The transcription factor STAT1 is essential for interferon- (IFN) mediated protective immunity in humans and mice. Two splice isoforms of STAT1, STAT1 and STAT1, differ with regard to a C-terminal transactivation domain, which is absent in STAT1. Dimers of STAT1 are therefore considered transcriptionally inactive and potential competitive inhibitors of STAT1. Contrasting this view, generation and analysis of mice deficient for either STAT1 or STAT1 demonstrated transcriptional activity of the STAT1 isoform and its enhancement of innate immunity. Gene expression profiling in primary cells revealed overlapping, but also non-redundant and gene-specific activities of STAT1 and STAT1 in response to IFN. Consistently, both isoforms mediated protective, IFN-dependent immunity against the bacterium Listeria monocytogenes, although with remarkably different efficiency. In contrast, STAT1 and STAT1 were largely redundant for transcriptional responses to IFN/ and for IFN/-dependent antiviral activity. Collectively, our data shed new light on how STAT1 isoforms contribute to antimicrobial immunity.
STAT1β is not dominant negative and is capable of contributing to gamma interferon-dependent innate immunity.
Specimen part
View SamplesBackground: Peripheral blood mononuclear cells (PBMCs) are relatively easily obtainable cells in humans. Gene expression profiles of PBMCs have been shown to reflect the pathological and physiological state of a person. Recently, we showed that the nuclear receptor peroxisome proliferator-activated receptor alpha (PPAR) has a functional role in human PBMCs during fasting. However, the extent of the role of PPAR in human PBMCs remains unclear. In this study, we therefore performed gene expression profiling of PBMCs incubated with the specific PPAR ligand WY14,643. Results: Incubation of PBMCs with WY14,643 for 12 hours resulted in a differential expression of 1,373 of the 13,080 genes expressed in the PBMCs. Gene expression profiles showed a clear individual response to PPAR activation between six healthy human blood donors, which was not the result of the nutritional status of the donors. Pathway analysis showed that genes in fatty acid metabolism, primarily in -oxidation were up-regulated upon activation of PPAR with WY14,643, and genes in several amino acid metabolism pathways were down-regulated. Conclusions: This study shows that PPAR in human PBMCs regulates fatty acid and amino acid metabolism. In addition, PBMC gene expression profiles show individual responses to WY14,643 activation. We show that PBMCs are a suitable model to study changes in PPAR activation in healthy humans.
Activation of peroxisome proliferator-activated receptor alpha in human peripheral blood mononuclear cells reveals an individual gene expression profile response.
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Detailed transcriptomics analysis of the effect of dietary fatty acids on gene expression in the heart.
Sex, Treatment
View SamplesFatty acids comprise the primary energy source for the heart and are mainly taken up via hydrolysis of circulating triglyceride-rich lipoproteins. While most of the fatty acids entering the cardiomyocyte are oxidized, a small portion is involved in altering gene transcription to modulate cardiometabolic functions. So far, no in vivo model has been developed enabling study of the transcriptional effects of specific fatty acids in the intact heart. In the present study, mice were given a single oral dose of synthetic triglycerides composed of one single fatty acid. Hearts were collected 6h thereafter and used for whole genome gene expression profiling. Experiments were conducted in wild-type and PPAR/ mice to allow exploration of the specific contribution of PPAR. It was found that: 1) linolenic acid (C18:3) had the most pronounced effect on cardiac gene expression. 2) The largest similarity in gene regulation was observed between linoleic acid (C18:2) and C18:3. Large similarity was also observed between the synthetic PPAR agonist Wy14643 and docosahexaenoic acid (C22:6). 3) Many genes were regulated by one particular treatment only. Genes regulated by one particular treatment showed large functional divergence. 4) The majority of genes responding to fatty acid treatment were regulated in a PPAR-dependent manner, emphasizing the importance of PPAR in mediating transcriptional regulation by fatty acids in the heart. 5) Several genes were robustly regulated by all or many of the fatty acids studied, mostly representing well-described targets of PPARs (e.g. Acot1, Angptl4, Ucp3). 6) Deletion and activation of PPAR had a major effect on expression of numerous genes involved in metabolism and immunity. Our analysis demonstrates the marked impact of dietary fatty acids on gene regulation in the heart via PPAR.
Detailed transcriptomics analysis of the effect of dietary fatty acids on gene expression in the heart.
Sex, Treatment
View SamplesStudies in mice have shown that PPAR is an important regulator of hepatic lipid metabolism and the acute phase response. However, little information is available on the role of PPAR in human liver. Here we set out to compare the function of PPAR in mouse and human hepatocytes via analysis of target gene regulation. Primary hepatocytes from 6 human and 6 mouse donors were treated with PPAR agonist Wy14643 and gene expression profiling was performed using Affymetrix GeneChips followed by a systems biology analysis. Baseline PPAR expression was similar in human and mouse hepatocytes. Depending on species and time of exposure, Wy14643 significantly induced the expression of 362-672 genes. Surprisingly minor overlap was observed between the Wy14643-regulated genes from mouse and human, although more substantial overlap was observed at the pathway level. Xenobiotics metabolism and apolipoprotein synthesis were specifically regulated by PPAR in human hepatocytes, whereas glycolysis-gluconeogenesis was regulated specifically in mouse hepatocytes. Most of the genes commonly regulated in mouse and human were involved in lipid metabolism and many represented known PPAR targets, including CPT1A, HMGCS2, FABP, ACSL, and ADFP. Several genes were identified that were specifically induced by PPAR in human (MBL2, ALAS1, CYP1A1, TSKU) or mouse (Fbp2, lgals4, Cd36, Ucp2, Pxmp4). Furthermore, several putative novel PPAR targets were identified that were commonly regulated in both species, including CREB3L3, KLF10, KLF11 and MAP3K8. Our results suggest that PPAR activation has a major impact on gene regulation in human hepatocytes. Importantly, the role of PPAR as master regulator of hepatic lipid metabolism is generally well-conserved between mouse and human. Overall, however, PPAR regulates a mostly divergent set of genes in mouse and human hepatocytes.
Comparative analysis of gene regulation by the transcription factor PPARalpha between mouse and human.
Sex, Age, Specimen part, Subject, Time
View SamplesElevated circulating triglycerides, which are considered a risk factor for cardiovascular disease, can be targeted by treatment with fenofibrate or fish oil. To gain insight into underlying mechanisms, we carried out a comparative transcriptomics and metabolomics analysis of the effect of 2 week treatment withfenofibrate and fish oil in mice. Plasma triglycerides were significantly decreased byfenofibrate (-49.1%) and fish oil (-21.8%), whereas plasma cholesterol was increased by fenofibrate (+29.9%) and decreased by fish oil (-32.8%). Levels of various phospholipid species were specifically decreased by fish oil, while levels of Krebs cycle intermediates were increased specifically by fenofibrate. Plasma levels of many amino acids were altered by fenofibrate and to a lesser extent by fish oil. Both fenofibrate and fish oil upregulated genes involved in fatty acid metabolism, and downregulated genes involved in blood coagulation and fibrinolysis. Significant overlap in gene regulation by fenofibrate and fish oil was observed, reflecting their property as high or low affinity agonist for PPAR, respectively. Fenofibrate specifically downregulated genes involved in complement cascade and inflammatory response. Fish oil specifically downregulated genes involved in cholesterol and fatty acid biosynthesis, and upregulated genes involved in amino acid and arachidonic acid metabolism. Taken together, the data indicate that despite being similarly potent towards modulating plasma free fatty acids, cholesterol and triglyceride levels, fish oil causes modest changes in gene expression likely via activation of multiple mechanistic pathways, whereas fenofibrate causes pronounced gene expression changes via a single pathway, reflecting the key difference between nutritional and pharmacological intervention.
Comparative transcriptomic and metabolomic analysis of fenofibrate and fish oil treatments in mice.
Sex, Age, Specimen part
View SamplesStudies in mice have shown that PPAR is an important regulator of hepatic lipid metabolism and the acute phase response. However, little information is available on the role of PPAR in human liver. Here we set out to compare the function of PPAR in mouse and human hepatocytes via analysis of target gene regulation. Primary hepatocytes from 6 human and 6 mouse donors were treated with PPAR agonist Wy14643 and gene expression profiling was performed using Affymetrix GeneChips followed by a systems biology analysis. Baseline PPAR expression was similar in human and mouse hepatocytes. Depending on species and time of exposure, Wy14643 significantly induced the expression of 362-672 genes. Surprisingly minor overlap was observed between the Wy14643-regulated genes from mouse and human, although more substantial overlap was observed at the pathway level. Xenobiotics metabolism and apolipoprotein synthesis were specifically regulated by PPAR in human hepatocytes, whereas glycolysis-gluconeogenesis was regulated specifically in mouse hepatocytes. Most of the genes commonly regulated in mouse and human were involved in lipid metabolism and many represented known PPAR targets, including CPT1A, HMGCS2, FABP, ACSL, and ADFP. Several genes were identified that were specifically induced by PPAR in human (MBL2, ALAS1, CYP1A1, TSKU) or mouse (Fbp2, lgals4, Cd36, Ucp2, Pxmp4). Furthermore, several putative novel PPAR targets were identified that were commonly regulated in both species, including CREB3L3, KLF10, KLF11 and MAP3K8. Our results suggest that PPAR activation has a major impact on gene regulation in human hepatocytes. Importantly, the role of PPAR as master regulator of hepatic lipid metabolism is generally well-conserved between mouse and human. Overall, however, PPAR regulates a mostly divergent set of genes in mouse and human hepatocytes.
Comparative analysis of gene regulation by the transcription factor PPARalpha between mouse and human.
Sex, Age, Specimen part, Subject, Time
View SamplesStudies in mice have shown that PPAR is an important regulator of hepatic lipid metabolism and the acute phase response. However, little information is available on the role of PPAR in human liver. Here we set out to compare the function of PPAR in mouse and human hepatocytes via analysis of target gene regulation. Primary hepatocytes from 6 human and 6 mouse donors were treated with PPAR agonist Wy14643 and gene expression profiling was performed using Affymetrix GeneChips followed by a systems biology analysis. Baseline PPAR expression was similar in human and mouse hepatocytes. Depending on species and time of exposure, Wy14643 significantly induced the expression of 362-672 genes. Surprisingly minor overlap was observed between the Wy14643-regulated genes from mouse and human, although more substantial overlap was observed at the pathway level. Xenobiotics metabolism and apolipoprotein synthesis were specifically regulated by PPAR in human hepatocytes, whereas glycolysis-gluconeogenesis was regulated specifically in mouse hepatocytes. Most of the genes commonly regulated in mouse and human were involved in lipid metabolism and many represented known PPAR targets, including CPT1A, HMGCS2, FABP, ACSL, and ADFP. Several genes were identified that were specifically induced by PPAR in human (MBL2, ALAS1, CYP1A1, TSKU) or mouse (Fbp2, lgals4, Cd36, Ucp2, Pxmp4). Furthermore, several putative novel PPAR targets were identified that were commonly regulated in both species, including CREB3L3, KLF10, KLF11 and MAP3K8. Our results suggest that PPAR activation has a major impact on gene regulation in human hepatocytes. Importantly, the role of PPAR as master regulator of hepatic lipid metabolism is generally well-conserved between mouse and human. Overall, however, PPAR regulates a mostly divergent set of genes in mouse and human hepatocytes.
Comparative analysis of gene regulation by the transcription factor PPARalpha between mouse and human.
Sex, Age, Specimen part, Time
View SamplesPlant roots perceive neighbouring roots even when resource depletion is low. The transcriptomic response to the presence or absence of an inferior competitor (Hieracium pilosella) is therefore examined in roots of A. thaliana. The experiment was set up in pots filled with non-sterile sand, that allowed to sample roots of eight week old Arabidopsis plants. 3 biological replicates per treatment were examined. Each of these replicates represents 3 pooled samples from individual plants.
Belowground neighbor perception in Arabidopsis thaliana studied by transcriptome analysis: roots of Hieracium pilosella cause biotic stress.
Age, Specimen part
View SamplesLittle is known about the role of the transcription factor PPAR/d in liver. Here we set out to better elucidate the function of PPAR/d in liver by comparing the effect of PPARa and PPAR/d deletion using whole genome transcriptional profiling and analysis of plasma and liver metabolites. In fed state, the number of genes altered by PPARa and PPAR/d deletion was similar, whereas in fasted state the effect of PPARa deletion was much more pronounced, consistent with the pattern of gene expression of PPARa and PPAR/d. Minor overlap was found between PPARa- and PPAR/d-dependent gene regulation in liver. Pathways upregulated by PPAR/d deletion were connected to innate immunity. Pathways downregulated by PPAR/d deletion included lipoprotein metabolism and various pathways related to glucose utilization, which correlated with elevated plasma glucose and triglycerides and reduced plasma cholesterol in PPAR/d-/- mice. Downregulated genes that may underlie these metabolic alterations included Pklr, Fbp1, Apoa4, Vldlr, Lipg, and Pcsk9, which may represent novel PPAR/d target genes. In contrast to PPARa-/- mice, no changes in plasma FFA, plasma -hydroxybutyrate, liver triglycerides and liver glycogen were observed in PPAR/d-/- mice. Our data indicate a role for PPAR/d in hepatic glucose utilization and lipoprotein metabolism but not in the adaptive response to fasting.
Transcriptional profiling reveals divergent roles of PPARalpha and PPARbeta/delta in regulation of gene expression in mouse liver.
Sex, Specimen part
View Samples