Project description:Background: In contrast to HIV-1, lentiviruses of the HIV-2/SIVmac/SIVsmm lineage are capable of efficient replication in myeloid cells due to the presence of their accessory protein Vpx. Vpx has been shown to induce degradation of the dNTP triphosphohydrolase SAMHD1, which is a cellular restriction factor of lentiviral replication. Furthermore, Vpx is important for nuclear import of the viral pre-integration complex. To identify further functions of Vpx, we have analyzed the effect of Vpx on cellular gene expression in monocytes. Therefore, we performed whole genome microarray analysis of unstimulated primary human monocytes treated with SIV–based virus-like particles containing Vpx (VLP+Vpx) or lacking Vpx (VLP). Results: Comparison of the gene expression profiles of human monocytes treated with VLP+Vpx and VLP revealed that Vpx down-regulates various genes involved in innate immunity, in particular genes that are known to be regulated by the transcription factor NF-κB. Subsequent analysis of p65 nuclear translocation revealed that Vpx inhibits the VLP-induced activation of NF-κB. Counteraction of NF-κB was also obtained using Vpx mutants lacking the capacity to induce SAMHD1 degradation. Conclusions: Independent of its capacity to induce degradation of SAMHD1, Vpx is involved in regulation of cellular gene expression. In particular, Vpx is able to modulate innate immune responses through down-regulation of TLR-induced NF-κB activation. This points to a significant role of Vpx in the pathogenicity of SIV, as the lower pathogenicity of SIV compared to HIV-1 has been associated to lower innate immunity responses.
Project description:cGAS-STING expression in HEK293T cells could up regulate a series of genes. Above them, Vpx significantly suppressed the NF-κB activated genes but had only a slight influence on the IRF3-activated genes. Diverse HIV-2 and SIV Vpx proteins showed an ability to inhibit DNA sensing-activated innate immune responses, suggesting an evolutionarily conserved function for Vpx.
Project description:Mycobacterium smegmatis is a model non-pathogenic mycobacterium that is efficiently killed by macrophages. Here, we explore the role of NF-κB in the innate immune response, focusing in detail on the mechanisms of the first killing period (1-4h) of M. smegmatis which coincides with phagosome-lysosome fusion. We show that infection of macrophages with M. smegmatis induces an activation of NF-κB and this activation is required for killing since treatment of macrophages with NF-κB inhibitors or siRNA silencing of the NF-κB subunit p65 increases bacterial survival. NF-κB induced proteins were thus hypothesized to be essential during the first phase of M. smegmatis killing. We therefore identified, using RNA microarray, the genes that were regulated during infection in the absence and presence of NF-κB inhibitors. By subtraction this provided a list of pro-inflammatory proteins that were under the control of NF-κB and putatively involved in the killing response. Among these category of genes were those for lysosomal enzymes and membrane trafficking regulators, including Cathepsins, LAMP-2 and Rab34, are regulated by NF-κB. Moreover, inhibition of NF-κB signaling retarded the delivery of v-ATPase, LAMP-2, CtsZ and CtsH thereby impairing the maturation of mycobacterial phagosomes. Collectively; our data provide the first compelling evidence that the innate immune response via NF-κB activation is linked to phagosome fusion with lysosomes that is essential for killing of mycobacteria. Keywords: NFkB inhibitor treated vs untreated
Project description:Mesenchymal stem cells (MSCs) are known to induce the conversion of activated T-cells into regulatory T-cells in vitro. The marker CD69 is a target of canonical NF-κB signaling and is transiently expressed upon activation; however, stable CD69 expression defines cells with immunoregulatory properties. Given its enormous therapeutic potential, we explored the molecular mechanisms underlying the induction of regulatory cells by MSCs. Peripheral blood CD3+ T-cells were activated and cultured in the presence or absence of MSCs. CD4+ cell mRNA expression was then characterized by microarray analysis. The drug BAY11-7082 and a siRNA against RELB were used to explore the differential roles of canonical and non-canonical NF-κB signaling, respectively. Flow cytometry and real-time PCR were used for analyses. Genes with immunoregulatory functions, CD69 and non-canonical NF-κB subunits (RELB and NFKB2) were all expressed at higher levels in lymphocytes co-cultured with MSCs. The frequency of CD69+ cells among lymphocytes cultured alone progressively decreased after activation. In contrast, the frequency of CD69+ cells increased significantly following activation in lymphocytes co-cultured with MSCs. Inhibition of canonical NF-κB signaling by BAY immediately following activation blocked the induction of CD69; however, inhibition of canonical NF-κB signaling on the 3rd day further induced the expression of CD69. Furthermore, late expression of CD69 was inhibited by RELB siRNA. These results indicate that the canonical NF-κB pathway controls the early expression of CD69 after activation; however, in an immunoregulatory context, late and sustained CD69 expression is promoted by the non-canonical pathway and is inhibited by canonical NF-κB signaling. In order to study the molecular basis by which Multipotent Mesenchymal Stromal/Stem Cells (MSC) exert their immune regulatory function, immunomagnetically purified CD3+ T-cells from the peripheral blood of 3 individuals were activated and cultured in the presence or absence of MSCs. Following 5 days, CD4+ and CD8+ T-cells were further immunomagnetically selected and their gene expression profiles were obtained by microarrays and compared. Paired samples from 3 individuals were used for this analysis.
Project description:Gastric mucosa responds to the pathogen Helicobacter pylori (H. pylori) by producing and release of pro-inflammatory cytokines that activate the innate immune system mainly through activation of the transcription factor NF-κB. Although NF-κB signaling is well studied for many possible inducers, induction by H. pylori remains poorly understood. Here, we performed a high-throughput genome-wide RNAi screen for genes influencing H. pylori-induced NF-κB activation. In comparison to TNFα or IL‐1β NF‐κB signaling, we identified 21 proteins unique necessary for H. pylori NF-κB pathway and 24 factors that inhibited the activation. Furthermore, we present here the R/Bioconductor package Nested Effect Model for systematic use in high-throughput screens to classify newly identified factors. We identified alpha kinase 1 (ALPK1) as particular important for the H. pylori NF‐κB pathway without affecting TNFα or IL‐1β signaling. ALPK1 silencing inhibits activity of TAK1 and the IκB kinases (IKKs), degradation of the NF‐κB inhibitor IκBα, nuclear translocation of the NF‐κB subunit p65, and transcription of the NF‐κB target genes, e.g. IL‐8. Thus, we identify ALPK1 as a novel inflammatory regulator functioning particularly in the NF‐κB signaling network activated by H. pylori.
Project description:NF-κB has an essential role in innate immune response and inflammation and is involved in cancer development and progression. We apply the SEC-PCP-SILAC method incorporating metabolic labeling, size exclusion chromatography and protein correlation profiling to construct a complex network of interactome rearrangement in response to NF-κB modulation in breast cancer cells. Our interaction network represents a complex insight into the dynamics of MCF-7 protein interactome associated with NF-κB pathway. Our dataset could serve as a basis for future studies characterizing role of NF-κB in breast cancer cellular pathways. This PRIDE project includes results from SILAC labeled and label-free replicates from the SEC-PCP-SILAC analysis of protein complexes in MCF-7 cells with inhibited and uninhibited NF-κB pathway, results from the immunoprecipitation experiment aimed at interaction partners of NF-κB factor RELA, analysis of total proteome after NF-κB inhibition, and results from SEC fractionation of untreated and unlabeled MCF-7 cells.
Project description:In acute HIV infection immune activation may provide target cells and drive virus replication, which innate immunity may limit. Thus, the net effects of inflammatory mediators, including type I interferon (IFN-I), are unclear. Here, we block IFN-I signaling during pathogenic acute SIV infection with an IFN-I receptor antagonist. Delayed antiviral gene expression, increased SIV reservoir, increased CD4 T cell depletion and accelerated progression to AIDS and death ensue despite decreased T cell activation. In contrast, IFNα2a treatment initially upregulates antiviral genes and prevents systemic SIV infection after rectal challenge. Antiviral gene expression normalizes, and infection ensues with fewer transmitted/founder variants. Continued IFNα2a treatment causes delayed antiviral gene expression, increased SIV reservoir and increased CCR5+ CD4 T cell loss. Thus, the precise timing of antiviral gene expression has a profound impact on disease course. The benefits of early antiviral activity outweigh the harms of increased immune activation in acute SIV infection. SRA Study accession: SRP034563, BioProject ID:PRJNA231884
Project description:Cordyceps participates in various pharmacological activities including anti-tumor, and is involved in the regulation of NF-κB signaling pathway. However, the detailed role of cordycepin in suppression of NF-κB signaling pathway is less clear. In this study, we first analyzed the effect of cordyceps on NF-κB activity in TK-10 cells, and found that cordyceps resulted in a dose-dependent reduction in TNF-α-induced NF-κB activation. Here, we show that cordyceps mediated NF-kB inhibition induces apoptosis in TK-10 cells involved the serial activation of caspases. Moreover, we demonstrate that in addition to activating caspases, the cordyceps negatively modulates TNF-α-mediated NF-κB signaling to promote JNK activation, which results in apoptosis, and that NF-kB regulates antiapoptotic factor GADD45b and the JNK kinase MKK7. When the TNFα cytokine binds to the TNF receptor, IκB dissociates from NF-κB. As a result, the active NF-κB translocates to the nucleus. Cordyceps clearly prevented NF-κB from mobilizing to the nucleus, resulting in downregulation of GADD45b, whereas upregulation of MKK7 and phosphorylation of JNK (p-JNK). This increased Bax activation, leading to marked cordyceps-induced apoptosis. Bax subfamily proteins induced apoptosis through caspase-3. Furthermore, siRNA mediated inhibition of MKK7 downregulated p-JNK and The JNK inhibitor SP600125 strongly inhibited Bax. Thus, these results indicate that cordyceps inhibits NF-κB/GADD45b signaling activation to upregulate MKK7-JNK signaling pathway to induce apoptosis in TK-10 cells and support the potential of cordyceps as a therapeutic agent for renal cancer.
Project description:Natural SIV infection of sooty mangabeys (SMs) does not progress to disease despite chronic virus replication. In contrast to pathogenic SIV infection of rhesus macaques (RMs), chronic SIV infection of SMs is characterized by low immune activation. To elucidate the mechanisms underlying this phenotype, we longitudinally assessed host gene expression in SIV-infected SMs and RMs. We found that acute SIV infection of SMs is consistently associated with a robust innate immune response, including widespread up-regulation of interferon-stimulated genes (ISGs). Our findings indicate that active immune regulatory mechanisms, rather than intrinsically attenuated innate immune responses, underlie the low immuneactivation of chronically SIV-infected SMs. We infected 5 SMs with SIVsmm and assessed their gene expression in RNA derived from whole blood at 3,7,10,14,30 and 180 days post-infection using Rhesus Affymetrix GeneChips. As a comparison, we also analyzed gene expression in 4 RMs infected with SIVsmm, and 8 RMs infected with SIVmac239, a classical pathogenic SIV.