Project description:Fatty 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 PPARalpha-/- mice to allow exploration of the specific contribution of PPARalpha. 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 PPARalpha 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 PPARalpha-dependent manner, emphasizing the importance of PPARalpha 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 PPARalpha 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 PPARalpha. To study the transcriptional effects of specific fatty acids in the intact heart, wild type and PPARalpha-/- mice were given a single oral dose of 4 synthetic triglycerides composed of one single fatty acid, as well as of the synthetic PPARalpha agonist Wy14,643. Hearts were collected 6h after gavag and used for whole genome gene expression profiling.

Project description:This SuperSeries is composed of the following subset Series:; GSE8290: Comprehensive analysis of PPARÎ±-dependent regulation of hepatic lipid metabolism by expression profiling - 1; GSE8291: Comprehensive analysis of PPARÎ±-dependent regulation of hepatic lipid metabolism by expression profiling - 2; GSE8292: Comprehensive analysis of PPARÎ±-dependent regulation of hepatic lipid metabolism by expression profiling - 3; GSE8295: Comprehensive analysis of PPARÎ±-dependent regulation of hepatic lipid metabolism by expression profiling - 4; GSE8302: Comprehensive analysis of PPARÎ±-dependent regulation of hepatic lipid metabolism by expression profiling - 5; PPARalpha is a ligand-activated transcription factor involved in the regulation of nutrient metabolism and inflammation. Although much is already known about the function of PPARalpha in hepatic lipid metabolism, many PPARalpha-dependent pathways and genes have yet to be discovered. In order to obtain an overview of PPARalpha-regulated genes relevant to lipid metabolism, and to probe for novel candidate PPARalpha target genes, livers from several animal studies in which PPARalpha was activated and/or disabled were analyzed by Affymetrix GeneChips. Numerous novel PPARalpha-regulated genes relevant to lipid metabolism were identified. Out of this set of genes, eight genes were singled out for study of PPARalpha-dependent regulation in mouse liver and in mouse, rat, and human primary hepatocytes, including thioredoxin interacting protein (Txnip), electron-transferring-flavoprotein beta polypeptide (Etfb), electron-transferring-flavoprotein dehydrogenase (Etfdh), phosphatidylcholine transfer protein (Pctp), endothelial lipase (EL, Lipg), adipose triglyceride lipase (Pnpla2), hormone-sensitive lipase (HSL, Lipe), and monoglyceride lipase (Mgll). Using an in silico screening approach, one or more PPAR response elements (PPREs) were identified in each of these genes. Regulation of Pnpla2, Lipe, and Mgll, which are involved in triglyceride hydrolysis, was studied under conditions of elevated hepatic lipids. In wild-type mice fed a high fat diet, the decrease in hepatic lipids following treatment with the PPARalpha agonist Wy14643 was paralleled by significant up-regulation of Pnpla2, Lipe, and Mgll, suggesting that induction of triglyceride hydrolysis may contribute to the anti-steatotic role of PPARalpha. Our study illustrates the power of transcriptional profiling to uncover novel PPARalpha-regulated genes and pathways in liver. Experiment Overall Design: Refer to individual Series

Project description:Studies in mice have shown that PPARalpha is an important regulator of hepatic lipid metabolism and the acute phase response. However, little information is available on the role of PPARalpha in human liver. Here we set out to compare the function of PPARalpha in mouse and human hepatocytes via analysis of target gene regulation. Primary hepatocytes from 6 human and 6 mouse donors were treated with PPARalpha agonist Wy14643 and gene expression profiling was performed using Affymetrix GeneChips followed by a systems biology analysis. Baseline PPARalpha 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 PPARalpha 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 PPARalpha targets, including CPT1A, HMGCS2, FABP, ACSL, and ADFP. Several genes were identified that were specifically induced by PPARalpha in human (MBL2, ALAS1, CYP1A1, TSKU) or mouse (Fbp2, lgals4, Cd36, Ucp2, Pxmp4). Furthermore, several putative novel PPARalpha targets were identified that were commonly regulated in both species, including CREB3L3, KLF10, KLF11 and MAP3K8. Our results suggest that PPARalpha activation has a major impact on gene regulation in human hepatocytes. Importantly, the role of PPARalpha as master regulator of hepatic lipid metabolism is generally well-conserved between mouse and human. Overall, however, PPARalpha regulates a mostly divergent set of genes in mouse and human hepatocytes. Experiment Overall Design: Primary hepatocytes from 6 human subjects were treated with the PPARalpha agonist Wy14643 for 6 and 24 hours, and gene expression profiling was performed using Affymetrix GeneChips. Human hepatocytes and Hepatocyte Culture Medium Bulletkit were purchased from Lonza Bioscience (Verviers, Belgium). Primary hepatocytes were isolated from surgical liver biopsies obtained from six individual donors who underwent surgery after informed consent was obtained for surgery with subsequent use of samples in experiments. Hepatocytes were isolated with two-step collagenase perfusion method and the viability of the cells was over 80%. Cells were plated on collagen-coated six-well plates and filled with maintenance medium. Upon arrival of the cells, the medium was discarded and was replaced by Hepatocyte Culture Medium (HCM) with additives. The additives included Gentamicin sulphate/Amphotercin-B, Bovine serum albumin (Fatty acid free), Transferrin, Ascorbic acid, Insulin, Epidermal growth factor, Hydrocortisone hemisuccinate. The next day, cells were incubated in fresh medium in the presence or absence of Wy14643 (50 microM) dissolved in DMSO for 6 and 24 hours, followed by RNA isolation.

Dataset Information

Mus musculus

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure