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Buchner DA, Charrier A, Srinivasan E, Wang L, Paulsen MT, Ljungman M, Bridges D, Saltiel AR. Zinc finger protein 407 (ZFP407) regulates insulin-stimulated glucose uptake and glucose transporter 4 (Glut4) mRNA. J Biol Chem 2015; 290:6376-86. [PMID: 25596527 DOI: 10.1074/jbc.m114.623736] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The glucose transporter GLUT4 facilitates insulin-stimulated glucose uptake in peripheral tissues including adipose, muscle, and heart. GLUT4 function is impaired in obesity and type 2 diabetes leading to hyperglycemia and an increased risk of cardiovascular disease and neuropathy. To better understand the regulation of GLUT4 function, a targeted siRNA screen was performed and led to the discovery that ZFP407 regulates insulin-stimulated glucose uptake in adipocytes. The decrease in insulin-stimulated glucose uptake due to ZFP407 deficiency was attributed to a reduction in GLUT4 mRNA and protein levels. The decrease in GLUT4 was due to both decreased transcription of Glut4 mRNA and decreased efficiency of Glut4 pre-mRNA splicing. Interestingly, ZFP407 coordinately regulated this decrease in transcription with an increase in the stability of Glut4 mRNA, resulting in opposing effects on steady-state Glut4 mRNA levels. More broadly, transcriptome analysis revealed that ZFP407 regulates many peroxisome proliferator-activated receptor (PPAR) γ target genes beyond Glut4. ZFP407 was required for the PPARγ agonist rosiglitazone to increase Glut4 expression, but was not sufficient to increase expression of a PPARγ target gene reporter construct. However, ZFP407 and PPARγ co-overexpression synergistically activated a PPARγ reporter construct beyond the level of PPARγ alone. Thus, ZFP407 may represent a new modulator of the PPARγ signaling pathway.
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Affiliation(s)
- David A Buchner
- From the Departments of Genetics and Genome Sciences and Biological Chemistry, Case Western Reserve University, Cleveland, Ohio 44106,
| | | | - Ethan Srinivasan
- the Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109
| | - Li Wang
- From the Departments of Genetics and Genome Sciences and
| | - Michelle T Paulsen
- the Department of Oncology, Division of Radiation and Cancer Biology, University of Michigan Cancer Center, Ann Arbor, Michigan 48109
| | - Mats Ljungman
- the Department of Oncology, Division of Radiation and Cancer Biology, University of Michigan Cancer Center, Ann Arbor, Michigan 48109
| | - Dave Bridges
- the Department of Physiology, University of Tennessee Health Sciences Center, Memphis, Tennessee 38163, and the Children's Foundation Research Institute, Le Bonheur Children's Hospital, Department of Pediatrics, University of Tennessee Health Sciences Center, Memphis, Tennessee 38103
| | - Alan R Saltiel
- the Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109,
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2
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Liu YY, Ayers S, Milanesi A, Teng X, Rabi S, Akiba Y, Brent GA. Thyroid hormone receptor sumoylation is required for preadipocyte differentiation and proliferation. J Biol Chem 2015; 290:7402-15. [PMID: 25572392 DOI: 10.1074/jbc.m114.600312] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Thyroid hormone and thyroid hormone receptor (TR) play an essential role in metabolic regulation. However, the role of TR in adipogenesis has not been established. We reported previously that TR sumoylation is essential for TR-mediated gene regulation and that mutation of either of the two sites in TRα or any of the three sites in TRβ reduces TR sumoylation. Here, we transfected TR sumoylation site mutants into human primary preadiocytes and the mouse 3T3L1 preadipocyte cell line to determine the role of TR sumoylation in adipogenesis. Reduced sumoylation of TRα or TRβ resulted in fewer and smaller lipid droplets and reduced proliferation of preadipocytes. TR sumoylation mutations, compared with wild-type TR, results in reduced C/EBP expression and reduced PPARγ2 mRNA and protein levels. TR sumoylation mutants recruited NCoR and disrupted PPARγ-mediated perilipin1 (Plin1) gene expression, associated with impaired lipid droplet formation. Expression of NCoRΔID, a mutant NCoR lacking the TR interaction domain, partially "rescued" the delayed adipogenesis and restored Plin1 gene expression and adipogenesis. TR sumoylation site mutants impaired Wnt/β-catenin signaling pathways and the proliferation of primary human preadipocytes. Expression of the TRβ K146Q sumoylation site mutant down-regulated the essential genes required for canonical Wnt signal-mediated proliferation, including Wnt ligands, Fzds, β-catenin, LEF1, and CCND1. Additionally, the TRβ K146Q mutant enhanced the canonical Wnt signaling inhibitor Dickkopf-related protein 1 (DKK1). Our data demonstrate that TR sumoylation is required for activation of the Wnt canonical signaling pathway during preadipocyte proliferation and enhances the PPARγ signaling that promotes differentiation.
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Affiliation(s)
- Yan-Yun Liu
- From the Molecular Endocrinology Laboratory, Veterans Affairs Greater Los Angeles Healthcare System and Departments of Medicine and Physiology, David Geffen School of Medicine at UCLA, Los Angeles, California 90073,
| | - Stephen Ayers
- the Genomic Medicine Program, Methodist Hospital Research Institute, Houston, Texas 77030, and
| | - Anna Milanesi
- From the Molecular Endocrinology Laboratory, Veterans Affairs Greater Los Angeles Healthcare System and Departments of Medicine and Physiology, David Geffen School of Medicine at UCLA, Los Angeles, California 90073
| | - Xiaochun Teng
- the Institute of Endocrinology, China Medical University, Shenyang 110001, China
| | - Sina Rabi
- From the Molecular Endocrinology Laboratory, Veterans Affairs Greater Los Angeles Healthcare System and Departments of Medicine and Physiology, David Geffen School of Medicine at UCLA, Los Angeles, California 90073
| | - Ysutada Akiba
- From the Molecular Endocrinology Laboratory, Veterans Affairs Greater Los Angeles Healthcare System and Departments of Medicine and Physiology, David Geffen School of Medicine at UCLA, Los Angeles, California 90073
| | - Gregory A Brent
- From the Molecular Endocrinology Laboratory, Veterans Affairs Greater Los Angeles Healthcare System and Departments of Medicine and Physiology, David Geffen School of Medicine at UCLA, Los Angeles, California 90073,
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3
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Inagaki T, Iwasaki S, Matsumura Y, Kawamura T, Tanaka T, Abe Y, Yamasaki A, Tsurutani Y, Yoshida A, Chikaoka Y, Nakamura K, Magoori K, Nakaki R, Osborne TF, Fukami K, Aburatani H, Kodama T, Sakai J. The FBXL10/KDM2B scaffolding protein associates with novel polycomb repressive complex-1 to regulate adipogenesis. J Biol Chem 2014; 290:4163-77. [PMID: 25533466 DOI: 10.1074/jbc.m114.626929] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Polycomb repressive complex 1 (PRC1) plays an essential role in the epigenetic repression of gene expression during development and cellular differentiation via multiple effector mechanisms, including ubiquitination of H2A and chromatin compaction. However, whether it regulates the stepwise progression of adipogenesis is unknown. Here, we show that FBXL10/KDM2B is an anti-adipogenic factor that is up-regulated during the early phase of 3T3-L1 preadipocyte differentiation and in adipose tissue in a diet-induced model of obesity. Interestingly, inhibition of adipogenesis does not require the JmjC demethylase domain of FBXL10, but it does require the F-box and leucine-rich repeat domains, which we show recruit a noncanonical polycomb repressive complex 1 (PRC1) containing RING1B, SKP1, PCGF1, and BCOR. Knockdown of either RING1B or SKP1 prevented FBXL10-mediated repression of 3T3-L1 preadipocyte differentiation indicating that PRC1 formation mediates the inhibitory effect of FBXL10 on adipogenesis. Using ChIP-seq, we show that FBXL10 recruits RING1B to key specific genomic loci surrounding the key cell cycle and the adipogenic genes Cdk1, Uhrf1, Pparg1, and Pparg2 to repress adipogenesis. These results suggest that FBXL10 represses adipogenesis by targeting a noncanonical PRC1 complex to repress key genes (e.g. Pparg) that control conversion of pluripotent cells into the adipogenic lineage.
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Affiliation(s)
- Takeshi Inagaki
- From the Division of Metabolic Medicine, the Translational Systems Biology and Medicine Initiative Center for Disease Biology and Integrative Medicine, University of Tokyo, Tokyo 153-8904, Japan,
| | | | | | - Takeshi Kawamura
- the Translational Systems Biology and Medicine Initiative Center for Disease Biology and Integrative Medicine, University of Tokyo, Tokyo 153-8904, Japan, Laboratory for Systems Biology and Medicine
| | - Toshiya Tanaka
- From the Division of Metabolic Medicine, the Translational Systems Biology and Medicine Initiative Center for Disease Biology and Integrative Medicine, University of Tokyo, Tokyo 153-8904, Japan, Laboratory for Systems Biology and Medicine
| | - Yohei Abe
- From the Division of Metabolic Medicine
| | | | | | - Ayano Yoshida
- From the Division of Metabolic Medicine, the Laboratory of Genome and Biosignals, Tokyo University of Pharmacy and Life Science, Tokyo 192-0392, Japan
| | - Yoko Chikaoka
- the Translational Systems Biology and Medicine Initiative Center for Disease Biology and Integrative Medicine, University of Tokyo, Tokyo 153-8904, Japan, Laboratory for Systems Biology and Medicine
| | - Kanako Nakamura
- From the Division of Metabolic Medicine, the Laboratory of Genome and Biosignals, Tokyo University of Pharmacy and Life Science, Tokyo 192-0392, Japan
| | - Kenta Magoori
- From the Division of Metabolic Medicine, the Translational Systems Biology and Medicine Initiative Center for Disease Biology and Integrative Medicine, University of Tokyo, Tokyo 153-8904, Japan
| | - Ryo Nakaki
- Genome Science Division, Research Center for Advanced Science and Technology, University of Tokyo, Tokyo 153-8904, Japan
| | - Timothy F Osborne
- the Metabolic Disease Program, Sanford-Burnham Medical Research Institute, Orlando, Florida 32827, and
| | - Kiyoko Fukami
- the Laboratory of Genome and Biosignals, Tokyo University of Pharmacy and Life Science, Tokyo 192-0392, Japan
| | - Hiroyuki Aburatani
- the Translational Systems Biology and Medicine Initiative Center for Disease Biology and Integrative Medicine, University of Tokyo, Tokyo 153-8904, Japan, Genome Science Division, Research Center for Advanced Science and Technology, University of Tokyo, Tokyo 153-8904, Japan
| | | | - Juro Sakai
- From the Division of Metabolic Medicine, the Translational Systems Biology and Medicine Initiative Center for Disease Biology and Integrative Medicine, University of Tokyo, Tokyo 153-8904, Japan,
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4
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Li C, Mpollo MSEM, Gonsalves CS, Tahara SM, Malik P, Kalra VK. Peroxisome proliferator-activated receptor-α-mediated transcription of miR-199a2 attenuates endothelin-1 expression via hypoxia-inducible factor-1α. J Biol Chem 2014; 289:36031-47. [PMID: 25389292 DOI: 10.1074/jbc.m114.600775] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Endothelin-1, a potent vasoconstrictor, plays an important role in pulmonary hypertension (PH) in sickle cell disease (SCD). Our previous studies show that higher levels of placenta growth factor (PlGF), secreted by erythroid precursor cells, correlate with increased plasma levels of endothelin-1 (ET-1) and other functional markers of PH in SCD. PlGF-mediated ET-1 expression occurs via activation of hypoxia-inducible factor-1α (HIF-1α). However, relatively less is understood regarding how PlGF-mediated expression of HIF-1α and its downstream effector ET-1 are post-transcriptionally regulated. Herein, we show that PlGF treatment of endothelial cells resulted in reduced levels of miR-199a2, which targeted the 3'-UTR of HIF-1α mRNA and concomitantly led to augmented ET-1 expression. Plasma levels of miR-199a2 in SCD subjects were significantly lower with reciprocally high levels of plasma ET-1, unlike unaffected controls. This observation provided a molecular link between miR-199a2 and high levels of ET-1 in SCD. Furthermore, we show that miR-199a2 located in the DNM3os transcription unit was co-transcriptionally regulated by peroxisome proliferator-activated receptor α (PPARα). Binding of the latter to PPARα cis-elements in the promoter of DNM3os was demonstrated by promoter mutational analysis and ChIP. Additionally, we show that fenofibrate, a PPARα agonist, increased the expression of miR-199a2 and DNM3os; the former was responsible for reduced expression of HIF-1α and ET-1. In vivo studies of fenofibrate-fed Berkeley sickle mice resulted in increased levels of miR-199a2 and reduced levels of ET-1 in lung tissues. Our studies provide a potential therapeutic approach whereby fenofibrate-induced miR-199a2 expression can ameliorate PH by reduction of ET-1 levels.
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Affiliation(s)
- Chen Li
- From the Departments of Biochemistry and Molecular Biology and
| | - Marthe-Sandrine Eiymo Mwa Mpollo
- the Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229
| | | | - Stanley M Tahara
- Molecular Microbiology and Immunology, Keck School of Medicine of University of Southern California, Los Angeles, California 90089 and
| | - Punam Malik
- the Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229
| | - Vijay K Kalra
- From the Departments of Biochemistry and Molecular Biology and
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5
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Choi SS, Kim ES, Koh M, Lee SJ, Lim D, Yang YR, Jang HJ, Seo KA, Min SH, Lee IH, Park SB, Suh PG, Choi JH. A novel non-agonist peroxisome proliferator-activated receptor γ (PPARγ) ligand UHC1 blocks PPARγ phosphorylation by cyclin-dependent kinase 5 (CDK5) and improves insulin sensitivity. J Biol Chem 2014; 289:26618-26629. [PMID: 25100724 DOI: 10.1074/jbc.m114.566794] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Thiazolidinedione class of anti-diabetic drugs which are known as peroxisome proliferator-activated receptor γ (PPARγ) ligands have been used to treat metabolic disorders, but thiazolidinediones can also cause several severe side effects, including congestive heart failure, fluid retention, and weight gain. In this study, we describe a novel synthetic PPARγ ligand UNIST HYUNDAI Compound 1 (UHC1) that binds tightly to PPARγ without the classical agonism and which blocks cyclin-dependent kinase 5 (CDK5)-mediated PPARγ phosphorylation. We modified the non-agonist PPARγ ligand SR1664 chemically to improve its solubility and then developed a novel PPARγ ligand, UHC1. According to our docking simulation, UHC1 occupied the ligand-binding site of PPARγ with a higher docking score than SR1664. In addition, UHC1 more potently blocked CDK5-mediated PPARγ phosphorylation at Ser-273. Surprisingly, UHC1 treatment effectively ameliorated the inflammatory response both in vitro and in high-fat diet-fed mice. Furthermore, UHC1 treatment dramatically improved insulin sensitivity in high-fat diet-fed mice without causing fluid retention and weight gain. Taken together, compared with SR1664, UHC1 exhibited greater beneficial effects on glucose and lipid metabolism by blocking CDK5-mediated PPARγ phosphorylation, and these data indicate that UHC1 could be a novel therapeutic agent for use in type 2 diabetes and related metabolic disorders.
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Affiliation(s)
- Sun-Sil Choi
- Department of Biological Science, Ulsan National Institute of Science and Technology, Ulsan 689-798, Korea
| | - Eun Sun Kim
- Department of Biological Science, Ulsan National Institute of Science and Technology, Ulsan 689-798, Korea
| | - Minseob Koh
- Department of Chemistry, Seoul National University, Seoul 151-747, Korea
| | - Soo-Jin Lee
- Department of Biological Science, Ulsan National Institute of Science and Technology, Ulsan 689-798, Korea
| | - Donghyun Lim
- New Drug Development Center, Daegu-Gyeongbuk Medical Innovation Foundation, 80 Cheombok-ro, Dong-gu, Daegu 701-310, Korea
| | - Yong Ryoul Yang
- Department of Biological Science, Ulsan National Institute of Science and Technology, Ulsan 689-798, Korea
| | - Hyun-Jun Jang
- Department of Biological Science, Ulsan National Institute of Science and Technology, Ulsan 689-798, Korea
| | - Kyung-Ah Seo
- Department of Biophysics and Chemical Biology/Bio-MAX Institute, Seoul National University, Seoul 151-747, Korea, and
| | - Sang-Hyun Min
- Department of Biophysics and Chemical Biology/Bio-MAX Institute, Seoul National University, Seoul 151-747, Korea, and
| | - In Hee Lee
- Department of Medical Chemistry, Hyundai Pharm Co., Ltd., Suwon, Gyonggi 443-270, Korea
| | - Seung Bum Park
- Department of Chemistry, Seoul National University, Seoul 151-747, Korea,; New Drug Development Center, Daegu-Gyeongbuk Medical Innovation Foundation, 80 Cheombok-ro, Dong-gu, Daegu 701-310, Korea
| | - Pann-Ghill Suh
- Department of Biological Science, Ulsan National Institute of Science and Technology, Ulsan 689-798, Korea
| | - Jang Hyun Choi
- Department of Biological Science, Ulsan National Institute of Science and Technology, Ulsan 689-798, Korea,.
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6
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Okamura A, Koyanagi S, Dilxiat A, Kusunose N, Chen JJ, Matsunaga N, Shibata S, Ohdo S. Bile acid-regulated peroxisome proliferator-activated receptor-α (PPARα) activity underlies circadian expression of intestinal peptide absorption transporter PepT1/Slc15a1. J Biol Chem 2014; 289:25296-305. [PMID: 25016014 DOI: 10.1074/jbc.m114.577023] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Digested proteins are mainly absorbed as small peptides composed of two or three amino acids. The intestinal absorption of small peptides is mediated via only one transport system: the proton-coupled peptide transporter-1 (PepT1) encoded from the soluble carrier protein Slc15a1. In mammals, intestinal expression of PepT1/Slc15a1 oscillates during the daily feeding cycle. Although the oscillation in the intestinal expression of PepT1/Slc15a1 is suggested to be controlled by molecular components of circadian clock, we demonstrated here that bile acids regulated the oscillation of PepT1/Slc15a1 expression through modulating the activity of peroxisome proliferator-activated receptor α (PPARα). Nocturnally active mice mainly consumed their food during the dark phase. PPARα activated the intestinal expression of Slc15a1 mRNA during the light period, and protein levels of PepT1 peaked before the start of the dark phase. After food intake, bile acids accumulated in intestinal epithelial cells. Intestinal accumulated bile acids interfered with recruitment of co-transcriptional activator CREB-binding protein/p300 on the promoter region of Slc15a1 gene, thereby suppressing PPARα-mediated transactivation of Slc15a1. The time-dependent suppression of PPARα-mediated transactivation by bile acids caused an oscillation in the intestinal expression of PepT1/Slc15a1 during the daily feeding cycle that led to circadian changes in the intestinal absorption of small peptides. These findings suggest a molecular clock-independent mechanism by which bile acid-regulated PPARα activity governs the circadian expression of intestinal peptide transporter.
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Affiliation(s)
- Ayako Okamura
- From the Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan and
| | - Satoru Koyanagi
- From the Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan and
| | - Adila Dilxiat
- From the Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan and
| | - Naoki Kusunose
- From the Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan and
| | - Jia Jun Chen
- From the Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan and
| | - Naoya Matsunaga
- From the Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan and
| | - Shigenobu Shibata
- Laboratory of Physiology and Pharmacology, School of Advanced Science and Engineering, Waseda University, Tokyo 162-8480, Japan
| | - Shigehiro Ohdo
- From the Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan and
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7
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Li J, Bi L, Hulke M, Li T. Fish oil and fenofibrate prevented phosphorylation-dependent hepatic sortilin 1 degradation in Western diet-fed mice. J Biol Chem 2014; 289:22437-49. [PMID: 24986865 DOI: 10.1074/jbc.m114.548933] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Obesity and diabetes are associated with hepatic triglyceride overproduction and hypertriglyceridemia. Recent studies have found that the cellular trafficking receptor sortilin 1 (Sort1) inhibits hepatic apolipoprotein B secretion and reduces plasma lipid levels in mice, and its hepatic expression was negatively associated with plasma lipids in humans. This study investigated the regulation of hepatic Sort1 under diabetic conditions and by lipid-lowering fish oil and fenofibrate. Results showed that hepatic Sort1 protein, but not mRNA, was markedly lower in Western diet-fed mice. Knockdown of hepatic Sort1 increased plasma triglyceride in mice. Feeding mice a fish oil-enriched diet completely restored hepatic Sort1 levels in Western diet-fed mice. Fenofibrate also restored hepatic Sort1 protein levels in Western diet-fed wild type mice, but not in peroxisome proliferator-activated receptor α (PPARα) knock-out mice. PPARα ligands did not induce Sort1 in hepatocytes in vitro. Instead, fish oil and fenofibrate reduced circulating and hepatic fatty acids in mice, and n-3 polyunsaturated fatty acids prevented palmitate inhibition of Sort1 protein in HepG2 cells. LC/MS/MS analysis revealed that Sort1 phosphorylation at serine 793 was increased in obese mice and in palmitate-treated HepG2 cells. Mutations that abolished phosphorylation at Ser-793 increased Sort1 stability and prevented palmitate inhibition of Sort1 ubiquitination and degradation in HepG2 cells. In summary, therapeutic strategies that prevent posttranslational hepatic Sort1 down-regulation in obesity and diabetes may be beneficial in improving dyslipidemia.
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Affiliation(s)
- Jibiao Li
- From the Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, Kansas 66160
| | - Lipeng Bi
- From the Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, Kansas 66160
| | - Michelle Hulke
- From the Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, Kansas 66160
| | - Tiangang Li
- From the Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, Kansas 66160
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8
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Liu B, Wang T, Mei W, Li D, Cai R, Zuo Y, Cheng J. Small ubiquitin-like modifier (SUMO) protein-specific protease 1 de-SUMOylates Sharp-1 protein and controls adipocyte differentiation. J Biol Chem 2014; 289:22358-64. [PMID: 24942744 DOI: 10.1074/jbc.m114.571950] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Adipocyte differentiation is regulated by a transcriptional cascade that mainly includes CCAAT/enhancer-binding protein family members and the nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ). Here we show the defects in adipocyte differentiation as well as PPARγ expression in Senp1(-/-) mouse embryonic fibroblast cells induced by adipogenic stimuli. We further determine that SENP1 is a specific de-SUMOylation protease for Sharp-1, a repressor for PPARγ transcription and adipogenesis. SENP1 enhances adipogenesis through de-SUMOylation of Sharp-1, which then releases Sharp-1 repression of PPARγ expression and adipocyte differentiation. These results reveal SENP1 as a novel regulator in adipogenesis.
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Affiliation(s)
- Bingting Liu
- From the Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation and State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Tianshi Wang
- From the Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation and State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Wenhan Mei
- From the Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation and
| | - Dongdong Li
- From the Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation and
| | - Rong Cai
- From the Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation and
| | - Yong Zuo
- From the Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation and State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Jinke Cheng
- From the Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation and State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
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9
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Mattijssen F, Georgiadi A, Andasarie T, Szalowska E, Zota A, Krones-Herzig A, Heier C, Ratman D, De Bosscher K, Qi L, Zechner R, Herzig S, Kersten S. Hypoxia-inducible lipid droplet-associated (HILPDA) is a novel peroxisome proliferator-activated receptor (PPAR) target involved in hepatic triglyceride secretion. J Biol Chem 2014; 289:19279-93. [PMID: 24876382 DOI: 10.1074/jbc.m114.570044] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Peroxisome proliferator-activated receptors (PPARs) play major roles in the regulation of hepatic lipid metabolism through the control of numerous genes involved in processes such as lipid uptake and fatty acid oxidation. Here we identify hypoxia-inducible lipid droplet-associated (Hilpda/Hig2) as a novel PPAR target gene and demonstrate its involvement in hepatic lipid metabolism. Microarray analysis revealed that Hilpda is one of the most highly induced genes by the PPARα agonist Wy14643 in mouse precision cut liver slices. Induction of Hilpda mRNA by Wy14643 was confirmed in mouse and human hepatocytes. Oral dosing with Wy14643 similarly induced Hilpda mRNA levels in livers of wild-type mice but not Ppara(-/-) mice. Transactivation studies and chromatin immunoprecipitation showed that Hilpda is a direct PPARα target gene via a conserved PPAR response element located 1200 base pairs upstream of the transcription start site. Hepatic overexpression of HILPDA in mice via adeno-associated virus led to a 4-fold increase in liver triglyceride storage, without any changes in key genes involved in de novo lipogenesis, β-oxidation, or lipolysis. Moreover, intracellular lipase activity was not affected by HILPDA overexpression. Strikingly, HILPDA overexpression significantly impaired hepatic triglyceride secretion. Taken together, our data uncover HILPDA as a novel PPAR target that raises hepatic triglyceride storage via regulation of triglyceride secretion.
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Affiliation(s)
- Frits Mattijssen
- From the Nutrition, Metabolism, and Genomics Group, Division of Human Nutrition, Wageningen University, 6700 EV Wageningen, The Netherlands
| | - Anastasia Georgiadi
- From the Nutrition, Metabolism, and Genomics Group, Division of Human Nutrition, Wageningen University, 6700 EV Wageningen, The Netherlands
| | - Tresty Andasarie
- From the Nutrition, Metabolism, and Genomics Group, Division of Human Nutrition, Wageningen University, 6700 EV Wageningen, The Netherlands
| | - Ewa Szalowska
- the RIKILT-Institute of Food Safety, Wageningen University and Research Centre, 6700AE Wageningen, The Netherlands
| | - Annika Zota
- the Joint Division Molecular Metabolic Control, DKFZ-ZMBH Alliance, Network Aging Research, German Cancer Research Center (DKFZ) Heidelberg, Center for Molecular Biology (ZMBH), and University Hospital, Heidelberg University, 69120 Heidelberg, Germany
| | - Anja Krones-Herzig
- the Joint Division Molecular Metabolic Control, DKFZ-ZMBH Alliance, Network Aging Research, German Cancer Research Center (DKFZ) Heidelberg, Center for Molecular Biology (ZMBH), and University Hospital, Heidelberg University, 69120 Heidelberg, Germany
| | - Christoph Heier
- the Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Dariusz Ratman
- the Cytokine Receptor Laboratory, Nuclear Receptor Signaling Unit, Department of Medical Protein Research, Flanders Institute for Biotechnology, University of Ghent, Albert Baertsoenkaai 3, B-9000 Gent, Belgium, and
| | - Karolien De Bosscher
- the Cytokine Receptor Laboratory, Nuclear Receptor Signaling Unit, Department of Medical Protein Research, Flanders Institute for Biotechnology, University of Ghent, Albert Baertsoenkaai 3, B-9000 Gent, Belgium, and
| | - Ling Qi
- the Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853
| | - Rudolf Zechner
- the Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Stephan Herzig
- the Joint Division Molecular Metabolic Control, DKFZ-ZMBH Alliance, Network Aging Research, German Cancer Research Center (DKFZ) Heidelberg, Center for Molecular Biology (ZMBH), and University Hospital, Heidelberg University, 69120 Heidelberg, Germany
| | - Sander Kersten
- From the Nutrition, Metabolism, and Genomics Group, Division of Human Nutrition, Wageningen University, 6700 EV Wageningen, The Netherlands, the Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853
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10
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Yu S, Levi L, Casadesus G, Kunos G, Noy N. Fatty acid-binding protein 5 (FABP5) regulates cognitive function both by decreasing anandamide levels and by activating the nuclear receptor peroxisome proliferator-activated receptor β/δ (PPARβ/δ) in the brain. J Biol Chem 2014; 289:12748-58. [PMID: 24644281 DOI: 10.1074/jbc.m114.559062] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Endocannabinoids modulate multiple behaviors, including learning and memory. We show that the endocannabinoid anandamide (AEA) can alter neuronal cell function both through its established role in activation of the G-protein-coupled receptor CB1, and by serving as a precursor for a potent agonist of the nuclear receptor PPARβ/δ, in turn up-regulating multiple cognition-associated genes. We show further that the fatty acid-binding protein FABP5 controls both of these functions in vivo. FABP5 both promotes the hydrolysis of AEA into arachidonic acid and thus reduces brain endocannabinoid levels, and directly shuttles arachidonic acid to the nucleus where it delivers it to PPARβ/δ, enabling its activation. In accordance, ablation of FABP5 in mice results in excess accumulation of AEA, abolishes PPARβ/δ activation in the brain, and markedly impairs hippocampus-based learning and memory. The data indicate that, by controlling anandamide disposition and activities, FABP5 plays a key role in regulating hippocampal cognitive function.
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11
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Duan Z, Zhao X, Fu X, Su C, Xin L, Saarikettu J, Yang X, Yao Z, Silvennoinen O, Wei M, Yang J. Tudor-SN, a novel coactivator of peroxisome proliferator-activated receptor γ protein, is essential for adipogenesis. J Biol Chem 2014; 289:8364-74. [PMID: 24523408 DOI: 10.1074/jbc.m113.523456] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Adipogenesis, in which mesenchymal precursor cells differentiate into mature adipocytes, is a well orchestrated process. In the present study we identified Tudor-SN as a novel co-activator of the transcription factor peroxisome proliferator-activated receptor γ (PPARγ). We provide the first evidence that Tudor-SN and PPARγ exist in the same complex. Both are up-regulated by the early factor C/EBPβ during adipogenesis and significantly influence the regulation of PPARγ target genes in both 3T3-L1 pre-adipocyte and mouse embryonic fibroblasts (MEF) upon exposure to a mixture of hormonal mixture. Moreover, aP2-PPARγ response element (PPRE) interacts with both PPARγ and Tudor-SN, and the gene transcriptional activation of PPRE-luc is enhanced by ectopic expression of Tudor-SN. Deletion of Tudor-SN protein (MEF-KO) affects but does not completely abolish the association of PPARγ and aP2-PPRE. Loss-of-function studies further verified that Tudor-SN is required for adipogenesis, as deletion of Tudor-SN (MEF-KO) impairs dexamethasone, 3-isobutyl-1-methylxanthine, and insulin (DMI)-induced adipocyte differentiation and the expression of PPARγ target genes, such as aP2 and adipsin. Furthermore, H3 acetylation levels were lower in MEF-KO than MEF-WT. Both HDAC1 and HDAC3 are stably associated with PPARγ in MEF-KO, whereas only a small amount of association was observed in MEF-WT after 5 days of treatment during adipogenesis. PPARγ requires various co-activators or co-repressors, which may dynamically associate with and regulate the higher order chromatin remodeling of the promoter region of PPARγ-bound target genes; Tudor-SN is likely one of these co-activators.
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Affiliation(s)
- Zhongchao Duan
- From the Department of Biochemistry and Molecular Biology, Department of Immunology, School of Basic Medical Sciences
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12
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Gilardi F, Giudici M, Mitro N, Maschi O, Guerrini U, Rando G, Maggi A, Cermenati G, Laghezza A, Loiodice F, Pochetti G, Lavecchia A, Caruso D, De Fabiani E, Bamberg K, Crestani M. LT175 is a novel PPARα/γ ligand with potent insulin-sensitizing effects and reduced adipogenic properties. J Biol Chem 2014; 289:6908-6920. [PMID: 24451380 DOI: 10.1074/jbc.m113.506394] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Peroxisome proliferator-activated receptors (PPARs) are ligand-dependent transcription factors regulating lipid and glucose metabolism. Ongoing drug discovery programs aim to develop dual PPARα/γ agonists devoid of the side effects of the marketed antidiabetic agents thiazolidinediones and the dual agonists glitazars. Recently, we described a new dual PPARα/γ ligand, LT175, with a partial agonist profile against PPARγ and interacting with a newly identified region of the PPARγ-ligand binding domain (1). Here we show that LT175 differentially activated PPARγ target genes involved in fatty acid esterification and storage in 3T3-L1-derived adipocytes. This resulted in a less severe lipid accumulation compared with that triggered by rosiglitazone, suggesting that LT175 may have a lower adipogenic activity. Consistent with this hypothesis, in vivo administration of LT175 to mice fed a high-fat diet decreased body weight, adipocyte size, and white adipose tissue mass, as assessed by magnetic resonance imaging. Furthermore, LT175 significantly reduced plasma glucose, insulin, non-esterified fatty acids, triglycerides, and cholesterol and increased circulating adiponectin and fibroblast growth factor 21 levels. Oral glucose and insulin tolerance tests showed that the compound improves glucose homeostasis and insulin sensitivity. Moreover, we demonstrate that the peculiar interaction of LT175 with PPARγ affected the recruitment of the coregulators cyclic-AMP response element-binding protein-binding protein and nuclear corepressor 1 (NCoR1), fundamentals for the PPARγ-mediated adipogenic program. In conclusion, our results describe a new PPAR ligand, modulating lipid and glucose metabolism with reduced adipogenic activity, that may be used as a model for a series of novel molecules with an improved pharmacological profile for the treatment of dyslipidemia and type 2 diabetes.
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Affiliation(s)
- Federica Gilardi
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, 20133 Milan, Italy
| | - Marco Giudici
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, 20133 Milan, Italy
| | - Nico Mitro
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, 20133 Milan, Italy
| | - Omar Maschi
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, 20133 Milan, Italy
| | - Uliano Guerrini
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, 20133 Milan, Italy
| | - Gianpaolo Rando
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, 20133 Milan, Italy
| | - Adriana Maggi
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, 20133 Milan, Italy
| | - Gaia Cermenati
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, 20133 Milan, Italy
| | - Antonio Laghezza
- Dipartimento di Farmacia-Scienze del Farmaco, Università degli Studi di Bari "Aldo Moro", 70125 Bari, Italy
| | - Fulvio Loiodice
- Dipartimento di Farmacia-Scienze del Farmaco, Università degli Studi di Bari "Aldo Moro", 70125 Bari, Italy
| | - Giorgio Pochetti
- Consiglio Nazionale delle Ricerche (CNR), 00016 Montelibretti, Rome, Italy
| | - Antonio Lavecchia
- Dipartimento di Farmacia, "Drug Discovery" Laboratory, Università degli Studi di Napoli "Federico II", 80131 Naples, Italy
| | - Donatella Caruso
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, 20133 Milan, Italy
| | - Emma De Fabiani
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, 20133 Milan, Italy
| | | | - Maurizio Crestani
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, 20133 Milan, Italy.
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13
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Spruiell K, Richardson RM, Cullen JM, Awumey EM, Gonzalez FJ, Gyamfi MA. Role of pregnane X receptor in obesity and glucose homeostasis in male mice. J Biol Chem 2013; 289:3244-61. [PMID: 24362030 DOI: 10.1074/jbc.m113.494575] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Clinical obesity is a complex metabolic disorder affecting one in three adults. Recent reports suggest that pregnane X receptor (PXR), a xenobiotic nuclear receptor important for defense against toxic agents and for eliminating drugs and other xenobiotics, may be involved in obesity. Noting differences in ligand specificities between human and mouse PXRs, the role of PXR in high fat diet (HFD)-induced obesity was examined using male PXR-humanized (hPXR) transgenic and PXR-knock-out (PXR-KO) mice in comparison to wild-type (WT) mice. After 16 weeks on either a control diet or HFD, WT mice showed greater weight gain, whereas PXR-KO mice gained less weight due to their resistance to HFD-induced decreases in adipose tissue peroxisome proliferator-activated receptor α and induction of hepatic carnitine palmitoyltransferase 1, suggesting increased energy metabolism. Interestingly, control-fed PXR-KO mice exhibited hepatomegaly, hyperinsulinemia, and hyperleptinemia but hypoadiponectinemia and lower adiponectin receptor R2 mRNA levels relative to WT mice. Evaluation of these biologic indicators in hPXR mice fed a control diet or HFD revealed further differences between the mouse and human receptors. Importantly, although HFD-fed hPXR mice were resistant to HFD-induced obesity, both PXR-KO and hPXR mice exhibited impaired induction of glucokinase involved in glucose utilization and displayed elevated fasting glucose levels and severely impaired glucose tolerance. Moreover, the basal hepatic levels of the gluconeogenic enzyme phosphoenolpyruvate carboxykinase 1 were increased in hPXR mice compared with WT mice. Altogether, although the mouse PXR promotes HFD-induced obesity, the hPXR mouse carries a genetic predisposition for type 2 diabetes and thus provides a model for exploring the role of human PXR in the metabolic syndrome.
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Affiliation(s)
- Krisstonia Spruiell
- From the Julius L. Chambers Biomedical Biotechnology Research Institute, North Carolina Central University, Durham, North Carolina 27707
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14
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Kim J, Kwak HJ, Cha JY, Jeong YS, Rhee SD, Cheon HG. The role of prolyl hydroxylase domain protein (PHD) during rosiglitazone-induced adipocyte differentiation. J Biol Chem 2013; 289:2755-64. [PMID: 24338020 DOI: 10.1074/jbc.m113.493650] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Rosiglitazone, a well known insulin sensitizer, stimulates adipocyte differentiation via the activation of peroxisome proliferator-activated receptor γ (PPARγ). Previous two-dimensional proteomics studies using C3H10T1/2 murine mesenchymal pluripotent stem cells revealed that prolyl hydroxylase domain protein (PHD) levels significantly increased during rosiglitazone-induced adipocyte differentiation (RIAD). In this study, we investigated the functional role played by PHD during RIAD. Three PHD isoforms (PHD1, 2, and 3) were found to be up-regulated in C3H10T1/2 cells during RIAD, whereas PHD knockdown and treatment with PHD inhibitors (dimethyloxalyl glycine or ethyl-3,4-dihydroxybenzoate) blocked RIAD. PHD inhibition was found to be associated with increases in the levels of anti-adipogenic proteins such as GATA-3, KLF-2, and transcriptional coactivator with PDZ binding motif (TAZ), with their reduced ubiquitination, suggesting that PHDs evoke the ubiquitination/proteasomal degradation of anti-adipogenic proteins. On the other hand, MG-132 (a proteasomal inhibitor) prevented the degradation of anti-adipogenic proteins and retarded RIAD. PPARγ antagonists (bisphenol A diglycidyl ether or GW9662) blunted the effects of rosiglitazone on PHD regulation. Furthermore, putative PPARγ binding sites were identified in the promoter region of PHDs by ChIP-PCR, implying that rosiglitazone may induce PHD up-regulation directly by PPARγ activation. Consistent with in vitro results, oral administration of rosiglitazone to ob/ob mice for 2 weeks increased adipose PHD levels and decreased anti-adipogenic protein levels by increasing their ubiquitination. These results suggest that rosiglitazone increases PHD expression in a PPARγ-dependent manner and that this leads to the commitment of anti-adipogenic proteins to the ubiquitination-proteasomal pathway and to the subsequent induction of adipocyte differentiation.
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Affiliation(s)
- Juyoung Kim
- From the Department of Pharmacology School of Medicine and
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15
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Oger F, Dubois-Chevalier J, Gheeraert C, Avner S, Durand E, Froguel P, Salbert G, Staels B, Lefebvre P, Eeckhoute J. Peroxisome proliferator-activated receptor γ regulates genes involved in insulin/insulin-like growth factor signaling and lipid metabolism during adipogenesis through functionally distinct enhancer classes. J Biol Chem 2013; 289:708-22. [PMID: 24288131 DOI: 10.1074/jbc.m113.526996] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The nuclear receptor peroxisome proliferator-activated receptor (PPAR) is a transcription factor whose expression is induced during adipogenesis and that is required for the acquisition and control of mature adipocyte functions. Indeed, PPAR induces the expression of genes involved in lipid synthesis and storage through enhancers activated during adipocyte differentiation. Here, we show that PPAR also binds to enhancers already active in preadipocytes as evidenced by an active chromatin state including lower DNA methylation levels despite higher CpG content. These constitutive enhancers are linked to genes involved in the insulin/insulin-like growth factor signaling pathway that are transcriptionally induced during adipogenesis but to a lower extent than lipid metabolism genes, because of stronger basal expression levels in preadipocytes. This is consistent with the sequential involvement of hormonal sensitivity and lipid handling during adipocyte maturation and correlates with the chromatin structure dynamics at constitutive and activated enhancers. Interestingly, constitutive enhancers are evolutionary conserved and can be activated in other tissues, in contrast to enhancers controlling lipid handling genes whose activation is more restricted to adipocytes. Thus, PPAR utilizes both broadly active and cell type-specific enhancers to modulate the dynamic range of activation of genes involved in the adipogenic process.
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16
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Viswakarma N, Jia Y, Bai L, Gao Q, Lin B, Zhang X, Misra P, Rana A, Jain S, Gonzalez FJ, Zhu YJ, Thimmapaya B, Reddy JK. The Med1 subunit of the mediator complex induces liver cell proliferation and is phosphorylated by AMP kinase. J Biol Chem 2013; 288:27898-911. [PMID: 23943624 DOI: 10.1074/jbc.m113.486696] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mediator, a large multisubunit protein complex, plays a pivotal role in gene transcription by linking gene-specific transcription factors with the preinitiation complex and RNA polymerase II. In the liver, the key subunit of the Mediator complex, Med1, interacts with several nuclear receptors and transcription factors to direct gene-specific transcription. Conditional knock-out of Med1 in the liver showed that hepatocytes lacking Med1 did not regenerate following either partial hepatectomy or treatment with certain nuclear receptor activators and failed to give rise to tumors when challenged with carcinogens. We now report that the adenovirally driven overexpression of Med1 in mouse liver stimulates hepatocyte DNA synthesis with enhanced expression of DNA replication, cell cycle control, and liver-specific genes, indicating that Med1 alone is necessary and sufficient for liver cell proliferation. Importantly, we demonstrate that AMP-activated protein kinase (AMPK), an important cellular energy sensor, interacts with, and directly phosphorylates, Med1 in vitro at serine 656, serine 756, and serine 796. AMPK also phosphorylates Med1 in vivo in mouse liver and in cultured primary hepatocytes and HEK293 and HeLa cells. In addition, we demonstrate that PPARα activators increase AMPK-mediated Med1 phosphorylation in vivo. Inhibition of AMPK by compound C decreased hepatocyte proliferation induced by Med1 and also by the PPARα activators fenofibrate and Wy-14,643. Co-treatment with compound C attenuated PPARα activator-inducible fatty acid β-oxidation in liver. Our results suggest that Med1 phosphorylation by its association with AMPK regulates liver cell proliferation and fatty acid oxidation, most likely as a downstream effector of PPARα and AMPK.
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Affiliation(s)
- Navin Viswakarma
- From the Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
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