THRAP3 depletion reduces PPARγ mRNA and anti-inflammatory action in 3T3-L1 adipocytes

2021 ◽  
Author(s):  
Juu-Chin Lu ◽  
Chia-Yun Lu ◽  
Ying-Yu Wu
Keyword(s):  
Gene Expression ◽  
Thyroid Hormone Receptor ◽  
Peroxisome Proliferator ◽  
Proinflammatory Response ◽  
Peroxisome Proliferator Activated Receptor ◽  
Protein Levels ◽  
Erk Phosphorylation ◽  
Proinflammatory Gene ◽  
Anti Inflammatory ◽  
Proinflammatory Gene Expression

Peroxisome proliferator-activated receptor γ (PPARγ) is the master transcriptional regulator of adipocytes and the cellular target of thiazolidinedione (TZD) drugs. Suppression of proinflammatory actions, including proinflammatory gene expression and lipolysis in adipocytes, contributes to PPARγ-mediated anti-diabetic effects of TZDs. However, adverse side effects largely limited the clinical use of TZDs, despite their potent insulin-sensitizing effects. Therefore, it is important to understand how PPARγ is regulated. Thyroid hormone receptor-associated protein 3 (THRAP3) was previously reported to promote diabetic gene expression by acting as a transcriptional coregulator of PPARγ in adipocytes. Therefore, we tested if THRAP3 modulated anti-inflammatory functions of PPARγ in 3T3-L1 adipocytes. THRAP3 depletion increased basal and tumor necrosis factor α (TNFα)-induced lipolysis, proinflammatory gene expression, and phosphorylation of extracellular signal-regulated kinases (ERKs), suggesting elevated proinflammatory response after THRAP3 depletion in adipocytes. Moreover, TZD-mediated suppression of TNFα-induced lipolysis, proinflammatory gene expression, and ERK phosphorylation were attenuated or alleviated after THRAP3 depletion. Interestingly, the mRNA and protein levels of PPARγ were greatly reduced in THRAP3-depleted adipocytes. Actinomycin D treatment revealed that the stability of PPARγ mRNA was greatly reduced by THRAP3 depletion in adipocytes. Thus, in addition to modulating PPARγ function, THRAP3 may directly regulate the transcript of PPARγ in differentiated adipocytes.

scholarly journals Zygomycetes Hyphae Trigger an Early, Robust Proinflammatory Response in Human Polymorphonuclear Neutrophils through Toll-Like Receptor 2 Induction but Display Relative Resistance to Oxidative Damage

2007 ◽  
Vol 52 (2) ◽  
pp. 722-724 ◽  
Author(s):  
G. Chamilos ◽  
R. E. Lewis ◽  
G. Lamaris ◽  
T. J. Walsh ◽  
D. P. Kontoyiannis
Keyword(s):  
Gene Expression ◽  
Oxidative Damage ◽  
Rhizopus Oryzae ◽  
Polymorphonuclear Neutrophils ◽  
Toll Like Receptor ◽  
Relative Resistance ◽  
Proinflammatory Response ◽  
Proinflammatory Gene ◽  
Toll Like Receptor 2 ◽  
Proinflammatory Gene Expression

ABSTRACT Human polymorphonuclear neutrophils (HPMNs) displayed attenuated hyphal damage associated with impaired O2 − release following exposure to Rhizopus oryzae versus that with Aspergillus fumigatus. Exposure of HPMNs to R. oryzae hyphae resulted in upregulation in Toll-like receptor 2 mRNA and a robust proinflammatory gene expression with rapid (1-h) induction of NF-κB pathway-related genes.

Endotoxin downregulates peroxisome proliferator-activated receptor-γ via the increase in TNF-α release

2008 ◽  
Vol 294 (1) ◽  
pp. R84-R92 ◽  
Author(s):  
Mian Zhou ◽  
Rongqian Wu ◽  
Weifeng Dong ◽  
Asha Jacob ◽  
Ping Wang
Keyword(s):  
Gene Expression ◽  
Neutralizing Antibodies ◽  
Cecal Ligation ◽  
Polymyxin B ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Protein Levels ◽  
Ppar Γ ◽  
Tnf Α ◽  
A Cell

The nuclear receptor peroxisome proliferator-activated receptor-γ (PPAR-γ) is anti-inflammatory in a cell-based system and in animal models of endotoxemia. We have shown that PPAR-γ gene expression is downregulated in macrophages after lipopolysaccharide (LPS) stimulation. However, it remains unknown whether hepatic PPAR-γ is altered in sepsis and, if so, whether LPS directly downregulates PPAR-γ. To study this, rats were subjected to sepsis by cecal ligation and puncture (CLP). Hepatic tissues were harvested at 5, 10, and 20 h after CLP. PPAR-γ gene expression and protein levels were determined by RT-PCR and Western blot analysis, respectively. The results showed that PPAR-γ gene expression decreased at 10 and 20 h and that its proteins levels were reduced at 20 h after CLP. PPAR-γ levels were also decreased in animals that were administered LPS. To determine the direct effects of LPS on PPAR-γ downregulation, LPS binding agent polymyxin B (PMB) was administered intramuscularly after CLP. The administration of PMB significantly reduced plasma levels of endotoxin, but it did not prevent the downregulation of PPAR-γ expression. We found that circulating levels of TNF-α still remained significantly elevated in PMB-treated septic animals. We, therefore, hypothesize that the decrease of PPAR-γ expression is TNF-α dependent. To investigate this, Kupffer cells (KCs) were isolated from normal rats and stimulated with LPS or TNF-α. TNF-α significantly attenuated PPAR-γ gene expression in KCs. Although LPS decreased PPAR-γ in KCs, the downregulatory effect of LPS was blocked by the addition of TNF-α-neutralizing antibodies. Furthermore, the administration of TNF-α-neutralizing antibodies to animals before the onset of sepsis prevented the downregulation of PPAR-γ in sepsis. We, therefore, conclude that LPS downregulates PPAR-γ expression during sepsis via an increase in TNF-α release.

scholarly journals Transcription Suppression of Peroxisome Proliferator-Activated Receptor γ2 Gene Expression by Tumor Necrosis Factor α via an Inhibition of CCAAT/ Enhancer-binding Protein δ during the Early Stage of Adipocyte Differentiation

Endocrinology ◽  
2004 ◽  
Vol 145 (11) ◽  
pp. 4948-4956 ◽  
Author(s):  
Masataka Kudo ◽  
Akira Sugawara ◽  
Akira Uruno ◽  
Kazuhisa Takeuchi ◽  
Sadayoshi Ito
Keyword(s):  
Gene Expression ◽  
Insulin Resistance ◽  
Gene Transcription ◽  
Adipocyte Differentiation ◽  
Early Stage ◽  
Binding Protein ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Protein Levels ◽  
Enhancer Binding Protein

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.

scholarly journals Adipogenesis is differentially impaired by thyroid hormone receptor mutant isoforms

2010 ◽  
Vol 44 (4) ◽  
pp. 247-255 ◽  
Author(s):  
Alok Mishra ◽  
Xu-guang Zhu ◽  
Kai Ge ◽  
Sheue-Yann Cheng
Keyword(s):  
Thyroid Hormone ◽  
Hormone Receptors ◽  
Target Genes ◽  
Thyroid Hormone Receptor ◽  
Fold Increase ◽  
Dominant Negative ◽  
Peroxisome Proliferator ◽  
Loss Of Function ◽  
Peroxisome Proliferator Activated Receptor ◽  
Protein Levels

To understand the roles of thyroid hormone receptors (TRs) in adipogenesis, we adopted a loss-of-function approach. We generated 3T3-L1 cells stably expressing either TRα1 mutant (TRα1PV) or TRβ1 mutant (TRβ1PV). TRα1PV and TRβ1PV are dominant negative mutations with a frameshift in the C-terminal amino acids. In control cells, the thyroid hormone, tri-iodothyronine (T3), induced a 2.5-fold increase in adipogenesis in 3T3-L1 cells, as demonstrated by increased lipid droplets. This increase was mediated by T3-induced expression of the peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα), which are master regulators of adipogenesis at both the mRNA and protein levels. In 3T3-L1 cells stably expressing TRα1PV (L1-α1PV cells) or TRβ1PV (L1-β1PV cells), adipogenesis was reduced 94 or 54% respectively, indicative of differential inhibitory activity of mutant TR isoforms. Concordantly, the expression of PPARγ and C/EBPα at the mRNA and protein levels was more repressed in L1-α1PV cells than in L1-β1PV cells. In addition, the expression of PPARγ downstream target genes involved in fatty acid synthesis – the lipoprotein lipase (Lpl) and aP2 involved in adipogenesis – was more inhibited by TRα1PV than by TRβ1PV. Chromatin immunoprecipitation assays showed that TRα1PV was more avidly recruited than TRβ1PV to the promoter to preferentially block the expression of the C/ebpα gene. Taken together, these data indicate that impaired adipogenesis by mutant TR is isoform dependent. The finding that induction of adipogenesis is differentially regulated by TR isoforms suggests that TR isoform-specific ligands could be designed for therapeutic intervention for lipid abnormalities.

scholarly journals Impaired Adipogenesis Caused by a Mutated Thyroid Hormone α1 Receptor

2007 ◽  
Vol 27 (6) ◽  
pp. 2359-2371 ◽  
Author(s):  
Hao Ying ◽  
Osamu Araki ◽  
Fumihiko Furuya ◽  
Yasuhito Kato ◽  
Sheue-Yann Cheng
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Hormone Receptor ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Protein Levels ◽  
Reduced Body ◽  
X Receptors

ABSTRACT Thyroid hormone (T3) is critical for growth, differentiation, and maintenance of metabolic homeostasis. Mice with a knock-in mutation in the thyroid hormone receptor α gene (TRα1PV) were created previously to explore the roles of mutated TRα1 in vivo. TRα1PV is a dominant negative mutant with a frameshift mutation in the carboxyl-terminal 14 amino acids that results in the loss of T3 binding and transcription capacity. Homozygous knock-in TRα1PV/PV mice are embryonic lethal, and heterozygous TRα1PV/+ mice display the striking phenotype of dwarfism. These mutant mice provide a valuable tool for identifying the defects that contribute to dwarfism. Here we show that white adipose tissue (WAT) mass was markedly reduced in TRα1PV/+ mice. The expression of peroxisome proliferator-activated receptor γ (PPARγ), the key regulator of adipogenesis, was repressed at both mRNA and protein levels in WAT of TRα1PV/+ mice. Moreover, TRα1PV acted to inhibit the transcription activity of PPARγ by competition with PPARγ for binding to PPARγ response elements and for heterodimerization with the retinoid X receptors. The expression of TRα1PV blocked the T3-dependent adipogenesis of 3T3-L1 cells and repressed the expression of PPARγ. Thus, mutations of TRα1 severely affect adipogenesis via cross talk with PPARγ signaling. The present study suggests that defects in adipogenesis could contribute to the phenotypic manifestation of reduced body weight in TRα1PV/+ mice.

scholarly journals CITED2 Restrains Proinflammatory Macrophage Activation and Response

2017 ◽  
Vol 38 (5) ◽  
Author(s):  
Gun-Dong Kim ◽  
Riku Das ◽  
Xiaoquan Rao ◽  
Jixin Zhong ◽  
Jeffrey A. Deiuliis ◽  
...  
Keyword(s):  
Gene Expression ◽  
Target Gene ◽  
Hypoxia Inducible Factor ◽  
Myeloid Cell ◽  
Negative Regulator ◽  
Peroxisome Proliferator ◽  
Gene Promoters ◽  
Loss Of Function ◽  
Peroxisome Proliferator Activated Receptor ◽  
Anti Inflammatory

ABSTRACT Macrophages are strategically distributed in mammalian tissues and play an essential role in priming the immune response. However, macrophages need to constantly strike a balance between activation and inhibition states to avoid a futile inflammatory reaction. Here, we identify the CBP/p300-interacting transactivator with glutamic acid/aspartic acid-rich carboxyl-terminal domain 2 (CITED2) as a potent repressor of macrophage proinflammatory activation. Gain- and loss-of-function studies revealed that CITED2 is required for optimal peroxisome proliferator-activated receptor gamma (PPARγ) activation and attendant select anti-inflammatory gene expression in macrophages. More importantly, deficiency of CITED2 resulted in significant attenuation of rosiglitazone-induced PPARγ activity, PPARγ recruitment to target gene promoters, and anti-inflammatory target gene expression in macrophages. Interestingly, deficiency of Cited2 strikingly heightened proinflammatory gene expression through stabilization of hypoxia-inducible factor 1 alpha (HIF1α) protein in macrophages. Further, overexpression of Egln3 or inhibition of HIF1α in Cited2 -deficient macrophages completely reversed elevated proinflammatory cytokine/chemokine gene expression. Importantly, mice bearing a myeloid cell-specific deletion of Cited2 were highly susceptible to endotoxin-induced sepsis symptomatology and mortality. Collectively, our observations identify CITED2 as a novel negative regulator of macrophage proinflammatory activation that protects the host from inflammatory insults.

scholarly journals Noradrenaline represses PPAR (peroxisome-proliferator-activated receptor) γ2 gene expression in brown adipocytes: intracellular signalling and effects on PPARγ2 and PPARγ1 protein levels

2004 ◽  
Vol 382 (2) ◽  
pp. 597-606 ◽  
Author(s):  
Eva M. LINDGREN ◽  
Ronni NIELSEN ◽  
Natasa PETROVIC ◽  
Anders JACOBSSON ◽  
Susanne MANDRUP ◽  
...  
Keyword(s):  
Gene Expression ◽  
Protein Kinase ◽  
Peroxisome Proliferator ◽  
Mrna Levels ◽  
Down Regulation ◽  
Brown Adipocytes ◽  
Peroxisome Proliferator Activated Receptor ◽  
Protein Levels ◽  
Pparγ Gene ◽  
Kinase A

PPAR (peroxisome-proliferator-activated receptor) γ is expressed in brown and white adipose tissues and is involved in the control of differentiation and proliferation. Noradrenaline stimulates brown pre-adipocyte proliferation and brown adipocyte differentiation. The aim of the present study was thus to investigate the influence of noradrenaline on PPARγ gene expression in brown adipocytes. In primary cultures of brown adipocytes, PPARγ2 mRNA levels were 20-fold higher than PPARγ1 mRNA levels. PPARγ expression occurred during both the proliferation and the differentiation phases, with the highest mRNA levels being found at the time of transition between the phases. PPARγ2 mRNA levels were downregulated by noradrenaline treatment (EC50, 0.1 μM) in both proliferative and differentiating cells, with a lagtime of 1 h and lasting up to 4 h, after which expression gradually recovered. The down-regulation was β-adrenoceptor-induced and intracellularly mediated via cAMP and protein kinase A; the signalling pathway did not involve phosphoinositide 3-kinase, Src, p38 mitogen-activated protein kinase or extracellular-signal-regulated kinases 1 and 2. Treatment of the cells with the protein synthesis inhibitor cycloheximide not only abolished the noradrenaline-induced down-regulation of PPARγ2 mRNA, but also in itself induced PPARγ2 hyperexpression. The down-regulation was probably the result of suppression of transcription. The down-regulation of PPARγ2 mRNA resulted in similar down-regulation of PPARγ2 and phosphoPPARγ2 protein levels. Remarkably, the level of PPARγ1 protein was similar to that of PPARγ2 (despite almost no PPARγ1 mRNA), and the down-regulation by noradrenaline demonstrated similar kinetics to that of PPARγ2; thus PPARγ1 was apparently translated from the PPARγ2 template. It is suggested that β-adrenergic stimulation via cAMP and protein kinase A represses PPARγ gene expression, leading to reduction of PPARγ2 mRNA levels, which is then reflected in down-regulated levels of PPARγ2, phosphoPPARγ2 and PPARγ1.

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