Project description:We used microarrays to detail the global program of gene expression induced in LPS/IFNgamma stimulated macrophages that were deficient in BH4/Gch1 (GCHfl/flTie2cre vs. GCHfl/fl) over a 24 hour timecourse.
Project description:Inducible nitric oxide synthase (iNOS) plays a crucial role in controlling growth of mycobacteria, presumed to be via nitric oxide (NO) mediated killing. However, NOS enzymes can also signal through NO-independent pathways, and production of NO by NOS requires the cofactor tetrahydrobiopterin (BH4). We compared Nos2-/- mice to mice with macrophage BH4 deficiency (Gch1fl/flTie2cre), due to a leukocyte-specific deletion of Gch1, to uncover the specific contribution of NO-independent NOS functions to anti-mycobacterial immunity. We used microarrays to detail the global programme of gene expression in uninfected and BCG infected macrophages that were either deficient in iNOS (Nos2-/- vs C57bl6/J) or BH4/Gch1 (GCHfl/flTie2cre vs GCHfl/fl)
Project description:Molecular Pathways and Transcriptional Networks Involved in the Macrophage Response to LPS, poly(I:C) and CpG DNA Stimulation 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. For each treatment (LPS, polyIC, CpG DNA, 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:Molecular Pathways and Transcriptional Networks Involved in the Macrophage Response to LPS, poly(I:C) and CpG DNA Stimulation 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.
Project description:To investigate the plasticity of Lipolysaccharide (LPS) tolerance, we employed microarray profiling to analyse the gene expression profile in macrophage. Four macrophage populations were induced; Untreated macrophages (Control group), Acute response to LPS (LPS activation group), LPS tolerance (T – Tolerant group) and recovered (R = recovered macrophage group) Using transcriptional analysis we demonstrate that recovery from LPS tolerance (R – Recovery), as defined by cytokine gene expression, is associated with a global change in the transcriptional profile of macrophage. This data confirms that LPS tolerance is a transient state which results in induction of novel hybrid macrophage activation state with a unique transcriptional signature. Bone marrow derived macrophages were polarised into three activation states; Acute response to LPS (A), LPS tolerant (T) and recovered (R). Gene expression was measured at 4 hours post stimulation with LPS. Three independent experiments were performed to measure gene expression changes between each macrophage group.
Project description:Macrophages respond to environmental cues in a plastic manner and play a crucial role in host defense, inflammation, and tissue homeostasis. Macrophage activation undergoes metabolic and transcriptomic reprogramming to adapt and tailor an appropriate response, regulating inflammation. Reactive oxygen species (ROS) have been shown to play a pivotal role in macrophage activation. Nevertheless, the detailed molecular mechanism of how initial redox signals direct macrophage activation is not fully elucidated. Here, we uncover an unconventional role for histone acetyltransferase MOF (also known as KAT8) in regulating LPS-induced macrophage activation via modulating the acetylation of peroxiredoxin 1 (PRDX1), an H2O2 scavenger. We demonstrate that PRDX1 is a novel substrate of MOF and identify the major MOF-mediated acetylation site at lysine 197. K197 acetylation of PRDX1 (K197ac PRDX1) is dynamic and reversely regulated by HDAC6 or SIRT2. We observe that this acetylation is readily diminished in the immediate response to LPS. We demonstrate that K197ac PRDX1 fine-tunes its peroxidase activity, leading to the modulation of intracellular ROS levels in early response to LPS stimulation. Moreover, K197ac PRDX1 specifically regulates ERK1/2 phosphorylation, thereby modulating glycolytic metabolism in inflammatory macrophages. Consequently, K197ac PRDX1 tunes the expression and production of the proinflammatory cytokine, IL-6. Taken together, our findings describe a novel signaling module, MOF-PRDX1-ERK, which regulates LPS-induced macrophage activation at the metabolic and transcriptional levels.