Identification of a peroxisome-proliferator-activated-receptor response element in the apolipoprotein E gene control region

2001 ◽  
Vol 357 (2) ◽  
pp. 521-527 ◽  
Author(s):  
Román GALETTO ◽  
Marta ALBAJAR ◽  
José I. POLANCO ◽  
Mario M. ZAKIN ◽  
José C. RODRÍGUEZ-REY
Keyword(s):  
Apolipoprotein E ◽  
Control Region ◽  
Intergenic Region ◽  
Apoe Gene ◽  
Luciferase Reporter ◽  
Gene Control ◽  
Peroxisome Proliferator ◽  
Response Element ◽  
Peroxisome Proliferator Activated Receptor ◽  
Apoe Mrna

Apolipoprotein E (apoE) is a protein involved in reverse cholesterol transport. Among other tissues, apoE is expressed in macrophages where its expression increases when macrophages develop into foam cells. It has been recently shown that peroxisome-proliferator-activated receptor gamma (PPARγ) is involved in this conversion. Northern-blot analysis was carried out in the macrophage cell line THP1 to determine whether apoE mRNA levels were regulated by ciglitazone, a PPARγ inducer. The results indicated that treatment with ciglitazone doubled the levels of apoE mRNA. To identify a possible PPARγ response element (PPRE), several portions of apoE gene control region were used to construct luciferase reporter plasmids. In U-87 MG cells, a 185bp fragment located in the apoE/apoCI intergenic region was sufficient to induce a 10-fold increase in the luciferase activity of the extract of cells co-transfected with a PPARγ expression plasmid. Subsequent analysis revealed the presence of a sequence with a high level of sequence similarity to the consensus PPRE. Mutations in this sequence resulted in a lack of functionality both in transient transfection and in electrophoretic-mobility-shift assays. These results demonstrated the presence of a functional PPRE in the apoE/apoCI intergenic region. These results have implications for the regulation of apoE gene expression and could be relevant for understanding the anti-atherogenic effect of thiazolidinediones.

scholarly journals Peroxisome Proliferator-Activated Receptor-γ Increases Adiponectin Secretion via Transcriptional Repression of Endoplasmic Reticulum Chaperone Protein ERp44

Endocrinology ◽  
2010 ◽  
Vol 151 (7) ◽  
pp. 3195-3203 ◽  
Author(s):  
Qinqiang Long ◽  
Ting Lei ◽  
Bin Feng ◽  
Changjun Yin ◽  
Dan Jin ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Transcriptional Repression ◽  
Energy Homeostasis ◽  
Luciferase Reporter ◽  
Peroxisome Proliferator ◽  
Response Element ◽  
Peroxisome Proliferator Activated Receptor ◽  
Ppar Γ ◽  
Pparγ Agonist ◽  
Peroxisome Proliferator Response Element

Adiponectin, an adipocyte-derived hormone, is a versatile player involved in the regulation of energy homeostasis, cardiovascular disease, and diabetes. Within adipocytes, adiponectin is retained in the lumen of the endoplasmic reticulum (ER) by binding to the thiol protein ER resident protein 44 kDa (ERp44), which is apparently regulated by the activation of nuclear receptor peroxisome proliferator-activated receptor (PPAR)-γ. However, the precise role of ERp44 in adiponectin secretion remains elusive. In the present study, we investigated the functional correlation between ERp44 and adiponectin in a pig model. The transcription of porcine ERp44 was regulated by PPARγ, which was consistent with the finding of putative peroxisome proliferator response element sites within ERp44 promoter. Using chromatin immunoprecipitation and luciferase reporter assays, we demonstrated that the transcription of porcine ERp44 is repressed through binding of PPARγ to a peroxisome proliferator response element site located between positions −981 and −1004 in its 5′-flanking region. In human embryonic kidney 293 cells stably transfected with cDNA encoding porcine adiponectin, the secretion of adiponectin was significantly up-regulated and the ERp44 mRNA was down-regulated observably, by either the treatment of PPARγ agonist rosiglitazone or the overexpression of PPARγ in these cells. Taken together, our results indicated that PPARγ is an essential regulatory factor for the transcriptional activity of ERp44, which in turn controls the secretion of adiponectin.

scholarly journals TGFβ1 Controls PPARγExpression, Transcriptional Potential, and Activity, in Part, through Smad3 Signaling in Murine Lung Fibroblasts

PPAR Research ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Allan Ramirez ◽  
Erin N. Ballard ◽  
Jesse Roman
Keyword(s):  
Transforming Growth Factor ◽  
Gene Promoter ◽  
Negative Regulator ◽  
Lung Fibroblasts ◽  
Luciferase Reporter ◽  
Peroxisome Proliferator ◽  
Reporter Expression ◽  
Peroxisome Proliferator Activated Receptor ◽  
3T3 Fibroblasts ◽  
Nih 3T3

Transforming growth factorβ1 (TGFβ1) promotes fibrosis by, among other mechanisms, activating quiescent fibroblasts into myofibroblasts and increasing the expression of extracellular matrices. Recent work suggests that peroxisome proliferator-activated receptorγ(PPARγ) is a negative regulator of TGFβ1-induced fibrotic events. We, however, hypothesized that antifibrotic pathways mediated by PPARγare influenced by TGFβ1, causing an imbalance towards fibrogenesis. Consistent with this, primary murine primary lung fibroblasts responded to TGFβ1 with a sustained downregulation of PPARγtranscripts. This effect was dampened in lung fibroblasts deficient in Smad3, a transcription factor that mediates many of the effects of TGFβ1. Paradoxically, TGFβ1 stimulated the activation of the PPARγgene promoter and induced the phosphorylation of PPARγin primary lung fibroblasts. The ability of TGFβ1 to modulate the transcriptional activity of PPARγwas then tested in NIH/3T3 fibroblasts containing a PPARγ-responsive luciferase reporter. In these cells, stimulation of TGFβ1 signals with a constitutively active TGFβ1 receptor transgene blunted PPARγ-dependent reporter expression induced by troglitazone, a PPARγactivator. Overexpression of PPARγprevented TGFβ1 repression of troglitazone-induced PPARγ-dependent gene transcription, whereas coexpression of PPARγand Smad3 transgenes recapitulated the TGFβ1 effects. We conclude that modulation of PPARγis controlled by TGFβ1, in part through Smad3 signals, involving regulation of PPARγexpression and transcriptional potential.

scholarly journals Cyclin G2 Regulates Adipogenesis through PPARγ Coactivation

Endocrinology ◽  
2010 ◽  
Vol 151 (11) ◽  
pp. 5247-5254 ◽  
Author(s):  
Victor Aguilar ◽  
Jean-Sébastien Annicotte ◽  
Xavier Escote ◽  
Joan Vendrell ◽  
Dominique Langin ◽  
...  
Keyword(s):  
Adipocyte Differentiation ◽  
Luciferase Reporter ◽  
Peroxisome Proliferator ◽  
Mrna Levels ◽  
Cell Cycle Regulators ◽  
Luciferase Reporter Gene ◽  
Peroxisome Proliferator Activated Receptor ◽  
Cyclin G2 ◽  
Regulatory Effects

Cell cycle regulators such as cyclins, cyclin-dependent kinases, or retinoblastoma protein play important roles in the differentiation of adipocytes. In the present paper, we investigated the role of cyclin G2 as a positive regulator of adipogenesis. Cyclin G2 is an unconventional cyclin which expression is up-regulated during growth inhibition or apoptosis. Using the 3T3-F442A cell line, we observed an up-regulation of cyclin G2 expression at protein and mRNA levels throughout the process of cell differentiation, with a further induction of adipogenesis when the protein is transiently overexpressed. We show here that the positive regulatory effects of cyclin G2 in adipocyte differentiation are mediated by direct binding of cyclin G2 to peroxisome proliferator-activated receptor γ (PPARγ), the key regulator of adipocyte differentiation. The role of cyclin G2 as a novel PPARγ coactivator was further demonstrated by chromatin immunoprecipitation assays, which showed that the protein is present in the PPARγ-responsive element of the promoter of aP2, which is a PPARγ target gene. Luciferase reporter gene assays, showed that cyclin G2 positively regulates the transcriptional activity of PPARγ. The role of cyclin G2 in adipogenesis is further underscored by its increased expression in mice fed a high-fat diet. Taken together, our results demonstrate a novel role for cyclin G2 in the regulation of adipogenesis.

scholarly journals Identification of a Functional Peroxisome Proliferator-Activated Receptor Response Element in the Rat Catalase Promoter

2002 ◽  
Vol 16 (12) ◽  
pp. 2793-2801 ◽  
Author(s):  
Geoffrey D. Girnun ◽  
Frederick E. Domann ◽  
Steven A. Moore ◽  
Mike E. C. Robbins
Keyword(s):  
Reactive Oxygen Species ◽  
Transcription Factors ◽  
Inflammatory Response ◽  
Reactive Oxygen ◽  
Peroxisome Proliferator ◽  
Oxygen Species ◽  
Response Element ◽  
Peroxisome Proliferator Activated Receptor ◽  
Promoter Deletion Analysis

Abstract Peroxisomal proliferator-activated receptor (PPAR)γ has been shown to decrease the inflammatory response via transrepression of proinflammatory transcription factors. However, the identity of PPARγ responsive genes that decrease the inflammatory response has remained elusive. Because generation of the reactive oxygen species hydrogen peroxide (H2O2) plays a role in the inflammatory process and activation of proinflammatory transcription factors, we wanted to determine whether the antioxidant enzyme catalase might be a PPARγ target gene. We identified a putative PPAR response element (PPRE) containing the canonical direct repeat 1 motif, AGGTGA-A-AGTTGA, in the rat catalase promoter. In vitro translated PPARγ and retinoic X receptor-α proteins were able to bind to the catalase PPRE. Promoter deletion analysis revealed that the PPRE was functional, and a heterologous promoter construct containing a multimerized catalase PPRE demonstrated that the PPRE was necessary and sufficient for PPARγ-mediated activation. Treatment of microvascular endothelial cells with PPARγ ligands led to increases in catalase mRNA and activity. These results demonstrate that PPARγ can alter catalase expression; this occurs via a PPRE in the rat catalase promoter. Thus, in addition to transrepression of proinflammatory transcription factors, PPARγ may also be modulating catalase expression, and hence down-regulating the inflammatory response via scavenging of reactive oxygen species.

scholarly journals Peroxisome Proliferator-Activated ReceptorγRegulates the Expression of Lipid Phosphate Phosphohydrolase 1 in Human Vascular Endothelial Cells

PPAR Research ◽  
2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Yazi Huang ◽  
Beilei Zhao ◽  
Yahan Liu ◽  
Nanping Wang
Keyword(s):  
Endothelial Cells ◽  
Umbilical Vein ◽  
Mrna Level ◽  
Site Directed Mutagenesis ◽  
Luciferase Reporter ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Lipid Phosphate ◽  
Lipid Phosphate Phosphohydrolase

Lipid phosphate phosphohydrolase 1 (LPP1), a membrane ectophosphohydrolase regulating the availability of bioactive lipid phosphates, plays important roles in cellular signaling and physiological processes such as angiogenesis and endothelial migration. However, the regulated expression of LPP1 remains largely unknown. Here, we aimed to examine a role of peroxisome proliferator-activated receptorγ(PPARγ) in the transcriptional control ofLPP1gene expression. In human umbilical vein endothelial cells (HUVECs), quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) demonstrated that activation of PPARγincreased the mRNA level of LPP1. Chromatin immunoprecipitation assay showed that PPARγbinds to the putative PPAR-responsive elements (PPREs) within the 5′-flanking region of the humanLPP1gene. Genomic fragment containing 1.7-kilobase of the promoter region was cloned by using PCR. The luciferase reporter assays demonstrated that overexpression of PPARγand rosiglitazone, a specific ligand for PPARγ, could significantly upregulate the reporter activity. However, site-directed mutagenesis of the PPRE motif abolished the induction. In conclusion, our results demonstrated that PPARγtranscriptionally activated the expression ofLPP1gene in ECs, suggesting a potential role of PPARγin the metabolism of phospholipids.

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