scholarly journals MED14 Tethers Mediator to the N-Terminal Domain of Peroxisome Proliferator-Activated Receptor γ and Is Required for Full Transcriptional Activity and Adipogenesis

2010 ◽  
Vol 30 (9) ◽  
pp. 2155-2169 ◽  
Author(s):  
Lars Grøntved ◽  
Maria S. Madsen ◽  
Michael Boergesen ◽  
Robert G. Roeder ◽  
Susanne Mandrup
Keyword(s):  
Rna Polymerase Ii ◽  
Transcriptional Activity ◽  
Target Gene ◽  
Target Genes ◽  
Gene Activation ◽  
Proximal Promoter ◽  
Peroxisome Proliferator ◽  
Independent Manner ◽  
Peroxisome Proliferator Activated Receptor ◽  
Terminal Domain

ABSTRACT The Mediator subunit MED1/TRAP220/DRIP205/PBP interacts directly with many nuclear receptors and was long thought to be responsible for tethering Mediator to peroxisome proliferator-activated receptor (PPAR)-responsive promoters. However, it was demonstrated recently that PPARγ can recruit Mediator by MED1-independent mechanisms. Here, we show that target gene activation by ectopically expressed PPARγ and PPARα is independent of MED1. Consistent with this finding, recruitment of PPARγ, MED6, MED8, TATA box-binding protein (TBP), and RNA polymerase II (RNAPII) to the enhancer and proximal promoter of the PPARγ target gene Fabp4 is also independent of MED1. Using a small interfering RNA (siRNA)-based approach, we identify MED14 as a novel critical Mediator component for PPARγ-dependent transactivation, and we demonstrate that MED14 interacts directly with the N terminus of PPARγ in a ligand-independent manner. Interestingly, MED14 knockdown does not affect the recruitment of PPARγ, MED6, and MED8 to the Fabp4 enhancer but does reduce their occupancy of the Fabp4 proximal promoter. In agreement with the necessity of MED14 for PPARγ transcriptional activity, we show that knockdown of MED14 impairs adipogenesis of 3T3-L1 cells. Thus, MED14 constitutes a novel anchoring point between Mediator and the N-terminal domain of PPARγ that is necessary for functional PPARγ-mediated recruitment of Mediator and transactivation of PPARγ subtype-specific target genes.

scholarly journals Alternative Mechanisms by Which Mediator Subunit MED1/TRAP220 Regulates Peroxisome Proliferator-Activated Receptor γ-Stimulated Adipogenesis and Target Gene Expression

2007 ◽  
Vol 28 (3) ◽  
pp. 1081-1091 ◽  
Author(s):  
Kai Ge ◽  
Young-Wook Cho ◽  
Hong Guo ◽  
Teresa B. Hong ◽  
Mohamed Guermah ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rna Polymerase Ii ◽  
Nuclear Receptor ◽  
Transcriptional Activity ◽  
Target Gene ◽  
Molecular Mechanisms ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Cultured Fibroblasts ◽  
Target Gene Expression

ABSTRACT Mediator is a general coactivator complex connecting transcription activators and RNA polymerase II. Recent work has shown that the nuclear receptor-interacting MED1/TRAP220 subunit of Mediator is required for peroxisome proliferator-activated receptor γ (PPARγ)-stimulated adipogenesis of mouse embryonic fibroblasts (MEFs). However, the molecular mechanisms remain undefined. Here, we show an intracellular PPARγ-Mediator interaction that requires the two LXXLL nuclear receptor recognition motifs on MED1/TRAP220 and, furthermore, we show that the intact LXXLL motifs are essential for optimal PPARγ function in a reconstituted cell-free transcription system. Surprisingly, a conserved N-terminal region of MED1/TRAP220 that lacks the LXXLL motifs but gets incorporated into Mediator fully supports PPARγ-stimulated adipogenesis. Moreover, in undifferentiated MEFs, MED1/TRAP220 is dispensable both for PPARγ-mediated target gene activation and for recruitment of Mediator to a PPAR response element on the aP2 target gene promoter. However, PPARγ shows significantly reduced transcriptional activity in cells deficient for a subunit (MED24/TRAP100) important for the integrity of the Mediator complex, indicating a general Mediator requirement for PPARγ function. These results indicate that there is a conditional requirement for MED1/TRAP220 and that a direct interaction between PPARγ and Mediator through MED1/TRAP220 is not essential either for PPARγ-stimulated adipogenesis or for PPARγ target gene expression in cultured fibroblasts. As Mediator is apparently essential for PPARγ transcriptional activity, our data indicate the presence of alternative mechanisms for Mediator recruitment, possibly through intermediate cofactors or other cofactors that are functionally redundant with MED1/TRAP220.

scholarly journals Peroxisome Proliferator-Activated Receptor γ Target Gene Encoding a Novel Angiopoietin-Related Protein Associated with Adipose Differentiation

2000 ◽  
Vol 20 (14) ◽  
pp. 5343-5349 ◽  
Author(s):  
J. Cliff Yoon ◽  
Troy W. Chickering ◽  
Evan D. Rosen ◽  
Barry Dussault ◽  
Yubin Qin ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Time Course ◽  
Target Gene ◽  
Target Genes ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Isolation And Characterization ◽  
Adipose Differentiation ◽  
Novel Target

ABSTRACT The nuclear receptor peroxisome proliferator-activated receptor γ regulates adipose differentiation and systemic insulin signaling via ligand-dependent transcriptional activation of target genes. However, the identities of the biologically relevant target genes are largely unknown. Here we describe the isolation and characterization of a novel target gene induced by PPARγ ligands, termed PGAR (for PPARγ angiopoietin related), which encodes a novel member of the angiopoietin family of secreted proteins. The transcriptional induction of PGAR follows a rapid time course typical of immediate-early genes and occurs in the absence of protein synthesis. The expression of PGAR is predominantly localized to adipose tissues and placenta and is consistently elevated in genetic models of obesity. Hormone-dependent adipocyte differentiation coincides with a dramatic early induction of the PGAR transcript. Alterations in nutrition and leptin administration are found to modulate the PGAR expression in vivo. Taken together, these data suggest a possible role for PGAR in the regulation of systemic lipid metabolism or glucose homeostasis.

SUMO modification selectively regulates transcriptional activity of peroxisome-proliferator-activated receptor γ in C2C12 myotubes

2010 ◽  
Vol 433 (1) ◽  
pp. 155-161 ◽  
Author(s):  
Sung Soo Chung ◽  
Byung Yong Ahn ◽  
Min Kim ◽  
Jun Ho Kho ◽  
Hye Seung Jung ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Transcriptional Activity ◽  
Target Genes ◽  
C2c12 Cells ◽  
C2c12 Myotubes ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Mouse Muscle ◽  
Fatty Acid Binding ◽  
Specific Protease

PPAR (peroxisome-proliferator-activated receptor) γ, a nuclear receptor, can be conjugated with SUMO (small ubiquitin-like modifier), which results in the negative regulation of its transcriptional activity. In the present study, we tested whether de-SUMOylation of PPARγ affects the expression of PPARγ target genes in mouse muscle cells and investigated the mechanism by which de-SUMOylation increases PPARγ transcriptional activity. We found that the SUMO-specific protease SENP2 [SUMO1/sentrin/SMT3 (suppressor of mif two 3 homologue 1)-specific peptidase 2] effectively de-SUMOylates PPARγ–SUMO conjugates. Overexpression of SENP2 in C2C12 cells increased the expression of some PPARγ target genes, such as FABP3 (fatty-acid-binding protein 3) and CD36 (fatty acid translocase), both in the absence and presence of rosiglitazone. In contrast, overexpression of SENP2 did not affect the expression of another PPARγ target gene ADRP (adipose differentiation-related protein). De-SUMOylation of PPARγ increased ChIP (chromatin immunoprecipitation) of both a recombinant PPRE (PPAR-response element) and endogenous PPREs of the target genes CD36 and FABP3, but ChIP of the PPRE in the ADRP promoter was not affected by SENP2 overexpression. In conclusion, these results indicate that SENP2 de-SUMOylates PPARγ in myotubes, and de-SUMOylation of PPARγ selectively increases the expression of some PPARγ target genes.

scholarly journals Dysregulation of the Peroxisome Proliferator-Activated Receptor Target Genes by XPD Mutations

2005 ◽  
Vol 25 (14) ◽  
pp. 6065-6076 ◽  
Author(s):  
Emmanuel Compe ◽  
Pascal Drané ◽  
Camille Laurent ◽  
Karin Diderich ◽  
Cathy Braun ◽  
...  
Keyword(s):  
Target Genes ◽  
Genetic Disorders ◽  
Peroxisome Proliferator ◽  
Wild Type ◽  
Independent Manner ◽  
Peroxisome Proliferator Activated Receptor ◽  
Pol Ii ◽  
Knowing That ◽  
Peroxisome Proliferator Activated Receptors ◽  
Ppar Ligands

ABSTRACT Mutations in the XPD subunit of TFIIH give rise to human genetic disorders initially defined as DNA repair syndromes. Nevertheless, xeroderma pigmentosum (XP) group D (XP-D) patients develop clinical features such as hypoplasia of the adipose tissue, implying a putative transcriptional defect. Knowing that peroxisome proliferator-activated receptors (PPARs) are implicated in lipid metabolism, we investigated the expression of PPAR target genes in the adipose tissues and the livers of XPD-deficient mice and found that (i) some genes are abnormally overexpressed in a ligand-independent manner which parallels an increase in the recruitment of RNA polymerase (pol) II but not PPARs on their promoter and (ii) upon treatment with PPAR ligands, other genes are much less induced compared to the wild type, which is due to a lower recruitment of both PPARs and RNA pol II. The defect in transactivation by PPARs is likely attributable to their weaker phosphorylation by the cdk7 kinase of TFIIH. Having identified the phosphorylated residues in PPAR isotypes, we demonstrate how their transactivation defect in XPD-deficient cells can be circumvented by overexpression of either a wild-type XPD or a constitutively phosphorylated PPAR S/E. This work emphasizes that underphosphorylation of PPARs affects their transactivation and consequently the expression of PPAR target genes, thus contributing in part to the XP-D phenotype.

The serine/threonine phosphatase PPM1B (PP2Cβ) selectively modulates PPARγ activity

2013 ◽  
Vol 451 (1) ◽  
pp. 45-53 ◽  
Author(s):  
Ismayil Tasdelen ◽  
Olivier van Beekum ◽  
Olena Gorbenko ◽  
Veerle Fleskens ◽  
Niels J. F. van den Broek ◽  
...  
Keyword(s):  
Protein Phosphatase ◽  
Transcriptional Activity ◽  
Target Genes ◽  
Cellular Proteins ◽  
Peroxisome Proliferator ◽  
Serine Residue ◽  
Intact Cells ◽  
Peroxisome Proliferator Activated Receptor ◽  
Interacting Protein

Reversible phosphorylation is a widespread molecular mechanism to regulate the function of cellular proteins, including transcription factors. Phosphorylation of the nuclear receptor PPARγ (peroxisome-proliferator-activated receptor γ) at two conserved serine residue (Ser112 and Ser273) results in an altered transcriptional activity of this transcription factor. So far, only a very limited number of cellular enzymatic activities has been described which can dephosphorylate nuclear receptors. In the present study we used immunoprecipitation assays coupled to tandem MS analysis to identify novel PPARγ-regulating proteins. We identified the serine/threonine phosphatase PPM1B [PP (protein phosphatase), Mg2+/Mn2+ dependent, 1B; also known as PP2Cβ] as a novel PPARγ-interacting protein. Endogenous PPM1B protein is localized in the nucleus of mature 3T3-L1 adipocytes where it can bind to PPARγ. Furthermore we show that PPM1B can directly dephosphorylate PPARγ, both in intact cells and in vitro. In addition PPM1B increases PPARγ-mediated transcription via dephosphorylation of Ser112. Finally, we show that knockdown of PPM1B in 3T3-L1 adipocytes blunts the expression of some PPARγ target genes while leaving others unaltered. These findings qualify the phosphatase PPM1B as a novel selective modulator of PPARγ activity.

scholarly journals The Adipogenic Acetyltransferase Tip60 Targets Activation Function 1 of Peroxisome Proliferator-Activated Receptor γ

Endocrinology ◽  
2007 ◽  
Vol 149 (4) ◽  
pp. 1840-1849 ◽  
Author(s):  
Olivier van Beekum ◽  
Arjan B. Brenkman ◽  
Lars Grøntved ◽  
Nicole Hamers ◽  
Niels J. F. van den Broek ◽  
...  
Keyword(s):  
Transcriptional Activity ◽  
Target Genes ◽  
Activation Function ◽  
Specific Gene ◽  
Chimeric Proteins ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Interacting Protein ◽  
And Function ◽  
Interfering Rna

The transcription factor peroxisome proliferator-activated receptor γ (PPARγ) plays a key role in the regulation of lipid and glucose metabolism in adipocytes, by regulating their differentiation, maintenance, and function. The transcriptional activity of PPARγ is dictated by the set of proteins with which this nuclear receptor interacts under specific conditions. Here we identify the HIV-1 Tat-interacting protein 60 (Tip60) as a novel positive regulator of PPARγ transcriptional activity. Using tandem mass spectrometry, we found that PPARγ and the acetyltransferase Tip60 interact in cells, and through use of chimeric proteins, we established that coactivation by Tip60 critically depends on the N-terminal activation function 1 of PPARγ, a domain involved in isotype-specific gene expression and adipogenesis. Chromatin immunoprecipitation experiments showed that the endogenous Tip60 protein is recruited to PPARγ target genes in mature 3T3-L1 adipocytes but not in preadipocytes, indicating that Tip60 requires PPARγ for its recruitment to PPARγ target genes. Importantly, we show that in common with disruption of PPARγ function, small interfering RNA-mediated reduction of Tip60 protein impairs differentiation of 3T3-L1 preadipocytes. Taken together, these findings qualify the acetyltransferase Tip60 as a novel adipogenic factor.

scholarly journals Thioredoxin-mediated Negative Autoregulation of Peroxisome Proliferator-activated Receptor α Transcriptional Activity

2006 ◽  
Vol 17 (4) ◽  
pp. 1822-1833 ◽  
Author(s):  
Guang-Hui Liu ◽  
Jing Qu ◽  
Xun Shen
Keyword(s):  
Negative Feedback ◽  
Active Sites ◽  
Feedback Loop ◽  
Transcriptional Activity ◽  
Target Genes ◽  
Negative Feedback Loop ◽  
Peroxisome Proliferator ◽  
Transactivation Domain ◽  
Mobility Shift ◽  
Peroxisome Proliferator Activated Receptor

PPARα, a member of the nuclear receptor superfamily, and thioredoxin, a critical redox-regulator in cells, were found to form a negative feedback loop, which autoregulates transcriptional activity of PPARα. Thioredoxin was identified as a target gene of PPARα. Activation of PPARα leads to increase of thioredoxin expression as well as its translocation from cytoplasm to nucleus, whereas ectopic overexpression of thioredoxin in the nucleus dramatically inhibited both constitutive and ligand-dependent PPARα activation. As PPARα-target genes, the expression of muscle carnitine palmitoyltransferase I, medium chain acyl CoA dehydrogenase, and apolipoprotein A-I were significantly down-regulated by nucleus-targeted thioredoxin at transcriptional or protein level. The suppression of PPARα transcriptional activity by Trx could be enhanced by overexpression of thioredoxin reductase or knockdown of thioredoxin-interacting protein, but abrogated by mutating the redox-active sites of thioredoxin. Mammalian one-hybrid assays showed that thioredoxin inhibited PPARα activity by modulating its AF-1 transactivation domain. It was also demonstrated by electrophoretic mobility-shift assay that thioredoxin inhibited the binding of PPARα to the PPAR-response element. Together, it is speculated that the reported negative-feedback loop may be essential for maintaining the homeostasis of PPARα activity.

scholarly journals The p400/Brd8 Chromatin Remodeling Complex Promotes Adipogenesis by Incorporating Histone Variant H2A.Z at PPARγ Target Genes

Endocrinology ◽  
2012 ◽  
Vol 153 (12) ◽  
pp. 5796-5808 ◽  
Author(s):  
Jean-Philippe Couture ◽  
Guylaine Nolet ◽  
Elaine Beaulieu ◽  
Richard Blouin ◽  
Nicolas Gévry
Keyword(s):  
Cell Differentiation ◽  
Rna Polymerase Ii ◽  
Target Genes ◽  
Histone Variant ◽  
Peroxisome Proliferator ◽  
Mature Adipocyte ◽  
Fat Cell ◽  
Promoter Regions ◽  
Peroxisome Proliferator Activated Receptor ◽  
Regulated Gene Expression

Abstract Adipogenesis, the biological process by which preadipocytes differentiate into mature fat cells, is coordinated by a tightly regulated gene expression program. Indeed, it has been reported that a large number of genetic events, from fat cell-specific transcription factors expression, such as the master regulator of fat cell differentiation peroxisome proliferator-activated receptor (PPAR)γ2 to epigenetic modifications, govern the acquisition of a mature adipocyte phenotype. Here, we provide evidence that the E1A-binding protein p400 (p400) complex subunit bromo-containing protein 8 (Brd8) plays an important role in the regulation of PPARγ target genes during adipogenesis by targeting and incorporating the histone variant H2A.Z in transcriptional regulatory regions. The results reported here indicate that expression of both Brd8 and p400 increases during fat cell differentiation. In addition, small hairpin RNA-mediated knockdown of Brd8 or H2A.Z completely abrogated the ability of 3T3-L1 preadipocyte to differentiate into mature adipocyte, as evidenced by a lack of lipid accumulation. Chromatin immunoprecipitation experiments also revealed that the knockdown of Brd8 blocked the accumulation of PPARγ, p400, and RNA polymerase II and prevented the incorporation of H2A.Z at two PPARγ target genes. Taken together, these results indicate that the incorporation of the histone variant H2A.Z at the promoter regions of PPARγ target genes by p400/Brd8 is essential to allow fat cell differentiation.

scholarly journals Wnt/β-catenin Pathway-Mediated PPARδ Expression during Embryonic Development Differentiation and Disease

2021 ◽  
Vol 22 (4) ◽  
pp. 1854
Author(s):  
Tabinda Sidrat ◽  
Zia-Ur Rehman ◽  
Myeong-Don Joo ◽  
Kyeong-Lim Lee ◽  
Il-Keun Kong
Keyword(s):  
Embryonic Development ◽  
Transcriptional Activation ◽  
Target Gene ◽  
Developmental Stages ◽  
Embryonic Stem ◽  
Hereditary Diseases ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Stem Cell Regulation ◽  
Early Developmental

The Wnt/β-catenin signaling pathway plays a crucial role in early embryonic development. Wnt/β-catenin signaling is a major regulator of cell proliferation and keeps embryonic stem cells (ESCs) in the pluripotent state. Dysregulation of Wnt signaling in the early developmental stages causes several hereditary diseases that lead to embryonic abnormalities. Several other signaling molecules are directly or indirectly activated in response to Wnt/β-catenin stimulation. The crosstalk of these signaling factors either synergizes or opposes the transcriptional activation of β-catenin/Tcf4-mediated target gene expression. Recently, the crosstalk between the peroxisome proliferator-activated receptor delta (PPARδ), which belongs to the steroid superfamily, and Wnt/β-catenin signaling has been reported to take place during several aspects of embryonic development. However, numerous questions need to be answered regarding the function and regulation of PPARδ in coordination with the Wnt/β-catenin pathway. Here, we have summarized the functional activation of the PPARδ in co-ordination with the Wnt/β-catenin pathway during the regulation of several aspects of embryonic development, stem cell regulation and maintenance, as well as during the progression of several metabolic disorders.

scholarly journals New Target Genes for the Peroxisome Proliferator-Activated Receptor-γ(PPARγ) Antitumour Activity: Perspectives from the Insulin Receptor

PPAR Research ◽  
2009 ◽  
Vol 2009 ◽  
pp. 1-8 ◽  
Author(s):  
Daniela P. Foti ◽  
Francesco Paonessa ◽  
Eusebio Chiefari ◽  
Antonio Brunetti
Keyword(s):  
Insulin Receptor ◽  
Target Genes ◽  
Tumour Progression ◽  
Antitumour Activity ◽  
Peptide Hormone ◽  
Nuclear Hormone Receptor ◽  
Peroxisome Proliferator ◽  
Preclinical Research ◽  
Peroxisome Proliferator Activated Receptor ◽  
Wide Range

The insulin receptor (IR) plays a crucial role in mediating the metabolic and proliferative functions triggered by the peptide hormone insulin. There is considerable evidence that abnormalities in both IR expression and function may account for malignant transformation and tumour progression in some human neoplasias, including breast cancer. PPARγis a ligand-activated, nuclear hormone receptor implicated in many pleiotropic biological functions related to cell survival and proliferation. In the last decade, PPARγagonists—besides their known action and clinical use as insulin sensitizers—have proved to display a wide range of antineoplastic effects in cells and tissues expressing PPARγ, leading to intensive preclinical research in oncology. PPARγand activators affect tumours by different mechanisms, involving cell proliferation and differentiation, apoptosis, antiinflammatory, and antiangiogenic effects. We recently provided evidence that PPARγand agonists inhibit IR by non canonical, DNA-independent mechanisms affecting IR gene transcription. We conclude that IR may be considered a new PPARγ“target” gene, supporting a potential use of PPARγagonists as antiproliferative agents in selected neoplastic tissues that overexpress the IR.

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