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Chen Z, Shao W, Li Y, Zhang X, Geng Y, Ma X, Tao B, Ma Y, Yi C, Zhang B, Zhang R, Lin J, Chen J. Inhibition of PCSK9 prevents and alleviates cholesterol gallstones through PPARα-mediated CYP7A1 activation. Metabolism 2024; 152:155774. [PMID: 38191052 DOI: 10.1016/j.metabol.2023.155774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Revised: 12/28/2023] [Accepted: 12/31/2023] [Indexed: 01/10/2024]
Abstract
BACKGROUND & AIMS Dysregulated cholesterol metabolism is the major factor responsible for cholesterol gallstones (CGS). Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a critical role in cholesterol homeostasis and its inhibitors secure approval for treating various cholesterol metabolic disorders such as hypercholesterolemia and cardiovascular diseases, but its role in CGS remains unclear. Our study aims to clarify mechanisms by which PCSK9 promotes CGS formation and explore the application of the PCSK9 inhibitor, alirocumab, in preventing and treating CGS. APPROACH & RESULTS The expressions of PCSK9 were notably increased in CGS patients' serum, bile, and liver tissues compared to those without gallstones. Moreover, among CGS patients, hepatic PCSK9 was positively correlated with hepatic cholesterol and negatively correlated with hepatic bile acids (BAs), suggesting PCSK9 was involved in disrupted hepatic cholesterol metabolism related to CGS. Mechanistically, in vitro experiments demonstrated that inhibition of PCSK9 enhanced nuclear expression of PPARα by diminishing its lysosomal degradation and subsequently activated CYP7A1 transcription. Finally, inhibition of PCSK9 prevented CGS formation and dissolved the existing stones in CGS mice by elevating the conversion of cholesterol into BAs through PPARα-mediated CYP7A1 activation. Additionally, serum PCSK9 level may function as a prognostic signature to evaluate the therapeutic efficacy of PCSK9 inhibitors. CONCLUSIONS Inhibition of PCSK9 exerts preventive and therapeutic effects on CGS by activating PPARα-mediated CYP7A1 expression and facilitating the conversion of cholesterol into BAs, which highlights the potential of PCSK9 inhibition as a promising candidate for preventing and treating CGS in clinical applications. IMPACT AND IMPLICATIONS PCSK9 plays a pivotal role in cholesterol metabolism and its inhibitors are approved for clinical use in cardiovascular diseases. Our study observes inhibition of PCSK9 prevents and dissolves CGS by activating PPARα-mediated CYP7A1 expression and facilitating the conversion of cholesterol into BAs. Mechanistically, PCSK9 inhibition enhanced the nuclear expression of PPARα by diminishing its lysosomal degradation and subsequently activated CYP7A1 transcription. Our study sheds light on the new function and mechanism of PCSK9 in CGS, providing a novel preventive and therapeutic target with potential clinical applications.
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Affiliation(s)
- Zhenmei Chen
- Hepatobiliary Surgery, Department of General Surgery, Huashan Hospital, Fudan University, 12 Urumqi Road, Shanghai 200040, China; Shanghai Institute of Infectious Disease and Biosecurity, Huashan Hospital, Fudan University, 12 Urumqi Road, Shanghai 200040, China
| | - Weiqing Shao
- Hepatobiliary Surgery, Department of General Surgery, Huashan Hospital, Fudan University, 12 Urumqi Road, Shanghai 200040, China
| | - Yitong Li
- Hepatobiliary Surgery, Department of General Surgery, Huashan Hospital, Fudan University, 12 Urumqi Road, Shanghai 200040, China
| | - Xiandi Zhang
- Department of Ultrasound, Huashan Hospital, Fudan University, 12 Urumqi Road, Shanghai 200040, China
| | - Yan Geng
- Hepatobiliary Surgery, Department of General Surgery, Huashan Hospital, Fudan University, 12 Urumqi Road, Shanghai 200040, China
| | - Xiaochen Ma
- Hepatobiliary Surgery, Department of General Surgery, Huashan Hospital, Fudan University, 12 Urumqi Road, Shanghai 200040, China
| | - Baorui Tao
- Hepatobiliary Surgery, Department of General Surgery, Huashan Hospital, Fudan University, 12 Urumqi Road, Shanghai 200040, China
| | - Yue Ma
- Hepatobiliary Surgery, Department of General Surgery, Huashan Hospital, Fudan University, 12 Urumqi Road, Shanghai 200040, China
| | - Chenhe Yi
- Hepatobiliary Surgery, Department of General Surgery, Huashan Hospital, Fudan University, 12 Urumqi Road, Shanghai 200040, China
| | - Bo Zhang
- Hepatobiliary Surgery, Department of General Surgery, Huashan Hospital, Fudan University, 12 Urumqi Road, Shanghai 200040, China
| | - Rui Zhang
- Hepatobiliary Surgery, Department of General Surgery, Huashan Hospital, Fudan University, 12 Urumqi Road, Shanghai 200040, China
| | - Jing Lin
- Hepatobiliary Surgery, Department of General Surgery, Huashan Hospital, Fudan University, 12 Urumqi Road, Shanghai 200040, China.
| | - Jinhong Chen
- Hepatobiliary Surgery, Department of General Surgery, Huashan Hospital, Fudan University, 12 Urumqi Road, Shanghai 200040, China.
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2
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Jin L, Dang H, Wu J, Yuan L, Chen X, Yao J. Supplementation of Weizmannia coagulans BC2000 and Ellagic Acid Inhibits High-Fat-Induced Hypercholesterolemia by Promoting Liver Primary Bile Acid Biosynthesis and Intestinal Cholesterol Excretion in Mice. Microorganisms 2023; 11:microorganisms11020264. [PMID: 36838229 PMCID: PMC9964488 DOI: 10.3390/microorganisms11020264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 01/13/2023] [Accepted: 01/17/2023] [Indexed: 01/20/2023] Open
Abstract
The probiotic Weizmannia coagulans (W. coagulans) BC2000 can increase the abundance of intestinal transforming ellagic acid (EA) bacteria and inhibit metabolic disorders caused by hyperlipidemia by activating liver autophagy. This study aimed to investigate the inhibitory effects of W. coagulans BC2000 and EA on hyperlipidemia-induced cholesterol metabolism disorders. C57BL/6J mice (n = 10 in each group) were fed a low-fat diet, high-fat diet (HFD), HFD supplemented with EA, HFD supplemented with EA and W. coagulans BC77, HFD supplemented with EA, and W. coagulans BC2000. EA and W. coagulans BC2000 supplementation prevented HFD-induced hypercholesterolemia and promoted fecal cholesterol excretion. Transcriptome analysis showed that primary bile acid biosynthesis in the liver was significantly activated by EA and W. coagulans BC2000 treatments. EA and W. coagulans BC2000 treatment also significantly increased the intestinal Eggerthellaceae abundance and the liver EA metabolites, iso-urolithin A, Urolithin A, and Urolithin B. Therefore, W. coagulans BC2000 supplementation promoted the intestinal transformation of EA, which led to the upregulation of liver bile synthesis, thus preventing hypercholesterolemia.
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Affiliation(s)
- Long Jin
- Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
- Science Island Branch, Graduate School of University of Science and Technology of China, Hefei 230026, China
- Probiotics Institute, Hefei 230031, China
| | - Hongyang Dang
- College Life Science & Technology, Xinjiang University, Urumqi 830046, China
- Institute of Nutrition and Health, Qingdao University, Qingdao 266021, China
| | - Jinyong Wu
- Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
| | - Lixia Yuan
- Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
| | - Xiangsong Chen
- Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
- Correspondence: (X.C.); (J.Y.)
| | - Jianming Yao
- Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
- Science Island Branch, Graduate School of University of Science and Technology of China, Hefei 230026, China
- Correspondence: (X.C.); (J.Y.)
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3
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Banno A, Yamamoto M, Mijiti M, Takeuchi A, Ye Y, Oda N, Nishino N, Ebihara A, Nagaoka S. The physiological blood concentration of phenylalanine-proline can ameliorate cholesterol metabolism in HepG2 cells. Biosci Biotechnol Biochem 2022; 87:90-98. [PMID: 36352466 DOI: 10.1093/bbb/zbac167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 10/13/2022] [Indexed: 11/11/2022]
Abstract
We have previously reported that the dipeptide Phe-Pro affects lipid metabolism in vivo and in vitro, but very little is known regarding the mechanism of action of Phe-Pro after it is absorbed by the intestines via PepT1. In this study, we administered a single oral dose of Phe-Pro to rats and quantified its concentration in the portal plasma using LC-TOF/MS analysis. Additionally, the physiological blood concentration of Phe-Pro was added to the lipid accumulation model of HepG2 cells to decrease intracellular cholesterol and increase the expression of CYP7A1 and PPARα mRNA levels. Moreover, we analyzed the binding of PPARα and Phe-Pro using AlphaFold2. We found that Phe-Pro is a ligand for PPARα. To the best of our knowledge, this is the first study that shows Phe-Pro to be present in the portal plasma. We found for the first time that Phe-Pro ameliorated cholesterol metabolism in HepG2 cells.
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Affiliation(s)
- Arata Banno
- Department of Applied Life Science, Faculty of Applied Biological Sciences, Gifu University, Gifu, Japan
| | - Mako Yamamoto
- Department of Applied Life Science, Faculty of Applied Biological Sciences, Gifu University, Gifu, Japan
| | - Maihemuti Mijiti
- Department of Applied Life Science, Faculty of Applied Biological Sciences, Gifu University, Gifu, Japan
| | - Asahi Takeuchi
- Department of Applied Life Science, Faculty of Applied Biological Sciences, Gifu University, Gifu, Japan
| | - Yuyang Ye
- Department of Applied Life Science, Faculty of Applied Biological Sciences, Gifu University, Gifu, Japan
| | - Natsuki Oda
- Department of Applied Life Science, Faculty of Applied Biological Sciences, Gifu University, Gifu, Japan
| | - Nanami Nishino
- Department of Applied Life Science, Faculty of Applied Biological Sciences, Gifu University, Gifu, Japan
| | - Akio Ebihara
- Department of Applied Life Science, Faculty of Applied Biological Sciences, Gifu University, Gifu, Japan
| | - Satoshi Nagaoka
- Department of Applied Life Science, Faculty of Applied Biological Sciences, Gifu University, Gifu, Japan
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4
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Impact of Liver Inflammation on Bile Acid Side Chain Shortening and Amidation. Cells 2022; 11:cells11243983. [PMID: 36552746 PMCID: PMC9777420 DOI: 10.3390/cells11243983] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 12/03/2022] [Accepted: 12/05/2022] [Indexed: 12/13/2022] Open
Abstract
Bile acid (BA) synthesis from cholesterol by hepatocytes is inhibited by inflammatory cytokines. Whether liver inflammation also affects BA side chain shortening and conjugation was investigated. In human liver cell lines (IHH, HepG2, and HepaRG), agonists of nuclear receptors including the farnesoid X receptor (FXR), liver X receptor (LXR), and peroxisome proliferator-activated receptors (PPARs) did not affect the expression of BA-related peroxisomal enzymes. In contrast, hepatocyte nuclear factor 4α (HNF4α) inhibition down-regulated acyl-CoA oxidase 2 (ACOX2). ACOX2 was repressed by fibroblast growth factor 19 (FGF19), which was prevented by extracellular signal-regulated kinase (ERK) pathway inhibition. These changes were paralleled by altered BA synthesis (HPLC-MS/MS). Cytokines able to down-regulate cholesterol-7α-hydroxylase (CYP7A1) had little effect on peroxisomal enzymes involved in BA synthesis except for ACOX2 and bile acid-CoA:amino acid N-acyltransferase (BAAT), which were down-regulated, mainly by oncostatin M (OSM). This effect was prevented by Janus kinase (JAK) inhibition, which restored BA side chain shortening and conjugation. The binding of OSM to the extracellular matrix accounted for a persistent effect after culture medium replacement. In silico analysis of four databases (n = 201) and a validation cohort (n = 90) revealed an inverse relationship between liver inflammation and ACOX2/BAAT expression which was associated with changes in HNF4α levels. In conclusion, BA side chain shortening and conjugation are inhibited by inflammatory effectors. However, other mechanisms involved in BA homeostasis counterbalance any significant impact on the serum BA profile.
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5
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Luo Z, Li M, Yang J, Li J, Zhang Y, Liu F, El-Omar E, Han L, Bian J, Gong L, Wang M. Ferulic acid attenuates high-fat diet-induced hypercholesterolemia by activating classic bile acid synthesis pathway. Front Nutr 2022; 9:976638. [PMID: 36211528 PMCID: PMC9536491 DOI: 10.3389/fnut.2022.976638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 08/30/2022] [Indexed: 12/03/2022] Open
Abstract
Ferulic acid (FA), a natural phenolic phytochemical abundantly present in whole grains, displays promising therapeutic effects on hypercholesterolemia while its underlying mechanism not fully elucidated. This study aimed to investigate the cholesterol-lowering effect of FA in high-fat diet (HFD)-fed mice and its potential molecular mechanism. FA supplementation alleviated HFD-induced hypercholesterolemia (–13.2%, p < 0.05), along with increased excretion of bile acids (BAs) in feces (37.0%, p < 0.05). Mechanism studies showed that FA activated the expression of cholesterol 7α hydroxylase (CYP7A1), a rate-limiting enzyme in BA biosynthesis in the liver, which increased the BAs biosynthesis from cholesterol. Surprisingly, increased excretion of BAs in feces is a consequence, not a cause, of CYP7A1 activation. Furthermore, enterohepatic farnesoid X receptor (FXR) signaling is not involved in the activation of hepatic CYP7A1 by FA. In conclusion, FA activates CYP7A1 through non-FXR signaling, which on the one hand effectively prevents hypercholesterolemia, and on the other hand leads to secondary BAs elevation in plasma. The latter may be the key to the anti-obesity and hypoglycemic effects of FA.
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Affiliation(s)
- Zhixin Luo
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
| | - Mengqian Li
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
| | - Jiachuan Yang
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
| | - Jia Li
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
| | - Yao Zhang
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
| | - Fang Liu
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
| | - Emad El-Omar
- Microbiome Research Centre, St George and Sutherland Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - Lin Han
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
- *Correspondence: Lin Han,
| | - Ji Bian
- Kolling Institute, Sydney Medical School, Faculty of Medicine and Health, University of Sydney, Royal North Shore Hospital, St Leonards, NSW, Australia
- Ji Bian,
| | - Lan Gong
- Microbiome Research Centre, St George and Sutherland Clinical School, University of New South Wales, Sydney, NSW, Australia
- Lan Gong,
| | - Min Wang
- College of Food Science and Engineering, Northwest A&F University, Yangling, China
- Min Wang,
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6
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Ye X, Zhang T, Han H. PPARα: A potential therapeutic target of cholestasis. Front Pharmacol 2022; 13:916866. [PMID: 35924060 PMCID: PMC9342652 DOI: 10.3389/fphar.2022.916866] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Accepted: 06/29/2022] [Indexed: 12/12/2022] Open
Abstract
The accumulation of bile acids in the liver leads to the development of cholestasis and hepatocyte injury. Nuclear receptors control the synthesis and transport of bile acids in the liver. Among them, the farnesoid X receptor (FXR) is the most common receptor studied in treating cholestasis. The activation of this receptor can reduce the amount of bile acid synthesis and decrease the bile acid content in the liver, alleviating cholestasis. Ursodeoxycholic acid (UDCA) and obeticholic acid (OCA) have a FXR excitatory effect, but the unresponsiveness of some patients and the side effect of pruritus seriously affect the results of UDCA or OCA treatment. The activator of peroxisome proliferator-activated receptor alpha (PPARα) has emerged as a new target for controlling the synthesis and transport of bile acids during cholestasis. Moreover, the anti-inflammatory effect of PPARα can effectively reduce cholestatic liver injury, thereby improving patients’ physiological status. Here, we will focus on the function of PPARα and its involvement in the regulation of bile acid transport and metabolism. In addition, the anti-inflammatory effects of PPARα will be discussed in some detail. Finally, we will discuss the application of PPARα agonists for cholestatic liver disorders.
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Affiliation(s)
- Xiaoyin Ye
- School of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Tong Zhang
- School of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China
- *Correspondence: Tong Zhang, ; Han Han,
| | - Han Han
- Experiment Center for Teaching and Learning, Shanghai University of Traditional Chinese Medicine, Shanghai, China
- *Correspondence: Tong Zhang, ; Han Han,
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7
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Xu S, Qiao X, Peng P, Zhu Z, Li Y, Yu M, Chen L, Cai Y, Xu J, Shi X, Proud CG, Xie J, Shen K. Da-Chai-Hu-Tang Protects From Acute Intrahepatic Cholestasis by Inhibiting Hepatic Inflammation and Bile Accumulation via Activation of PPARα. Front Pharmacol 2022; 13:847483. [PMID: 35370715 PMCID: PMC8965327 DOI: 10.3389/fphar.2022.847483] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2022] [Accepted: 02/15/2022] [Indexed: 12/12/2022] Open
Abstract
Cholestasis is caused by intrahepatic retention of excessive toxic bile acids and ultimately results in hepatic failure. Da-Chai-Hu-Tang (DCHT) has been used in China to treat liver and gallbladder diseases for over 1800 years. Here, we demonstrated that DCHT treatment prevented acute intrahepatic cholestasis with liver injury in response to α-naphthylisothiocyanate (ANIT) not to bile duct ligation (BDL) induced-extrahepatic cholestasis. ANIT (80 mg/kg) increased serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), direct bilirubin (DBiL), total bilirubin (TBiL), and total bile acids (TBA) which was attenuated by DCHT treatment in a dose-dependent manner. DCHT treatment at high dose of 1.875 g/kg restored bile acid homeostasis, as evidenced by the recovery of the transcription of genes implicated in bile acid biosynthesis, uptake and efflux. DCHT treatment (1.875 g/kg) reversed ANIT-evoked disordered glutathione homeostasis (as determined by GSH/GSSG ratio) and increased in the mRNA levels for Il6, Il1b and Tnfa associated with liver inflammation. Using network pharmacology-based approaches, we identified 22 putative targets involved in DCHT treatment for intrahepatic cholestasis not extrahepatic cholestasis. In addition, as evidenced by dual-luciferase reporter assays, compounds from DCHT with high affinity of PPARα increased luciferase levels from a PPARα-driven reporter. PPARα agonist fenofibrate was able to mimic the cytoprotective effect of DCHT on intrahepatic cholestasis, which was abolished by the PPARα antagonist GW6471. KEGG enrichment and western blot analyses showed that signaling axes of JNK/IL-6/NF-κB/STAT3 related to PPARα might be the principal pathway DCHT affects intrahepatic cholestasis. Taken together, the present study provides compelling evidence that DCHT is a promising formula against acute intrahepatic cholestasis with hepatotoxicity which works via PPARα activation.
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Affiliation(s)
- Shihao Xu
- School of Basic Medical Sciences, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Xi Qiao
- School of Basic Medical Sciences, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Peike Peng
- School of Basic Medical Sciences, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Ziyi Zhu
- School of Basic Medical Sciences, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Yaoting Li
- School of Basic Medical Sciences, Shanghai University of Traditional Chinese Medicine, Shanghai, China.,School of Pharmacy, Fudan University, Shanghai, China
| | - Mengyuan Yu
- School of Basic Medical Sciences, Shanghai University of Traditional Chinese Medicine, Shanghai, China.,School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Long Chen
- Experimental Center for Science and Technology, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Yin Cai
- Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
| | - Jin Xu
- School of Basic Medical Sciences, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Xinwei Shi
- School of Basic Medical Sciences, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Christopher G Proud
- Lifelong Health Theme, South Australian Health and Medical Research Institute, Adelaide, SA, Australia.,Molecular and Biomedical Sciences, School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia
| | - Jianling Xie
- Lifelong Health Theme, South Australian Health and Medical Research Institute, Adelaide, SA, Australia.,Flinders Health and Medical Research Institute, Flinders University, Adelaide, SA, Australia
| | - Kaikai Shen
- School of Basic Medical Sciences, Shanghai University of Traditional Chinese Medicine, Shanghai, China
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8
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Zhang J, Yu H, Zhong H, Wang Q, Tang J, Shen F, Cai H, Liu T, Feng F, Zhao M. Dietary emulsifier glycerol monodecanoate affects gut microbiota contributing to regulating lipid metabolism, insulin sensitivity and inflammation. Food Funct 2022; 13:8804-8817. [DOI: 10.1039/d2fo01689c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Glycerol monodecanoate (GMD) is a medium-chain monoacylglycerol that possesses emulsifying and antibacterial properties. Common emulsifiers carboxymethylcellulose and polysorbate-80 have been reported to cause intestinal microbiota dysbiosis and metabolic disturbances. While...
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9
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Wang M, Xu G, Tang Y, Su S, Wang Y, Zhu Z. Investigation of the Molecular Mechanisms of Antioxidant Damage and Immune Response Downregulation in Liver of Coilia nasus Under Starvation Stress. Front Endocrinol (Lausanne) 2021; 12:622315. [PMID: 33732214 PMCID: PMC7959721 DOI: 10.3389/fendo.2021.622315] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 01/08/2021] [Indexed: 01/11/2023] Open
Abstract
Commercial fishing of estuarine tapertail anchovy (Coilia nasus), an important anadromous fish species in the Yangtze River of China, has been prohibited due to the serious damage overfishing has caused to the wild population. Research regarding the energy metabolism is important for migratory fish to ensure the continuation of their existence. In this study, we performed, for the first time, a comparative transcriptome analysis of the liver of C. nasus subjected to long-term starvation stress. The results indicated that the damaging effects involved downregulation of the antioxidant capacity and immune response. The positive response to starvation involved upregulation of the anti-allergy and anticancer capacity, which supports the function of starvation in cancer inhibition, as has also been determined for human beings. This study revealed regulatory pathways, differentially expressed genes (DEGs), and mechanisms leading to damage of the liver in C. nasus affected by starvation. This research contributes information for the further study of the energy metabolism mechanism of C. nasus and provides a theoretical reference for starvation metabolism research of other fish species and even human beings.
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Affiliation(s)
- Meiyao Wang
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi, China
- Wuxi Fisheries College, Nanjing Agricultural University, Wuxi, China
- Aquatic Animal Genome Center of Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi, China
| | - Gangchun Xu
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi, China
- Wuxi Fisheries College, Nanjing Agricultural University, Wuxi, China
- *Correspondence: Gangchun Xu, ; Yongkai Tang,
| | - Yongkai Tang
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi, China
- Wuxi Fisheries College, Nanjing Agricultural University, Wuxi, China
- Aquatic Animal Genome Center of Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi, China
- *Correspondence: Gangchun Xu, ; Yongkai Tang,
| | - Shengyan Su
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi, China
- Wuxi Fisheries College, Nanjing Agricultural University, Wuxi, China
- Aquatic Animal Genome Center of Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi, China
| | - Yinping Wang
- Scientific Observing and Experimental Station of Fishery Resources and Environment in the Lower Reaches of the Changjiang River, Ministry of Agriculture and Rural Affairs, Wuxi, China
| | - Zhixiang Zhu
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi, China
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10
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Mice depleted for Exchange Proteins Directly Activated by cAMP (Epac) exhibit irregular liver regeneration in response to partial hepatectomy. Sci Rep 2019; 9:13789. [PMID: 31551444 PMCID: PMC6760117 DOI: 10.1038/s41598-019-50219-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 09/06/2019] [Indexed: 02/07/2023] Open
Abstract
The exchange proteins directly activated by cAMP 1 and 2 (Epac1 and Epac2) are expressed in a cell specific manner in the liver, but their biological functions in this tissue are poorly understood. The current study was undertaken to begin to determine the potential roles of Epac1 and Epac2 in liver physiology and disease. Male C57BL/6J mice in which expression of Epac1 and/or Epac2 are deleted, were subjected to partial hepatectomy and the regenerating liver was analyzed with regard to lipid accumulation, cell replication and protein expression. In response to partial hepatectomy, deletion of Epac1 and/or Epac2 led to increased hepatocyte proliferation 36 h post surgery, and the transient steatosis observed in wild type mice was virtually absent in mice lacking both Epac1 and Epac2. The expression of the protein cytochrome P4504a14, which is implicated in hepatic steatosis and fibrosis, was substantially reduced upon deletion of Epac1/2, while a number of factors involved in lipid metabolism were significantly decreased. Moreover, the number of Küpffer cells was affected, and Epac2 expression was increased in the liver of wild type mice in response to partial hepatectomy, further supporting a role for these proteins in liver function. This study establishes hepatic phenotypic abnormalities in mice deleted for Epac1/2 for the first time, and introduces Epac1/2 as regulators of hepatocyte proliferation and lipid accumulation in the regenerative process.
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11
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Xie C, Takahashi S, Brocker CN, He S, Chen L, Xie G, Jang K, Gao X, Krausz KW, Qu A, Levi M, Gonzalez FJ. Hepatocyte peroxisome proliferator-activated receptor α regulates bile acid synthesis and transport. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1864:1396-1411. [PMID: 31195146 DOI: 10.1016/j.bbalip.2019.05.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 02/05/2019] [Accepted: 05/28/2019] [Indexed: 12/12/2022]
Abstract
Peroxisome proliferator-activated receptor alpha (PPARα) controls lipid homeostasis through regulation of lipid transport and catabolism. PPARα activators are clinically used for hyperlipidemia treatment. The role of PPARα in bile acid (BA) homeostasis is beginning to emerge. Herein, Ppara-null and hepatocyte-specific Ppara-null (Ppara∆Hep) as well as the respective wild-type mice were treated with the potent PPARα agonist Wy-14,643 (Wy) and global metabolomics performed to clarify the role of hepatocyte PPARα in the regulation of BA homeostasis. Levels of all serum BAs were markedly elevated in Wy-treated wild-type mice but not in Ppara-null and Ppara∆Hep mice. Gene expression analysis showed that PPARα activation (1) down-regulated the expression of sodium-taurocholate acid transporting polypeptide and organic ion transporting polypeptide 1 and 4, responsible for the uptake of BAs into the liver; (2) decreased the expression of bile salt export pump transporting BA from hepatocytes into the bile canaliculus; (3) upregulated the expression of multidrug resistance-associated protein 3 and 4 transporting BA from hepatocytes into the portal vein. Moreover, there was a notable increase in the compositions of serum, hepatic and biliary cholic acid and taurocholic acid following Wy treatment, which correlated with the upregulated expression of the Cyp8b1 gene encoding sterol 12α-hydroxylase. The effects of Wy were identical between the Ppara∆Hep and Ppara-null mice. Hepatocyte PPARα controlled BA synthesis and transport not only via direct transcriptional regulation but also via crosstalk with hepatic farnesoid X receptor signaling. These findings underscore a key role for hepatocyte PPARα in the control of BA homeostasis.
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Affiliation(s)
- Cen Xie
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 2089, United States of America; State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, PR China.
| | - Shogo Takahashi
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 2089, United States of America; Department of Biochemistry and Molecular and Cellular Biology, Georgetown University, Washington, DC, United States of America.
| | - Chad N Brocker
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 2089, United States of America.
| | - Shijun He
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, PR China.
| | - Li Chen
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
| | - Guomin Xie
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Key Laboratory of Remodeling-Related Cardiovascular Diseases, Ministry of Education, Beijing 100069, PR China.
| | - Katrina Jang
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 2089, United States of America.
| | - Xiaoxia Gao
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 2089, United States of America.
| | - Kristopher W Krausz
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 2089, United States of America.
| | - Aijuan Qu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Key Laboratory of Remodeling-Related Cardiovascular Diseases, Ministry of Education, Beijing 100069, PR China.
| | - Moshe Levi
- Department of Biochemistry and Molecular and Cellular Biology, Georgetown University, Washington, DC, United States of America.
| | - Frank J Gonzalez
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 2089, United States of America.
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12
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Ge MX, Shao RG, He HW. Advances in understanding the regulatory mechanism of cholesterol 7α-hydroxylase. Biochem Pharmacol 2019; 164:152-164. [DOI: 10.1016/j.bcp.2019.04.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 04/08/2019] [Indexed: 02/07/2023]
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13
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Cheema SK, Tappia PS, Dhalla NS. Modification of gene expression in rat cardiomyocytes by linoleic and docosahexaenoic acids 1. Can J Physiol Pharmacol 2018; 97:320-327. [PMID: 30388381 DOI: 10.1139/cjpp-2018-0398] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Regulation of cardiac fatty acid metabolism is central to the development of cardiac hypertrophy and heart failure. We investigated the effects of select fatty acids on the expression of genes involved in immediate early as well as inflammatory and hypertrophic responses in adult rat cardiomyocytes. Cardiac remodeling begins with upregulation of immediate early genes for c-fos and c-jun, followed by upregulation of inflammatory genes for nuclear factor kappa B (NF-κB) and nuclear factor of activated T-cells (NFAT). At later stages, genes involved in hypertrophic responses, such as atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), are upregulated. Adult rat cardiomyocytes were treated with palmitic acid, a saturated fatty acid; oleic acid, a monounsaturated fatty acid; linoleic acid, a polyunsaturated fatty acid belonging to the n-6 class; and docosahexaenoic acid, a polyunsaturated fatty acid belonging to the n-3 class. Linoleic acid produced a greater increase in the mRNA expression of c-fos, c-jun, NF-κB, NFAT3, ANP, and BNP relative to palmitic acid and oleic acid. In contrast, docosahexaenoic acid caused a decrease in the expression of genes involved in cardiac hypertrophy. Our findings suggest that linoleic acid may be a potent inducer of genes involved in cardiac hypertrophy, whereas docosahexaenoic acid may be protective against the cardiomyocyte hypertrophic response.
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Affiliation(s)
- Sukhinder K Cheema
- a Department of Biochemistry, Memorial University of Newfoundland, St. John's, NL A1B 3X9, Canada
| | - Paramjit S Tappia
- b Asper Clinical Research Institute, St. Boniface Hospital, Winnipeg, MB R2H 2A6, Canada
| | - Naranjan S Dhalla
- c Institute of Cardiovascular Sciences, University of Manitoba, St. Boniface Hospital, Albrechtsen Research Centre, Winnipeg, MB R2H 2A6, Canada
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14
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Bougarne N, Weyers B, Desmet SJ, Deckers J, Ray DW, Staels B, De Bosscher K. Molecular Actions of PPARα in Lipid Metabolism and Inflammation. Endocr Rev 2018; 39:760-802. [PMID: 30020428 DOI: 10.1210/er.2018-00064] [Citation(s) in RCA: 378] [Impact Index Per Article: 63.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2018] [Accepted: 07/10/2018] [Indexed: 12/13/2022]
Abstract
Peroxisome proliferator-activated receptor α (PPARα) is a nuclear receptor of clinical interest as a drug target in various metabolic disorders. PPARα also exhibits marked anti-inflammatory capacities. The first-generation PPARα agonists, the fibrates, have however been hampered by drug-drug interaction issues, statin drop-in, and ill-designed cardiovascular intervention trials. Notwithstanding, understanding the molecular mechanisms by which PPARα works will enable control of its activities as a drug target for metabolic diseases with an underlying inflammatory component. Given its role in reshaping the immune system, the full potential of this nuclear receptor subtype as a versatile drug target with high plasticity becomes increasingly clear, and a novel generation of agonists may pave the way for novel fields of applications.
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Affiliation(s)
- Nadia Bougarne
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
- Receptor Research Laboratories, Nuclear Receptor Laboratory, VIB Center for Medical Biotechnology, Ghent, Belgium
| | - Basiel Weyers
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
- Receptor Research Laboratories, Nuclear Receptor Laboratory, VIB Center for Medical Biotechnology, Ghent, Belgium
| | - Sofie J Desmet
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
- Receptor Research Laboratories, Nuclear Receptor Laboratory, VIB Center for Medical Biotechnology, Ghent, Belgium
| | - Julie Deckers
- Department of Internal Medicine, Ghent University, Ghent, Belgium
- Laboratory of Immunoregulation, VIB Center for Inflammation Research, Ghent (Zwijnaarde), Belgium
| | - David W Ray
- Division of Metabolism and Endocrinology, Faculty of Biology, Medicine, and Health, University of Manchester, Manchester, United Kingdom
| | - Bart Staels
- Université de Lille, U1011-European Genomic Institute for Diabetes, Lille, France
- INSERM, U1011, Lille, France
- Centre Hospitalier Universitaire de Lille, Lille, France
- Institut Pasteur de Lille, Lille, France
| | - Karolien De Bosscher
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
- Receptor Research Laboratories, Nuclear Receptor Laboratory, VIB Center for Medical Biotechnology, Ghent, Belgium
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15
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Expression of cytochrome P450 epoxygenases and soluble epoxide hydrolase is regulated by hypolipidemic drugs in dose-dependent manner. Toxicol Appl Pharmacol 2018; 355:156-163. [DOI: 10.1016/j.taap.2018.06.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 06/25/2018] [Accepted: 06/26/2018] [Indexed: 01/30/2023]
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16
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Zhang Y, Lickteig AJ, Csanaky IL, Klaassen CD. Editor's Highlight: Clofibrate Decreases Bile Acids in Livers of Male Mice by Increasing Biliary Bile Acid Excretion in a PPARα-Dependent Manner. Toxicol Sci 2018; 160:351-360. [PMID: 28973556 DOI: 10.1093/toxsci/kfx191] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Fibrates and their receptor, namely peroxisome proliferator-activated receptor α (PPARα), have been reported to regulate bile acid (BA) synthesis and transport. However, the effect of fibrate treatment and PPARα activation on BA homeostasis remains controversial. In this study, both wild-type (WT) and PPARα-null male mice were treated with clofibrate (CLOF) for 4 days to evaluate the effects of short-term PPARα activation on BA homeostasis. Although a decrease in total BAs (ΣBAs) was observed in livers of CLOF-treated WT mice, it was not observed in PPARα-null mice. CLOF-mediated decrease in ΣBAs in the liver was not likely due to the reduction in BA synthesis or BA uptake, as evidenced by an increase in the BA synthetic enzyme (Cyp7a1) and 2 BA uptake transporters (Na (+)-taurocholate cotransporting polypeptide [Ntcp] and organic anion transporting polypeptide [Oatp]1b2). Instead, the decrease in liver BAs by CLOF is largely a result of increased biliary excretion of BAs, which was associated with a significant induction of the canalicular efflux transporter (bile salt export pump [Bsep]) in the liver. The PPARα-mediated increase in Cyp7a1 in CLOF-treated WT mice was not due to farnesoid X receptor (Fxr)-small heterodimer partner (Shp) signaling in the liver, but due to suppression of Fxr- fibroblast growth factor15 signaling in the ileum. Additionally, CLOF also suppressed intestinal BA transporters (apical sodium-dependent bile acid transporter and organic solute transporterβ) and cholesterol efflux transporters (Abcg5 and Abcg8) in a PPARα-dependent manner. In summary, this study provides the first comprehensive analysis on the effect of a short-term CLOF treatment on BA homeostasis, and revealed an essential role of PPARα in regulating BA synthesis, transport and signaling.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 11/metabolism
- ATP Binding Cassette Transporter, Subfamily G, Member 5/metabolism
- ATP Binding Cassette Transporter, Subfamily G, Member 8/metabolism
- Animals
- Bile Acids and Salts/metabolism
- Clofibrate/pharmacology
- Fibroblast Growth Factors/metabolism
- Gastrointestinal Agents/pharmacology
- Genotype
- Homeostasis
- Ileum/drug effects
- Ileum/metabolism
- Lipoproteins/metabolism
- Liver/drug effects
- Liver/metabolism
- Male
- Membrane Transport Proteins/metabolism
- Mice, Inbred C57BL
- Mice, Knockout
- Organic Anion Transporters, Sodium-Dependent/metabolism
- PPAR alpha/agonists
- PPAR alpha/genetics
- PPAR alpha/metabolism
- Phenotype
- Receptors, Cytoplasmic and Nuclear/antagonists & inhibitors
- Receptors, Cytoplasmic and Nuclear/metabolism
- Signal Transduction/drug effects
- Steroid 17-alpha-Hydroxylase/metabolism
- Symporters/metabolism
- Time Factors
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Affiliation(s)
- Youcai Zhang
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
| | - Andrew J Lickteig
- Department of Internal Medicine, University of Kansas Medical Center, Kansas City, Kansas 66160
| | - Iván L Csanaky
- Division of Clinical Pharmacology, Toxicology and Therapeutic Innovation, Division of Gastroenterology, Children's Mercy Hospital & Clinics, Kansas City, Missouri 64108
- Department of Pediatrics, University of Kansas Medical Center, Kansas City, Kansas 66160
| | - Curtis D Klaassen
- Department of Internal Medicine, University of Kansas Medical Center, Kansas City, Kansas 66160
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17
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Zhao Q, Yang R, Wang J, Hu DD, Li F. PPARα activation protects against cholestatic liver injury. Sci Rep 2017; 7:9967. [PMID: 28855630 PMCID: PMC5577315 DOI: 10.1038/s41598-017-10524-6] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 08/10/2017] [Indexed: 12/13/2022] Open
Abstract
Intrahepatic cholestasis induced by drug toxicity, bile salt export pump (BSEP) deficiency, or pregnancy frequently causes cholestatic liver damage, which ultimately may lead to liver fibrosis and cirrhosis. Here, the preventive and therapeutic effects of peroxisome proliferator-activated receptor α (PPARα) signaling activated by fenofibrate was evaluated on cholestatic liver damage. Metabolomic analysis revealed that alpha-naphthyl isothiocyanate (ANIT)-induced intrahepatic cholestasis resulted in the accumulation of serum long-chain acylcarnitines and triglyceride, and the reduced expression of four fatty acid β-oxidation (β-FAO) relevant genes (Cpt1b, Cpt2, Mcad and Hadha), indicating the disruption of β-FAO. The increase of acylcarnitines in hepatic cell resulted in the enhanced expression of anti-oxidative genes glutathione S-transferases (Gsta2 and Gstm3) directly. As direct PPARα-regulated genes, Cpt1b, Cpt2, and Mcad were up-regulated after pretreatment with PPARα agonist, fenofibrate, indicating the improvement of β-FAO. In the end, the disrupted bile acid metabolism in the enterohepatic circulation and the enhanced oxidative stress and inflammation cytokines induced by ANIT exposure were significantly recovered with the improvement of β-FAO using fenofibrate treatment. These findings provide the rationale for the use of PPARα agonists as therapeutic alternatives for cholestatic liver damage.
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Affiliation(s)
- Qi Zhao
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Rui Yang
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jing Wang
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China
| | - Dan-Dan Hu
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China.,School of Pharmaceutical Science and Yunnan Key Laboratory of Pharmacology of Natural Products, Kunming Medical University, Kunming, 650500, China
| | - Fei Li
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China.
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18
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Cizkova K, Steigerova J, Gursky J, Ehrmann J. Stimulating effect of normal-dosing of fibrates on cell proliferation: word of warning. Lipids Health Dis 2016; 15:164. [PMID: 27658584 PMCID: PMC5034623 DOI: 10.1186/s12944-016-0335-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 09/14/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Fibrates are widely used hypolipidemic drugs, which serve as ligand of peroxisome proliferator-activated receptor α (PPARα). Recently, they have also been considered as potential anticancer agents. We studied effect of fibrates treatment on cell proliferation, expression of CYP2J2 and concomitant changes in expression of cell cycle regulatory proteins in three different human cell lines: HEK293, HepG2, and HT-29. METHODS We used WST-1 viability test, western blot and immunocytochemistry for detection of proteins of interests and analysis of cell cycle. RESULTS Our results showed that at lower concentrations of all tested fibrates, viability of all tested cell lines is increased, whereas at higher concentrations, repression is apparent. Unfortunately, the viability of tested cells is predominantly increased in a range of concentration which is reached in patient plasma. This phenomenon is accompanyed by elevation of CYP2J2, increased number of cyclin E-positive cells and decreased number of Cdc25A-positive cells in all tested cell lines, and elevated cyclin A expression in HepG2 and HT-29. These changes are concentration-dependent. We suppose that increased level of CYP2J2 could explain enhanced cell proliferation in lower concentration of fibrates. CONCLUSION Based on our results, we suggested there is no anti-cancer effect of fibrates in tested carcinoma cell lines.
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Affiliation(s)
- Katerina Cizkova
- Department of Histology and Embryology, Faculty of Medicine and Dentistry, Palacky University Olomouc, Hnevotinska 3, 775 15, Olomouc, Czech Republic.
| | - Jana Steigerova
- Department of Clinical and Molecular Pathology & Laboratory of Molecular Pathology, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 3, 775 15, Olomouc, Czech Republic
| | - Jan Gursky
- Institute of Molecular and Translation Medicine, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 5, 775 15, Olomouc, Czech Republic
| | - Jiri Ehrmann
- Department of Histology and Embryology, Faculty of Medicine and Dentistry, Palacky University Olomouc, Hnevotinska 3, 775 15, Olomouc, Czech Republic.,Department of Clinical and Molecular Pathology & Laboratory of Molecular Pathology, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 3, 775 15, Olomouc, Czech Republic
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PPARα-UGT axis activation represses intestinal FXR-FGF15 feedback signalling and exacerbates experimental colitis. Nat Commun 2014; 5:4573. [PMID: 25183423 PMCID: PMC4164778 DOI: 10.1038/ncomms5573] [Citation(s) in RCA: 115] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 07/02/2014] [Indexed: 02/07/2023] Open
Abstract
Bile acids play a pivotal role in the pathological development of inflammatory bowel disease (IBD). However, the mechanism of bile acid dysregulation in IBD remains unanswered. Here we show that intestinal peroxisome proliferator-activated receptor α (PPARα)-UDP-glucuronosyltransferases (UGTs) signalling is an important determinant of bile acid homeostasis. Dextran sulphate sodium (DSS)-induced colitis leads to accumulation of bile acids in inflamed colon tissues via activation of the intestinal peroxisome PPARα-UGTs pathway. UGTs accelerate the metabolic elimination of bile acids, and thereby decrease their intracellular levels in the small intestine. Reduced intracellular bile acids results in repressed farnesoid X receptor (FXR)-FGF15 signalling, leading to upregulation of hepatic CYP7A1, thus promoting the de novo bile acid synthesis. Both knockout of PPARα and treatment with recombinant FGF19 markedly attenuate DSS-induced colitis. Thus, we propose that intestinal PPARα-UGTs and downstream FXR-FGF15 signalling play vital roles in control of bile acid homeostasis and the pathological development of colitis. Bile acids have been linked to the development of inflammatory bowel diseases, such as colitis. Here the authors show that bile acid levels in mice are controlled by a circular feedback system involving the nuclear receptors PPARα and FXR, and that this system is dysregulated in colitis.
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20
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The Proatherogenic Effect of Chronic Nitric Oxide Synthesis Inhibition in ApoE-Null Mice Is Dependent on the Presence of PPAR α. PPAR Res 2014; 2014:124583. [PMID: 24587793 PMCID: PMC3920724 DOI: 10.1155/2014/124583] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2013] [Revised: 10/14/2013] [Accepted: 10/18/2013] [Indexed: 12/17/2022] Open
Abstract
Inhibition of endothelial nitric oxide synthase (eNOS) accelerates atherosclerosis in ApoE-null mice by impairing the balance between angiotensin II (AII) and NO. Our previous data suggested a role for PPARα in the deleterious effect of the renin-angiotensin system (RAS). We tested the hypothesis that ApoE-null mice lacking PPARα (DKO mice) would be resistant to the proatherogenic effect of NOS inhibition. DKO mice fed a Western diet were immune to the 23% worsening in aortic sinus plaque area seen in the ApoE-null animals under 12 weeks of NOS inhibition with a subpressor dose of L-NAME, P = 0.002. This was accompanied by a doubling of reactive oxygen species (ROS-) generating aortic NADPH oxidase activity (a target of AII, which paralleled Nox1 expression) and by a 10-fold excess of the proatherogenic iNOS, P < 0.01. L-NAME also caused a doubling of aortic renin and angiotensinogen mRNA level in the ApoE-null mice but not in the DKO, and it upregulated eNOS in the DKO mice only. These data suggest that, in the ApoE-null mouse, PPARα contributes to the proatherogenic effect of unopposed RAS/AII action induced by L-NAME, an effect which is associated with Nox1 and iNOS induction, and is independent of blood pressure and serum lipids.
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21
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Gemfibrozil disrupts lysophosphatidylcholine and bile acid homeostasis via PPARα and its relevance to hepatotoxicity. Arch Toxicol 2014; 88:983-96. [PMID: 24385052 DOI: 10.1007/s00204-013-1188-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2013] [Accepted: 12/18/2013] [Indexed: 01/14/2023]
Abstract
Gemfibrozil, a ligand of peroxisome proliferator-activated receptor α (PPARα), is one of the most widely prescribed anti-dyslipidemia fibrate drugs. Among the adverse reactions observed with gemfibrozil are alterations in liver function, cholestatic jaundice, and cholelithiasis. However, the mechanisms underlying these toxicities are poorly understood. In this study, wild-type and Ppara-null mice were dosed with a gemfibrozil-containing diet for 14 days. Ultra-performance chromatography electrospray ionization quadrupole time-of-flight mass spectrometry-based metabolomics and traditional approaches were used to assess the mechanism of gemfibrozil-induced hepatotoxicity. Unsupervised multivariate data analysis revealed four lysophosphatidylcholine components in wild-type mice that varied more dramatically than those in Ppara-null mice. Targeted metabolomics revealed taurocholic acid and tauro-α-muricholic acid/tauro-β-muricholic acid were significantly increased in wild-type mice, but not in Ppara-null mice. In addition to the above perturbations in metabolite homeostasis, phenotypic alterations in the liver were identified. Hepatic genes involved in metabolism and transportation of lysophosphatidylcholine and bile acid compounds were differentially regulated between wild-type and Ppara-null mice, in agreement with the observed downstream metabolic alterations. These data suggest that PPARα mediates gemfibrozil-induced hepatotoxicity in part by disrupting phospholipid and bile acid homeostasis.
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22
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Transport and biological activities of bile acids. Int J Biochem Cell Biol 2013; 45:1389-98. [PMID: 23603607 DOI: 10.1016/j.biocel.2013.04.012] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2013] [Revised: 03/30/2013] [Accepted: 04/09/2013] [Indexed: 12/29/2022]
Abstract
Bile acids have emerged as important biological molecules that support the solubilization of various lipids and lipid-soluble compounds in the gut, and the regulation of gene expression and cellular function. Bile acids are synthesized from cholesterol in the liver and eventually released into the small intestine. The majority of bile acids are recovered in the distal end of the small intestine and then returned to the liver for reuse. The components of the mechanism responsible for the recycling of bile acids within the enterohepatic circulation have been identified whereas the mechanism for intracellular transport is less understood. Recently, the ileal lipid binding protein (ILBP; human gene symbol FABP6) was shown to be needed for the efficient transport of bile acids from the apical side to the basolateral side of enterocytes in the distal intestine. This review presents an overview of the transport of bile acids between the liver and the gut as well as within hepatocytes and enterocytes. A variety of pathologies is associated with the malfunction of the bile acid transport system.
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23
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Li F, Patterson AD, Krausz KW, Tanaka N, Gonzalez FJ. Metabolomics reveals an essential role for peroxisome proliferator-activated receptor α in bile acid homeostasis. J Lipid Res 2012; 53:1625-35. [PMID: 22665165 PMCID: PMC3540854 DOI: 10.1194/jlr.m027433] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Revised: 06/04/2012] [Indexed: 12/15/2022] Open
Abstract
Peroxisome proliferator-activated receptor α (PPARα) is a nuclear receptor that regulates fatty acid transport and metabolism. Previous studies revealed that PPARα can affect bile acid metabolism; however, the mechanism by which PPARα regulates bile acid homeostasis is not understood. In this study, an ultraperformance liquid chromatography coupled with electrospray ionization qua dru pole time-of-flight mass spectrometry (UPLC-ESI-QTOFMS)-based metabolomics approach was used to profile metabolites in urine, serum, and bile of wild-type and Ppara-null mice following cholic acid (CA) dietary challenge. Metabolomic analysis showed that the levels of several serum bile acids, such as CA (25-fold) and taurocholic acid (16-fold), were significantly increased in CA-treated Ppara-null mice compared with CA-treated wild-type mice. Phospholipid homeostasis, as revealed by decreased serum lysophos phati dylcholine (LPC) 16:0 (1.6-fold) and LPC 18:0 (1.6-fold), and corticosterone metabolism noted by increased urinary excretion of 11β-hydroxy-3,20-dioxopregn-4-en-21-oic acid (20-fold) and 11β,20α-dihydroxy-3-oxo-pregn-4-en-21-oic acid (3.6-fold), were disrupted in CA-treated Ppara-null mice. The hepatic levels of mRNA encoding transporters Abcb11, Abcb4, Abca1, Abcg5, and Abcg8 were diminished in Ppara-null mice, leading to the accumulation of bile acids in the liver during the CA challenge. These observations revealed that PPARα is an essential regulator of bile acid biosynthesis, transport, and secretion.
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Affiliation(s)
- Fei Li
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD; and
| | - Andrew D. Patterson
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD; and
- Department of Veterinary and Biomedical Sciences and Pennsylvania State University, University Park, PA
- Center for Molecular Toxicology and Carcinogenesis, Pennsylvania State University, University Park, PA
| | - Kristopher W. Krausz
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD; and
| | - Naoki Tanaka
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD; and
| | - Frank J. Gonzalez
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD; and
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Role of nuclear receptors for bile acid metabolism, bile secretion, cholestasis, and gallstone disease. Biochim Biophys Acta Mol Basis Dis 2011; 1812:867-78. [DOI: 10.1016/j.bbadis.2010.12.021] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Revised: 12/21/2010] [Accepted: 12/22/2010] [Indexed: 12/12/2022]
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Rakhshandehroo M, Knoch B, Müller M, Kersten S. Peroxisome proliferator-activated receptor alpha target genes. PPAR Res 2010; 2010:612089. [PMID: 20936127 PMCID: PMC2948931 DOI: 10.1155/2010/612089] [Citation(s) in RCA: 532] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Accepted: 08/09/2010] [Indexed: 12/11/2022] Open
Abstract
The peroxisome proliferator-activated receptor alpha (PPARα) is a ligand-activated transcription factor involved in the regulation of a variety of processes, ranging from inflammation and immunity to nutrient metabolism and energy homeostasis. PPARα serves as a molecular target for hypolipidemic fibrates drugs which bind the receptor with high affinity. Furthermore, PPARα binds and is activated by numerous fatty acids and fatty acid-derived compounds. PPARα governs biological processes by altering the expression of a large number of target genes. Accordingly, the specific role of PPARα is directly related to the biological function of its target genes. Here, we present an overview of the involvement of PPARα in lipid metabolism and other pathways through a detailed analysis of the different known or putative PPARα target genes. The emphasis is on gene regulation by PPARα in liver although many of the results likely apply to other organs and tissues as well.
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Affiliation(s)
- Maryam Rakhshandehroo
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Bomenweg 2, 6703 HD Wageningen, The Netherlands
| | - Bianca Knoch
- Food, Metabolism & Microbiology, Food & Textiles Group, AgResearch, Palmerston North 4442, New Zealand
- Institute of Food, Nutrition & Human Health, Massey University, Tennent Drive, Palmerston North 4442, New Zealand
| | - Michael Müller
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Bomenweg 2, 6703 HD Wageningen, The Netherlands
| | - Sander Kersten
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Bomenweg 2, 6703 HD Wageningen, The Netherlands
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Abstract
PPARα is one of three members of the soluble nuclear receptor family called peroxisome proliferator-activated receptor (PPAR). It is a sensor for changes in levels of fatty acids and their derivatives that responds to ligand binding with PPAR target gene transcription, inasmuch as it can influence physiological homeostasis, including lipid and carbohydrate metabolism in various tissues. In this paper we summarize the involvement of PPARα in the metabolically active tissues liver and skeletal muscle and provide an overview of the risks and benefits of ligand activation of PPARα, with particular consideration to interspecies differences.
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Liu YY, Brent GA. Thyroid hormone crosstalk with nuclear receptor signaling in metabolic regulation. Trends Endocrinol Metab 2010; 21:166-73. [PMID: 20015660 PMCID: PMC2831161 DOI: 10.1016/j.tem.2009.11.004] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Revised: 11/14/2009] [Accepted: 11/17/2009] [Indexed: 12/31/2022]
Abstract
Thyroid hormone influences diverse metabolic pathways important in lipid and glucose metabolism, lipolysis and regulation of body weight. Recently, it has been recognized that thyroid hormone receptor interacts with transcription factors that predominantly respond to nutrient signals including the peroxisome proliferator-activated receptors, liver X receptor and others. Crosstalk between thyroid hormone signaling and these nutrient responsive factors occurs through a variety of mechanisms: competition for retinoid X receptor heterodimer partners, DNA binding sites and transcriptional cofactors. This review focuses on the mechanisms of interaction of thyroid hormone signaling with other metabolic pathways and the importance of understanding these interactions to develop therapeutic agents for treatment of metabolic disorders, such as dyslipidemias, obesity and diabetes.
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Affiliation(s)
- Yan-Yun Liu
- Molecular Endocrinology Laboratory, VA Greater Los Angeles Healthcare System, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA 90073, USA
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Pirinen E, Gylling H, Itkonen P, Yaluri N, Heikkinen S, Pietilä M, Kuulasmaa T, Tusa M, Cerrada-Gimenez M, Pihlajamäki J, Alhonen L, Jänne J, Miettinen TA, Laakso M. Activated polyamine catabolism leads to low cholesterol levels by enhancing bile acid synthesis. Amino Acids 2009; 38:549-60. [PMID: 19956992 DOI: 10.1007/s00726-009-0416-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Accepted: 09/21/2009] [Indexed: 11/29/2022]
Abstract
Transgenic mice with activated polyamine catabolism due to overexpression of spermidine/spermine N(1)-acetyltransferase (SSAT) have significantly reduced plasma total cholesterol levels. In our study, we show that low cholesterol levels were attributable to enhanced bile acid synthesis in combination with reduced cholesterol absorption. Hepatic cholesterol 7alpha-hydroxylase (CYP7A1), the rate-limiting enzyme catalyzing the conversion of cholesterol to bile acids, plays an important role in the removal of excess cholesterol from the body. We suggest that by reducing activity of Akt activated polyamine catabolism increased the stability and activity of peroxisome proliferator-activated receptor gamma co-activator 1alpha, the critical activator of CYP7A1. This is supported by our finding that the treatment with SSAT activator, N (1) ,N(11)-diethylnorspermine, reduced significantly the amount of phosphorylated (active) Akt in HepG2 cells. In summary, activated-polyamine catabolism is a novel mechanism to regulate bile acid synthesis. Therefore, polyamine catabolism could be a potential therapeutic target to control hepatic CYP7A1 expression.
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Affiliation(s)
- Eija Pirinen
- Department of Medicine, University of Kuopio, P.O. Box 1777, 70211, Kuopio, Finland
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Tardiff RG, Carson ML, Sweeney LM, Kirman CR, Tan YM, Andersen M, Bevan C, Gargas ML. Derivation of a drinking water equivalent level (DWEL) related to the maximum contaminant level goal for perfluorooctanoic acid (PFOA), a persistent water soluble compound. Food Chem Toxicol 2009; 47:2557-89. [DOI: 10.1016/j.fct.2009.07.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Revised: 07/15/2009] [Accepted: 07/16/2009] [Indexed: 01/09/2023]
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Arai T, Kim HJ, Chiba H, Matsumoto A. Interaction of fenofibrate and fish oil in relation to lipid metabolism in mice. J Atheroscler Thromb 2009; 16:283-91. [PMID: 19556727 DOI: 10.5551/jat.e463] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
AIM The aim of our study is to elucidate the interactive effects on lipid metabolism of fenofibrate and two fish oils with EPA and DHA contents in mice. METHODS Female C57BL/6J mice were fed purified experimental diets containing safflower oil (SO), EPA-rich menhaden oil (MO) or DHA-rich tuna oil (TO) with or without 0.1% fenofibrate for 8 weeks. At the end of the experiments, we measured plasma lipids and hepatic triglycerides and cholesterol, and the hepatic mRNA expression of lipogenic and lipidolytic genes. RESULTS Plasma TG levels fell in the group fed MO or TO alone and fell significantly in all fenofibrate-treated groups. Although plasma total cholesterol levels fell significantly in fish oil-fed groups, fenofibrate treatments increased significantly plasma total cholesterol levels in these fish oil groups, but not in the group fed SO alone; however, hepatic triglyceride and total cholesterol levels markedly decreased in MO-or TO-fed mice. In lipid synthesis, the hepatic mRNA level of SREBP-1c was not reduced in either fish oil group; however, Insig-1 mRNA decreased in MO and TO feeding groups by about half and FAS or SCD-1 mRNA decreased significantly in MO and TO feeding groups, compared with the SO feeding group. In both fish oil groups, SREBP-2 mRNA decreased significantly and HMG-CoA reductase mRNA also decreased with/without fenofibrate. On the other hand, fenofibrate supplementation significantly induced the mRNA expression of AOX and UCP-2, which play a role in lipid catabolism, in all diets. CYP7A1 mRNA increased markedly in mice fed MO diet with fenofibrate, compared with TO diet with fenofibrate. CONCLUSION These data suggest that differences in dietary contents of EPA and DHA do not influence the inhibition of lipogenesis, and that fenofibrate supplementation stimulates fatty acid oxidation, regardless of the oil type; however, cholesterol catabolism was induced by a combination of EPA-rich fish oil and fenofibrate, which suggests that EPA has a greater synergistic ability for cholesterol catabolism induction by fenofibrate than DHA.
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Affiliation(s)
- Takeshi Arai
- Faculty of Pharmaceutical Sciences, Josai University, Sakado, Saitama 350-0295, Japan
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31
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Arzuaga X, Ren N, Stromberg A, Black EP, Arsenescu V, Cassis LA, Majkova Z, Toborek M, Hennig B. Induction of gene pattern changes associated with dysfunctional lipid metabolism induced by dietary fat and exposure to a persistent organic pollutant. Toxicol Lett 2009; 189:96-101. [PMID: 19467301 DOI: 10.1016/j.toxlet.2009.05.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Revised: 05/08/2009] [Accepted: 05/12/2009] [Indexed: 12/25/2022]
Abstract
Environmental modulators of chronic diseases can include nutrition, lifestyle, as well as exposure to environmental toxicants such as persistent organic pollutants. A study was designed to explore gene expression changes as affected by both dietary fat and exposure to the polychlorinated biphenyl PCB77. Mice were fed for 4 months diets enriched with high-linoleic acid oils (20% and 40% as calories), and during the last 2 months half of each group was exposed to PCB77. Ribonucleic acids (RNA) were extracted from liver tissue to determine gene expression changes using DNA microarray analysis. Our microarray data demonstrated a significant interaction between dietary fat and PCB exposure. Deregulated genes were organized into patterns describing the interaction of diet and PCB exposure. Annotation of the deregulated genes matching these probe sets revealed a significant high-fat mediated induction of genes associated with fatty acid metabolism, triacylglycerol synthesis and cholesterol catabolism, which was down-regulated in animals exposed to PCB77. Many of these genes are regulated by the peroxisome proliferator activated receptor-alpha (PPARalpha), and changes in PPARalpha gene expression followed the same gene pattern as described above. These results provide insight into molecular mechanisms of how dietary fat can interact with environmental pollutants to compromise lipid metabolism.
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Affiliation(s)
- Xabier Arzuaga
- Molecular and Cell Nutrition Laboratory, Department of Animal and Food Sciences, University of Kentucky, Lexington, KY 40536, USA
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Klaunig JE, Babich MA, Baetcke KP, Cook JC, Corton JC, David RM, DeLuca JG, Lai DY, McKee RH, Peters JM, Roberts RA, Fenner-Crisp PA. PPARα Agonist-Induced Rodent Tumors: Modes of Action and Human Relevance. Crit Rev Toxicol 2008; 33:655-780. [PMID: 14727734 DOI: 10.1080/713608372] [Citation(s) in RCA: 433] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Widely varied chemicals--including certain herbicides, plasticizers, drugs, and natural products--induce peroxisome proliferation in rodent liver and other tissues. This phenomenon is characterized by increases in the volume density and fatty acid oxidation of these organelles, which contain hydrogen peroxide and fatty acid oxidation systems important in lipid metabolism. Research showing that some peroxisome proliferating chemicals are nongenotoxic animal carcinogens stimulated interest in developing mode of action (MOA) information to understand and explain the human relevance of animal tumors associated with these chemicals. Studies have demonstrated that a nuclear hormone receptor implicated in energy homeostasis, designated peroxisome proliferator-activated receptor alpha (PPARalpha), is an obligatory factor in peroxisome proliferation in rodent hepatocytes. This report provides an in-depth analysis of the state of the science on several topics critical to evaluating the relationship between the MOA for PPARalpha agonists and the human relevance of related animal tumors. Topics include a review of existing tumor bioassay data, data from animal and human sources relating to the MOA for PPARalpha agonists in several different tissues, and case studies on the potential human relevance of the animal MOA data. The summary of existing bioassay data discloses substantial species differences in response to peroxisome proliferators in vivo, with rodents more responsive than primates. Among the rat and mouse strains tested, both males and females develop tumors in response to exposure to a wide range of chemicals including DEHP and other phthalates, chlorinated paraffins, chlorinated solvents such as trichloroethylene and perchloroethylene, and certain pesticides and hypolipidemic pharmaceuticals. MOA data from three different rodent tissues--rat and mouse liver, rat pancreas, and rat testis--lead to several different postulated MOAs, some beginning with PPARalpha activation as a causal first step. For example, studies in rodent liver identified seven "key events," including three "causal events"--activation of PPARalpha, perturbation of cell proliferation and apoptosis, and selective clonal expansion--and a series of associative events involving peroxisome proliferation, hepatocyte oxidative stress, and Kupffer-cell-mediated events. Similar in-depth analysis for rat Leydig-cell tumors (LCTs) posits one MOA that begins with PPARalpha activation in the liver, but two possible pathways, one secondary to liver induction and the other direct inhibition of testicular testosterone biosynthesis. For this tumor, both proposed pathways involve changes in the metabolism and quantity of related hormones and hormone precursors. Key events in the postulated MOA for the third tumor type, pancreatic acinar-cell tumors (PACTs) in rats, also begin with PPARalpha activation in the liver, followed by changes in bile synthesis and composition. Using the new human relevance framework (HRF) (see companion article), case studies involving PPARalpha-related tumors in each of these three tissues produced a range of outcomes, depending partly on the quality and quantity of MOA data available from laboratory animals and related information from human data sources.
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Affiliation(s)
- James E Klaunig
- Indiana University School of Medicine, Indianapolis, IN, USA
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Zhang Y, Xie ML, Xue J, Gu ZL. Osthole regulates enzyme protein expression of CYP7A1 and DGAT2 via activation of PPARalpha/gamma in fat milk-induced fatty liver rats. JOURNAL OF ASIAN NATURAL PRODUCTS RESEARCH 2008; 10:807-812. [PMID: 18696335 DOI: 10.1080/10286020802102303] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Osthole (1), an active constituent isolated from Cnidium monnieri (L.) Cusson, has been used in the treatment of diseases for many years in clinical. The aim of this present study was to determine the effect of 1 on protein expression of PPARalpha/gamma and related target molecules such as CYP7A and DGAT protein expression in the liver of hyperlipidemic fatty liver (HFL) rats, and to investigate the possible mechanism of treating HFL.
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Affiliation(s)
- Yan Zhang
- Department of Pharmacology, Medical School of Soochow University, Suzhou, China
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Rosen MB, Thibodeaux JR, Wood CR, Zehr RD, Schmid JE, Lau C. Gene expression profiling in the lung and liver of PFOA-exposed mouse fetuses. Toxicology 2007; 239:15-33. [PMID: 17681415 DOI: 10.1016/j.tox.2007.06.095] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2007] [Revised: 06/06/2007] [Accepted: 06/15/2007] [Indexed: 11/26/2022]
Abstract
Perfluorooctanoic acid (PFOA) is a stable perfluoroalkyl acid used to synthesize fluoropolymers during the manufacture of a wide variety of products. Concerns have been raised over the potential health effects of PFOA because it is persistent in the environment and can be detected in blood and other tissues of many animal species, including humans. PFOA has also been shown to induce growth deficits and mortality in murine neonates. To better understand the mechanism of PFOA induced developmental toxicity, lung and liver gene expression profiling was conducted in PFOA-exposed full-term mouse fetuses. Thirty timed-pregnant CD-1 mice were orally dosed from gestation days 1-17 with either 0, 1, 3, 5, or 10mg/(kgday) PFOA in water. At term, fetal lung and liver were collected, total RNA prepared, and samples pooled from three fetuses per litter. Five biological replicates consisting of individual litter samples were then evaluated for each treatment group using Affymetrix mouse 430_2 microarrays. The expression of genes related to fatty acid catabolism was altered in both the fetal liver and lung. In the fetal liver, the effects of PFOA were robust and also included genes associated with lipid transport, ketogenesis, glucose metabolism, lipoprotein metabolism, cholesterol biosynthesis, steroid metabolism, bile acid biosynthesis, phospholipid metabolism, retinol metabolism, proteosome activation, and inflammation. These changes are consistent with transactivation of PPARalpha, although, with regard to bile acid biosynthesis and glucose metabolism, non-PPARalpha related effects were suggested as well. Additional studies will be needed to more thoroughly address the role of PPARalpha, and other nuclear receptors, in PFOA mediated developmental toxicity.
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Affiliation(s)
- Mitchell B Rosen
- Reproductive Toxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
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Ng VY, Huang Y, Reddy LM, Falck JR, Lin ET, Kroetz DL. Cytochrome P450 eicosanoids are activators of peroxisome proliferator-activated receptor alpha. Drug Metab Dispos 2007; 35:1126-34. [PMID: 17431031 DOI: 10.1124/dmd.106.013839] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cytochrome P450 (P450) eicosanoids regulate vascular tone, renal tubular transport, cellular proliferation, and inflammation. Both the CYP4A omega-hydroxylases, which catalyze 20-hydroxyeicosatetraenoic acid (20-HETE) formation, and soluble epoxide hydrolase (sEH), which catalyzes epoxyeicosatrienoic acid (EET) degradation to the dihydroxyeicosatrienoic acids (DHETs), are induced upon activation of peroxisome proliferator-activated receptor alpha (PPARalpha) by fatty acids and fibrates. In contrast, the CYP2C epoxygenases, which are responsible for EET formation, are repressed after fibrate treatment. We show here that P450 eicosanoids can bind to and activate PPARalpha and result in the modulation of PPARalpha target gene expression. In transactivation assays, 14,15-DHET, 11,2-EET, and 20-HETE were potent activators of PPARalpha. Gel shift assays showed that EETs, DHETs, and 20-HETE induced PPARalpha-specific binding to its cognate response element. Expression of apolipoprotein A-I was decreased 70% by 20-HETE, whereas apolipoprotein A-II expression was increased up to 3-fold by 11,12-EET, 14,15-DHET, and 20-HETE. In addition, P450 eicosanoids induced CYP4A1, sEH, and CYP2C11 expression, suggesting that they can regulate their own levels. Given that P450 eicosanoids have multiple cardiovascular effects, pharmacological modulation of their formation and/or degradation may yield therapeutic benefits.
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Affiliation(s)
- Valerie Y Ng
- Department of Biopharmaceutical Sciences, University of California San Francisco, San Francisco, CA 94143-2911, USA
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Hamelet J, Demuth K, Paul JL, Delabar JM, Janel N. Hyperhomocysteinemia due to cystathionine beta synthase deficiency induces dysregulation of genes involved in hepatic lipid homeostasis in mice. J Hepatol 2007; 46:151-9. [PMID: 17030070 DOI: 10.1016/j.jhep.2006.07.028] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2006] [Revised: 06/17/2006] [Accepted: 07/05/2006] [Indexed: 12/04/2022]
Abstract
BACKGROUND/AIMS Cystathionine beta synthase (CBS) deficiency leads to severe hyperhomocysteinemia, which confers diverse clinical manifestations, notably fatty liver. Recently, abnormal lipid metabolism has been demonstrated in CBS-deficient mice, a murine model of severe hyperhomocysteinemia. To gain further insights into effects of CBS deficiency on hepatic cholesterol metabolism, the expression of hepatic genes involved in biosynthesis, uptake and efflux was determined in CBS-deficient mice. METHODS Gene expression analysis was performed on liver of CBS-deficient mice using quantitative real-time PCR. RESULTS We found that CBS-deficiency in liver mice significantly increases expression of genes induced by endoplasmic reticulum stress and genes that regulate the expression of enzymes required for cholesterol and fatty acid biosynthesis and uptake, notably the scavenger receptor class B type I (SR-BI), concomitant with overexpression of SR-BI at the protein level. Moreover, we also found increased mRNA levels of ABCG5, ABCG8, ABCG1 and ABCA1, which play important roles in reverse cholesterol transport, associated with an upregulation of liver X receptors and a downregulation of the peroxisome proliferators-activated receptor alpha. CONCLUSIONS We found that several ATP-binding cassette transporters and nuclear hormone receptors involved in liver lipid homeostasis are differentially expressed in liver of CBS-deficient mice.
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Affiliation(s)
- Julien Hamelet
- EA 3508, Université Paris 7 - Denis Diderot, Case 7104, 2 Place Jussieu, 75251 Paris cedex 05, France
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Chen CW, Cheng HH. A rice bran oil diet increases LDL-receptor and HMG-CoA reductase mRNA expressions and insulin sensitivity in rats with streptozotocin/nicotinamide-induced type 2 diabetes. J Nutr 2006; 136:1472-6. [PMID: 16702306 DOI: 10.1093/jn/136.6.1472] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A rice bran oil (RBO) diet can reduce plasma lipids; this was attributed to the specific components, gamma-oryzanol and gamma-tocotrienol, which individually were shown to be hypocholesterolemic; however, the mechanism of their effects on diabetic hyperlipidemia and the development of diabetes is not known. Rats with streptozotocin/nicotinamide-induced type 2 diabetes were divided into control, RO10, and RO15 groups, and fed cholesterol-free diets containing 0, 10, and 15 g RBO with 0, 352, and 528 g gamma-oryzanol and 0, 6.0 and 9.0 mg gamma-tocotrienol/100 g diet for 4 wk. Diabetic rats fed the RBO diet had greater insulin sensitivity (P = 0.02) than rats fed the control diet. Diabetic rats fed the RBO diet also had lower plasma triglyceride (P = 0.003), LDL cholesterol (P = 0.028), and hepatic triglyceride concentrations (P = 0.04), as well as greater fecal neutral sterol and bile acid excretion than those fed the control diet. After 4 wk, there was an approximately 100% (P < 0.001) increase in the abundance of hepatic cholesterol 7alpha-hydroxylase, an 89% (P < 0.001) increase in the hepatic LDL-receptor, and a 50% (P < 0.001) increase in hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase mRNA in rats fed the RBO diet compared with those fed the control diet. These findings support the conclusion that a rice bran oil-containing diet can significantly suppress hyperlipidemic and hyperinsulinemic responses in diabetic rats. The high contents of gamma-oryzanol and gamma-tocotrienol in RBO can lead to increased fecal neutral sterol and bile acid excretion, via upregulation of cholesterol synthesis and catabolism.
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Affiliation(s)
- Chia-Wen Chen
- Graduate Institute of Pharmacy, Taipei Medical University, Taipei, Taiwan, ROC
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Cheema SK, Agarwal-Mawal A, Murray CM, Tucker S. Lack of stimulation of cholesteryl ester transfer protein by cholesterol in the presence of a high-fat diet. J Lipid Res 2005; 46:2356-66. [PMID: 16106052 DOI: 10.1194/jlr.m500051-jlr200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cholesteryl ester transfer protein (CETP) is a key protein involved in the reverse cholesterol transport pathway. The regulation of CETP by dietary fats is not clearly understood. Transgenic mice expressing human CETP under the control of its natural flanking region were fed low- or high-fat diets enriched in monounsaturated fatty acids (MUFAs) or saturated fatty acids in the presence or absence of cholesterol. Addition of cholesterol to the low-fat MUFA diet increased CETP activity and mRNA expression, whereas addition of cholesterol to the high-fat MUFA diet led to a decrease in CETP activity and mRNA expression. In SW 872 cells, oleic acid and cholesterol stimulated CETP gene expression when given alone. However, addition of fatty acids along with cholesterol interfered with the stimulatory effect of cholesterol on CETP gene regulation. Cholesterol-mediated stimulation of CETP involves the transcription factor liver X receptor alpha (LXRalpha). High-fat MUFA diets inhibited the expression of LXRalpha, and addition of cholesterol to the high-fat MUFA diet did not rescue LXRalpha expression. Therefore, we present evidence for the first time that inhibition of LXRalpha expression by a high-fat MUFA diet leads to inhibition of CETP stimulation by cholesterol.
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Affiliation(s)
- Sukhinder Kaur Cheema
- Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3X9, Canada.
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Hoekstra M, Out R, Kruijt JK, Van Eck M, Van Berkel TJC. Diet induced regulation of genes involved in cholesterol metabolism in rat liver parenchymal and Kupffer cells. J Hepatol 2005; 42:400-7. [PMID: 15710224 DOI: 10.1016/j.jhep.2004.11.032] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2004] [Revised: 11/02/2004] [Accepted: 11/10/2004] [Indexed: 12/04/2022]
Abstract
BACKGROUND/AIMS Feeding rodents atherogenic diets enriched in cholesterol or cholic acid changes hepatic cholesterol metabolism. In the present study, the effect of an atherogenic diet enriched in cholesterol and cholic acid on cellular hepatic cholesterol metabolism was studied. METHODS Gene and protein expression analysis was performed on parenchymal, endothelial, and Kupffer cells isolated from rats fed a chow or atherogenic diet using quantitative real-time PCR and immunoblotting, respectively. RESULTS The atherogenic diet raised the serum cholesterol concentration 11-fold, mostly in the VLDL fraction, and led to heavy lipid loading of rat liver parenchymal and Kupffer cells. Only moderate changes in the expression of genes involved in cholesterol metabolism were observed in parenchymal cells on the diet, while PPAR delta expression was 6.8-fold decreased. Kupffer cells, however, showed a highly adaptive response with a 2- to 9-fold induction of SR-BI, ABCA1, and ABCG5/G8, and an 82-fold induction in CYP7A1 mRNA expression, respectively. CONCLUSIONS Heavy lipid loading of parenchymal cells leads to moderate gene expression changes, while Kupffer cells respond in a highly adaptive fashion by stimulating the expression of genes involved in cholesterol metabolism and transport.
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Affiliation(s)
- Menno Hoekstra
- Division of Biopharmaceutics, Leiden/Amsterdam Center for Drug Research, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands.
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Handschin C, Gnerre C, Fraser DJ, Martinez-Jimenez C, Jover R, Meyer UA. Species-specific mechanisms for cholesterol 7alpha-hydroxylase (CYP7A1) regulation by drugs and bile acids. Arch Biochem Biophys 2005; 434:75-85. [PMID: 15629111 DOI: 10.1016/j.abb.2004.10.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2004] [Revised: 10/06/2004] [Indexed: 01/29/2023]
Abstract
The gene encoding cholesterol 7alpha-hydroxylase (CYP7A1) is tightly regulated in order to control intrahepatic cholesterol and bile acid levels. Ligands of the xenobiotic-sensing pregnane X receptor inhibit CYP7A1 expression. To retrace the evolution of the molecular mechanisms underlying CYP7A1 inhibition, we used a chicken hepatoma cell system that retains the ability to be induced by phenobarbital and other drugs. Whereas bile acids regulate CYP7A1 via small heterodimer partner and liver receptor homolog-1, mRNA expression of these nuclear receptors is unchanged by xenobiotics. Instead, drugs repress chicken hepatic nuclear factor 4alpha (HNF4alpha) transcript levels concomitant with a reduction in CYP7A1 expression. Importantly, no reduction of HNF4alpha levels is found in mouse liver in vivo and in human primary hepatocyte cultures, respectively. Thus, besides the importance of HNF4alpha in CYP7A1 regulation in all species, birds and mammals use different signaling pathways to adjust CYP7A1 levels after exposure to xenobiotics.
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MESH Headings
- Animals
- Bile Acids and Salts/metabolism
- Bile Acids and Salts/pharmacology
- Cells, Cultured
- Chickens
- Cholesterol 7-alpha-Hydroxylase/genetics
- Cholesterol 7-alpha-Hydroxylase/metabolism
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Gene Expression Regulation, Enzymologic/drug effects
- Hepatocyte Nuclear Factor 4
- Hepatocytes/drug effects
- Hepatocytes/metabolism
- Humans
- In Vitro Techniques
- Mice
- Mice, Knockout
- Molecular Sequence Data
- Phenobarbital/pharmacology
- Phosphoproteins/genetics
- Phosphoproteins/metabolism
- Pregnane X Receptor
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Cytoplasmic and Nuclear/deficiency
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/metabolism
- Receptors, Steroid/deficiency
- Receptors, Steroid/genetics
- Receptors, Steroid/metabolism
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Signal Transduction
- Species Specificity
- Transcription Factors/genetics
- Transcription Factors/metabolism
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Affiliation(s)
- Christoph Handschin
- Division of Pharmacology/Neurobiology, Biozentrum of the University of Basel, Klingelbergstrasse 50-70, CH-4056 Basel, Switzerland
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41
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Fatehi-Hassanabad Z, Chan CB. Transcriptional regulation of lipid metabolism by fatty acids: a key determinant of pancreatic beta-cell function. Nutr Metab (Lond) 2005; 2:1. [PMID: 15634355 PMCID: PMC544854 DOI: 10.1186/1743-7075-2-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2004] [Accepted: 01/05/2005] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND: Optimal pancreatic beta-cell function is essential for the regulation of glucose homeostasis in both humans and animals and its impairment leads to the development of diabetes. Type 2 diabetes is a polygenic disease aggravated by environmental factors such as low physical activity or a hypercaloric high-fat diet. RESULTS: Free fatty acids represent an important factor linking excess fat mass to type 2 diabetes. Several studies have shown that chronically elevated free fatty acids have a negative effect on beta-cell function leading to elevated insulin secretion basally but with an impaired response to glucose. The transcription factors PPARalpha, PPARgamma and SREBP-1c respond to changing fat concentrations in tissues, thereby coordinating the genomic response to altered metabolic conditions to promote either fat storage or catabolism. These transcription factors have been identified in beta-cells and it appears that each may exert influence on beta-cell function in health and disease. CONCLUSION: The role of the PPARs and SREBP-1c as potential mediators of lipotoxicity is an emerging area of interest.
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Affiliation(s)
- Zahra Fatehi-Hassanabad
- Department of Biomedical Sciences, University of Prince Edward Island, 550 University Avenue, Charlottetown, PE C1A 4P3 Canada
| | - Catherine B Chan
- Department of Biomedical Sciences, University of Prince Edward Island, 550 University Avenue, Charlottetown, PE C1A 4P3 Canada
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42
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Abstract
Dietary fat has a dual role in human physiology: a) it functions as a source of energy and structural components for cells; b) it functions as a regulator of gene expression that impacts lipid, carbohydrate, and protein metabolism, as well as cell growth and differentiation. Fatty acid effects on gene expression are cell-specific and influenced by fatty acid structure and metabolism. Fatty acids interact with the genome through several mechanisms. They regulate the activity or nuclear abundance of several transcription factors, including PPAR, LXR, HNF-4, NFkappaB, and SREBP. Fatty acids or their metabolites bind directly to specific transcription factors to regulate gene transcription. Alternatively, fatty acids indirectly act on gene expression through their effects on a) specific enzyme-mediated pathways, such as cyclooxygenase, lipoxygenase, protein kinase C, or sphingomyelinase signal transduction pathways; or b) pathways that involve changes in membrane lipid/lipid raft composition that affect G-protein receptor or tyrosine kinase-linked receptor signaling. Further definition of these fatty acid-regulated pathways will provide insight into the role dietary fat plays in human health and the onset and progression of several chronic diseases, like coronary artery disease and atherosclerosis, dyslipidemia and inflammation, obesity and diabetes, cancer, major depressive disorders, and schizophrenia.
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Affiliation(s)
- Donald B Jump
- Department of Physiology, Michigan State University, East Lansing, Michigan 48824, USA.
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43
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Abstract
The last decade provided evidence that major (glucose, fatty acids, amino acids) or minor (iron, vitamin, etc.) dietary constituents regulated gene expression in an hormonal-independent manner. This review focuses on molecular mechanisms by which fatty acids control the expression genes encoding regulatory protein involved in their own metabolism. Nonesterified fatty acids or their CoA derivatives seem to be the main signals involved in the transcriptional effect of long-chain fatty acids. The effects of fatty acids are mediated either directly owing to their specific binding to various nuclear receptors (PPAR, LXR, HNF-4alpha) leading to changes in the trans-activating activity of these transcription factors, or indirectly as the result of changes in the abundance of regulatory transcription factors (SREBP-1c, ChREBP, etc.). The relative contribution of each transcription factor in fatty acid-induced positive or negative gene expression is discussed.
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Affiliation(s)
- Jean-Paul Pégorier
- Département d'Endocrinologie, Institut Cochin, INSERM U567, CNRS UMR8104, IFR Alfred JOST, Faculté de Médecine Cochin-Port-Royal, 24 rue du Faubourg Saint Jacques, 75014 Paris, France.
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44
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Bisschop PH, Bandsma RHJ, Stellaard F, ter Harmsel A, Meijer AJ, Sauerwein HP, Kuipers F, Romijn JA. Low-fat, high-carbohydrate and high-fat, low-carbohydrate diets decrease primary bile acid synthesis in humans. Am J Clin Nutr 2004; 79:570-6. [PMID: 15051599 DOI: 10.1093/ajcn/79.4.570] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Dietary fat content influences bile salt metabolism, but quantitative data from controlled studies in humans are scarce. OBJECTIVE The objective of the study was to establish the effect of dietary fat content on the metabolism of primary bile salts. DESIGN The effects of eucaloric extremely low-fat (0%), intermediate-fat (41%; control diet), and extremely high-fat (83%) diets on kinetic values of cholate and chenodeoxycholate metabolism were determined after 11 d by using stable isotope dilution in 6 healthy men. All diets contained identical amounts of cholesterol. RESULTS The total primary bile salt pool size was not significantly affected by dietary fat content, although the chenodeoxycholate pool was significantly higher during the low-fat diet. Fractional turnover rates of both primary bile salts were 30-50% lower during the low- and high-fat diets than during the control diet. Total hepatic bile salt synthesis was approximately 30% lower during both the high- and low-fat diets, but synthesis rates of the 2 primary bile salts were differentially affected. The molar ratio of cholate to total bile salt synthesis increased from 0.50 +/- 0.05 ( +/- SD) to 0.59 +/- 0.05 and 0.66 +/- 0.04 with increasing fat intake, whereas the molar ratio of chenodeoxycholate to total bile salt synthesis decreased from 0.50 +/- 0.05 to 0.41 +/- 0.05 and 0.34 +/- 0.04. The relative concentration of deoxycholate in plasma increased during the low-fat period, which indicated increased absorption from the colon. CONCLUSIONS Both low- and high-fat diets reduce the synthesis and turnover rates of primary bile salts in humans, although probably through different mechanisms, and consequently they affect the removal of cholesterol from the body.
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Affiliation(s)
- Peter H Bisschop
- Department of Endocrinology & Metabolism, Academic Medical Center, University of Amsterdam, Netherlands.
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45
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Gbaguidi GF, Agellon LB. The inhibition of the human cholesterol 7alpha-hydroxylase gene (CYP7A1) promoter by fibrates in cultured cells is mediated via the liver x receptor alpha and peroxisome proliferator-activated receptor alpha heterodimer. Nucleic Acids Res 2004; 32:1113-21. [PMID: 14960721 PMCID: PMC373396 DOI: 10.1093/nar/gkh260] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In previous work, we showed that the binding of the liver x receptor alpha:peroxisome proliferator-activated receptor alpha (LXRalpha:PPARalpha) heterodimer to the murine Cyp7a1 gene promoter antagonizes the stimulatory effect of their respective ligands. In this study, we determined if LXRalpha:PPARalpha can also regulate human CYP7A1 gene promoter activity. Co-expression of LXRalpha and PPARalpha in McArdle RH7777 hepatoma cells decreased the activity of the human CYP7A1 gene promoter in response to fibrates and 25-hydroxycholesterol. In vitro, the human CYP7A1 Site I bound LXRalpha:PPARalpha, although with substantially less affinity compared with the murine Cyp7a1 Site I. The binding of LXRalpha:PPARalpha to human CYP7A1 Site I was increased in the presence of either LXRalpha or PPARalpha ligands. In HepG2 hepatoblastoma cells, fibrates and 25-hydroxycholesterol inhibited the expression of the endogenous CYP7A1 gene as well as the human CYP7A1 gene promoter when co-transfected with plasmids encoding LXRalpha and PPARalpha. However, a derivative of the human CYP7A1 gene promoter that contains a mutant form of Site I that does not bind LXRalpha:PPARalpha was not inhibited by WY 14,643 or 25-hydroxycholesterol in both McArdle RH7777 and HepG2 cells. The ligand-dependent recruitment of LXRalpha:PPARalpha heterodimer onto the human CYP7A1 Site I can explain the inhibition of the human CYP7A1 gene promoter in response to fibrates and 25-hydroxycholesterol.
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Affiliation(s)
- G Franck Gbaguidi
- Canadian Institutes of Health Research Group in Molecular and Cell Biology of Lipids and Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2S2, Canada
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46
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Drover VAB, Agellon LB. Regulation of the human cholesterol 7alpha-hydroxylase gene (CYP7A1) by thyroid hormone in transgenic mice. Endocrinology 2004; 145:574-81. [PMID: 14592954 DOI: 10.1210/en.2003-0993] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Thyroid hormones exert significant changes in the metabolism of bile acids. However, in humans, the effect of thyroid hormone on cholesterol 7alpha-hydroxylase (cyp7a), the rate- controlling enzyme in the classical bile acid biosynthetic pathway, remains poorly understood and has been difficult to study directly in vivo. Previous studies from our laboratory have shown that the activity of the human cholesterol 7alpha-hydroxylase gene promoter is repressed by T(3) in cultured cells. Accordingly, we hypothesized that T(3) would negatively regulate human CYP7A1 gene expression in vivo. We tested this hypothesis by inducing hypo- and hyperthyroidism in transgenic mice expressing the human CYP7A1 gene. Hypothyroidism did not affect the abundance of human cyp7a mRNA in transgenic mice. In hyperthyroid male mice, human cyp7a mRNA abundance was decreased. No significant change in cyp7a mRNA abundance was observed in hyperthyroid female mice. Gender differences in the amount of cholesterol and bile acids in gallbladder bile were also observed. The data indicate that thyroid hormone can repress the human CYP7A1 gene in transgenic mice, but this effect is dependent on gender in this in vivo model.
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Affiliation(s)
- Victor A B Drover
- Canadian Institutes of Health Research Group in Molecular and Cell Biology of Lipids, Heritage Medical Research Centre, University of Alberta, Edmonton, Alberta, Canada T6G 2S2
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47
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Roglans N, Vázquez-Carrera M, Alegret M, Novell F, Zambón D, Ros E, Laguna JC, Sánchez RM. Fibrates modify the expression of key factors involved in bile-acid synthesis and biliary-lipid secretion in gallstone patients. Eur J Clin Pharmacol 2003; 59:855-61. [PMID: 14685799 DOI: 10.1007/s00228-003-0704-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2003] [Accepted: 11/07/2003] [Indexed: 11/28/2022]
Abstract
AIMS Fibrate treatment induces adverse changes in biliary-lipid and bile-acid composition. Since the molecular mechanisms underlying these changes are still unclear, we have investigated the effect of fibrate treatment on key factors involved in bile-acid synthesis, biliary-lipid secretion and cholesterol metabolism in gallstone patients. METHODS Patients with uncomplicated gallstones and a serum level of low-density lipoprotein (LDL) cholesterol >130 mg/dl were randomly assigned to open-label treatment with bezafibrate, fenofibrate, gemfibrozil, or placebo for 8 weeks before elective cholecystectomy. A liver specimen was obtained at operation, and the mRNA relative levels for cholesterol 7alpha-hydroxylase (CYP7A1), hepatocyte nuclear factor-4 (HNF-4), ATP-binding cassette transporters MDR3, ABCG5, and ABCG8, human homologue scavenger receptor BI, sterol response element binding protein-2 (SREBP-2), 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase and LDL receptor were determined by means of reverse-transcriptase polymerase chain reaction. RESULTS Bezafibrate, fenofibrate and gemfibrozil significantly reduced CYP7A1 mRNA levels. The three fibrates tested raised the mRNA levels of ABCG5 and SREBP-2, but only bezafibrate induced significant changes. Although MDR-3 mRNA levels were slightly increased by the three fibrates, no significant differences were obtained. CONCLUSIONS These results show for the first time that fibrate administration to humans downregulates CYP7A1. Although ABCG5 and SREBP-2 mRNA levels were slightly increased by all treatment groups, only bezafibrate induced significant changes.
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Affiliation(s)
- Núria Roglans
- Pharmacology Unit, Faculty of Pharmacy, University of Barcelona, Barcelona, Spain
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48
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Pawar A, Botolin D, Mangelsdorf DJ, Jump DB. The role of liver X receptor-alpha in the fatty acid regulation of hepatic gene expression. J Biol Chem 2003; 278:40736-43. [PMID: 12917410 DOI: 10.1074/jbc.m307973200] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Liver X receptors (LXR) alpha and beta play an important role in regulating the expression of genes involved in hepatic bile and fatty acid synthesis, glucose metabolism, as well as sterol efflux. Studies with human embryonic kidney 293 cells indicate that unsaturated fatty acids interfere with oxysterols binding to LXR and antagonize oxysterol-induced LXRalpha activity. In this report, we evaluated the effects of unsaturated fatty acids on LXR-regulated hepatic gene expression. The LXR agonist, T1317, induced mRNAs encoding sterol regulatory element-binding protein 1c (SREBP-1c) and two SREBP-1c-regulated lipogenic genes, e.g. fatty-acid synthase and the S14 protein in primary hepatocytes. Treatment of hepatocytes with eicosapentaenoic acid (20:5n-3) suppressed these mRNAs in the absence and presence of T1317. The cis-regulatory elements targeted by T1317 were not required for fatty-acid suppression of FAS or S14 promoter activity. In contrast to SREBP-1-regulated lipogenic genes, 20:5n-3 had no effect on the T1317 induction of ABCG5 or ABCG8 in the rat hepatoma cell line, FTO-2B. These two genes require LXR but not SREBP-1c for their expression. Feeding rats a diet supplemented with fish oil suppressed hepatic SREBP-1c-regulated genes and induced PPARalpha-regulated genes but had no effect on the LXR-regulated transcripts, CYP7A1, ABCG5, or ABCG8. Transfection studies, using either full-length hLXRalpha or a chimera containing only the LXRalpha ligand binding domain, indicate that a wide array of unsaturated fatty acids had little effect on LXRalpha activity in primary hepatocytes or FTO-2B. These studies suggest that LXRalpha is not a target for unsaturated fatty acid regulation in primary rat hepatocytes or in liver. Thus, oxysterol/LXR-mediated regulation of transcripts involved in bile acid synthesis or sterol efflux appear insensitive to dietary unsaturated fatty acids. The unsaturated fatty acid suppression of SREBP-1 and its targeted lipogenic genes is independent of LXRalpha
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Affiliation(s)
- Anjali Pawar
- Department of Physiology, Michigan State University, East Lansing, Michigan 48824, USA
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49
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Pégorier JP, Le May C. Régulation de l’expression génique par les acides gras. NUTR CLIN METAB 2003. [DOI: 10.1016/s0985-0562(03)00027-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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50
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Gbaguidi GF, Agellon LB. The atypical interaction of peroxisome proliferator-activated receptor alpha with liver X receptor alpha antagonizes the stimulatory effect of their respective ligands on the murine cholesterol 7alpha-hydroxylase gene promoter. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1583:229-36. [PMID: 12117567 DOI: 10.1016/s1388-1981(02)00217-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Cholesterol 7alpha-hydroxylase (cyp7a) mediates cholesterol elimination in the liver by catalyzing the first and rate-limiting step in the conversion of cholesterol into bile acids. Peroxisome proliferator-activated receptor alpha (PPARalpha; NR1C1) and liver X receptor alpha (LXRalpha; NR1H3) are two nuclear receptors that stimulate the murine Cyp7a1 gene. Here we report that co-expression of PPARalpha and LXRalpha in hepatoma cells abolishes the stimulation of Cyp7a1 gene promoter in response to their respective agonists. PPARalpha and LXRalpha form an atypical heterodimer that binds to two directly adjacent hexameric sequences localized within overlapping PPARalpha and LXRalpha response elements (termed Site I), antagonizing the interaction of PPARalpha:retinoid X receptor alpha (RXRalpha) or RXRalpha:LXRalpha with the Cyp7a1 gene promoter. Mutations within either hexameric sequences that specifically abolished LXRalpha:PPARalpha heterodimer binding to the murine Cyp7a1 Site I also relieved promoter inhibition. The LXRalpha:PPARalpha heterodimer may be important in coordinating the expression of genes that encode proteins involved in metabolism of fats and cholesterol.
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Affiliation(s)
- G Franck Gbaguidi
- Canadian Institutes of Health Research Group in Molecular and Cell Biology of Lipids and Department of Biochemistry, 328 Heritage Medical Research Centre, University of Alberta, Edmonton, Alberta, Canada
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