scholarly journals Adiponectin Secretion Is Regulated by SIRT1 and the Endoplasmic Reticulum Oxidoreductase Ero1-Lα

2007 ◽  
Vol 27 (13) ◽  
pp. 4698-4707 ◽  
Author(s):  
Li Qiang ◽  
Hong Wang ◽  
Stephen R. Farmer
Keyword(s):  
Endoplasmic Reticulum ◽  
Molecular Mechanisms ◽  
Ectopic Expression ◽  
Terminal Phase ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
3T3 Fibroblasts ◽  
Metabolic States ◽  
Interfering Rna ◽  
Circulating Levels

ABSTRACT Adiponectin is secreted from adipose tissue in response to metabolic effectors in order to sensitize the liver and muscle to insulin. Reduced circulating levels of adiponectin that usually accompany obesity contribute to the associated insulin resistance. The molecular mechanisms controlling the production of adiponectin are essentially unknown. In this report, we demonstrate that the endoplasmic reticulum (ER) oxidoreductase Ero1-Lα and effectors modulating peroxisome proliferator-activated receptor γ (PPARγ) and SIRT1 activities regulate secretion of adiponectin from 3T3-L1 adipocytes. Specifically, adiponectin secretion and Ero1-Lα expression are induced during the early phase of adipogenesis but are then down-regulated during the terminal phase, coincident with an increased expression of SIRT1. Suppression of SIRT1 or activation of PPARγ enhances Ero1-Lα expression and stimulates secretion of high-molecular-weight complexes of adiponectin in mature adipocytes. Suppression of Ero1-Lα through expression of a corresponding small interfering RNA reduces adiponectin secretion during the differentiation of 3T3-L1 preadipocytes. Moreover, ectopic expression of Ero1-Lα in Ero1-Lα-deficient 3T3 fibroblasts stimulates the secretion of adiponectin following their conversion into adipocytes and prevents the suppression of adiponectin secretion in response to activation of SIRT1 by exposure to resveratrol. These findings provide a framework to understand the mechanisms by which adipocytes regulate secretion of adiponectin in response to various metabolic states.

scholarly journals Induction of peroxisome proliferator-activated receptor gamma during the conversion of 3T3 fibroblasts into adipocytes is mediated by C/EBPbeta, C/EBPdelta, and glucocorticoids.

1996 ◽  
Vol 16 (8) ◽  
pp. 4128-4136 ◽  
Author(s):  
Z Wu ◽  
N L Bucher ◽  
S R Farmer
Keyword(s):  
Gene Expression ◽  
Expression System ◽  
Ectopic Expression ◽  
Response To Treatment ◽  
Peroxisome Proliferator ◽  
Differentiation Process ◽  
Peroxisome Proliferator Activated Receptor ◽  
Initial Exposure ◽  
3T3 Fibroblasts ◽  
Nih 3T3

The differentiation of 3T3 preadipocytes into adipocytes is accompanied by a transient induction of C/EBPbeta and C/EBPdelta expression in response to treatment of the cells with methylisobutylxanthine (MIX) and dexamethasone (DEX), respectively. In this report, we demonstrate that peroxisome proliferator-activated receptor gamma (PPARgamma) expression in 3T3-L1 preadipocytes is induced by MIX and DEX, suggesting that C/EBPbeta and C/EBPdelta may be involved in this process. Using a tetracycline-responsive expression system, we have recently shown that the conditional ectopic expression of C/EBPbeta in NIH 3T3 fibroblasts (beta2 cells) in the presence of DEX activates the synthesis of peroxisome PPARgamma mRNA. Subsequent exposure of these cells to PPAR activators stimulates their conversion into adipocytes; however, neither the expression of C/EBPbeta nor exposure to DEX alone is capable of inducing PPARgamma expression in the beta2 cell line. We find that unlike the case for 3T3 preadipocytes, C/EBPdelta is not induced by DEX in these 3T3 fibroblasts and therefore is not relaying the effect of this glucocorticoid to the PPARgamma gene. To define the role of glucocorticoids in regulating PPARgamma expression and the possible involvement of C/EBPdelta, we have established an additional set of NIH 3T3 cell lines expressing either C/EBPdelta alone (delta23 cells) or C/EBPdelta and C/EBPbeta together (beta/delta39 cells), using the tetracycline-responsive system. Culture of these cells in tetracycline-deficient medium containing DEX, MIX, insulin, and fetal bovine serum shows that the beta/delta39 cells express PPARgamma and aP2 mRNAs at levels that are almost equivalent to those observed in fully differentiated 3T3-L1 adipocytes. These levels are approximately threefold higher than their levels of expression in the beta2 cells. Despite the fact that these beta/delta39 cells produce abundant amounts of C/EBPbeta and C/EBPdelta (in the absence of tetracycline), they still require glucocorticoids to attain maximum expression of PPARgamma mRNA. Furthermore, the induction of PPARgamma mRNA by exposure of these cells to DEX occurs in the absence of ongoing protein synthesis. The delta23 cells, on the other hand, are not capable of activating PPARgamma gene expression when exposed to the same adipogenic inducers. Finally, attenuation of ectopic C/EBPbeta production at various stages during the differentiation process results in a concomitant inhibition of PPARgamma and the adipogenic program. These data strongly suggest that the induction of PPARgamma gene expression in multipotential mesenchymal stem cells (NIH 3T3 fibroblasts) is dependent on elevated levels of C/EBPbeta throughout the differentiation process, as well as an initial exposure to glucocorticoids. C/EBPdelta may function by synergizing with C/EBPbeta to enhance the level of PPARgamma expression.

scholarly journals Estrogen-related receptor-γ and peroxisome proliferator-activated receptor-γ coactivator-1α regulate estrogen-related receptor-α gene expression via a conserved multi-hormone response element

2005 ◽  
Vol 34 (2) ◽  
pp. 473-487 ◽  
Author(s):  
D Liu ◽  
Z Zhang ◽  
C T Teng
Keyword(s):  
Nuclear Receptors ◽  
Molecular Mechanisms ◽  
Ectopic Expression ◽  
Peroxisome Proliferator ◽  
Hormone Response ◽  
Core Element ◽  
Response Element ◽  
Peroxisome Proliferator Activated Receptor ◽  
Hormone Response Element ◽  
Estrogen Related Receptor

The expression of estrogen-related receptor-α (ERRα) is stimulated by estrogen in selective tissues. Recently, a correlation between ERRα expression and the induction of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) in the liver of fasting animals and in cold-stressed brown-fat tissues and skeletal muscle was shown. To explore the molecular mechanisms of ERRα regulation by diverse signals, the promoter of the human ERRα gene was cloned and characterized. Mutation and deletion analyses revealed that a 53 bp region containing repeated core element AGGTCA motifs of the ERRα gene serves as a multi-hormone response element (MHRE) for several nuclear receptors in transient co-transfection studies of human endometrial carcinoma (HEC-1B) cells. Among the nuclear receptors tested, ERRγ bound to and robustly stimulated the transcription of reporters containing at least two AGGTCA motifs. Ectopic expression of PGC-1α in HEC-1B cells strongly activated the reporter containing the MHRE, presumably via the endogenous nuclear receptor binding to the element. Reducing the endogenous level of ERRγ by small interfering RNA, and increasing the ERRγ level by ectopic expression, substantially decreased and increased respectively the transactivation capability of PGC-1α. The activation function 2 domain of the ERRγ and the L2 and L3 motifs of PGC-1α were essential to transactivate the MHRE. Additionally, PGC-1α increases the amount of endogenous ERRγ bound to the MHRE region as determined by a chromatin immunoprecipitation assay. The present study demonstrates that the MHRE of the ERRα gene is a target for ERRγ transactivation, which is enhanced by PGC-1α.

scholarly journals Peroxisome Proliferator-Activated Receptor γ Activation Restores Islet Function in Diabetic Mice through Reduction of Endoplasmic Reticulum Stress and Maintenance of Euchromatin Structure

2009 ◽  
Vol 29 (8) ◽  
pp. 2053-2067 ◽  
Author(s):  
Carmella Evans-Molina ◽  
Reiesha D. Robbins ◽  
Tatsuyoshi Kono ◽  
Sarah A. Tersey ◽  
George L. Vestermark ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Endoplasmic Reticulum Stress ◽  
Molecular Mechanisms ◽  
Serum Insulin ◽  
Peroxisome Proliferator ◽  
Islet Function ◽  
Direct Role ◽  
Peroxisome Proliferator Activated Receptor ◽  
Ppar Γ

ABSTRACT The nuclear receptor peroxisome proliferator-activated receptor γ (PPAR-γ) is an important target in diabetes therapy, but its direct role, if any, in the restoration of islet function has remained controversial. To identify potential molecular mechanisms of PPAR-γ in the islet, we treated diabetic or glucose-intolerant mice with the PPAR-γ agonist pioglitazone or with a control. Treated mice exhibited significantly improved glycemic control, corresponding to increased serum insulin and enhanced glucose-stimulated insulin release and Ca2+ responses from isolated islets in vitro. This improved islet function was at least partially attributed to significant upregulation of the islet genes Irs1, SERCA, Ins1/2, and Glut2 in treated animals. The restoration of the Ins1/2 and Glut2 genes corresponded to a two- to threefold increase in the euchromatin marker histone H3 dimethyl-Lys4 at their respective promoters and was coincident with increased nuclear occupancy of the islet methyltransferase Set7/9. Analysis of diabetic islets in vitro suggested that these effects resulting from the presence of the PPAR-γ agonist may be secondary to improvements in endoplasmic reticulum stress. Consistent with this possibility, incubation of thapsigargin-treated INS-1 β cells with the PPAR-γ agonist resulted in the reduction of endoplasmic reticulum stress and restoration of Pdx1 protein levels and Set7/9 nuclear occupancy. We conclude that PPAR-γ agonists exert a direct effect in diabetic islets to reduce endoplasmic reticulum stress and enhance Pdx1 levels, leading to favorable alterations of the islet gene chromatin architecture.

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 RT-PCR analysis of corticotroph-associated genes expression in carcinoid tumours in the ectopic-ACTH syndrome

2006 ◽  
Vol 154 (1) ◽  
pp. 159-166 ◽  
Author(s):  
M Messager ◽  
C Carrière ◽  
X Bertagna ◽  
Y de Keyzer
Keyword(s):  
Transcription Factor ◽  
Molecular Mechanisms ◽  
Ectopic Acth Syndrome ◽  
Pcr Analysis ◽  
Peroxisome Proliferator ◽  
Rt Pcr ◽  
Ectopic Acth ◽  
Peroxisome Proliferator Activated Receptor ◽  
Carcinoid Tumours ◽  
Transcription Factor Genes

Objective: ACTH is frequently produced in non-pituitary tumours, leading to the ectopic-ACTH syndrome, but the molecular mechanisms of its expression remain obscure. This study was aimed at understanding the transcription mechanisms of the ACTH-precursor gene in carcinoid tumours of the lung or thymus. Design: Transcripts coding for a series of corticotroph-associated transcription factor genes were detected, together with markers of the corticotroph phenotype. We studied a series of 41 carcinoid tumours including 15 with proven ectopic-ACTH syndrome. Methods: Specific RT-PCR reactions were designed for each gene including alternatively spliced isoforms. Results: The markers of the corticotroph phenotype were detected in all ACTH-positive tumours. Expression of the Tpit and Pitx1 genes were not restricted to ACTH-positive tumours but were also detected in many ACTH-negative carcinoids. Only a subset of ACTH-negative tumours expressed NAK-1/Nur77, and NeuroD1 expression was detected in <50% of the tumours regardless of their secretory status. The glucocorticoid receptor alpha was detected in every tumour in contrast to its beta isoform detectable in a few tumours only. Chicken ovalbumin upstream promoter-transcription factor 1 (COUP-TF1) and peroxisome proliferator-activated receptor (PPAR) γ2 were expressed in 50% of the tumours of each group whereas PPARγ1 was expressed in almost every tumour. Conclusions: ACTH-positive carcinoids do not share a characteristic expression pattern of the corticotroph-associated transcription factor genes, suggesting that the transcriptional mechanisms of the ACTH-precursor gene differ from those in normal pituitary corticotrophs. Expression of Tpit and Pitx1 genes in most carcinoids suggests that some aspects of the pituitary corticotroph phenotype may belong to general carcinoid differentiation.

scholarly journals Growth hormone controls lipolysis by regulation of FSP27 expression

2018 ◽  
Vol 239 (3) ◽  
pp. 289-301 ◽  
Author(s):  
Rita Sharma ◽  
Quyen Luong ◽  
Vishva M Sharma ◽  
Mitchell Harberson ◽  
Brian Harper ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Growth Hormone ◽  
Intracellular Signaling ◽  
Molecular Mechanisms ◽  
Specific Protein ◽  
Negative Regulator ◽  
Gamma Activity ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor

Growth hormone (GH) has long been known to stimulate lipolysis and insulin resistance; however, the molecular mechanisms underlying these effects are unknown. In the present study, we demonstrate that GH acutely induces lipolysis in cultured adipocytes. This effect is secondary to the reduced expression of a negative regulator of lipolysis, fat-specific protein 27 (FSP27; aka Cidec) at both the mRNA and protein levels. These effects are mimicked in vivo as transgenic overexpression of GH leads to a reduction of FSP27 expression. Mechanistically, we show GH modulation of FSP27 expression is mediated through activation of both MEK/ERK- and STAT5-dependent intracellular signaling. These two molecular pathways interact to differentially manipulate peroxisome proliferator-activated receptor gamma activity (PPARγ) on the FSP27 promoter. Furthermore, overexpression of FSP27 is sufficient to fully suppress GH-induced lipolysis and insulin resistance in cultured adipocytes. Taken together, these data decipher a molecular mechanism by which GH acutely regulates lipolysis and insulin resistance in adipocytes.

LncRNA LOC102176306 plays important roles in goat testicular development

Reproduction ◽  
2021 ◽  
Vol 161 (5) ◽  
pp. 523-537
Author(s):  
Shi-Yu An ◽  
Zi-Fei Liu ◽  
El-Samahy M A ◽  
Ming-Tian Deng ◽  
Xiao-Xiao Gao ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Proliferation ◽  
Molecular Mechanisms ◽  
Complex Iii ◽  
Testicular Development ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Atp Production ◽  
Positive Effects ◽  
And Oxidative Stress

Long ncRNAs regulate a complex array of fundamental biological processes, while its molecular regulatory mechanism in Leydig cells (LCs) remains unclear. In the present study, we established the lncRNA LOC102176306/miR-1197-3p/peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PPARGC1A) regulatory network by bioinformatic prediction, and investigated its roles in goat LCs. We found that lncRNA LOC102176306 could efficiently bind to miR-1197-3p and regulate PPARGC1A expression in goat LCs. Downregulation of lncRNA LOC102176306 significantly supressed testosterone (T) synthesis and ATP production, decreased the activities of antioxidant enzymes and mitochondrial complex I and complex III, caused the loss of mitochondrial membrane potential, and inhibited the proliferation of goat LCs by decreasing PPARGC1A expression, while these effects could be restored by miR-1197-3p inhibitor treatment. In addition, miR-1197-3p mimics treatment significantly alleviated the positive effects of lncRNA LOC102176306 overexpression on T and ATP production, antioxidant capacity and proliferation of goat LCs. Taken together, lncRNA LOC102176306 functioned as a sponge for miR-1197-3p to maintain PPARGC1A expression, thereby affecting the steroidogenesis, cell proliferation and oxidative stress of goat LCs. These findings extend our understanding of the molecular mechanisms of T synthesis, cell proliferation and oxidative stress of LCs.

Methanol Extract of Mongolian Iris bungei Maxim. Stimulates 3T3-L1 Adipocyte Differentiation

2021 ◽  
Vol 21 (7) ◽  
pp. 3943-3949
Author(s):  
Jaegoo Yeon ◽  
Sung-Suk Suh ◽  
Ui-Joung Youn ◽  
Badamtsetseg Bazarragchaa ◽  
Ganbold Enebish ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Fatty Acid Synthase ◽  
Molecular Mechanisms ◽  
Adipocyte Differentiation ◽  
Methanol Extract ◽  
Regulatory Element ◽  
Peroxisome Proliferator ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Peroxisome Proliferator Activated Receptor

Iris bungei Maxim. (IB), which is native to China and Mongolia, is used as a traditional medicine for conditions such as inflammation, cancer, and bacterial infections. However, the effects of Iris bungei Maxim. on adipocyte differentiation have not been studied. In the present study, we first demonstrated the molecular mechanisms underlying the adipogenic activity of the methanol extract of Mongolian I. bungei Maxim. (IB). IB significantly enhanced intracellular lipid accumulation and adipocyte differentiation in 3T3-L1 preadipocytes in a concentration-dependent manner. Moreover, IB markedly stimulated the expression of genes related to adipogenesis such as peroxisome proliferator-activated receptor γ, adiponectin, and aP2. In addition, we also observed that IB induces lipogenic genes such as fatty acid synthase, sterol regulatory element binding protein 1c, stearoyl-CoA desaturase, and acetyl-CoA carboxylase. Interestingly IB regulated adipocyte differentiation in both the early and middle stages. Taken together, these adipogenic and lipogenic effects of IB suggest its efficacy for the prevention and/or treatment of type 2 diabetes.

scholarly journals Sijunzi, Lizhong, and Fuzilizhong Decoction Alleviate Nonalcoholic Fatty Liver Disease through Activation of PPAR Pathway

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Jiayao Yang ◽  
Dongqing Tao ◽  
Wei Ma ◽  
Song Liu ◽  
Yan Liao ◽  
...  
Keyword(s):  
Liver Disease ◽  
Fatty Liver ◽  
High Fat Diet ◽  
Fatty Liver Disease ◽  
Molecular Mechanisms ◽  
Peroxisome Proliferator ◽  
High Fat ◽  
Peroxisome Proliferator Activated Receptor ◽  
Nonalcoholic Fatty Liver ◽  
Chinese Herbal

Objective. Sijunzi, Lizhong, and Fuzilizhong decoction were traditional Chinese classic formulations, which are widely used in clinical treatment, and the underlying mechanism is unclear. In this study, we aim to investigate the molecular mechanisms underlying the protective effects of Sijunzi, Lizhong, and Fuzilizhong on nonalcoholic fatty liver disease (NAFLD). Methods. Male Wistar rats were fed a high-fat diet for four weeks to induce NAFLD and were thereafter administered Sijunzi (8 g/kg/d), Lizhong (10 g/kg/d), or Fuzilizhong (10 g/kg/d) by gavage for four weeks. Hepatic damage, lipid accumulation, inflammation, autophagy, and peroxisome proliferator-activated receptor-α signaling were evaluated. Results. The high-fat diet-fed rats showed typical symptoms of NAFLD, including elevated levels of hepatic damage indicators, increased hepatic lipid deposition and fibrosis, severe liver inflammation, and prominent autophagy. Upon administration of Sijunzi, Lizhong, and Fuzilizhong, liver health was improved remarkably, along with ameliorated symptoms of NAFLD. In addition, NAFLD-suppressed peroxisome proliferator-activated receptor-α signaling was reactivated after treatment with the three types of decoctions. Conclusions. The results collectively signify the effective therapeutic and protective functions of Sijunzi, Lizhong, and Fuzilizhong against NAFLD and demonstrate the potential of Chinese herbal medication in mitigating the symptoms of liver diseases. Novelty of the Work. Traditional Chinese herbal medicine has been used for centuries to treat various diseases, but the molecular mechanisms of individual ingredients have rarely been studied. The novelty of our work lies in elucidating the specific signaling pathways involved in the control of NAFLD using three common Chinese herbal decoctions. We suggest that natural herbal formulations can be effective therapeutic agents to combat against NAFLD.

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