Inflammasome activation is critical for host defense against various microbial infections. Activation of the NLRC4 inflammasome requires detection of flagellin or type III secretion system (T3SS) components by NLR family apoptosis inhibitory proteins (NAIPs); yet how this pathway is regulated is unknown. Here we found that interferon regulatory factor 8 (IRF8) is required for optimal activation of the NLRC4 inflammasome in bone marrow-derived macrophages infected with Salmonella Typhimurium, Burkholderia thailandensis, or Pseudomonas aeruginosa but is dispensable for activation of the canonical and non-canonical NLRP3, AIM2, and Pyrin inflammasomes. IRF8 governs the transcription of Naips to allow detection of flagellin or T3SS proteins to mediate NLRC4 inflammasome activation. Furthermore, we found that IRF8 confers protection against bacterial infection in vivo, owing to its role in inflammasome-dependent cytokine production and pyroptosis. Altogether, our findings suggest that IRF8 is a critical regulator of NAIPs and NLRC4 inflammasome activation for defense against bacterial infection.
IRF8 Regulates Transcription of Naips for NLRC4 Inflammasome Activation.
No sample metadata fields
View SamplesLysosomal cathepsins regulate an exquisite range of biological functions, and their deregulation is associated with inflammatory, metabolic and degenerative disease in humans. Here, we identified a key cell-intrinsic role for cathepsin B as a negative feedback regulator of lysosomal biogenesis and autophagy. Mice and macrophages lacking cathepsin B activity had increased resistance to the cytosolic bacterial pathogen Francisella novicida. Genetic deletion or pharmacological inhibition of cathepsin B downregulated mTOR activity and prevented cleavage of the lysosomal calcium channel TRPML1. These events drove transcription of lysosomal and autophagy genes via the transcription factor TFEB, which increased lysosomal biogenesis and activation of autophagy-initiation kinase ULK1 for clearance of the bacteria. Our results identified a fundamental biological function of cathepsin B in providing a checkpoint for homeostatic maintenance of lysosome population and basic recycling functions in the cell.
Cathepsin B modulates lysosomal biogenesis and host defense against Francisella novicida infection.
Specimen part
View SamplesThe lack of mouse models permitting the specific ablation of tissue-resident macrophages and monocyte-derived cells complicates understanding of their contribution to tissue integrity and to immune responses. Here we use a new model permitting diphtheria-toxin (DT)-mediated depletion of those cells and in which dendritic cells are spared. We showed that the myeloid cells of the mouse ear skin dermis are dominated by a population of melanin-laden macrophages, called melanophages, that has been missed in most previous studies. By using gene expression profiling, DT-mediated ablation and parabiosis, we determined their identity including their similarity to other skin macrophages, their origin and their dynamics. Limited information exist on the identity of the skin cells responsible for long-term tattoo persistence. Benefiting of our knowledge on melanophages, we showed that they are responsible for retaining tattoo pigment particles through a dynamic process which characterization has direct implications for improving strategies aiming at removing tattoos.
Unveiling skin macrophage dynamics explains both tattoo persistence and strenuous removal.
Specimen part, Treatment
View SamplesThe aim of the dataset was to study on a genome-wide level the impact of Lat deficiency on gene expression in resting and activated CD4+ T cells
Quantitative proteomics analysis of signalosome dynamics in primary T cells identifies the surface receptor CD6 as a Lat adaptor-independent TCR signaling hub.
Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
NALP3 inflammasome upregulation and CASP1 cleavage of the glucocorticoid receptor cause glucocorticoid resistance in leukemia cells.
Disease, Cell line, Treatment
View SamplesGlucocorticoids are universally used in the treatment of acute lymphoblastic leukemia (ALL), and glucocorticoid resistance in leukemia cells confers a poor prognosis. To elucidate mechanisms of glucocorticoid resistance, we determined the prednisolone sensitivity of primary leukemia cells from 444 newly diagnosed ALL patients and found significantly higher expression of caspase 1 (CASP1) and its activator NLRP3 in glucocorticoid resistant leukemia cells, due to significantly lower somatic methylation of CASP1 and NLRP3 promoters. Over-expression of CASP1 resulted in cleavage of the glucocorticoid receptor, diminished glucocorticoid-induced transcriptional response and increased glucocorticoid resistance. Knockdown or inhibition of CASP1 significantly increased glucocorticoid receptor levels and mitigated glucocorticoid resistance in CASP1 overexpressing ALL. Our findings establish a new mechanism by which the NLRP3/CASP1 inflammasome modulates cellular levels of the glucocorticoid receptor and diminishes cell sensitivity to glucocorticoids. The broad impact on glucocorticoid transcriptional response suggests this mechanism could also modify glucocorticoid effects in other diseases.
NALP3 inflammasome upregulation and CASP1 cleavage of the glucocorticoid receptor cause glucocorticoid resistance in leukemia cells.
No sample metadata fields
View SamplesGlucocorticoids are universally used in the treatment of acute lymphoblastic leukemia (ALL), and glucocorticoid resistance in leukemia cells confers a poor prognosis. To elucidate mechanisms of glucocorticoid resistance, we determined the prednisolone sensitivity of primary leukemia cells from 444 newly diagnosed ALL patients and found significantly higher expression of caspase 1 (CASP1) and its activator NLRP3 in glucocorticoid resistant leukemia cells, due to significantly lower somatic methylation of CASP1 and NLRP3 promoters. Over-expression of CASP1 resulted in cleavage of the glucocorticoid receptor, diminished glucocorticoid-induced transcriptional response and increased glucocorticoid resistance. Knockdown or inhibition of CASP1 significantly increased glucocorticoid receptor levels and mitigated glucocorticoid resistance in CASP1 overexpressing ALL. Our findings establish a new mechanism by which the NLRP3/CASP1 inflammasome modulates cellular levels of the glucocorticoid receptor and diminishes cell sensitivity to glucocorticoids. The broad impact on glucocorticoid transcriptional response suggests this mechanism could also modify glucocorticoid effects in other diseases.
NALP3 inflammasome upregulation and CASP1 cleavage of the glucocorticoid receptor cause glucocorticoid resistance in leukemia cells.
No sample metadata fields
View SamplesGlucocorticoids are universally used in the treatment of acute lymphoblastic leukemia (ALL), and glucocorticoid resistance in leukemia cells confers a poor prognosis. To elucidate mechanisms of glucocorticoid resistance, we determined the prednisolone sensitivity of primary leukemia cells from 444 newly diagnosed ALL patients and found significantly higher expression of caspase 1 (CASP1) and its activator NLRP3 in glucocorticoid resistant leukemia cells, due to significantly lower somatic methylation of CASP1 and NLRP3 promoters. Over-expression of CASP1 resulted in cleavage of the glucocorticoid receptor, diminished glucocorticoid-induced transcriptional response and increased glucocorticoid resistance. Knockdown or inhibition of CASP1 significantly increased glucocorticoid receptor levels and mitigated glucocorticoid resistance in CASP1 overexpressing ALL. Our findings establish a new mechanism by which the NLRP3/CASP1 inflammasome modulates cellular levels of the glucocorticoid receptor and diminishes cell sensitivity to glucocorticoids. The broad impact on glucocorticoid transcriptional response suggests this mechanism could also modify glucocorticoid effects in other diseases.
NALP3 inflammasome upregulation and CASP1 cleavage of the glucocorticoid receptor cause glucocorticoid resistance in leukemia cells.
No sample metadata fields
View SamplesRNAPII pausing/termination shortly after initiation is a hallmark of gene regulation. However, the molecular mechanisms involved are still to be uncovered. Here, we show that NELF interacts with Integrator complex subunits (INTScom) forming a stable complex with RNPII and Spt5. The interaction between NELF and INTScom subunits is RNA and DNA independent. Using both HIV-1 promoter and genome wide analyses, we demonstrate that Integrator subunits specifically control NELF-mediated RNAPII pause/release at coding genes. The strength of RNAPII pausing is determined by the nature of the NELF-associated complex. Interestingly, in addition to controlling RNAPII pause release INTS11 catalytic subunit of the INTScom is required for the synthesis of full length mRNA. Finally, INTScom-target genes are enriched in HIV-1 TAR/ NELF-binding element and in a 3'box sequence required for snRNA biogenesis. Revealing these unexpected functions of INTScom in regulating RNAPII pausing/release and completion of mRNA synthesis of NELF-target genes will contribute to our understanding of the gene expression cycle. Overall design: Genome-wide expression in HeLa cells in the absence of Integrator 11, or NELF or mock (control) depleted by strand-specific RNASeq (Illumina)
Integrator complex regulates NELF-mediated RNA polymerase II pause/release and processivity at coding genes.
No sample metadata fields
View SamplesPsoriasis is a chronic inflammatory skin disease of unknown etiology. Although macrophages and dendritic cells (DCs) have been proposed to drive the psoriatic cascade, their largely overlapping phenotype hampered studying their respective role. Topical application of Imiquimod, a Toll-like receptor 7 agonist, induces psoriasis in patients and psoriasiform inflammation in mice. We showed that daily application of Imiquimod for 14 days recapitulated both the initiation and the maintenance phase of psoriasis. Based on our ability to discriminate Langerhans cells (LCs), conventional DCs, monocytes, monocyte-derived DCs and macrophages in the skin, we characterized their dynamics during both phases of psoriasis. During the initiation phase, neutrophils infiltrated the epidermis whereas monocytes and monocyte-derived DCs were predominant in the dermis. During the maintenance phase, LCs and macrophage numbers increased in the epidermis and dermis, respectively. LC expansion resulted from local proliferation, a conclusion supported by transcriptional analysis. Continuous depletion of LCs during the course of Imiquimod treatment aggravated chronic psoriatic symptoms as documented by an increased influx of neutrophils and a stronger inflammation. Therefore, by developing a mouse model that mimics the human disease more accurately, we established that LCs play a negative regulatory role during the maintenance phase of psoriasis.
Dynamics and Transcriptomics of Skin Dendritic Cells and Macrophages in an Imiquimod-Induced, Biphasic Mouse Model of Psoriasis.
Specimen part, Treatment
View Samples