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Dik B, Parlak TM, Ates MB, Tufan O. Exploring the combined therapeutic efficacy of bexarotene and icariin in type 2 diabetic rats. J Pharm Pharmacol 2024:rgae100. [PMID: 39024515 DOI: 10.1093/jpp/rgae100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 07/03/2024] [Indexed: 07/20/2024]
Abstract
OBJECTIVES The aim of this study was to determine the single and combined antidiabetic activity and side effects of the retinoid X receptor agonist bexarotene and the thioredoxin-interacting protein inhibitor and peroxisome proliferator-activated receptor γ and AMP-activated protein kinase activator icariin. METHODS The rats were grouped as healthy (control), diabetes, diabetes + bexarotene (20 mg/kg), diabetes + icariin (60 mg/kg), diabetes + bexarotene (10 mg/kg) + icariin (30 mg/kg) low-dose combination and diabetes + bexarotene (20 mg/kg) + icariin (60 mg/kg) high-dose combination groups. KEY FINDINGS Icariin treatment led to a significant reduction in glucose levels compared with the diabetes control group, a remarkable outcome observed 45 days after the initial application. HbA1c levels of the icariin and low-dose combination treatment groups were significantly lower than in the diabetes group. Notably, icariin treatment also significantly elevated HOMA-β levels, which is indicative of improved β-cell function. Icariin significantly decreased glucose levels at 30 and 120 min in the oral glucose tolerance test. Moreover, it ameliorated hepatocyte degeneration, hepatic cord dissociation, congestion, mononuclear cell infiltration in the liver, and degeneration in the pancreas. CONCLUSIONS Icariin treatment exhibited robust antidiabetic effects with fewer side effects than other treatment options in this study. In future studies, long-term and varying doses of icariin will contribute to the development of novel antidiabetic drugs.
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Affiliation(s)
- Burak Dik
- Department of Pharmacology and Toxicology, Selcuk University, Konya, 42130, Türkiye
| | - Tugba Melike Parlak
- Department of Pharmacology and Toxicology, Selcuk University, Konya, 42130, Türkiye
| | | | - Oznur Tufan
- Department of Pharmacology and Toxicology, Selcuk University, Konya, 42130, Türkiye
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2
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Wiszpolska M, Lepiarczyk E, Maździarz MA, Paukszto Ł, Makowczenko KG, Lipka A, Łopieńska-Biernat E, Makowska K, Gonkowski S, Correia-de-Sá P, Majewska M. The Carcinogenic Potential of Bisphenol A in the Liver Based on Transcriptomic Studies. Cancers (Basel) 2023; 15:5014. [PMID: 37894381 PMCID: PMC10605469 DOI: 10.3390/cancers15205014] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 10/10/2023] [Accepted: 10/13/2023] [Indexed: 10/29/2023] Open
Abstract
Bisphenol A (BPA) is an environmental toxin widely used in the production of polycarbonate plastics. A correlation exists between BPA tissue contamination and the occurrence of pathological conditions, including cancer. First-passage detoxification of high BPA amounts in the liver promotes hepatotoxicity and morphological alterations of this organ, but there is a lack of knowledge about the molecular mechanisms underlying these phenomena. This prompted us to investigate changes in the liver transcriptomics of 3-month-old female mice exposed to BPA (50 mg/kg) in drinking water for 3 months. Five female mice served as controls. The animals were euthanized, the livers were collected, and RNA was extracted to perform RNA-seq analysis. The multistep transcriptomic bioinformatics revealed 120 differentially expressed genes (DEGs) in the BPA-exposed samples. Gene Ontology (GO) annotations indicated that DEGs have been assigned to many biological processes, including "macromolecule modification" and "protein metabolic process". Several of the revealed DEGs have been linked to the pathogenesis of severe metabolic liver disorders and malignant tumors, in particular hepatocellular carcinoma. Data from this study suggest that BPA has a significant impact on gene expression in the liver, which is predictive of the carcinogenic potential of this compound in this organ.
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Affiliation(s)
- Marta Wiszpolska
- Department of Human Physiology and Pathophysiology, School of Medicine, University of Warmia and Mazury in Olsztyn, 10-082 Olsztyn, Poland
| | - Ewa Lepiarczyk
- Department of Human Physiology and Pathophysiology, School of Medicine, University of Warmia and Mazury in Olsztyn, 10-082 Olsztyn, Poland
| | - Mateusz A Maździarz
- Department of Botany and Nature Protection, Faculty of Biology and Biotechnology, University of Warmia and Mazury in Olsztyn, 10-727 Olsztyn, Poland
| | - Łukasz Paukszto
- Department of Botany and Nature Protection, Faculty of Biology and Biotechnology, University of Warmia and Mazury in Olsztyn, 10-727 Olsztyn, Poland
| | - Karol G Makowczenko
- Department of Reproductive Immunology and Pathology, Institute of Animal Reproduction and Food Research of PAS, 10-748 Olsztyn, Poland
| | - Aleksandra Lipka
- Institute of Oral Biology, Faculty of Dentistry, University of Oslo, 0372 Oslo, Norway
| | - Elżbieta Łopieńska-Biernat
- Department of Biochemistry, Faculty of Biology and Biotechnology, University of Warmia and Mazury in Olsztyn, 10-719 Olsztyn, Poland
| | - Krystyna Makowska
- Department of Clinical Diagnostics, Faculty of Veterinary Medicine, University of Warmia and Mazury in Olsztyn, 10-957 Olsztyn, Poland
| | - Sławomir Gonkowski
- Department of Clinical Physiology, Faculty of Veterinary Medicine, University of Warmia and Mazury in Olsztyn, 10-957 Olsztyn, Poland
| | - Paulo Correia-de-Sá
- Laboratório de Farmacologia e Neurobiologia, Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, 4050-313 Porto, Portugal
| | - Marta Majewska
- Department of Human Physiology and Pathophysiology, School of Medicine, University of Warmia and Mazury in Olsztyn, 10-082 Olsztyn, Poland
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Zhang HF, Liu HM, Xiang JY, Zhou XC, Wang D, Chen RY, Tan WL, Liang LQ, Liu LL, Shi MJ, Zhang F, Xiao Y, Zhou YX, Zhang T, Tang L, Guo B, Wang YY. Alpha lipoamide inhibits diabetic kidney fibrosis via improving mitochondrial function and regulating RXRα expression and activation. Acta Pharmacol Sin 2023; 44:1051-1065. [PMID: 36347997 PMCID: PMC10104876 DOI: 10.1038/s41401-022-00997-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 09/06/2022] [Accepted: 09/06/2022] [Indexed: 11/10/2022] Open
Abstract
Previous studies have shown mitochondrial dysfunction in various acute kidney injuries and chronic kidney diseases. Lipoic acid exerts potent effects on oxidant stress and modulation of mitochondrial function in damaged organ. In this study we investigated whether alpha lipoamide (ALM), a derivative of lipoic acid, exerted a renal protective effect in a type 2 diabetes mellitus mouse model. 9-week-old db/db mice were treated with ALM (50 mg·kg-1·d-1, i.g) for 8 weeks. We showed that ALM administration did not affect blood glucose levels in db/db mice, but restored renal function and significantly improved fibrosis of kidneys. We demonstrated that ALM administration significantly ameliorated mitochondrial dysfunction and tubulointerstitial fibrotic lesions, along with increased expression of CDX2 and CFTR and decreased expression of β-catenin and Snail in kidneys of db/db mice. Similar protective effects were observed in rat renal tubular epithelial cell line NRK-52E cultured in high-glucose medium following treatment with ALM (200 μM). The protective mechanisms of ALM in diabetic kidney disease (DKD) were further explored: Autodock Vina software predicted that ALM could activate RXRα protein by forming stable hydrogen bonds. PROMO Database predicted that RXRα could bind the promoter sequences of CDX2 gene. Knockdown of RXRα expression in NRK-52E cells under normal glucose condition suppressed CDX2 expression and promoted phenotypic changes in renal tubular epithelial cells. However, RXRα overexpression increased CDX2 expression which in turn inhibited high glucose-mediated renal tubular epithelial cell injury. Therefore, we reveal the protective effect of ALM on DKD and its possible potential targets: ALM ameliorates mitochondrial dysfunction and regulates the CDX2/CFTR/β-catenin signaling axis through upregulation and activation of RXRα. Schematic figure illustrating that ALM alleviates diabetic kidney disease by improving mitochondrial function and upregulation and activation of RXRα, which in turn upregulated CDX2 to exert an inhibitory effect on β-catenin activation and nuclear translocation. RTEC renal tubular epithelial cell. ROS Reactive oxygen species. RXRα Retinoid X receptor-α. Mfn1 Mitofusin 1. Drp1 dynamic-related protein 1. MDA malondialdehyde. 4-HNE 4-hydroxynonenal. T-SOD Total-superoxide dismutase. CDX2 Caudal-type homeobox transcription factor 2. CFTR Cystic fibrosis transmembrane conductance regulator. EMT epithelial mesenchymal transition. α-SMA Alpha-smooth muscle actin. ECM extracellular matrix. DKD diabetic kidney disease. Schematic figure was drawn by Figdraw ( www.figdraw.com ).
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Affiliation(s)
- Hui-Fang Zhang
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang, 550025, China
- International Scientific and Technological Cooperation Base of Pathogenesis and Drug Research on Common Major Diseases, Guizhou Medical University, Guiyang, 550025, China
- Department of Pathophysiology, Guizhou Medical University, Guiyang, 550025, China
| | - Hui-Ming Liu
- Guizhou Provincial Key Laboratory of Pathogenesis and Drug Research on Common Chronic Diseases, Guizhou Medical University, Guiyang, 550025, China
- Department of Pathology, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Jia-Yi Xiang
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang, 550025, China
- International Scientific and Technological Cooperation Base of Pathogenesis and Drug Research on Common Major Diseases, Guizhou Medical University, Guiyang, 550025, China
- Department of Pathophysiology, Guizhou Medical University, Guiyang, 550025, China
| | - Xing-Cheng Zhou
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang, 550025, China
- International Scientific and Technological Cooperation Base of Pathogenesis and Drug Research on Common Major Diseases, Guizhou Medical University, Guiyang, 550025, China
- Department of Pathophysiology, Guizhou Medical University, Guiyang, 550025, China
| | - Dan Wang
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang, 550025, China
- International Scientific and Technological Cooperation Base of Pathogenesis and Drug Research on Common Major Diseases, Guizhou Medical University, Guiyang, 550025, China
- Department of Pathophysiology, Guizhou Medical University, Guiyang, 550025, China
| | - Rong-Yu Chen
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang, 550025, China
- International Scientific and Technological Cooperation Base of Pathogenesis and Drug Research on Common Major Diseases, Guizhou Medical University, Guiyang, 550025, China
- Department of Pathophysiology, Guizhou Medical University, Guiyang, 550025, China
| | - Wan-Lin Tan
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang, 550025, China
- International Scientific and Technological Cooperation Base of Pathogenesis and Drug Research on Common Major Diseases, Guizhou Medical University, Guiyang, 550025, China
| | - Lu-Qun Liang
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang, 550025, China
- International Scientific and Technological Cooperation Base of Pathogenesis and Drug Research on Common Major Diseases, Guizhou Medical University, Guiyang, 550025, China
- Department of Pathophysiology, Guizhou Medical University, Guiyang, 550025, China
| | - Ling-Ling Liu
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang, 550025, China
- International Scientific and Technological Cooperation Base of Pathogenesis and Drug Research on Common Major Diseases, Guizhou Medical University, Guiyang, 550025, China
- Department of Pathophysiology, Guizhou Medical University, Guiyang, 550025, China
| | - Ming-Jun Shi
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang, 550025, China
- International Scientific and Technological Cooperation Base of Pathogenesis and Drug Research on Common Major Diseases, Guizhou Medical University, Guiyang, 550025, China
- Department of Pathophysiology, Guizhou Medical University, Guiyang, 550025, China
| | - Fan Zhang
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang, 550025, China
- International Scientific and Technological Cooperation Base of Pathogenesis and Drug Research on Common Major Diseases, Guizhou Medical University, Guiyang, 550025, China
- Department of Pathophysiology, Guizhou Medical University, Guiyang, 550025, China
| | - Ying Xiao
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang, 550025, China
- International Scientific and Technological Cooperation Base of Pathogenesis and Drug Research on Common Major Diseases, Guizhou Medical University, Guiyang, 550025, China
- Department of Pathophysiology, Guizhou Medical University, Guiyang, 550025, China
| | - Yu-Xia Zhou
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang, 550025, China
- International Scientific and Technological Cooperation Base of Pathogenesis and Drug Research on Common Major Diseases, Guizhou Medical University, Guiyang, 550025, China
- Department of Pathophysiology, Guizhou Medical University, Guiyang, 550025, China
| | - Tian Zhang
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang, 550025, China
- International Scientific and Technological Cooperation Base of Pathogenesis and Drug Research on Common Major Diseases, Guizhou Medical University, Guiyang, 550025, China
- Department of Pathophysiology, Guizhou Medical University, Guiyang, 550025, China
| | - Lei Tang
- Guizhou Provincial Key Laboratory of Pathogenesis and Drug Research on Common Chronic Diseases, Guizhou Medical University, Guiyang, 550025, China.
- Guizhou Provincial Engineering Technology Research Center for Chemical Drug R&D, Guizhou Medical University, Guiyang, 550025, China.
| | - Bing Guo
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang, 550025, China.
- International Scientific and Technological Cooperation Base of Pathogenesis and Drug Research on Common Major Diseases, Guizhou Medical University, Guiyang, 550025, China.
- Department of Pathophysiology, Guizhou Medical University, Guiyang, 550025, China.
| | - Yuan-Yuan Wang
- International Scientific and Technological Cooperation Base of Pathogenesis and Drug Research on Common Major Diseases, Guizhou Medical University, Guiyang, 550025, China.
- Department of Pathophysiology, Guizhou Medical University, Guiyang, 550025, China.
- Guizhou Provincial Key Laboratory of Pathogenesis and Drug Research on Common Chronic Diseases, Guizhou Medical University, Guiyang, 550025, China.
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4
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Gao S, Zhang X, Xu H, Miao D, Qian J, Wu Z, Shi W. Promoting the hippocampal PPARα expression participates in the antidepressant mechanism of reboxetine, a selective norepinephrine reuptake inhibitor. Behav Brain Res 2022; 416:113535. [PMID: 34416301 DOI: 10.1016/j.bbr.2021.113535] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Revised: 07/11/2021] [Accepted: 08/13/2021] [Indexed: 12/18/2022]
Abstract
Reboxetine, the first selective norepinephrine (NA) reuptake inhibitor used in the treatment of depression, mainly acts by binding to the NA transporter and blocking reuptake of extracellular NA. Recently, some other pharmacological targets beyond the NA transporter are being demonstrated for reboxetine. Peroxisome proliferator activated receptor α (PPARα) is a member of the nuclear hormone receptor family of ligand-dependent transcription factors. Previous reports have demonstrated the role of hippocampal PPARα in the pathophysiology of depression. Here we assume that hippocampal PPARα may participate in the antidepressant mechanism of reboxetine. Therefore, the chronic social defeat stress (CSDS) model of depression, various behavioral tests, the western blotting and adenovirus associated virus (AAV)-mediated genetic knockdown methods were used together in the present study. Our results showed that repeated reboxetine treatment markedly restored the decreasing effects of CSDS on the expression of hippocampal PPARα, brain-derived neurotrophic factor (BDNF) and phosphorylated cAMP response element binding protein (pCREB). Pharmacological blockade of PPARα notably prevented the antidepressant-like effects of reboxetine in the CSDS model. Furthermore, genetic knockdown of hippocampal PPARα also fully abolished the antidepressant-like effects of reboxetine in the CSDS model. Taken together, promoting the hippocampal PPARα expression participates in the antidepressant mechanism of reboxetine.
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Affiliation(s)
- Shangyan Gao
- Department of Neurology, The Affiliated Nantong Hospital of Shanghai University (The Sixth People's Hospital of Nantong), Nantong, 226011, Jiangsu, China
| | - Xueling Zhang
- Department of Neurology, The Affiliated Suqian Hospital of Xuzhou Medical University, Suqian, 223800, Jiangsu, China
| | - Hui Xu
- Department of Neurosurgery, The Affiliated Nantong Hospital of Shanghai University (The Sixth People's Hospital of Nantong), Nantong, 226011, Jiangsu, China
| | - Dongjin Miao
- Department of Neurology, The Affiliated Nantong Hospital of Shanghai University (The Sixth People's Hospital of Nantong), Nantong, 226011, Jiangsu, China
| | - Jiaoni Qian
- Department of Neurology, The Affiliated Nantong Hospital of Shanghai University (The Sixth People's Hospital of Nantong), Nantong, 226011, Jiangsu, China
| | - Zhonghua Wu
- Department of Neurosurgery, The Affiliated Nantong Hospital of Shanghai University (The Sixth People's Hospital of Nantong), Nantong, 226011, Jiangsu, China.
| | - Weihua Shi
- Department of Traditional Chinese Medicine, The Affiliated Hospital of Nantong University, No. 20 Xisi Road, Nantong, 226001, Jiangsu, China.
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5
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Li D, Wu L, Knox B, Chen S, Tolleson WH, Liu F, Yu D, Guo L, Tong W, Ning B. Long noncoding RNA LINC00844-mediated molecular network regulates expression of drug metabolizing enzymes and nuclear receptors in human liver cells. Arch Toxicol 2020; 94:1637-1653. [PMID: 32222775 DOI: 10.1007/s00204-020-02706-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 03/09/2020] [Indexed: 12/21/2022]
Abstract
Noncoding RNAs, such as long noncoding RNAs (lncRNAs) and microRNAs (miRNAs), regulate gene expression in many physiological and pathological processes, including drug metabolism. Drug metabolizing enzymes (DMEs) are critical components in drug-induced liver toxicity. In this study, we used human hepatic HepaRG cells treated with 5 or 10 mM acetaminophen (APAP) as a model system and identified LINC00844 as a toxicity-responsive lncRNA. We analyzed the expression profiles of LINC00844 in different human tissues. In addition, we examined the correlations between the levels of LINC00844 and those of key DMEs and nuclear receptors (NRs) for APAP metabolism in humans. Our results showed that lncRNA LINC00844 is enriched in the liver and its expression correlates positively with mRNA levels of CYP3A4, CYP2E1, SULT2A1, pregnane X receptor (PXR), and hepatocyte nuclear factor (HNF) 4α. We demonstrated that LINC00844 regulates the expression of these five genes in HepaRG cells using gain- and loss-of-function assays. Further, we discovered that LINC00844 is localized predominantly in the cytoplasm and acts as an hsa-miR-486-5p sponge, via direct binding, to protect SULT2A1 from miRNA-mediated gene silencing. Our data also demonstrated a functional interaction between LINC00844 and hsa-miR-486-5p in regulating DME and NR expression in HepaRG cells and primary human hepatocytes. We depicted a LINC00844-mediated regulatory network that involves miRNA and NRs and influences DME expression in response to APAP toxicity.
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Affiliation(s)
- Dongying Li
- National Center for Toxicological Research (NCTR), U.S. Food and Drug Administration (FDA), 3900 NCTR Road, HFT100, Jefferson, AR, 72079, USA
| | - Leihong Wu
- National Center for Toxicological Research (NCTR), U.S. Food and Drug Administration (FDA), 3900 NCTR Road, HFT100, Jefferson, AR, 72079, USA
| | - Bridgett Knox
- National Center for Toxicological Research (NCTR), U.S. Food and Drug Administration (FDA), 3900 NCTR Road, HFT100, Jefferson, AR, 72079, USA
| | - Si Chen
- National Center for Toxicological Research (NCTR), U.S. Food and Drug Administration (FDA), 3900 NCTR Road, HFT100, Jefferson, AR, 72079, USA
| | - William H Tolleson
- National Center for Toxicological Research (NCTR), U.S. Food and Drug Administration (FDA), 3900 NCTR Road, HFT100, Jefferson, AR, 72079, USA
| | - Fang Liu
- National Center for Toxicological Research (NCTR), U.S. Food and Drug Administration (FDA), 3900 NCTR Road, HFT100, Jefferson, AR, 72079, USA
| | - Dianke Yu
- School of Public Health, Qingdao University, Qingdao, China
| | - Lei Guo
- National Center for Toxicological Research (NCTR), U.S. Food and Drug Administration (FDA), 3900 NCTR Road, HFT100, Jefferson, AR, 72079, USA
| | - Weida Tong
- National Center for Toxicological Research (NCTR), U.S. Food and Drug Administration (FDA), 3900 NCTR Road, HFT100, Jefferson, AR, 72079, USA
| | - Baitang Ning
- National Center for Toxicological Research (NCTR), U.S. Food and Drug Administration (FDA), 3900 NCTR Road, HFT100, Jefferson, AR, 72079, USA.
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Ren W, Badgery W, Ding Y, Guo H, Gao Y, Zhang J. Hepatic transcriptome profile of sheep (Ovis aries) in response to overgrazing: novel genes and pathways revealed. BMC Genet 2019; 20:54. [PMID: 31272371 PMCID: PMC6610972 DOI: 10.1186/s12863-019-0760-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 06/26/2019] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Overgrazing is a major factor that causes steppe degradation in Inner Mongolian, resulting in extensive ecosystem damage. Scarcity of grass means sheep are smaller and therefore mutton and cashmere production is greatly reduced, which has resulted in massive annual economic losses. Liver is the primary metabolic organ in mammals. It is also the key source of energy supply and detoxification of metabolites in animals, has a close relationship with animal growth. However, investigations on the responses of sheep induced by consequence of overgrazing, particularly those relating to liver-related molecular mechanisms and related metabolic pathways, remain elusive. RESULTS The body weight daily gain of sheep, immune organ indices (liver and spleen), and serum parameters related to immune response, protein synthesis and energy supply (IgG, albumin, glucose and non-esterified fatty acid) were significantly lower in the overgrazing group. Other serum parameters including alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, total bilirubin, blood urea nitrogen and interleukin-6 were significantly higher in the overgrazing group. For the RNA-Seq results, we identified approximately 50 differentially expressed genes, of which half of were up-regulated and the other half were down-regulated (overgrazing group versus light grazing group). Bioinformatics analysis identified two enriched KEGG pathways including peroxisome proliferator-activated receptor (PPAR) signaling pathway (related to lipolysis) and ECM-receptor interaction (related to liver injury and apoptosis). Additionally, several of the down-regulated genes were related to detoxification and immune response. CONCLUSIONS Overall, based on the high-throughput RNA sequencing profile integrated with the results of serum biochemical analyses, consequences of lower forage availability and quality under overgrazing condition induced altered expression levels of genes participating in energy metabolism (particularly lipid metabolism) and detoxification and immune responses, causing lipolysis and impaired health status, which might be key reasons for the reduced growth performance of sheep. This investigation provides a novel foundation for the development of sheep hepatic gene interactive networks that are a response to the degraded forage availability under overgrazing condition.
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Affiliation(s)
- Weibo Ren
- Key Laboratory of Forage Grass, Ministry of Agriculture, Institute of Grassland Research, Chinese Academy of Agricultural Sciences, Hohhot, 010010, Inner Mongolia, China
| | - Warwick Badgery
- NSW Department of Primary Industries, Orange Agricultural Institute, Orange, NSW, 2800, Australia
| | - Yong Ding
- Key Laboratory of Forage Grass, Ministry of Agriculture, Institute of Grassland Research, Chinese Academy of Agricultural Sciences, Hohhot, 010010, Inner Mongolia, China
| | - Huiqin Guo
- College of Life Sciences, Inner Mongolia Agricultural University, Hohhot, 010019, Inner Mongolia, China
| | - Yang Gao
- College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130018, Jilin, China
| | - Jize Zhang
- Key Laboratory of Forage Grass, Ministry of Agriculture, Institute of Grassland Research, Chinese Academy of Agricultural Sciences, Hohhot, 010010, Inner Mongolia, China.
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7
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Pan M, Jiao S, Reinach PS, Yan J, Yang Y, Li Q, Srinivasalu N, Qu J, Zhou X. Opposing Effects of PPARα Agonism and Antagonism on Refractive Development and Form Deprivation Myopia in Guinea Pigs. Invest Ophthalmol Vis Sci 2019; 59:5803-5815. [PMID: 30521668 DOI: 10.1167/iovs.17-22297] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To determine if drug-induced peroxisome proliferator-activated receptor α (PPARα) signal pathway modulation affects refractive development and myopia in guinea pigs. Methods Pigmented guinea pigs were randomly divided into normal vision (unoccluded) and form deprivation myopia (FDM) groups. Each group received daily peribulbar injections of either a vehicle or (1) PPARα agonist, GW7647, clofibrate, or bezafibrate or (2) PPARα antagonist, GW6471, for 4 weeks. Baseline and posttreatment refraction and ocular biometric parameters were measured. Immunofluorescent staining of PPARα and two of its downstream readouts, cytosolic malic enzyme 1 (ME1) and apolipoproteinA II (apoA-II), was undertaken in selected scleral sections. Western blot analysis determined collagen type I expression levels. Results GW6471 induced a myopic shift in unoccluded eyes, but had no effect on form-deprived eyes. Conversely, GW7647 inhibited FDM progression without altering unoccluded eyes. Bezafibrate and clofibrate had effects on refraction similar to those of GW7647 in unoccluded and form-deprived eyes. GW6471 downregulated collagen type I expression in unoccluded eyes whereas bezafibrate inhibited collagen type I decreases in form-deprived eyes. GW6471 also reduced the density of ME1- and apoA-II-stained cells in unoccluded eyes whereas bezafibrate increased apoA-II-positive cell numbers in form-deprived eyes. Conclusions As GW7647 and GW6471 had opposing effects on myopia development, PPARα signaling modulation may be involved in this condition in guinea pigs. Fibrates are potential candidates for treating myopia since they reduced both FDM and the associated axial elongation. Bezafibrate also inhibited form deprivation-induced decreases in scleral collagen type I expression and the density of apoA-II expressing cells.
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Affiliation(s)
- Miaozhen Pan
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.,State Key Laboratory of Optometry, Ophthalmology, and Vision Science, Affiliated Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, People's Republic of China
| | - Shiming Jiao
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.,State Key Laboratory of Optometry, Ophthalmology, and Vision Science, Affiliated Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, People's Republic of China
| | - Peter S Reinach
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.,State Key Laboratory of Optometry, Ophthalmology, and Vision Science, Affiliated Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, People's Republic of China
| | - Jiaofeng Yan
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.,State Key Laboratory of Optometry, Ophthalmology, and Vision Science, Affiliated Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, People's Republic of China
| | - Yanan Yang
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.,State Key Laboratory of Optometry, Ophthalmology, and Vision Science, Affiliated Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, People's Republic of China
| | - Qihang Li
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.,State Key Laboratory of Optometry, Ophthalmology, and Vision Science, Affiliated Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, People's Republic of China
| | - Nethrajeith Srinivasalu
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.,State Key Laboratory of Optometry, Ophthalmology, and Vision Science, Affiliated Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, People's Republic of China
| | - Jia Qu
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.,State Key Laboratory of Optometry, Ophthalmology, and Vision Science, Affiliated Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, People's Republic of China
| | - Xiangtian Zhou
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.,State Key Laboratory of Optometry, Ophthalmology, and Vision Science, Affiliated Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, People's Republic of China
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8
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KLF15 and PPARα Cooperate to Regulate Cardiomyocyte Lipid Gene Expression and Oxidation. PPAR Res 2015; 2015:201625. [PMID: 25815008 PMCID: PMC4357137 DOI: 10.1155/2015/201625] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 02/19/2015] [Indexed: 12/13/2022] Open
Abstract
The metabolic myocardium is an omnivore and utilizes various carbon substrates to meet its energetic demand. While the adult heart preferentially consumes fatty acids (FAs) over carbohydrates, myocardial fuel plasticity is essential for organismal survival. This metabolic plasticity governing fuel utilization is under robust transcriptional control and studies over the past decade have illuminated members of the nuclear receptor family of factors (e.g., PPARα) as important regulators of myocardial lipid metabolism. However, given the complexity of myocardial metabolism in health and disease, it is likely that other molecular pathways are likely operative and elucidation of such pathways may provide the foundation for novel therapeutic approaches. We previously demonstrated that Kruppel-like factor 15 (KLF15) is an independent regulator of cardiac lipid metabolism thus raising the possibility that KLF15 and PPARα operate in a coordinated fashion to regulate myocardial gene expression requisite for lipid oxidation. In the current study, we show that KLF15 binds to, cooperates with, and is required for the induction of canonical PPARα-mediated gene expression and lipid oxidation in cardiomyocytes. As such, this study establishes a molecular module involving KLF15 and PPARα and provides fundamental insights into the molecular regulation of cardiac lipid metabolism.
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9
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Tang XH, Osei-Sarfo K, Urvalek AM, Zhang T, Scognamiglio T, Gudas LJ. Combination of bexarotene and the retinoid CD1530 reduces murine oral-cavity carcinogenesis induced by the carcinogen 4-nitroquinoline 1-oxide. Proc Natl Acad Sci U S A 2014; 111:8907-12. [PMID: 24927566 PMCID: PMC4066471 DOI: 10.1073/pnas.1404828111] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
We investigated the effects of bexarotene (a retinoid X receptor agonist), CD1530 (a retinoic acid receptor γ selective agonist), and the combination of these two drugs for the prevention of oral carcinogenesis induced by the carcinogen 4-nitroquinoline 1-oxide (4-NQO) in a mouse model of human oral-cavity and esophageal squamous-cell carcinoma previously generated in our laboratory. We observed decreased numbers of neoplastic tongue lesions and reduced lesion severity in the 4-NQO plus CD1530 (4N+C) and 4-NQO plus bexarotene plus CD1530 (4N+B+C) groups compared with the 4-NQO group. RNA-Seq analyses showed increases in transcripts in cell proliferation/cell cycle progression pathways in the 4-NQO vs. the untreated group. In addition, β-catenin and matrix metallopeptidase 9 (MMP9) protein levels and reactive oxygen species (ROS), as assessed by 4-hydroxynonenal (4-HNE) staining, were elevated in tongue tissues 17 wk after the termination of the 4-NQO treatment. The 4N+B, 4N+C, and 4N+B+C groups showed dramatically lower levels of β-catenin, MMP9, and 4-HNE staining compared with the 4-NQO group. The major reduction in 4-HNE staining in the retinoid treatment groups suggests a novel mechanism of action, reduction of ROS, by which bexarotene and CD1530 inhibit carcinogenesis.
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Affiliation(s)
| | | | | | - Tuo Zhang
- Genomics Resources Core Facility, and
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10
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Integrated physiology and systems biology of PPARα. Mol Metab 2014; 3:354-71. [PMID: 24944896 PMCID: PMC4060217 DOI: 10.1016/j.molmet.2014.02.002] [Citation(s) in RCA: 411] [Impact Index Per Article: 41.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 02/20/2014] [Accepted: 02/21/2014] [Indexed: 12/23/2022] Open
Abstract
The Peroxisome Proliferator Activated Receptor alpha (PPARα) is a transcription factor that plays a major role in metabolic regulation. This review addresses the functional role of PPARα in intermediary metabolism and provides a detailed overview of metabolic genes targeted by PPARα, with a focus on liver. A distinction is made between the impact of PPARα on metabolism upon physiological, pharmacological, and nutritional activation. Low and high throughput gene expression analyses have allowed the creation of a comprehensive map illustrating the role of PPARα as master regulator of lipid metabolism via regulation of numerous genes. The map puts PPARα at the center of a regulatory hub impacting fatty acid uptake, fatty acid activation, intracellular fatty acid binding, mitochondrial and peroxisomal fatty acid oxidation, ketogenesis, triglyceride turnover, lipid droplet biology, gluconeogenesis, and bile synthesis/secretion. In addition, PPARα governs the expression of several secreted proteins that exert local and endocrine functions.
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11
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Modulation of RXR function through ligand design. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:57-69. [PMID: 21515403 DOI: 10.1016/j.bbalip.2011.04.003] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Revised: 04/06/2011] [Accepted: 04/07/2011] [Indexed: 12/22/2022]
Abstract
As the promiscuous partner of heterodimeric associations, retinoid X receptors (RXRs) play a key role within the Nuclear Receptor (NR) superfamily. Some of the heterodimers (PPAR/RXR, LXR/RXR, FXR/RXR) are "permissive" as they become transcriptionally active in the sole presence of either an RXR-selective ligand ("rexinoid") or a NR partner ligand. In contrast, "non-permissive" heterodimers (including RAR/RXR, VDR/RXR and TR/RXR) are unresponsive to rexinoids alone but these agonists superactivate transcription by synergizing with partner agonists. Despite their promiscuity in heterodimer formation and activation of multiple pathways, RXR is a target for drug discovery. Indeed, a rexinoid is used in the clinic for the treatment of cutaneous T-cell lymphoma. In addition to cancer RXR modulators hold therapeutical potential for the treatment of metabolic diseases. The modulation potential of the rexinoid (as agonist or antagonist ligand) is dictated by the precise conformation of the ligand-receptor complexes and the nature and extent of their interaction with co-regulators, which determine the specific physiological responses through transcription modulation of cognate gene networks. Notwithstanding the advances in this field, it is not yet possible to predict the correlation between ligand structure and physiological response. We will focus on this review on the modulation of PPARγ/RXR and LXR/RXR heterodimer activities by rexinoids. The genetic and pharmacological data from animal models of insulin resistance, diabetes and obesity demonstrate that RXR agonists and antagonists have promise as anti-obesity agents. However, the treatment with rexinoids raises triglycerides levels, suppresses the thyroid hormone axis, and induces hepatomegaly, which has complicated the development of these compounds as therapeutic agents for the treatment of type 2 diabetes and insulin resistance. The discovery of PPARγ/RXR and LXR/RXR heterodimer-selective rexinoids, which act differently than PPARγ or LXR agonists, might overcome some of these limitations.
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12
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Effects of dietary lutein and PUFA on PPAR and RXR isomer expression in chickens during an inflammatory response. Comp Biochem Physiol A Mol Integr Physiol 2010; 157:198-203. [PMID: 20601055 DOI: 10.1016/j.cbpa.2010.06.172] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 06/10/2010] [Accepted: 06/11/2010] [Indexed: 12/17/2022]
Abstract
This study investigated the effects of dietary lutein and polyunsaturated fatty acids (PUFA) on the total lutein and lipid levels, the peroxisome proliferators activated receptors (PPAR) alpha and gamma, retinoic acid X receptor (RXR) alpha and gamma and IL-1 mRNA levels in chicken (Gallus gallus) liver and spleen. In experiment I, chickens were fed either 0, 25 or 50mg lutein in a diet with 3% PUFA fat. In experiment II, chickens were fed either 3 or 6% PUFA fat with 25mg lutein. At 23d of age, chickens were injected with LPS. LPS injection decreased the lutein content and increased the fat content in the liver and spleen in both experiments. Increasing dietary PUFA fat to 6% ameliorated the LPS-induced lutein depletion in experiment II. LPS injection increased IL-1 and decreased splenic PPARalpha, PPARgamma, RXRalpha mRNA in experiment I and II. The LPS-induced PPARalpha and RXRalpha downregulation were partially reversed by increasing the dietary lutein content to 50mg/kg feed in experiment I and by increasing the dietary PUFA fat content to 6% in experiment II. Increasing dietary lutein content to 50mg/kg feed increased PPARgamma mRNA amount only in the LPS untreated groups in experiment I. Increasing dietary PUFA fat or LPS injection in the 6% PUFA fat group upregulated PPARgamma mRNA in experiment II. Increasing dietary PUFA fat to 6% blunted the increase in IL-1 mRNA due to LPS. It is concluded that dietary lutein and PUFA fat were anti-inflammatory due to modification of immune tissue lutein content, PPAR, RXR isomers and IL-1beta mRNA levels in liver and spleen.
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13
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Puthanveetil P, Wang Y, Wang F, Kim MS, Abrahani A, Rodrigues B. The increase in cardiac pyruvate dehydrogenase kinase-4 after short-term dexamethasone is controlled by an Akt-p38-forkhead box other factor-1 signaling axis. Endocrinology 2010; 151:2306-18. [PMID: 20181797 DOI: 10.1210/en.2009-1072] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Glucocorticoids increase pyruvate dehydrogenase kinase-4 (PDK4) mRNA and protein expression, which phosphorylates pyruvate dehydrogenase, thereby preventing the formed pyruvate from undergoing mitochondrial oxidation. This increase in PDK4 expression is mediated by the mandatory presence of Forkhead box other factors (FoxOs) in the nucleus. In the current study, we examined the importance of the nongenomic effects of dexamethasone (Dx) in determining the compartmentalization of FoxO and hence its transcriptional activity. Rat cardiomyocytes exposed to Dx produced a robust decrease in glucose oxidation. Measurement of FoxO compartmentalization demonstrated increase in nuclear but resultant decrease in cytosolic content of FoxO1 with no change in the total content. The increase in nuclear content of FoxO1 correlated to an increase in nuclear phospho-p38 MAPK together with a robust association between this transcription factor and kinase. Dx also promoted nuclear retention of FoxO1 through a decrease in phosphorylation of Akt, an effect mediated by heat shock proteins binding to Akt. Measurement of the nuclear and total expression of sirtuin-1 protein showed no change after Dx. Instead, Dx increased the association of sirtuin-1 with FoxO1, thereby causing a decrease in FoxO acetylation. Manipulation of FoxO1 through agents that interfere with its nuclear shuttling or acetylation were effective in reducing Dx-induced increase in PDK4 protein expression. Our data suggest that FoxO1 has a major PDK4-regulating function. In addition, given the recent suggestions that altering glucose use can set the stage for heart failure, manipulating FoxO could assist in devising new therapeutic strategies to optimize cardiac metabolism and prevent PDK4 induced cardiac complications.
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Affiliation(s)
- Prasanth Puthanveetil
- Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia, Canada
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14
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Lalloyer F, Pedersen TA, Gross B, Lestavel S, Yous S, Vallez E, Gustafsson JA, Mandrup S, Fiévet C, Staels B, Tailleux A. Rexinoid bexarotene modulates triglyceride but not cholesterol metabolism via gene-specific permissivity of the RXR/LXR heterodimer in the liver. Arterioscler Thromb Vasc Biol 2009; 29:1488-95. [PMID: 19592467 DOI: 10.1161/atvbaha.109.189506] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Bexarotene (Targretin) is a clinically used antitumoral agent which exerts its action through binding to and activation of the retinoid-X-receptor (RXR). The most frequent side-effect of bexarotene administration is an increase in plasma triglycerides, an independent risk factor of cardiovascular disease. The molecular mechanism behind this hypertriglyceridemia remains poorly understood. METHODS AND RESULTS Using wild-type and LXR alpha/beta-deficient mice, we show here that bexarotene induces hypertriglyceridemia and activates hepatic LXR-target genes of lipogenesis in an LXR-dependent manner, hence exerting a permissive effect on RXR/LXR heterodimers. Interestingly, RNA analysis and Chromatin Immunoprecipitation assays performed in the liver reveal that the in vivo permissive effect of bexarotene on the RXR/LXR heterodimer is restricted to lipogenic genes without modulation of genes controlling cholesterol homeostasis. CONCLUSIONS These findings demonstrate that the hypertriglyceridemic action of bexarotene occurs via the RXR/LXR heterodimer and show that RXR heterodimers can act with a selective permissivity on target genes of specific metabolic pathways in the liver.
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15
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Isabel Panadero M, González MDC, Herrera E, Bocos C. Modulación del PPARα por agentes farmacológicos y naturales y sus implicaciones metabólicas. CLINICA E INVESTIGACION EN ARTERIOSCLEROSIS 2008. [DOI: 10.1016/s0214-9168(08)75789-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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16
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Qin S, Okawa Y, Atangan LI, Brown G, Chandraratna RA, Zhao Y. Integrities of A/B and C domains of RXR are required for rexinoid-induced caspase activations and apoptosis. J Steroid Biochem Mol Biol 2008; 112:25-31. [PMID: 18761406 DOI: 10.1016/j.jsbmb.2008.08.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Revised: 03/19/2008] [Accepted: 08/05/2008] [Indexed: 11/16/2022]
Abstract
Here we have delineated regions of the retinoid X receptor alpha (RXRalpha) that are required for rexinoid (RXR agonist)-induced growth inhibition and apoptosis. Stable over-expression of RXRalpha in DT40 B lymphoma cells dramatically increased sensitivity to rexinoid-induced growth inhibition. By contrast, DT40 cells that over-expressed RXRalpha with a deletion of either the A/B or DNA binding domain (C domain) were resistant. We confirmed the importance of C domain integrity by point-mutating Cys(135) to Ser (C135S) to disrupt zinc-finger formation. Point mutating RXR Lys(201) to Thr and Arg(202) to Ala (KTRA) impairs RXR homodimer formation and does not affect RXR heterodimerization. When these mutated RXRs were over-expressed in DT40 cells, they failed to increase sensitivity to rexinoid. Over-expression did sensitize to growth inhibition by RAR and PPARgamma agonists. Over-expression of C135S mutated RXRalpha did not sensitize to RAR and PPARgamma agonists. Inhibitors of caspase-3 and/or caspase-9 blocked rexinoid-induced apoptosis, and activations of these caspases correlated with the ability of RXR mutants to induce cell death. These data show that the A/B and C domains of RXR and the ability of RXR to form homodimers are required for rexinoid-driven growth inhibition, caspase activation and subsequent apoptosis.
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Affiliation(s)
- Suofu Qin
- Retinoid Research, Department of Biology and Chemistry, Allergan Inc., Irvine, CA 92612, USA
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17
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Sanderson LM, de Groot PJ, Hooiveld GJEJ, Koppen A, Kalkhoven E, Müller M, Kersten S. Effect of synthetic dietary triglycerides: a novel research paradigm for nutrigenomics. PLoS One 2008; 3:e1681. [PMID: 18301758 PMCID: PMC2244803 DOI: 10.1371/journal.pone.0001681] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2007] [Accepted: 01/24/2008] [Indexed: 11/18/2022] Open
Abstract
Background The effect of dietary fats on human health and disease are likely mediated by changes in gene expression. Several transcription factors have been shown to respond to fatty acids, including SREBP-1c, NF-κB, RXRs, LXRs, FXR, HNF4α, and PPARs. However, it is unclear to what extent these transcription factors play a role in gene regulation by dietary fatty acids in vivo. Methodology/Principal Findings Here, we take advantage of a unique experimental design using synthetic triglycerides composed of one single fatty acid in combination with gene expression profiling to examine the effects of various individual dietary fatty acids on hepatic gene expression in mice. We observed that the number of significantly changed genes and the fold-induction of genes increased with increasing fatty acid chain length and degree of unsaturation. Importantly, almost every single gene regulated by dietary unsaturated fatty acids remained unaltered in mice lacking PPARα. In addition, the majority of genes regulated by unsaturated fatty acids, especially docosahexaenoic acid, were also regulated by the specific PPARα agonist WY14643. Excellent agreement was found between the effects of unsaturated fatty acids on mouse liver versus cultured rat hepatoma cells. Interestingly, using Nuclear Receptor PamChip® Arrays, fatty acid- and WY14643-induced interactions between PPARα and coregulators were found to be highly similar, although several PPARα-coactivator interactions specific for WY14643 were identified. Conclusions/Significance We conclude that the effects of dietary unsaturated fatty acids on hepatic gene expression are almost entirely mediated by PPARα and mimic those of synthetic PPARα agonists in terms of regulation of target genes and molecular mechanism. Use of synthetic dietary triglycerides may provide a novel paradigm for nutrigenomics research.
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Affiliation(s)
- Linda M. Sanderson
- Nutrigenomics Consortium, Top Institute (TI) Food and Nutrition, Wageningen, The Netherlands
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
| | - Philip J. de Groot
- Nutrigenomics Consortium, Top Institute (TI) Food and Nutrition, Wageningen, The Netherlands
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
| | - Guido J. E. J. Hooiveld
- Nutrigenomics Consortium, Top Institute (TI) Food and Nutrition, Wageningen, The Netherlands
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
| | - Arjen Koppen
- Department of Metabolic and Endocrine Diseases, Universitair Medisch Centrum (UMC) Utrecht, Utrecht, The Netherlands
| | - Eric Kalkhoven
- Department of Metabolic and Endocrine Diseases, Universitair Medisch Centrum (UMC) Utrecht, Utrecht, The Netherlands
| | - Michael Müller
- Nutrigenomics Consortium, Top Institute (TI) Food and Nutrition, Wageningen, The Netherlands
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
| | - Sander Kersten
- Nutrigenomics Consortium, Top Institute (TI) Food and Nutrition, Wageningen, The Netherlands
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
- * To whom correspondence should be addressed. E-mail:
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Horn TL, Torres KEO, Naylor JM, Cwik MJ, Detrisac CJ, Kapetanovic IM, Lubet RA, Crowell JA, McCormick DL. Subchronic toxicity and toxicogenomic evaluation of tamoxifen citrate + bexarotene in female rats. Toxicol Sci 2007; 99:612-27. [PMID: 17630414 DOI: 10.1093/toxsci/kfm181] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Tamoxifen (TAM) is a nonsteroidal antiestrogen that prevents estrogen receptor-positive breast cancer in rodents and humans. Bexarotene (BEX), a selective agonist for retinoid X receptors, inhibits mammary carcinogenesis in rodents. The present study was conducted to support the preclinical development of TAM (tamoxifen citrate) + BEX for use in breast cancer chemoprevention, and to investigate the influence of these agents on hepatic gene expression. Female CD rats (20 per group) received daily oral (gavage) exposure to TAM (0 or 60 microg/kg/day) and/or BEX (0, 5, 15, or 45 mg/kg/day) for a minimum of 90 days. BEX induced mild, dose-related anemia and dose-related increases in serum alkaline phosphatase, cholesterol, triglycerides, and calcium levels, and increased platelet counts. TAM had no biologically significant effect on any clinical pathology parameter and did not alter the effects of BEX on these endpoints. Microscopic alterations induced by BEX included epidermal hyperplasia, hyperkeratosis (stomach), and cytoplasmic clearing (liver). Microscopic changes in TAM-treated rats were limited to mucous cell hypertrophy in the cervix and vagina. The toxicity of administration of the combination of TAM + BEX can generally be predicted on the basis of the toxicity of each drug as a single agent. BEX induced dose-related alterations in the expression of several genes involved in steroid, drug, and/or fatty acid metabolism; TAM did not alter these effects of BEX. Differential expression of genes involved in drug and lipid metabolism may underlie the observed effects of BEX on cholesterol and triglyceride levels and its effects on liver histology.
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Affiliation(s)
- Thomas L Horn
- Life Sciences Group, IIT Research Institute, Chicago, Illinois 60616, USA
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19
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Oliveros LB, Domeniconi MA, Vega VA, Gatica LV, Brigada AM, Gimenez MS. Vitamin A deficiency modifies lipid metabolism in rat liver. Br J Nutr 2007; 97:263-72. [PMID: 17298694 DOI: 10.1017/s0007114507182659] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Liver fatty acid metabolism of male rats fed on a vitamin A-deficient diet for 3 months from 21 d of age was evaluated. Vitamin A restriction produced subclinical plasma and negligible liver retinol concentrations, compared with the control group receiving the same diet with 4000 IU vitamin A (8 mg retinol as retinyl palmitate)/kg diet. Vitamin A deficiency induced a hypolipidaemic effect by decreasing serum triacylglycerol, cholesterol and HDL-cholesterol levels. The decrease of liver total phospholipid was associated with low phosphatidylcholine synthesis observed by lower [14C]choline incorporation into phosphatidylcholine, compared with control. Also, liver fatty acid synthesis decreased, as was indicated by activity and mRNA expression of acetyl-CoA carboxylase (ACC), and incorporation of [14C]acetate into saponified lipids. A decrease of the PPARalpha mRNA expression was observed. Liver mitochondria of vitamin A-deficient rats showed a lower total phospholipid concentration coinciding with a decrease of the cardiolipin proportion, without changes in the other phospholipid fractions determined. The mitochondria fatty acid oxidation increased by 30 % of the control value and it was attributed to a high activity and mRNA expression of carnitine palmitoyltransferase-I (CPT-I). An increase in serum beta-hydroxybutyrate levels was observed in vitamin A-deficient rats. Vitamin A deficiency alters the mitochondria lipid composition and also enhances fatty acid oxidation by modifying the production of malonyl-CoA, the endogenous inhibitor of CPT-I, due to decreased activity of liver ACC. The incorporation of vitamin A into the diet of vitamin A-deficient rats reverted all the changes observed.
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Affiliation(s)
- Liliana B Oliveros
- Laboratory of Biological Chemistry, Faculty of Chemistry, Biochemistry and Pharmacy, National University of San Luis, Avenida Ejército de los Andes 954, 5700 San Luis, Argentina
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20
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Arikawa E, Ma RCW, Isshiki K, Luptak I, He Z, Yasuda Y, Maeno Y, Patti ME, Weir GC, Harris RA, Zammit VA, Tian R, King GL. Effects of insulin replacements, inhibitors of angiotensin, and PKCbeta's actions to normalize cardiac gene expression and fuel metabolism in diabetic rats. Diabetes 2007; 56:1410-20. [PMID: 17363743 DOI: 10.2337/db06-0655] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
High-density oligonucleotide arrays were used to compare gene expression of rat hearts from control, untreated diabetic, and diabetic groups treated with islet cell transplantation (ICT), protein kinase C (PKC)beta inhibitor ruboxistaurin, or ACE inhibitor captopril. Among the 376 genes that were differentially expressed between untreated diabetic and control hearts included key metabolic enzymes that account for the decreased glucose and increased free fatty acid utilization in the diabetic heart. ICT or insulin replacements reversed these gene changes with normalization of hyperglycemia, dyslipidemia, and cardiac PKC activation in diabetic rats. Surprisingly, both ruboxistaurin and ACE inhibitors improved the metabolic gene profile (confirmed by real-time RT-PCR and protein analysis) and ameliorated PKC activity in diabetic hearts without altering circulating metabolites. Functional assessments using Langendorff preparations and (13)C nuclear magnetic resonance spectroscopy showed a 36% decrease in glucose utilization and an impairment in diastolic function in diabetic rat hearts, which were normalized by all three treatments. In cardiomyocytes, PKC inhibition attenuated fatty acid-induced increases in the metabolic genes PDK4 and UCP3 and also prevented fatty acid-mediated inhibition of basal and insulin-stimulated glucose oxidation. Thus, PKCbeta or ACE inhibitors may ameliorate cardiac metabolism and function in diabetes partly by normalization of fuel metabolic gene expression directly in the myocardium.
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Affiliation(s)
- Emi Arikawa
- Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA
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Pinaire JA, Reifel-Miller A. Therapeutic potential of retinoid x receptor modulators for the treatment of the metabolic syndrome. PPAR Res 2007; 2007:94156. [PMID: 17497022 PMCID: PMC1852898 DOI: 10.1155/2007/94156] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2006] [Revised: 01/04/2007] [Accepted: 01/04/2007] [Indexed: 01/30/2023] Open
Abstract
The increasing prevalence of obesity is a fundamental contributor
to the growing prevalence of the metabolic syndrome. Rexinoids, a
class of compounds that selectively bind and activate RXR,
are being studied as a potential option for the treatment of
metabolic syndrome. These compounds have glucose-lowering,
insulin-sensitizing, and antiobesity effects in animal models
of insulin resistance and type 2 diabetes. However,
undesirable side effects such as hypertriglyceridemia and
suppression of the thyroid hormone axis also occur.
This review examines and compares the effects of four RXR-selective
ligands: LGD1069, LG100268, AGN194204, and LG101506, a selective
RXR modulator. Similar to selective modulators of other nuclear
receptors such as the estrogen receptor (SERMs), LG101506
binding to RXR selectively maintains the desirable characteristic
effects of rexinoids while minimizing the undesirable effects.
These recent findings suggest that, with continued research efforts,
RXR-specific ligands with improved pharmacological profiles may
eventually be available as additional treatment options for the
current epidemic of obesity, insulin resistance, type 2 diabetes,
and all of the associated metabolic sequelae.
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Affiliation(s)
- Jane A. Pinaire
- Lilly Research Laboratories, Lilly Corporate Center, Indianapolis, IN 46285, USA
- *Jane A. Pinaire:
| | - Anne Reifel-Miller
- Lilly Research Laboratories, Lilly Corporate Center, Indianapolis, IN 46285, USA
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Abstract
Vitamin A signaling occurs through nuclear receptors recognizing diverse forms of retinoic acid (RA). The retinoic acid receptors (RARs) bind all-trans RA and its 9-cis isomer (9-cis RA). They convey most of the activity of RA, particularly during embryogenesis. The second subset of receptors, the rexinoid receptors (RXRs), binds 9-cis RA only. However, RXRs are obligatory DNA-binding partners for a number of nuclear receptors, broadening the spectrum of their biological activity to the corresponding nuclear receptor-signaling pathways. The present chapter more particularly focuses on RXR-containing transcriptional complexes for which RXR is not only a structural component necessary for DNA binding but also acts as a ligand-activated partner. After positioning RXR among the nuclear receptor superfamily in the first part, we will give an overview of three major signaling pathways involved in metabolism, which are sensitive to RXR activation: LXR:RXR, FXR:RXR, and PPAR:RXR. The third and last part is focused on RXR signaling and its potential role in metabolic regulation. Indeed, while the nature of the endogenous ligand for RXR is still in question, as we will discuss herein, a better understanding of RXR activities is necessary to envisage the potential therapeutic applications of synthetic RXR ligands.
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Affiliation(s)
- Béatrice Desvergne
- Center for Integrative Genomics, Building Génopode, University of Lausanne, CH-1015 Lausanne, Switzerland
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23
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Sugden MC, Holness MJ. Mechanisms underlying regulation of the expression and activities of the mammalian pyruvate dehydrogenase kinases. Arch Physiol Biochem 2006; 112:139-49. [PMID: 17132539 DOI: 10.1080/13813450600935263] [Citation(s) in RCA: 191] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The mechanisms that control mammalian pyruvate dehydrogenase complex (PDC) activity include its phosphorylation (inactivation) by a family of pyruvate dehydrogenase kinases (PDKs 1 - 4). Here we review new developments in the regulation of the activities and expression of the PDKs, in particular PDK2 and PDK4, in relation to glucose and lipid homeostasis. This review describes recent advances relating to the acute and long-term modes of regulation of the PDKs, with particular emphasis on the regulatory roles of nuclear receptors including peroxisome proliferator-activated receptor (PPAR) alpha and Liver X receptor (LXR), PPAR gamma coactivator alpha (PGC-1alpha) and insulin, and the impact of changes in PDK activity and expression in glucose and lipid homeostasis. Since PDK4 may assist in lipid clearance when there is an imbalance between lipid delivery and oxidation, it may represent an attractive target for interventions aimed at rectifying abnormal lipid as well as glucose homeostasis in disease states.
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Affiliation(s)
- Mary C Sugden
- Centre for Diabetes and Metabolic Medicine, Institute of Cell and Molecular Science, Bart's and the London, Queen Mary's School of Medicine and Dentistry, London, UK.
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24
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Abstract
Our understanding of metabolism is undergoing a dramatic shift. Indeed, the efforts made towards elucidating the mechanisms controlling the major regulatory pathways are now being rewarded. At the molecular level, the crucial role of transcription factors is particularly well-illustrated by the link between alterations of their functions and the occurrence of major metabolic diseases. In addition, the possibility of manipulating the ligand-dependent activity of some of these transcription factors makes them attractive as therapeutic targets. The aim of this review is to summarize recent knowledge on the transcriptional control of metabolic homeostasis. We first review data on the transcriptional regulation of the intermediary metabolism, i.e., glucose, amino acid, lipid, and cholesterol metabolism. Then, we analyze how transcription factors integrate signals from various pathways to ensure homeostasis. One example of this coordination is the daily adaptation to the circadian fasting and feeding rhythm. This section also discusses the dysregulations causing the metabolic syndrome, which reveals the intricate nature of glucose and lipid metabolism and the role of the transcription factor PPARgamma in orchestrating this association. Finally, we discuss the molecular mechanisms underlying metabolic regulations, which provide new opportunities for treating complex metabolic disorders.
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Affiliation(s)
- Béatrice Desvergne
- Center for Integrative Genomics, National Centre of Competence in Research Frontiers in Genetics, University of Lausanne, Lausanne, Switzerland
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25
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Gong Y, Zhang Z. Alternative signaling pathways: when, where and why? FEBS Lett 2005; 579:5265-74. [PMID: 16194539 DOI: 10.1016/j.febslet.2005.08.062] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2005] [Revised: 08/29/2005] [Accepted: 08/30/2005] [Indexed: 11/24/2022]
Abstract
Alternative cell signal transduction pathways have been demonstrated in some experimental systems. The importance of their existence has not been completely appreciated. In this review we present the cases of alternative pathways resulted from a survey of the available experimental data. The alternative pathways could show different relationships, i.e., synergistic, redundant, additive, opposite and competitive effects. They could have distinct time courses and cell, organ, sex or species specification. Further, they could happen during physiological or pathological situations, and display differentiated sensitivity. These case studies together imply that alternative signal pathways could be involved in the regulation of cell functions at the pathway level. In-depth understanding of the importance of the alternative pathways will rely on building and exploration of mathematical models.
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Affiliation(s)
- Yunchen Gong
- Banting and Best Department of Medical Research, University of Toronto 112 College, Canada.
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26
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Martin PGP, Lasserre F, Calleja C, Van Es A, Roulet A, Concordet D, Cantiello M, Barnouin R, Gauthier B, Pineau T. Transcriptional modulations by RXR agonists are only partially subordinated to PPARalpha signaling and attest additional, organ-specific, molecular cross-talks. Gene Expr 2005; 12:177-92. [PMID: 16128002 PMCID: PMC6009114 DOI: 10.3727/000000005783992098] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Nuclear hormone receptors (NR) are important transcriptional regulators of numerous genes involved in diverse pathophysiological and therapeutic functions. Following ligand activation, class II NR share the ability to heterodimerize with the retinoid X receptor (RXR). It is established that RXR activators, rexinoids, transactivate several peroxisome proliferator-activated receptor alpha (PPARalpha) target genes in a PPARalpha-dependent manner. We hypothesized that, once activated, RXR might signal through quiescent NR other than PPARalpha, in an organ-specific manner. To study this putative phenomenon in vivo, we developed an array of 120 genes relevant to the class II NR field. The genes were selected using both published data and high-density screenings performed on RXR or PPARalpha agonist-treated mice. Wild-type C57BL/6J and PPARalpha-deficient mice were treated with fenofibrate (PPARalpha activator) or LGD1069 (RXR activator). Using our customized array, we studied the hepatic, cardiac, and renal expression of this panel of 120 genes and compared them in both murine genotypes. The results obtained from this study confirmed the ability of an RXR agonist to modulate PPARalpha-restricted target genes in the liver and the kidney. Furthermore, we show that various organ-specific regulations occurring in both genotypes (PPARalpha +/+ or -/-) are highly indicative of the ability of RXR to recruit other class II NR pathways. Further development of this molecular tool may lead to a better understanding of the permissiveness of class II nuclear receptor dimers in vivo.
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Affiliation(s)
- Pascal G. P. Martin
- *Laboratoire de Pharmacologie et Toxicologie, I.N.R.A., BP3, Toulouse, France
| | - Frédéric Lasserre
- *Laboratoire de Pharmacologie et Toxicologie, I.N.R.A., BP3, Toulouse, France
| | - Cécile Calleja
- *Laboratoire de Pharmacologie et Toxicologie, I.N.R.A., BP3, Toulouse, France
| | - Armelle Van Es
- *Laboratoire de Pharmacologie et Toxicologie, I.N.R.A., BP3, Toulouse, France
| | - Alain Roulet
- *Laboratoire de Pharmacologie et Toxicologie, I.N.R.A., BP3, Toulouse, France
| | | | - Michela Cantiello
- ‡Dipartimento di Patologia Animale, Universita’degli Studi di Torino, Torino, Italy
| | - Romain Barnouin
- *Laboratoire de Pharmacologie et Toxicologie, I.N.R.A., BP3, Toulouse, France
| | | | - Thierry Pineau
- *Laboratoire de Pharmacologie et Toxicologie, I.N.R.A., BP3, Toulouse, France
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27
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Weindl G, Schäfer-Korting M, Schaller M, Korting HC. Peroxisome Proliferator-Activated Receptors and their Ligands. Drugs 2005; 65:1919-34. [PMID: 16162018 DOI: 10.2165/00003495-200565140-00002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Glucocorticoids have remained one of the most frequently used classes of drugs for the treatment of skin diseases since their introduction more than 50 years ago. As a result of the discovery of new members of the nuclear hormone receptor (NR) superfamily, alternative therapeutic interventions that target retinoid and vitamin D receptors have been developed. Peroxisome proliferator-activated receptors (PPARs) comprise another important NR subfamily, consisting of three different isotypes: PPARalpha, PPARdelta (PPARbeta) and PPARgamma. These NRs are activated by a variety of natural and synthetic ligands such as fatty acids, eicosanoids, and antidiabetic and antihyperlipidaemic agents. While these receptors are established as regulators of gene expression in lipid and glucose homeostasis, evidence is now accumulating that PPARs also play a crucial role in cutaneous biology. Results from in vitro and in vivo studies have indicated the involvement of PPARs in epidermal maturation, proliferation and differentiation, as well as in immune and inflammatory responses, carcinogenesis, hyperpigmentation and skin wound healing. Furthermore, treatment of psoriatic patients with PPARgamma activators (thiazolidinediones) has been shown to induce beneficial effects. However, the effects of PPAR ligands should be carefully evaluated to determine whether they are in fact mediated via PPAR-dependent mechanisms. Nonetheless, PPARs seem to have significant potential as therapeutic targets in skin inflammatory disorders.
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Affiliation(s)
- Günther Weindl
- Department of Dermatology, University of Tübingen, Tübingen, Germany.
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28
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Anderson SP, Dunn C, Laughter A, Yoon L, Swanson C, Stulnig TM, Steffensen KR, Chandraratna RAS, Gustafsson JA, Corton JC. Overlapping transcriptional programs regulated by the nuclear receptors peroxisome proliferator-activated receptor alpha, retinoid X receptor, and liver X receptor in mouse liver. Mol Pharmacol 2004; 66:1440-52. [PMID: 15371561 DOI: 10.1124/mol.104.005496] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Lipid homeostasis is controlled in part by the nuclear receptors peroxisome proliferator (PP)-activated receptor alpha (PPARalpha) and liver X receptor (LXR) through regulation of genes involved in fatty acid and cholesterol metabolism. Exposure to agonists of retinoid X receptor (RXR), the obligate heterodimer partner of PPARalpha, and LXR results in responses that partially overlap with those of PP. To better understand the gene networks regulated by these nuclear receptors, transcript profiles were generated from the livers of wild-type and PPARalpha-null mice exposed to the RXR pan-agonist 3,7-dimethyl-6S,7S-methano, 7-[1,1,4,4-tetramethyl-1,2,3,4-tetrahydronaphth-7-yl]-2E,4E-heptadienoic acid (AGN194,204) or the PPAR pan-agonist WY-14,643 (WY; pirinixic acid) and compared with the profiles from the livers of wild-type and LXRalpha/LXRbeta-null mice after exposure to the LXR agonist N-(2,2,2-trifluoroethyl)-N-[4-(2,2,2-trifluoro-1-hydroxy-1-trifluoromethylethyl)phenyl] sulfonamide (T0901317). All 218 WY-regulated genes altered in wild-type mice required PPARalpha. Remarkably, approximately 80% of genes regulated by AGN194,204 required PPARalpha including cell-cycle genes, consistent with AGN-induced hepatocyte proliferation having both PPARalpha-dependent and -independent components. Overlaps of approximately 31 to 62% in the transcript profiles of WY, AGN194,204, and T0901317 required PPARalpha and LXRalpha/LXRbeta for statistical significance. Ofthe 50 overlapping genes regulated by T0901317 and WY, all but one were regulated in a similar direction. These results 1) identify new transcriptional targets of PPARalpha and RXR important in regulating lipid metabolism and liver homeostasis, 2) illustrate the importance of PPARalpha in regulation of gene expression by a prototypical PP and by an RXR agonist, and 3) provide support for an axis of PPARalpha-RXR-LXR in which agonists for each nuclear receptor regulate an overlapping set of genes in the mouse liver.
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Affiliation(s)
- Steven P Anderson
- Investigative Toxicology and Pathology Group, Safety Assessment, GlaxoSmithKline Research and Development, Research Triangle Park, North Carolina, USA
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29
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IJpenberg A, Tan NS, Gelman L, Kersten S, Seydoux J, Xu J, Metzger D, Canaple L, Chambon P, Wahli W, Desvergne B. In vivo activation of PPAR target genes by RXR homodimers. EMBO J 2004; 23:2083-91. [PMID: 15103326 PMCID: PMC424365 DOI: 10.1038/sj.emboj.7600209] [Citation(s) in RCA: 154] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2003] [Accepted: 03/22/2004] [Indexed: 02/05/2023] Open
Abstract
The ability of a retinoid X receptor (RXR) to heterodimerize with many nuclear receptors, including LXR, PPAR, NGF1B and RAR, underscores its pivotal role within the nuclear receptor superfamily. Among these heterodimers, PPAR:RXR is considered an important signalling mediator of both PPAR ligands, such as fatty acids, and 9-cis retinoic acid (9-cis RA), an RXR ligand. In contrast, the existence of an RXR/9-cis RA signalling pathway independent of PPAR or any other dimerization partner remains disputed. Using in vivo chromatin immunoprecipitation, we now show that RXR homodimers can selectively bind to functional PPREs and induce transactivation. At the molecular level, this pathway requires stabilization of the homodimer-DNA complexes through ligand-dependent interaction with the coactivator SRC1 or TIF2. This pathway operates both in the absence and in the presence of PPAR, as assessed in cells carrying inactivating mutations in PPAR genes and in wild-type cells. In addition, this signalling pathway via PPREs is fully functional and can rescue the severe hypothermia phenotype observed in fasted PPARalpha-/- mice. These observations have important pharmacological implications for the development of new rexinoid-based treatments.
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Affiliation(s)
- Annemieke IJpenberg
- Center for Integrative Genomics, NCCR Frontiers in Genetics, University of Lausanne, Lausanne, Switzerland
| | - Nguan Soon Tan
- Center for Integrative Genomics, NCCR Frontiers in Genetics, University of Lausanne, Lausanne, Switzerland
| | - Laurent Gelman
- Center for Integrative Genomics, NCCR Frontiers in Genetics, University of Lausanne, Lausanne, Switzerland
| | - Sander Kersten
- Center for Integrative Genomics, NCCR Frontiers in Genetics, University of Lausanne, Lausanne, Switzerland
| | - Josiane Seydoux
- Centre Médical Universitaire, Département de Physiologie, Geneva, Switzerland
| | - Jianming Xu
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Daniel Metzger
- Institut de Génétique et de Biologie Moléculaire et Cellulaire/CNRS/INSERM/ULP/Collège de France, Illkirch, Strasbourg, France
| | - Laurence Canaple
- Center for Integrative Genomics, NCCR Frontiers in Genetics, University of Lausanne, Lausanne, Switzerland
| | - Pierre Chambon
- Institut de Génétique et de Biologie Moléculaire et Cellulaire/CNRS/INSERM/ULP/Collège de France, Illkirch, Strasbourg, France
| | - Walter Wahli
- Center for Integrative Genomics, NCCR Frontiers in Genetics, University of Lausanne, Lausanne, Switzerland
| | - Béatrice Desvergne
- Center for Integrative Genomics, NCCR Frontiers in Genetics, University of Lausanne, Lausanne, Switzerland
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