Unknown,Transcriptomics,Genomics,Proteomics

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MiR-155 KO in human dendritic cells

ABSTRACT: In response to inflammatory stimulation, dendritic cells (DCs) have a remarkable pattern of differentiation (maturation) that exhibits specific mechanisms to control immunity. Here, we show that in response to Lipopolysaccharides (LPS), several microRNAs (miRNAs) are regulated in human monocyte-derived dendritic cells. Among these miRNAs, miR-155 is highly up-regulated during maturation. Using LNA silencing combined to microarray technology, we have identified the Toll-like receptor / interleukin-1 (TLR/IL-1) inflammatory pathway as a general target of miR-155. We further demonstrate that miR-155 directly controls the level of important signal transduction molecules. Our observations suggest, therefore, that in mature human DCs, miR-155 is part of a negative feedback loop, which down-modulates inflammatory cytokine production in response to microbial stimuli. We devised a strategy to functionally inhibit the mature form of miR-155 with the aim of identifying the signaling pathways controlled by miR-155 during DC maturation. A LNA-modified oligonucleotide, specifically designed for miR-155 knockdown (anti-miR-155 LNA) was introduced in moDCs by nucleofection prior LPS stimulation. 24h after transfection, a reduction in miR-155 levels of 8- and 32-fold was observed by qPCR in immature and mature moDCs respectively. A comparative microarray analysis (Affymetrix U133 2.0 chip) was performed among miR-155 silenced (anti-miR-155 LNA) and control transfected (scramble LNA) moDCs, exposed or not to LPS. Thus, four samples were totally analyzed. As expected from the limited expression of miR-155 in non-activated DCs, little variation in mRNA expression (177 probe sets differentially expressed employing a cut-off of 1.5) was detected upon miR-155 silencing. Conversely, in LPS-activated cells many mRNAs (1324 probe sets, 770 up-regulated and 554 down-regulated) were affected by miR-155 inhibition.

ORGANISM(S): Homo sapiens

SUBMITTER: Philippe Pierre

PROVIDER: E-GEOD-13296 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

MicroRNA-155 modulates the interleukin-1 signaling pathway in activated human monocyte-derived dendritic cells.

Ceppi Maurizio M Pereira Patricia M PM Dunand-Sauthier Isabelle I Barras Emmanuèle E Reith Walter W Santos Manuel A MA Pierre Philippe P

Proceedings of the National Academy of Sciences of the United States of America 20090204 8

In response to inflammatory stimulation, dendritic cells (DCs) have a remarkable pattern of differentiation (maturation) that exhibits specific mechanisms to control immunity. Here, we show that in response to Lipopolysaccharides (LPS), several microRNAs (miRNAs) are regulated in human monocyte-derived dendritic cells. Among these miRNAs, miR-155 is highly up-regulated during maturation. Using LNA silencing combined to microarray technology, we have identified the Toll-like receptor/interleukin- ...[more]

PMID: 19193853

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Project description:Allergic contact dermatitis (ACD) is the most prevalent form of immunotoxicity in humans. Dendritic cells (DC) play a central role in the pathogenesis of ACD, particularly during the sensitization phase to a specific allergen. Upon activation, DCs maturate and migrate to draining lymph nodes which is accompanied by major metabolic and phenotypic alterations that facilitate the presentation of the captured antigen to prime naïve T cells. Nevertheless, knowledge on the molecular effects during maturation of DCs in the context of ACD remain scarce. Here, we present a global proteomic analysis of monocyte-derived dendritic cells (MoDC) treated with NiSO4, the most prominent cause of ACD. Proteomic alterations induced after treatment with NiSO4 were compared to the bacterial trigger lipopolysaccharide (LPS). Both substances possess a similar TLR4 binding capacity, which may help to identify allergy-specific effects compared to bacterial activation. MoDCs treated for 24 h with 2.5 µg/ ml LPS displayed a very strong immunological response, characterized by upregulation of DC activation markers, secretion of proinflammatory cytokines and stimulation of T cell proliferation. Similar immunological responses were observed after treatment with 400 µM NiSO4 but less pronounced. Both triggered TLR4 and TREM1 pathways. However, NiSO4 in addition, also activated hypoxic and apoptotic pathways, which might have overshadowed initial signaling. Moreover, our proteomic data support the importance of Nrf2 as a key player in mediating sensitization since many Nrf2 targets genes were strongly upregulated on protein level selectively after treatment with NiSO4. Strikingly, NiSO4 stimulation induced cellular hypocholesterolemia which was counteracted by the induction of genes and proteins relevant for cholesterol biosynthesis. Our proteomic study allowed for the first time to better characterize some of the fundamental differences between NiSO4 and LPS-triggered activation of MoDCs, providing an important contribution to the molecular understanding of contact allergy.

Project description:Dendritic cells (DCs) are the sentinels of the mammalian immune system and they undergo a complex maturation process mediated by activation upon pathogen detection. Recent studies described the analysis of activated DCs by transcriptional profiling, but translation regulation was never taken in account. Therefore, the nature of the mRNAs being translated at various stages of DC activation was determined with the help of translational profiling, which is the sucrose gradient fractionation of polysomal-bound mRNAs combined to microarrays analysis. Total and polysomal-bound mRNA populations were compared in immature (0h) and LPS-stimulated (4h and 16h) human monocyte-derived DCs with the help of Affymetrix microarrays. Biostatistical analysis indicated that 296 mRNA molecules are translationally regulated during DC-activation. The most abundant biological process among the regulated mRNAs was protein biosynthesis, indicating the existence of a negative feedback loop regulating translation. Interestingly, a cluster of 17 ribosomal proteins were part of the regulated mRNAs, indicating that translation may be fine-tuned by particular components of the translational machinery. Our observations highlight the importance of translation regulation during the immune response, and may favour the identification of novel gene clusters or protein networks relevant for immunity. Our study also provides information on the possible absence of correlation between gene expression and real protein production in DCs. To identify translationally regulated mRNA molecules, gene expression derived from the polysome-bound mRNAs was compared by Affymetrix microarrays analysis to the gene expression derived from unfractionated total mRNAs derived from whole-cell lysates, as recently described on several reports (Johannes 1999, Rajasekhar 2003, Bushell 2006, Lü 2006, Parent 2008). Polysomal RNA (P) and total RNA (T) were isolated from MoDCs generated from four different blood donors. Since three timepoints (0h, 4h and 16h) were chosen for each blood donor and RNA type, twenty-four RNA samples were totally analyzed by microarrays.

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Dataset Information

MiR-155 KO in human dendritic cells

Publications

MicroRNA-155 modulates the interleukin-1 signaling pathway in activated human monocyte-derived dendritic cells.

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