Project description:TNFα is a potent cytokine to mediate inflammatory response by activation of the master transcription factor NF-kB. Endothelial cells are important participants in inflammatory responses in animals. NF-kB is a major mediator to activate endothelial cells by inducing multiple pro-inflammatory genes in response to TNFα. The process of transcriptional activation is dependent on the context of chromatin interactions/loops. However, the chromatin conformation in response to the cytokine challenge TNFα in human aortic endothelial cells has not been described. Our approach characterized chromatin interactions from active enhancers to promoters as well as active promoters to promoters on a genome-wide scale and highlighted important enhancer candidates for target genes.
Project description:The transcription factor IRF4 is crucial for the fate determination of pro-inflammatory T helper (Th)17 and the functionally opposing group of immunomodulatory regulatory T (Treg) cells. However, molecular mechanisms of how IRF4 steers diverse transcriptional programs in Th17 and Treg cells are far from being definitive. To unveil IRF4-driven lineage determination, we integrated data derived from affinity-purification and full mass spectrometry-based proteome analysis with chromatin immune precipitation sequencing. This allowed the characterization of subtype-specific molecular programs and the identification of IRF4 interactors in the Th17/Treg context. Our data reveal that IRF4-interacting transcription factors are recruited to IRF composite elements for the regulation of cell type-specific transcriptional programs as exemplarily demonstrated for FLI1, which in cooperation with IRF4 promotes Th17-specific gene expression. Inhibition of FLI1 markedly impaired Th17-differentiation. The present ‘omics’ dataset provides a valuable resource for studying IRF4-mediated gene regulatory programs in pro- and anti-inflammatory immune responses.
Project description:While much progress has been made in identifying the mechanisms that trigger endothelial activation and inflammatory cell recruitment during atherosclerosis, less is known about the intrinsic pathways that counteract these events. Here we identified NOTCH1 as an antagonist of endothelial cell activation. NOTCH1 was constitutively expressed by adult arterial endothelium, but levels were significantly reduced by high fat diet. Furthermore, treatment of human aortic endothelial cells (HAEC) with inflammatory lipids (Ox-PAPC) and pro-inflammatory cytokines (TNFalpha and IL1beta) decreased Notch1 expression and signaling in vitro through a mechanism that requires STAT3 activation. Reduction of NOTCH1 in HAEC by siRNA, in the absence of inflammatory lipids or cytokines, increased inflammatory molecules and binding of monocytes. Conversely, some of the effects mediated by Ox-PAPC were reversed by increased NOTCH1 signaling; suggesting a link between lipid-mediated inflammation and Notch1. Interestingly, reduction of NOTCH1 by Ox-PAPC in HAEC was associated with a genetic variant previously correlated to HDL in a human GWAS. Finally endothelial Notch1 heterozygous mice showed higher diet-induced atherosclerosis. Based on these findings, we propose that reduction of endothelial NOTCH1 is a predisposing factor in the onset of vascular inflammation and initiation of atherosclerosis. Transcript profile from Human Aortic Endothelial Cells (HAEC) transfected with siRNA targeting NOTCH1 (n=3) or treated with Ox-PAPC (Oxidized 1-Palmitoyl-2-Arachidonoyl-sn-glycero-3-PhosphoCholine) for 6 hours (n=3) were compared to control HAEC (transfected with control siRNA and control media; n=3).
Project description:Oxidized phospoholipids are a pro-inflammatory component of minimally modified lipoproteins that get trapped in the subendothelial space of atherosclerotic plaques of large arteries. To model the response of endothelial cells in a pro-atherosclerotic enviroment we measured the expression in primary endothelial cells with and without treatment with oxidized phsopolipids from 96 genetically identical donors of anonymous origin. These samples are an extention of samples of similar origin deposited in GSE20060 Primary human aortic endothelial cells were collected from aortic heart explants of heart transplant donors and cultured in standard cell culture condiditions. At confluence, cells were treated with or without 40 ug/ml oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphatidylcholine (Ox-PAPC) for 4 hours in media 199 containing 1% fetal bovine serum. After 4 hours, the cells were collected for RNA extraction and quantification of transcripts via microarrays. Application of electronic probe mask (HT_U133Amsk.cdf) on raw data.
Project description:TNFα is a potent cytokine to mediate inflammatory response by activation of the master transcription factor NF-kB. Endothelial cells are important participants in inflammatory responses in animals. NF-kB is a major mediator to activate endothelial cells by inducing multiple pro-inflammatory genes in response to TNFα. NF-kB mediated gene transcription is known to accompany rapid changes in epigenetic states. However, the epigenetic landscape in response to the cytokine challenge TNFα in mouse endothelial cells has not been described. Our approach characterized the epigenetic profiles on a genome-wide scale and mapped putative active enhancers in primary mouse aortic endothelial cells.
Project description:In this study, we investigated the molecular and functional properties of genetically modified porcine aortic endothelial cells (PAECs) that carry a knockout of α1,3-galactosyltransferase and express human CD46 and thrombomodulin (3GM) in xenogeneic (Normal Human Serum alone) and inflammatory environments (TNF + Normal Human Serum), with Wild Type pig aortic endothelial cells as comparison.