scholarly journals RNA-bound PGC-1α controls gene expression in liquid-like nuclear condensates

2020 ◽  
Author(s):  
Joaquín Pérez-Schindler ◽  
Bastian Kohl ◽  
Konstantin Schneider-Heieck ◽  
Volkan Adak ◽  
Julien Delezie ◽  
...  
Keyword(s):  
Target Genes ◽  
Rna Binding ◽  
Protein Complexes ◽  
Transcriptional Networks ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Central Function ◽  
Skeletal Muscle Wasting ◽  
Active Transcription ◽  
Transcriptional Coregulator

AbstractThe peroxisome-proliferator-activated receptor-γ coactivator-1α (PGC-1α) integrates environmental cues by controlling complex transcriptional networks in various metabolically active tissues. However, it is unclear how a transcriptional coregulator coordinates dynamic biological programs in response to multifaceted stimuli such as endurance training or fasting. Here, we discovered a central function of the poorly understood C-terminal domain (CTD) of PGC-1α to bind RNAs and assemble multi-protein complexes. Surprisingly, in addition to controlling the coupling of transcription and processing of target genes, RNA binding is indispensable for the recruitment of PGC-1α to chromatin into liquid-like nuclear condensates, which compartmentalize and regulate active transcription. These results demonstrate a hitherto unsuspected molecular mechanism by which complexity in the regulation of large transcriptional networks by PGC-1α is achieved. These findings are not only essential for the basic understanding of transcriptional coregulator-driven control of biological programs, but will also help to devise new strategies to modulate these processes in pathological contexts in which PGC-1α function is dysregulated, such as type 2 diabetes, cardiovascular diseases or skeletal muscle wasting.

scholarly journals RNA-bound PGC-1α controls gene expression in liquid-like nuclear condensates

2021 ◽  
Vol 118 (36) ◽  
pp. e2105951118
Author(s):  
Joaquín Pérez-Schindler ◽  
Bastian Kohl ◽  
Konstantin Schneider-Heieck ◽  
Aurel B. Leuchtmann ◽  
Carlos Henríquez-Olguín ◽  
...  
Keyword(s):  
Transcriptional Control ◽  
Cell Types ◽  
Transcriptional Networks ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Central Function ◽  
Active Liquid ◽  
Active Transcription ◽  
Context Specific ◽  
Liquid Liquid Phase Separation

Plasticity of cells, tissues, and organs is controlled by the coordinated transcription of biological programs. However, the mechanisms orchestrating such context-specific transcriptional networks mediated by the dynamic interplay of transcription factors and coregulators are poorly understood. The peroxisome proliferator–activated receptor γ coactivator 1α (PGC-1α) is a prototypical master regulator of adaptive transcription in various cell types. We now uncovered a central function of the C-terminal domain of PGC-1α to bind RNAs and assemble multiprotein complexes including proteins that control gene transcription and RNA processing. These interactions are important for PGC-1α recruitment to chromatin in transcriptionally active liquid-like nuclear condensates. Notably, such a compartmentalization of active transcription mediated by liquid–liquid phase separation was observed in mouse and human skeletal muscle, revealing a mechanism by which PGC-1α regulates complex transcriptional networks. These findings provide a broad conceptual framework for context-dependent transcriptional control of phenotypic adaptations in metabolically active tissues.

scholarly journals New Target Genes for the Peroxisome Proliferator-Activated Receptor-γ(PPARγ) Antitumour Activity: Perspectives from the Insulin Receptor

PPAR Research ◽  
2009 ◽  
Vol 2009 ◽  
pp. 1-8 ◽  
Author(s):  
Daniela P. Foti ◽  
Francesco Paonessa ◽  
Eusebio Chiefari ◽  
Antonio Brunetti
Keyword(s):  
Insulin Receptor ◽  
Target Genes ◽  
Tumour Progression ◽  
Antitumour Activity ◽  
Peptide Hormone ◽  
Nuclear Hormone Receptor ◽  
Peroxisome Proliferator ◽  
Preclinical Research ◽  
Peroxisome Proliferator Activated Receptor ◽  
Wide Range

The insulin receptor (IR) plays a crucial role in mediating the metabolic and proliferative functions triggered by the peptide hormone insulin. There is considerable evidence that abnormalities in both IR expression and function may account for malignant transformation and tumour progression in some human neoplasias, including breast cancer. PPARγis a ligand-activated, nuclear hormone receptor implicated in many pleiotropic biological functions related to cell survival and proliferation. In the last decade, PPARγagonists—besides their known action and clinical use as insulin sensitizers—have proved to display a wide range of antineoplastic effects in cells and tissues expressing PPARγ, leading to intensive preclinical research in oncology. PPARγand activators affect tumours by different mechanisms, involving cell proliferation and differentiation, apoptosis, antiinflammatory, and antiangiogenic effects. We recently provided evidence that PPARγand agonists inhibit IR by non canonical, DNA-independent mechanisms affecting IR gene transcription. We conclude that IR may be considered a new PPARγ“target” gene, supporting a potential use of PPARγagonists as antiproliferative agents in selected neoplastic tissues that overexpress the IR.

Adipocyte differentiation of 3T3-L1 preadipocytes is dependent on lipoxygenase activity during the initial stages of the differentiation process

2003 ◽  
Vol 375 (3) ◽  
pp. 539-549 ◽  
Author(s):  
Lise MADSEN ◽  
Rasmus K. PETERSEN ◽  
Morten B. SØRENSEN ◽  
Claus JØRGENSEN ◽  
Philip HALLENBORG ◽  
...  
Keyword(s):  
Adipocyte Differentiation ◽  
Critical Evaluation ◽  
Nordihydroguaiaretic Acid ◽  
Whole Body ◽  
Transcriptional Networks ◽  
Peroxisome Proliferator ◽  
The Novel ◽  
Differentiation Process ◽  
Peroxisome Proliferator Activated Receptor ◽  
Brown Adipose

Adipocytes play a central role in whole-body energy homoeostasis. Complex regulatory transcriptional networks control adipogensis, with ligand-dependent activation of PPARγ (peroxisome proliferator-activated receptor γ) being a decisive factor. Yet the identity of endogenous ligands promoting adipocyte differentiation has not been established. Here we present a critical evaluation of the role of LOXs (lipoxygenases) during adipocyte differentiation of 3T3-L1 cells. We show that adipocyte differentiation of 3T3-L1 preadipocytes is inhibited by the general LOX inhibitor NDGA (nordihydroguaiaretic acid) and the 12/15-LOX selective inhibitor baicalein. Baicalein-mediated inhibition of adipocyte differentiation was rescued by administration of rosiglitazone. Treatment with baicalein during the first 4 days of the differentiation process prevented adipocyte differentiation; supplementation with rosiglitazone during the same period was sufficient to rescue adipogenesis. Accordingly, we demonstrate that adipogenic conversion of 3T3-L1 cells requires PPARγ ligands only during the first 4 days of the differentiation process. We show that the baicalein-sensitive synthesis of endogenous PPARγ ligand(s) increases rapidly upon induction of differentiation and reaches a maximum on days 3–4 of the adipocyte differentiation programme. The conventional platelet- and leucocyte-type 12(S)-LOXs and the novel eLOX-3 (epidermis-type LOX-3) are expressed in white and brown adipose tissue, whereas only eLOX-3 is clearly expressed in 3T3-L1 cells. We suggest that endogenous PPARγ ligand(s) promoting adipocyte differentiation are generated via a baicalein-sensitive pathway involving the novel eLOX-3.

Clofibrate causes an upregulation of PPAR-α target genes but does not alter expression of SREBP target genes in liver and adipose tissue of pigs

2007 ◽  
Vol 293 (1) ◽  
pp. R70-R77 ◽  
Author(s):  
Sebastian Luci ◽  
Beatrice Giemsa ◽  
Holger Kluge ◽  
Klaus Eder
Keyword(s):  
Adipose Tissue ◽  
Target Genes ◽  
Regulatory Element ◽  
Control Diet ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Cholesterol Homeostasis ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Hepatic Expression

This study investigated the effect of clofibrate treatment on expression of target genes of peroxisome proliferator-activated receptor (PPAR)-α and various genes of the lipid metabolism in liver and adipose tissue of pigs. An experiment with 18 pigs was performed in which pigs were fed either a control diet or the same diet supplemented with 5 g clofibrate/kg for 28 days. Pigs treated with clofibrate had heavier livers, moderately increased mRNA concentrations of various PPAR-α target genes in liver and adipose tissue, a higher concentration of 3-hydroxybutyrate, and markedly lower concentrations of triglycerides and cholesterol in plasma and lipoproteins than control pigs ( P < 0.05). mRNA concentrations of sterol regulatory element-binding proteins (SREBP)-1 and -2, insulin-induced genes ( Insig) -1 and Insig-2, and the SREBP target genes acetyl-CoA carboxylase, 3-methyl-3-hydroxyglutaryl-CoA reductase, and low-density lipoprotein receptor in liver and adipose tissue and mRNA concentrations of apolipoproteins A-I, A-II, and C-III in the liver were not different between both groups of pigs. In conclusion, this study shows that clofibrate treatment activates PPAR-α in liver and adipose tissue and has a strong hypotriglyceridemic and hypocholesterolemic effect in pigs. The finding that mRNA concentrations of some proteins responsible for the hypolipidemic action of fibrates in humans were not altered suggests that there were certain differences in the mode of action compared with humans. It is also shown that PPAR-α activation by clofibrate does not affect hepatic expression of SREBP target genes involved in synthesis of triglycerides and cholesterol homeostasis in liver and adipose tissue of pigs.

scholarly journals Thioredoxin Binding Protein-2/Thioredoxin-Interacting Protein Is a Critical Regulator of Insulin Secretion and Peroxisome Proliferator-Activated Receptor Function

Endocrinology ◽  
2008 ◽  
Vol 150 (3) ◽  
pp. 1225-1234 ◽  
Author(s):  
Shin-ichi Oka ◽  
Eiji Yoshihara ◽  
Akiko Bizen-Abe ◽  
Wenrui Liu ◽  
Mutsumi Watanabe ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Target Genes ◽  
Binding Protein ◽  
Dynamic Change ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Interacting Protein ◽  
Thioredoxin Interacting Protein ◽  
Nutritional Transition ◽  
Coordinated Regulation

The feeding-fasting nutritional transition triggers a dynamic change in metabolic pathways and is a model for understanding how these pathways are mutually organized. The targeted disruption of the thioredoxin binding protein-2 (TBP-2)/thioredoxin-interacting protein (Txnip)/VDUP1 gene in mice results in lethality with hypertriglyceridemia and hypoglycemia during fasting. To investigate the molecular mechanism of the nutritional transition and the role of TBP-2, microarray analyses were performed using the liver of TBP-2−/− mice in the fed and fasted states. We found that the fasting-induced reduction in the expression of lipogenic genes targeted by insulin (SREBP-1), such as FASN and THRSP, was abolished in TBP-2−/− mice, and the expression of lipoprotein lipase is down-regulated, which was consistent with the lipoprotein profile. TBP-2−/− mice also exhibited enhanced glucose-induced insulin secretion and sensitivity. Another feature of the hepatic gene expression in fed TBP-2−/− mice was the augmented expression of peroxisome proliferator activated receptor (PPAR) target genes, such as CD36, FABP2, ACOT1, and FGF21, to regulate fatty acid consumption. In TBP-2−/− mice, PPARα expression was elevated in the fed state, whereas the fasting-induced up-regulation of PPARα was attenuated. We also detected an increased expression of PPARγ coactivator-1α protein in fed TBP-2−/− mice. TBP-2 overexpression significantly inhibited PPARα-mediated transcriptional activity induced by a specific PPARα ligand in vitro. These results suggest that TBP-2 is a key regulator of PPARα expression and signaling, and coordinated regulation of PPARα and insulin secretion by TBP-2 is crucial in the feeding-fasting nutritional transition. TBP-2/Txnip is a key regulator of PPARα expression and signaling, and coordinated regulation of PPARα and insulin secretion by TBP-2/Txnip is crucial in fasting response.

scholarly journals SIRT3 deficiency exacerbates fatty liver by attenuating the HIF1α-LIPIN 1 pathway and increasing CD36 through Nrf2

2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Emma Barroso ◽  
Rosalía Rodríguez-Rodríguez ◽  
Mohammad Zarei ◽  
Javier Pizarro-Degado ◽  
Anna Planavila ◽  
...  
Keyword(s):  
Hepatic Steatosis ◽  
Target Genes ◽  
Hypoxia Inducible Factor ◽  
Redox Status ◽  
Acid Oxidation ◽  
Standard Diet ◽  
Peroxisome Proliferator ◽  
Lipid Uptake ◽  
Peroxisome Proliferator Activated Receptor ◽  
Vldl Receptor

Abstract Background Deficiency of mitochondrial sirtuin 3 (SIRT3), a NAD+-dependent protein deacetylase that maintains redox status and lipid homeostasis, contributes to hepatic steatosis. In this study, we investigated additional mechanisms that might play a role in aggravating hepatic steatosis in Sirt3-deficient mice fed a high-fat diet (HFD). Methods Studies were conducted in wild-type (WT) and Sirt3−/− mice fed a standard diet or a HFD and in SIRT3-knockdown human Huh-7 hepatoma cells. Results Sirt3−/− mice fed a HFD presented exacerbated hepatic steatosis that was accompanied by decreased expression and DNA-binding activity of peroxisome proliferator-activated receptor (PPAR) α and of several of its target genes involved in fatty acid oxidation, compared to WT mice fed the HFD. Interestingly, Sirt3 deficiency in liver and its knockdown in Huh-7 cells resulted in upregulation of the nuclear levels of LIPIN1, a PPARα co-activator, and of the protein that controls its levels and localization, hypoxia-inducible factor 1α (HIF-1α). These changes were prevented by lipid exposure through a mechanism that might involve a decrease in succinate levels. Finally, Sirt3−/− mice fed the HFD showed increased levels of some proteins involved in lipid uptake, such as CD36 and the VLDL receptor. The upregulation in CD36 was confirmed in Huh-7 cells treated with a SIRT3 inhibitor or transfected with SIRT3 siRNA and incubated with palmitate, an effect that was prevented by the Nrf2 inhibitor ML385. Conclusion These findings demonstrate new mechanisms by which Sirt3 deficiency contributes to hepatic steatosis. Graphical abstract

scholarly journals Branched-Chain Fatty Acids as Mediators of the Activation of Hepatic Peroxisome Proliferator-Activated Receptor Alpha by a Fungal Lipid Extract

Biomolecules ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1259 ◽  
Author(s):  
Garima Maheshwari ◽  
Robert Ringseis ◽  
Gaiping Wen ◽  
Denise K. Gessner ◽  
Johanna Rost ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Reporter Gene ◽  
Target Genes ◽  
Reporter Gene Assay ◽  
Lipid Extract ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Branched Chain Fatty Acids ◽  
Gene Assay ◽  
Branched Chain

The study aimed to test the hypothesis that monomethyl branched-chain fatty acids (BCFAs) and a lipid extract of Conidiobolus heterosporus (CHLE), rich in monomethyl BCFAs, are able to activate the nuclear transcription factor peroxisome proliferator-activated receptor alpha (PPARalpha). Rat Fao cells were incubated with the monomethyl BCFAs 12-methyltridecanoic acid (MTriA), 12-methyltetradecanoic acid (MTA), isopalmitic acid (IPA) and 14-methylhexadecanoic acid (MHD), and the direct activation of PPARalpha was evaluated by reporter gene assay using a PPARalpha responsive reporter gene. Furthermore, Fao cells were incubated with different concentrations of the CHLE and PPARalpha activation was also evaluated by using the reporter gene assay, and by determining the mRNA concentrations of selected PPARalpha target genes by real-time RT-PCR. The reporter gene assay revealed that IPA and the CHLE, but not MTriA, MHD and MTA, activate the PPARalpha responsive reporter gene. CHLE dose-dependently increased mRNA concentrations of the PPARalpha target genes acyl-CoA oxidase (ACOX1), cytochrome P450 4A1 (CYP4A1), carnitine palmitoyltransferase 1A (CPT1A) and solute carrier family 22 (organic cation/carnitine transporter), member 5 (SLC22A5). In conclusion, the monomethyl BCFA IPA is a potent PPARalpha activator. CHLE activates PPARalpha-dependent gene expression in Fao cells, an effect that is possibly mediated by IPA.

scholarly journals Inhibition of HDAC3 promotes ligand-independent PPARγ activation by protein acetylation

2014 ◽  
Vol 53 (2) ◽  
pp. 191-200 ◽  
Author(s):  
Xiaoting Jiang ◽  
Xin Ye ◽  
Wei Guo ◽  
Hongyun Lu ◽  
Zhanguo Gao
Keyword(s):  
Insulin Sensitivity ◽  
Posttranslational Modifications ◽  
Target Genes ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Histone Deacetylase 3 ◽  
Protein Inhibition ◽  
Diet Induced Obesity ◽  
Exogenous Ligands

Peroxisome proliferator-activated receptor gamma (PPARγ) is a nuclear receptor whose activation is dependent on a ligand. PPARγ activation by exogenous ligands, such as thiazolidinediones (TZDs), is a strategy in the treatment of type 2 diabetes mellitus for the improvement of insulin sensitivity. In addition to a ligand, PPARγ function is also regulated by posttranslational modifications, such as phosphorylation, sumoylation, and ubiquitination. Herein, we report that the PPARγ protein is modified by acetylation, which induces the PPARγ function in the absence of an external ligand. We observed that histone deacetylase 3 (HDAC3) interacted with PPARγ to deacetylate the protein. In immunoprecipitation assays, the HDAC3 protein was associated with the PPARγ protein. Inhibition of HDAC3 using RNAi-mediated knockdown or HDAC3 inhibitor increased acetylation of the PPARγ protein. Furthermore, inhibition of HDAC3 enhanced the expression of PPARγ target genes such as adiponectin and aP2. The expression was associated with an increase in glucose uptake and insulin signaling in adipocytes. HDAC3 inhibition enhanced lipid accumulation during differentiation of adipocytes. PPARγ acetylation was also induced by pioglitazone and acetylation was required for PPARγ activation. In the absence of TZDs, the acetylation from HDAC3 inhibition was sufficient to induce the transcriptional activity of PPARγ. Treating diet-induced obesity mice with HDAC3 inhibitor or pioglitazone for 2 weeks significantly improved high-fat-diet-induced insulin resistance. Our results indicate that acetylation of PPARγ is a ligand-independent mechanism of PPARγ activation. HDAC3 inhibitor is a potential PPARγ activator for the improvement of insulin sensitivity.

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