scholarly journals Statins Activate Human PPAR Promoter and Increase PPAR mRNA Expression and Activation in HepG2 Cells

PPAR Research ◽  
2008 ◽  
Vol 2008 ◽  
pp. 1-11 ◽  
Author(s):  
Makoto Seo ◽  
Ikuo Inoue ◽  
Masaaki Ikeda ◽  
Takanari Nakano ◽  
Seiichiro Takahashi ◽  
...  
Keyword(s):  
Mrna Expression ◽  
Hepg2 Cells ◽  
Promoter Activity ◽  
Transcriptional Activity ◽  
Statin Treatment ◽  
Expression Vectors ◽  
Peroxisome Proliferator ◽  
Dependent Manner ◽  
Peroxisome Proliferator Activated Receptor ◽  
Protein Levels

Statins increase peroxisome proliferator-activated receptor (PPAR) mRNA expression, but the mechanism of this increased PPAR production remains elusive. To examine the regulation of PPAR production, we examined the effect of 7 statins (atorvastatin, cerivastatin, fluvastatin, pitavastatin, pravastatin, rosuvastatin, and simvastatin) on human PPAR promoter activity, mRNA expression, nuclear protein levels, and transcriptional activity. The main results are as follows. (1) Majority of statins enhanced PPAR promoter activity in a dose-dependent manner in HepG2 cells transfected with the human PPAR promoter. This enhancement may be mediated by statin-induced HNF-4. (2) PPAR mRNA expression was increased by statin treatment. (3) The PPAR levels in nuclear fractions were increased by statin treatment. (4) Simvastatin, pravastatin, and cerivastatin markedly enhanced transcriptional activity in 293T cells cotransfected with acyl-coenzyme A oxidase promoter and PPAR/RXR expression vectors. In summary, these data demonstrate that PPAR production and activation are upregulated through the PPAR promoter activity by statin treatment.

Peroxisomal bifunctional enzyme binds and activates the activationfunction-1 region of the peroxisome proliferator-activated receptor α

2001 ◽  
Vol 353 (2) ◽  
pp. 253-258 ◽  
Author(s):  
Cristiana E. JUGE-AUBRY ◽  
Stéphane KUENZLI ◽  
Jean-Charles SANCHEZ ◽  
Denis HOCHSTRASSER ◽  
Christoph A. MEIER
Keyword(s):  
Amino Acids ◽  
Transcriptional Activity ◽  
Hormone Receptors ◽  
Affinity Purification ◽  
Fold Increase ◽  
Activation Function ◽  
Bifunctional Enzyme ◽  
Peroxisome Proliferator ◽  
Dependent Manner ◽  
Peroxisome Proliferator Activated Receptor

The transcriptional activity of peroxisome proliferator-activated receptors (PPARs), and of nuclear hormone receptors in general, is subject to modulation by cofactors. However, most currently known co-activating proteins interact in a ligand-dependent manner with the C-terminal ligand-regulated activation function (AF)-2 domain of nuclear receptors. Since PPARα exhibits a strong constitutive transactivating function contained within an N-terminal AF-1 region, it can be speculated that a different set of cofactors might interact with this region of PPARs. An affinity purification approach was used to identify the peroxisomal enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase (bifunctional enzyme, BFE) as a protein which strongly and specifically interacted with the N-terminal 92 amino acids of PPARα. ProteinŐprotein interaction assays with the cloned BFE confirmed this interaction, which could be mapped to amino acids 307Ő514 of the BFE and the N-terminal 70 amino acids of PPARα. Moreover, transient transfection experiments in hepatoma cells revealed a 2.2-fold increase in the basal and ligand-stimulated transcriptional activity of PPARα in the presence of BFE. This stimulatory effect is preferentially observed for the PPARα isoform and it is significantly stronger (4.8-fold) in non-hepatic cells, which presumably express lower levels of endogenous BFE. Hence, the BFE represents the first known cofactor capable of activating the AF-1 domain of PPAR without requiring additional regions of this receptor. These data are compatible with a model whereby the PPAR-regulated BFE is able to modulate its own expression through an enhancement of the activity of PPARα, representing a novel peroxisomalŐnuclear feed-forward regulatory loop.

scholarly journals Homeostatic levels of SRC-2 and SRC-3 promote early human adipogenesis

2011 ◽  
Vol 192 (1) ◽  
pp. 55-67 ◽  
Author(s):  
Sean M. Hartig ◽  
Bin He ◽  
Weiwen Long ◽  
Benjamin M. Buehrer ◽  
Michael A. Mancini
Keyword(s):  
Transcriptional Activity ◽  
Adipocyte Differentiation ◽  
Cellular Heterogeneity ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Human Adipocyte ◽  
Lipogenic Gene ◽  
Protein Levels ◽  
High Content Analysis ◽  
Early Human

The related coactivators SRC-2 and SRC-3 interact with peroxisome proliferator activated receptor γ (PPARγ) to coordinate transcriptional circuits to promote adipogenesis. To identify potential coactivator redundancy during human adipogenesis at single cell resolution, we used high content analysis to quantify links between PPARγ, SRC-2, SRC-3, and lipogenesis. Because we detected robust increases and significant cell–cell heterogeneity in PPARγ and lipogenesis, without changes in SRC-2 or SRC-3, we hypothesized that permissive coregulator levels comprise a necessary adipogenic equilibrium. We probed this equilibrium by down-regulating SRC-2 and SRC-3 while simultaneously quantifying PPARγ. Individual or joint knockdown equally inhibits lipid accumulation by preventing lipogenic gene engagement, without affecting PPARγ protein levels. Supporting dominant, pro-adipogenic roles for SRC-2 and SRC-3, SRC-1 knockdown does not affect adipogenesis. SRC-2 and SRC-3 knockdown increases the proportion of cells in a PPARγhi/lipidlo state while increasing phospho-PPARγ–S114, an inhibitor of PPARγ transcriptional activity and adipogenesis. Together, we demonstrate that SRC-2 and SRC-3 concomitantly promote human adipocyte differentiation by attenuating phospho-PPARγ–S114 and modulating PPARγ cellular heterogeneity.

Abstract 1729: PPARγ Regulates ABCG1 Expression in Macrophages via LXR-Driven Dual Promoters

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Makoto Ayaori ◽  
Masatsune Ogura ◽  
Kazuhiro Nakaya ◽  
Tetsuya Hisada ◽  
Shun-ichi Takiguchi ◽  
...  
Keyword(s):  
Cholesterol Efflux ◽  
Density Lipoprotein ◽  
Peroxisome Proliferator ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Peroxisome Proliferator Activated Receptor ◽  
Protein Levels ◽  
Exon 1 ◽  
Dual Promoters ◽  
Sirna Knockdown

ATP binding cassette transporter G1 (ABCG1), which is expressed in macrophages, has been implicated in the efflux of cholesterol to high density lipoprotein. Peroxisome proliferator-activated receptor γ (PPARγ) has been reported to be involved in cholesterol efflux from macrophages, and increased expression of ABCG1 via liver receptor X (LXR)-dependent and independent pathways. However, the mechanisms by which ABCG1 expression is increased by PPARγ have not been fully characterized. We observed that pioglitazone, a PPARγ ligand, increases cholesterol efflux from THP-1 macrophages, as well as ABCG1 mRNA and protein levels. Treatment with actinomycin D abolished the inducible effect of pioglitazone on ABCG1, indicating that pioglitazone transcriptionally activated ABCG1 expression. To clarify how pioglitazone regulates ABCG1 expression, we investigated promoter activity using reporter constructs containing human ABCG1 promoter A and B (located upstream of exon 1 and 5, respectively), with or without mutated LXR-binding sites. The results indicated that pioglitazone activated both promoters in an LXR-dependent manner. We also observed that pioglitazone increased two major transcripts driven by promoter A and B using specific primers for each transcript. To determine whether PPARγ and LXRα were involved in these effects of pioglitazone, we performed siRNA-knockdown of PPARγ and LXRα in macrophages, which resulted in 75% and 91% decreases in PPARγ and LXRα mRNA levels, respectively. PPARγ and LXRα-knockdown, respectively, completely or partially abolished pioglitazone-induced ABCG1 expression. In conclusion, these results suggest that pioglitazone transcriptionally increased ABCG1 expression in macrophages by activating dual promoters in an LXR-dependent manner. Further studies are needed to assess LXR-independent mechanisms for the stimulatory effect of pioglitazone on ABCG1.

Molecular mechanism of 1,25-dihydroxyvitamin D3 inhibition of adipogenesis in 3T3-L1 cells

2006 ◽  
Vol 290 (5) ◽  
pp. E916-E924 ◽  
Author(s):  
Juan Kong ◽  
Yan Chun Li
Keyword(s):  
Cell Differentiation ◽  
Molecular Mechanism ◽  
Regulatory Element ◽  
Peroxisome Proliferator ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Dihydroxyvitamin D3 ◽  
Peroxisome Proliferator Activated Receptor ◽  
Protein Levels

We have investigated the molecular mechanism whereby 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] inhibits adipogenesis in vitro. 1,25(OH)2D3 blocks 3T3-L1 cell differentiation into adipocytes in a dose-dependent manner; however, the inhibition is ineffective 24–48 h after the differentiation is initiated, suggesting that 1,25(OH)2D3 inhibits only the early events of the adipogenic program. Treatment of 3T3-L1 cells with 1,25(OH)2D3 does not block the mitotic clonal expansion or C/EBPβ induction; rather, 1,25(OH)2D3 blocks the expression of C/EBPα, peroxisome proliferator-activated receptor-γ (PPARγ), sterol regulatory element-binding protein-1, and other downstream adipocyte markers. The inhibition by 1,25(OH)2D3 is reversible, since removal of 1,25(OH)2D3 from the medium restores the adipogenic process with only a temporal delay. Interestingly, although the vitamin D receptor (VDR) protein is barely detectable in 3T3-L1 preadipocytes, its levels are dramatically increased during the early phase of adipogenesis, peaking at 4–8 h and subsiding afterward throughout the rest of the differentiation program; 1,25(OH)2D3 treatment appears to stabilize the VDR protein levels. Consistently, adenovirus-mediated overexpression of human (h) VDR in 3T3-L1 cells completely blocks the adipogenic program, confirming that VDR is inhibitory. Inhibition of adipocyte differentiation by 1,25(OH)2D3 is ameliorated by troglitazone, a specific PPARγ antagonist; conversely, hVDR partially suppresses the transacting activity of PPARγ but not of C/EBPβ or C/EBPα. Moreover, 1,25(OH)2D3 markedly suppresses C/EBPα and PPARγ mRNA levels in mouse epididymal fat tissue culture. Taken together, these data indicate that the blockade of 3T3-L1 cell differentiation by 1,25(OH)2D3 occurs at the postclonal expansion stages and involves direct suppression of C/EBPα and PPARγ upregulation, antagonization of PPARγ activity, and stabilization of the inhibitory VDR protein.

scholarly journals The effect of omega3 fatty acid supplementation on PPARγ and UCP2 expressions, resting energy expenditure, and appetite in athletes

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Sara Moradi ◽  
Mohamadreza Alivand ◽  
Yaser KhajeBishak ◽  
Mohamad AsghariJafarabadi ◽  
Maedeh Alipour ◽  
...  
Keyword(s):  
Energy Expenditure ◽  
Mrna Expression ◽  
Resting Energy Expenditure ◽  
Peroxisome Proliferator ◽  
Mrna Levels ◽  
Double Blind ◽  
Peroxisome Proliferator Activated Receptor ◽  
Protein Levels ◽  
Ucp2 Mrna ◽  
Resting Energy

Abstract Background Omega3 fatty acids as a ligand of energy-related genes, have a role in metabolism, and energy expenditure. These effects are due to changes in the expression of peroxisome proliferator-activated receptor-gamma (PPARγ) and uncoupling protein2 (UCP2). This study evaluated the effect of omega3 supplements on PPARγ mRNA expression and UCP2 mRNA expression and protein levels, as regulators of energy metabolism, resting energy expenditure (REE), and appetite in athletes. Methods In a 3-week double-blind RCT in Tabriz, Iran, in 2019, 36 male athletes, age 21.86 (±3.15) y with 16.17 (±5.96)% body fat were randomized to either an intervention (2000 mg/day omega3; EPA: 360, DHA: 240) or placebo (2000 mg/day edible paraffin) groups. Appetite and REE were assessed before and after the intervention. PPARγ and UCP2 mRNA expression and UCP2 protein levels in blood were evaluated by standard methods. Results Results showed PPARγ mRNA levels, and UCP2 mRNA and protein levels increased in omega3 group (p < 0.05), as did REE (p < 0.05). Also, differences in the sensation of hunger or satiety were significant (p < 0.05). Conclusions Our findings showed that omega3 supplementation leads to the up-regulation of PPARγ and UCP2 expressions as the indicators of metabolism in healthy athletes.

Oleic acid-induced perilipin 5 expression and lipid droplets formation are regulated by the PI3K/PPARα pathway in HepG2 cells

2019 ◽  
Vol 44 (8) ◽  
pp. 840-848 ◽  
Author(s):  
Wenxia Zhong ◽  
Bin Fan ◽  
Huiying Cong ◽  
Tianyu Wang ◽  
Jianqiu Gu
Keyword(s):  
Oleic Acid ◽  
Hepg2 Cells ◽  
Lipid Droplets ◽  
Peroxisome Proliferator ◽  
Dependent Manner ◽  
Peroxisome Proliferator Activated Receptor ◽  
Nonalcoholic Fatty Liver ◽  
Pi3k Inhibitor Ly294002 ◽  
Perilipin 5 ◽  
Phosphoinositide 3 Kinase

Perilipin 5 (Plin5), a member of the PAT (Perilipin, ADRP, and Tip47) protein family, has been implicated in the regulation of cellular neutral lipid accumulation in nonalcoholic fatty liver diseases. However, the underlying regulatory mechanisms of Plin5 are not clear. The goal of the present study was to explore the mechanism of oleic acid (OA)-induced Plin5 expression in HepG2 cells. We found that the expression of Plin5 was increased during OA-induced lipid droplets formation in a dose- and time-dependent manner. During this process of OA-stimulated lipid droplets formation, peroxisome proliferator-activated receptor alpha (PPARα) was also upregulated. When PPARα activation was blocked by GW6471, OA-induced Plin5 expression and lipid droplets formation were effectively ablated. We further found that the phosphoinositide 3-kinase (PI3K) inhibitor LY294002 was able to downregulate both PPARα and Plin5 expression and lipid droplets formation. Thus, we concluded that PI3K may, at least in part, act upstream of PPARα to regulate Plin5 expression and lipid droplets formation in HepG2 cells.

scholarly journals Peroxisome Proliferator-Activated Receptor-γ(PPAR-γ) Agonists Attenuate the Profibrotic Response Induced by TGF-β1 in Renal Interstitial Fibroblasts

2007 ◽  
Vol 2007 ◽  
pp. 1-7 ◽  
Author(s):  
Weiming Wang ◽  
Feng Liu ◽  
Nan Chen
Keyword(s):  
Protein Expression ◽  
Mrna Expression ◽  
Kidney Diseases ◽  
Smooth Muscle Actin ◽  
Tissue Growth ◽  
Time Dependent ◽  
Peroxisome Proliferator ◽  
Dependent Manner ◽  
Peroxisome Proliferator Activated Receptor ◽  
Ppar Γ

Background.Studies have shown that peroxisome proliferator-activated receptor-γ(PPAR-γ) agonists could ameliorate renal fibrotic lesions in both diabetic nephropathy and nondiabetic chronic kidney diseases. In order to elucidate the antifibrotic mechanism of PPAR-γagonists, we investigated the effects of PPAR-γactivation on TGF-β1-induced renal interstitial fibroblasts.Methods.In rat renal interstitial fibroblasts (NRK/49F), the mRNA expression of TGF-β1-inducedα-smooth muscle actin (α-SMA), connective tissue growth factor (CTGF), fibronectin (FN) and collagen type III (Col III) were observed by reverse transcriptase-polymerase chain reaction (RT-PCR). The protein expressions of FN and Smads were observed by Western blot.Results.In NRK/49F, TGF-β1 enhanced CTGF, FN and Col III mRNA expression in a dose- and time-dependent manner.α-SMA, CTGF, FN and Col III mRNA and FN protein expression in 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2)-troglitazone- and ciglitazone-pretreated groups, respectively, were significantly decreased compared with the TGF-β1-stimulated group. TGF-β1 (5 ng/mL) enhanced p-Smad2/3 protein expression in a time-dependent manner. Compared with the TGF-β1-stimulated group, p-Smad2/3 protein induced by TGF-β1 in PPAR-γagonists-pretreated groups significantly decreased with no statistical difference amongst the three pretreated groups.Conclusion.PPAR-γagonists could inhibit TGF-β1-induced renal fibroblast activation, CTGF expression and ECM synthesis through abrogating the TGF-β1/Smads signaling pathway.

scholarly journals PPARα: A Master Regulator of Bilirubin Homeostasis

PPAR Research ◽  
2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Cyril Bigo ◽  
Jenny Kaeding ◽  
Diala El Husseini ◽  
Iwona Rudkowska ◽  
Mélanie Verreault ◽  
...  
Keyword(s):  
Hepg2 Cells ◽  
Umbilical Vein ◽  
Human Hepatocytes ◽  
Clinical Implications ◽  
Protein Accumulation ◽  
Peroxisome Proliferator ◽  
Activity Levels ◽  
Peroxisome Proliferator Activated Receptor ◽  
Biliverdin Reductase ◽  
Protein Levels

Hypolipidemic fibrates activate the peroxisome proliferator-activated receptor (PPAR)αto modulate lipid oxidation and metabolism. The present study aimed at evaluating how 3 PPARαagonists, namely, fenofibrate, gemfibrozil, and Wy14,643, affect bilirubin synthesis and metabolism. Human umbilical vein epithelial cells (HUVEC) and coronary artery smooth muscle cells (CASMC) were cultured in the absence or presence of the 3 activators, and mRNA, protein, and/or activity levels of the bilirubin synthesizing heme oxygenase- (HO-) 1 and biliverdin reductase (BVR) enzymes were determined. Human hepatocytes (HH) and HepG2 cells sustained similar treatments, except that the expression of the bilirubin conjugating UDP-glucuronosyltransferase (UGT) 1A1 enzyme and multidrug resistance-associated protein (MRP) 2 transporter was analyzed. In HUVECs, gemfibrozil, fenofibrate, and Wy14,643 upregulated HO-1 mRNA expression without affecting BVR. Wy14,643 and fenofibrate also caused HO-1 protein accumulation, while gemfibrozil and fenofibrate favored the secretion of bilirubin in cell media. Similar positive regulations were also observed with the 3 PPARαligands in CASMCs where HO-1 mRNA and protein levels were increased. In HH and HepG2 cells, both UGT1A1 and MRP2 transcripts were also accumulating. These observations indicate that PPARαligands activate bilirubin synthesis in vascular cells and metabolism in liver cells. The clinical implications of these regulatory events are discussed.

scholarly journals miR-27b promotes type II collagen expression by targetting peroxisome proliferator-activated receptor-γ2 during rat articular chondrocyte differentiation

2018 ◽  
Vol 38 (1) ◽  
Author(s):  
Jinying Xu ◽  
Shuang Lv ◽  
Yi Hou ◽  
Kan Xu ◽  
Dongjie Sun ◽  
...  
Keyword(s):  
Articular Cartilage ◽  
Type Ii Collagen ◽  
Luciferase Reporter ◽  
Peroxisome Proliferator ◽  
Dependent Manner ◽  
Type Ii ◽  
Peroxisome Proliferator Activated Receptor ◽  
Protein Levels ◽  
Pparγ Agonist ◽  
Gene Assay

MicroRNAs (miRNAs) play an essential role in articular cartilage development and growth. However, the exact mechanisms involved in this process remain unknown. In the present study, we investigated the biological functions of miR-27b during hypertrophic differentiation of rat articular chondrocytes. Based on in situ hybridization and immunohistochemistry, we report that miR-27b expression is reduced in the hypertrophic zone of articular cartilage, but expression of peroxisome proliferator-activated receptor γ (Pparγ) is increased. Dual-luciferase reporter gene assay and Western blot analysis demonstrated that Pparγ2 is a target of miR-27b. Overexpression of miR-27b inhibited expression of Pparγ2, as well as type X collagen (Col10a1) and matrix metalloproteinase 13 (Mmp13), while significantly promoting the expression of Sex-determining Region-box 9 (Sox9) and type II collagen (Col2a1) at both the mRNA and protein levels. Rosiglitazone, a Pparγ agonist, suppressed Col2a1 expression, while promoting expression of runt-related transcription factor 2 (Runx2) and Col10a1 in a concentration-dependent manner. siRNA-mediated knockdown of Pparγ2 caused an increase in protein levels of Col2a1. The present study demonstrates that miR-27b regulates chondrocyte hypertrophy in part by targetting Pparγ2, and that miR-27b may have important therapeutic implications in cartilage diseases.

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