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Qin Y, Bily D, Aguirre M, Zhang K, Xie L. Understanding PPARγ and Its Agonists on Trophoblast Differentiation and Invasion: Potential Therapeutic Targets for Gestational Diabetes Mellitus and Preeclampsia. Nutrients 2023; 15:nu15112459. [PMID: 37299422 DOI: 10.3390/nu15112459] [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: 04/17/2023] [Revised: 05/16/2023] [Accepted: 05/22/2023] [Indexed: 06/12/2023] Open
Abstract
The increasing incidence of pregnancy complications, particularly gestational diabetes mellitus (GDM) and preeclampsia (PE), is a cause for concern, as they can result in serious health consequences for both mothers and infants. The pathogenesis of these complications is still not fully understood, although it is known that the pathologic placenta plays a crucial role. Studies have shown that PPARγ, a transcription factor involved in glucose and lipid metabolism, may have a critical role in the etiology of these complications. While PPARγ agonists are FDA-approved drugs for Type 2 Diabetes Mellitus, their safety during pregnancy is not yet established. Nevertheless, there is growing evidence for the therapeutic potential of PPARγ in the treatment of PE using mouse models and in cell cultures. This review aims to summarize the current understanding of the mechanism of PPARγ in placental pathophysiology and to explore the possibility of using PPARγ ligands as a treatment option for pregnancy complications. Overall, this topic is of great significance for improving maternal and fetal health outcomes and warrants further investigation.
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Affiliation(s)
- Yushu Qin
- Department of Nutrition, Texas A&M University, College Station, TX 77843, USA
| | - Donalyn Bily
- Department of Nutrition, Texas A&M University, College Station, TX 77843, USA
- Department of Biology, Texas A&M University, College Station, TX 77843, USA
| | - Makayla Aguirre
- Department of Nutrition, Texas A&M University, College Station, TX 77843, USA
| | - Ke Zhang
- Department of Nutrition, Texas A&M University, College Station, TX 77843, USA
- Institute of Biosciences and Technology, Texas A&M University, Houston, TX 77030, USA
| | - Linglin Xie
- Department of Nutrition, Texas A&M University, College Station, TX 77843, USA
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2
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Nartey MNN, Jisaka M, Syeda PK, Nishimura K, Shimizu H, Yokota K. Prostaglandin D 2 Added during the Differentiation of 3T3-L1 Cells Suppresses Adipogenesis via Dysfunction of D-Prostanoid Receptor P1 and P2. Life (Basel) 2023; 13:life13020370. [PMID: 36836727 PMCID: PMC9963520 DOI: 10.3390/life13020370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Revised: 01/20/2023] [Accepted: 01/27/2023] [Indexed: 01/31/2023] Open
Abstract
We previously reported that the addition of prostaglandin, (PG)D2, and its chemically stable analog, 11-deoxy-11-methylene-PGD2 (11d-11m-PGD2), during the maturation phase of 3T3-L1 cells promotes adipogenesis. In the present study, we aimed to elucidate the effects of the addition of PGD2 or 11d-11m-PGD2 to 3T3-L1 cells during the differentiation phase on adipogenesis. We found that both PGD2 and 11d-11m-PGD2 suppressed adipogenesis through the downregulation of peroxisome proliferator-activated receptor gamma (PPARγ) expression. However, the latter suppressed adipogenesis more potently than PGD2, most likely because of its higher resistance to spontaneous transformation into PGJ2 derivatives. In addition, this anti-adipogenic effect was attenuated by the coexistence of an IP receptor agonist, suggesting that the effect depends on the intensity of the signaling from the IP receptor. The D-prostanoid receptors 1 (DP1) and 2 (DP2, also known as a chemoattractant receptor-homologous molecule expressed on Th2 cells) are receptors for PGD2. The inhibitory effects of PGD2 and 11d-11m-PGD2 on adipogenesis were slightly attenuated by a DP2 agonist. Furthermore, the addition of PGD2 and 11d-11m-PGD2 during the differentiation phase reduced the DP1 and DP2 expression during the maturation phase. Overall, these results indicated that the addition of PGD2 or 11d-11m-PGD2 during the differentiation phase suppresses adipogenesis via the dysfunction of DP1 and DP2. Therefore, unidentified receptor(s) for both molecules may be involved in the suppression of adipogenesis.
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Affiliation(s)
- Michael N. N. Nartey
- The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan
- Council for Scientific and Industrial Research-Animal Research Institute, Achimota, Accra P.O. Box AH20, Ghana
| | - Mitsuo Jisaka
- The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan
- Department of Life Science and Biotechnology, Shimane University, 1060 Nishikawatsu-Cho, Matsue 690-8504, Japan
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, 1060 Nishikawatsu-Cho, Matsue 690-8504, Japan
- Correspondence:
| | - Pinky Karim Syeda
- Department of Life Science and Biotechnology, Shimane University, 1060 Nishikawatsu-Cho, Matsue 690-8504, Japan
| | - Kohji Nishimura
- The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan
- Department of Life Science and Biotechnology, Shimane University, 1060 Nishikawatsu-Cho, Matsue 690-8504, Japan
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, 1060 Nishikawatsu-Cho, Matsue 690-8504, Japan
- Interdisciplinary Center for Science Research, Shimane University, 1060 Nishikawatsu-Cho, Matsue 690-8504, Japan
| | - Hidehisa Shimizu
- The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan
- Department of Life Science and Biotechnology, Shimane University, 1060 Nishikawatsu-Cho, Matsue 690-8504, Japan
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, 1060 Nishikawatsu-Cho, Matsue 690-8504, Japan
- Interdisciplinary Center for Science Research, Shimane University, 1060 Nishikawatsu-Cho, Matsue 690-8504, Japan
| | - Kazushige Yokota
- The United Graduate School of Agricultural Sciences, Tottori University, 4-101 Koyama-Minami, Tottori 680-8553, Japan
- Department of Life Science and Biotechnology, Shimane University, 1060 Nishikawatsu-Cho, Matsue 690-8504, Japan
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, 1060 Nishikawatsu-Cho, Matsue 690-8504, Japan
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3
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Yoshizawa M, Aoyama T, Itoh T, Miyachi H. Arylalkynyl amide-type peroxisome proliferator-activated receptor γ (PPARγ)-selective antagonists covalently bind to the PPARγ ligand binding domain with a unique binding mode. Bioorg Med Chem Lett 2022; 64:128676. [PMID: 35301139 DOI: 10.1016/j.bmcl.2022.128676] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 03/02/2022] [Accepted: 03/11/2022] [Indexed: 11/19/2022]
Abstract
Peroxisome proliferator-activated receptor γ (PPARγ) antagonists are drug candidates for the treatment of type 2 diabetes, obesity, and osteoporosis. Previously, we have designed and synthesized a series of substituted phenylalkynyl amide-type PPARγ antagonists. The representative compound, MMT-160, exhibited nanomolar-order PPARγ antagonistic activity. To understand the antagonistic mode of action of MMT-160, mass spectrometric and X-ray crystallographic analysis of MMT-160 in the presence of the PPARγ ligand binding domain (LBD) were performed. The mass spectrometry results clearly indicated that alkynyl amide-type PPARγ antagonists were covalently bound to the PPARγ LBD. The X-ray crystallographic analysis indicated that MMT-160 acted as a Michael acceptor and covalently bound to the PPARγ LBD via Cys285. In addition, MMT-160 bound to the PPARγ LBD with a binding mode that was different from the binding modes observed for PPARγ agonists and partial agonists.
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Affiliation(s)
- Mami Yoshizawa
- Laboratory of Drug Design and Medicinal Chemistry, Showa Pharmaceutical University, 3-3165 Higashi-Tamagawagakuen, Machida, Tokyo 194-8543, Japan
| | - Tomomi Aoyama
- Laboratory of Drug Design and Medicinal Chemistry, Showa Pharmaceutical University, 3-3165 Higashi-Tamagawagakuen, Machida, Tokyo 194-8543, Japan
| | - Toshimasa Itoh
- Laboratory of Drug Design and Medicinal Chemistry, Showa Pharmaceutical University, 3-3165 Higashi-Tamagawagakuen, Machida, Tokyo 194-8543, Japan
| | - Hiroyuki Miyachi
- Lead Exploration Unit, Drug Discovery Initiative, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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4
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Peroxisome proliferator-activated receptor gamma (PPARγ), a key regulatory gene of lipid metabolism in chicken. WORLD POULTRY SCI J 2019. [DOI: 10.1017/s0043933916000684] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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5
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Ohashi M, Miyachi H. Design and Synthesis of Peroxisome Proliferator-activated Receptor (PPAR) Gamma Antagonists Based on the Principle of Operation of Nuclear Receptor I. YAKUGAKU ZASSHI 2017; 137:957-967. [DOI: 10.1248/yakushi.17-00047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Masao Ohashi
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University
| | - Hiroyuki Miyachi
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University
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6
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Sharifi T, Ghayeb Y. A computational study to identify the key residues of peroxisome proliferator-activated receptor gamma in the interactions with its antagonists. J Biomol Struct Dyn 2017; 36:1822-1833. [DOI: 10.1080/07391102.2017.1335618] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Tayebeh Sharifi
- Department of Chemistry, Isfahan University of Technology , Isfahan, Iran
| | - Yousef Ghayeb
- Department of Chemistry, Isfahan University of Technology , Isfahan, Iran
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7
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Cordonier EL, Jarecke SK, Hollinger FE, Zempleni J. Inhibition of acetyl-CoA carboxylases by soraphen A prevents lipid accumulation and adipocyte differentiation in 3T3-L1 cells. Eur J Pharmacol 2016; 780:202-8. [PMID: 27041646 DOI: 10.1016/j.ejphar.2016.03.052] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 03/22/2016] [Accepted: 03/29/2016] [Indexed: 10/22/2022]
Abstract
Acetyl-CoA carboxylases (ACC) 1 and 2 catalyze the carboxylation of acetyl-CoA to malonyl-CoA and depend on biotin as a coenzyme. ACC1 localizes in the cytoplasm and produces malonyl-CoA for fatty acid (FA) synthesis. ACC2 localizes in the outer mitochondrial membrane and produces malonyl-CoA that inhibits FA import into mitochondria for subsequent oxidation. We hypothesized that ACCs are checkpoints in adipocyte differentiation and tested this hypothesis using the ACC1 and ACC2 inhibitor soraphen A (SA) in murine 3T3-L1 preadipocytes. When 3T3-L1 cells were treated with 100nM SA for 8 days after induction of differentiation, the expression of PPARγ mRNA and FABP4 mRNA decreased by 40% and 50%, respectively, compared with solvent controls; the decrease in gene expression was accompanied by a decrease in FABP4 protein expression and associated with a decrease in lipid droplet accumulation. The rate of FA oxidation was 300% greater in SA-treated cells compared with vehicle controls. Treatment with exogenous palmitate restored PPARγ and FABP4 mRNA expression and FABP4 protein expression in SA-treated cells. In contrast, SA did not alter lipid accumulation if treatment was initiated on day eight after induction of differentiation. We conclude that loss of ACC1-dependent FA synthesis and loss of ACC2-dependent inhibition of FA oxidation prevent lipid accumulation in adipocytes and inhibit early stages of adipocyte differentiation.
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Affiliation(s)
- Elizabeth L Cordonier
- Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, 316 Leverton Hall, Lincoln, NE 68583-0806, USA
| | - Sarah K Jarecke
- Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, 316 Leverton Hall, Lincoln, NE 68583-0806, USA
| | - Frances E Hollinger
- Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, 316 Leverton Hall, Lincoln, NE 68583-0806, USA
| | - Janos Zempleni
- Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, 316 Leverton Hall, Lincoln, NE 68583-0806, USA.
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8
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Hallenborg P, Petersen RK, Kouskoumvekaki I, Newman JW, Madsen L, Kristiansen K. The elusive endogenous adipogenic PPARγ agonists: Lining up the suspects. Prog Lipid Res 2016; 61:149-62. [DOI: 10.1016/j.plipres.2015.11.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 11/06/2015] [Accepted: 11/10/2015] [Indexed: 02/07/2023]
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9
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Witte N, Muenzner M, Rietscher J, Knauer M, Heidenreich S, Nuotio-Antar AM, Graef FA, Fedders R, Tolkachov A, Goehring I, Schupp M. The Glucose Sensor ChREBP Links De Novo Lipogenesis to PPARγ Activity and Adipocyte Differentiation. Endocrinology 2015; 156:4008-19. [PMID: 26181104 DOI: 10.1210/en.2015-1209] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Reduced de novo lipogenesis in adipose tissue, often observed in obese individuals, is thought to contribute to insulin resistance. Besides trapping excess glucose and providing for triglycerides and energy storage, endogenously synthesized lipids can function as potent signaling molecules. Indeed, several specific lipids and their molecular targets that mediate insulin sensitivity have been recently identified. Here, we report that carbohydrate-response element-binding protein (ChREBP), a transcriptional inducer of glucose use and de novo lipogenesis, controls the activity of the adipogenic master regulator peroxisome proliferator-activated receptor (PPAR)γ. Expression of constitutive-active ChREBP in precursor cells activated endogenous PPARγ and promoted adipocyte differentiation. Intriguingly, ChREBP-constitutive-active ChREBP expression induced PPARγ activity in a fatty acid synthase-dependent manner and by trans-activating the PPARγ ligand-binding domain. Reducing endogenous ChREBP activity by either small interfering RNA-mediated depletion, exposure to low-glucose concentrations, or expressing a dominant-negative ChREBP impaired differentiation. In adipocytes, ChREBP regulated the expression of PPARγ target genes, in particular those involved in thermogenesis, similar to synthetic PPARγ ligands. In summary, our data suggest that ChREBP controls the generation of endogenous fatty acid species that activate PPARγ. Thus, increasing ChREBP activity in adipose tissue by therapeutic interventions may promote insulin sensitivity through PPARγ.
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Affiliation(s)
- Nicole Witte
- Charité University School of Medicine (N.W., M.M., J.R., M.K., S.H., F.A.G., R.F., A.T., I.G., M.S.), Institute of Pharmacology, Center for Cardiovascular Research, Berlin 10115, Germany; and Department of Pediatrics (A.M.N.-A.), Baylor College of Medicine, Children's Nutritional Research Center, Houston, Texas 77030
| | - Matthias Muenzner
- Charité University School of Medicine (N.W., M.M., J.R., M.K., S.H., F.A.G., R.F., A.T., I.G., M.S.), Institute of Pharmacology, Center for Cardiovascular Research, Berlin 10115, Germany; and Department of Pediatrics (A.M.N.-A.), Baylor College of Medicine, Children's Nutritional Research Center, Houston, Texas 77030
| | - Janita Rietscher
- Charité University School of Medicine (N.W., M.M., J.R., M.K., S.H., F.A.G., R.F., A.T., I.G., M.S.), Institute of Pharmacology, Center for Cardiovascular Research, Berlin 10115, Germany; and Department of Pediatrics (A.M.N.-A.), Baylor College of Medicine, Children's Nutritional Research Center, Houston, Texas 77030
| | - Miriam Knauer
- Charité University School of Medicine (N.W., M.M., J.R., M.K., S.H., F.A.G., R.F., A.T., I.G., M.S.), Institute of Pharmacology, Center for Cardiovascular Research, Berlin 10115, Germany; and Department of Pediatrics (A.M.N.-A.), Baylor College of Medicine, Children's Nutritional Research Center, Houston, Texas 77030
| | - Steffi Heidenreich
- Charité University School of Medicine (N.W., M.M., J.R., M.K., S.H., F.A.G., R.F., A.T., I.G., M.S.), Institute of Pharmacology, Center for Cardiovascular Research, Berlin 10115, Germany; and Department of Pediatrics (A.M.N.-A.), Baylor College of Medicine, Children's Nutritional Research Center, Houston, Texas 77030
| | - Alli M Nuotio-Antar
- Charité University School of Medicine (N.W., M.M., J.R., M.K., S.H., F.A.G., R.F., A.T., I.G., M.S.), Institute of Pharmacology, Center for Cardiovascular Research, Berlin 10115, Germany; and Department of Pediatrics (A.M.N.-A.), Baylor College of Medicine, Children's Nutritional Research Center, Houston, Texas 77030
| | - Franziska A Graef
- Charité University School of Medicine (N.W., M.M., J.R., M.K., S.H., F.A.G., R.F., A.T., I.G., M.S.), Institute of Pharmacology, Center for Cardiovascular Research, Berlin 10115, Germany; and Department of Pediatrics (A.M.N.-A.), Baylor College of Medicine, Children's Nutritional Research Center, Houston, Texas 77030
| | - Ronja Fedders
- Charité University School of Medicine (N.W., M.M., J.R., M.K., S.H., F.A.G., R.F., A.T., I.G., M.S.), Institute of Pharmacology, Center for Cardiovascular Research, Berlin 10115, Germany; and Department of Pediatrics (A.M.N.-A.), Baylor College of Medicine, Children's Nutritional Research Center, Houston, Texas 77030
| | - Alexander Tolkachov
- Charité University School of Medicine (N.W., M.M., J.R., M.K., S.H., F.A.G., R.F., A.T., I.G., M.S.), Institute of Pharmacology, Center for Cardiovascular Research, Berlin 10115, Germany; and Department of Pediatrics (A.M.N.-A.), Baylor College of Medicine, Children's Nutritional Research Center, Houston, Texas 77030
| | - Isabel Goehring
- Charité University School of Medicine (N.W., M.M., J.R., M.K., S.H., F.A.G., R.F., A.T., I.G., M.S.), Institute of Pharmacology, Center for Cardiovascular Research, Berlin 10115, Germany; and Department of Pediatrics (A.M.N.-A.), Baylor College of Medicine, Children's Nutritional Research Center, Houston, Texas 77030
| | - Michael Schupp
- Charité University School of Medicine (N.W., M.M., J.R., M.K., S.H., F.A.G., R.F., A.T., I.G., M.S.), Institute of Pharmacology, Center for Cardiovascular Research, Berlin 10115, Germany; and Department of Pediatrics (A.M.N.-A.), Baylor College of Medicine, Children's Nutritional Research Center, Houston, Texas 77030
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10
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Horiba T, Katsukawa M, Mita M, Sato R. Dietary obacunone supplementation stimulates muscle hypertrophy, and suppresses hyperglycemia and obesity through the TGR5 and PPARγ pathway. Biochem Biophys Res Commun 2015; 463:846-52. [DOI: 10.1016/j.bbrc.2015.06.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 06/03/2015] [Indexed: 01/22/2023]
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11
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Fratev F, Tsakovska I, Al Sharif M, Mihaylova E, Pajeva I. Structural and Dynamical Insight into PPARγ Antagonism: In Silico Study of the Ligand-Receptor Interactions of Non-Covalent Antagonists. Int J Mol Sci 2015; 16:15405-24. [PMID: 26184155 PMCID: PMC4519905 DOI: 10.3390/ijms160715405] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 06/26/2015] [Accepted: 06/30/2015] [Indexed: 01/14/2023] Open
Abstract
The structural and dynamical properties of the peroxisome proliferator-activated receptor γ (PPARγ) nuclear receptor have been broadly studied in its agonist state but little is known about the key features required for the receptor antagonistic activity. Here we report a series of molecular dynamics (MD) simulations in combination with free energy estimation of the recently discovered class of non-covalent PPARγ antagonists. Their binding modes and dynamical behavior are described in details. Two key interactions have been detected within the cavity between helices H3, H11 and the activation helix H12, as well as with H12. The strength of the ligand-amino acid residues interactions has been analyzed in relation to the specificity of the ligand dynamical and antagonistic features. According to our results, the PPARγ activation helix does not undergo dramatic conformational changes, as seen in other nuclear receptors, but rather perturbations that occur through a significant ligand-induced reshaping of the ligand-receptor and the receptor-coactivator binding pockets. The H12 residue Tyr473 and the charge clamp residue Glu471 play a central role for the receptor transformations. Our results also demonstrate that MD can be a helpful tool for the compound phenotype characterization (full agonists, partial agonists or antagonists) when insufficient experimental data are available.
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Affiliation(s)
- Filip Fratev
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
- Micar21 Ltd., 1407 Sofia, Bulgaria.
| | - Ivanka Tsakovska
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
| | - Merilin Al Sharif
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
| | | | - Ilza Pajeva
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
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12
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Ohashi M, Gamo K, Tanaka Y, Waki M, Beniyama Y, Matsuno K, Wada J, Tenta M, Eguchi J, Makishima M, Matsuura N, Oyama T, Miyachi H. Structural design and synthesis of arylalkynyl amide-type peroxisome proliferator-activated receptor γ (PPARγ)-selective antagonists based on the helix12-folding inhibition hypothesis. Eur J Med Chem 2015; 90:53-67. [DOI: 10.1016/j.ejmech.2014.11.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 11/05/2014] [Accepted: 11/06/2014] [Indexed: 01/13/2023]
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13
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Nishimura S, Nagasaki M, Okudaira S, Aoki J, Ohmori T, Ohkawa R, Nakamura K, Igarashi K, Yamashita H, Eto K, Uno K, Hayashi N, Kadowaki T, Komuro I, Yatomi Y, Nagai R. ENPP2 contributes to adipose tissue expansion and insulin resistance in diet-induced obesity. Diabetes 2014; 63:4154-64. [PMID: 24969110 DOI: 10.2337/db13-1694] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Body weight is tightly regulated by food intake and energy dissipation, and obesity is related to decreased energy expenditure (EE). Herein, we show that nucleotide pyrophosphatase/phosphodiesterase 2 (ENPP2, autotaxin) is an adipose-derived, secreted enzyme that controls adipose expansion, brown adipose tissue (BAT) function, and EE. In mice, Enpp2 was highly expressed in visceral white adipose tissue and BAT and is downregulated in hypertrophied adipocytes/adipose tissue. Enpp2(+/-) mice and adipocyte-specific Enpp2 knockout mice fed a high-fat diet showed smaller body weight gains and less insulin resistance than control mice fed the same diet. BAT was functionally more active and EE was increased in Enpp2-deficient mice. In humans, ENPP2 expression in subcutaneous fat and ENPP2 levels in serum were reduced in obese subjects. Taken together, our results establish ENPP2 as an adipose-derived, secreted enzyme that regulates adipose obesity and systemic metabolism. They also suggest ENPP2 could be a useful therapeutic target for the treatment of metabolic disease.
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Affiliation(s)
- Satoshi Nishimura
- Department of Cardiovascular Medicine, University of Tokyo, Tokyo, Japan Translational Systems Biology and Medicine Initiative, University of Tokyo, Tokyo, Japan Research Division of Cell and Molecular Medicine, Center for Molecular Medicine, Jichi Medical University, Tochigi, Japan
| | - Mika Nagasaki
- Department of Cardiovascular Medicine, University of Tokyo, Tokyo, Japan Computational Diagnostic Radiology and Preventive Medicine, University of Tokyo, Tokyo, Japan
| | - Shinichi Okudaira
- Department of Molecular and Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Miygai, Japan
| | - Junken Aoki
- Department of Molecular and Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Miygai, Japan
| | - Tsukasa Ohmori
- Research Division of Cell and Molecular Medicine, Center for Molecular Medicine, Jichi Medical University, Tochigi, Japan
| | - Ryunosuke Ohkawa
- Department of Clinical Laboratory, University of Tokyo Hospital, Tokyo, Japan
| | - Kazuhiro Nakamura
- Department of Clinical Laboratory, University of Tokyo Hospital, Tokyo, Japan
| | - Koji Igarashi
- Bioscience Division, Reagent Development Department, AIA Research Group, Tosoh Corporation, Kanagawa, Japan
| | - Hiroshi Yamashita
- Department of Cardiovascular Medicine, University of Tokyo, Tokyo, Japan
| | - Koji Eto
- Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan
| | - Kansei Uno
- Department of Cardiovascular Medicine, University of Tokyo, Tokyo, Japan Computational Diagnostic Radiology and Preventive Medicine, University of Tokyo, Tokyo, Japan
| | - Naoto Hayashi
- Computational Diagnostic Radiology and Preventive Medicine, University of Tokyo, Tokyo, Japan
| | - Takashi Kadowaki
- Translational Systems Biology and Medicine Initiative, University of Tokyo, Tokyo, Japan Department of Metabolic Diseases, University of Tokyo, Tokyo, Japan
| | - Issei Komuro
- Department of Cardiovascular Medicine, University of Tokyo, Tokyo, Japan
| | - Yutaka Yatomi
- Department of Clinical Laboratory, University of Tokyo Hospital, Tokyo, Japan
| | - Ryozo Nagai
- Research Division of Cell and Molecular Medicine, Center for Molecular Medicine, Jichi Medical University, Tochigi, Japan
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14
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Hallenborg P, Petersen RK, Feddersen S, Sundekilde U, Hansen JB, Blagoev B, Madsen L, Kristiansen K. PPARγ ligand production is tightly linked to clonal expansion during initiation of adipocyte differentiation. J Lipid Res 2014; 55:2491-500. [PMID: 25312885 DOI: 10.1194/jlr.m050658] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Adipocyte differentiation is orchestrated by the ligand-activated nuclear receptor PPARγ. Endogenous ligands comprise oxidized derivatives of arachidonic acid and structurally similar PUFAs. Although expression of PPARγ peaks in mature adipocytes, ligands are produced primarily at the onset of differentiation. Concomitant with agonist production, murine fibroblasts undergo two rounds of mitosis referred to as mitotic clonal expansion. Here we show that mouse embryonic fibroblasts deficient in either of two cell cycle inhibitors, the transcription factor p53 or its target gene encoding the cyclin-dependent kinase inhibitor p21, exhibit increased adipogenic potential. The antiadipogenic effect of p53 relied on its transcriptional activity and p21 expression but was circumvented by administration of an exogenous PPARγ agonist suggesting a linkage between cell cycling and PPARγ ligand production. Indeed, cell cycle inhibitory compounds decreased PPARγ ligand production in differentiating 3T3-L1 preadipocytes. Furthermore, these inhibitors abolished the release of arachidonic acid induced by the hormonal cocktail initiating adipogenesis. Collectively, our results suggest that murine fibroblasts require clonal expansion for PPARγ ligand production at the onset of adipocyte differentiation.
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Affiliation(s)
- Philip Hallenborg
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | | | - Søren Feddersen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Ulrik Sundekilde
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Jacob B Hansen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Blagoy Blagoev
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Lise Madsen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark National Institute of Nutrition and Seafood Research, Bergen, Norway
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15
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Lin J, Tang Y, Kang Q, Feng Y, Chen A. Curcumin inhibits gene expression of receptor for advanced glycation end-products (RAGE) in hepatic stellate cells in vitro by elevating PPARγ activity and attenuating oxidative stress. Br J Pharmacol 2012; 166:2212-27. [PMID: 22352842 DOI: 10.1111/j.1476-5381.2012.01910.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND AND PURPOSE Diabetes is characterized by hyperglycaemia, which facilitates the formation of advanced glycation end-products (AGEs). Type 2 diabetes mellitus is commonly accompanied by non-alcoholic steatohepatitis, which could lead to hepatic fibrosis. Receptor for AGEs (RAGE) mediates effects of AGEs and is associated with increased oxidative stress, cell growth and inflammation. The phytochemical curcumin inhibits the activation of hepatic stellate cells (HSCs), the major effectors during hepatic fibrogenesis. The aim of this study was to explore the underlying mechanisms of curcumin in the elimination of the stimulating effects of AGEs on the activation of HSCs. We hypothesize that curcumin eliminates the effects of AGEs by suppressing gene expression of RAGE. EXPERIMENTAL APPROACH Gene promoter activities were evaluated by transient transfection assays. The expression of rage was silenced by short hairpin RNA. Gene expression was analysed by real-time PCR and Western blots. Oxidative stress was evaluated. KEY RESULTS AGEs induced rage expression in cultured HSCs, which played a critical role in the AGEs-induced activation of HSCs. Curcumin at 20 µM eliminated the AGE effects, which required the activation of PPARγ. In addition, curcumin attenuated AGEs-induced oxidative stress in HSCs by elevating the activity of glutamate-cysteine ligase and by stimulating de novo synthesis of glutathione, leading to the suppression of gene expression of RAGE. CONCLUSION AND IMPLICATIONS Curcumin suppressed gene expression of RAGE by elevating the activity of PPARγ and attenuating oxidative stress, leading to the elimination of the AGE effects on the activation of HSCs. LINKED ARTICLE This article is commented on by Stefanska, pp. 2209-2211 of this issue. To view this commentary visit http://dx.doi.org/10.1111/j.1476-5381.2012.01959.x.
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Affiliation(s)
- Jianguo Lin
- Department of Pathology, School of Medicine, Saint Louis University, St. Louis, MO 63104, USA
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16
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Curcumin eliminates the inhibitory effect of advanced glycation end-products (AGEs) on gene expression of AGE receptor-1 in hepatic stellate cells in vitro. J Transl Med 2012; 92:827-41. [PMID: 22449800 PMCID: PMC3365656 DOI: 10.1038/labinvest.2012.53] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Diabetes is featured by hyperglycemia, which facilitates the formation of advanced glycation end-products (AGEs). AGEs are a causal factor in development of diabetic complications. AGE receptor-1 (AGE-R1) is responsible for detoxification and clearance of AGEs. Type 2 diabetes mellitus is commonly accompanied by non-alcoholic steatohepatitis, which could cause hepatic fibrosis. Little attention has been paid to effects of AGEs on hepatic fibrogenesis. Curcumin, a phytochemical from turmeric, has been reported to inhibit the activation of hepatic stellate cells (HSCs), the major effectors during hepatic fibrogenesis, and to protect against hepatic fibrogenesis in vitro and in vivo. The current study was designed to evaluate the effects of AGEs on inducing HSC activation, to assess the role of curcumin in diminishing the AGE effects, and to explore the underlying mechanisms. Our results showed that AGEs stimulated HSC activation by inducing cell proliferation and expression of genes relevant to HSC activation, which were abrogated by curcumin. Curcumin induced gene expression of AGE-R1 in passaged HSCs, which might facilitate the attenuation of the stimulatory effects of AGEs on the activation of HSCs. Further experiments revealed that curcumin inhibited the activity of extracellular signal-regulated kinase (ERK), and induced gene expression and the activity of peroxisome proliferator-activated receptor-gamma (PPARγ), leading to the induction of the AGE-R1 gene expression. In summary, AGEs stimulated HSC activation. Curcumin eliminated the AGE effects at least partially by inducing the AGE-R1 gene expression. The process was mediated by inhibiting ERK activity, inducing gene expression of PPARγ and stimulating its transactivity.
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17
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Tsukahara T. The Role of PPARγ in the Transcriptional Control by Agonists and Antagonists. PPAR Res 2012; 2012:362361. [PMID: 22693486 PMCID: PMC3368591 DOI: 10.1155/2012/362361] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Accepted: 04/02/2012] [Indexed: 01/04/2023] Open
Abstract
In recent years, peroxisome proliferator-activated receptor gamma (PPARγ) has been reported to be a target for the treatment of type II diabetes. Furthermore, it has received attention for its therapeutic potential in many other human diseases, including atherosclerosis, obesity, and cancers. Recent studies have provided evidence that the endogenously produced PPARγ antagonist, 2,3-cyclic phosphatidic acid (cPA), which is similar in structure to lysophosphatidic acid (LPA), inhibits cancer cell invasion and metastasis in vitro and in vivo. We recently observed that cPA negatively regulates PPARγ function by stabilizing the binding of the corepressor protein, silencing mediator of retinoic acid and thyroid hormone receptor. We also showed that cPA prevents neointima formation, adipocyte differentiation, lipid accumulation, and upregulation of PPARγ target gene transcription. We then analyzed the molecular mechanism of cPA's action on PPARγ. In this paper, we summarize the current knowledge on the mechanism of PPARγ-mediated transcriptional activity and transcriptional repression in response to novel lipid-derived ligands, such as cPA.
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Affiliation(s)
- Tamotsu Tsukahara
- Department of Integrative Physiology and Bio-System Control, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan
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18
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Pirat C, Farce A, Lebègue N, Renault N, Furman C, Millet R, Yous S, Speca S, Berthelot P, Desreumaux P, Chavatte P. Targeting Peroxisome Proliferator-Activated Receptors (PPARs): Development of Modulators. J Med Chem 2012; 55:4027-61. [DOI: 10.1021/jm101360s] [Citation(s) in RCA: 139] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Céline Pirat
- Laboratoire de Chimie Thérapeutique,
Faculté des Sciences Pharmaceutiques et Biologiques, Université Lille-Nord de France, EA 4481, 3
Rue du Professeur Laguesse, BP 83, 59006 Lille Cedex, France
| | - Amaury Farce
- Laboratoire de Chimie Thérapeutique,
Faculté des Sciences Pharmaceutiques et Biologiques, Université Lille-Nord de France, EA 4481, 3
Rue du Professeur Laguesse, BP 83, 59006 Lille Cedex, France
| | - Nicolas Lebègue
- Laboratoire de Chimie Thérapeutique,
Faculté des Sciences Pharmaceutiques et Biologiques, Université Lille-Nord de France, EA 4481, 3
Rue du Professeur Laguesse, BP 83, 59006 Lille Cedex, France
| | - Nicolas Renault
- Laboratoire de Chimie Thérapeutique,
Faculté des Sciences Pharmaceutiques et Biologiques, Université Lille-Nord de France, EA 4481, 3
Rue du Professeur Laguesse, BP 83, 59006 Lille Cedex, France
| | - Christophe Furman
- Institut de Chimie Pharmaceutique
Albert Lespagnol, Université Lille-Nord de France, EA 4481, 3 Rue du Professeur Laguesse, BP 83, 59006 Lille Cedex,
France
| | - Régis Millet
- Institut de Chimie Pharmaceutique
Albert Lespagnol, Université Lille-Nord de France, EA 4481, 3 Rue du Professeur Laguesse, BP 83, 59006 Lille Cedex,
France
| | - Saı̈d Yous
- Laboratoire de Chimie Thérapeutique,
Faculté des Sciences Pharmaceutiques et Biologiques, Université Lille-Nord de France, EA 4481, 3
Rue du Professeur Laguesse, BP 83, 59006 Lille Cedex, France
| | - Silvia Speca
- Faculté de
Médecine, Amphis J et K, Université Lille-Nord de France, INSERM U995, Boulevard du Professeur Jules
Leclerc, 59045 Lille Cedex, France
| | - Pascal Berthelot
- Laboratoire de Chimie Thérapeutique,
Faculté des Sciences Pharmaceutiques et Biologiques, Université Lille-Nord de France, EA 4481, 3
Rue du Professeur Laguesse, BP 83, 59006 Lille Cedex, France
| | - Pierre Desreumaux
- Faculté de
Médecine, Amphis J et K, Université Lille-Nord de France, INSERM U995, Boulevard du Professeur Jules
Leclerc, 59045 Lille Cedex, France
| | - Philippe Chavatte
- Laboratoire de Chimie Thérapeutique,
Faculté des Sciences Pharmaceutiques et Biologiques, Université Lille-Nord de France, EA 4481, 3
Rue du Professeur Laguesse, BP 83, 59006 Lille Cedex, France
- Institut de Chimie Pharmaceutique
Albert Lespagnol, Université Lille-Nord de France, EA 4481, 3 Rue du Professeur Laguesse, BP 83, 59006 Lille Cedex,
France
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19
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Epidermis-type lipoxygenase 3 regulates adipocyte differentiation and peroxisome proliferator-activated receptor gamma activity. Mol Cell Biol 2010; 30:4077-91. [PMID: 20530198 DOI: 10.1128/mcb.01806-08] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The nuclear receptor peroxisome proliferator-activated receptor gamma (PPAR gamma) is essential for adipogenesis. Although several fatty acids and their derivatives are known to bind and activate PPAR gamma, the nature of the endogenous ligand(s) promoting the early stages of adipocyte differentiation has remained enigmatic. Previously, we showed that lipoxygenase (LOX) activity is involved in activation of PPAR gamma during the early stages of adipocyte differentiation. Of the seven known murine LOXs, only the unconventional LOX epidermis-type lipoxygenase 3 (eLOX3) is expressed in 3T3-L1 preadipocytes. Here, we show that forced expression of eLOX3 or addition of eLOX3 products stimulated adipogenesis under conditions that normally require an exogenous PPAR gamma ligand for differentiation. Hepoxilins, a group of oxidized arachidonic acid derivatives produced by eLOX3, bound to and activated PPAR gamma. Production of hepoxilins was increased transiently during the initial stages of adipogenesis. Furthermore, small interfering RNA-mediated or retroviral short hairpin RNA-mediated knockdown of eLOX3 expression abolished differentiation of 3T3-L1 preadipocytes. Finally, we demonstrate that xanthine oxidoreductase (XOR) and eLOX3 synergistically enhanced PPAR gamma-mediated transactivation. Collectively, our results indicate that hepoxilins produced by the concerted action of XOR and eLOX3 may function as PPAR gamma activators capable of promoting the early PPAR gamma-dependent steps in the conversion of preadipocytes into adipocytes.
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20
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7-Chloroarctinone-b as a new selective PPARgamma antagonist potently blocks adipocyte differentiation. Acta Pharmacol Sin 2009; 30:1351-8. [PMID: 19684608 DOI: 10.1038/aps.2009.113] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
AIM Peroxisome proliferator-activated receptor gamma (PPARgamma) is a therapeutic target for obesity, cancer and diabetes mellitus. In order to develop potent lead compounds for obesity treatment, we screened a natural product library for novel PPARgamma antagonists with inhibitory effects on adipocyte differentiation. METHODS Surface plasmon resonance (SPR) technology and cell-based transactivation assay were used to screen for PPARgamma antagonists. To investigate the antagonistic mechanism of the active compound, we measured its effect on PPARgamma/RXRalpha heterodimerization and PPARgamma co-activator recruitment using yeast two-hybrid assay, Gal4/UAS cell-based assay and SPR based assay. The 3T3-L1 cell differentiation assay was used to evaluate the effect of the active compound on adipocyte differentiation. RESULTS A new thiophene-acetylene type of natural product, 7-chloroarctinone-b (CAB), isolated from the roots of Rhaponticum uniflorum, was discovered as a novel PPARgamma antagonist capable of inhibiting rosiglitazone-induced PPARgamma transcriptional activity. SPR analysis suggested that CAB bound tightly to PPARgamma and considerably antagonized the potent PPARgamma agonist rosiglitazone-stimulated PPARgamma-LBD/RXRalpha-LBD binding. Gal4/UAS and yeast two-hybrid assays were used to evaluate the antagonistic activity of CAB on rosiglitazone-induced recruitment of the coactivator for PPARgamma. CAB could efficiently antagonize both hormone and rosiglitazone-induced adipocyte differentiation in cell culture. CONCLUSION CAB shows antagonistic activity to PPARgamma and can block the adipocyte differentiation, indicating it may be of potential use as a lead therapeutic compound for obesity.
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21
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Abstract
Peroxisome proliferator-activated receptors (PPARs) belong to the nuclear hormone-receptor superfamily. Originally cloned in 1990, PPARs were found to be mediators of pharmacologic agents that induce hepatocyte peroxisome proliferation. PPARs also are expressed in cells of the cardiovascular system. PPAR gamma appears to be highly expressed during atherosclerotic lesion formation, suggesting that increased PPAR gamma expression may be a vascular compensatory response. Also, ligand-activated PPAR gamma decreases the inflammatory response in cardiovascular cells, particularly in endothelial cells. PPAR alpha, similar to PPAR gamma, also has pleiotropic effects in the cardiovascular system, including antiinflammatory and antiatherosclerotic properties. PPAR alpha activation inhibits vascular smooth muscle proinflammatory responses, attenuating the development of atherosclerosis. However, PPAR delta overexpression may lead to elevated macrophage inflammation and atherosclerosis. Conversely, PPAR delta ligands are shown to attenuate the pathogenesis of atherosclerosis by improving endothelial cell proliferation and survival while decreasing endothelial cell inflammation and vascular smooth muscle cell proliferation. Furthermore, the administration of PPAR ligands in the form of TZDs and fibrates has been disappointing in terms of markedly reducing cardiovascular events in the clinical setting. Therefore, a better understanding of PPAR-dependent and -independent signaling will provide the foundation for future research on the role of PPARs in human cardiovascular biology.
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Affiliation(s)
- Milton Hamblin
- Cardiovascular Center, Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, Michigan 48109, USA
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22
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PI-3 K/AKT and ERK signaling pathways mediate leptin-induced inhibition of PPARgamma gene expression in primary rat hepatic stellate cells. Mol Cell Biochem 2009; 325:131-9. [PMID: 19191008 DOI: 10.1007/s11010-009-0027-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2008] [Accepted: 01/15/2009] [Indexed: 01/18/2023]
Abstract
Compelling evidence indicates the pro-fibrogenic action of leptin in liver. Peroxisome proliferator-activated receptor-gamma (PPARgamma) can reverse hepatic stellate cell (HSC) activation and maintain HSC quiescence. HSC activation, a key step in the development of liver fibrosis, is coupled with the up-expression of leptin and the dramatic down-expression of PPARgamma. The present study is aimed to assess the effect of leptin on PPARgamma gene expression in primary cultured rat HSCs and investigate the related mechanisms by using Western blotting analysis, real-time PCR, transient transfection approach, and cell growth analysis. The results suggest that leptin negatively regulates PPARgamma gene expression at mRNA level, protein level and PPARgamma gene promoter activity level in HSCs. The inhibitory effect of leptin on PPARgamma gene expression contributes to cell growth of activated HSCs in vitro. Phosphatidylinositol 3-kinase/AKT (PI-3 K/AKT) and extracellular signal-regulated kinase (ERK) signaling pathways mediate the leptin-induced inhibition of PPARgamma gene expression. In summary, these findings suggest that leptin down-regulates PPARgamma gene expression through activation of PI-3 K/AKT or ERK signaling pathway in primary cultured rat HSCs. Our results might provide novel insights into the mechanisms for the pro-fibrogenic action of leptin in liver.
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23
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Retinol saturase promotes adipogenesis and is downregulated in obesity. Proc Natl Acad Sci U S A 2009; 106:1105-10. [PMID: 19139408 DOI: 10.1073/pnas.0812065106] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Adipocyte differentiation is controlled by many transcription factors, but few known downstream targets of these factors are necessary for adipogenesis. Here we report that retinol saturase (RetSat), which is an enzyme implicated in the generation of dihydroretinoid metabolites, is induced during adipogenesis and is directly regulated by the transcription factor peroxisome proliferator activated receptor gamma (PPARgamma). Ablation of RetSat dramatically inhibited adipogenesis but, surprisingly, this block was not overcome by the putative product of RetSat enzymatic activity. On the other hand, ectopic RetSat with an intact, but not a mutated, FAD/NAD dinucleotide-binding motif increased endogenous PPARgamma transcriptional activity and promoted adipogenesis. Indeed, RetSat was not required for adipogenesis when cells were provided with exogenous PPARgamma ligands. In adipose tissue, RetSat is expressed in adipocytes but is unexpectedly downregulated in obesity, most likely owing to infiltration of macrophages that we demonstrate to repress RetSat expression. Thiazolidinedione treatment reversed low RetSat expression in adipose tissue of obese mice. Thus, RetSat plays an important role in the biology of adipocytes, where it favors normal differentiation, yet is reduced in the obese state. RetSat is thus a novel target for therapeutic intervention in metabolic disease.
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24
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Franks PW, Jablonski KA, Delahanty L, Hanson RL, Kahn SE, Altshuler D, Knowler WC, Florez JC. The Pro12Ala variant at the peroxisome proliferator-activated receptor gamma gene and change in obesity-related traits in the Diabetes Prevention Program. Diabetologia 2007; 50:2451-60. [PMID: 17898990 PMCID: PMC2453532 DOI: 10.1007/s00125-007-0826-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2007] [Accepted: 08/10/2007] [Indexed: 12/25/2022]
Abstract
AIMS/HYPOTHESIS Peroxisome proliferator-activated receptor gamma (PPARgamma), encoded by the PPARG gene, regulates insulin sensitivity and adipogenesis, and may bind polyunsaturated fatty acids (PUFA) and thiazolidinediones in a ligand-dependent manner. The PPARG proline for alanine substitution at position 12 (Pro12Ala polymorphism) has been related with obesity directly and via interaction with PUFA. METHODS We tested the effect-modifying role of Pro12Ala on the 1 year change in obesity-related traits in a randomised clinical trial of treatment with metformin (n = 989), troglitazone (n = 363) or lifestyle modification (n = 1,004) vs placebo (n = 1,000) for diabetes prevention in high-risk individuals. RESULTS At baseline, Ala12 carriers had larger waists (p < 0.001) and, in a subset, more subcutaneous adipose tissue (SAT; lumbar 2/3; p = 0.04) than Pro12 homozygotes. There was a genotype-by-intervention interaction on 1-year weight change (p = 0.01); in the placebo arm, Pro12 homozygotes gained weight and Ala12 carriers lost weight (p = 0.001). In the metformin and lifestyle arms, weight loss occurred across genotypes, but was greatest in Ala12 carriers (p < 0.05). Troglitazone treatment induced weight gain, which tended to be greater in Ala12 carriers (p = 0.08). In the placebo group, SAT (lumbar 2/3, lumbar 4/5) decreased in Ala12 allele carriers, but was unchanged in Pro12 homozygotes (p < or = 0.005). With metformin treatment, SAT decreased independently of genotype. In the lifestyle arm, SAT (lumbar 2/3) reductions occurred across genotypes, but were greater in Ala12 carriers (p = 0.03). A genotype-by-PUFA intake interaction on reduction in visceral fat (lumbar 4/5; p = 0.04) was also observed, which was most evident with metformin treatment (p < 0.001). CONCLUSIONS/INTERPRETATION Within the Diabetes Prevention Program, the Ala12 allele influences central obesity, an effect which may differ by treatment group and dietary PUFA intake (ClinicalTrials.gov ID no: NCT00004992).
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Affiliation(s)
- P W Franks
- Genetic Epidemiology and Clinical Research Group, Department of Public Health and Clinical Medicine, Section for Medicine, Umea University Hospital, Umea, Sweden
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25
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Christianson JL, Nicoloro S, Straubhaar J, Czech MP. Stearoyl-CoA desaturase 2 is required for peroxisome proliferator-activated receptor gamma expression and adipogenesis in cultured 3T3-L1 cells. J Biol Chem 2007; 283:2906-16. [PMID: 18032385 DOI: 10.1074/jbc.m705656200] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Based on recent evidence that fatty acid synthase and endogenously produced fatty acid derivatives are required for adipogenesis in 3T3-L1 adipocytes, we conducted a small interfering RNA-based screen to identify other fatty acid-metabolizing enzymes that may mediate this effect. Of 24 enzymes screened, stearoyl-CoA desaturase 2 (SCD2) was found to be uniquely and absolutely required for adipogenesis. Remarkably, SCD2 also controls the maintenance of adipocyte-specific gene expression in fully differentiated 3T3-L1 adipocytes, including the expression of SCD1. Despite the high sequence similarity between SCD2 and SCD1, silencing of SCD1 did not down-regulate 3T3-L1 cell differentiation or gene expression. SCD2 mRNA expression was also uniquely elevated 44-fold in adipose tissue upon feeding mice a high fat diet, whereas SCD1 showed little response. The inhibition of adipogenesis caused by SCD2 depletion was associated with a decrease in peroxisome proliferator-activated receptor gamma (PPARgamma) mRNA and protein, whereas in mature adipocytes loss of SCD2 diminished PPARgamma protein levels, with little change in mRNA levels. In the latter case, SCD2 depletion did not change the degradation rate of PPARgamma protein but decreased the metabolic labeling of PPARgamma protein using [(35)S]methionine/cysteine, indicating protein translation was decreased. This requirement of SCD2 for optimal protein synthesis in fully differentiated adipocytes was verified by polysome profile analysis, where a shift in the mRNA to monosomes was apparent in response to SCD2 silencing. These results reveal that SCD2 is required for the induction and maintenance of PPARgamma protein levels and adipogenesis in 3T3-L1 cells.
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Affiliation(s)
- Jennifer L Christianson
- Program in Molecular Medicine, University of Massachusetts Medical School, 373 Plantation Street, Worcester, MA 01605, USA
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26
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Curcumin inhibits connective tissue growth factor gene expression in activated hepatic stellate cells in vitro by blocking NF-kappaB and ERK signalling. Br J Pharmacol 2007; 153:557-67. [PMID: 17965732 DOI: 10.1038/sj.bjp.0707542] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND AND PURPOSE Gene expression of connective tissue growth factor (CTGF) is induced in activated hepatic stellate cells (HSC), the major effectors in hepatic fibrosis, and production of extracellular matrix (ECM) is consequently increased. We previously reported that curcumin, the yellow pigment in curry, suppressed ctgf expression, leading to decreased production of ECM by HSC. The purpose of this study is to evaluate signal transduction pathways involved in the curcumin suppression of ctgf expression in HSC. EXPERIMENTAL APPROACHES Transient transfection assays were performed to evaluate effects of activation of signalling pathways on the ctgf promoter activity. Real-time PCR and Western blotting analyses were conducted to determine expression of genes. RESULTS Suppression of ctgf expression by curcumin was dose-dependently reversed by lipopolysaccharide (LPS), an NF-kappaB activator. LPS increased the abundance of CTGF and type I collagen in HSC in vitro. Activation of NF-kappaB by dominant active IkappaB kinase (IKK), or inhibition of NF-kappaB by dominant negative IkappaBalpha, caused the stimulation, or suppression of the ctgf promoter activity, respectively. Curcumin suppressed gene expression of Toll-like receptor-4, leading to the inhibition of NF-kappaB. On the other hand, interruption of ERK signalling by inhibitors or dominant negative ERK, like curcumin, reduced NF-kappaB activity and in ctgf expression. In contrast, the stimulation of ERK signalling by constitutively active ERK prevented the inhibitory effects of curcumin. CONCLUSIONS AND IMPLICATIONS These results demonstrate that the interruption of NF-kappaB and ERK signalling by curcumin results in the suppression of ctgf expression in activated HSC in vitro.
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Sears DD, Hsiao A, Ofrecio JM, Chapman J, He W, Olefsky JM. Selective modulation of promoter recruitment and transcriptional activity of PPARgamma. Biochem Biophys Res Commun 2007; 364:515-21. [PMID: 17963725 DOI: 10.1016/j.bbrc.2007.10.057] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2007] [Accepted: 10/07/2007] [Indexed: 10/22/2022]
Abstract
Peroxisome proliferator-activated receptor gamma (PPARgamma) is a nuclear receptor regulated by the insulin-sensitizing thiazolidinediones (TZDs). We studied selective modulation of endogenous genes by PPARgamma ligands using microarray, RNA expression kinetics, and chromatin immunoprecipitation (ChIP) in 3T3-L1 adipocytes. We found over 300 genes that were significantly regulated the TZDs pioglitazone, rosiglitazone, and troglitazone. TZD-mediated expression profiles were unique but overlapping. Ninety-one genes were commonly regulated by all three ligands. TZD time course and dose-response studies revealed gene- and TZD-specific expression kinetics. PEPCK expression was induced rapidly but PDK4 expression was induced gradually. Troglitazone EC50 values for PEPCK, PDK4, and RGS2 regulation were greater than those for pioglitazone and rosiglitazone. TZDs differentially induced histone acetylation of and PPARgamma recruitment to target gene promoters. Selective modulation of PPARgamma by TZDs resulted in distinct expression profiles and transcription kinetics which may be due to differential promoter activation and chromatin remodeling of target genes.
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Affiliation(s)
- Dorothy D Sears
- Department of Medicine, University of California, San Diego, 9500 Gilman Drive, MC0673, La Jolla, CA 92093, USA.
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Zhou Y, Zheng S, Lin J, Zhang QJ, Chen A. The interruption of the PDGF and EGF signaling pathways by curcumin stimulates gene expression of PPARgamma in rat activated hepatic stellate cell in vitro. J Transl Med 2007; 87:488-98. [PMID: 17372590 DOI: 10.1038/labinvest.3700532] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Activation of hepatic stellate cells (HSC), the major effector in hepatic fibrogenesis, is coupled with sequential alterations in expression of genes, including the upregulation of platelet-derived growth factor-beta receptor (PDGF-betaR) and epidermal growth factor receptor (EGFR), as well as the down-regulation of the peroxisome proliferator-activated receptor-gamma (PPARgamma). However, the relationship among the alterations in expression of the genes and the activation of their signaling in activated HSC remains obscure. We recently showed that curcumin, the yellow pigment in curry, inhibited cell growth and induced gene expression of endogenous PPARgamma in activated HSC in vitro. The present study is to elucidate the underlying mechanisms, focusing on the impacts of PDGF and EGF signaling. It is hypothesized that the interruption of the PDGF and EGF signaling pathways by curcumin might stimulate gene expression of PPARgamma in activated HSC. Our results in this report indicate that the activation of PDGF or EGF signaling by exogenous PDGF or EGF inhibits PPARgamma gene expression in passaged HSC. Curcumin interrupts PDGF and EGF signaling demonstrated by inhibiting tyrosine phosphorylation of PDGF-betaR and EGFR and by reducing the levels of phosphorylated phosphatidylinositol-3 kinase (PI-3K/AKT), extracellular signal-regulated kinase (ERK) and the Jun N-terminal kinase (JNK). The blockade of PI-3K/AKT, ERK or JNK signaling negatively regulates PPARgamma gene expression in activated HSC, leading to the reduction in cell growth, including inducing cell arrest and apoptosis. Our results collectively demonstrate that the interruption of the PDGF and EGF signaling pathways by curcumin stimulates gene expression of PPARgamma in activated HSC. These results provide novel insights into the mechanisms of curcumin in the induction of PPARgamma gene expression in activated HSC.
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Affiliation(s)
- Yajun Zhou
- Department of Biochemistry, Nantong University, Nantong, China
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Guo W, Xie W, Han J. Modulation of adipocyte lipogenesis by octanoate: involvement of reactive oxygen species. Nutr Metab (Lond) 2006; 3:30. [PMID: 16872526 PMCID: PMC1550392 DOI: 10.1186/1743-7075-3-30] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2006] [Accepted: 07/27/2006] [Indexed: 11/19/2022] Open
Abstract
Background Octanoate is a medium-chain fatty acid (MCFA) that is rich in milk and tropical dietary lipids. It also accounts for 70% of the fatty acids in commercial medium chain triglycerides (MCT). Use of MCT for weight control tracks back to early 1950s and is highlighted by recent clinical trials. The molecular mechanisms of the weight reduction effect remain not completely understood. The findings of significant amounts of MCFA in adipose tissue in MCT-fed animals and humans suggest a direct influence of MCFA on fat cell functions. Methods 3T3-L1 adipocytes were treated with octanoate in a high glucose culture medium supplemented with 10% fetal bovine serum and 170 nM insulin. The effects on lipogenesis, fatty acid oxidation, cellular concentration of reactive oxygen species (ROS), and the expression and activity of peroxisome proliferator receptor gamma (PPARγ) and its associated lipogenic genes were assessed. In selected experiments, long-chain fatty acid oleate, PPARγ agonist troglitazone, and antioxidant N-acetylcysteine were used in parallel. Effects of insulin, L-carnitine, and etomoxir on β-oxidation were also measured. Results β-oxidation of octanoate was primarily independent of CPT-I. Treatment with octanoate was linked to an increase in ROS in adipocytes, a decrease in triglyceride synthesis, and reduction of lipogenic gene expression. Co-treatment with troglitazone, N-acetylcysteine, or over-expression of glutathione peroxidase largely reversed the effects of octanoate. Conclusion These findings suggest that octanoate-mediated inactivation of PPARγ might contribute to the down regulation of lipogenic genes in adipocytes, and ROS appears to be involved as a mediator in this process.
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Affiliation(s)
- Wen Guo
- Obesity Research Unit, Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA
| | - Weisheng Xie
- Obesity Research Unit, Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA
| | - Jianrong Han
- Obesity Research Unit, Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA
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Crandall DL, Quinet EM, El Ayachi S, Hreha AL, Leik CE, Savio DA, Juhan-Vague I, Alessi MC. Modulation of adipose tissue development by pharmacological inhibition of PAI-1. Arterioscler Thromb Vasc Biol 2006; 26:2209-15. [PMID: 16825598 DOI: 10.1161/01.atv.0000235605.51400.9d] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE The effect of a novel small molecule plasminogen activator inhibitor (PAI-1) inhibitor on adipose tissue physiology was investigated. METHODS AND RESULTS In human preadipocyte cultures, PAI-039 inhibited both basal and glucose-stimulated increases in active PAI-1 antigen, yet had no effect on PAI-1 mRNA, suggesting a direct inactivation of PAI-1. Differentiation of human preadipocytes to adipocytes was associated with leptin synthesis, which was significantly reduced in the presence of PAI-039, together with an atypical adipocyte morphology characterized by a reduction in the size and number of lipid containing vesicles. In a model of diet-induced obesity, pair-fed C57 Bl/6 mice administered PAI-039 in a high-fat diet exhibited a dose-dependent reduction in body weight, epididymal adipose tissue weight, adipocyte volume, and circulating plasma active PAI-1. Plasma glucose, triglycerides, and leptin were also significantly reduced in drug-treated mice, and concentrations of PAI-039 associated with these physiological effects were near the in vitro IC50 for the inhibition of PAI-1. CONCLUSIONS Our results indicate that a small molecule inactivator of PAI-1 can neutralize glucose-stimulated increases in PAI-1 in human preadipocyte cultures, reduce adipocyte differentiation, and prevent the development of diet-induced obesity. These data suggest the pharmacological inhibition of PAI-1 could be beneficial in diseases associated with expansion of adipose tissue mass.
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Affiliation(s)
- David L Crandall
- Cardiovascular and Metabolic Disease Research, Wyeth Research, N2265A, PO Box 42528, Philadelphia, PA 19101, USA.
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Nakano R, Kurosaki E, Yoshida S, Yokono M, Shimaya A, Maruyama T, Shibasaki M. Antagonism of peroxisome proliferator-activated receptor γ prevents high-fat diet-induced obesity in vivo. Biochem Pharmacol 2006; 72:42-52. [PMID: 16696951 DOI: 10.1016/j.bcp.2006.03.023] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Revised: 03/29/2006] [Accepted: 03/29/2006] [Indexed: 11/20/2022]
Abstract
Peroxisome proliferator-activated receptor gamma (PPARgamma) has been reported to play an important role to regulate adiposity and insulin sensitivity. It is not clear whether antagonism of PPARgamma using a synthetic ligand has significant effects on adipose tissue weight and glucose metabolism in vivo. The aim of this study is to examine the effects of a synthetic PPARgamma antagonist (GW9662) on adiposity and glycemic control in high-fat (HF) diet-fed mice. First the properties of GW9662 as a PPARgamma antagonist were estimated in vitro. GW9662 displaced [(3)H]rosiglitazone from PPARgamma with K(i) values of 13nM, indicating that the affinity of GW9662 for PPARgamma was higher than that of rosiglitazone (110nM). GW9662 had no effect on PPARgamma transactivation in cells expressing human PPARgamma. Treatment of 3T3-L1 preadipocytes with GW9662 did not increase aP2 expression or [(14)C]acetic acid uptake. GW9662 did not recruit transcriptional cofactors to PPARgamma. Limited trypsin digestion of the human PPARgamma/GW9662 complex showed patterns of digestion distinct from those of rosiglitazone. This suggests that the binding characteristics between GW9662 and PPARgamma are different from those of rosiglitazone. Treatment of HF diet-fed mice with GW9662 revealed that this compound prevented HF diet-induced obesity without affecting food intake. GW9662 suppressed any increase in the amount of visceral adipose tissue, but it did not change HF diet-induced glucose intolerance. These data indicate that antagonism of PPARgamma using a synthetic ligand suppresses the increased adiposity observed in HF diet-induced obesity, and that a PPARgamma antagonist could possibly be developed as an anti-obesity drug.
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Affiliation(s)
- Ryosuke Nakano
- Pharmacology Research Laboratories, Drug Discovery Research, Astellas Pharma Inc., 5-2-3 Toukoudai, Tsukuba-shi, Ibaraki 300-2698, Japan.
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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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Zheng S, Chen A. Curcumin suppresses the expression of extracellular matrix genes in activated hepatic stellate cells by inhibiting gene expression of connective tissue growth factor. Am J Physiol Gastrointest Liver Physiol 2006; 290:G883-93. [PMID: 16306131 DOI: 10.1152/ajpgi.00450.2005] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Upon liver injury, quiescent hepatic stellate cells (HSCs), the most relevant cell type for hepatic fibrogenesis, become active and overproduce extracellular matrix (ECM). Connective tissue growth factor (CTGF) promotes ECM production. Overexpression of CTGF during hepatic fibrogenesis is induced by transforming growth factor (TGF)-beta. We recently demonstrated that curcumin reduced cell growth and inhibited ECM gene expression in activated HSCs. Curcumin induced gene expression of peroxisome proliferator-activated receptor (PPAR)-gamma and stimulated its activity in activated HSCs, which was required for curcumin to suppress ECM gene expression, including alphaI(I)-collagen. The underlying mechanisms remain largely unknown. The aim of this study was to elucidate the mechanisms by which curcumin suppresses alphaI(I)-collagen gene expression in activated HSCs. We hypothesize that inhibition of alphaI(I)-collagen gene expression in HSCs by curcumin is mediated by suppressing CTGF gene expression through attenuating oxidative stress and interrupting TGF-beta signaling. The present report demonstrated that curcumin significantly reduced the abundance of CTGF in passaged HSCs and suppressed its gene expression. Exogenous CTGF dose dependently abrogated the inhibitory effect of curcumin. Activation of PPAR-gamma by curcumin resulted in the interruption of TGF-beta signaling by suppressing gene expression of TGF-beta receptors, leading to inhibition of CTGF gene expression. The phytochemical showed its potent antioxidant property by significantly increasing the level of total glutathione (GSH) and the ratio of GSH to GSSG in activated HSCs. De novo synthesis of cellular GSH was a prerequisite for curcumin to interrupt TGF-beta signaling and inhibited gene expression of CTGF and alphaI(I)-collagen in activated HSCs. Taken together, our results demonstrate that inhibition of alphaI(I)-collagen gene expression by curcumin in activated HSCs results from suppression of CTGF gene expression through increasing cellular GSH contents and interruption of TGF-beta signaling. These results provide novel insights into the mechanisms underlying inhibition of HSC activation by curcumin.
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Affiliation(s)
- Shizhong Zheng
- Department of Pathology, Louisiana State University Health Sciences Center-Shreveport, 1501 Kings Hwy., Shreveport, LA 71130, USA
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Lathion C, Michalik L, Wahli W. Physiological ligands of PPARs in inflammation and lipid homeostasis. ACTA ACUST UNITED AC 2006. [DOI: 10.2217/17460875.1.2.191] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Chui PC, Guan HP, Lehrke M, Lazar MA. PPARgamma regulates adipocyte cholesterol metabolism via oxidized LDL receptor 1. J Clin Invest 2005; 115:2244-56. [PMID: 16007265 PMCID: PMC1172230 DOI: 10.1172/jci24130] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2004] [Accepted: 05/17/2005] [Indexed: 01/21/2023] Open
Abstract
In addition to its role in energy storage, adipose tissue also accumulates cholesterol. Concentrations of cholesterol and triglycerides are strongly correlated in the adipocyte, but little is known about mechanisms regulating cholesterol metabolism in fat cells. Here we report that antidiabetic thiazolidinediones (TZDs) and other ligands for the nuclear receptor PPARgamma dramatically upregulate oxidized LDL receptor 1 (OLR1) in adipocytes by facilitating the exchange of coactivators for corepressors on the OLR1 gene in cultured mouse adipocytes. TZDs markedly stimulate the uptake of oxidized LDL (oxLDL) into adipocytes, and this requires OLR1. Increased OLR1 expression, resulting either from TZD treatment or adenoviral gene delivery, significantly augments adipocyte cholesterol content and enhances fatty acid uptake. OLR1 expression in white adipose tissue is increased in obesity and is further induced by PPARgamma ligand treatment in vivo. Serum oxLDL levels are decreased in both lean and obese diabetic animals treated with TZDs. These data identify OLR1 as a novel PPARgamma target gene in adipocytes. While the physiological role of adipose tissue in cholesterol and oxLDL metabolism remains to be established, the induction of OLR1 is a potential means by which PPARgamma ligands regulate lipid metabolism and insulin sensitivity in adipocytes.
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Affiliation(s)
- Patricia C Chui
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, and The Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6149, USA
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36
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Zheng S, Chen A. Activation of PPARgamma is required for curcumin to induce apoptosis and to inhibit the expression of extracellular matrix genes in hepatic stellate cells in vitro. Biochem J 2005; 384:149-57. [PMID: 15320868 PMCID: PMC1134098 DOI: 10.1042/bj20040928] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
During liver fibrogenesis, quiescent HSC (hepatic stellate cells) become active, a transformation that is associated with enhanced cell proliferation and overproduction of ECM (extracellular matrix). Inhibition of cell proliferation and induction of apoptosis are potential strategies to block the activation of HSC for the prevention and treatment of liver fibrosis. Levels of PPARgamma (peroxisome proliferator-activated receptor gamma) are dramatically diminished in parallel with HSC activation. Stimulation of PPARgamma by its agonists inhibits HSC activation in vitro and in vivo. We demonstrated recently that curcumin, the yellow pigment in curry, inhibited HSC activation in vitro, reducing cell proliferation, inducing apoptosis and inhibiting ECM gene expression. Further studies indicated that curcumin induced the gene expression of PPARgamma and stimulated its activity in activated HSC in vitro, which was required for curcumin to inhibit HSC proliferation. The aims of the present study were to evaluate the roles of PPARgamma activation in the induction of apoptosis and suppression of ECM gene expression by curcumin in activated HSC, and to elucidate the underlying mechanisms. Our results demonstrated that blocking PPARgamma activation abrogated the effects of curcumin on the induction of apoptosis and inhibition of the expression of ECM genes in activated HSC in vitro. Further experiments demonstrated that curcumin suppressed the gene expression of TGF-beta (transforming growth factor-beta) receptors and interrupted the TGF-beta signalling pathway in activated HSC, which was mediated by PPARgamma activation. Taken together, our results demonstrate that curcumin stimulated PPARgamma activity in activated HSC in vitro, which was required for curcumin to reduce cell proliferation, induce apoptosis and suppress ECM gene expression. These results provide novel insight into the mechanisms responsible for the inhibition of HSC activation by curcumin. The characteristics of curcumin, which has no adverse health effects, make it a potential candidate for prevention and treatment of hepatic fibrosis.
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Affiliation(s)
- Shizhong Zheng
- *Department of Pathology, Louisiana State University Health Sciences Center in Shreveport, Shreveport, LA 71130, U.S.A
- †Department of Pharmacology, Nanjing Medical University, Nanjing, China
| | - Anping Chen
- *Department of Pathology, Louisiana State University Health Sciences Center in Shreveport, Shreveport, LA 71130, U.S.A
- ‡Department of Cellular Biology & Anatomy, Louisiana State University Health Sciences Center in Shreveport, Shreveport, LA 71130, U.S.A
- To whom correspondence should be addressed (email )
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37
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Bartalena L, Marcocci C, Tanda ML, Piantanida E, Lai A, Marinò M, Pinchera A. An update on medical management of Graves' ophthalmopathy. J Endocrinol Invest 2005; 28:469-78. [PMID: 16075933 DOI: 10.1007/bf03347230] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Graves' ophthalmopathy (GO), the most frequent extrathyroidal manifestation of Graves' disease, is a disorder of autoimmune origin, the pathogenic mechanisms of which are still incompletely understood. Although GO is severe in only 3-5% of affected individuals, quality of life is severely impaired even in patients with mild GO. Management of severe GO can be either medical or surgical (orbital decompression, eye muscle or lid surgery). Medical management relies on the use of high-dose systemic glucocorticoids or orbital radiotherapy, either alone or in combination. Studies carried out in the last 5 yr have shown that glucocorticoids are more effective through the i.v. route than through the oral route. However, particular attention should be paid to possible liver toxicity of i.v. glucocorticoids. Recent randomized clinical trials have, with one exception, confirmed that orbital radiotherapy is an effective and safe therapeutic procedure for GO. At variance with previous encouraging data, recent randomized clinical trials have shown that currently available SS analogs are not very effective in the management of GO. Antioxidants might have a role, at least in mild forms of GO. Particular attention should be paid to correction of risk factors (cigarette smoking, thyroid dysfunction, radioiodine therapy) involved in GO progression.
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Affiliation(s)
- L Bartalena
- Department of Clinical Medicine, University of Insubria, Varese, Italy.
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38
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Chen A, Xu J. Activation of PPAR{gamma} by curcumin inhibits Moser cell growth and mediates suppression of gene expression of cyclin D1 and EGFR. Am J Physiol Gastrointest Liver Physiol 2005; 288:G447-56. [PMID: 15486348 DOI: 10.1152/ajpgi.00209.2004] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Colorectal cancer is a leading cause of cancer-related morbidity and mortality in the United States. Curcumin, the yellow pigment in turmeric, possesses inhibitory effects on growth of a variety of tumor cells by reducing cell proliferation and inducing apoptosis. Effects of the peroxisome proliferator-activated receptor-gamma (PPARgamma) on stimulating cell differentiation and on inducing cell cycle arrest have attracted attention from the perspective of treatment and prevention of cancer. The aim of this study was to elucidate the mechanisms by which curcumin inhibits colon cancer cell growth. In the present report, we observed that curcumin, in a dose-dependent manner, inhibited the growth of Moser cells, a human colon cancer-derived cell line, and stimulated the trans-activating activity of PPARgamma. Further studies demonstrated that activation of PPARgamma was required for curcumin to inhibit Moser cell growth. Activation of PPARgamma mediated curcumin suppression of the expression of cyclin D1, a critical protein in the cell cycle, in Moser cells. In addition, curcumin blocked EGF signaling by inhibiting EGF receptor (EGFR) tyrosine phosphorylation and suppressing the gene expression of EGFR mediated by activation of PPARgamma. In addition to curcumin reduction of the level of phosphorylated PPARgamma, inhibition of cyclin D1 expression played a major and significant role in curcumin stimulation of PPARgamma activity in Moser cells. Taken together, our results demonstrated for the first time that curcumin activation of PPARgamma inhibited Moser cell growth and mediated the suppression of the gene expression of cyclin D1 and EGFR. These results provided a novel insight into the roles and mechanisms of curcumin in inhibition of colon cancer cell growth and potential therapeutic strategies for treatment of colon cancer.
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Affiliation(s)
- Anping Chen
- Department of Pathology, Louisiana State University, Health Sciences Center in Shreveport, 1501 Kings Hwy, Shreveport, LA 71130, USA.
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39
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Zeyda M, Säemann MD, Stuhlmeier KM, Mascher DG, Nowotny PN, Zlabinger GJ, Waldhäusl W, Stulnig TM. Polyunsaturated fatty acids block dendritic cell activation and function independently of NF-kappaB activation. J Biol Chem 2005; 280:14293-301. [PMID: 15684433 DOI: 10.1074/jbc.m410000200] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Polyunsaturated fatty acids (PUFAs) modulate immune responses leading to clinically significant beneficial effects in a variety of inflammatory disorders. PUFA effects on T cells have been extensively studied, but their influence on human dendritic cells (DCs), which are the most potent antigen-presenting cells and play a key role in initiating immune responses, has not been elucidated so far. Here we show that PUFAs of the n-3 and n-6 series (arachidonic and eicosapentaenoic acid) affect human monocyte-derived DC differentiation and inhibit their activation by LPS, resulting in altered DC surface molecule expression and diminished cytokine secretion. Furthermore, the potency to stimulate T cells was markedly inhibited in PUFA-treated DCs. The PUFA-mediated block in LPS-induced DC activation is reflected by diminished TNF-alpha, IL-12p40, CD40, and COX-2 mRNA levels. Strikingly, typical LPS-induced signaling events such as degradation of IkappaB and activation of NF-kappaB were not affected by PUFAs, even though DC membrane lipid composition was markedly altered. Arachidonic and eicosapentaenoic acid both altered DC prostaglandin production, but inhibitors of cyclooxygenases and lipoxygenases did not abolish PUFA effects, indicating that the observed PUFA actions on DCs were independent of autoregulation via eicosanoids. These data demonstrate a unique interference with DC activation and function that could significantly contribute to the well known anti-inflammatory effects of PUFAs.
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Affiliation(s)
- Maximilian Zeyda
- Clinical Divisions of Endocrinology and Metabolism, Medical University of Vienna, Währinger Gürtel 18-20, A-1090 Vienna, Austria
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Guan HP, Ishizuka T, Chui PC, Lehrke M, Lazar MA. Corepressors selectively control the transcriptional activity of PPARgamma in adipocytes. Genes Dev 2005; 19:453-61. [PMID: 15681609 PMCID: PMC548946 DOI: 10.1101/gad.1263305] [Citation(s) in RCA: 238] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Peroxisome proliferator-activated receptor gamma (PPARgamma) is the master regulator of adipogenesis as well as the target of thiazolidinedione (TZD) antidiabetic drugs. Many PPARgamma target genes are induced during adipogenesis, but others, such as glycerol kinase (GyK), are expressed at low levels in adipocytes and dramatically up-regulated by TZDs. Here, we have explored the mechanism whereby an exogenous PPARgamma ligand is selectively required for adipocyte gene expression. The GyK gene contains a functional PPARgamma-response element to which endogenous PPARgamma is recruited in adipocytes. However, unlike the classic PPARgamma-target gene aP2, which is constitutively associated with coactivators, the GyK gene is targeted by nuclear receptor corepressors in adipocytes. TZDs trigger the dismissal of corepressor histone deacetylase (HDAC) complexes and the recruitment of coactivators to the GyK gene. TZDs also induce PPARgamma-Coactivator 1alpha (PGC-1alpha), whose recruitment to the GyK gene is sufficient to release the corepressors. Thus, selective modulation of adipocyte PPARgamma target genes by TZDs involves the dissociation of corepressors by direct and indirect mechanisms.
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Affiliation(s)
- Hong-Ping Guan
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, The Penn Diabetes Center, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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Knouff C, Auwerx J. Peroxisome proliferator-activated receptor-gamma calls for activation in moderation: lessons from genetics and pharmacology. Endocr Rev 2004; 25:899-918. [PMID: 15583022 DOI: 10.1210/er.2003-0036] [Citation(s) in RCA: 220] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The peroxisome proliferator-activated receptor gamma (PPARgamma) is a prototypical member of the nuclear receptor superfamily and integrates the control of energy, lipid, and glucose homeostasis. PPARgamma can bind a variety of small lipophilic compounds derived from metabolism and nutrition. These ligands, in turn, determine cofactor recruitment to PPARgamma, regulating the transcription of genes in a variety of metabolic pathways. PPARgamma is the main target of the thiazolidinedione class of insulin-sensitizing drugs, which are currently a mainstay of therapy for type 2 diabetes. However, this therapy has a number of side effects. Here, we review the clinical consequences of PPARgamma polymorphisms in humans, as well as several studies in mice using general or tissue-specific knockout techniques. We also discuss the recent pharmacological literature describing a variety of new PPARgamma partial agonists and antagonists, as well as pan-PPAR agonists. The results of these studies have added to the understanding of PPARgamma function, allowing us to hypothesize a general mechanism of PPARgamma action and speculate on future trends in the use of PPARgamma as a target in the treatment of type II diabetes.
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Affiliation(s)
- Chris Knouff
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique/Institut National de la Santé et de la Recherche Médicale/Université Louis Pasteur, Illkirch, France
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Tzameli I, Fang H, Ollero M, Shi H, Hamm JK, Kievit P, Hollenberg AN, Flier JS. Regulated Production of a Peroxisome Proliferator-activated Receptor-γ Ligand during an Early Phase of Adipocyte Differentiation in 3T3-L1 Adipocytes. J Biol Chem 2004; 279:36093-102. [PMID: 15190061 DOI: 10.1074/jbc.m405346200] [Citation(s) in RCA: 145] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Peroxisome proliferator-activated receptor-gamma (PPARgamma) is a nuclear hormone receptor that is critical for adipogenesis and insulin sensitivity. Ligands for PPARgamma include some polyunsaturated fatty acids and prostanoids and the synthetic high affinity antidiabetic agents thiazolidinediones. However, the identity of a biologically relevant endogenous PPARgamma ligand is unknown, and limited insight exists into the factors that may regulate production of endogenous PPARgamma ligands during adipocyte development. To address this question, we created a line of 3T3-L1 preadipocytes that carry a beta-galactosidase-based PPARgamma ligand-sensing vector system. In this system, induction of adipogenesis resulted in elevated beta-galactosidase activity that signifies activation of PPARgamma via its ligand-binding domain (LBD) and suggests generation and/or accumulation of a ligand moiety. The putative endogenous ligand appeared early in adipogenesis in response to increases in cAMP, accumulated in the medium, and dissipated later in adipogenesis. Organically extracted and high pressure liquid chromatography-fractionated conditioned media from differentiating cells, but not from mature adipocytes, were enriched in this activity. One or more components within the organic extract activated PPARgamma through interaction with its LBD, induced lipid accumulation in 3T3-L1 cells as efficiently as the differentiation mixture, and competed for binding of rosiglitazone to the LBD of PPARgamma. The active species appears to be different from other PPARgamma ligands identified previously. Our findings suggest that a novel biologically relevant PPARgamma ligand is transiently produced in 3T3-L1 cells during adipogenesis.
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Affiliation(s)
- Iphigenia Tzameli
- Division of Endocrinology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
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Granlund L, Juvet LK, Pedersen JI, Nebb HI. Trans10, cis12-conjugated linoleic acid prevents triacylglycerol accumulation in adipocytes by acting as a PPARgamma modulator. J Lipid Res 2003; 44:1441-52. [PMID: 12754280 DOI: 10.1194/jlr.m300120-jlr200] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
A group of polyunsaturated fatty acids called conjugated linoleic acids (CLAs) are found in ruminant products, where the most common isomers are cis9, trans11 (c 9,t11) and trans10, cis12 (t10,c12) CLA. A crude mixture of these isomers has been shown in animal studies to alter body composition by a reduction in body fat mass as well as an increase in lean body mass, with the t10,c12 isomer having the most pronounced effect. The objective of this study was to establish the molecular mechanisms by which t10,c12 CLA affects lipid accumulation in adipocytes. We have shown that t10,c12 CLA prevents lipid accumulation in human and mouse adipocytes at concentrations as low as 5 microM and 25 microM, respectively. t10,c12 CLA fails to activate peroxisome proliferator-activated receptor gamma (PPARgamma) but selectively inhibits thiazolidinedione-induced PPARgamma activation in 3T3-L1 adipocytes. Treatment of mature adipocytes with t10,c12 CLA alone or in combination with Darglitazone down-regulates the mRNA expression of PPARgamma as well as its target genes, fatty acid binding protein (aP2) and liver X receptor alpha (LXRalpha). Taken together, our results suggest that the trans10, cis12 CLA isomer prevents lipid accumulation in adipocytes by acting as a PPARgamma modulator.
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Affiliation(s)
- Linda Granlund
- Institute for Nutrition Research, University of Oslo, N-0316 Oslo, Norway
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Xu J, Fu Y, Chen A. Activation of peroxisome proliferator-activated receptor-gamma contributes to the inhibitory effects of curcumin on rat hepatic stellate cell growth. Am J Physiol Gastrointest Liver Physiol 2003; 285:G20-30. [PMID: 12660143 DOI: 10.1152/ajpgi.00474.2002] [Citation(s) in RCA: 179] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Hepatic fibrogenesis occurs as a wound-healing process after many forms of chronic liver injury. Hepatic fibrosis ultimately leads to cirrhosis if not treated effectively. During liver injury, quiescent hepatic stellate cells (HSC), the most relevant cell type, become active and proliferative. Oxidative stress is a major and critical factor for HSC activation. Activation of peroxisome proliferator-activated receptor-gamma (PPAR-gamma) inhibits the proliferation of nonadipocytes. The level of PPAR-gamma is dramatically diminished along with activation of HSC. Curcumin, the yellow pigment in curry, is a potent antioxidant. The aims of this study were to evaluate the effect of curcumin on HSC proliferation and to begin elucidating underlying mechanisms. It was hypothesized that curcumin might inhibit the proliferation of activated HSC by inducing PPAR-gamma gene expression and reviving PPAR-gamma activation. Our results indicated that curcumin significantly inhibited the proliferation of activated HSC and induced apoptosis in vitro. We demonstrated, for the first time, that curcumin dramatically induced the gene expression of PPAR-gamma and activated PPAR-gamma in activated HSC. Blocking its trans-activating activity by a PPAR-gamma antagonist markedly abrogated the effects of curcumin on inhibition of cell proliferation. Our results provide a novel insight into mechanisms underlying the inhibition of activated HSC growth by curcumin. The characteristics of curcumin, including antioxidant potential, reduction of activated HSC growth, and no adverse health effects, make it a potential antifibrotic candidate for prevention and treatment of hepatic fibrosis.
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Affiliation(s)
- Jianye Xu
- Dept. of Pathology, Louisiana State University Health Sciences Center, 1501 Kings Highway, Shreveport, LA 71130, USA
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45
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Doggrell S. Do peroxisome proliferation receptor-gamma antagonists have clinical potential as combined antiobesity and antidiabetic drugs? Expert Opin Investig Drugs 2003; 12:713-6. [PMID: 12665425 DOI: 10.1517/13543784.12.4.713] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
There is genetic evidence that reducing the activity of peroxisome proliferation receptor-gamma (PPAR-gamma) may increase insulin sensitivity. SR-202 is a selective antagonist at PPAR-gamma, which inhibits the adipocyte differentiation normally seen with the PPAR-gamma agonist rosiglitazone. SR-202 also reduces the ability of young mice to put on weight and accumulate fat. The levels of circulating TNF-alpha correlates with body fat stores and/or hyperinsulinaemia. SR-202- treated wild-type mice have reduced TNF-alpha levels. When wild-type mice are fed a high-fat diet, the plasma levels of TNF-alpha are raised, and SR-202 treatment protects against this rise. Feeding mice with a high-fat diet induced insulin resistance measured as increased plasma levels of glucose, insulin and free fatty acids, and SR-202 protected against these changes. The ob/ob mouse is diabetic at 8 weeks and plasma glucose and insulin levels continue to rise over the next 3 weeks, and treatment with SR-202 prevents these increases. The development of PPAR-gamma antagonists should continue as the results to date suggest that they have clinical potential for the treatment of diabetes Type 2 and obesity.
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Affiliation(s)
- Sheila Doggrell
- School of Biomedical Sciences, The University of Queensland, QLD 4072, Australia.
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46
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Larsen TM, Toubro S, Astrup A. PPARgamma agonists in the treatment of type II diabetes: is increased fatness commensurate with long-term efficacy? Int J Obes (Lond) 2003; 27:147-61. [PMID: 12586994 DOI: 10.1038/sj.ijo.802223] [Citation(s) in RCA: 204] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The nuclear hormone receptor peroxisome proliferator-activated receptor gamma (PPARgamma) is a member of the PPAR family. The endogenous activators of all members of the PPAR family are a variety of fatty acids, which suggests that the PPARs are highly involved in lipid metabolism. In the present paper, the current understanding of the involvement of PPARgamma in adipocyte proliferation and adipose tissue formation is extensively reviewed, and it is stressed that PPARgamma seems to be a major regulator in the differentiation of adipocytes. Thiazoledinediones (TZDs) are a group of PPARgamma-agonists used in the treatment of type 2 diabetes (T2D) since 1997. They are characterized by their ability to decrease insulin resistance, and have been suggested to slow down the progression of insulin resistance. Treatment with TZD requires several weeks of treatment to decrease plasma glucose levels, but in addition they markedly decrease plasma triglycerides and free fatty acids. A major drawback of treatment with TZD is body fat gain, but some evidence suggests that the fat is redistributed in a favourable direction, that is, from visceral to subcutaneous depots. However, the effect of long-term treatment on weight gain following TZD treatment is unknown, and it may be questioned whether the use of these 'adipogenic compounds' is appropriate, considering that excess body fat is almost a prerequisite for the development of type 2 diabetes.
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Affiliation(s)
- T M Larsen
- Research Department of Human Nutrition, The Royal Veterinary and Agricultural University, Copenhagen, Denmark.
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47
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Jowsey IR, Murdock PR, Moore GBT, Murphy GJ, Smith SA, Hayes JD. Prostaglandin D2 synthase enzymes and PPARgamma are co-expressed in mouse 3T3-L1 adipocytes and human tissues. Prostaglandins Other Lipid Mediat 2003; 70:267-84. [PMID: 12611492 DOI: 10.1016/s0090-6980(02)00134-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Peroxisome proliferator-activated receptor gamma (PPARgamma) is a critical regulator of adipocyte differentiation. Whilst 15-deoxy-delta(12,14)-prostaglandin J2 (15-d-PGJ2) has been identified as a putative endogenous ligand for this transcription factor, it is unclear whether the enzymes necessary for 15-d-PGJ2 biosynthesis are co-expressed with PPARgamma. Prostaglandin D2 synthase (PGDS) enzymes represent the terminal enzymatic components responsible for 15-d-PGJ2 production. Both glutathione (GSH)-dependent and GSH-independent PGDS isoenzymes exist. We have, therefore, examined the expression of PGDS isoenzymes in mouse 3T3-L1 adipocytes, and various human tissues. The GSH-independent PGDS was found to be expressed in 3T3-L1 cells both before and after their differentiation into adipocytes. By contrast, we were unable to detect expression of the GSH-dependent PGDS at any stage during the adipose conversion of 3T3-L1 cells. Quantitative analysis of mRNA levels for PPARgamma and each PGDS isoenzyme revealed their co-expression in a number of human tissues and cell types, including adipose tissue, placenta, prostate, and macrophages. These data reveal the potential for de novo 15-d-PGJ2 synthesis in the context of PPARgamma expression, suggesting that this prostaglandin may contribute to PPARgamma signalling in vivo.
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Affiliation(s)
- Ian R Jowsey
- Biomedical Research Centre, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, Scotland, UK.
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48
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Guan HP, Li Y, Jensen MV, Newgard CB, Steppan CM, Lazar MA. A futile metabolic cycle activated in adipocytes by antidiabetic agents. Nat Med 2002; 8:1122-8. [PMID: 12357248 DOI: 10.1038/nm780] [Citation(s) in RCA: 285] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2002] [Accepted: 08/28/2002] [Indexed: 12/18/2022]
Abstract
Thiazolidinediones (TZDs) are effective therapies for type 2 diabetes, which has reached epidemic proportions in industrialized societies. TZD treatment reduces circulating free fatty acids (FFAs), which oppose insulin actions in skeletal muscle and other insulin target tissues. Here we report that TZDs, acting as ligands for the nuclear receptor peroxisome proliferator-activated receptor (PPAR)-gamma, markedly induce adipocyte glycerol kinase (GyK) gene expression. This is surprising, as standard textbooks indicate that adipocytes lack GyK and thereby avoid futile cycles of triglyceride breakdown and resynthesis from glycerol and FFAs. By inducing GyK, TZDs markedly stimulate glycerol incorporation into triglyceride and reduce FFA secretion from adipocytes. The 'futile' fuel cycle resulting from expression of GyK in adipocytes is thus a novel mechanism contributing to reduced FFA levels and perhaps insulin sensitization by antidiabetic therapies.
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Affiliation(s)
- Hong-Ping Guan
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine and The Penn Diabetes Center, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
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49
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Tamori Y, Masugi J, Nishino N, Kasuga M. Role of peroxisome proliferator-activated receptor-gamma in maintenance of the characteristics of mature 3T3-L1 adipocytes. Diabetes 2002; 51:2045-55. [PMID: 12086932 DOI: 10.2337/diabetes.51.7.2045] [Citation(s) in RCA: 217] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Peroxisome proliferator-activated receptor (PPAR)-gamma plays an important role in adipogenesis. However, the functions of PPAR-gamma in differentiated adipocytes have remained unclear. The role of PPAR-gamma in mature 3T3-L1 adipocytes was therefore investigated by overexpression of a dominant negative mutant of this protein (PPAR-gamma-DeltaC) that lacks the 16 COOH-terminal amino acids and that has been shown to prevent the thiazolidinedione-induced differentiation of 3T3-L1 cells into adipocytes. Overexpression of PPAR-gamma-DeltaC in mature 3T3-L1 adipocytes by adenovirus gene transfer resulted in a decrease in both cell size and intracellular triglyceride content, an increase in the extent of lipolysis, and a reduction in the rate of free fatty acid uptake. Furthermore, overexpression of this mutant reduced the abundance of mRNAs for several key enzymes that contribute to triglyceride and free fatty acid metabolism as well as the amounts of GLUT4, insulin receptor, insulin receptor substrate (IRS), and C/EBPalpha mRNAs. It also reduced both the concentration of IRS2 and the insulin-stimulated glucose uptake. These results suggest that PPAR-gamma plays an important role in mature 3T3-L1 adipocytes at least in part by maintaining the expression of genes that confer the characteristics of mature adipocytes.
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Affiliation(s)
- Yoshikazu Tamori
- Division of Diabetes, Digestive, and Kidney Diseases, Department of Clinical Molecular Medicine, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan.
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50
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Lee G, Elwood F, McNally J, Weiszmann J, Lindstrom M, Amaral K, Nakamura M, Miao S, Cao P, Learned RM, Chen JL, Li Y. T0070907, a selective ligand for peroxisome proliferator-activated receptor gamma, functions as an antagonist of biochemical and cellular activities. J Biol Chem 2002; 277:19649-57. [PMID: 11877444 DOI: 10.1074/jbc.m200743200] [Citation(s) in RCA: 232] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The nuclear hormone receptor peroxisome proliferator-activated receptor gamma (PPARgamma (NR1C3)) plays a central role in adipogenesis and is the molecular target for the thiazolidinedione (TZD) class of antidiabetic drugs. In a search for novel non-TZD ligands for PPARgamma, T0070907 was identified as a potent and selective PPARgamma antagonist. With an apparent binding affinity (concentration at 50% inhibition of [(3)H]rosiglitazone binding or IC(50)) of 1 nm, T0070907 covalently modifies PPARgamma on cysteine 313 in helix 3 of human PPARgamma2. T0070907 blocked PPARgamma function in both cell-based reporter gene and adipocyte differentiation assays. Consistent with its role as an antagonist of PPARgamma, T0070907 blocked agonist-induced recruitment of coactivator-derived peptides to PPARgamma in a homogeneous time-resolved fluorescence-based assay and promoted recruitment of the transcriptional corepressor NCoR to PPARgamma in both glutathione S-transferase pull-down assays and a PPARgamma/retinoid X receptor (RXR) alpha-dependent gel shift assay. Studies with mutant receptors suggest that T0070907 modulates the interaction of PPARgamma with these cofactor proteins by affecting the conformation of helix 12 of the PPARgamma ligand-binding domain. Interestingly, whereas the T0070907-induced NCoR recruitment to PPARgamma/RXRalpha heterodimer can be almost completely reversed by the simultaneous treatment with RXRalpha agonist LGD1069, T0070907 treatment has only modest effects on LGD1069-induced coactivator recruitment to the PPARgamma/RXRalpha heterodimer. These results suggest that the activity of PPARgamma antagonists can be modulated by the availability and concentration of RXR agonists. T0070907 is a novel tool for the study of PPARgamma/RXRalpha heterodimer function.
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MESH Headings
- 3T3 Cells
- Adipocytes/cytology
- Adipocytes/metabolism
- Allosteric Site
- Amino Acid Sequence
- Animals
- Anticarcinogenic Agents/pharmacology
- Benzamides/chemistry
- Benzamides/pharmacology
- Bexarotene
- Cell Differentiation
- Cell Line
- Cysteine/chemistry
- Dimerization
- Dose-Response Relationship, Drug
- Glutathione Transferase/metabolism
- Humans
- Ligands
- Mice
- Molecular Sequence Data
- Mutation
- Peptides/chemistry
- Plasmids/metabolism
- Protein Binding
- Protein Conformation
- Protein Structure, Tertiary
- Pyridines/chemistry
- Pyridines/pharmacology
- Receptors, Cytoplasmic and Nuclear/antagonists & inhibitors
- Receptors, Cytoplasmic and Nuclear/chemistry
- Receptors, Cytoplasmic and Nuclear/metabolism
- Receptors, Retinoic Acid/metabolism
- Recombinant Fusion Proteins/metabolism
- Retinoid X Receptors
- Spectrometry, Fluorescence
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
- Tetrahydronaphthalenes/pharmacology
- Time Factors
- Transcription Factors/antagonists & inhibitors
- Transcription Factors/chemistry
- Transcription Factors/metabolism
- Transcription, Genetic
- Transfection
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Affiliation(s)
- Gary Lee
- Tularik Inc., South San Francisco, California 94080, USA
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