Project description:Carbon monoxide (CO) is an endogenous messenger that suppresses inflammation, modulates apoptosis and promotes vascular remodeling. Here, microarrays were employed to globally characterize the CO (250 ppm) suppression of early (1 h) LPS-induced inflammation in human monocytic THP-1 cells. CO suppressed 79 of 101 immediate-early genes induced by LPS; 19% (15/79) were transcription factors and most others were cytokines, chemokines and immune response genes. The prototypic effects of CO on transcription and protein production occurred early but decreased rapidly. CO activated p38 MAPK, ERK1/2 and Akt and caused an early and transitory delay in LPS-induced JNK activation. However, selective inhibitors of these kinases failed to block CO suppression of LPS-induced IL-1beta, an inflammation marker. Of CO-suppressed genes, 81% (64/79) were found to have promoters with putative NF-kappaB binding sites. CO was subsequently shown to block LPS-induced phosphorylation and degradation of IkappaBalpha in human monocytes, thereby inhibiting NF-kappaB signal transduction. CO broadly suppresses the initial inflammatory response of human monocytes to LPS by reshaping proximal events in TLR4 signal transduction such as stress kinase responses and early NF-kappaB activation. These rapid, but transient effects of CO may have therapeutic applications in acute pulmonary and vascular injury.
Project description:Signal transduction by the NF-kappaB pathway is a key regulator of a host of cellular responses to extracellular and intracellular messages. The NEMO adaptor protein lies at the top of this pathway and serves as a molecular conduit, connecting signals transmitted from upstream sensors to the downstream NF-kappaB transcription factor and subsequent gene activation. The position of NEMO within this pathway makes it an attractive target from which to search for new proteins that link NF-kappaB signaling to additional pathways and upstream effectors. In this work, we have used protein microarrays to identify novel NEMO interactors. A total of 112 protein interactors were identified, with the most statistically significant hit being the canonical NEMO interactor IKKbeta, with IKKalpha also being identified. Of the novel interactors, more than 30% were kinases, while at least 25% were involved in signal transduction. Binding of NEMO to several interactors, including CALB1, CDK2, SAG, SENP2 and SYT1, was confirmed using GST pulldown assays and coimmunoprecipitation, validating the initial screening approach. Overexpression of CALB1, CDK2 and SAG was found to stimulate transcriptional activation by NF-kappaB, while SYT1 overexpression repressed TNFalpha-dependent NF-kappaB transcriptional activation in human embryonic kidney cells. Corresponding with this finding, RNA silencing of CDK2, SAG and SENP2 reduced NF-kappaB transcriptional activation, supporting a positive role for these proteins in the NF-kappaB pathway. The identification of a host of new NEMO interactors opens up new research opportunities to improve understanding of this essential cell signaling pathway.
Project description:The model was constructed to describe TLR4 induced NF-κB activation in native bone marrow-derived macrophages. It included processes of ligand (lipopolysaccharide) recognition, formation of dimer receptor complex and further signal transduction through TRAF6/TAK1 complex that leads to the activation of IKKα/β kinase, which in turn enables the NF-κB transcription factor phosphorylation and translocation in the cell nucleus, and induction of IkB and WIP1 (as an example of induced protein that promotes NF-κB dephosphorylation 2) gene transcription. Models were based on the current knowledge of TLR signaling framework, protein interactions within the TLR4 pathway, and up-to-date mathematical models describing Toll receptor activation.
The major important additions were made to TLR4 signaling description:
1) Receptor dimerization process
2) The existence of a basal nuclear NF-κB level (translocation)
3) NF-κB phosphorylation by IKK complex
Project description:Human intestinal macrophages contribute to tissue homeostasis in noninflamed mucosa through profound down-regulation of pro-inflammatory cytokine release. Here, we show that this down-regulation extends to Toll-like receptor (TLR)-induced cytokine release, as intestinal macrophages expressed TLR3-TLR9 but did not release cytokines in response to TLR-specific ligands. Likely contributing to this unique functional profile, intestinal macrophages expressed markedly down-regulated adapter proteins MyD88 and Toll interleukin receptor 1 domain-containing adapter-inducing interferon beta, which together mediate all TLR MyD88-dependent and -independent NF-kappaB signaling, did not phosphorylate NF-kappaB p65 or Smad-induced IkappaBalpha, and did not translocate NF-kappaB into the nucleus. Importantly, transforming growth factor-beta released from intestinal extracellular matrix (stroma) induced identical down-regulation in the NF-kappaB signaling and function of blood monocytes, the exclusive source of intestinal macrophages. Our findings implicate stromal transforming growth factor-beta-induced dysregulation of NF-kappaB proteins and Smad signaling in the differentiation of pro-inflammatory blood monocytes into noninflammatory intestinal macrophages. Comparison of unstimulated monocytes and macrophages, and flagellin stimulated monocytes and macrophages.
Project description:Signal transduction by the NF-kappaB pathway is a key regulator of a host of cellular responses to extracellular and intracellular messages. The NEMO adaptor protein lies at the top of this pathway and serves as a molecular conduit, connecting signals transmitted from upstream sensors to the downstream NF-kappaB transcription factor and subsequent gene activation. The position of NEMO within this pathway makes it an attractive target from which to search for new proteins that link NF-kappaB signaling to additional pathways and upstream effectors. In this work, we have used protein microarrays to identify novel NEMO interactors. A total of 112 protein interactors were identified, with the most statistically significant hit being the canonical NEMO interactor IKKbeta, with IKKalpha also being identified. Of the novel interactors, more than 30% were kinases, while at least 25% were involved in signal transduction. Binding of NEMO to several interactors, including CALB1, CDK2, SAG, SENP2 and SYT1, was confirmed using GST pulldown assays and coimmunoprecipitation, validating the initial screening approach. Overexpression of CALB1, CDK2 and SAG was found to stimulate transcriptional activation by NF-kappaB, while SYT1 overexpression repressed TNFalpha-dependent NF-kappaB transcriptional activation in human embryonic kidney cells. Corresponding with this finding, RNA silencing of CDK2, SAG and SENP2 reduced NF-kappaB transcriptional activation, supporting a positive role for these proteins in the NF-kappaB pathway. The identification of a host of new NEMO interactors opens up new research opportunities to improve understanding of this essential cell signaling pathway. For microarray screening, Invitrogen Protoarray v4.0 protein microarrays were used. Human NEMO expressed as a C-terminal GST fusion was purified from E. coli lysates and labelled with biotin. NEMO or biotinylated GST were applied to the microarrays and binding partners detected using streptavidin-Alexa Fluor 647. Significant interactors on both arrays were detected using Invitrogen Protoarray Prospector software and a Z-score cutoff of 3.0. Following subtraction of interactors present on the GST control array, a final set of significant NEMO interactors was derived. Full experimental details are supplied in Fenner, B. J., Scannell, M. & Prehn, J. H. M. (2010). Expanding the substantial interactome of NEMO using protein microarrays. PLoS ONE (in press).
Project description:Human intestinal macrophages contribute to tissue homeostasis in noninflamed mucosa through profound down-regulation of pro-inflammatory cytokine release. Here, we show that this down-regulation extends to Toll-like receptor (TLR)-induced cytokine release, as intestinal macrophages expressed TLR3-TLR9 but did not release cytokines in response to TLR-specific ligands. Likely contributing to this unique functional profile, intestinal macrophages expressed markedly down-regulated adapter proteins MyD88 and Toll interleukin receptor 1 domain-containing adapter-inducing interferon beta, which together mediate all TLR MyD88-dependent and -independent NF-kappaB signaling, did not phosphorylate NF-kappaB p65 or Smad-induced IkappaBalpha, and did not translocate NF-kappaB into the nucleus. Importantly, transforming growth factor-beta released from intestinal extracellular matrix (stroma) induced identical down-regulation in the NF-kappaB signaling and function of blood monocytes, the exclusive source of intestinal macrophages. Our findings implicate stromal transforming growth factor-beta-induced dysregulation of NF-kappaB proteins and Smad signaling in the differentiation of pro-inflammatory blood monocytes into noninflammatory intestinal macrophages.
Project description:Transcriptional profiling of human acute myelogenous leukemia (AML) CD34+ cells treated with 5 μM fenretinide. Two timepoints included are 6h, 12h, covering the apoptosis-induction time window of AML CD34+ cells responsing to the fenretinide treatment. We studied gene expression series in human AML CD34+ cells with or without 5 μM fenretinide treatment by cDNA microarray analysis. Several signal transduction pathways are involve, including stress response, NF-kappaB inhibition and p53 inhibition (p<0.05). These findings indicate fenretinide may represent a promising candidate for targeting AML-initiating cells.
Project description:In effort to develop methodology for targeted top down mass spectrometry of NF kappa B p65 from human cells, we evaluated the utility of HaloTag for purification and analysis of recombinant protein. During our study, two datasets of bottom up LC-MS/MS were generated: one from in-gel digestion of the predominant band following p65-HaloTag purification, another from in-solution digestion of all the proteins present in a p65-HaloTag purification. p65-HaloTag copurifying proteins identified in our datasets include the known interactors c-Rel, NF-kappaB p105, NF-kappaB p100, and NF-kappaB inhibitor beta. Over 100 proteins were identified by at least two peptides using a Mascot ion cut-off score of 30.
Project description:Prostaglandin E2 (PGE2) is involved in several inflammatory conditions including periodontitis. The aim of this study was to investigate the global gene expression profile of tumor necrosis factor alpha (TNFalpha) stimulated human gingival fibroblasts, focusing on signal pathways related to PGE2 production and the new PGE2-synthesizing enzymes, prostaglandin E synthases (PGES). The expression of microsomal prostaglandin E synthase-1 (mPGES-1) as well as the upstream cyclooxygenase-2 (COX-2) was up-regulated by TNFalpha, accompanied by increased PGE2 production. In contrast, the expression of microsomal prostaglandin E synthase-2 (mPGES-2) and cytosolic prostaglandin E synthase (cPGES) was unaffected by TNFalpha. Using microarray analysis in a time-course factorial design including time points 1, 3 and 6 h, we identified differentially expressed genes in response to TNFalpha treatment. Enrichment analysis of microarray data identified two positively regulated signal transduction pathways: c-Jun N-terminal kinase (JNK) and Nuclear Factor-kappaB (NF-kappaB). We used specific inhibitors and phosphorylation analysis to confirm their role in PGE2 regulation. Both JNK and NF-kappaB inhibitors reduced the TNFalpha-stimulated up-regulation of mPGES-1 and COX-2 as well as subsequent PGE2 production. The novel finding that TNFalpha-stimulated mPGES-1 is regulated by JNK suggests this kinase as a potential future target for treatment strategies in inflammatory disorders, including periodontitis. Keywords: Time course, gene expression, factorial design.