Project description:Lipopolysaccharide (LPS), a Toll-like receptor (TLR) 4 ligand, activates intracellular signaling via adaptors, MyD88 and TRIF, leading to the expression of various genes including proinflammatory cytokines. We used microarrays to examine influence of MyD88 or TRIF deficiency in LPS-inducible gene expression. Experiment Overall Design: Peritoneal macrophages from wild-type, MyD88-/- and TRIF-/- mice were stimulated with LPS for 0, 1 and 4 hours, followed by RNA extraction. Then hybridization on affymetrix microarrays was performed.
Project description:MyD88-independent signal transduction associated with Toll-like receptors (TLRs) 3 and TLR4 is mediated through the adapter protein TRIF (TIR-domain-containing adapter-inducing interferon-beta). It has been proposed that TLR signalling is important for the transcription of crucial inflammasome components like NLRP3, a process that has been termed "priming". In order to test whether TRIF signalling was required for the priming of inflammasome components, we performed a genome wide transcriptional analysis on wild-type and Trif-knockout bone marrow derived macrophages (BMMs) before and 1, 3 and 6 hours after phagocytosis of E. coli. These results indicated that TRIF was involved in the activation and not transcriptional priming of the NLRP3 inflammasome. Bone marrow derived macrophages from WT and Trif knockout mice, stimulated with E.coli for up to 6hrs.
Project description:Pre-stimulation of MDMs with LPS (signals via MyD88 and TRIF dependent pathways) and PolyI:C (signals via a TRIF dependent pathway) leads to a reduced viral infection. In contrast, pre-stimulation with P3C (signals via MyD88 dependent pathway) does not lead to a reduced viral infection. This microarray was performed to find genes that are specifically upregulated in LPS and PolyI:C stimulated MDMs but not P3C stimulated MDMs. So to give us leads into the mechanism involved in the reduction of viral infection. MDMs of four different donors were stimulated for 4h with mock, LPS, PolyI:C or P3C. RNA was isolated and gene expression of these cells was assessed. Gene expression of LPS, PolyI:C and P3C stimulated MDMs was compared to mock.
Project description:Pre-stimulation of MDMs with LPS (signals via MyD88 and TRIF dependent pathways) and PolyI:C (signals via a TRIF dependent pathway) leads to a reduced viral infection. In contrast, pre-stimulation with P3C (signals via MyD88 dependent pathway) does not lead to a reduced viral infection. This microarray was performed to find genes that are specifically upregulated in LPS and PolyI:C stimulated MDMs but not P3C stimulated MDMs. So to give us leads into the mechanism involved in the reduction of viral infection.
Project description:Microarray analysis of Myd88-/-Trif-/- and Myd88-/-Rip2-/- macrophage responses to WT or dotA mutant L. pneumophila. Experiment Overall Design: Bone marrow-derived macrophages from Myd88-/-Trif-/- and Myd88-/-Rip2-/- mice were infected with WT L. pneumophila (Lp02) or dotA mutant L. pneumophila (Lp03) for 4 hours. The RNA was extracted, processed, and hybridized onto Affymetrix 430 2.0 microarrays
Project description:Lipopolysaccharide (LPS), a Toll-like receptor (TLR) 4 ligand, activates intracellular signaling via adaptors, MyD88 and TRIF, leading to the expression of various genes including proinflammatory cytokines. We used microarrays to examine influence of MyD88 or TRIF deficiency in LPS-inducible gene expression. Keywords: Time course after LPS (100 ng/ml) stimulation
Project description:Background: Toll-like family of receptors recognizes pathogen-associated molecular patterns (PAMPs) from different organisms. TLR4 is the receptor for bacterial lipopolysaccharide (LPS), dsRNA viral mimic poly(I:C) binds to TLR3, and bacterial CpG DNA signals through TLR9. TLR4 signaling is mediated by adaptor molecules Myd88 and TRIF while TLR3 pathway involves only the TRIF adaptor and TLR9 signals solely through Myd88. Methods: To identify genes other than those in TLR pathways that mediate macrophage response to different PAMPs, RAW264.7 cells were stimulated with LPS, poly(I:C), or CpG DNA, and RNA was profiled on microarrays 6 hrs and 24 hrs post-treatment. Gene expression data were analyzed to determine genes, pathways and transcriptional networks that are in common and unique to each of the three TLR stimuli. Potentially novel candidates revealed by this analysis were tested for their role in innate immunity using RNA interference. Results: Many genes are differentially regulated by LPS and poly(I:C) at both 6 hrs and 24 hrs following treatment, while CpG DNA elicits a much less pronounced transcriptional response. By analyzing gene expression data for networks and pathways, we prioritized differentially expressed genes that are in common to all three PAMPs as well as those shared by LPS and poly(I:C). Knockdown by RNA interference of two genes, Plec1 and TPST1, inhibited production of IL-6 in response to LPS in cultured macrophages. Conclusions: We have identified novel innate immunity genes that may be important in macrophage response to LPS, poly(I:C), and CpG DNA stimuli. Our results provide potential biomarkers and therapeutic targets that should be further investigated in mice and human populations. Keywords: time course For each treatment (Sigma LPS, LIST LPS, and media only), three biological replicates (separate macrophage cultures and RNA isolations) were profiled. Each sample was labeled with Cy3 and Cy5 and co-hybridized with Stratagene Universal Mouse Reference (dye flip techical replicates). Expression at 2 timepoints (6 and 24 hours post-treatment) was assessed.
Project description:Toll-like receptor 4 (TLR4) plays a pivotal role in the host response to lipopolysaccharide (LPS), a major cell wall component of Gram-negative bacteria. Here we elucidated whether the endocytic adaptor protein Disabled-2 (Dab2) that is abundantly expressed in the macrophages plays a role in LPS-stimulated TLR4 signaling and trafficking. Molecular analysis and transcriptome profiling of the RAW264.7 macrophage-like cells expressing short-hairpin RNA of Dab2 revealed that Dab2 mainly regulated LPS-stimulated TRIF-dependent, but not MyD88-dependent TLR4 signaling. Consequently, knockdown of Dab2 augmented TRIF-dependent interferon regulatory factor 3 activation and the expression for the subsets of inflammatory cytokines and interferon-inducible genes. We further delineated that Dab2 acted as a “clathrin sponge” and sequestered clathrin from TLR4/MD2 complex in the resting stage of macrophages. Clathrin was released from Dab2 and associated with TLR4 to facilitate the internalization of TLR4/MD2 complex together with the bound ligand from the cell surface upon LPS stimulation. Dab2 thereby functions as a negative immune regulator of TLR4 endocytosis and signaling, supporting a novel role of Dab2-associated regulatory circuit in the control of inflammatory response of macrophage to endotoxin.