1
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Wang L, Xie W, Zhang L, Li D, Yu H, Xiong J, Peng J, Qiu J, Sheng H, He X, Zhang K. CVB3 Nonstructural 2A Protein Modulates SREBP1a Signaling via the MEK/ERK Pathway. J Virol 2018; 92:e01060-18. [PMID: 30258014 PMCID: PMC6258932 DOI: 10.1128/jvi.01060-18] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 09/10/2018] [Indexed: 01/11/2023] Open
Abstract
Coxsackievirus B3 (CVB3) is the predominant pathogen of viral myocarditis. In our previous study, we found that CVB3 caused abnormal lipid accumulation in host cells. However, the underlying mechanisms by which CVB3 disrupts and exploits the host lipid metabolism are not well understood. Sterol regulatory element binding protein 1 (SREBP1) is the major transcriptional factor in lipogenic genes expression. In this study, we demonstrated that CVB3 infection and nonstructural 2A protein upregulated and activated SREBP1a at the transcriptional level. Deletion analysis of SREBP1a promoter revealed that two regions, -1821/-1490 and -312/+217, in this promoter were both required for its activation by 2A. These promoter regions possessed several binding motifs for transcription factor SP1. Next, we used SP1-specific small interfering RNAs (siRNAs) to confirm that SP1 might be the essential factor in SREBP1a upregulation by 2A. Furthermore, we showed that MEK/ERK pathway was involved in the activation of SREBP1a by 2A and that blocking this signaling pathway with the specific inhibitor U0126 attenuated SREBP1a activation and lipid accumulation by 2A. Finally, we showed that inhibition of SREBP1 with siRNAs attenuated lipid accumulation induced by CVB3 infection and reduced virus replication. Moreover, inhibition of the MEK/ERK pathway also led to reduction of SREBP1a activation, lipid accumulation, and virus replication during CVB3 infection. Taken together, these data demonstrate that CVB3 nonstructural 2A protein activates SREBP1a at the transcription level through a mechanism involving MEK/ERK signaling pathway and SP1 transcription factor, which promotes cellular lipid accumulation and benefits virus replication.IMPORTANCE Coxsackievirus B3 (CVB3) infection is the leading cause of viral myocarditis, but effective vaccines and antiviral therapies against CVB3 infection are still lacking. It is important to understand the precise interactions between host and virus for the rational design of effective therapies. During infection, CVB3 disrupts and exploits host lipid metabolism to promote excessive lipid accumulation, which benefits virus replication. SREBP1 is the master regulator of cellular lipid metabolism. Here, we report that one of the viral nonstructural proteins, 2A, upregulates and activates SREBP1a. Furthermore, we find that inhibition of SREBP1 decreases CVB3 virus replication. These results reveal the regulation of SREBP1a expression by 2A and the roles of SREBP1 in lipid accumulation and viral replication during CVB3 infection. Our findings provide a new insight into CVB3 host interactions and inform a potential novel therapeutic target for this important pathogen.
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Affiliation(s)
- Lei Wang
- Central Laboratory, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
- The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Wei Xie
- Central Laboratory, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
- The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Le Zhang
- Central Laboratory, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Defeng Li
- Central Laboratory, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Hua Yu
- Central Laboratory, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Junzhi Xiong
- Central Laboratory, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Jin Peng
- Central Laboratory, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Jing Qiu
- Central Laboratory, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Halei Sheng
- Central Laboratory, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Xiaomei He
- Central Laboratory, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
| | - Kebin Zhang
- Central Laboratory, Xinqiao Hospital, Army Medical University (Third Military Medical University), Chongqing, China
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2
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Davis W, Tew KD. ATP-binding cassette transporter-2 (ABCA2) as a therapeutic target. Biochem Pharmacol 2017; 151:188-200. [PMID: 29223352 DOI: 10.1016/j.bcp.2017.11.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 11/27/2017] [Indexed: 12/28/2022]
Abstract
The ATP binding cassette transporter ABCA2 is primarily an endolysosomal membrane protein that demonstrates pleiotropic functionalities, coalescing around the maintenance of homeostasis of sterols, sphingolipids and cholesterol. It is most highly expressed in brain tissue and ABCA2 knockout mice express neurological defects consistent with aberrant myelination. Increased expression of the transporter has been linked with resistance to cancer drugs, particularly those possessing a steroid backbone and gene expression (in concert with other genes involved in cholesterol metabolism) was found to be regulated by sterols. Moreover, in macrophages ABCA2 is influenced by sterols and has a role in regulating cholesterol sequestration, potentially important in cardiovascular disease. Accumulating data indicate the critical importance of ABCA2 in mediating movement of sphingolipids within cellular compartments and these have been implicated in various aspects of cholesterol trafficking. Perhaps because the functions of ABCA2 are linked with membrane building blocks, there are reports linking it with human pathologies, including, cholesterolemias and cardiovascular disease, Alzheimer's and cancer. The present review addresses whether there is now sufficient information to consider ABCA2 as a plausible therapeutic target.
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Affiliation(s)
- Warren Davis
- Dept. of Cell & Molecular Pharmacology & Experimental Therapeutics, Medical University of South Carolina, 173 Ashley Avenue, BSB, MSC 509, Charleston, SC 29425, United States
| | - Kenneth D Tew
- Dept. of Cell & Molecular Pharmacology & Experimental Therapeutics, Medical University of South Carolina, 173 Ashley Avenue, BSB, MSC 509, Charleston, SC 29425, United States.
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3
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Abd Eldaim MA, Matsuoka S, Okamatsu-Ogura Y, Kamikawa A, Ahmed MM, Terao A, Nakajima KI, Kimura K. Retinoic acid modulates lipid accumulation glucose concentration dependently through inverse regulation of SREBP-1 expression in 3T3L1 adipocytes. Genes Cells 2017; 22:568-582. [PMID: 28488421 DOI: 10.1111/gtc.12498] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 03/29/2017] [Indexed: 12/19/2022]
Abstract
It is well known that retinoic acid (RA) suppresses adipogenesis, although there are some contradicting reports. In this study, we examined the effect of extracellular glucose on RA-induced suppression of adipogenesis in 3T3L1 cell culture. When the cells were cultured in normal glucose medium (NG), the addition of RA suppressed lipid accumulation. However, when cultured in high glucose medium (HG), addition of RA to the cells enhanced lipid accumulation. These changes were accompanied by parallel alterations in fatty acid synthase (FAS) and sterol regulatory element-binding protein (SREBP)-1 gene expression. Transfection of SREBP-1 siRNA suppressed RA-induced enhancement of lipid accumulation and FAS expression in the cells cultured with HG. Transfection of the nuclear form of SREBP-1a cDNA into the cells cultured with NG inhibited RA-induced suppression of lipid accumulation and FAS expression. Moreover, RA- and HG-induced SREBP-1a expression occurred at the early phase of adipogenesis and was dependent on glucocorticoid to induce liver X receptor (LXR) β, peroxisomal proliferator-activated receptor (PPAR) γ and retinoid X receptor (RXR), the key nuclear factors influencing the SREBP-1a gene expression. These results suggest that RA suppresses and enhances lipid accumulation through extracellular glucose concentration-dependent modulation of SREBP-1 expression.
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Affiliation(s)
- Mabrouk Attia Abd Eldaim
- Laboratories of Biochemistry, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, 060-0818, Japan.,Department of Biochemistry and Chemistry of Nutrition, Faculty of Veterinary Medicine, Menoufia University, Menoufia, 32721, Egypt
| | - Shinya Matsuoka
- Laboratories of Biochemistry, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, 060-0818, Japan
| | - Yuko Okamatsu-Ogura
- Laboratories of Biochemistry, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, 060-0818, Japan
| | - Akihiro Kamikawa
- Laboratories of Biochemistry, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, 060-0818, Japan
| | - Mohamed Mohamed Ahmed
- Laboratories of Biochemistry, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, 060-0818, Japan
| | - Akira Terao
- Laboratories of Biochemistry, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, 060-0818, Japan
| | - Kei-Ichi Nakajima
- National Agricultural Research Center for Hokkaido Region, Sapporo, 062-8555, Japan
| | - Kazuhiro Kimura
- Laboratories of Biochemistry, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, 060-0818, Japan
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4
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Bawazeer NA, Choudary H, Zamzami MA, Abdulaal WH, Zeyadi M, ALbukhari A, Middleton B, Moselhy SS. POSSIBLE REGULATION OF LDL-RECEPTOR BY NARINGENIN IN HEPG2 HEPATOMA CELL LINE. AFRICAN JOURNAL OF TRADITIONAL, COMPLEMENTARY, AND ALTERNATIVE MEDICINES 2016; 14:278-287. [PMID: 28480406 PMCID: PMC5411880 DOI: 10.21010/ajtcam.v14i1.30] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Background: High plasma concentration of low-density lipoprotein cholesterol (LDL-c) plays a significant role in the incidence of atherosclerosis and coronary heart diseases (CHD). Materials and Methods: The purpose of this study was to investigate the mechanism by which citrus flavonoids, naringenin regulate the LDL receptor (LDLr) gene in human liver using the human hepatoma cell line, HepG2 as a model. Results: Time-course transient transfection of HepG2 cells with luciferase reporter-gene constructs incorporating the promoters of SREBP-1a,-1c, -2 and LDLr, revealed that in lipoprotein-deficient medium (LPDM), only SREBP-1a promoter activity was increased significantly after 4h exposure to 200μM naringenin respectively. However, after 24h incubation with 200μM naringenin the gene expression activities of all the SREBP-1a, -1c, -2 and LDLr promoter-constructs were increased significantly. The effects of both 200μM naringenin on elevating LDLr mRNA are possibly due to regulation of gene transcription by SREBP-la and SREBP-2. However, the suppression effect of 200μM naringenin on hepatic SREBP-1c mRNA expression is likely associated with the reduction in mRNA expression of both acetyl-CoA carboxylase and fatty acid synthase in human hepatoma HepG2 cells. It was found that, 200μM naringenin was likely to stimulate LDLr gene expression via increase phosphorylation of PI3K and ERK1/2 which enhance the transcription factors SREBP-1a and SREBP-2 mRNA levels and increased their protein maturation in human hepatoma HepG2 cell. Conclusion: Diets supplemented with naringenin could effectively reduce mortality and morbidity from coronary heart diseases and as cardio-protective effects in humans.
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Affiliation(s)
- Nora A Bawazeer
- Department of Home Economics, Taif University, Taif, Saudi Arabia
| | - Hani Choudary
- Department of Biochemistry, Cancer Metabolism and Epigenetic Unit, Faculty of Science, Center of Innovation in Personalized Medicine, Cancer and Mutagenesis Unit, King Fahd Center for Medical Research, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Mazin A Zamzami
- Department of Biochemistry, Cancer Metabolism and Epigenetic Unit, Faculty of Science, Cancer and Mutagenesis Unit, King Fahd Center for Medical Research, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Wesam H Abdulaal
- Department of Biochemistry, Cancer Metabolism and Epigenetic Unit, Faculty of Science, Cancer and Mutagenesis Unit, King Fahd Center for Medical Research, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Mustafa Zeyadi
- Department of Biochemistry, Cancer Metabolism and Epigenetic Unit, Faculty of Science, Cancer and Mutagenesis Unit, King Fahd Center for Medical Research, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Ashwag ALbukhari
- Department of Biochemistry, Cancer Metabolism and Epigenetic Unit, Faculty of Science, Cancer and Mutagenesis Unit, King Fahd Center for Medical Research, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Bruce Middleton
- Department of Biochemistry, Medical School, Nottingham University, Nottingham, United Kingdom
| | - Said S Moselhy
- Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia and Department of Biochemistry, Faculty of Science, Ain shams University, Cairo, Egypt.,Experimental biochemistry unit, & Bioactive natural products research Group (KAU)
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5
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Arosh JA, Banu SK, McCracken JA. Novel concepts on the role of prostaglandins on luteal maintenance and maternal recognition and establishment of pregnancy in ruminants. J Dairy Sci 2016; 99:5926-5940. [PMID: 27179861 DOI: 10.3168/jds.2015-10335] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 02/03/2016] [Indexed: 11/19/2022]
Abstract
In ruminants, the corpus luteum (CL) of early pregnancy is resistant to luteolysis. Prostaglandin (PG)E2 is considered a luteoprotective mediator. Early studies indicate that during maternal recognition of pregnancy (MRP) in ruminants, a factor(s) from the conceptus or gravid uterus reaches the ovary locally through the utero-ovarian plexus (UOP) and protects the CL from luteolysis. The local nature of the embryonic antiluteolytic or luteoprotective effect precludes any direct effect of a protein transported or acting between the gravid uterus and CL in ruminants. During MRP, interferon tau (IFNT) secreted by the trophoblast of the conceptus inhibits endometrial pulsatile release of PGF2α and increases endometrial PGE2. Our recent studies indicate that (1) luteal PG biosynthesis is selectively directed toward PGF2α at the time of luteolysis and toward PGE2 at the time of establishment of pregnancy (ESP); (2) the ability of the CL of early pregnancy to resist luteolysis is likely due to increased intraluteal biosynthesis and signaling of PGE2; and (3) endometrial PGE2 is transported from the uterus to the CL through the UOP vascular route during ESP in sheep. Intrauterine co-administration of IFNT and prostaglandin E2 synthase 1 (PGES-1) inhibitor reestablishes endometrial PGF2α pulses and regresses the CL. In contrast, intrauterine co-administration of IFNT and PGES-1 inhibitor along with intraovarian administration of PGE2 rescues the CL. Together, the accumulating information provides compelling evidence that PGE2 produced by the CL in response to endometrial PGE2 induced by pregnancy may counteract the luteolytic effect of PGF2α as an additional luteoprotective mechanism during MRP or ESP in ruminants. Targeting PGE2 biosynthesis and signaling selectively in the endometrium or CL may provide luteoprotective therapy to improve reproductive efficiency in ruminants.
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Affiliation(s)
- Joe A Arosh
- Reproductive Endocrinology and Cell Signaling Laboratory, Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station 77483.
| | - Sakhila K Banu
- Reproductive Endocrinology and Cell Signaling Laboratory, Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station 77483
| | - John A McCracken
- Department of Animal Science, University of Connecticut, Storrs 06269
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6
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Nelo-Bazán MA, Latorre P, Bolado-Carrancio A, Pérez-Campo FM, Echenique-Robba P, Rodríguez-Rey JC, Carrodeguas JA. Early growth response 1 (EGR-1) is a transcriptional regulator of mitochondrial carrier homolog 1 (MTCH 1)/presenilin 1-associated protein (PSAP). Gene 2015; 578:52-62. [PMID: 26692143 DOI: 10.1016/j.gene.2015.12.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 11/26/2015] [Accepted: 12/07/2015] [Indexed: 01/25/2023]
Abstract
Attempts to elucidate the cellular function of MTCH1 (mitochondrial carrier homolog 1) have not yet rendered a clear insight into the function of this outer mitochondrial membrane protein. Classical biochemical and cell biology approaches have not produced the expected outcome. In vitro experiments have indicated a likely role in the regulation of cell death by apoptosis, and its reported interaction with presenilin 1 suggests a role in the cellular pathways in which this membrane protease participates, nevertheless in vivo data are missing. In an attempt to identify cellular pathways in which this protein might participate, we have studied its promoter looking for transcriptional regulators. We have identified several putative binding sites for EGR-1 (Early growth response 1; a protein involved in growth, proliferation and differentiation), in the proximal region of the MTCH1 promoter. Chromatin immunoprecipitation showed an enrichment of these sequences in genomic DNA bound to EGR-1 and transient overexpression of EGR-1 in cultured HEK293T cells induces an increase of endogenous MTCH1 levels. We also show that MTCH1 levels increase in response to treatment of cells with doxorubicin, an apoptosis inducer through DNA damage. The endogenous levels of MTCH1 decrease when EGR-1 levels are lowered by RNA interference. Our results indicate that EGR-1 is a transcriptional regulator of MTCH1 and give some clues about the cellular processes in which MTCH1 might participate.
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Affiliation(s)
- María Alejandra Nelo-Bazán
- Institute for Biocomputation and Physics of Complex Systems, University of Zaragoza, Zaragoza, Spain; Department of Biochemistry and Molecular and Cellular Biology, University of Zaragoza, Zaragoza, Spain.
| | - Pedro Latorre
- Institute for Biocomputation and Physics of Complex Systems, University of Zaragoza, Zaragoza, Spain; Department of Animal Production and Food Science and Technology, University of Zaragoza, Spain.
| | | | - Flor M Pérez-Campo
- Department of Internal Medicine, Hospital U. Marqués de Valdecilla-IDIVAL University of Cantabria, 39008 Santander, Cantabria, Spain.
| | - Pablo Echenique-Robba
- Institute for Biocomputation and Physics of Complex Systems, University of Zaragoza, Zaragoza, Spain; Instituto de Química Física Rocasolano, CSIC, Madrid, Spain; Zaragoza Scientific Center for Advanced Modeling (ZCAM), Universidad de Zaragoza, Spain; Departamento de Física Teórica, Universidad de Zaragoza, Spain; Unidad Asociada IQFR-BIFI, Madrid-Zaragoza, Spain.
| | | | - José Alberto Carrodeguas
- Institute for Biocomputation and Physics of Complex Systems, University of Zaragoza, Zaragoza, Spain; Department of Biochemistry and Molecular and Cellular Biology, University of Zaragoza, Zaragoza, Spain; Unidad Asociada IQFR-BIFI, Madrid-Zaragoza, Spain.
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7
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Chakraborty PK, Xiong X, Mustafi SB, Saha S, Dhanasekaran D, Mandal NA, McMeekin S, Bhattacharya R, Mukherjee P. Role of cystathionine beta synthase in lipid metabolism in ovarian cancer. Oncotarget 2015; 6:37367-84. [PMID: 26452259 PMCID: PMC4741935 DOI: 10.18632/oncotarget.5424] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 09/24/2015] [Indexed: 12/21/2022] Open
Abstract
Elevated lipid metabolism is implicated in poor survival in ovarian cancer (OC) and other cancers; however, current lipogenesis-targeting strategies lack cancer cell specificity. Here, we identify a novel role of cystathionine beta-synthase (CBS), a sulphur amino acid metabolizing enzyme highly expressed in several ovarian cancer cell lines, in driving deregulated lipid metabolism in OC. We examined the role of CBS in regulation of triglycerides, cholesterol and lipogenic enzymes via the lipogenic transcription factors SREBP1 and SREBP2. CBS silencing attenuated the expression of number of key enzymes involved in lipid synthesis (FASN and ACC1). Additionally CBS abrogates lipid uptake in OC cells. Gene silencing of CBS or SREBPs abrogated cellular migration and invasion in OC, while ectopic expression of SREBPs can rescue phenotypic effects of CBS silencing by restoring cell migration and invasion. Mechanistically, CBS represses SREBP1 and SREBP2 at the transcription levels by modulating the transcription factor Sp1. We further established the roles of both CBS and SREBPs in regulating ovarian tumor growth in vivo. In orthotopic tumor models, CBS or SREBP silencing resulted in reduced tumor cells proliferation, blood vessels formation and lipid content. Hence, cancer-selective disruption of the lipid metabolism pathway is possible by targeting CBS and, at least for OC, promises a profound benefit.
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Affiliation(s)
- Prabir K. Chakraborty
- Department of Pathology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Xunhao Xiong
- Department of Pathology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Soumyajit Banerjee Mustafi
- Department of Obstetrics and Gynecology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Sounik Saha
- Department of Pathology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Danny Dhanasekaran
- Department of Cell Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Nawajes A. Mandal
- Dean A. McGee Eye Institute, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Scott McMeekin
- Department of Obstetrics and Gynecology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
- Peggy and Charles Stephenson Cancer Center, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Resham Bhattacharya
- Department of Obstetrics and Gynecology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
- Peggy and Charles Stephenson Cancer Center, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Priyabrata Mukherjee
- Department of Pathology, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
- Peggy and Charles Stephenson Cancer Center, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
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8
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Yang H, Lee JH, Noh JK, Kim HC, Park CJ, Park JW, Kim KK. Expression Pattern of Early Growth Response Gene 1 during Olive Flounder (Paralichthys olivaceus) Embryonic Development. Dev Reprod 2015; 18:233-40. [PMID: 25949193 PMCID: PMC4415633 DOI: 10.12717/devrep.2014.18.4.233] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 11/17/2014] [Accepted: 11/19/2014] [Indexed: 11/24/2022]
Abstract
The early growth response protein 1 (Egr-1) is a widely reported zinc finger protein and a well known transcription factor encoded by the Egr-1 gene, which plays key roles in many aspects of vertebrate embryogenesis and in adult vertebrates. The Egr-1 expression is important in the formation of the gill vascular system in flounders, which develops during the post-hatching phase and is essential for survival during the juvenile period. However, the complete details of Egr-1 expression during embryo development in olive flounder are not available. We assessed the expression patterns of Egr-1 during the early development of olive flounders by using reverse transcription polymerase chain reaction (RT-PCR) analysis. Microscopic observations showed that gill filament formation corresponded with the Egr-1 expression. Thus, we showed that Egr-1 plays a vital role in angiogenesis in the gill filaments during embryogenesis. Further, Egr-1 expression was found to be strong at 5 days after hatching (DAH), in the development of the gill vascular system, and this strong expression level was maintained throughout all the development stages. Our findings have important implications with respect to the biological role of Egr-1 and evolution of the first respiratory blood vessels in the gills of olive flounder. Further studies are required to elucidate the Egr-1-mediated stress response and to decipher the functional role of Egr-1 in developmental stages.
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Affiliation(s)
- Hyun Yang
- Genetics and Breeding Research Center, NFRDI, Geoje 656-842, Korea
| | - Jeong-Ho Lee
- Genetics and Breeding Research Center, NFRDI, Geoje 656-842, Korea
| | - Jae Koo Noh
- Genetics and Breeding Research Center, NFRDI, Geoje 656-842, Korea
| | - Hyun Chul Kim
- Genetics and Breeding Research Center, NFRDI, Geoje 656-842, Korea
| | - Choul-Ji Park
- Genetics and Breeding Research Center, NFRDI, Geoje 656-842, Korea
| | - Jong-Won Park
- Genetics and Breeding Research Center, NFRDI, Geoje 656-842, Korea
| | - Kyung-Kil Kim
- Genetics and Breeding Research Center, NFRDI, Geoje 656-842, Korea
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9
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Yang H, Lee JH, Noh JK, Kim HC, Park CJ, Park JW, Kim KK. Expression Pattern of Early Growth Response Gene 1 during Olive Flounder ( Paralichthys olivaceus) Embryonic Development. Dev Reprod 2014; 18:233-240. [PMID: 32885106 PMCID: PMC7455093 DOI: 10.12717/dr.2014.18.4.233] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The early growth response protein 1 (Egr-1) is a widely reported zinc finger
protein and a well known transcription factor encoded by the Egr-1 gene, which
plays key roles in many aspects of vertebrate embryogenesis and in adult
vertebrates. The Egr-1 expression is important in the formation of the gill
vascular system in flounders, which develops during the post-hatching phase and
is essential for survival during the juvenile period. However, the complete
details of Egr-1 expression during embryo development in olive flounder are not
available. We assessed the expression patterns of Egr-1 during the early
development of olive flounders by using reverse transcription polymerase chain
reaction (RT-PCR) analysis. Microscopic observations showed that gill filament
formation corresponded with the Egr-1 expression. Thus, we showed that Egr-1
plays a vital role in angiogenesis in the gill filaments during embryogenesis.
Further, Egr-1 expression was found to be strong at 5 days after hatching (DAH),
in the development of the gill vascular system, and this strong expression level
was maintained throughout all the development stages. Our findings have
important implications with respect to the biological role of Egr-1 and
evolution of the first respiratory blood vessels in the gills of olive flounder.
Further studies are required to elucidate the Egr-1-mediated stress response and
to decipher the functional role of Egr-1 in developmental stages.
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Affiliation(s)
- Hyun Yang
- Genetics and Breeding Research Center, NFRDI, Geoje 656-842, Korea
| | - Jeong-Ho Lee
- Genetics and Breeding Research Center, NFRDI, Geoje 656-842, Korea
| | - Jae Koo Noh
- Genetics and Breeding Research Center, NFRDI, Geoje 656-842, Korea
| | - Hyun Chul Kim
- Genetics and Breeding Research Center, NFRDI, Geoje 656-842, Korea
| | - Choul-Ji Park
- Genetics and Breeding Research Center, NFRDI, Geoje 656-842, Korea
| | - Jong-Won Park
- Genetics and Breeding Research Center, NFRDI, Geoje 656-842, Korea
| | - Kyung-Kil Kim
- Genetics and Breeding Research Center, NFRDI, Geoje 656-842, Korea
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10
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Bitter A, Rümmele P, Klein K, Kandel BA, Rieger JK, Nüssler AK, Zanger UM, Trauner M, Schwab M, Burk O. Pregnane X receptor activation and silencing promote steatosis of human hepatic cells by distinct lipogenic mechanisms. Arch Toxicol 2014; 89:2089-103. [PMID: 25182422 DOI: 10.1007/s00204-014-1348-x] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 08/25/2014] [Indexed: 12/20/2022]
Abstract
In addition to its well-characterized role in the regulation of drug metabolism and transport by xenobiotics, pregnane X receptor (PXR) critically impacts on lipid homeostasis. In mice, both ligand-dependent activation and knockout of PXR were previously shown to promote hepatic steatosis. To elucidate the respective pathways in human liver, we generated clones of human hepatoma HepG2 cells exhibiting different PXR protein levels, and analyzed effects of PXR activation and knockdown on steatosis and expression of lipogenic genes. Ligand-dependent activation as well as knockdown of PXR resulted in increased steatosis in HepG2 cells. Activation of PXR induced the sterol regulatory element-binding protein (SREBP) 1-dependent lipogenic pathway via PXR-dependent induction of SREBP1a, which was confirmed in primary human hepatocytes. Inhibiting SREBP1 activity by blocking the cleavage-dependent maturation of SREBP1 protein impaired the induction of lipogenic SREBP1 target genes and triglyceride accumulation by PXR activation. On the other hand, PXR knockdown resulted in up-regulation of aldo-keto reductase (AKR) 1B10, which enhanced the acetyl-CoA carboxylase (ACC)-catalyzed reaction step of de novo lipogenesis. In a cohort of human liver samples histologically classified for non-alcoholic fatty liver disease, AKR1B10, SREBP1a and SREBP1 lipogenic target genes proved to be up-regulated in steatohepatitis, while PXR protein was reduced. In summary, our data suggest that activation and knockdown of PXR in human hepatic cells promote de novo lipogenesis and steatosis by induction of the SREBP1 pathway and AKR1B10-mediated increase of ACC activity, respectively, thus providing mechanistic explanations for a putative dual role of PXR in the pathogenesis of steatohepatitis.
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Affiliation(s)
- Andreas Bitter
- Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Auerbachstrasse 112, 70376, Stuttgart, Germany
| | - Petra Rümmele
- Institute of Pathology, University of Regensburg, Regensburg, Germany
| | - Kathrin Klein
- Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Auerbachstrasse 112, 70376, Stuttgart, Germany
| | - Benjamin A Kandel
- Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Auerbachstrasse 112, 70376, Stuttgart, Germany
| | - Jessica K Rieger
- Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Auerbachstrasse 112, 70376, Stuttgart, Germany
| | - Andreas K Nüssler
- Department of Traumatology, University of Tübingen, Tübingen, Germany
| | - Ulrich M Zanger
- Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Auerbachstrasse 112, 70376, Stuttgart, Germany
| | - Michael Trauner
- Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Matthias Schwab
- Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Auerbachstrasse 112, 70376, Stuttgart, Germany
- Department of Clinical Pharmacology, Institute of Experimental and Clinical Pharmacology and Toxicology, University Hospital, Tübingen, Germany
| | - Oliver Burk
- Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Auerbachstrasse 112, 70376, Stuttgart, Germany.
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Lee J, Stanley JA, McCracken JA, Banu SK, Arosh JA. Intrauterine coadministration of ERK1/2 inhibitor U0126 inhibits interferon TAU action in the endometrium and restores luteolytic PGF2alpha pulses in sheep. Biol Reprod 2014; 91:46. [PMID: 24876409 DOI: 10.1095/biolreprod.113.111872] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
In ruminants, prostaglandin F2 alpha (PGF2alpha) is synthesized and released in a pulsatile pattern from the endometrial luminal epithelial (LE) cells during the process of luteolysis. Interferon tau (IFNT) is a Type 1 IFN secreted by the trophoblast cells of the developing conceptus. IFNT acts locally on endometrial LE cells to inhibit pulsatile releases of PGF2alpha and thus establish an endocrine environment for recognition of pregnancy. Cell signaling pathways through which IFNT stimulates expression of multiple genes or proteins in endometrial LE are largely unknown. Results of the present investigation indicate that intrauterine administration of IFNT inhibits pulsatile release of PGF2alpha, while coadministration IFNT and ERK 1/2 inhibitor U0126 restores luteolytic PGF2alpha pulses in sheep. IFNT increases phosphorylation of ERK1/2 proteins and increases its interaction with PGT proteins in endometrial LE. Blockade of ERK1/2 pathways inhibits IFNT action, decreases pERK1/2 and PGT protein interactions, and re-establishes the spatial expression of the oxytocin receptor protein completely and the estrogen receptor protein partially without modulating the expression of interferon regulatory factor-2 (IRF-2) protein in endometrial LE. IFNT does not decrease expression of COX-2, PGDH, or PGT protein in endometrial LE. Our results provide important new insights into IFNT signaling and the molecular endocrine control of PGF2alpha release at the time of establishment of pregnancy in ruminants. This novel IFNT-ERK1/2 signaling module needs to be explored in future studies to understand molecular and cellular mechanisms of IFNT action in endometrial LE in ruminants.
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Affiliation(s)
- JeHoon Lee
- Reproductive Endocrinology and Cell Signaling Laboratory, Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas
| | - Jone A Stanley
- Reproductive Endocrinology and Cell Signaling Laboratory, Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas
| | - John A McCracken
- Department of Animal Science, University of Connecticut, Storrs, Connecticut
| | - Sakhila K Banu
- Reproductive Endocrinology and Cell Signaling Laboratory, Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas
| | - Joe A Arosh
- Reproductive Endocrinology and Cell Signaling Laboratory, Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas
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12
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Szántó M, Brunyánszki A, Márton J, Vámosi G, Nagy L, Fodor T, Kiss B, Virág L, Gergely P, Bai P. Deletion of PARP-2 induces hepatic cholesterol accumulation and decrease in HDL levels. Biochim Biophys Acta Mol Basis Dis 2013; 1842:594-602. [PMID: 24365238 DOI: 10.1016/j.bbadis.2013.12.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 12/07/2013] [Accepted: 12/13/2013] [Indexed: 12/11/2022]
Abstract
Poly(ADP-ribose) polymerase-2 (PARP-2) is acknowledged as a DNA repair enzyme. However, recent investigations have attributed unique roles to PARP-2 in metabolic regulation in the liver. We assessed changes in hepatic lipid homeostasis upon the deletion of PARP-2 and found that cholesterol levels were higher in PARP-2(-/-) mice as compared to wild-type littermates. To uncover the molecular background, we analyzed changes in steady-state mRNA levels upon the knockdown of PARP-2 in HepG2 cells and in murine liver that revealed higher expression of sterol-regulatory element binding protein (SREBP)-1 dependent genes. We demonstrated that PARP-2 is a suppressor of the SREBP1 promoter, and the suppression of the SREBP1 gene depends on the enzymatic activation of PARP-2. Consequently, the knockdown of PARP-2 enhances SREBP1 expression that in turn induces the genes driven by SREBP1 culminating in higher hepatic cholesterol content. We did not detect hypercholesterolemia, higher fecal cholesterol content or increase in serum LDL, although serum HDL levels decreased in the PARP-2(-/-) mice. In cells and mice where PARP-2 was deleted we observed decreased ABCA1 mRNA and protein expression that is probably linked to lower HDL levels. In our current study we show that PARP-2 impacts on hepatic and systemic cholesterol homeostasis. Furthermore, the depletion of PARP-2 leads to lower HDL levels which represent a risk factor to cardiovascular diseases.
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Affiliation(s)
- Magdolna Szántó
- MTA-DE Cell Biology and Signaling Research Group of the Hungarian Academy of Sciences, 4032 Debrecen, Hungary; Department of Medical Chemistry, University of Debrecen, 4032 Debrecen, Hungary
| | - Attila Brunyánszki
- MTA-DE Cell Biology and Signaling Research Group of the Hungarian Academy of Sciences, 4032 Debrecen, Hungary
| | - Judit Márton
- Department of Medical Chemistry, University of Debrecen, 4032 Debrecen, Hungary
| | - György Vámosi
- Department of Biophysics and Cell Biology, University of Debrecen, 4032 Debrecen, Hungary
| | - Lilla Nagy
- Department of Medical Chemistry, University of Debrecen, 4032 Debrecen, Hungary
| | - Tamás Fodor
- Department of Medical Chemistry, University of Debrecen, 4032 Debrecen, Hungary
| | - Borbála Kiss
- Department of Dermatology, Medical and Health Science Center, University of Debrecen, 4032 Debrecen, Hungary
| | - László Virág
- MTA-DE Cell Biology and Signaling Research Group of the Hungarian Academy of Sciences, 4032 Debrecen, Hungary; Department of Medical Chemistry, University of Debrecen, 4032 Debrecen, Hungary
| | - Pál Gergely
- Department of Medical Chemistry, University of Debrecen, 4032 Debrecen, Hungary
| | - Péter Bai
- MTA-DE Cell Biology and Signaling Research Group of the Hungarian Academy of Sciences, 4032 Debrecen, Hungary; Department of Medical Chemistry, University of Debrecen, 4032 Debrecen, Hungary.
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13
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SREBP-1a activation by HBx and the effect on hepatitis B virus enhancer II/core promoter. Biochem Biophys Res Commun 2013; 432:643-9. [PMID: 23422505 DOI: 10.1016/j.bbrc.2013.02.030] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Accepted: 02/08/2013] [Indexed: 01/12/2023]
Abstract
Hepatitis B virus (HBV) X protein (HBx) plays an important role in HBV pathogenesis by regulating gene expression. Sterol regulatory element binding protein-1a (SREBP-1a) is a key transcriptional factor for modulating fatty acid and cholesterol synthesis. Here we demonstrated that HBx increased mature SREBP-1a protein level in the nucleus and its activity as a transcription factor. We further showed that the up-regulation of SREBP-1a by HBx occurred at the transcriptional level after ectopic expression and in the context of HBV replication. Deletional analysis using SREBP-1a promoter revealed that the sequence from -436 to -398 in the promoter was required for its activation by HBx. This promoter region possesses the binding sequences for two basic leucine zipper (b-ZIP) transcription factors, namely C/EBP and E4BP4. Mutagenesis of the binding sequences on the SREBP-1a promoter and ectopic expression experiments demonstrated that C/EBPα enhanced SREBP-1a activation by HBx, while E4BP4 had an inhibitory effect. C/EBPα was able to significantly reverse the inhibitory activity of E4BP4 on SREBP-1a promoter. These results demonstrated that HBx activates SREBP-1a activity at the transcription level through a complex mechanism involving two bZIP transcription factors C/EBP and E4BP4 with C/EBP being the dominant positive factor. Finally, we showed that knocking down SREBP-1 abolishes HBV enhancer II/core promoter activation by HBx.
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14
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Transcriptional regulation by post-transcriptional modification—Role of phosphorylation in Sp1 transcriptional activity. Gene 2012; 508:1-8. [DOI: 10.1016/j.gene.2012.07.022] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 05/22/2012] [Accepted: 07/16/2012] [Indexed: 01/05/2023]
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15
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Nebbaki SS, El Mansouri FE, Afif H, Kapoor M, Benderdour M, Duval N, Pelletier JP, Martel-Pelletier J, Fahmi H. Egr-1 contributes to IL-1-mediated down-regulation of peroxisome proliferator-activated receptor γ expression in human osteoarthritic chondrocytes. Arthritis Res Ther 2012; 14:R69. [PMID: 22455954 PMCID: PMC3446440 DOI: 10.1186/ar3788] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Revised: 02/17/2012] [Accepted: 03/28/2012] [Indexed: 02/06/2023] Open
Abstract
INTRODUCTION Peroxisome proliferator-activated receptor (PPAR)γ has been shown to exhibit anti-inflammatory and anti-catabolic properties and to be protective in animal models of osteoarthritis (OA). We have previously shown that interleukin-1β (IL-1) down-regulates PPARγ expression in human OA chondrocytes. However, the mechanisms underlying this effect have not been well characterized. The PPARγ promoter harbors an overlapping Egr-1/specificity protein 1 (Sp1) binding site. In this study, our objective was to define the roles of Egr-1 and Sp1 in IL-1-mediated down-regulation of PPARγ expression. METHODS Chondrocytes were stimulated with IL-1 and the expression levels of Egr-1 and Sp1 mRNAs and proteins were evaluated using real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blotting, respectively. The role of de novo protein synthesis was evaluated using the protein synthesis inhibitor cycloheximide (CHX). The recruitment of Sp1 and Egr-1 to the PPARγ promoter was evaluated using chromatin immunoprecipitation (ChIP) assays. The PPARγ promoter activity was analyzed in transient transfection experiments. The roles of Egr-1 and Sp1 were further evaluated using small interfering RNA (siRNA) approaches. The level of Egr-1 in cartilage was determined using immunohistochemistry. RESULTS Down-regulation of PPARγ expression by IL-1 requires de novo protein synthesis and was concomitant with the induction of the transcription factor Egr-1. Treatment with IL-1 induced Egr-1 recruitment and reduced Sp1 occupancy at the PPARγ promoter. Overexpression of Egr-1 potentiated, whereas overexpression of Sp1 alleviated, the suppressive effect of IL-1 on the PPARγ promoter, suggesting that Egr-1 may mediate the suppressive effect of IL-1. Consistently, Egr-1 silencing prevented IL-1-mediated down-regulation of PPARγ expression. We also showed that the level of Egr-1 expression was elevated in OA cartilage compared to normal cartilage. CONCLUSIONS Our results indicate that induction and recruitment of Egr-1 contributed to the suppressive effect of IL-1 on PPARγ expression. They also suggest that modulation of Egr-1 levels in the joint may have therapeutic potential in OA.
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Affiliation(s)
- Sarah-Salwa Nebbaki
- Osteoarthritis Research Unit, Research Centre of the University of Montreal Hospital Center (CR-CHUM), Notre-Dame Hospital, 1560 Sherbrooke Street East, J,A, DeSève Pavillion, Y-2628, and Department of Medicine, University of Montreal, Montreal, QC H2L 4M1, Canada
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16
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Fernández-Alvarez A, Alvarez MS, Gonzalez R, Cucarella C, Muntané J, Casado M. Human SREBP1c expression in liver is directly regulated by peroxisome proliferator-activated receptor alpha (PPARalpha). J Biol Chem 2011; 286:21466-77. [PMID: 21540177 DOI: 10.1074/jbc.m110.209973] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Sterol regulatory element binding proteins (SREBPs) regulate the expression of a number of enzymes, which catalyze the synthesis of fatty acids, cholesterol, triglycerides, and phospholipids. SREBP1c is the most relevant isoform in the adult liver, and its expression is controlled by the nutritional state. Transcriptional regulation studies into the SREBP1c gene, performed in the last few years, have improved our knowledge of the variability of signals that converge on its promoter region. Insulin, cholesterol derivatives, T3 and other endogenous molecules have been demonstrated to regulate the SREBP1c expression, particularly in rodents. The present study aimed to perform a detailed analysis of the human SREBP1c gene promoter structure in liver cells by focusing on responses to diverse metabolic signals. Serial deletion and mutation assays reveal that both SREBP (SRE) and LXR (LXRE) response elements are involved in SREBP1c transcription regulation mediated by insulin and cholesterol derivatives. We discovered that peroxisome proliferation-activated receptor alpha (PPARα) agonists enhance the activity of the SREBP1c promoter; a DR1 element, at -453 in the human promoter was involved in this activation. Moreover, PPARα agonists act in cooperation with LXR or insulin to induce lipogenesis. Collectively, our results identify PPARα as a novel regulatory factor in SREBP1c regulation which plays a relevant role in the interplay between lipids and insulin metabolic regulation.
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Affiliation(s)
- Ana Fernández-Alvarez
- Instituto de Biomedicina de Valencia, IBV-CSIC, Jaime Roig 11, 46010 Valencia, Spain
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17
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Banu SK, Lee J, Stephen SD, Nithy TK, Arosh JA. Interferon tau regulates PGF2alpha release from the ovine endometrial epithelial cells via activation of novel JAK/EGFR/ERK/EGR-1 pathways. Mol Endocrinol 2010; 24:2315-30. [PMID: 20962043 DOI: 10.1210/me.2010-0205] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
In ruminants, pulsatile release of prostaglandin F2α (PGF(2α)) from the endometrium is transported to the ovary and induces luteolysis thereby allowing new estrous cycle. Interferon tau (IFNT), a type 1 IFN secreted by the trophoblast cells of the developing conceptus, acts on endometrial luminal epithelial (LE) cells and inhibits pulsatile release of PGF(2α) and establishes pregnancy. One of the unknown mechanisms is that endometrial pulsatile release of PGF(2α) is inhibited whereas basal release of PGF(2α) is increased in pregnant compared with nonpregnant sheep. We have recently found that pulsatile release of PGF(2α) from the endometrium is regulated by prostaglandin transporter (PGT)-mediated mechanisms. We hypothesize that modulation in the endometrial pulsatile vs. basal release of PGF(2α) likely requires PGT-mediated selective transport, and IFNT interacts with PGT protein and modulates pulsatile vs. basal release of PGF(2α). The new findings of the present study are: 1) IFNT activates novel JAK-SRC kinase-EGFR-RAS-RAF-ERK1/2-early growth response (EGR)-1 signaling module in LE cells; 2) IFNT increases interactions between PGT and ERK1/2 or EGR-1 proteins and alters phosphorylation of PGT protein; 3) IFNT precludes action of protein kinase C and Ca(2+) on PGT function; and 4) IFNT inhibits 80% PGT-mediated but not 20% simple diffusion-mediated release of PGF(2α) from the endometrial LE cells through this novel signaling module. The results of the present study provide important new insights on IFNT signaling and molecular control of PGT-mediated release of PGF(2α) and unravel the underlying mechanisms responsible for the increased basal release of PGF(2α) at the time of establishment of pregnancy in ruminants.
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Affiliation(s)
- Sakhila K Banu
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas 77843, USA
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18
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Fernández-Alvarez A, Soledad Alvarez M, Cucarella C, Casado M. Characterization of the human insulin-induced gene 2 (INSIG2) promoter: the role of Ets-binding motifs. J Biol Chem 2010; 285:11765-74. [PMID: 20145255 DOI: 10.1074/jbc.m109.067447] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin-induced gene 2 (INSIG2) and its homolog INSIG1 encode closely related endoplasmic reticulum proteins that regulate the proteolytic activation of sterol regulatory element-binding proteins, transcription factors that activate the synthesis of cholesterol and fatty acids in animal cells. Several studies have been carried out to identify INSIG2 genetic variants associated with metabolic diseases. However, few data have been published regarding the regulation of INSIG2 gene expression. Two Insig2 transcripts have been described in rodents through the use of different promoters that produce different noncoding first exons that splice into a common second exon. Herein we report the cloning and characterization of the human INSIG2 promoter and the detection of an INSIG2-specific transcript homologous to the Insig2b mouse variant in human liver. Deletion analyses on 3 kb of 5'-flanking DNA of the human INSIG2 gene revealed the functional importance of a 350-bp region upstream of the transcription start site. Mutated analyses, chromatin immunoprecipitation assays, and RNA interference analyses unveiled the significance of an Ets-consensus motif in the proximal region and the interaction of the Ets family member SAP1a (serum response factor (SRF) accessory protein-1a) with this region of the human INSIG2 promoter. Moreover, our findings suggest that insulin activated the human INSIG2 promoter in a process mediated by phosphorylated SAP1a. Overall, these results map the functional elements in the human INSIG2 promoter sequence and suggest an unexpected regulation of INSIG2 gene expression in human liver.
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Affiliation(s)
- Ana Fernández-Alvarez
- Instituto de Biomedicina de Valencia (Consejo Superior de Investigaciones Científicas), Valencia, Spain
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Liu QF, Yu HW, Liu GN. Egr-1 upregulates OPN through direct binding to its promoter and OPN upregulates Egr-1 via the ERK pathway. Mol Cell Biochem 2009; 332:77-84. [DOI: 10.1007/s11010-009-0176-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Accepted: 06/09/2009] [Indexed: 11/29/2022]
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Korade Z, Kenworthy AK, Mirnics K. Molecular consequences of altered neuronal cholesterol biosynthesis. J Neurosci Res 2009; 87:866-75. [PMID: 18951487 DOI: 10.1002/jnr.21917] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The first dedicated step in de novo cholesterol biosynthesis begins with formation of squalene and ends with the reduction of 7-dehydrocholesterol by 7-dehydrocholesterol reductase (Dhcr7) into cholesterol, which is an essential structural and signaling molecule. Mutations in the Dhcr7 gene lead to Smith-Lemli-Opitz syndrome (SLOS), which is characterized by developmental deformities, incomplete myelination, and mental retardation. To understand better the molecular consequences of Dhcr7 deficiency in neuronal tissue, we analyzed the effect of cholesterol deficiency on the transcriptome in Neuro2a cells. Transient down-regulation of Dhcr7 by siRNA led to altered expression of multiple molecules that play critical roles in intracellular signaling or vesicular transport or are inserted into membrane rafts (e.g. Egr1, Snx, and Adam19). A similar down-regulation was also observed in stable Dhrc7-shRNA-transfected cell lines, and the findings were verified by qPCR. Furthermore, we investigated the Dhcr7-deficient and control cells for the expression of several critical genes involved in lipid biosynthesis. Among these, fatty acid synthase, sterol-regulatory element binding protein 2, SREBF chaperone, site-1 protease, and squalene synthase showed a significant down-regulation, suggesting that, in a neuronal cell line, Dhcr7 is a potent regulator of lipid biosynthesis. Importantly, the gene expression changes were present in both lipid-containing and cholesterol-deficient media, suggesting that intrinsic cholesterol biosynthesis is necessary for normal neuronal function and cannot be supplemented from extrinsic sources.
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Affiliation(s)
- Zeljka Korade
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee 37232, USA.
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