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Maruyama R, Kudo Y, Sugiyama T. A new strategy for screening novel functional genes involved in reduction of lipid droplet accumulation. Biofactors 2024; 50:467-476. [PMID: 37983968 DOI: 10.1002/biof.2019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 10/30/2023] [Indexed: 11/22/2023]
Abstract
Lipid droplets (LDs) are organelles that store excess lipids and provide fatty acids for energy production during starvation. LDs are also essential for cellular maintenance, but excessive accumulation of LDs triggers various cancers in addition to metabolic diseases such as diabetes. In this study, we aimed to develop a strategy to identify new genes that reduces accumulation of LDs in cancer cells using an RNA interference (RNAi) screening system employing artificial sequence-enriched shRNA libraries. Monitoring LDs by fluorescent activated cell sorting, the subsequently collected cumulative LDs cells, and shRNA sequence analysis identified a clone that potentially functioned to accumulate LDs. The clone showed no identical sequence to human Refseq. It showed very similar sequence to seven genes by allowing three mismatches. Among these genes, we identified the mediator complex subunit 6 (MED6) gene as a target of this shRNA. Silencing of MED6 led to an increase in LD accumulation and expression of the marker genes, PLIN2 and DGAT1, in fatty cells. MED6 is a member of the mediator complex that regulates RNA polymerase II transcription through transcription factor II. Some mediator complexes play important roles in both normal and pathophysiological transcription processes. These results suggest that MED6 transcriptionally regulates the genes involved in lipid metabolism and suppresses LD accumulation.
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Affiliation(s)
- Ryuto Maruyama
- Graduate School of Bionics, Tokyo University of Technology, Tokyo, Japan
- Department of Life Science, Rikkyo University, Tokyo, Japan
| | - Yasuhiro Kudo
- Graduate School of Bionics, Tokyo University of Technology, Tokyo, Japan
| | - Tomoyasu Sugiyama
- Graduate School of Bionics, Tokyo University of Technology, Tokyo, Japan
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2
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Sekine H, Motohashi H. Unique and overlapping roles of NRF2 and NRF1 in transcriptional regulation. J Clin Biochem Nutr 2024; 74:91-96. [PMID: 38510688 PMCID: PMC10948342 DOI: 10.3164/jcbn.23-106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 11/18/2023] [Indexed: 03/22/2024] Open
Abstract
Transcription is regulated by specific transcription factors that mediate signaling in response to extrinsic and intrinsic stimuli such as nutrients, hormones, and oxidative stresses. Many transcription factors are grouped based on their highly conserved DNA binding domains. Consequently, transcription factors within the same family often exhibit functional redundancy and compensation. NRF2 (NFE2L2) and NRF1 (NFE2L1) belong to the CNC family transcription factors, which are responsible for various stress responses. Although their DNA binding properties are strikingly similar, NRF2 and NRF1 are recognized to play distinct roles in a cell by mediating responses to oxidative stress and proteotoxic stress, respectively. In this review, we here overview the distinct and shared roles of NRF2 and NRF1 in the transcriptional regulation of target genes, with a particular focus on the nuclear protein binding partners associated with each factor.
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Affiliation(s)
- Hiroki Sekine
- Department of Gene Expression Regulation, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-cho, Aoba-ku, Sendai, Miyagi 980-8575, Japan
| | - Hozumi Motohashi
- Department of Gene Expression Regulation, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-cho, Aoba-ku, Sendai, Miyagi 980-8575, Japan
- Department of Medical Biochemistry, Tohoku University Graduate School of Medicine, 2-1 Seiryo-cho, Aoba-ku, Sendai, Miyagi 980-8575, Japan
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3
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Tang S, Li R, Ma W, Lian L, Gao J, Cao Y, Gan L. Cardiac-to-adipose axis in metabolic homeostasis and diseases: special instructions from the heart. Cell Biosci 2023; 13:161. [PMID: 37667400 PMCID: PMC10476430 DOI: 10.1186/s13578-023-01097-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 07/30/2023] [Indexed: 09/06/2023] Open
Abstract
Adipose tissue is essential for maintaining systemic metabolic homeostasis through traditional metabolic regulation, endocrine crosstalk, and extracellular vesicle production. Adipose dysfunction is a risk factor for cardiovascular diseases. The heart is a traditional pump organ. However, it has recently been recognized to coordinate interorgan cross-talk by providing peripheral signals known as cardiokines. These molecules include specific peptides, proteins, microRNAs and novel extracellular vesicle-carried cargoes. Current studies have shown that generalized cardiokine-mediated adipose regulation affects systemic metabolism. Cardiokines regulate lipolysis, adipogenesis, energy expenditure, thermogenesis during cold exposure and adipokine production. Moreover, cardiokines participate in pathological processes such as obesity, diabetes and ischemic heart injury. The underlying mechanisms of the cardiac-to-adipose axis mediated by cardiokines will be further discussed to provide potential therapeutic targets for metabolic diseases and support a new perspective on the need to correct adipose dysfunction after ischemic heart injury.
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Affiliation(s)
- Songling Tang
- Department of Emergency Medicine and Laboratory of Emergency Medicine, West China Hospital, West China School of Medicine, Sichuan University Chengdu, Chengdu, 610041, People's Republic of China
| | - Ruixin Li
- Department of Emergency Medicine and Laboratory of Emergency Medicine, West China Hospital, West China School of Medicine, Sichuan University Chengdu, Chengdu, 610041, People's Republic of China
| | - Wen Ma
- Sichuan University-The Hong Kong Polytechnic University Institute for Disaster Management and Reconstruction, Chengdu, China
| | - Liu Lian
- Department of Emergency Medicine and Laboratory of Emergency Medicine, West China Hospital, West China School of Medicine, Sichuan University Chengdu, Chengdu, 610041, People's Republic of China
| | - Jiuyu Gao
- Department of Emergency Medicine and Laboratory of Emergency Medicine, West China Hospital, West China School of Medicine, Sichuan University Chengdu, Chengdu, 610041, People's Republic of China
| | - Yu Cao
- Department of Emergency Medicine and Laboratory of Emergency Medicine, West China Hospital, West China School of Medicine, Sichuan University Chengdu, Chengdu, 610041, People's Republic of China.
- Sichuan University-The Hong Kong Polytechnic University Institute for Disaster Management and Reconstruction, Chengdu, China.
| | - Lu Gan
- Department of Emergency Medicine and Laboratory of Emergency Medicine, West China Hospital, West China School of Medicine, Sichuan University Chengdu, Chengdu, 610041, People's Republic of China.
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4
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Richter WF, Nayak S, Iwasa J, Taatjes DJ. The Mediator complex as a master regulator of transcription by RNA polymerase II. Nat Rev Mol Cell Biol 2022; 23:732-749. [PMID: 35725906 PMCID: PMC9207880 DOI: 10.1038/s41580-022-00498-3] [Citation(s) in RCA: 57] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/17/2022] [Indexed: 02/08/2023]
Abstract
The Mediator complex, which in humans is 1.4 MDa in size and includes 26 subunits, controls many aspects of RNA polymerase II (Pol II) function. Apart from its size, a defining feature of Mediator is its intrinsic disorder and conformational flexibility, which contributes to its ability to undergo phase separation and to interact with a myriad of regulatory factors. In this Review, we discuss Mediator structure and function, with emphasis on recent cryogenic electron microscopy data of the 4.0-MDa transcription preinitiation complex. We further discuss how Mediator and sequence-specific DNA-binding transcription factors enable enhancer-dependent regulation of Pol II function at distal gene promoters, through the formation of molecular condensates (or transcription hubs) and chromatin loops. Mediator regulation of Pol II reinitiation is also discussed, in the context of transcription bursting. We propose a working model for Mediator function that combines experimental results and theoretical considerations related to enhancer-promoter interactions, which reconciles contradictory data regarding whether enhancer-promoter communication is direct or indirect. We conclude with a discussion of Mediator's potential as a therapeutic target and of future research directions.
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Affiliation(s)
- William F Richter
- Department of Biochemistry, University of Colorado, Boulder, CO, USA
| | - Shraddha Nayak
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Janet Iwasa
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Dylan J Taatjes
- Department of Biochemistry, University of Colorado, Boulder, CO, USA.
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5
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Vomhof-DeKrey EE, Singhal S, Singhal SK, Stover AD, Rajpathy O, Preszler E, Garcia L, Basson MD. RNA Sequencing of Intestinal Enterocytes Pre- and Post-Roux-en-Y Gastric Bypass Reveals Alteration in Gene Expression Related to Enterocyte Differentiation, Restitution, and Obesity with Regulation by Schlafen 12. Cells 2022; 11:3283. [PMID: 36291149 PMCID: PMC9601224 DOI: 10.3390/cells11203283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 10/10/2022] [Accepted: 10/14/2022] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND The intestinal lining renews itself in a programmed fashion that can be affected by adaptation to surgical procedures such as gastric bypass. METHODS To assess adaptive mechanisms in the human intestine after Roux-en-Y gastric bypass (RYGB), we biopsied proximal jejunum at the anastomotic site during surgery to establish a baseline and endoscopically re-biopsied the same area 6-9 months after bypass for comparison. Laser microdissection was performed on pre- and post-RYGB biopsies to isolate enterocytes for RNA sequencing. RESULTS RNA sequencing suggested significant decreases in gene expression associated with G2/M DNA damage checkpoint regulation of the cell cycle pathway, and significant increases in gene expression associated with the CDP-diacylglycerol biosynthesis pathway TCA cycle II pathway, and pyrimidine ribonucleotide salvage pathway after RYGB. Since Schlafen 12 (SLFN12) is reported to influence enterocytic differentiation, we stained mucosa for SLFN12 and observed increased SLFN12 immunoreactivity. We investigated SLFN12 overexpression in HIEC-6 and FHs 74 Int intestinal epithelial cells and observed similar increased expression of the following genes that were also increased after RYGB: HES2, CARD9, SLC19A2, FBXW7, STXBP4, SPARCL1, and UTS. CONCLUSIONS Our data suggest that RYGB promotes SLFN12 protein expression, cellular mechanism and replication pathways, and genes associated with differentiation and restitution (HES2, CARD9, SLC19A2), as well as obesity-related genes (FBXW7, STXBP4, SPARCL1, UTS).
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Affiliation(s)
- Emilie E. Vomhof-DeKrey
- Department of Surgery, School of Medicine and the Health Sciences, University of North Dakota, Grand Forks, ND 58202, USA
- Department of Biomedical Sciences, School of Medicine and the Health Sciences, University of North Dakota, Grand Forks, ND 58202, USA
| | - Sonalika Singhal
- Department of Pathology, School of Medicine and the Health Sciences, University of North Dakota, Grand Forks, ND 58202, USA
| | - Sandeep K. Singhal
- Department of Pathology, School of Medicine and the Health Sciences, University of North Dakota, Grand Forks, ND 58202, USA
| | - Allie D. Stover
- Department of Biomedical Sciences, School of Medicine and the Health Sciences, University of North Dakota, Grand Forks, ND 58202, USA
| | - Odele Rajpathy
- Department of Biomedical Sciences, School of Medicine and the Health Sciences, University of North Dakota, Grand Forks, ND 58202, USA
| | - Elizabeth Preszler
- Department of Biomedical Sciences, School of Medicine and the Health Sciences, University of North Dakota, Grand Forks, ND 58202, USA
| | - Luis Garcia
- Sanford Health Clinic, Sioux Falls, ND 57117, USA
| | - Marc D. Basson
- Department of Surgery, School of Medicine and the Health Sciences, University of North Dakota, Grand Forks, ND 58202, USA
- Department of Biomedical Sciences, School of Medicine and the Health Sciences, University of North Dakota, Grand Forks, ND 58202, USA
- Department of Pathology, School of Medicine and the Health Sciences, University of North Dakota, Grand Forks, ND 58202, USA
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6
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Song Z, Xiaoli AM, Li Y, Siqin G, Wu T, Strich R, Pessin JE, Yang F. The conserved Mediator subunit cyclin C (CCNC) is required for brown adipocyte development and lipid accumulation. Mol Metab 2022; 64:101548. [PMID: 35863637 PMCID: PMC9386464 DOI: 10.1016/j.molmet.2022.101548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 07/05/2022] [Accepted: 07/11/2022] [Indexed: 01/05/2023] Open
Abstract
OBJECTIVE Cyclin C (CCNC) is the most conserved subunit of the Mediator complex, which is an important transcription cofactor. Recently, we have found that CCNC facilitates brown adipogenesis in vitro by activating C/EBPα-dependent transcription. However, the role of CCNC in brown adipose tissue (BAT) in vivo remains unclear. METHODS We generated conditional knock-out mice by crossing Ccncflox/flox mice with Myf5Cre, Ucp1Cre or AdipoqCre transgenic mice to investigate the role of CCNC in BAT development and function. We applied glucose and insulin tolerance test, cold exposure and indirect calorimetry to capture the physiological phenotypes and used immunostaining, immunoblotting, qRT-PCR, RNA-seq and cell culture to elucidate the underlying mechanisms. RESULTS Here, we show that deletion of CCNC in Myf5+ progenitor cells caused BAT paucity, despite the fact that there was significant neonatal lethality. Mechanistically different from in vitro, CCNC deficiency impaired the proliferation of embryonic brown fat progenitor cells without affecting brown adipogenesis or cell death. Interestingly, CCNC deficiency robustly reduced age-dependent lipid accumulation in differentiated brown adipocytes in all three mouse models. Mechanistically, CCNC in brown adipocytes is required for lipogenic gene expression through the activation of the C/EBPα/GLUT4/ChREBP axis. Consistent with the importance of de novo lipogenesis under carbohydrate-rich diets, high-fat diet (HFD) feeding abolished CCNC deficiency -caused defects of lipid accumulation in BAT. Although insulin sensitivity and response to acute cold exposure were not affected, CCNC deficiency in Ucp1+ cells enhanced the browning of white adipose tissue (beiging) upon prolonged cold exposure. CONCLUSIONS Together, these data indicate an important role of CCNC-Mediator in the regulation of BAT development and lipid accumulation in brown adipocytes.
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Affiliation(s)
- Ziyi Song
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, 530004, China; Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Norman Fleischer Institute for Diabetes and Metabolism, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Alus M Xiaoli
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Norman Fleischer Institute for Diabetes and Metabolism, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
| | - Youlei Li
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Norman Fleischer Institute for Diabetes and Metabolism, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Gerile Siqin
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Norman Fleischer Institute for Diabetes and Metabolism, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Tian Wu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Animal Science and Technology, Guangxi University, Nanning, 530004, China
| | - Randy Strich
- Department of Molecular Biology, Rowan University School of Osteopathic Medicine, Stratford, NJ, 08055, USA
| | - Jeffrey E Pessin
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Norman Fleischer Institute for Diabetes and Metabolism, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Fajun Yang
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Norman Fleischer Institute for Diabetes and Metabolism, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
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7
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Sertori R, Lin JX, Martinez E, Rana S, Sharo A, Kazemian M, Sunderam U, Andrake M, Shinton S, Truong B, Dunbrack RM, Liu C, Srinivasan R, Brenner SE, Seroogy CM, Puck JM, Leonard WJ, Wiest DL. Investigation of the causal etiology in a patient with T-B+NK+ immunodeficiency. Front Immunol 2022; 13:928252. [PMID: 35967429 PMCID: PMC9372720 DOI: 10.3389/fimmu.2022.928252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 06/27/2022] [Indexed: 11/24/2022] Open
Abstract
Newborn screening for severe combined immunodeficiency (SCID) has not only accelerated diagnosis and improved treatment for affected infants, but also led to identification of novel genes required for human T cell development. A male proband had SCID newborn screening showing very low T cell receptor excision circles (TRECs), a biomarker for thymic output of nascent T cells. He had persistent profound T lymphopenia, but normal numbers of B and natural killer (NK) cells. Despite an allogeneic hematopoietic stem cell transplant from his brother, he failed to develop normal T cells. Targeted resequencing excluded known SCID genes; however, whole exome sequencing (WES) of the proband and parents revealed a maternally inherited X-linked missense mutation in MED14 (MED14V763A), a component of the mediator complex. Morpholino (MO)-mediated loss of MED14 function attenuated T cell development in zebrafish. Moreover, this arrest was rescued by ectopic expression of cDNA encoding the wild type human MED14 ortholog, but not by MED14V763A , suggesting that the variant impaired MED14 function. Modeling of the equivalent mutation in mouse (Med14V769A) did not disrupt T cell development at baseline. However, repopulation of peripheral T cells upon competitive bone marrow transplantation was compromised, consistent with the incomplete T cell reconstitution experienced by the proband upon transplantation with bone marrow from his healthy male sibling, who was found to have the same MED14V763A variant. Suspecting that the variable phenotypic expression between the siblings was influenced by further mutation(s), we sought to identify genetic variants present only in the affected proband. Indeed, WES revealed a mutation in the L1 cell adhesion molecule (L1CAMQ498H); however, introducing that mutation in vivo in mice did not disrupt T cell development. Consequently, immunodeficiency in the proband may depend upon additional, unidentified gene variants.
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Affiliation(s)
- Robert Sertori
- Blood Cell Development and Function Program, Fox Chase Cancer Center, Philadelphia, PA, United States
| | - Jian-Xin Lin
- Laboratory of Molecular Immunology, Immunology Center, National Heart, Lung, and Blood Institute, National Institutes of Health (NIH), Bethesda, MD, United States
| | - Esteban Martinez
- Blood Cell Development and Function Program, Fox Chase Cancer Center, Philadelphia, PA, United States
| | - Sadhna Rana
- Innovation Labs, Tata Consultancy Services, Hyderabad, India
| | - Andrew Sharo
- Center for Computational Biology, University of California, Berkeley, CA, United States
| | - Majid Kazemian
- Departments of Biochemistry and Computer Science, Purdue University, West Lafayette, IN, United States
| | - Uma Sunderam
- Innovation Labs, Tata Consultancy Services, Hyderabad, India
| | - Mark Andrake
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA, United States
| | - Susan Shinton
- Blood Cell Development and Function Program, Fox Chase Cancer Center, Philadelphia, PA, United States
| | - Billy Truong
- Blood Cell Development and Function Program, Fox Chase Cancer Center, Philadelphia, PA, United States
| | - Roland M. Dunbrack
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA, United States
| | - Chengyu Liu
- Transgenic Core, National Heart, Lung, and Blood Institute, National Institutes of Health (NIH), Bethesda, MD, United States
| | | | - Steven E. Brenner
- Center for Computational Biology, University of California, Berkeley, CA, United States
| | - Christine M. Seroogy
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI, United States
| | - Jennifer M. Puck
- Department of Pediatrics, University of California San Francisco and UCSF Benioff Children’s Hospital, San Francisco, CA, United States
| | - Warren J. Leonard
- Laboratory of Molecular Immunology, Immunology Center, National Heart, Lung, and Blood Institute, National Institutes of Health (NIH), Bethesda, MD, United States
| | - David L. Wiest
- Blood Cell Development and Function Program, Fox Chase Cancer Center, Philadelphia, PA, United States
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8
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Dacic M, Shibu G, Rogatsky I. Physiological Convergence and Antagonism Between GR and PPARγ in Inflammation and Metabolism. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1390:123-141. [PMID: 36107316 DOI: 10.1007/978-3-031-11836-4_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Nuclear receptors (NRs) are transcription factors that modulate gene expression in a ligand-dependent manner. The ubiquitously expressed glucocorticoid receptor (GR) and peroxisome proliferator-activated receptor gamma (PPARγ) represent steroid (type I) and non-steroid (type II) classes of NRs, respectively. The diverse transcriptional and physiological outcomes of their activation are highly tissue-specific. For example, in subsets of immune cells, such as macrophages, the signaling of GR and PPARγ converges to elicit an anti-inflammatory phenotype; in contrast, in the adipose tissue, their signaling can lead to reciprocal metabolic outcomes. This review explores the cooperative and divergent outcomes of GR and PPARγ functions in different cell types and tissues, including immune cells, adipose tissue and the liver. Understanding the coordinated control of these NR pathways should advance studies in the field and potentially pave the way for developing new therapeutic approaches to exploit the GR:PPARγ crosstalk.
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Affiliation(s)
- Marija Dacic
- Hospital for Special Surgery Research Institute, The David Rosenzweig Genomics Center, New York, NY, USA
- Graduate Program in Physiology, Biophysics and Systems Biology, Weill Cornell Graduate School of Medical Sciences, New York, NY, USA
| | - Gayathri Shibu
- Hospital for Special Surgery Research Institute, The David Rosenzweig Genomics Center, New York, NY, USA
- Graduate Program in Immunology and Microbial Pathogenesis, Weill Cornell Graduate School of Medical Sciences, New York, NY, USA
| | - Inez Rogatsky
- Hospital for Special Surgery Research Institute, The David Rosenzweig Genomics Center, New York, NY, USA.
- Graduate Program in Immunology and Microbial Pathogenesis, Weill Cornell Graduate School of Medical Sciences, New York, NY, USA.
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Tang WS, Weng L, Wang X, Liu CQ, Hu GS, Yin ST, Tao Y, Hong NN, Guo H, Liu W, Wang HR, Zhao TJ. The Mediator subunit MED20 organizes the early adipogenic complex to promote development of adipose tissues and diet-induced obesity. Cell Rep 2021; 36:109314. [PMID: 34233190 DOI: 10.1016/j.celrep.2021.109314] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 04/17/2021] [Accepted: 06/06/2021] [Indexed: 02/07/2023] Open
Abstract
MED20 is a non-essential subunit of the transcriptional coactivator Mediator complex, but its physiological function remains largely unknown. Here, we identify MED20 as a substrate of the anti-obesity CRL4-WDTC1 E3 ubiquitin ligase complex through affinity purification and candidate screening. Overexpression of WDTC1 leads to degradation of MED20, whereas depletion of WDTC1 or CUL4A/B causes accumulation of MED20. Depleting MED20 inhibits adipogenesis, and a non-degradable MED20 mutant restores adipogenesis in WDTC1-overexpressing cells. Furthermore, knockout of Med20 in preadipocytes abolishes development of brown adipose tissues. Removing one allele of Med20 in preadipocytes protects mice from diet-induced obesity and reverses weight gain in Cul4a- or Cul4b-depleted mice. Chromatin immunoprecipitation sequencing (ChIP-seq) analysis reveals that MED20 organizes the early adipogenic complex by bridging C/EBPβ and RNA polymerase II to promote transcription of the central adipogenic factor, PPARγ. Our findings have thus uncovered a critical role of MED20 in promoting adipogenesis, development of adipose tissue and diet-induced obesity.
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Affiliation(s)
- Wen-Shuai Tang
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Li Weng
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Xu Wang
- Shanghai Key Laboratory of Metabolic Remodeling and Disease, Zhongshan Hospital, Institute of Metabolism and Integrative Biology, Fudan University, Shanghai, China; Shanghai Qi Zhi Institute, Shanghai, China
| | - Chang-Qin Liu
- Department of Endocrinology and Diabetes, the First Affiliated Hospital, Xiamen University, Xiamen, Fujian, China
| | - Guo-Sheng Hu
- School of Pharmaceutical Sciences, Fujian Provincial Key Laboratory of Innovative Drug Target Research, Xiamen University, Xiamen, Fujian, China
| | - Shu-Ting Yin
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Ying Tao
- Shanghai Key Laboratory of Metabolic Remodeling and Disease, Zhongshan Hospital, Institute of Metabolism and Integrative Biology, Fudan University, Shanghai, China
| | - Ni-Na Hong
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Huiling Guo
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Wen Liu
- School of Pharmaceutical Sciences, Fujian Provincial Key Laboratory of Innovative Drug Target Research, Xiamen University, Xiamen, Fujian, China
| | - Hong-Rui Wang
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Tong-Jin Zhao
- Shanghai Key Laboratory of Metabolic Remodeling and Disease, Zhongshan Hospital, Institute of Metabolism and Integrative Biology, Fudan University, Shanghai, China; Shanghai Qi Zhi Institute, Shanghai, China.
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10
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Ito K, Schneeberger M, Gerber A, Jishage M, Marchildon F, Maganti AV, Cohen P, Friedman JM, Roeder RG. Critical roles of transcriptional coactivator MED1 in the formation and function of mouse adipose tissues. Genes Dev 2021; 35:729-748. [PMID: 33888560 PMCID: PMC8091968 DOI: 10.1101/gad.346791.120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Accepted: 03/16/2021] [Indexed: 01/12/2023]
Abstract
In this study, Ito et al. sought to understand the precise roles of MED1, and its various domains, at various stages of adipogenesis and in adipose tissue. Using multiple genetic approaches to assess requirements for MED1 in adipocyte formation and function in mice, they show that MED1 is indeed essential for the differentiation and/or function of both brown and white adipocytes, as its absence in these cells leads to, respectively, defective brown fat function and lipodystrophy. The MED1 subunit has been shown to mediate ligand-dependent binding of the Mediator coactivator complex to multiple nuclear receptors, including the adipogenic PPARγ, and to play an essential role in ectopic PPARγ-induced adipogenesis of mouse embryonic fibroblasts. However, the precise roles of MED1, and its various domains, at various stages of adipogenesis and in adipose tissue have been unclear. Here, after establishing requirements for MED1, including specific domains, for differentiation of 3T3L1 cells and both primary white and brown preadipocytes, we used multiple genetic approaches to assess requirements for MED1 in adipocyte formation, maintenance, and function in mice. We show that MED1 is indeed essential for the differentiation and/or function of both brown and white adipocytes, as its absence in these cells leads to, respectively, defective brown fat function and lipodystrophy. This work establishes MED1 as an essential transcriptional coactivator that ensures homeostatic functions of adipocytes.
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Affiliation(s)
- Keiichi Ito
- Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, New York, New York 10065, USA
| | - Marc Schneeberger
- Laboratory of Molecular Genetics, The Rockefeller University, New York, New York 10065, USA
| | - Alan Gerber
- Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, New York, New York 10065, USA
| | - Miki Jishage
- Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, New York, New York 10065, USA
| | - Francois Marchildon
- Laboratory of Molecular Metabolism, The Rockefeller University, New York, New York 10065, USA
| | - Aarthi V Maganti
- Laboratory of Molecular Metabolism, The Rockefeller University, New York, New York 10065, USA
| | - Paul Cohen
- Laboratory of Molecular Metabolism, The Rockefeller University, New York, New York 10065, USA
| | - Jeffrey M Friedman
- Laboratory of Molecular Genetics, The Rockefeller University, New York, New York 10065, USA
| | - Robert G Roeder
- Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, New York, New York 10065, USA
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11
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Abdella R, Talyzina A, Chen S, Inouye CJ, Tjian R, He Y. Structure of the human Mediator-bound transcription preinitiation complex. Science 2021; 372:52-56. [PMID: 33707221 PMCID: PMC8117670 DOI: 10.1126/science.abg3074] [Citation(s) in RCA: 79] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 03/03/2021] [Indexed: 12/24/2022]
Abstract
Eukaryotic transcription requires the assembly of a multisubunit preinitiation complex (PIC) composed of RNA polymerase II (Pol II) and the general transcription factors. The coactivator Mediator is recruited by transcription factors, facilitates the assembly of the PIC, and stimulates phosphorylation of the Pol II C-terminal domain (CTD) by the TFIIH subunit CDK7. Here, we present the cryo-electron microscopy structure of the human Mediator-bound PIC at a resolution below 4 angstroms. Transcription factor binding sites within Mediator are primarily flexibly tethered to the tail module. CDK7 is stabilized by multiple contacts with Mediator. Two binding sites exist for the Pol II CTD, one between the head and middle modules of Mediator and the other in the active site of CDK7, providing structural evidence for Pol II CTD phosphorylation within the Mediator-bound PIC.
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Affiliation(s)
- R Abdella
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
- Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL, USA
| | - A Talyzina
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
- Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL, USA
| | - S Chen
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
- Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL, USA
| | - C J Inouye
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
- Li Ka Shing Center for Biomedical and Health Sciences, University of California, Berkeley, Berkeley, CA, USA
- CIRM Center of Excellence, University of California, Berkeley, Berkeley, CA, USA
- Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA, USA
| | - R Tjian
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA.
- Li Ka Shing Center for Biomedical and Health Sciences, University of California, Berkeley, Berkeley, CA, USA
- CIRM Center of Excellence, University of California, Berkeley, Berkeley, CA, USA
- Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA, USA
| | - Y He
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA.
- Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL, USA
- Chemistry of Life Processes Institute, Northwestern University, Evanston, IL, USA
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Northwestern University, Chicago, IL, USA
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12
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Dean JM, He A, Tan M, Wang J, Lu D, Razani B, Lodhi IJ. MED19 Regulates Adipogenesis and Maintenance of White Adipose Tissue Mass by Mediating PPARγ-Dependent Gene Expression. Cell Rep 2020; 33:108228. [PMID: 33027649 PMCID: PMC7561447 DOI: 10.1016/j.celrep.2020.108228] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 08/11/2020] [Accepted: 09/14/2020] [Indexed: 12/13/2022] Open
Abstract
The Mediator complex relays regulatory signals from gene-specific transcription factors to the basal transcriptional machinery. However, the role of individual Mediator subunits in different tissues remains unclear. Here, we demonstrate that MED19 is essential for adipogenesis and maintenance of white adipose tissue (WAT) by mediating peroxisome proliferator-activated receptor gamma (PPARγ) transcriptional activity. MED19 knockdown blocks white adipogenesis, but not brown adipogenesis or C2C12 myoblast differentiation. Adipose-specific MED19 knockout (KO) in mice results in a striking loss of WAT, whitening of brown fat, hepatic steatosis, and insulin resistance. Inducible adipose-specific MED19 KO in adult animals also results in lipodystrophy, demonstrating its requirement for WAT maintenance. Global gene expression analysis reveals induction of genes involved in apoptosis and inflammation and impaired expression of adipose-specific genes, resulting from decreased PPARγ residency on adipocyte gene promoters and reduced association of PPARγ with RNA polymerase II. These results identify MED19 as a crucial facilitator of PPARγ-mediated gene expression in adipose tissue.
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Affiliation(s)
- John M Dean
- Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Anyuan He
- Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Min Tan
- Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jun Wang
- Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Dongliang Lu
- Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Babak Razani
- Cardiology Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA; Veterans Affairs St. Louis Healthcare System, John Cochran Division, St. Louis, MO 63106, USA
| | - Irfan J Lodhi
- Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
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13
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Smith LIF, Huang V, Olah M, Trinh L, Liu Y, Hazell G, Conway-Campbell B, Zhao Z, Martinez A, Lefrançois-Martinez AM, Lightman S, Spiga F, Aguilera G. Involvement of CREB-regulated transcription coactivators (CRTC) in transcriptional activation of steroidogenic acute regulatory protein (Star) by ACTH. Mol Cell Endocrinol 2020; 499:110612. [PMID: 31604124 PMCID: PMC6899503 DOI: 10.1016/j.mce.2019.110612] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 09/06/2019] [Accepted: 10/04/2019] [Indexed: 12/20/2022]
Abstract
Studies in vivo have suggested the involvement of CREB-regulated transcription coactivator (CRTC)2 on ACTH-induced transcription of the key steroidogenic protein, Steroidogenic Acute Regulatory (StAR). The present study uses two ACTH-responsive adrenocortical cell lines, to examine the role of CRTC on Star transcription. Here we show that ACTH-induced Star primary transcript, or heteronuclear RNA (hnRNA), parallels rapid increases in nuclear levels of the 3 isoforms of CRTC; CRTC1, CRTC2 and CRTC3. Furthermore, ACTH promotes recruitment of CRTC2 and CRTC3 by the Star promoter and siRNA knockdown of either CRTC3 or CRTC2 attenuates the increases in ACTH-induced Star hnRNA. Using pharmacological inhibitors of PKA, MAP kinase and calcineurin, we show that the effects of ACTH on Star transcription and CRTC nuclear translocation depend predominantly on the PKA pathway. The data provides evidence that CRTC2 and CRTC3, contribute to activation of Star transcription by ACTH, and that PKA/CRTC-dependent pathways are part of the multifactorial mechanisms regulating Star transcription.
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Affiliation(s)
- Lorna I F Smith
- Section on Endocrine Physiology, Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA; Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, University of Bristol, Bristol, UK.
| | - Victoria Huang
- Section on Endocrine Physiology, Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Mark Olah
- Section on Endocrine Physiology, Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Loc Trinh
- Section on Endocrine Physiology, Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Ying Liu
- Section on Endocrine Physiology, Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Georgina Hazell
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, University of Bristol, Bristol, UK
| | - Becky Conway-Campbell
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, University of Bristol, Bristol, UK
| | - Zidong Zhao
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, University of Bristol, Bristol, UK
| | - Antoine Martinez
- Génétique Reproduction & Développement, CNRS UMR 6293, Inserm U1103, Université Clermont Auvergne, 63001, Clermont-Ferrand, France
| | - Anne-Marie Lefrançois-Martinez
- Génétique Reproduction & Développement, CNRS UMR 6293, Inserm U1103, Université Clermont Auvergne, 63001, Clermont-Ferrand, France
| | - Stafford Lightman
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, University of Bristol, Bristol, UK
| | - Francesca Spiga
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, University of Bristol, Bristol, UK
| | - Greti Aguilera
- Section on Endocrine Physiology, Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
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14
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Jeon YG, Lee JH, Ji Y, Sohn JH, Lee D, Kim DW, Yoon SG, Shin KC, Park J, Seong JK, Cho JY, Choe SS, Kim JB. RNF20 Functions as a Transcriptional Coactivator for PPARγ by Promoting NCoR1 Degradation in Adipocytes. Diabetes 2020; 69:20-34. [PMID: 31604693 DOI: 10.2337/db19-0508] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 10/03/2019] [Indexed: 11/13/2022]
Abstract
Adipose tissue is the key organ coordinating whole-body energy homeostasis. Although it has been reported that ring finger protein 20 (RNF20) regulates lipid metabolism in the liver and kidney, the roles of RNF20 in adipose tissue have not been explored. Here, we demonstrate that RNF20 promotes adipogenesis by potentiating the transcriptional activity of peroxisome proliferator-activated receptor-γ (PPARγ). Under normal chow diet feeding, Rnf20 defective (Rnf20 +/- ) mice exhibited reduced fat mass with smaller adipocytes compared with wild-type littermates. In addition, high-fat diet-fed Rnf20 +/- mice alleviated systemic insulin resistance accompanied by a reduced expansion of fat tissue. Quantitative proteomic analyses revealed significantly decreased levels of PPARγ target proteins in adipose tissue of Rnf20 +/- mice. Mechanistically, RNF20 promoted proteasomal degradation of nuclear corepressor 1 (NCoR1), which led to stimulation of the transcriptional activity of PPARγ. Collectively, these data suggest that RNF20-NCoR1 is a novel axis in adipocyte biology through fine-tuning the transcriptional activity of PPARγ.
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Affiliation(s)
- Yong Geun Jeon
- National Creative Research Initiatives Center for Adipose Tissue Remodeling, Institute of Molecular Biology and Genetics, Department of Biological Sciences, Seoul National University, Seoul, Korea
| | - Jae Ho Lee
- National Creative Research Initiatives Center for Adipose Tissue Remodeling, Institute of Molecular Biology and Genetics, Department of Biological Sciences, Seoul National University, Seoul, Korea
| | - Yul Ji
- National Creative Research Initiatives Center for Adipose Tissue Remodeling, Institute of Molecular Biology and Genetics, Department of Biological Sciences, Seoul National University, Seoul, Korea
| | - Jee Hyung Sohn
- National Creative Research Initiatives Center for Adipose Tissue Remodeling, Institute of Molecular Biology and Genetics, Department of Biological Sciences, Seoul National University, Seoul, Korea
| | - Dabin Lee
- Department of Biochemistry, BK21 PLUS Program for Creative Veterinary Science Research and Research Institute for Veterinary Science, College of Veterinary Medicine, Seoul National University, Seoul, Korea
| | - Dong Wook Kim
- Department of Biochemistry, BK21 PLUS Program for Creative Veterinary Science Research and Research Institute for Veterinary Science, College of Veterinary Medicine, Seoul National University, Seoul, Korea
| | - Seul Gi Yoon
- Korea Mouse Phenotyping Center, Laboratory of Department of Anatomy and Cell Biology, BK21 PLUS Program for Creative Veterinary Science Research and Research Institute for Veterinary Science, College of Veterinary Medicine, Seoul National University, Seoul, Korea
| | - Kyung Cheul Shin
- National Creative Research Initiatives Center for Adipose Tissue Remodeling, Institute of Molecular Biology and Genetics, Department of Biological Sciences, Seoul National University, Seoul, Korea
| | - Jeu Park
- National Creative Research Initiatives Center for Adipose Tissue Remodeling, Institute of Molecular Biology and Genetics, Department of Biological Sciences, Seoul National University, Seoul, Korea
| | - Je Kyung Seong
- Korea Mouse Phenotyping Center, Laboratory of Department of Anatomy and Cell Biology, BK21 PLUS Program for Creative Veterinary Science Research and Research Institute for Veterinary Science, College of Veterinary Medicine, Seoul National University, Seoul, Korea
| | - Je-Yoel Cho
- Department of Biochemistry, BK21 PLUS Program for Creative Veterinary Science Research and Research Institute for Veterinary Science, College of Veterinary Medicine, Seoul National University, Seoul, Korea
| | - Sung Sik Choe
- National Creative Research Initiatives Center for Adipose Tissue Remodeling, Institute of Molecular Biology and Genetics, Department of Biological Sciences, Seoul National University, Seoul, Korea
| | - Jae Bum Kim
- National Creative Research Initiatives Center for Adipose Tissue Remodeling, Institute of Molecular Biology and Genetics, Department of Biological Sciences, Seoul National University, Seoul, Korea
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15
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Chen N, Schill RL, O'Donnell M, Xu K, Bagchi DP, MacDougald OA, Koenig RJ, Xu B. The transcription factor NKX1-2 promotes adipogenesis and may contribute to a balance between adipocyte and osteoblast differentiation. J Biol Chem 2019; 294:18408-18420. [PMID: 31615896 DOI: 10.1074/jbc.ra119.007967] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 10/04/2019] [Indexed: 11/06/2022] Open
Abstract
Although adipogenesis is mainly controlled by a small number of master transcription factors, including CCAAT/enhancer-binding protein family members and peroxisome proliferator-activated receptor γ (PPARγ), other transcription factors also are involved in this process. Thyroid cancer cells expressing a paired box 8 (PAX8)-PPARγ fusion oncogene trans-differentiate into adipocyte-like cells in the presence of the PPARγ ligand pioglitazone, but this trans-differentiation is inhibited by the transcription factor NK2 homeobox 1 (NKX2-1). Here, we tested whether NKX family members may play a role also in normal adipogenesis. Using quantitative RT-PCR (RT-qPCR), we examined the expression of all 14 NKX family members during 3T3-L1 adipocyte differentiation. We found that most NKX members, including NKX2-1, are expressed at very low levels throughout differentiation. However, mRNA and protein expression of a related family member, NKX1-2, was induced during adipocyte differentiation. NKX1-2 also was up-regulated in cultured murine ear mesenchymal stem cells (EMSCs) during adipogenesis. Importantly, shRNA-mediated NKX1-2 knockdown in 3T3-L1 preadipocytes or EMSCs almost completely blocked adipocyte differentiation. Furthermore, NKX1-2 overexpression promoted differentiation of the ST2 bone marrow-derived mesenchymal precursor cell line into adipocytes. Additional findings suggested that NKX1-2 promotes adipogenesis by inhibiting expression of the antiadipogenic protein COUP transcription factor II. Bone marrow mesenchymal precursor cells can differentiate into adipocytes or osteoblasts, and we found that NKX1-2 both promotes ST2 cell adipogenesis and inhibits their osteoblastogenic differentiation. These results support a role for NKX1-2 in promoting adipogenesis and possibly in regulating the balance between adipocyte and osteoblast differentiation of bone marrow mesenchymal precursor cells.
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Affiliation(s)
- Noah Chen
- Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Rebecca L Schill
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Michael O'Donnell
- Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Kevin Xu
- Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Devika P Bagchi
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Ormond A MacDougald
- Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan 48109; Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Ronald J Koenig
- Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Bin Xu
- Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan 48109.
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16
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Napoli C, Schiano C, Soricelli A. Increasing evidence of pathogenic role of the Mediator (MED) complex in the development of cardiovascular diseases. Biochimie 2019; 165:1-8. [PMID: 31255603 DOI: 10.1016/j.biochi.2019.06.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 06/24/2019] [Indexed: 12/20/2022]
Abstract
Cardiovascular diseases (CVDs) are the first cause of death in the World. Mediator (MED) is an evolutionarily conserved protein complex, which mediates distinct protein-protein interactions. Pathogenic events in MED subunit have been associated with human diseases. Novel increasing evidence showed that missense mutations in MED13L gene are associated with transposition of great arteries while MED12, MED13, MED15, and MED30, have been correlated with heart development. Moreover, MED23 and MED25 have been associated with heart malformations in humans. Relevantly, MED1, MED13, MED14, MED15, MED23, MED25, and CDK8, were found modify glucose and/or lipid metabolism. Indeed, MED1, MED15, MED25, and CDK8 interact in the PPAR- and SREBP-mediated signaling pathways. MED1, MED14 and MED23 are involved in adipocyte differentiation, whereas MED23 mediates smooth muscle cell differentiation. MED12, MED19, MED23, and MED30 regulate endothelial differentiation by alternative splicing mechanism. Thus, MEDs have a central role in early pathogenic events involved in CVDs representing novel targets for clinical prevention and therapeutic approaches.
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Affiliation(s)
- C Napoli
- University Department of Advanced Medical and Surgical Sciences, Clinical Department of Internal Medicine and Specialistic Units, University of Campania "L. Vanvitelli", 80138, Naples, Italy
| | | | - A Soricelli
- IRCCS SDN, 80143, Naples, Italy; Department of Motor Sciences and Healthiness, University of Naples Parthenope, 80134, Naples, Italy
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17
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Abstract
Understanding adipogenesis, the process of adipocyte development, may provide new ways to treat obesity and related metabolic diseases. Adipogenesis is controlled by coordinated actions of lineage-determining transcription factors and epigenomic regulators. Peroxisome proliferator-activated receptor gamma (PPARγ) and C/EBPα are master "adipogenic" transcription factors. In recent years, a growing number of studies have reported the identification of novel transcriptional and epigenomic regulators of adipogenesis. However, many of these novel regulators have not been validated in adipocyte development in vivo and their working mechanisms are often far from clear. In this minireview, we discuss recent advances in transcriptional and epigenomic regulation of adipogenesis, with a focus on factors and mechanisms shared by both white adipogenesis and brown adipogenesis. Studies on the transcriptional regulation of adipogenesis highlight the importance of investigating adipocyte differentiation in vivo rather than drawing conclusions based on knockdown experiments in cell culture. Advances in understanding of epigenomic regulation of adipogenesis have revealed critical roles of histone methylation/demethylation, histone acetylation/deacetylation, chromatin remodeling, DNA methylation, and microRNAs in adipocyte differentiation. We also discuss future research directions that may help identify novel factors and mechanisms regulating adipogenesis.
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18
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Amoasii L, Olson EN, Bassel-Duby R. Control of Muscle Metabolism by the Mediator Complex. Cold Spring Harb Perspect Med 2018; 8:cshperspect.a029843. [PMID: 28432117 DOI: 10.1101/cshperspect.a029843] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Exercise represents an energetic challenge to whole-body homeostasis. In skeletal muscle, exercise activates a variety of signaling pathways that culminate in the nucleus to regulate genes involved in metabolism and contractility; however, much remains to be learned about the transcriptional effectors of exercise. Mediator is a multiprotein complex that links signal-dependent transcription factors and other transcriptional regulators with the basal transcriptional machinery, thereby serving as a transcriptional "hub." In this article, we discuss recent studies highlighting the role of Mediator subunits in metabolic regulation and glucose metabolism, as well as exercise responsiveness. Elucidation of the roles of Mediator subunits in metabolic control has revealed new mechanisms and molecular targets for the modulation of metabolism and metabolic disorders.
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Affiliation(s)
- Leonela Amoasii
- Department of Molecular Biology, Hamon Center for Regenerative Science and Medicine, and Sen. Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, University of Texas Southwestern Medical Center, Dallas, Texas 7539-9148
| | - Eric N Olson
- Department of Molecular Biology, Hamon Center for Regenerative Science and Medicine, and Sen. Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, University of Texas Southwestern Medical Center, Dallas, Texas 7539-9148
| | - Rhonda Bassel-Duby
- Department of Molecular Biology, Hamon Center for Regenerative Science and Medicine, and Sen. Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, University of Texas Southwestern Medical Center, Dallas, Texas 7539-9148
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19
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Ranjan A, Ansari SA. Therapeutic potential of Mediator complex subunits in metabolic diseases. Biochimie 2017; 144:41-49. [PMID: 29061530 DOI: 10.1016/j.biochi.2017.10.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 10/16/2017] [Indexed: 01/16/2023]
Abstract
The multisubunit Mediator is an evolutionary conserved transcriptional coregulatory complex in eukaryotes. It is needed for the transcriptional regulation of gene expression in general as well as in a gene specific manner. Mediator complex subunits interact with different transcription factors as well as components of RNA Pol II transcription initiation complex and in doing so act as a bridge between gene specific transcription factors and general Pol II transcription machinery. Specific interaction of various Mediator subunits with nuclear receptors (NRs) and other transcription factors involved in metabolism has been reported in different studies. Evidences indicate that ligand-activated NRs recruit Mediator complex for RNA Pol II-dependent gene transcription. These NRs have been explored as therapeutic targets in different metabolic diseases; however, they show side-effects as targets due to their overlapping involvement in different signaling pathways. Here we discuss the interaction of various Mediator subunits with transcription factors involved in metabolism and whether specific interaction of these transcription factors with Mediator subunits could be potentially utilized as therapeutic strategy in a variety of metabolic diseases.
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Affiliation(s)
- Amol Ranjan
- Stowers Institute for Medical Research, 1000 E, 50th Street, Kansas City, MO, 64110, USA
| | - Suraiya A Ansari
- Department of Biochemistry, College of Medicine and Health Sciences, UAE University, AlAin, Abu Dhabi, United Arab Emirates.
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20
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Crosstalk between the Androgen Receptor and PPAR Gamma Signaling Pathways in the Prostate. PPAR Res 2017; 2017:9456020. [PMID: 29181019 PMCID: PMC5664321 DOI: 10.1155/2017/9456020] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 08/29/2017] [Accepted: 09/14/2017] [Indexed: 01/07/2023] Open
Abstract
Nuclear receptors are a superfamily of ligand-activated transcription factors that play critical roles in the regulation of normal biological processes and several disease states. Of the nuclear receptors expressed within the prostate, the androgen receptor (AR) promotes the differentiation of prostatic epithelial cells and stimulates production of enzymes needed for liquefaction of semen. Multiple forms of AR also promote the growth of both early and late stage prostate cancers. As a result, drugs that target the AR signaling pathway are routinely used to treat patients with advanced forms of prostate cancer. Data also suggest that a second member of the nuclear receptor superfamily, the peroxisome proliferator activated receptor gamma (PPARγ), is a tumor suppressor that regulates growth of normal prostate and prostate cancers. Recent studies indicate there is a bidirectional interaction between AR and PPARγ, with each receptor influencing the expression and/or activity of the other within prostatic tissues. In this review, we examine how AR and PPARγ each regulate the growth and development of normal prostatic epithelial cells and prostate cancers. We also discuss interactions between the AR and PPARγ signaling pathways and how those interactions may influence prostate biology.
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21
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Eychenne T, Werner M, Soutourina J. Toward understanding of the mechanisms of Mediator function in vivo: Focus on the preinitiation complex assembly. Transcription 2017; 8:328-342. [PMID: 28841352 DOI: 10.1080/21541264.2017.1329000] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Mediator is a multisubunit complex conserved in eukaryotes that plays an essential coregulator role in RNA polymerase (Pol) II transcription. Despite intensive studies of the Mediator complex, the molecular mechanisms of its function in vivo remain to be fully defined. In this review, we will discuss the different aspects of Mediator function starting with its interactions with specific transcription factors, its recruitment to chromatin and how, as a coregulator, it contributes to the assembly of transcription machinery components within the preinitiation complex (PIC) in vivo and beyond the PIC formation.
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Affiliation(s)
- Thomas Eychenne
- a Institute for Integrative Biology of the Cell (I2BC), Institute of Life Sciences Frédéric Joliot, CEA, CNRS , Univ. Paris Sud, University Paris Saclay , Gif-sur-Yvette , France.,b Institut Pasteur, (Epi)genomics of Animal Development Unit , Development and Stem Cell Biology Department, CNRS UMR3778 , Paris , France
| | - Michel Werner
- a Institute for Integrative Biology of the Cell (I2BC), Institute of Life Sciences Frédéric Joliot, CEA, CNRS , Univ. Paris Sud, University Paris Saclay , Gif-sur-Yvette , France
| | - Julie Soutourina
- a Institute for Integrative Biology of the Cell (I2BC), Institute of Life Sciences Frédéric Joliot, CEA, CNRS , Univ. Paris Sud, University Paris Saclay , Gif-sur-Yvette , France
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22
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Song Z, Xiaoli AM, Zhang Q, Zhang Y, Yang EST, Wang S, Chang R, Zhang ZD, Yang G, Strich R, Pessin JE, Yang F. Cyclin C regulates adipogenesis by stimulating transcriptional activity of CCAAT/enhancer-binding protein α. J Biol Chem 2017; 292:8918-8932. [PMID: 28351837 DOI: 10.1074/jbc.m117.776229] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 03/27/2017] [Indexed: 11/06/2022] Open
Abstract
Brown adipose tissue is important for maintaining energy homeostasis and adaptive thermogenesis in rodents and humans. As disorders arising from dysregulated energy metabolism, such as obesity and metabolic diseases, have increased, so has interest in the molecular mechanisms of adipocyte biology. Using a functional screen, we identified cyclin C (CycC), a conserved subunit of the Mediator complex, as a novel regulator for brown adipocyte formation. siRNA-mediated CycC knockdown (KD) in brown preadipocytes impaired the early transcriptional program of differentiation, and genetic KO of CycC completely blocked the differentiation process. RNA sequencing analyses of CycC-KD revealed a critical role of CycC in activating genes co-regulated by peroxisome proliferator activated receptor γ (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα). Overexpression of PPARγ2 or addition of the PPARγ ligand rosiglitazone rescued the defects in CycC-KO brown preadipocytes and efficiently activated the PPARγ-responsive promoters in both WT and CycC-KO cells, suggesting that CycC is not essential for PPARγ transcriptional activity. In contrast, CycC-KO significantly reduced C/EBPα-dependent gene expression. Unlike for PPARγ, overexpression of C/EBPα could not induce C/EBPα target gene expression in CycC-KO cells or rescue the CycC-KO defects in brown adipogenesis, suggesting that CycC is essential for C/EBPα-mediated gene activation. CycC physically interacted with C/EBPα, and this interaction was required for C/EBPα transactivation domain activity. Consistent with the role of C/EBPα in white adipogenesis, CycC-KD also inhibited differentiation of 3T3-L1 cells into white adipocytes. Together, these data indicate that CycC activates adipogenesis in part by stimulating the transcriptional activity of C/EBPα.
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Affiliation(s)
- Ziyi Song
- From the Laboratory of Animal Fat Deposition and Muscle Development, Department of Animal Sciences, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, China.,the Department of Medicine, Division of Endocrinology and Diabetes Research Center, and
| | - Alus M Xiaoli
- the Department of Medicine, Division of Endocrinology and Diabetes Research Center, and.,Departments of Developmental and Molecular Biology
| | | | - Yi Zhang
- the Department of Medicine, Division of Endocrinology and Diabetes Research Center, and.,Departments of Developmental and Molecular Biology
| | - Ellen S T Yang
- the Department of Medicine, Division of Endocrinology and Diabetes Research Center, and.,Departments of Developmental and Molecular Biology
| | - Sven Wang
- the Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, and
| | - Rui Chang
- the Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, and
| | | | - Gongshe Yang
- From the Laboratory of Animal Fat Deposition and Muscle Development, Department of Animal Sciences, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, China,
| | - Randy Strich
- the Department of Molecular Biology, Rowan University School of Osteopathic Medicine, Stratford, New Jersey 08055
| | - Jeffrey E Pessin
- the Department of Medicine, Division of Endocrinology and Diabetes Research Center, and.,Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Fajun Yang
- the Department of Medicine, Division of Endocrinology and Diabetes Research Center, and .,Departments of Developmental and Molecular Biology
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23
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Drosophila TRF2 and TAF9 regulate lipid droplet size and phospholipid fatty acid composition. PLoS Genet 2017; 13:e1006664. [PMID: 28273089 PMCID: PMC5362240 DOI: 10.1371/journal.pgen.1006664] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 03/22/2017] [Accepted: 02/28/2017] [Indexed: 11/19/2022] Open
Abstract
The general transcription factor TBP (TATA-box binding protein) and its associated factors (TAFs) together form the TFIID complex, which directs transcription initiation. Through RNAi and mutant analysis, we identified a specific TBP family protein, TRF2, and a set of TAFs that regulate lipid droplet (LD) size in the Drosophila larval fat body. Among the three Drosophila TBP genes, trf2, tbp and trf1, only loss of function of trf2 results in increased LD size. Moreover, TRF2 and TAF9 regulate fatty acid composition of several classes of phospholipids. Through RNA profiling, we found that TRF2 and TAF9 affects the transcription of a common set of genes, including peroxisomal fatty acid β-oxidation-related genes that affect phospholipid fatty acid composition. We also found that knockdown of several TRF2 and TAF9 target genes results in large LDs, a phenotype which is similar to that of trf2 mutants. Together, these findings provide new insights into the specific role of the general transcription machinery in lipid homeostasis. Lipid droplets (LD) are main lipid storage structures in most cells. The size of LDs varies greatly in different cell types or different metabolic states to accommodate cellular functions and metabolism demands. How cells regulate the lipid storage and LD dynamics is not fully understood. Here, we identified that general transcription factors, including a specific TBP (TATA-box binding protein) family protein TRF2 (TBP-related factor 2) and several TAFs (TBP-associated factors), regulate LD size in the fruitfly larval fat body. Moreover, quantitated lipid analysis reveals that TRF2 and TAF9 affect the fatty acid composition of several classes of phospholipids. We showed that TRF2 and TAF9 regulate transcription of several target genes, including peroxisomal fatty acid β-oxidation-related genes which likely mediate the effect of TRF2 and TAF9 on phospholipid fatty acid composition. We also found that overexpression of some target genes restores the LD phenotype in trf2 mutants. Our findings therefore reveal specific roles of general transcription factors in lipid homeostasis.
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24
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Regulation of metabolism by the Mediator complex. BIOPHYSICS REPORTS 2016; 2:69-77. [PMID: 28018965 PMCID: PMC5138257 DOI: 10.1007/s41048-016-0031-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 02/15/2016] [Indexed: 01/11/2023] Open
Abstract
The Mediator complex was originally discovered in yeast, but it is conserved in all eukaryotes. Its best-known function is to regulate RNA polymerase II-dependent gene transcription. Although the mechanisms by which the Mediator complex regulates transcription are often complicated by the context-dependent regulation, this transcription cofactor complex plays a pivotal role in numerous biological pathways. Biochemical, molecular, and physiological studies using cancer cell lines or model organisms have established the current paradigm of the Mediator functions. However, the physiological roles of the mammalian Mediator complex remain poorly defined, but have attracted a great interest in recent years. In this short review, we will summarize some of the reported functions of selective Mediator subunits in the regulation of metabolism. These intriguing findings suggest that the Mediator complex may be an important player in nutrient sensing and energy balance in mammals.
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25
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Khalyfa A, Kheirandish-Gozal L, Bhattacharjee R, Khalyfa AA, Gozal D. Circulating microRNAs as Potential Biomarkers of Endothelial Dysfunction in Obese Children. Chest 2016; 149:786-800. [PMID: 26270249 DOI: 10.1378/chest.15-0799] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Cardiovascular disease (CVD) is a complex disease with multifactorial etiology. The presence of endothelial dysfunction constitutes an early risk factor for CVD in children. Circulating microRNAs (miRNAs) are small noncoding RNAs that regulate gene expression and represent a novel class of biomarkers and therapeutic targets; therefore, we examined whether the presence of endothelial dysfunction is associated with differential expression of plasma miRNAs in otherwise healthy children. METHODS A total of 70 children (aged 5-10 years) were recruited and classified into two groups (normal endothelial function [NEF] and endothelial dysfunction). Time to peak postocclusive reperfusion (Tmax) was considered as the indicator of either normal endothelial function (NEF; Tmax < 45 s) or endothelial dysfunction (Tmax ≥ 45 s). Lipid profiles, high-sensitivity C-reactive protein, fasting glucose, and insulin were assayed using enzyme-linked immunosorbent assay. miRNAs isolated from plasma were assayed with a custom human CVD array, followed by quantitative polymerase chain reaction verification of candidates. In addition, bioinformatics approaches including combinatorial target prediction algorithms and gene ontology were applied. RESULTS Three miRNAs that have been previously linked to cardiomyopathy, hsa-miR-125a-5p, hsa-miR-342-3p, and hsa-miR-365b-3p, were identified as potential biomarkers of children with endothelial dysfunction. The miRNA predicted gene targets revealed 31 common targets among all three putative candidate biomarker miRNAs and encompass three biologic pathways, including transforming growth factor-β signaling, cytokine-cytokine receptor interactions, and activin receptor-like kinase in cardiac myocytes. CONCLUSIONS Plasma miRNAs may be useful as potential screening tools for the presence of endothelial dysfunction in children and may reveal endothelial dysfunction-relevant target genes.
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Affiliation(s)
- Abdelnaby Khalyfa
- Department of Pediatrics, Pritzker School of Medicine, Biological Sciences Division, The University of Chicago, Chicago, IL
| | - Leila Kheirandish-Gozal
- Department of Pediatrics, Pritzker School of Medicine, Biological Sciences Division, The University of Chicago, Chicago, IL
| | - Rakesh Bhattacharjee
- Department of Pediatrics, Pritzker School of Medicine, Biological Sciences Division, The University of Chicago, Chicago, IL
| | - Ahamed A Khalyfa
- Department of Pediatrics, Pritzker School of Medicine, Biological Sciences Division, The University of Chicago, Chicago, IL
| | - David Gozal
- Department of Pediatrics, Pritzker School of Medicine, Biological Sciences Division, The University of Chicago, Chicago, IL.
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26
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Youssef J, Badr M. Peroxisome Proliferator-Activated Receptors Features, Functions, and Future. NUCLEAR RECEPTOR RESEARCH 2015. [DOI: 10.11131/2015/101188] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
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27
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Lou X, Burrows JTA, Scott IC. Med14 cooperates with brg1 in the differentiation of skeletogenic neural crest. BMC DEVELOPMENTAL BIOLOGY 2015; 15:41. [PMID: 26553192 PMCID: PMC4640375 DOI: 10.1186/s12861-015-0090-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 10/25/2015] [Indexed: 11/17/2022]
Abstract
Background An intricate gene regulatory network drives neural crest migration and differentiation. How epigenetic regulators contribute to this process is just starting to be understood. Results We found that mutation of med14 or brg1 in zebrafish embryos resulted in a cluster of neural crest cell-related defects. In med14 or brg1 mutants, neural crest cells that form the jaw skeleton were specified normally and migrated to target sites. However, defects in their subsequent terminal differentiation were evident. Transplantation experiments demonstrated that med14 and brg1 are required directly in neural crest cells. Analysis of med14; brg1 double mutant embryos suggested the existence of a strong genetic interaction between members of the Mediator and BAF complexes. Conclusions These results suggest a critical role for Mediator and BAF complex function in neural crest development, and may also clarify the nature of defects in some craniofacial abnormalities.
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Affiliation(s)
- Xin Lou
- Model Animal Research Center, Nanjing University, 12 Xuefu Road, Nanjing, 210061, Jiangsu, China. .,Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, 686 Bay Street, Toronto, Ontario, M5G 0A4, Canada. .,Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, M5S 1A8, Ontario, Canada. .,Heart & Stroke/Richard Lewar Centre of Excellence, University of Toronto, 101 College Street, Toronto, M5G 1L7, Ontario, Canada.
| | - Jeffrey T A Burrows
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, 686 Bay Street, Toronto, Ontario, M5G 0A4, Canada. .,Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, M5S 1A8, Ontario, Canada.
| | - Ian C Scott
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, 686 Bay Street, Toronto, Ontario, M5G 0A4, Canada. .,Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, M5S 1A8, Ontario, Canada. .,Heart & Stroke/Richard Lewar Centre of Excellence, University of Toronto, 101 College Street, Toronto, M5G 1L7, Ontario, Canada.
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28
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Bionaz M, Monaco E, Wheeler MB. Transcription Adaptation during In Vitro Adipogenesis and Osteogenesis of Porcine Mesenchymal Stem Cells: Dynamics of Pathways, Biological Processes, Up-Stream Regulators, and Gene Networks. PLoS One 2015; 10:e0137644. [PMID: 26398344 PMCID: PMC4580618 DOI: 10.1371/journal.pone.0137644] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 07/27/2015] [Indexed: 12/20/2022] Open
Abstract
The importance of mesenchymal stem cells (MSC) for bone regeneration is growing. Among MSC the bone marrow-derived stem cells (BMSC) are considered the gold standard in tissue engineering and regenerative medicine; however, the adipose-derived stem cells (ASC) have very similar properties and some advantages to be considered a good alternative to BMSC. The molecular mechanisms driving adipogenesis are relatively well-known but mechanisms driving osteogenesis are poorly known, particularly in pig. In the present study we have used transcriptome analysis to unravel pathways and biological functions driving in vitro adipogenesis and osteogenesis in BMSC and ASC. The analysis was performed using the novel Dynamic Impact Approach and functional enrichment analysis. In addition, a k-mean cluster analysis in association with enrichment analysis, networks reconstruction, and transcription factors overlapping analysis were performed in order to uncover the coordination of biological functions underlining differentiations. Analysis indicated a larger and more coordinated transcriptomic adaptation during adipogenesis compared to osteogenesis, with a larger induction of metabolism, particularly lipid synthesis (mostly triglycerides), and a larger use of amino acids for synthesis of feed-forward adipogenic compounds, larger cell signaling, lower cell-to-cell interactions, particularly for the cytoskeleton organization and cell junctions, and lower cell proliferation. The coordination of adipogenesis was mostly driven by Peroxisome Proliferator-activated Receptors together with other known adipogenic transcription factors. Only a few pathways and functions were more induced during osteogenesis compared to adipogenesis and some were more inhibited during osteogenesis, such as cholesterol and protein synthesis. Up-stream transcription factor analysis indicated activation of several lipid-related transcription regulators (e.g., PPARs and CEBPα) during adipogenesis but osteogenesis was driven by inhibition of several up-stream regulators, such as MYC. Between MSCs the data indicated an ‘adipocyte memory’ in ASC with also an apparent lower immunogenicity compared to BMSC during differentiations. Overall the analysis allowed proposing a dynamic model for the adipogenic and osteogenic differentiation in porcine ASC and BMSC.
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Affiliation(s)
- Massimo Bionaz
- Laboratory of Stem Cell Biology and Engineering in the Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
- Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Elisa Monaco
- Laboratory of Stem Cell Biology and Engineering in the Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
- Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Matthew B. Wheeler
- Laboratory of Stem Cell Biology and Engineering in the Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
- Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
- * E-mail:
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29
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Watanabe M, Takahashi H, Saeki Y, Ozaki T, Itoh S, Suzuki M, Mizushima W, Tanaka K, Hatakeyama S. The E3 ubiquitin ligase TRIM23 regulates adipocyte differentiation via stabilization of the adipogenic activator PPARγ. eLife 2015; 4:e05615. [PMID: 25905670 PMCID: PMC4426667 DOI: 10.7554/elife.05615] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 04/21/2015] [Indexed: 12/19/2022] Open
Abstract
Adipocyte differentiation is a strictly controlled process regulated by a series of transcriptional activators. Adipogenic signals activate early adipogenic activators and facilitate the transient formation of early enhanceosomes at target genes. These enhancer regions are subsequently inherited by late enhanceosomes. PPARγ is one of the late adipogenic activators and is known as a master regulator of adipogenesis. However, the factors that regulate PPARγ expression remain to be elucidated. Here, we show that a novel ubiquitin E3 ligase, tripartite motif protein 23 (TRIM23), stabilizes PPARγ protein and mediates atypical polyubiquitin conjugation. TRIM23 knockdown caused a marked decrease in PPARγ protein abundance during preadipocyte differentiation, resulting in a severe defect in late adipogenic differentiation, whereas it did not affect the formation of early enhanceosomes. Our results suggest that TRIM23 plays a critical role in the switching from early to late adipogenic enhanceosomes by stabilizing PPARγ protein possibly via atypical polyubiquitin conjugation. DOI:http://dx.doi.org/10.7554/eLife.05615.001 The world is facing a global epidemic of obesity, which also increases the risk for diabetes and heart disease. Obesity is caused when excess fat is stored in fat cells, and overweight individuals have larger fat cells compared to healthy weight people. Therefore understanding how fat cells are created in the body can provide new ways to combat obesity. Fat cells, also known as adipocytes, arise from precursor cells via a process called adipogenesis. This requires the activity of proteins called transcription factors that bind to DNA and switch on the expression of genes. PPARγ is an important transcription factor that drives the expression of the genes that are needed to convert a precursor cell to a mature adipocyte. For adipogenesis to proceed, cells have to maintain the appropriate levels of PPARγ. If the amount of PPARγ bound to DNA is too low, then it is unable to activate gene expression. However, the mechanisms by which cells maintain the correct levels of PPARγ activity remain poorly understood. Watanabe et al. analyzed this process in mouse cells and identified a protein called TRIM23 that is produced in precursor cells. Cells in which the levels of TRIM23 were artificially lowered failed to mature into fat cells; this suggests that this protein is necessary for adipogenesis. Furthermore, in the absence of TRIM23, the amount of PPARγ that occupied regions of DNA was also markedly reduced. A direct consequence of this was a decline in the expression of several genes that are required for the later steps in the adipogenesis process. Watanabe et al. next analyzed the mechanism through which TRIM23 had an effect on the levels of PPARγ. It is known from previous work that TRIM23 belongs to a family of enzymes that attach a small molecular tag called ubiquitin onto other proteins. This ubiquitin tag typically marks these proteins for rapid destruction by a large molecular machine called the proteasome. Watanabe et al. found that TRIM23 also modified PPARγ with ubiquitin, but that it did so in an unusual manner that instead prevented the proteasome from recognizing PPARγ and destroying it. As such, TRIM23 stabilizes the levels of PPARγ in cells. By providing new insights into how adipogenesis is regulated, these findings suggest that TRIM23 may be a potential therapeutic target in the treatment of diabetes and disorders related to obesity. DOI:http://dx.doi.org/10.7554/eLife.05615.002
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Affiliation(s)
- Masashi Watanabe
- Department of Biochemistry, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Hidehisa Takahashi
- Department of Biochemistry, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Yasushi Saeki
- Laboratory of Protein Metabolism, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Takashi Ozaki
- Department of Biochemistry, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Shihori Itoh
- Department of Biochemistry, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Masanobu Suzuki
- Department of Biochemistry, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Wataru Mizushima
- Department of Biochemistry, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Keiji Tanaka
- Laboratory of Protein Metabolism, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Shigetsugu Hatakeyama
- Department of Biochemistry, Hokkaido University Graduate School of Medicine, Sapporo, Japan
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30
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Simões J, Amado FM, Vitorino R, Helguero LA. A meta-analysis to evaluate the cellular processes regulated by the interactome of endogenous and over-expressed estrogen receptor alpha. Oncoscience 2015; 2:487-496. [PMID: 26097882 PMCID: PMC4468335 DOI: 10.18632/oncoscience.138] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Accepted: 03/04/2015] [Indexed: 01/08/2023] Open
Abstract
The nature of the proteins complexes that regulate ERα subcellular localization and activity is still an open question in breast cancer biology. Identification of such complexes will help understand development of endocrine resistance in ER+ breast cancer. Mass spectrometry (MS) has allowed comprehensive analysis of the ERα interactome. We have compared six published works analyzing the ERα interactome of MCF-7 and HeLa cells in order to identify a shared or different pathway-related fingerprint. Overall, 806 ERα interacting proteins were identified. The cellular processes were differentially represented according to the ERα purification methodology, indicating that the methodologies used are complementary. While in MCF-7 cells, the interactome of endogenous and over-expressed ERα essentially represents the same biological processes and cellular components, the proteins identified were not over-lapping; thus, suggesting that the biological response may differ as the regulatory/participating proteins in these complexes are different. Interestingly, biological processes uniquely associated to ERα over-expressed in HeLa cell line included L-serine biosynthetic process, cellular amino acid biosynthetic process and cell redox homeostasis. In summary, all the approaches analyzed in this meta-analysis are valid and complementary; in particular, for those cases where the processes occur at low frequency with normal ERα levels, and can be identified when the receptor is over-expressed. However special effort should be put into validating these findings in cells expressing physiological ERα levels.
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Affiliation(s)
- Joana Simões
- Mass Spectrometry Centre, QOPNA Research Unit, Department of Chemistry, Universidade de Aveiro, Campus Universitário de Santiago, Aveiro, Portugal
| | - Francisco M Amado
- Mass Spectrometry Centre, QOPNA Research Unit, Department of Chemistry, Universidade de Aveiro, Campus Universitário de Santiago, Aveiro, Portugal.,School of Healh Sciences, Universidade de Aveiro, Portugal
| | - Rui Vitorino
- Mass Spectrometry Centre, QOPNA Research Unit, Department of Chemistry, Universidade de Aveiro, Campus Universitário de Santiago, Aveiro, Portugal.,Institute for Research in Biomedicine - iBiMED, Health Sciences Program, Universidade de Aveiro, Portugal
| | - Luisa A Helguero
- Mass Spectrometry Centre, QOPNA Research Unit, Department of Chemistry, Universidade de Aveiro, Campus Universitário de Santiago, Aveiro, Portugal.,Institute for Research in Biomedicine - iBiMED, Health Sciences Program, Universidade de Aveiro, Portugal
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Abstract
FBW7 (F-box and WD repeat domain-containing 7) or Fbxw7 is a tumor suppressor, which promotes the ubiquitination and subsequent degradation of numerous oncoproteins including Mcl-1, Cyclin E, Notch, c- Jun, and c-Myc. In turn, FBW7 is regulated by multiple upstream factors including p53, C/EBP-δ, EBP2, Pin1, Hes-5 and Numb4 as well as by microRNAs such as miR-223, miR-27a, miR-25, and miR-129-5p. Given that the Fbw7 tumor suppressor is frequently inactivated or deleted in various human cancers, targeting FBW7 regulators is a promising anti-cancer therapeutic strategy.
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32
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Liver Med23 ablation improves glucose and lipid metabolism through modulating FOXO1 activity. Cell Res 2014; 24:1250-65. [PMID: 25223702 PMCID: PMC4185346 DOI: 10.1038/cr.2014.120] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 07/03/2014] [Accepted: 07/27/2014] [Indexed: 12/23/2022] Open
Abstract
Mediator complex is a molecular hub integrating signaling, transcription factors, and RNA polymerase II (RNAPII) machinery. Mediator MED23 is involved in adipogenesis and smooth muscle cell differentiation, suggesting its role in energy homeostasis. Here, through the generation and analysis of a liver-specific Med23-knockout mouse, we found that liver Med23 deletion improved glucose and lipid metabolism, as well as insulin responsiveness, and prevented diet-induced obesity. Remarkably, acute hepatic Med23 knockdown in db/db mice significantly improved the lipid profile and glucose tolerance. Mechanistically, MED23 participates in gluconeogenesis and cholesterol synthesis through modulating the transcriptional activity of FOXO1, a key metabolic transcription factor. Indeed, hepatic Med23 deletion impaired the Mediator and RNAPII recruitment and attenuated the expression of FOXO1 target genes. Moreover, this functional interaction between FOXO1 and MED23 is evolutionarily conserved, as the in vivo activities of dFOXO in larval fat body and in adult wing can be partially blocked by Med23 knockdown in Drosophila. Collectively, our data revealed Mediator MED23 as a novel regulator for energy homeostasis, suggesting potential therapeutic strategies against metabolic diseases.
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33
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Lefterova MI, Haakonsson AK, Lazar MA, Mandrup S. PPARγ and the global map of adipogenesis and beyond. Trends Endocrinol Metab 2014; 25:293-302. [PMID: 24793638 PMCID: PMC4104504 DOI: 10.1016/j.tem.2014.04.001] [Citation(s) in RCA: 418] [Impact Index Per Article: 41.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 04/08/2014] [Accepted: 04/09/2014] [Indexed: 10/25/2022]
Abstract
Peroxisome proliferator-activated receptor γ (PPARγ) is a member of the nuclear receptor (NR) superfamily of ligand-dependent transcription factors (TFs) and function as a master regulator of adipocyte differentiation and metabolism. We review recent breakthroughs in the understanding of PPARγ gene regulation and function in the chromatin context. It is now clear that multiple TFs team up to induce PPARγ during adipogenesis, and that other TFs cooperate with PPARγ to ensure adipocyte-specific genomic binding and function. We discuss how this differs in other PPARγ-expressing cells such as macrophages and how these genome-wide mechanisms are preserved across species despite modest conservation of specific binding sites. These emerging considerations inform our understanding of PPARγ function as well as of adipocyte development and physiology.
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Affiliation(s)
- Martina I Lefterova
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA; Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, and Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Anders K Haakonsson
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense, Denmark
| | - Mitchell A Lazar
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, and Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Susanne Mandrup
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense, Denmark.
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34
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Yin JW, Wang G. The Mediator complex: a master coordinator of transcription and cell lineage development. Development 2014; 141:977-87. [PMID: 24550107 DOI: 10.1242/dev.098392] [Citation(s) in RCA: 146] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Mediator is a multiprotein complex that is required for gene transcription by RNA polymerase II. Multiple subunits of the complex show specificity in relaying information from signals and transcription factors to the RNA polymerase II machinery, thus enabling control of the expression of specific genes. Recent studies have also provided novel mechanistic insights into the roles of Mediator in epigenetic regulation, transcriptional elongation, termination, mRNA processing, noncoding RNA activation and super enhancer formation. Based on these specific roles in gene regulation, Mediator has emerged as a master coordinator of development and cell lineage determination. Here, we describe the most recent advances in understanding the mechanisms of Mediator function, with an emphasis on its role during development and disease.
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Affiliation(s)
- Jing-wen Yin
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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35
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Schiano C, Casamassimi A, Vietri MT, Rienzo M, Napoli C. The roles of mediator complex in cardiovascular diseases. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1839:444-51. [PMID: 24751643 DOI: 10.1016/j.bbagrm.2014.04.012] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 03/19/2014] [Accepted: 04/11/2014] [Indexed: 02/08/2023]
Abstract
Despite recent treatment advances, an increase in cardiovascular diseases (CVD) mortality is expected for the next years. Mediator (MED) complex plays key roles in eukaryotic gene transcription. Currently, while numerous studies have correlated MED alterations with several diseases, like cancer or neurological disorders, fewer studies have investigated MED role in CVD initiation and progression. The first finding of MED involvement in these pathologies was the correlation of missense mutations in MED13L gene with transposition of the great arteries. Nowadays, also MED13 and MED15 have been associated with human congenital heart diseases and others could be added, like MED12 that is involved in early mouse development and heart formation. Interestingly, a missense mutation in MED30 gene causes a progressive cardiomyopathy in homozygous mice suggesting a potential role for this subunit also in human CVDs. Moreover, several subunits like MED1, MED13, MED14, MED15, MED23, MED25 and CDK8 exert important roles in glucose and lipid metabolism. Although these evidences derive from in vitro and animal model studies, they indicate that their deregulation may have a significant role in human CVD-related metabolic disorders. Finally, alternative transcripts of MED12, MED19 and MED30 are differently expressed in circulating endothelial progenitor cells thus suggesting they can play a role in the field of regenerative medicine. Overall, further functional studies exploring MED role in human CVD are warranted. The results could allow identifying novel biomarkers to use in combination with imaging techniques for early diagnosis; otherwise, they could be useful to develop targets for novel therapeutic approaches.
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Affiliation(s)
- Concetta Schiano
- Institute of Diagnostic and Nuclear Development (SDN), IRCCS, Via E. Gianturco 113, 80143 Naples, Italy
| | - Amelia Casamassimi
- Department of Biochemistry, Biophysics and General Pathology, Second University of Naples, Via L. De Crecchio 7, 80138 Naples, Italy.
| | - Maria Teresa Vietri
- Department of Biochemistry, Biophysics and General Pathology, Second University of Naples, Via L. De Crecchio 7, 80138 Naples, Italy
| | - Monica Rienzo
- Department of Biochemistry, Biophysics and General Pathology, Second University of Naples, Via L. De Crecchio 7, 80138 Naples, Italy
| | - Claudio Napoli
- Institute of Diagnostic and Nuclear Development (SDN), IRCCS, Via E. Gianturco 113, 80143 Naples, Italy; Department of Biochemistry, Biophysics and General Pathology, Second University of Naples, Via L. De Crecchio 7, 80138 Naples, Italy; U.O.C. Immunohematology, Transfusion Medicine and Transplant Immunology [SIMT], Regional Reference Laboratory of Transplant Immunology [LIT], Azienda Universitaria Policlinico (AOU), 1st School of Medicine, Second University of Naples, Piazza Miraglia 2, 80138 Naples, Italy
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Gao Y, Kalkhoven E. TIPping the balance in adipogenesis: USP7-mediated stabilization of Tip60. Adipocyte 2014; 3:160-5. [PMID: 24719792 DOI: 10.4161/adip.28307] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2013] [Revised: 02/20/2014] [Accepted: 02/20/2014] [Indexed: 01/19/2023] Open
Abstract
Adipogenesis is regulated by a complex interplay between transcription factors, in concert with-among others-transcriptional cofactors, signaling cascades and miRNAs. Several studies have implicated the transcriptional cofactor and acetyltransferase Tip60 in PPARγ signaling and adipocyte differentiation. Since Tip60 protein levels, but not mRNA levels, are upregulated during adipogenesis, and since Tip60 can be degraded by the proteasome, we hypothesized that Tip60 protein may be stabilized through deubiquitination during adipogenesis. Indeed, Tip60 is protected from proteasomal degeradation by the deubiquitinase USP7, which is particularly important for mitotic clonal expansion (MCE), an early step in adipogenesis. Besides this novel role in early differentiation, earlier studies indicated that Tip60 is also important during the later stages of differentiation, indicating a dual role for this protein in adipogenesis. Our recent study sheds new light on the role of Tip60 in cellular differentiation and provide new insights into the importance of a regulatory process that has not been studied intensively in adipogenesis: protein (de)ubiquitination.
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Peroxisome proliferator-activated receptor γ and C/EBPα synergistically activate key metabolic adipocyte genes by assisted loading. Mol Cell Biol 2013; 34:939-54. [PMID: 24379442 DOI: 10.1128/mcb.01344-13] [Citation(s) in RCA: 173] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer binding protein α (C/EBPα) are key activators of adipogenesis. They mutually induce the expression of each other and have been reported to cooperate in activation of a few adipocyte genes. Recently, genome-wide profiling revealed a high degree of overlap between PPARγ and C/EBPα binding in adipocytes, suggesting that cooperativeness could be mediated through common binding sites. To directly investigate the interplay between PPARγ and C/EBPα at shared binding sites, we established a fibroblastic model system in which PPARγ and C/EBPα can be independently expressed. Using RNA sequencing, we demonstrate that coexpression of PPARγ and C/EBPα leads to synergistic activation of many key metabolic adipocyte genes. This is associated with extensive C/EBPα-mediated reprogramming of PPARγ binding and vice versa in the vicinity of these genes, as determined by chromatin immunoprecipitation combined with deep sequencing. Our results indicate that this is at least partly mediated by assisted loading involving chromatin remodeling directed by the leading factor. In conclusion, we report a novel mechanism by which the key adipogenic transcription factors, PPARγ and C/EBPα, cooperate in activation of the adipocyte gene program.
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Abstract
The Mediator complex is a multi-subunit assembly that appears to be required for regulating expression of most RNA polymerase II (pol II) transcripts, which include protein-coding and most non-coding RNA genes. Mediator and pol II function within the pre-initiation complex (PIC), which consists of Mediator, pol II, TFIIA, TFIIB, TFIID, TFIIE, TFIIF and TFIIH and is approximately 4.0 MDa in size. Mediator serves as a central scaffold within the PIC and helps regulate pol II activity in ways that remain poorly understood. Mediator is also generally targeted by sequence-specific, DNA-binding transcription factors (TFs) that work to control gene expression programs in response to developmental or environmental cues. At a basic level, Mediator functions by relaying signals from TFs directly to the pol II enzyme, thereby facilitating TF-dependent regulation of gene expression. Thus, Mediator is essential for converting biological inputs (communicated by TFs) to physiological responses (via changes in gene expression). In this review, we summarize an expansive body of research on the Mediator complex, with an emphasis on yeast and mammalian complexes. We focus on the basics that underlie Mediator function, such as its structure and subunit composition, and describe its broad regulatory influence on gene expression, ranging from chromatin architecture to transcription initiation and elongation, to mRNA processing. We also describe factors that influence Mediator structure and activity, including TFs, non-coding RNAs and the CDK8 module.
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Affiliation(s)
- Zachary C Poss
- Department of Chemistry and Biochemistry, University of Colorado , Boulder, CO , USA
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Galbraith MD, Saxton J, Li L, Shelton SJ, Zhang H, Espinosa JM, Shaw PE. ERK phosphorylation of MED14 in promoter complexes during mitogen-induced gene activation by Elk-1. Nucleic Acids Res 2013; 41:10241-53. [PMID: 24049075 PMCID: PMC3905876 DOI: 10.1093/nar/gkt837] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The ETS domain transcription factor Elk-1 stimulates expression of immediate early genes (IEGs) in response to mitogens. These events require phosphorylation of Elk-1 by extracellular signal-regulated kinase (ERK) and phosphorylation-dependent interaction of Elk-1 with co-activators, including histone acetyltransferases and the Mediator complex. Elk-1 also recruits ERK to the promoters of its target genes, suggesting that ERK phosphorylates additional substrates in transcription complexes at mitogen-responsive promoters. Here we report that MED14, a core subunit of the Mediator, is a bona fide ERK substrate and identify serine 986 (S986) within a serine-proline rich region of MED14 as the major ERK phosphorylation site. Mitogens induced phosphorylation of MED14 on S986 at IEG promoters; RNAi knockdown of MED14 reduced CDK8 and RNA polymerase II (RNAPII) recruitment, RNAPII C-terminal domain phosphorylation and impaired activation of IEG transcription. A single alanine substitution at S986 reduced activation of an E26 (ETS)-responsive reporter by oncogenic Ras and mitogen-induced, Elk-1-dependent transcription, whereas activities of other transcriptional activators were unaffected. We also demonstrate that Elk-1 can associate with MED14 independently of MED23, which may facilitate phosphorylation of MED14 by ERK to impart a positive and selective impact on mitogen-responsive gene expression.
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Affiliation(s)
- Matthew D Galbraith
- School of Biomedical Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, NG7 2UH, UK, Department of Molecular, Cellular and Developmental Biology, Howard Hughes Medical Institute, University of Colorado at Boulder, Boulder, CO 80309, USA, Department of Neurology, Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, CA 90089, USA and Department of Pharmacology, Ningxia Medical University, Yinchuan 750004, China
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Ansari SA, Morse RH. Mechanisms of Mediator complex action in transcriptional activation. Cell Mol Life Sci 2013; 70:2743-56. [PMID: 23361037 PMCID: PMC11113466 DOI: 10.1007/s00018-013-1265-9] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Revised: 01/07/2013] [Accepted: 01/09/2013] [Indexed: 12/14/2022]
Abstract
Mediator is a large multisubunit complex that plays a central role in the regulation of RNA Pol II transcribed genes. Conserved in overall structure and function among eukaryotes, Mediator comprises 25-30 protein subunits that reside in four distinct modules, termed head, middle, tail, and CDK8/kinase. Different subunits of Mediator contact other transcriptional regulators including activators, co-activators, general transcription factors, subunits of RNA Pol II, and specifically modified histones, leading to the regulated expression of target genes. This review is focused on the interactions of specific Mediator subunits with diverse transcription regulators and how those interactions contribute to Mediator function in transcriptional activation.
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Affiliation(s)
- Suraiya A. Ansari
- Laboratory of Molecular Genetics, Wadsworth Center, New York State Department of Health, Albany, NY 12201–0509 USA
| | - Randall H. Morse
- Laboratory of Molecular Genetics, Wadsworth Center, New York State Department of Health, Albany, NY 12201–0509 USA
- Department of Biomedical Science, University at Albany School of Public Health, Albany, NY USA
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Katano-Toki A, Satoh T, Tomaru T, Yoshino S, Ishizuka T, Ishii S, Ozawa A, Shibusawa N, Tsuchiya T, Saito T, Shimizu H, Hashimoto K, Okada S, Yamada M, Mori M. THRAP3 interacts with HELZ2 and plays a novel role in adipocyte differentiation. Mol Endocrinol 2013; 27:769-80. [PMID: 23525231 DOI: 10.1210/me.2012-1332] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Using yeast two-hybrid screen, we previously isolated HELZ2 (helicase with zinc finger 2, transcriptional coactivator) that functions as a coregulator of peroxisome proliferator-activated receptorγ (PPARγ). To further delineate its molecular function, we here identified thyroid hormone receptor-associated protein3 (THRAP3), a putative component of the Mediator complex, as a protein stably associating with HELZ2 using immunoprecipitation coupled with mass spectrometry analyses. In immunoprecipitation assays, Thrap3 could associate with endogenous Helz2 as well as Pparg in differentiated 3T3-L1 cells. HELZ2 interacts with the serine/arginine-rich domain and Bcl2 associated transcription factor1-homologous region in THRAP3, whereas THRAP3 directly binds 2 helicase motifs in HELZ2. HELZ2 and THRAP3 synergistically augment transcriptional activation mediated by PPARγ, whereas knockdown of endogenous THRAP3 abolished the enhancement by HELZ2 in reporter assays. Thrap3, similar to Helz2, is evenly expressed in the process of adipogenic differentiation in 3T3-L1 cells. Knockdown of Thrap3 in 3T3-L1 preadipocytes using short-interfering RNA did not influence the expression of Krox20, Klf5, Cebpb, or Cebpd during early stages of adipocyte differentiation, but significantly attenuated the expression of Pparg, Cebpa, and Fabp4/aP2 and accumulation of lipid droplets. Pharmacologic activation of Pparg by troglitazone could not fully restore the differentiation of Thrap3-knockdown adipocytes. In chromatin immunoprecipitation assays, endogenous Helz2 and Thrap3 could be co-recruited, in a ligand-dependent manner, to the PPARγ-response elements in Fabp4/aP2 and Adipoq gene enhancers in differentiated 3T3-L1 cells. These findings collectively suggest that Thrap3 could play indispensable roles in terminal differentiation of adipocytes by enhancing PPARγ-mediated gene activation cooperatively with Helz2.
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Affiliation(s)
- Akiko Katano-Toki
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi, Japan
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Zhou H, Kaplan T, Li Y, Grubisic I, Zhang Z, Wang PJ, Eisen MB, Tjian R. Dual functions of TAF7L in adipocyte differentiation. eLife 2013; 2:e00170. [PMID: 23326641 PMCID: PMC3539393 DOI: 10.7554/elife.00170] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2012] [Accepted: 11/09/2012] [Indexed: 12/22/2022] Open
Abstract
The diverse transcriptional mechanisms governing cellular differentiation and development of mammalian tissue remains poorly understood. Here we report that TAF7L, a paralogue of TFIID subunit TAF7, is enriched in adipocytes and white fat tissue (WAT) in mouse. Depletion of TAF7L reduced adipocyte-specific gene expression, compromised adipocyte differentiation, and WAT development as well. Ectopic expression of TAF7L in myoblasts reprograms these muscle precursors into adipocytes upon induction. Genome-wide mRNA-seq expression profiling and ChIP-seq binding studies confirmed that TAF7L is required for activating adipocyte-specific genes via a dual mechanism wherein it interacts with PPARγ at enhancers and TBP/Pol II at core promoters. In vitro binding studies confirmed that TAF7L forms complexes with both TBP and PPARγ. These findings suggest that TAF7L plays an integral role in adipocyte gene expression by targeting enhancers as a cofactor for PPARγ and promoters as a component of the core transcriptional machinery. DOI:http://dx.doi.org/10.7554/eLife.00170.001 The development of a single fertilized egg into a highly complex animal is determined by its genome, with a process called differential gene regulation exerting exquisite control over gene expression to ensure that various specialized cells are generated and that many types of tissue are produced. However, the mechanisms responsible for controlling gene expression and, therefore mammalian development, are poorly understood. Researchers have developed a number of in vitro cell culture models to elucidate the details of differential gene regulation, and this approach has been used to characterize adipocytes—cells that store energy in the form of fat—for close to two decades. The formation of adipocytes, a process known as adipogenesis, has been extensively studied, but there remain major gaps in our knowledge: for example, the identities of many of the transcriptional regulators that are responsible for the differentiation of mesenchymal stem cells into adipocytes remain a mystery. This task is complicated by the fact that some of these regulators are involved in the differentiation of multiple cell lines, and that some of them also have multiple roles in the generation of a single cell type. In addition to being of fundamental interest, improving our knowledge of the properties and behavior of adipocytes is essential for tackling the increasing prevalence of obesity in the developed world. Zhou et al. now report that TAF7L—a gene that was previously thought to be involved only in the production of sperm cells—has two roles in the differentiation of stem cells to form adipocytes. Using a combination of cellular, biochemical, genetic and genomic techniques, they show that TAF7L interacts with PPARγ, an important adipocyte transcriptional regulator at enhancer sites on the genome to increase the transcription of genes that are involved in adipogenesis. They also show that TAF7L interacts with a general transcription factor called TBP (short for TATA-binding protein) at promoter sequences, again to increase the expression of genes involved in adipogenesis. Moreover, they show that the expression of TAF7L in myoblasts—precursor cells that usually become muscle cells—can induce the formation of fat cells rather than muscle cells. Furthermore, mice lacking TAF7L are lean compared to their normal littermates. A clearer understanding of the underlying causes of fat cell formation could lead to the development of new approaches for the treatment of obesity and associated diseases. DOI:http://dx.doi.org/10.7554/eLife.00170.002
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Affiliation(s)
- Haiying Zhou
- Department of Molecular and Cell Biology , Howard Hughes Medical Institute, University of California, Berkeley , Berkeley , United States ; Li Ka Shing Center For Biomedical and Health Sciences, CIRM Center of Excellence, University of California, Berkeley , Berkeley , United States
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Eeckhoute J, Oger F, Staels B, Lefebvre P. Coordinated Regulation of PPARγ Expression and Activity through Control of Chromatin Structure in Adipogenesis and Obesity. PPAR Res 2012; 2012:164140. [PMID: 22991504 PMCID: PMC3444001 DOI: 10.1155/2012/164140] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Accepted: 07/10/2012] [Indexed: 12/14/2022] Open
Abstract
The nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ) is required for differentiation and function of mature adipocytes. Its expression is induced during adipogenesis where it plays a key role in establishing the transcriptome of terminally differentiated white fat cells. Here, we review findings indicating that PPARγ expression and activity are intricately regulated through control of chromatin structure. Hierarchical and combinatorial activation of transcription factors, noncoding RNAs, and chromatin remodelers allows for temporally controlled expression of PPARγ and its target genes through sequential chromatin remodelling. In obesity, these regulatory pathways may be altered and lead to modified PPARγ activity.
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Affiliation(s)
- Jérôme Eeckhoute
- Université Lille Nord de France, 59000 Lille, France
- Inserm, U1011, 59000 Lille, France
- UDSL, 59000 Lille, France
- Institut Pasteur de Lille, 59019 Lille, France
| | - Frédérik Oger
- Université Lille Nord de France, 59000 Lille, France
- Inserm, U1011, 59000 Lille, France
- UDSL, 59000 Lille, France
- Institut Pasteur de Lille, 59019 Lille, France
| | - Bart Staels
- Université Lille Nord de France, 59000 Lille, France
- Inserm, U1011, 59000 Lille, France
- UDSL, 59000 Lille, France
- Institut Pasteur de Lille, 59019 Lille, France
| | - Philippe Lefebvre
- Université Lille Nord de France, 59000 Lille, France
- Inserm, U1011, 59000 Lille, France
- UDSL, 59000 Lille, France
- Institut Pasteur de Lille, 59019 Lille, France
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The Mediator complex in thyroid hormone receptor action. Biochim Biophys Acta Gen Subj 2012; 1830:3867-75. [PMID: 22402254 DOI: 10.1016/j.bbagen.2012.02.012] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Revised: 02/16/2012] [Accepted: 02/21/2012] [Indexed: 10/28/2022]
Abstract
BACKGROUND Mediator is an evolutionarily conserved multisubunit complex that plays an essential regulatory role in eukaryotic transcription of protein-encoding genes. The human complex was first isolated as a transcriptional coactivator bound to the thyroid hormone receptor (TR) and has since been shown to play a key coregulatory role for a broad range of nuclear hormone receptors (NRs) as well as other signal-activated transcription factors. SCOPE OF REVIEW We provide a general overview of Mediator structure and function, summarize the mechanisms by which Mediator is targeted to NRs, and outline recent evidence revealing Mediator as a regulatory axis for other distinct coregulatory factors, chromatin modifying enzymes and cellular signal transduction pathways. MAJOR CONCLUSIONS Besides serving as a functional interface with the RNA polymerase II basal transcription machinery, Mediator plays a more versatile role in regulating transcription including the ability to: a) facilitate gene-specific chromatin looping events; b) coordinate chromatin modification events with preinitiation complex assembly; and c) regulate critical steps that occur during transcriptional elongation. The variably associated MED1 subunit continues to emerge as a pivotal player in Mediator function, not only as the primary interaction site for NRs, but also as a crucial interaction hub for other coregulatory factors, and as an important regulatory target for signal-activated kinases. GENERAL SIGNIFICANCE Mediator plays an integral coregulatory role at NR target genes by functionally interacting with the basal transcription apparatus and by coordinating the action of chromatin modifying enzymes and transcription elongation factors. This article is part of a Special Issue entitled Thyroid hormone signalling.
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Poulsen LLC, Siersbæk M, Mandrup S. PPARs: fatty acid sensors controlling metabolism. Semin Cell Dev Biol 2012; 23:631-9. [PMID: 22273692 DOI: 10.1016/j.semcdb.2012.01.003] [Citation(s) in RCA: 336] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Accepted: 01/09/2012] [Indexed: 12/13/2022]
Abstract
The peroxisome proliferator activated receptors (PPARs) are nuclear receptors that play key roles in the regulation of lipid metabolism, inflammation, cellular growth, and differentiation. The receptors bind and are activated by a broad range of fatty acids and fatty acid derivatives and they thereby serve as major transcriptional sensors of fatty acids. Here we review the function, regulation, and mechanism of the different PPAR subtypes with special emphasis on their role in the regulation of lipid metabolism.
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Affiliation(s)
- Lars la Cour Poulsen
- University of Southern Denmark, Department of Biochemistry and Molecular Biology, Campusvej 55, DK-5230, Odense M, Denmark.
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Distinct role of Mediator tail module in regulation of SAGA-dependent, TATA-containing genes in yeast. EMBO J 2011; 31:44-57. [PMID: 21971086 DOI: 10.1038/emboj.2011.362] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Accepted: 09/07/2011] [Indexed: 11/08/2022] Open
Abstract
The evolutionarily conserved Mediator complex is required for transcription of nearly all RNA Pol II-dependent promoters, with the tail module serving to recruit Mediator to active promoters in current models. However, transcriptional dependence on tail module subunits varies in a gene-specific manner, and the generality of the tail module requirement for transcriptional activation has not been explored. Here, we show that tail module subunits function redundantly to recruit Mediator to promoters in yeast, and transcriptome analysis shows stronger effects on genome-wide expression in a double-tail subunit deletion mutant than in single-subunit deletion mutants. Unexpectedly, TATA-containing and SAGA-dependent genes were much more affected by impairment of tail module function than were TFIID-dependent genes. Consistent with this finding, Mediator and preinitiation complex association with SAGA-dependent promoters is substantially reduced in gal11/med15Δ med3Δ yeast, whereas association of TBP, Pol II, and other Mediator modules with TFIID-dependent genes is largely independent of the tail module. Thus, we have identified a connection between the Mediator tail module and the division of promoter dependence between TFIID and SAGA.
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Abstract
How is specificity transmitted over long distances at the molecular level? REs (regulatory elements) are often far from transcription start sites. In the present review we discuss possible mechanisms to explain how information from specific REs is conveyed to the basal transcription machinery through TFs (transcription factors) and the Mediator complex. We hypothesize that this occurs through allosteric pathways: binding of a TF to a RE results in changes in the AD (activation domain) of the TF, which binds to Mediator and alters the distribution of the Mediator conformations, thereby affecting transcription initiation/activation. We argue that Mediator is formed by highly disordered proteins with large densely packed interfaces that make efficient long-range signal propagation possible. We suggest two possible general mechanisms for Mediator action: one in which Mediator influences PIC (pre-initiation complex) assembly and transcription initiation, and another in which Mediator exerts its effect on the already assembled but stalled transcription complex. We summarize (i) relevant information from the literature about Mediator composition, organization and structure; (ii) Mediator interaction partners and their effect on Mediator conformation, function and correlation to the RNA Pol II (polymerase II) CTD (C-terminal domain) phosphorylation; and (iii) propose that different allosteric signal propagation pathways in Mediator relate to PIC assembly and polymerase activation of the stalled transcription complex. The emerging picture provides for the first time a mechanistic view of allosteric signalling from the RE sequence to transcription activation, and an insight into how gene specificity and signal transmission can take place in transcription initiation.
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Affiliation(s)
- Chung-Jung Tsai
- Basic Science Program, SAIC-Frederick, Center for Cancer Research Nanobiology Program NCI-Frederick, Frederick, MD 21702, U.S.A
| | - Ruth Nussinov
- Basic Science Program, SAIC-Frederick, Center for Cancer Research Nanobiology Program NCI-Frederick, Frederick, MD 21702, U.S.A
- Sackler Institute of Molecular Medicine, Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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48
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Unraveling framework of the ancestral Mediator complex in human diseases. Biochimie 2011; 94:579-87. [PMID: 21983542 DOI: 10.1016/j.biochi.2011.09.016] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Accepted: 09/15/2011] [Indexed: 01/13/2023]
Abstract
Mediator (MED) is a fundamental component of the RNA polymerase II-mediated transcription machinery. This multiprotein complex plays a pivotal role in the regulation of eukaryotic mRNA synthesis. The yeast Mediator complex consists of 26 different subunits. Recent studies indicate additional pathogenic roles for Mediator, for example during transcription elongation and non-coding RNA production. Mediator subunits have been emerging also to have pathophysiological roles suggesting MED-dependent therapeutic targets involving in several diseases, such as cancer, cardiovascular disease (CVD), metabolic and neurological disorders.
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49
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Chen W, Roeder RG. Mediator-dependent nuclear receptor function. Semin Cell Dev Biol 2011; 22:749-58. [PMID: 21854863 DOI: 10.1016/j.semcdb.2011.07.026] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 07/20/2011] [Indexed: 12/24/2022]
Abstract
As gene-specific transcription factors, nuclear receptors are broadly involved in many important biological processes. Their function on target genes requires the stepwise assembly of different coactivator complexes that facilitate chromatin remodeling and subsequent preinitiation complex (PIC) formation and function. Mediator has proved to be a crucial, and general, nuclear receptor-interacting coactivator, with demonstrated functions in transcription steps ranging from chromatin remodeling to subsequent PIC formation and function. Here we discuss our current understanding of (i) pathways involved in Mediator recruitment and function through nuclear receptor target gene enhancers and promoters, (ii) conditional requirements for the strong nuclear receptor-Mediator interactions mediated by NR AF2 domains and the MED1 LXXLL motifs, (iii) Mediator functions, through different nuclear receptor-interacting subunits, in different metabolic pathways, (iv) emerging functions of Mediator as a corepressor in addition to its major role as a coactivator and (v) mechanisms by which Mediator acts to transmit signals from enhancer-bound nuclear receptors to the general transcription machinery at core promoters to effect PIC formation and function. As a nuclear receptor coregulator with increasingly diverse functions, Mediator may thus modulate nuclear receptor signaling through several different mechanisms.
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Affiliation(s)
- Wei Chen
- Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, 1230 York Ave., New York, NY 10065, USA.
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50
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Interactions between subunits of the Mediator complex with gene-specific transcription factors. Semin Cell Dev Biol 2011; 22:759-68. [PMID: 21839847 DOI: 10.1016/j.semcdb.2011.07.022] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Revised: 07/26/2011] [Accepted: 07/28/2011] [Indexed: 11/24/2022]
Abstract
The Mediator complex forms the bridge between gene-specific transcription factors and the RNA polymerase II (RNAP II) machinery. Mediator is a large polypetide complex consisting of about thirty polypeptides that are mostly conserved from yeast to human. Mediator coordinates RNAP II recruitment, phosphorylation of the C-terminal domain of RNAP II, enhancer-loop formation and post-initiation events. The focus of the review is to summarize the current knowledge of transcription factor/Mediator interactions in higher eukaryotes and illuminate the physiological and gene-selective roles of Mediator.
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