation(s)
- Zhuqin Zhang
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Science, Chinese Academy of Medical Sciences, Beijing, China
| | | | | | | | | | | | | | | |
Collapse
|
28
|
Omega-3 fatty acids and cardiovascular disease: effects on risk factors, molecular pathways, and clinical events. J Am Coll Cardiol 2011; 58:2047-67. [PMID: 22051327 DOI: 10.1016/j.jacc.2011.06.063] [Citation(s) in RCA: 1116] [Impact Index Per Article: 85.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 06/08/2011] [Accepted: 06/16/2011] [Indexed: 11/22/2022]
Abstract
We reviewed available evidence for cardiovascular effects of n-3 polyunsaturated fatty acid (PUFA) consumption, focusing on long chain (seafood) n-3 PUFA, including their principal dietary sources, effects on physiological risk factors, potential molecular pathways and bioactive metabolites, effects on specific clinical endpoints, and existing dietary guidelines. Major dietary sources include fatty fish and other seafood. n-3 PUFA consumption lowers plasma triglycerides, resting heart rate, and blood pressure and might also improve myocardial filling and efficiency, lower inflammation, and improve vascular function. Experimental studies demonstrate direct anti-arrhythmic effects, which have been challenging to document in humans. n-3 PUFA affect a myriad of molecular pathways, including alteration of physical and chemical properties of cellular membranes, direct interaction with and modulation of membrane channels and proteins, regulation of gene expression via nuclear receptors and transcription factors, changes in eicosanoid profiles, and conversion of n-3 PUFA to bioactive metabolites. In prospective observational studies and adequately powered randomized clinical trials, benefits of n-3 PUFA seem most consistent for coronary heart disease mortality and sudden cardiac death. Potential effects on other cardiovascular outcomes are less-well-established, including conflicting evidence from observational studies and/or randomized trials for effects on nonfatal myocardial infarction, ischemic stroke, atrial fibrillation, recurrent ventricular arrhythmias, and heart failure. Research gaps include the relative importance of different physiological and molecular mechanisms, precise dose-responses of physiological and clinical effects, whether fish oil provides all the benefits of fish consumption, and clinical effects of plant-derived n-3 PUFA. Overall, current data provide strong concordant evidence that n-3 PUFA are bioactive compounds that reduce risk of cardiac death. National and international guidelines have converged on consistent recommendations for the general population to consume at least 250 mg/day of long-chain n-3 PUFA or at least 2 servings/week of oily fish.
Collapse
|
29
|
Choi SH, Ginsberg HN. Increased very low density lipoprotein (VLDL) secretion, hepatic steatosis, and insulin resistance. Trends Endocrinol Metab 2011; 22:353-63. [PMID: 21616678 PMCID: PMC3163828 DOI: 10.1016/j.tem.2011.04.007] [Citation(s) in RCA: 249] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2011] [Revised: 04/18/2011] [Accepted: 04/19/2011] [Indexed: 12/14/2022]
Abstract
Insulin resistance (IR) affects not only the regulation of carbohydrate metabolism but all aspects of lipid and lipoprotein metabolism. IR is associated with increased secretion of VLDL and increased plasma triglycerides, as well as with hepatic steatosis, despite the increased VLDL secretion. Here we link IR with increased VLDL secretion and hepatic steatosis at both the physiologic and molecular levels. Increased VLDL secretion, together with the downstream effects on high density lipoprotein (HDL) cholesterol and low density lipoprotein (LDL) size, is proatherogenic. Hepatic steatosis is a risk factor for steatohepatitis and cirrhosis. Understanding the complex inter-relationships between IR and these abnormalities of liver lipid homeostasis will provide insights relevant to new therapies for these increasing clinical problems.
Collapse
Affiliation(s)
- Sung Hee Choi
- Internal Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seoul, Korea
| | - Henry N Ginsberg
- Columbia University College of Physicians and Surgeons, New York, NY, USA
- whom correspondence should be addressed.
| |
Collapse
|
30
|
Higuchi N, Kato M, Tanaka M, Miyazaki M, Takao S, Kohjima M, Kotoh K, Enjoji M, Nakamuta M, Takayanagi R. Effects of insulin resistance and hepatic lipid accumulation on hepatic mRNA expression levels of apoB, MTP and L-FABP in non-alcoholic fatty liver disease. Exp Ther Med 2011; 2:1077-1081. [PMID: 22977624 DOI: 10.3892/etm.2011.328] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Accepted: 07/25/2011] [Indexed: 12/15/2022] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) is considered a hepatic manifestation of metabolic syndrome, which is known to be associated with insulin resistance (IR). NAFLD occurs when the rate of hepatic fatty acid uptake from plasma and de novo fatty acid synthesis is greater than the rate of fatty acid oxidation and excretion as very low-density lipoprotein (VLDL). To estimate the effects of IR on hepatic lipid excretion, mRNA expression levels of genes involved in VLDL assembly were analyzed in NAFLD liver. Twenty-two histologically proven NAFLD patients and 10 healthy control subjects were enrolled in this study. mRNA was extracted from liver biopsy samples and real-time PCR was performed to quantify the expression levels of apolipoprotein B (apoB), microsomal triglyceride transfer protein (MTP) and liver fatty-acid binding protein (L-FABP). Hepatic expression levels of the genes were compared between NAFLD patients and control subjects. In NAFLD patients, we also examined correlations between expression levels of the genes and metabolic factors, including IR, and the extent of obesity and hepatic lipid accumulation. Hepatic expression levels of apoB, MTP and L-FABP were significantly up-regulated in NAFLD patients compared to control subjects. The expression levels of MTP were correlated with those of apoB, but not with those of L-FABP. In the NAFLD liver, the expression levels of MTP were significantly reduced in patients with HOMA-IR >2.5. In addition, a significant reduction in MTP expression was observed in livers with advanced steatosis. Enhanced expression of genes involved in VLDL assembly may be promoted to release excess lipid from NAFLD livers. However, the progression of IR and hepatic steatosis may attenuate this compensatory process.
Collapse
Affiliation(s)
- Nobito Higuchi
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582
| | | | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Hussain MM, Nijstad N, Franceschini L. Regulation of microsomal triglyceride transfer protein. ACTA ACUST UNITED AC 2011; 6:293-303. [PMID: 21808658 DOI: 10.2217/clp.11.21] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Microsomal triglyceride transfer protein (MTP) facilitates the transport of dietary and endogenous fat by the intestine and liver by assisting in the assembly and secretion of triglyceride-rich apolipoprotein B-containing lipoproteins. Higher concentrations of apolipoprotein B lipoproteins predispose individuals to various cardiovascular and metabolic diseases such as atherosclerosis, diabetes, obesity and the metabolic syndrome. These can potentially be avoided by reducing MTP activity. In this article, we discuss regulation of MTP during development, cellular differentiation and diurnal variation. Furthermore, we focus on the regulation of MTP that occurs at transcriptional, post-transcriptional and post-translational levels. Transcriptional regulation of MTP depends on a few highly conserved cis-elements in the promoter. Several transcription factors that bind to these elements and either increase or decrease MTP expression have been identified. Additionally, MTP is regulated by macronutrients, hormones and other factors. This article will address the many ways in which MTP is regulated and advance the idea that reducing MTP levels, rather than its inhibition, might be an option to lower plasma lipids.
Collapse
Affiliation(s)
- M Mahmood Hussain
- Departments of Cell Biology and Pediatrics, The State University of New York, Downstate Medical Center, 450 Clarkson Ave, Brooklyn, NY 11203, USA
| | | | | |
Collapse
|
32
|
Yao Y, Lu S, Huang Y, Beeman-Black CC, Lu R, Pan X, Hussain MM, Black DD. Regulation of microsomal triglyceride transfer protein by apolipoprotein A-IV in newborn swine intestinal epithelial cells. Am J Physiol Gastrointest Liver Physiol 2011; 300:G357-63. [PMID: 21127258 PMCID: PMC3043654 DOI: 10.1152/ajpgi.00353.2010] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Apolipoprotein (apo) A-IV overexpression enhances chylomicron (CM) assembly and secretion in newborn swine intestinal epithelial cells by producing larger particles (Lu S, Yao Y, Cheng X, Mitchell S, Leng S, Meng S, Gallagher JW, Shelness GS, Morris GS, Mahan J, Frase S, Mansbach CM, Weinberg RB, Black DD. J Biol Chem 281: 3473-3483, 2006). To determine the impact of apo A-IV on microsomal triglyceride transfer protein (MTTP), IPEC-1 cell lines containing a tetracycline-regulatable expression system were used to overexpress native swine apo A-IV and "piglike" human apo A-IV, a mutant human apo A-IV with deletion of the EQQQ-rich COOH-terminus, previously shown to upregulate basolateral triglyceride (TG) secretion 5-fold and 25-fold, respectively. Cells were incubated 24 h with and without doxycycline and oleic acid (OA, 0.8 mM). Overexpression of the native swine apo A-IV and piglike human apo A-IV increased MTTP lipid transfer activity by 39.7% (P = 0.006) and 53.6% (P = 0.0001), respectively, compared with controls. Changes in mRNA and protein levels generally paralleled changes in activity. Interestingly, native swine apo A-IV overexpression also increased MTTP large subunit mRNA, protein levels, and lipid transfer activity in the absence of OA, suggesting a mechanism not mediated by lipid absorption. Overexpression of piglike human apo A-IV significantly increased partitioning of radiolabeled OA from endoplasmic reticulum (ER) membrane to lumen, suggesting increased net transfer of membrane TG to luminal particles. These results suggest that the increased packaging of TG into nascent CMs in the ER lumen, induced by apo A-IV, is associated with upregulation of MTTP activity at the pretranslational level. Thus MTTP is regulated by apo A-IV in a manner to promote increased packaging of TG into the CM core, which may be important in neonatal fat absorption.
Collapse
Affiliation(s)
- Ying Yao
- 1Children's Foundation Research Center at Le Bonheur Children's Medical Center, Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee; and
| | - Song Lu
- 1Children's Foundation Research Center at Le Bonheur Children's Medical Center, Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee; and
| | - Yue Huang
- 1Children's Foundation Research Center at Le Bonheur Children's Medical Center, Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee; and
| | - Casey C. Beeman-Black
- 1Children's Foundation Research Center at Le Bonheur Children's Medical Center, Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee; and
| | - Rena Lu
- 1Children's Foundation Research Center at Le Bonheur Children's Medical Center, Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee; and
| | - Xiaoyue Pan
- 2Departments of Cell Biology and Pediatrics, SUNY Downstate Medical Center, Brooklyn, New York
| | - M. Mahmood Hussain
- 2Departments of Cell Biology and Pediatrics, SUNY Downstate Medical Center, Brooklyn, New York
| | - Dennis D. Black
- 1Children's Foundation Research Center at Le Bonheur Children's Medical Center, Department of Pediatrics, University of Tennessee Health Science Center, Memphis, Tennessee; and
| |
Collapse
|
33
|
Marcil V, Seidman E, Sinnett D, Boudreau F, Gendron FP, Beaulieu JF, Ménard D, Precourt LP, Amre D, Levy E. Modification in oxidative stress, inflammation, and lipoprotein assembly in response to hepatocyte nuclear factor 4alpha knockdown in intestinal epithelial cells. J Biol Chem 2010; 285:40448-60. [PMID: 20871093 DOI: 10.1074/jbc.m110.155358] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Hepatocyte nuclear factor 4α (HNF4α) is a nuclear transcription factor mainly expressed in the liver, intestine, kidney, and pancreas. Many of its hepatic and pancreatic functions have been described, but limited information is available on its role in the gastrointestinal tract. The objectives of this study were to evaluate the anti-inflammatory and antioxidant functions of HNF4α as well as its implication in intestinal lipid transport and metabolism. To this end, the HNF4A gene was knocked down by transfecting Caco-2 cells with a pGFP-V-RS lentiviral vector containing an shRNA against HNF4α. Inactivation of HNF4α in Caco-2 cells resulted in the following: (a) an increase in oxidative stress as demonstrated by the levels of malondialdehyde and conjugated dienes; (b) a reduction in secondary endogenous antioxidants (catalase, glutathione peroxidase, and heme oxygenase-1); (c) a lower protein expression of nuclear factor erythroid 2-related factor that controls the antioxidant response elements-regulated antioxidant enzymes; (d) an accentuation of cellular inflammatory activation as shown by levels of nuclear factor-κB, interleukin-6, interleukin-8, and leukotriene B4; (e) a decrease in the output of high density lipoproteins and of their anti-inflammatory and anti-oxidative components apolipoproteins (apo) A-I and A-IV; (f) a diminution in cellular lipid transport revealed by a lower cellular secretion of chylomicrons and their apoB-48 moiety; and (g) alterations in the transcription factors sterol regulatory element-binding protein 2, peroxisome proliferator-activated receptor α, and liver X receptor α and β. In conclusion, HNF4α appears to play a key role in intestinal lipid metabolism as well as intestinal anti-oxidative and anti-inflammatory defense mechanisms.
Collapse
Affiliation(s)
- Valérie Marcil
- Research Institute, McGill University, Campus MGH, C10.148.6, Montreal H3G 1A4, Quebec
| | | | | | | | | | | | | | | | | | | |
Collapse
|
34
|
Pan X, Zhang Y, Wang L, Hussain MM. Diurnal regulation of MTP and plasma triglyceride by CLOCK is mediated by SHP. Cell Metab 2010; 12:174-86. [PMID: 20674862 PMCID: PMC2925198 DOI: 10.1016/j.cmet.2010.05.014] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Revised: 04/02/2010] [Accepted: 05/26/2010] [Indexed: 12/11/2022]
Abstract
We examined the role of clock genes in the diurnal regulation of plasma triglyceride-rich apolipoprotein B-lipoproteins and their biosynthetic chaperone, microsomal triglyceride transfer protein (MTP). Clock(mt/mt) mice showed sustained hypertriglyceridemia and high MTP expression. CLOCK knockdown activated MTP promoter and reduced small heterodimer partner (SHP, NROB2). CLOCK upregulated SHP by binding to its E box. SHP suppressed MTP expression by binding to the HNF4alpha/LRH-1 at the MTP promoter. Cyclic expression of MTP after serum shock was abrogated by siCLOCK and siSHP. Plasma triglyceride and MTP showed reduced diurnal variations in Shp(-/-) mice. Whereas peaks and nadirs in SHP expression were inversely correlated with those of MTP, these changes were reduced in Clock(mt/mt) mice. Expression of Shp abrogated hypertriglyceridemia in Clock(mt/mt) mice. Together, these studies describe a role of Clock/Shp in the diurnal regulation of MTP and plasma triglyceride and indicate that disruptions in circadian regulation might cause hyperlipidemia.
Collapse
Affiliation(s)
- Xiaoyue Pan
- Department of Cell Biology and Pediatrics, SUNY Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, NY 11203, USA
| | | | | | | |
Collapse
|
35
|
Mirandola S, Bowman D, Hussain MM, Alberti A. Hepatic steatosis in hepatitis C is a storage disease due to HCV interaction with microsomal triglyceride transfer protein (MTP). Nutr Metab (Lond) 2010; 7:13. [PMID: 20178560 PMCID: PMC2838899 DOI: 10.1186/1743-7075-7-13] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Accepted: 02/23/2010] [Indexed: 02/08/2023] Open
Abstract
Liver steatosis is a frequent histological feature in patients chronically infected with hepatitis C virus (HCV). The relationship between HCV and hepatic steatosis seems to be the result of both epigenetic and genetic factors. In vivo and in vitro studies have shown that HCV can alter intrahepatic lipid metabolism by affecting lipid synthesis, oxidative stress, lipid peroxidation, insulin resistance and the assembly and secretion of VLDL. Many studies suggest that HCV-related steatosis might be the result of a direct interaction between the virus and MTP. It has been demonstrated that MTP is critical for the secretion of HCV particles and that inhibition of its lipid transfer activity reduces HCV production. However, higher degrees of hepatic steatosis were found in chronic hepatitis C patients carrying the T allele of MTP -493G/T polymorphism that seems to be associated with increased MTP transcription. We propose here that liver steatosis in hepatitis C could be a storage disease induced by the effects of the virus and of its proteins on the intracellular lipid machinery and on MTP. Available data support the hypothesis that HCV may modulate MTP expression and activity through a number of mechanisms such as inhibition of its activity and transcriptional control. Initial up regulation could favour propagation of HCV while down regulation in chronic phase could cause impairment of triglyceride secretion and excessive lipid accumulation, with abnormal lipid droplets facilitating the "storage" of virus particles for persistent infection.
Collapse
|
36
|
|
37
|
Dai K, Khatun I, Hussain MM. NR2F1 and IRE1beta suppress microsomal triglyceride transfer protein expression and lipoprotein assembly in undifferentiated intestinal epithelial cells. Arterioscler Thromb Vasc Biol 2009; 30:568-74. [PMID: 20007910 DOI: 10.1161/atvbaha.109.198135] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Our aim was to elucidate mechanisms involved in the acquisition of lipid transport properties during enterocyte differentiation. METHODS AND RESULTS We show that lipid mobilization via apolipoprotein B lipoproteins is dependent on the expression of microsomal triglyceride transfer protein (MTP) during differentiation of Caco-2 cells into enterocyte-like cells. Mechanistic studies showed that binding of the nuclear receptor family 2 group F member 1 (NR2F1) to the DR1 element in the MTTP promoter suppresses MTTP expression in undifferentiated cells. During cellular differentiation, NR2F1 expression and its binding to MTTP promoter decline and MTP induction ensues. Moreover, undifferentiated cells express inositol-requiring enzyme 1beta (IRE1beta), a protein that posttranscriptionally degrades MTP mRNA, and its expression substantially decreases during differentiation, contributing to MTP induction. Immunohistochemical studies revealed a significant negative relationship between the expressions of MTP and NR2F1/IRE1beta in undifferentiated and differentiated Caco-2 cells, as well as in crypt-villus and jejunum-colon axes of mouse intestine. CONCLUSIONS We propose that transcriptional and posttranscriptional mechanisms involving NR2F1 and IRE1beta ensure low MTP expression in undifferentiated intestinal cells and avoid apolipoprotein B lipoprotein biosynthesis.
Collapse
Affiliation(s)
- Kezhi Dai
- Department of Anatomy and Cell Biology, SUNY Downstate Medical Center, 450 Clarkson Ave, Brooklyn, NY 11230, USA. , USA
| | | | | |
Collapse
|
38
|
Babeu JP, Darsigny M, Lussier CR, Boudreau F. Hepatocyte nuclear factor 4alpha contributes to an intestinal epithelial phenotype in vitro and plays a partial role in mouse intestinal epithelium differentiation. Am J Physiol Gastrointest Liver Physiol 2009; 297:G124-34. [PMID: 19389805 DOI: 10.1152/ajpgi.90690.2008] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Hepatocyte nuclear factor 4alpha (HNF4alpha) is a regulator of hepatocyte and pancreatic transcription. Hnf4alpha deletion in the mouse is embryonically lethal with severe defects in visceral endoderm formation. It has been concluded in the past that the role of Hnf4alpha in the developing colon was much less important than in the liver. However, the precise role of Hnf4alpha in the homeostasis of the small intestinal epithelium remains unclear. Our aim was to evaluate the potential of Hnf4alpha to support an intestinal epithelial phenotype. First, Hnf4alpha potential to dictate this phenotype was assessed in nonintestinal cell lines in vitro. Forced expression of Hnf4alpha in fibroblasts showed an induction of features normally restricted to epithelial cells. Combinatory expression of Hnf4alpha with specific transcriptional regulators of the intestine resulted in the induction of intestinal epithelial genes in this context. Second, the importance of Hnf4alpha in maintaining the homeostasis of the intestinal epithelium was investigated in mice. Mice conditionally deficient for intestinal Hnf4alpha developed normally throughout adulthood with an epithelium displaying normal morphological and functional structures with minor alterations. Subtle but statistical differences were observed at the proliferation and the cytodifferentiation levels. Hnf4alpha mutant mice displayed an increase in the number of goblet and enteroendocrine cells compared with controls. Given the fundamental role of this transcription factor in other tissues, these findings dispute the crucial role for this regulator in the maintenance of intestinal epithelial cell function at a period of time that follows cytodifferentiation but may suggest a functional role in instructing cells to become specific to the intestinal epithelium.
Collapse
Affiliation(s)
- Jean-Philippe Babeu
- Département d'Anatomie et de Biologie Cellulaire, Université de Sherbrooke,Canadian Institutes of Health Research Team on Digestive Epithelium, Sherbrooke, QC J1H 5N4, Canada
| | | | | | | |
Collapse
|
39
|
Yamaguchi N, Miyamoto S, Ogura Y, Goda T, Suruga K. Hepatocyte nuclear factor-4alpha regulates human cellular retinol-binding protein type II gene expression in intestinal cells. Am J Physiol Gastrointest Liver Physiol 2009; 296:G524-33. [PMID: 19147806 DOI: 10.1152/ajpgi.90469.2008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Cellular retinol-binding protein type II (CRBPII) is abundantly expressed in the small intestinal enterocytes of many vertebrates and plays important physiological roles in intestinal absorption, transport, and metabolism of vitamin A. In the present study, we investigated regulation of human CRBPII gene expression using human intestinal Caco-2 BBe cells. We found that the human CRBPII gene contained a direct repeat 1 (DR-1)-like nuclear receptor response element in the proximal promoter region and that endogenous hepatocyte nuclear factor-4alpha (HNF-4alpha) was a major transcription factor binding to the DR-1-like element. Cotransfection of HNF-4alpha expression vector transactivated the human CRBPII gene promoter activity, whereas mutation of the DR-1-like element abolished the promoter activity. Stably transfected Caco-2 BBe cells overexpressing HNF-4alpha significantly increased endogenous CRBPII gene expression and retinyl ester synthesis. Reduction of HNF-4alpha protein levels by HNF-4alpha small interference RNA decreased CRBPII gene expression. Caco-2 BBe cells treated with phorbol 12-myristate 13-acetate, a protein kinase C activator, decreased nuclear HNF-4alpha protein level and binding activity to the human CRBPII gene DR-1-like element, as well as CRBPII gene expression. Moreover, nuclear HNF-4alpha protein levels, HNF-4alpha protein binding to human CRBPII DR-1-like elements, and CRBPII gene expression level were coordinately increased during Caco-2 BBe cell differentiation. These results suggest that HNF-4alpha is an important transcriptional factor that regulates human CRBPII gene expression and provide the possibility for a novel function of HNF-4alpha in the regulation of human intestinal vitamin A absorption and metabolism.
Collapse
Affiliation(s)
- Noriaki Yamaguchi
- Graduate School of Human Health Sciences, University of Nagasaki, 1-1-1 Manabino, Nagayo-cho, Nishisonogi-gun, Nagasaki 851-2195, Japan
| | | | | | | | | |
Collapse
|
40
|
Abstract
Very low-density lipoproteins (VLDL) are triglyceride-rich particles. VLDL is synthesized in hepatocytes and secreted from the liver in a pathway that is tightly regulated by insulin. Hepatic VLDL production is stimulated in response to reduced insulin action, resulting in increased release of VLDL into the blood under fasting conditions. Circulating VLDL serves as a vehicle for transporting lipids to peripheral tissues for energy homeostasis. Conversely, hepatic VLDL production is suppressed in response to increased insulin release after meals. This effect is critical for preventing prolonged excursion of postprandial plasma lipid profiles in normal individuals. In subjects with obesity and type 2 diabetes, the ability of insulin to regulate VLDL production becomes impaired due to insulin resistance in the liver, resulting in excessive VLDL secretion and accumulation of triglyceride-rich particles in the blood. Such abnormality in lipid metabolism characterizes the pathogenesis of hypertriglyceridemia and accounts for increased risk of coronary artery disease in obesity and type 2 diabetes. Nevertheless, the molecular basis that links insulin resistance to VLDL overproduction remains poorly understood. Our recent studies illustrate that the forkhead transcription factor FoxO1 acts in the liver to integrate hepatic insulin action to VLDL production. Augmented FoxO1 activity in insulin resistant livers promotes hepatic VLDL overproduction and predisposes to the development of hypertriglyceridemia. These new findings raise an important question: Is FoxO1 a therapeutic target for ameliorating hypertriglyceridemia? Here we discuss this question in the context of recent advances toward our understanding of the pathophysiology of hypertriglyceridemia.
Collapse
Affiliation(s)
- Adama Kamagate
- Department of Pediatrics, Division of Immunogenetics, Rangos Research Center, Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA
| | | |
Collapse
|
41
|
Hussain MM, Rava P, Pan X, Dai K, Dougan SK, Iqbal J, Lazare F, Khatun I. Microsomal triglyceride transfer protein in plasma and cellular lipid metabolism. Curr Opin Lipidol 2008; 19:277-84. [PMID: 18460919 DOI: 10.1097/mol.0b013e3282feea85] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
PURPOSE OF REVIEW This review summarizes recent advances about the role of microsomal triglyceride transfer protein in plasma and tissue lipid homeostasis. RECENT FINDINGS Microsomal triglyceride transfer protein emerged as a phospholipid transfer protein and acquired triacylglycerol transfer activity during evolution from invertebrates to vertebrates. These activities are proposed to participate in 'nucleation' and 'desorption' steps during the biosynthesis of primordial apoB-containing lipoproteins. Microsomal triglyceride transfer protein also transfers phospholipids to the glycolipid antigen presentation molecule CD1d. Under physiologic conditions, plasma apoB-containing lipoproteins and microsomal triglyceride transfer protein expression exhibit diurnal variations synchronized by food and light. Microsomal triglyceride transfer protein is regulated at the transcriptional level. HNF4alpha is critical for its transcription. Other transcription factors along with coactivators and corepressors modulate microsomal triglyceride transfer protein expression. Reductions in microsomal triglyceride transfer protein mRNA and activity are related to steatosis in HCV-3 infected patients. CCl4 induces steatosis by enhancing proteasomal degradation of microsomal triglyceride transfer protein and can be partially avoided by inhibiting this degradation. Chemical antagonists cause hepatosteatosis, but this was not seen in the absence of fatty acid binding protein. SUMMARY Microsomal triglyceride transfer protein is a target to lower plasma lipids and to reduce inflammation in certain immune disorders. More knowledge is required, however, regarding its regulation and its role in the biosynthesis of apoB-containing lipoproteins and CD1d.
Collapse
Affiliation(s)
- M Mahmood Hussain
- Department of Anatomy and Cell Biology, SUNY Downstate Medical Center, Brooklyn, New York 11203, USA.
| | | | | | | | | | | | | | | |
Collapse
|
42
|
Black MH, Fingerlin TE, Allayee H, Zhang W, Xiang AH, Trigo E, Hartiala J, Lehtinen AB, Haffner SM, Bergman RN, McEachin RC, Kjos SL, Lawrence JM, Buchanan TA, Watanabe RM. Evidence of interaction between PPARG2 and HNF4A contributing to variation in insulin sensitivity in Mexican Americans. Diabetes 2008; 57:1048-56. [PMID: 18162503 PMCID: PMC4447520 DOI: 10.2337/db07-0848] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE We hypothesized that interaction between PPARG2 Pro12Ala and variants in the promoter region of HNF4A are associated with type 2 diabetes-related quantitative traits in Mexican-American families of a proband with previous gestational diabetes. RESEARCH DESIGN AND METHODS The BetaGene project genotyped PPARG2 Pro12Ala and nine HNF4A single nucleotide polymorphisms (SNPs) in 473 individuals in 89 families. Members of the proband generation had fasting glucose <126 mg/dl and were phenotyped by oral and intravenous glucose tolerance tests. RESULTS Neither PPARG2 Pro12Ala nor any of the nine HNF4A SNPs were independently associated with type 2 diabetes-related quantitative traits. However, the interaction between PPARG2 Pro12Ala and HNF4A rs2144908 was significantly associated with both insulin sensitivity (S(I)) (Bonferroni P = 0.0006) and 2-h insulin (Bonferroni P = 0.039). Subjects with at least one PPARG2 Ala allele and homozygous for the HNF4A rs2144908 A allele had 40% higher S(I) compared with individuals with at least one G allele. S(I) did not vary by rs2144908 genotype among PPARG2 Pro/Pro. The interaction result for S(I) was replicated by the Insulin Resistance Atherosclerosis Family Study (P = 0.018) in their San Antonio sample (n = 484) where subjects with at least one PPARG2 Ala allele and homozygous for the HNF4A rs2144908 A allele had a 29% higher S(I) compared with individuals with at least one G allele. However, the interaction was not replicated in their San Luis Valley sample (n = 496; P = 0.401). CONCLUSIONS Together, these results suggest that variation in PPARG2 and HNF4A may interact to regulate insulin sensitivity in Mexican Americans at risk for type 2 diabetes.
Collapse
Affiliation(s)
- Mary Helen Black
- Department of Preventive Medicine, Division of Biostatistics, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Tasha E. Fingerlin
- Department of Preventive Medicine and Biometrics, University of Colorado at Denver and Health Sciences Center, Denver, Colorado
| | - Hooman Allayee
- Department of Preventive Medicine, Division of Biostatistics, Keck School of Medicine, University of Southern California, Los Angeles, California
- Institute for Genetic Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Weiming Zhang
- Department of Preventive Medicine and Biometrics, University of Colorado at Denver and Health Sciences Center, Denver, Colorado
| | - Anny H. Xiang
- Department of Preventive Medicine, Division of Biostatistics, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Enrique Trigo
- Department of Medicine, Division of Diabetes and Endocrinology, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Jaana Hartiala
- Department of Preventive Medicine, Division of Biostatistics, Keck School of Medicine, University of Southern California, Los Angeles, California
- Institute for Genetic Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Allison B. Lehtinen
- Department of Biochemistry and Center for Human Genomics, Wake Forest University School of Medicine, Winston-Salem, North Carolina
| | - Steven M. Haffner
- Department of Medicine, Division of Clinical Epidemiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Richard N. Bergman
- Department of Physiology and Biophysics, Keck School of Medicine of University of Southern California, Los Angeles, California
| | - Richard C. McEachin
- Department of Psychiatry, University of Michigan Medical School, Ann Arbor, Michigan
| | - Siri L. Kjos
- Department of Obstetrics and Gynecology, Harbor-UCLA Medical Center, Los Angeles, California
| | - Jean M. Lawrence
- Research and Evaluation, Kaiser Permanente Southern California, Pasadena, California
| | - Thomas A. Buchanan
- Department of Medicine, Division of Diabetes and Endocrinology, Keck School of Medicine, University of Southern California, Los Angeles, California
- Department of Physiology and Biophysics, Keck School of Medicine of University of Southern California, Los Angeles, California
| | - Richard M. Watanabe
- Department of Preventive Medicine, Division of Biostatistics, Keck School of Medicine, University of Southern California, Los Angeles, California
- Department of Physiology and Biophysics, Keck School of Medicine of University of Southern California, Los Angeles, California
| |
Collapse
|
43
|
Leng S, Lu S, Yao Y, Kan Z, Morris GS, Stair BR, Cherny MA, Black DD. Hepatocyte nuclear factor-4 mediates apolipoprotein A-IV transcriptional regulation by fatty acid in newborn swine enterocytes. Am J Physiol Gastrointest Liver Physiol 2007; 293:G475-83. [PMID: 17556588 DOI: 10.1152/ajpgi.00072.2007] [Citation(s) in RCA: 20] [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: 01/31/2023]
Abstract
Hepatocyte nuclear factor-4alpha (HNF-4alpha) regulates transcription of several genes involved in lipid metabolism, including that of apolipoprotein (apo) A-IV, which is tightly regulated by lipid absorption and enhances enterocyte chylomicron secretion. Studies were performed to define the role of HNF-4alpha in the regulation of apo A-IV gene transcription by dietary fatty acid in neonatal swine small intestine. HNF-4alpha mRNA was expressed in liver > intestine > kidney in suckling, weanling, and weaned pigs. Jejunal HNF-4alpha mRNA and protein and apo A-IV and swine microsomal triglyceride transfer protein (MTP) large subunit mRNA expression were induced in parallel in 2-day-old swine by a 24-h high-fat intraduodenal infusion. In IPEC-1 cells, incubation with oleic acid (OA) resulted in coordinate induction of both HNF-4alpha, apo A-IV, and MTP mRNA, similar to that observed in vivo. When HNF-4alpha expression was driven by doxycycline by using the TET-On system in the absence of OA to observe the effect of HNF-4alpha directly on apo A-IV and MTP mRNA levels in the absence of other factors that might be concomitantly induced by fatty acid absorption, apo A-IV and MTP expression were increased. In luciferase reporter gene assays in IPEC-1 cells using apo A-IV/C-III intergenic region constructs, TET-On-regulated HNF-4alpha expression without OA increased luciferase activity, and incubation with OA did not further increase activity. These data suggest that acute induction of the apo A-IV and MTP genes by dietary lipid in newborn intestine occurs, at least in part, via ligand-independent transactivation by HNF-4alpha that is itself induced by a lipid-mediated mechanism.
Collapse
Affiliation(s)
- Shuangying Leng
- Children's Foundation Research Center of Memphis, Le Bonheur Children's Medical Center, Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN 38103, USA
| | | | | | | | | | | | | | | |
Collapse
|
44
|
Blasiole DA, Davis RA, Attie AD. The physiological and molecular regulation of lipoprotein assembly and secretion. MOLECULAR BIOSYSTEMS 2007; 3:608-19. [PMID: 17700861 DOI: 10.1039/b700706j] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Triglycerides are insoluble in water and yet are transported at milligram per millilitre concentrations in the bloodstream. This is made possible by the ability of the liver and intestine to assemble lipid-protein emulsions (i.e. lipoproteins), which transport hydrophobic molecules. The assembly of triglyceride-rich lipoproteins requires the coordination of protein and lipid synthesis, which occurs on the cytoplasmic surface of the endoplasmic reticulum (ER), and their concerted assembly and translocation into the luminal ER secretory pathway as nascent lipoprotein particles. The availability of lipid substrate for triglyceride production and the machinery for lipoprotein assembly are highly sensitive to nutritional, hormonal, and genetic modulation. Disorders in lipid metabolism or an imbalance between lipogenesis and lipoprotein assembly can lead to hyperlipidemia and/or hepatic steatosis. We selectively review recently-identified machinery, such as transcription factors and nuclear hormone receptors, which provide new clues to the regulation of lipoprotein secretion.
Collapse
Affiliation(s)
- Daniel A Blasiole
- Department of Biochemistry, University of Wisconsin-Madison, 433 Babcock Dr., Madison, WI 53706, USA
| | | | | |
Collapse
|
45
|
Pan X, Hussain MM. Diurnal regulation of microsomal triglyceride transfer protein and plasma lipid levels. J Biol Chem 2007; 282:24707-19. [PMID: 17575276 DOI: 10.1074/jbc.m701305200] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Plasma lipids are maintained within a narrow physiologic range and exhibit circadian rhythmicity. Plasma triglyceride and cholesterol levels were high in the night due to changes in apolipoprotein B-lipoproteins in ad libitum fed rats and mice maintained in a 12-h photoperiod. Absorption of [(3)H]triolein or [(3)H]cholesterol was higher at 2400 h than at 1200 h, indicating that intestinal lipoprotein production shows diurnal variation. Moreover, intestinal microsomal triglyceride transfer protein (MTP) activity, protein, mRNA, and gene transcription showed diurnal variations and were high at 2400 h. Similar to the small intestine, hepatic MTP activity, protein, and mRNA levels also changed significantly within a day. MTP was induced in fasted animals soon after refeeding. When mice were subjected to restricted feeding, MTP expression was high at the expected time of food availability. In contrast, extended exposures to light and dark completely abolished rhythmicity in MTP expression and plasma lipid levels. These studies show that MTP expression and plasma lipid undergo diurnal regulation and exhibit peaks and nadirs at similar times and suggest that diurnal modulation of MTP is a major determinant of daily changes in plasma lipids. Furthermore, environmental factors, such as food and light, play an important role in MTP regulation.
Collapse
Affiliation(s)
- Xiaoyue Pan
- Department of Anatomy and Cell Biology, State University of New York Downstate Medical Center, Brooklyn, New York 11203, USA
| | | |
Collapse
|
46
|
Klapper M, Böhme M, Nitz I, Döring F. The human intestinal fatty acid binding protein (hFABP2) gene is regulated by HNF-4alpha. Biochem Biophys Res Commun 2007; 356:147-52. [PMID: 17343826 DOI: 10.1016/j.bbrc.2007.02.091] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2007] [Accepted: 02/16/2007] [Indexed: 10/23/2022]
Abstract
The cytosolic human intestinal fatty acid binding protein (hFABP2) is proposed to be involved in intestinal absorption of long-chain fatty acids. The aim of this study was to investigate the regulation of hFABP2 by the endodermal hepatocyte nuclear factor 4alpha (HNF-4alpha), involved in regulation of genes of fatty acid metabolism and differentiation. Electromobility shift assays demonstrated that HNF-4alpha binds at position -324 to -336 within the hFABP2 promoter. Mutation of this HNF-4 binding site abolished the luciferase reporter activity of hFABP2 in postconfluent Caco-2 cells. In HeLa cells, this mutation reduced the activation of the hFABP2 promoter by HNF-4alpha by about 50%. Thus, binding element at position -336/-324 essentially determines the transcriptional activity of promoter and may be important in control of hFABP2 expression by dietary lipids and differentiation. Studying genotype interactions of hFABP2 and HNF-4alpha, that are both candidate genes for diabetes type 2, may be a powerful approach.
Collapse
Affiliation(s)
- Maja Klapper
- Molecular Nutrition, Institute of Human Nutrition and Food Science, Christian-Albrechts-University of Kiel, Heinrich-Hecht-Platz 10, D-24118 Kiel, Germany.
| | | | | | | |
Collapse
|
47
|
Dougan SK, Rava P, Hussain MM, Blumberg RS. MTP regulated by an alternate promoter is essential for NKT cell development. ACTA ACUST UNITED AC 2007; 204:533-45. [PMID: 17312007 PMCID: PMC2137905 DOI: 10.1084/jem.20062006] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Microsomal triglyceride transfer protein (MTP), an endoplasmic reticulum lipid transfer protein critical for apolipoprotein B (apoB) secretion, regulates CD1d antigen presentation. We identified MTP variant 1 (MTPv1), a novel splice variant of mouse MTP, by polymerase chain reaction and Northern analysis in non-apoB-secreting tissues, including thymocytes and antigen-presenting cells (APCs). Edman degradation of MTPv1 isolated from transfected cells revealed three unique residues; however, recombinant MTP and MTPv1 had an equivalent protein disulfide isomerase association, subcellular localization, triglyceride transfer, phospholipid transfer, response to inhibitors, and ability to support apoB secretion. MTP and MTPv1 efficiently transferred phosphatidylethanolamine to CD1d in vitro. NKT cells fail to develop in fetal thymic organ culture (FTOC) treated with MTP antagonists. MTP-inhibited FTOCs produced negligible numbers of CD1d tetramer-positive cells and exhibited marked defects in IL-4 production upon stimulation with anti-CD3 or alpha-galactosylceramide-pulsed APCs. CD1d expression on CD4(+)CD8(+) FTOC cells was unaffected by MTP inhibition. Thus, our results demonstrate that MTPv1 in thymocytes is critical to NKT cell development. We hypothesize that, when MTP is inactive, CD1d traffics to the cell surface and presents no lipid or a lipid that is incapable of mediating NKT cell selection and/or is refractory to lysosomal editing.
Collapse
Affiliation(s)
- Stephanie K Dougan
- Gastroenterology Division, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA
| | | | | | | |
Collapse
|
48
|
Rubin D, Schneider-Muntau A, Klapper M, Nitz I, Helwig U, Fölsch UR, Schrezenmeir J, Döring F. Functional analysis of promoter variants in the microsomal triglyceride transfer protein (MTTP) gene. Hum Mutat 2007; 29:123-9. [PMID: 17854051 DOI: 10.1002/humu.20615] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The microsomal triglyceride transfer protein (MTTP) is required for the assembly and secretion of apolipoprotein B (apoB)-containing lipoproteins from the intestine and liver. According to this function, polymorphic sites in the MTTP gene showed associations to low-density lipoprotein (LDL) cholesterol and related traits of the metabolic syndrome. Here we studied the functional impact of common MTTP promoter polymorphisms rs1800804:T>C (-164T>C), rs1800803:A>T (-400A>T), and rs1800591:G>T (-493G>T) using gene-reporter assays in intestinal Caco-2 and liver Huh-7 cells. Significant results were obtained in Huh-7 cells. The common MTTP promoter haplotype -164T/-400A/-493G showed about two-fold lower activity than the rare haplotype -164C/-400T/-493T. MTTP promoter mutant constructs -164T/-400A/-493T and -164T/-400T/-493T exhibited similar activity than the common haplotype. Activities of mutants -164C/-400A/-493G and -164C/-400A/-493T resembled the rare MTTP promoter haplotype. Electrophoretic mobility shift assays (EMSAs) revealed higher binding capacity of the transcriptional factor Sterol regulatory element binding protein1a (SREBP1a) to the -164T probe in comparison to the -164C probe. In conclusion, our study indicates that the polymorphism -164T>C mediates different activities of common MTTP promoter haplotypes via SREBP1a. This suggested that the already described SREBP-dependent modulation of MTTP expression by diet is more effective in -164T than in -164C carriers.
Collapse
Affiliation(s)
- Diana Rubin
- Institute of Physiology and Biochemistry of Nutrition, Federal Research Center for Nutrition and Food, Kiel, Germany.
| | | | | | | | | | | | | | | |
Collapse
|
49
|
Li LO, Mashek DG, An J, Doughman SD, Newgard CB, Coleman RA. Overexpression of rat long chain acyl-coa synthetase 1 alters fatty acid metabolism in rat primary hepatocytes. J Biol Chem 2006; 281:37246-55. [PMID: 17028193 DOI: 10.1074/jbc.m604427200] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Long chain acyl-CoA synthetases (ACSL) activate fatty acids (FA) and provide substrates for both anabolic and catabolic pathways. We have hypothesized that each of the five ACSL isoforms partitions FA toward specific downstream pathways. Acsl1 mRNA is increased in cells under both lipogenic and oxidative conditions. To elucidate the role of ACSL1 in hepatic lipid metabolism, we overexpressed an Acsl1 adenovirus construct (Ad-Acsl1) in rat primary hepatocytes. Ad-ACSL1, located on the endoplasmic reticulum but not on mitochondria or plasma membrane, increased ACS specific activity 3.7-fold. With 100 or 750 mum [1-(14)C]oleate, Ad-Acsl1 increased oleate incorporation into diacylglycerol and phospholipids, particularly phosphatidylethanolamine and phosphatidylinositol, and decreased incorporation into cholesterol esters and secreted triacylglycerol. Ad-Acsl1 did not alter oleate incorporation into triacylglycerol, beta-oxidation products, or total amount of FA metabolized. In pulse-chase experiments to examine the effects of Ad-Acsl1 on lipid turnover, more labeled triacylglycerol and phospholipid, but less labeled diacylglycerol, remained in Ad-Acsl1 cells, suggesting that ACSL1 increased reacylation of hydrolyzed oleate derived from triacylglycerol and diacylglycerol. In addition, less hydrolyzed oleate was used for cholesterol ester synthesis and beta-oxidation. The increase in [1,2,3-(3)H]glycerol incorporation into diacylglycerol and phospholipid was similar to the increase with [(14)C]oleate labeling suggesting that ACSL1 increased de novo synthesis. Labeling Ad-Acsl1 cells with [(14)C]acetate increased triacylglycerol synthesis but did not channel endogenous FA away from cholesterol ester synthesis. Thus, consistent with the hypothesis that individual ACSLs partition FA, Ad-Acsl1 increased FA reacylation and channeled FA toward diacylglycerol and phospholipid synthesis and away from cholesterol ester synthesis.
Collapse
Affiliation(s)
- Lei O Li
- Department of Nutrition, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | | | | | | | | | | |
Collapse
|
50
|
Dubey P, Cheema SK. Molecular mechanisms involved in the regulation of lipid and lipoprotein metabolism by fish oil. ACTA ACUST UNITED AC 2006. [DOI: 10.2217/17460875.1.5.559] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
|