scholarly journals The Pal3 Promoter Sequence Is Critical for the Regulation of Human Renin Gene Transcription by Peroxisome Proliferator-Activated Receptor-γ

Endocrinology ◽  
2008 ◽  
Vol 149 (9) ◽  
pp. 4647-4657 ◽  
Author(s):  
Vladimir T. Todorov ◽  
Michael Desch ◽  
Thomas Schubert ◽  
Armin Kurtz

We recently reported that human renin gene transcription is stimulated by the nuclear receptor peroxisome proliferator-activated receptor (PPAR)-γ in the renin-producing cell line Calu-6. The effect of PPARγ was mapped to two sequences in the renin promoter: a direct repeat hormone response element (HRE), which is related to the classical PPAR response element (PPRE) and a nonconsensus palindromic element with a 3-bp spacer (Pal3). We now find that PPARγ binds to the renin HRE. Neither the human renin HRE nor the consensus PPRE was sufficient to attain the maximal stimulation of renin promoter activity by the PPARγ agonist rosiglitazone. In contrast, the human renin Pal3 element mediates both the full PPARγ-dependent activation of transcription and the PPARγ-driven basal renin gene transcription. The human renin Pal3 sequence was found to selectively bind PPARγ and the retinoid X receptor-α from Calu-6 nuclear extracts. This is in contrast to the consensus PPRE, which can bind other nuclear proteins. PPARγ knockdown paradoxically did not attenuate the stimulation of the endogenous renin gene expression by rosiglitazone. Similarly, a deficiency of PPARγ did not attenuate the activation of the minimal human renin promoter, which contains the endogenous Pal3 motif. However, when the human renin Pal3 site was replaced by the consensus PPRE sequence, PPARγ knockdown abrogated the effect of rosiglitazone on renin promoter activity. Thus, the human renin Pal3 site appears to be critical for the PPARγ-dependent regulation of gene expression by mediating maximal transcription activation, particularly at the low cellular level of PPARγ.

2021 ◽  
Author(s):  
Fubiao Shi ◽  
Zoltan Simandi ◽  
Laszlo Nagy ◽  
Sheila Collins

AbstractIn addition to their established role to maintain blood pressure and fluid volume, the cardiac natriuretic peptides (NPs) can stimulate adipocyte lipolysis and control the brown fat gene program of nonshivering thermogenesis. The NP “clearance” receptor C (NPRC) functions to clear NPs from the circulation via peptide internalization and degradation and thus is an important regulator of NP signaling and adipocyte metabolism. It is well appreciated that the Nprc gene is highly expressed in adipose tissue and is dynamically regulated with nutrition and environmental changes. However, the molecular basis for how Nprc gene expression is regulated is still poorly understood. Here we identified Peroxisome Proliferator-Activated Receptor gamma (PPARγ) as a transcriptional regulator of Nprc expression in mouse adipocytes. During 3T3-L1 adipocyte differentiation, levels of Nprc expression increase in parallel with PPARγ induction. Rosiglitazone, a classic PPARγ agonist, increases, while siRNA knockdown of PPARγ reduces, Nprc expression in 3T3-L1 adipocytes. We demonstrate that PPARγ controls Nprc gene expression in adipocytes through its long-range distal enhancers. Furthermore, the induction of Nprc expression in adipose tissue during high-fat diet feeding is associated with increased PPARγ enhancer activity. Our findings define PPARγ as a mediator of adipocyte Nprc gene expression and establish a new connection between PPARγ and the control of adipocyte NP signaling in obesity.


Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Mandy Bloch ◽  
Anna Foryst-Ludwig ◽  
Thomas Unger ◽  
Ulrich Kintscher

The study aimed to identify new nuclear cofactors for PPARgamma (peroxisome proliferator-activated receptor gamma)-dependent gene transcription in human aortic smooth muscle cells (HASMC) in order to develop new PPARgamma-ligands with improved clinical safety in the absence of deleterious cardiovascular side effects. Using an Oligo GEArray® Human Nuclear Receptors and Coregulators Microarray for gene expression profiling, we identified the transcriptional regulator and chromatin modifying High Mobility Group (HMG) A1 protein highly expressed in unstimulated HASMC. PPARgamma-dependent gene regulation was studied by analysis of PMA-induced MMP-9 (matrix metalloproteinase 9) expression ± pioglitazone (pio 10μM). PMA (50ng/ml) stimulated MMP-9 mRNA expression by 46.3±22.3-fold (p<0.05 vs. vehicle) which was markedly blocked by pio (10μM: 17.4±4.8-fold vs. PMA alone p<0.05). Pio also blocked PMA-induced MMP-9 promoter activity by 45% in transactivation assays in HEK293 using a pGL3-MMP-9 2.2 kb construct. To evaluate the role of HMGA1, gene silencing experiments with siRNA for HMGA1 were performed (91 % in HASMC and 80.2% in HEK293 reduction of HMGA1 protein expression). HMGA1 siRNA completely abolished PPARgamma-mediated MMP9-mRNA repression (control siRNA: pio-mediated MMP-9 regulation vs. PMA alone: −66.8 % in HASMC and −59.3% in HEK293 p<0.01; HMGA1 siRNA: pio-mediated MMP-9 regulation vs. PMA alone: +10.7 % in HASMC and +14.7% in HEK293 vs. PMA alone; p=n.s.). Knockdown of HMGA1 expression reverse trans-repression of MMP9 by PPARgamma in HASMCs. By using ChIP assay we could demonstrate that pio-induced PPARgamma activation leads to a potent recruitment of PPARgamma (3.0 fold vs.1.15 fold PMA alone) and HMGA1 complexes (1.24 fold vs. 0.0 fold PMA alone) to the MMP9 promoter in HASMC. In consonance with reduced promoter activity, RNA-Polymerase II was removed from the MMP9 promoter by pio (0.08 fold vs 1.04 fold PMA alone). In conclusion, HMGA1 is required for PPARgamma-mediated repression of MMP-9 gene transcription. Ligand-induced HMGA1-PPARgamma interactions might be an important determinant for ligand-specific anti-atherosclerotic actions.


Hypertension ◽  
2007 ◽  
Vol 50 (5) ◽  
pp. 939-944 ◽  
Author(s):  
Vladimir T. Todorov ◽  
Michael Desch ◽  
Nina Schmitt-Nilson ◽  
Anelia Todorova ◽  
Armin Kurtz

2001 ◽  
Vol 276 (15) ◽  
pp. 12440-12448 ◽  
Author(s):  
Kotha Subbaramaiah ◽  
Derrick T. Lin ◽  
Janice C. Hart ◽  
Andrew J. Dannenberg

We investigated whether peroxisome proliferator-activated receptor γ (PPARγ) ligands (ciglitazone, troglitazone, and 15-deoxy-Δ12,14prostaglandin J2) inhibited cyclooxygenase-2 (COX-2) induction in human epithelial cells. Ligands of PPARγ inhibited phorbol ester (phorbol 12-myristate 13-acetate, PMA)-mediated induction of COX-2 and prostaglandin E2synthesis. Nuclear run-offs revealed increased rates ofCOX-2transcription after treatment with PMA, an effect that was inhibited by PPARγ ligands. PMA-mediated induction ofCOX-2promoter activity was inhibited by PPARγ ligands; this suppressive effect was prevented by overexpressing a dominant negative form of PPARγ or a PPAR response element decoy oligonucleotide. The stimulatory effects of PMA were mediated by a cyclic AMP response element in theCOX-2promoter. Treatment with PMA increased activator protein-1 (AP-1) activity and the binding of c-Jun, c-Fos, and ATF-2 to the cyclic AMP response element, effects that were blocked by PPARγ ligands. These findings raised questions about the mechanism underlying the anti-AP-1 effect of PPARγ ligands. The induction of c-Jun by PMA was blocked by PPARγ ligands. Overexpression of either c-Jun or CREB-binding protein/p300 partially relieved the suppressive effect of PPARγ ligands. When CREB-binding protein and c-Jun were overexpressed together, the ability of PPARγ ligands to suppress PMA-mediated induction ofCOX-2promoter activity was essentially abrogated. Bisphenol A diglycidyl ether, a compound that binds to PPARγ but lacks the ability to activate transcription, also inhibited PMA-mediated induction of AP-1 activity and COX-2. Taken together, these findings are likely to be important for understanding the anti-inflammatory and anti-cancer properties of PPARγ ligands.


Endocrinology ◽  
2004 ◽  
Vol 145 (11) ◽  
pp. 4948-4956 ◽  
Author(s):  
Masataka Kudo ◽  
Akira Sugawara ◽  
Akira Uruno ◽  
Kazuhisa Takeuchi ◽  
Sadayoshi Ito

Abstract TNFα is known to inhibit adipocyte differentiation and induce insulin resistance. Moreover, TNFα is known to down-regulate peroxisome proliferator-activated receptor (PPAR)γ2, an adipocyte-specific nuclear receptor of insulin-sensitizer thiazolidinediones. To clarify molecular mechanisms of TNFα- mediated PPARγ2 down-regulation, we here examined the effect of TNFα on transcription regulation of PPARγ2 gene expression during the early stage of adipocyte differentiation. 3T3-L1 preadipocytes (2 d after 100% confluent) were incubated in a differentiation mixture (dexamethasone, insulin, 3-isobutyl-1-methlxanthine), with or without 50 ng/ml TNFα, for 24 h. TNFα significantly decreased PPARγ2 expression both at mRNA and protein levels (to ∼40%), as well as aP2 mRNA expression. The mouse PPARγ2 gene promoter region (2.2-kb) was isolated and was used for luciferase reporter assays by transient transfection. TNFα significantly suppressed PPARγ2 gene transcription (to ∼50%), and deletion analyses demonstrated that the suppression was mediated via CCAAT/enhancer-binding protein (C/EBP) binding elements at the −320/−340 region of the promoter. Moreover, TNFα significantly decreased expression of C/EBPδ mRNA and protein levels (to ∼40%). EMSA, using 3T3-L1 cells nuclear extracts with the −320/−340 region as a probe, demonstrated the binding of C/EBPδ to the element, which was significantly decreased by TNFα treatment. Overexpression of CEBP/δ prevented the TNFα-mediated suppression of PPARγ2 transactivation. Taken together, TNFα suppresses PPARγ2 gene transcription by the inhibition of C/EBPδ expression and its DNA binding during the early stage of adipocyte differentiation, which may contribute to the inhibition of adipocyte differentiation, as well as the induction of insulin resistance.


1998 ◽  
Vol 83 (8) ◽  
pp. 2830-2835 ◽  
Author(s):  
Kyong Soo Park ◽  
Theodore P. Ciaraldi ◽  
Kristin Lindgren ◽  
Leslie Abrams-Carter ◽  
Sunder Mudaliar ◽  
...  

abstract Troglitazone, besides improving insulin action in insulin-resistant subjects, is also a specific ligand for the nuclear receptor peroxisome proliferator-activated receptor-γ (PPARγ). To determine whether troglitazone might enhance insulin action by stimulation of PPARγ gene expression in muscle, total PPARγ messenger RNA (mRNA), and protein were determined in skeletal muscle cultures from nondiabetic control and type II diabetic subjects before and after treatment of cultures with troglitazone (4 days ± troglitazone, 11.5μ m). Troglitazone treatment increased PPARγ mRNA levels up to 3-fold in muscle cultures from type II diabetics (277 ± 63 to 630 ± 100 × 103 copies/μg total RNA, P = 0.003) and in nondiabetic control subjects (200 ± 42 to 490 ± 81, P = 0.003). PPARγ protein levels in both diabetic (4.7 ± 1.6 to 13.6± 3.0 AU/10 μg protein, P &lt; 0.02) and nondiabetic cells (7.4 ± 1.0 to 12.7 ± 1.8, P &lt; 0.05) were also up-regulated by troglitazone treatment. Increased PPARγ was associated with stimulation of human adipocyte lipid binding protein (ALBP) and muscle fatty acid binding protein (mFABP) mRNA, without change in the mRNA for glycerol-3-phosphate dehydrogenase, PPARδ, myogenin, uncoupling protein-2, or sarcomeric α-actin protein. In summary, we showed that troglitazone markedly induces PPARγ, ALBP, and mFABP mRNA abundance in muscle cultures from both nondiabetic and type II diabetic subjects. Increased expression of PPARγ protein and other genes involved in glucose and lipid metabolism in skeletal muscle may account, in part, for the insulin sensitizing effects of troglitazone in type II diabetes.


Endocrinology ◽  
2010 ◽  
Vol 151 (7) ◽  
pp. 3195-3203 ◽  
Author(s):  
Qinqiang Long ◽  
Ting Lei ◽  
Bin Feng ◽  
Changjun Yin ◽  
Dan Jin ◽  
...  

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.


2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Mohd Nor Norazmi ◽  
Rafeezul Mohamed ◽  
Asma Abdullah Nurul ◽  
Nik Soriani Yaacob

Given their roles in immune regulation, the expression of the nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ) 1 and 2 isoforms was investigated in human naïve (CD45RA+) and memory (CD45RO+) CD4+ T cells. Stimulation of both types of cells via the CD3/CD28 pathway resulted in high expression of both PPARγ receptors as measured by real-time PCR. Treatment with the PPARγ agonist, ciglitazone, increased PPARγ1 expression but decreased PPARγ2 expression in stimulated naïve and memory cells. Furthermore, when present, the magnitude of both PPARγ receptors expression was lower in naïve cells, perhaps suggesting a lower regulatory control of these cells. Similar profiles of selected proinflammatory cytokines were expressed by the two cell types following stimulation. The induction of PPARγ1 and suppression of PPARγ2 expressions in naïve and memory CD4+ T cells in the presence of ciglitazone suggest that the PPARγ subtypes may have different roles in the regulation of T-cell function.


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