Unknown,Transcriptomics,Genomics,Proteomics

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Evaluation of lipin-1 effects on gene expression during TLR4 stimulation of macrophages

ABSTRACT: Lipin-1 affects the expression levels of many genes during TLR4 stimulation of macrophages. Gene expression analysis of peritoneal macrophages from four control (hetorozygotes) mice and four lipin-1 mutant (fatty liver distrophy, fld) mice stimulated with 100 ng/ml LPS for 5 hours.

ORGANISM(S): Mus musculus

SUBMITTER: Maria Balboa

PROVIDER: E-GEOD-54155 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Lipin-1 integrates lipid synthesis with proinflammatory responses during TLR activation in macrophages.

Meana Clara C Peña Lucía L Lordén Gema G Esquinas Esperanza E Guijas Carlos C Valdearcos Martín M Balsinde Jesús J Balboa María A MA

Journal of immunology (Baltimore, Md. : 1950) 20140924 9

Lipin-1 is a Mg(2+)-dependent phosphatidic acid phosphatase involved in the de novo synthesis of phospholipids and triglycerides. Using macrophages from lipin-1-deficient animals and human macrophages deficient in the enzyme, we show in this work that this phosphatase acts as a proinflammatory mediator during TLR signaling and during the development of in vivo inflammatory processes. After TLR4 stimulation lipin-1-deficient macrophages showed a decreased production of diacylglycerol and activati ...[more]

PMID: 25252959

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Project description:Interferon (IFN)γ and interleukin (IL)-4 are central regulators of T helper 1 (Th1) and T helper 2 (Th2) immune responses, respectively. Both cytokines have a major impact on macrophage phenotypes: IFNγ–priming and subsequent TLR4 activation induces so called classically activated macrophages that are characterized by pronounced pro-inflammatory responses, whereas IL-4–treated macrophages, commonly called alternatively activated, are known to develop enhanced capacity for endocytosis, antigen presentation, and tissue repair and are generally considered anti-inflammatory. Considering IL-4 as priming rather than activating stimulus, we now compared the TLR4–dependent global gene activation program in IFNγ– versus IL-4–pretreated mouse macrophages, which has rarely been studied so far. Although both cytokines frequently induced opposing effects on gene transcription, the subsequent activation of bone marrow-derived macrophages by lipopolysaccharide (LPS) produced a strong, priming dependent pro-inflammatory response in both macrophage types. For example, the production of key pro-inflammatory cytokines IL-6 and IL-12 was significantly higher in IL-4– versus IFNγ–primed macrophages and several cytokine genes, including Il19, Ccl17, Ccl22, Ccl24 and Cxcl5, were preferentially induced in alternatively primed and LPS activated mouse macrophages. In a subset of genes, including IL12a, IFNγ priming was actually found to suppress LPS–induced gene expression in a Stat1–dependent manner. Our data suggest that IL-4–priming is not per se anti-inflammatory but generates a macrophage that is “tissue protective” but still capable of mounting a strong inflammatory response after TLR4–dependent activation. Keywords: Gene expression profiling Gene expression was investigated in mouse bone marrow-derived macrophages (BMM). On day 7, BMM were stimulated with either IL-4 or IFNγ overnight (18h in total). LPS treatment was performed in primed and unprimed macrophages 4 h prior to harvesting. At least three independent experiments were performed for each condition.

Project description:Precise control of the innate immune response is required for resistance to microbial infections and maintenance of normal tissue homeostasis. Because this response involves coordinate regulation of hundreds of genes, it provides a powerful biological system to elucidate the molecular strategies that underlie signal- and time-dependent transitions of gene expression. Using a combination of genome-wide and gene-specific approaches, we provide evidence that rather than representing off/on transitions, Toll-like receptor 4 (TLR4)-dependent activation of nearly all immediate/early (I/E) and late response genes results from a sequential process in which signal-independent factors, exemplified by Gabpa, initially establish basal levels of gene expression that are then amplified by signal-dependent transcription factors. Promoters of I/E genes are distinguished from those of late genes by the use of distinct sets of signal-dependent transcription factors, preferential binding of TBP and basal enrichment for RNA Pol II immediately downstream of transcriptional start sites. Global nuclear run-on (GRO) sequencing and total RNA sequencing further indicates that TLR4 signaling markedly increases efficiency of transcriptional elongation of nearly all I/E genes, while RNA splicing is largely unaffected. NCoR/SMRT co-repressor complexes are unexpectedly found to be associated with H3K4me3-positive promoters of TLR4-responsive genes that exhibit a broad range of basal expression levels, implying a dynamic, rather than static role in regulation of gene expression. Collectively, these findings reveal mechanisms underlying temporally distinct patterns of TLR4-dependent gene activation required for homeostasis and effective immune responses. ChIP-Seq, Total RNA-Seq, Gro-Seq, and gene expression profiling was performed in macrophages treated with Kdo2 Lipid A. Control samples for H3K4me3 and Input in Macrophages and B cells, in addition to control microarray data are included in GEO accession# GSE21512

Dataset Information

Evaluation of lipin-1 effects on gene expression during TLR4 stimulation of macrophages

Publications

Lipin-1 integrates lipid synthesis with proinflammatory responses during TLR activation in macrophages.

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