26 research outputs found
NFE2-Related transcription factor 2 coordinates antioxidant defense with thyroglobulin production and iodination in the thyroid gland
Background: The thyroid gland has a special relationship with oxidative stress. While generation of oxidative substances is part of normal iodide metabolism during thyroid hormone synthesis, the gland must also defend itself against excessive oxidation in order to maintain normal function. Antioxidant and detoxification enzymes aid thyroid cells to maintain homeostasis by ameliorating oxidative insults, including during exposure to excess iodide, but the factors that coordinate their expression with the cellular redox status are not known. The antioxidant response system comprising the ubiquitously expressed NFE2-related transcription factor 2 (Nrf2) and its redox-sensitive cytoplasmic inhibitor Kelch-like ECH-associated protein 1 (Keap1) defends tissues against oxidative stress, thereby protecting against pathologies that relate to DNA, protein, and/or lipid oxidative damage. Thus, it was hypothesized that Nrf2 should also have important roles in maintaining thyroid homeostasis. Methods: Ubiquitous and thyroid-specific male C57BL6J Nrf2 knockout (Nrf2-KO) mice were studied. Plasma and thyroids were harvested for evaluation of thyroid function tests by radioimmunoassays and of gene and protein expression by real-time polymerase chain reaction and immunoblotting, respectively. Nrf2-KO and Keap1-KO clones of the PCCL3 rat thyroid follicular cell line were generated using CRISPR/Cas9 technology and were used for gene and protein expression studies. Software-predicted Nrf2 binding sites on the thyroglobulin enhancer were validated by site-directed in vitro mutagenesis and chromatin immunoprecipitation. Results: The study shows that Nrf2 mediates antioxidant transcriptional responses in thyroid cells and protects the thyroid from oxidation induced by iodide overload. Surprisingly, it was also found that Nrf2 has a dramatic impact on both the basal abundance and the thyrotropin-inducible intrathyroidal abundance of thyroglobulin (Tg), the precursor protein of thyroid hormones. This effect is mediated by cell-autonomous regulation of Tg gene expression by Nrf2 via its direct binding to two evolutionarily conserved antioxidant response elements in an upstream enhancer. Yet, despite upregulating Tg levels, Nrf2 limits Tg iodination both under basal conditions and in response to excess iodide. Conclusions: Nrf2 exerts pleiotropic roles in the thyroid gland to couple cell stress defense mechanisms to iodide metabolism and the thyroid hormone synthesis machinery, both under basal conditions and in response to excess iodide.Fil: Ziros, Panos G. Lausanne University; SuizaFil: Habeos, Ioannis. Patras University; GreciaFil: Chartoumpekis, Dionysios V. University of Pittsburgh; Estados UnidosFil: Ntalampyra, Eleni. Universite de Lausanne; SuizaFil: Somm, Emmanuel. Universite de Lausanne; SuizaFil: Renaud, Cédric O.. Universite de Lausanne; SuizaFil: Bongiovanni, Massimo. Institute Of Pathology Locarno; SuizaFil: Trougakos, Ioannis P. Universidad Nacional y Kapodistríaca de Atenas; GreciaFil: Yamamoto, Masayuki. University Of Tohoku; JapónFil: Kensler, Thomas W.. University of Pittsburgh at Johnstown; Estados UnidosFil: Santisteban, Pilar. Universidad Autónoma de Madrid; EspañaFil: Carrasco, Nancy. University of Yale. School of Medicine; Estados UnidosFil: Ris Stalpers, Carrie. Academic Medical Center; Países BajosFil: Amendola, Elena. Universidad de Nápoles; ItaliaFil: Liao, Xiao-Hui. University of Chicago; Estados UnidosFil: Rossich, Luciano Esteban. Comisión Nacional de Energía Atómica de Argentina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Thomasz, Lisa. Comisión Nacional de Energía Atómica de Argentina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Juvenal, Guillermo Juan. Comisión Nacional de Energía Atómica de Argentina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Refetoff, Samuel. University of Chicago; Estados UnidosFil: Sykiotis, Gerasimos P.. Universite de Lausanne; Suiz
The Transcriptomic Response of the Murine Thyroid Gland to Iodide Overload and the Role of the Nrf2 Antioxidant System
Background: Thyroid follicular cells have physiologically high levels of reactive oxygen species because oxidation of iodide is essential for the iodination of thyroglobulin (Tg) during thyroid hormone synthesis. Thyroid follicles (the functional units of the thyroid) also utilize incompletely understood autoregulatory mechanisms to defend against exposure to excess iodide. To date, no transcriptomic studies have investigated these phenomena in vivo. Nuclear erythroid factor 2 like 2 (Nrf2 or Nfe2l2) is a transcription factor that regulates the expression of numerous antioxidant and other cytoprotective genes. We showed previously that the Nrf2 pathway regulates the antioxidant defense of follicular cells, as well as Tg transcription and Tg iodination. We, thus, hypothesized that Nrf2 might be involved in the transcriptional response to iodide overload. Methods: C57BL6/J wild-type (WT) or Nrf2 knockout (KO) male mice were administered regular water or water supplemented with 0.05% sodium iodide for seven days. RNA from their thyroids was prepared for next-generation RNA sequencing (RNA-Seq). Gene expression changes were assessed and pathway analyses were performed on the sets of differentially expressed genes. Results: Analysis of differentially expressed messenger RNAs (mRNAs) indicated that iodide overload upregulates inflammatory-, immune-, fibrosis- and oxidative stress-related pathways, including the Nrf2 pathway. Nrf2 KO mice showed a more pronounced inflammatory–autoimmune transcriptional response to iodide than WT mice. Compared to previously published datasets, the response patterns observed in WT mice had strong similarities with the patterns typical of Graves’ disease and papillary thyroid carcinoma (PTC). Long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) also responded to iodide overload, with the latter targeting mRNAs that participate mainly in inflammation pathways. Conclusions: Iodide overload induces the Nrf2 cytoprotective response and upregulates inflammatory, immune, and fibrosis pathways similar to autoimmune hyperthyroidism (Graves’ disease) and PTC
Differential Expression of MicroRNAs in Adipose Tissue after Long-Term High-Fat Diet-Induced Obesity in Mice
Obesity is a major health concern worldwide which is associated with increased risk of chronic diseases such as metabolic syndrome, cardiovascular disease and cancer. The elucidation of the molecular mechanisms involved in adipogenesis and obesogenesis is of essential importance as it could lead to the identification of novel biomarkers and therapeutic targets for the development of anti-obesity drugs. MicroRNAs (miRNAs) have been shown to play regulatory roles in several biological processes. They have become a growing research field and consist of promising pharmaceutical targets in various fields such as cancer, metabolism, etc. The present study investigated the possible implication of miRNAs in adipose tissue during the development of obesity using as a model the C57BLJ6 mice fed a high-fat diet
Simvastatin activates Keap1/Nrf2 signaling in rat liver
Some of the statins’ pleiotropic actions have been attributed to their
antioxidant activity. The Nrf2 transcription factor controls the
expression of a number of protective genes in response to oxidative
stress. In the present study, wistar rats, primary hepatocytes as well
as ST2 cells, were employed to explore the potential role of Nrf2 in
mediating the reported antioxidant effects of statins. Simvastatin
triggered nuclear translocation of Nrf2 in rat liver and in primary rat
hepatocytes in a mevalonate-dependent and cholesterol-independent way.
In liver, nuclear extracts from simvastatin-treated rats, the
DNA-binding activity of Nrf2, was significantly increased and the mRNA
of two known targets of Nrf2 (HO-1 and GPX2) was induced. In ST2 cells
stably transfected with constructs bearing Nrf2-binding site
(antioxidant responsive element), simvastatin enhanced Nrf2-mediated
transcriptional activity in a mevalonate-dependent and
cholesterol-independent fashion. In conclusion, activation of Keap1/Nrf2
signaling pathway by simvastatin might provide effective protection of
the cell from the deleterious effects of oxidative stress
Simvastatin lowers reactive oxygen species level by Nrf2 activation via PI3K/Akt pathway
The beneficial effects of HMG-CoA (3-hydroxy-3-methyl-glutaryl-CoA)
reductase inhibitors (statins) have been attributed not only to their
cholesterol lowering effect but also to their pleiotropic actions and
especially to their anti-oxidant activity. Nrf2 (NF-E2-related factor 2)
is a transcription factor that orchestrates the transcriptional response
of cells to oxidative stressors and electrophilic xenobiotics. In this
study, primary mouse embryonic fibroblasts from wild type or Nrf2 knock
out C57B16J mice and ST-2 cells were used to investigate the implication
of Nrf2 in the mediation of the anti-oxidant effects of statins and the
possible involvement of PI3K/Akt pathway in this process. We show for
the first time that simvastatin lowers reactive oxygen species (ROS) by
activating Nrf2 through the PI3K/Akt pathway. (C) 2010 Elsevier Inc. All
rights reserved
Brown Adipose Tissue Responds to Cold and Adrenergic Stimulation by Induction of FGF21
Fibroblast growth factor-21 (FGF21) is a pleiotropic protein involved in
glucose, lipid metabolism and energy homeostasis, with main tissues of
expression being the liver and adipose tissue. Brown adipose tissue
(BAT) is responsible for cold-induced thermogenesis in rodents. The role
of FGF21 in BAT biology has not been investigated. In the present study,
wild-type C57BL/6J mice as well as a brown adipocyte cell line were used
to explore the potential role of cold exposure and beta 3-adrenergic
stimulation in the expression of FGF21 in BAT. Our results demonstrate
that short-term exposure to cold, as well as beta 3-adrenergic
stimulation, causes a significant induction of FGF21 mRNA levels in BAT,
without a concomitant increase in FGF21 plasma levels. This finding
opens new routes for the potential use of pharmaceuticals that could
induce FGF21 and, hence, activate BAT thermogenesis. (C) 2011 The
Feinstein Institute for Medical Research, www.feinsteininstitute.or
Hepatic Gene Expression Profiling in Nrf2 Knockout Mice after Long-Term High-Fat Diet-Induced Obesity
Introduction. The transcription factor NFE2-related factor 2 (Nrf2) is a central regulator of antioxidant and detoxification gene expression in response to electrophilic or oxidative stress. Nrf2 has recently been shown to cross-talk with metabolic pathways, and its gene deletion protected mice from high-fat-diet-(HFD-) induced obesity and insulin resistance. This study aimed to identify potential Nrf2-regulated genes of metabolic interest by comparing gene expression profiles of livers of wild-type (WT) versus Nrf2 knockout (Nrf2-KO) mice after a long-term HFD. Methods. WT and Nrf2-KO mice were fed an HFD for 180 days; total RNA was prepared from liver and used for microarray analysis and quantitative real-time RT-PCR (qRT-PCR). Results. The microarray analysis identified 601 genes that were differentially expressed between WT and Nrf2-KO mice after long-term HFD. Selected genes, including ones known to be involved in metabolic regulation, were prioritized for verification by qRT-PCR: Cyp7a1 and Fabp5 were significantly overexpressed in in contrast, Car, Cyp2b10, Lipocalin 13, Aquaporin 8, Cbr3, Me1, and Nqo1 were significantly underexpressed in Nrf2-KO mice. Conclusion. Transcriptome profiling after HFD-induced obesity confirms that Nrf2 is implicated in liver metabolic gene networks. The specific genes identified here may provide insights into Nrf2-dependent mechanisms of metabolic regulation
Body weights, food consumption and hepatic Fgf21 mRNA levels in 1-month old male mice following the administration of increasing doses of simvastatin for 1 week.
<p><b>A.</b> Body weights of mice before and after exposure to simvastatin expressed as the % of initial weight. *P<0.05 compared with baseline weight. <b>B.</b> Cumulative food intake for the 1-week treatment with simvastatin. *P<0.05 compared with vehicle treatment (0% simvastatin w/w). <b>C.</b> Fgf21 hepatic mRNA levels as assessed by qRT-PCR. *P<0.05 compared with the 0% dose. a, b, c, d, e denote 0%, 0.01%, 0.05%, 0.1% and 0.5% w/w simvastatin in chow, respectively. For panels A, B, C the data are presented as the mean ± SEM. n = 6 per treatment with the exception of the 0.5% dose (n = 3; 5 mice received the treatment and 2 died after the treatment).</p
mRNA levels of Fgf21 in primary hepatocytes and HepG2 cells after overexpression of Srebp-2 or miR-33.
<p>Srebp-2 (<b>A</b>) and Fgf21 (<b>B</b>) mRNA levels in primary hepatocytes after overexpression of Srebp-2. Data are presented as the means ±SEM from 3 individual experiments, each of which included 3 technical replicates. *P<0.05 (compared with empty vector transfection). LDLR (<b>C</b>) and FGF21 (<b>D</b>) mRNA levels in HepG2 cells after overexpression of Srebp-2. Data are presented as the means ±SEM from 6 individual experiments, each of which included 3 technical replicates. *P<0.05 (compared with empty vector transfection). ABCA1 (<b>E</b>) and FGF21 (<b>F</b>) mRNA levels in HepG2 cells after overexpression of miR-33. Data are presented as the means ±SEM from 3 individual experiments, each of which included 3 technical replicates. *P<0.05 (compared with empty vector transfection).</p
Hepatic Gene Expression Profiling in Nrf2 Knockout Mice after Long-Term High-Fat Diet-Induced Obesity
Introduction. The transcription factor NFE2-related factor 2 (Nrf2) is a central regulator of antioxidant and detoxification gene expression in response to electrophilic or oxidative stress. Nrf2 has recently been shown to cross-talk with metabolic pathways, and its gene deletion protected mice from high-fat-diet-(HFD-) induced obesity and insulin resistance. This study aimed to identify potential Nrf2-regulated genes of metabolic interest by comparing gene expression profiles of livers of wild-type (WT) versus Nrf2 knockout (Nrf2-KO) mice after a long-term HFD. Methods. WT and Nrf2-KO mice were fed an HFD for 180 days; total RNA was prepared from liver and used for microarray analysis and quantitative real-time RT-PCR (qRT-PCR). Results. The microarray analysis identified 601 genes that were differentially expressed between WT and Nrf2-KO mice after long-term HFD. Selected genes, including ones known to be involved in metabolic regulation, were prioritized for verification by qRT-PCR: Cyp7a1 and Fabp5 were significantly overexpressed in Nrf2-KO mice; in contrast, Car, Cyp2b10, Lipocalin 13, Aquaporin 8, Cbr3, Me1, and Nqo1 were significantly underexpressed in Nrf2-KO mice. Conclusion. Transcriptome profiling after HFD-induced obesity confirms that Nrf2 is implicated in liver metabolic gene networks. The specific genes identified here may provide insights into Nrf2-dependent mechanisms of metabolic regulation