The success of many pathogens relies on their ability to circumvent the innate and adaptive immune defenses. How bacterial pathogens subvert host responses is not clear. Cholesterol-dependent cytolysins (CDCs) represent an expansive family of homologous pore-forming toxins produced by more than 20 Gram-positive bacterial species. Here we show that listeriolysin O (LLO), a prototype CDC produced by Listeria monocytogenes, inhibits antigen receptor-induced T cell proliferation. In vivo proliferation of OT II T cells was highly diminished in the presence of wild type but not the LLO-deficient bacteria. T cells pre-exposed to LLO ex vivo were also impaired in proliferation upon TCR activation in vivo and in vitro. Our results suggest that LLO-induced T cell unresponsiveness is due to the sub-threshold activation of T cells via the induction of a calcium-NFAT dependent transcriptional program that drives the expression of negative regulators of TCR signaling.
Listeria monocytogenes induces T cell receptor unresponsiveness through pore-forming toxin listeriolysin O.
Specimen part, TreatmentView Samples
Although mast cells elicit proinflammatory and type I IFN responses upon VSV infection, in response to L.monocytogenes (L.m) or S. Typhimurium (S.t), such cells elicit a transcriptional program devoid of type I IFN response.
Mast cells elicit proinflammatory but not type I interferon responses upon activation of TLRs by bacteria.
Specimen partView Samples
Type I Interferons encompasses a large family of closely related cytokines comprising of at least 13 IFN- isotypes and single IFN-. Both IFN- and IFN- exert their activity through a common receptor IFNAR. Type I Interferons have broad regulatory effects and various subtypes of dendritic cells are influenced by this cytokines. In our study we asked question whether the low, constitutive levels of type I Interferons produced under steady state conditions are important for proper function of splenic conventional dendritic cells.
Absence of IFN-beta impairs antigen presentation capacity of splenic dendritic cells via down-regulation of heat shock protein 70.
Sex, Age, Specimen partView Samples
Notch activation is instrumental in the development of most T-cell acute lymphoblastic leukemia (T-ALL) cases, yet Notch mutations alone are not sufficient to recapitulate the full human disease in animal models. We here found that Notch1 activation at the fetal liver (FL) stage expanded the hematopoietic progenitor population and conferred it transplantable leukemic-initiating capacity. However, leukemogenesis and leukemic-initiating cell capacity induced by Notch1 was critically dependent on the levels of ß-Catenin in both FL and adult bone marrow contexts. In addition, inhibition of ß-Catenin compromised survival and proliferation of human T-ALL cell lines carrying activated Notch1. By transcriptome analyses, we identified the MYC pathway as a crucial element downstream of ß-Catenin in these T-ALL cells and demonstrate that the MYC 3'' enhancer required ß-Catenin and Notch1 recruitment to induce transcription. Finally, PKF115-584 treatment prevented and partially reverted leukemogenesis induced by active Notch1. Overall design: Four T-ALL cell lines (RPMI8402, HPB-ALL, Jurkat, CCRF-CEM) were treated with DMSO (control) or PKF115-584 (310nM) for 3hrs. Gene expression changes were measured with Cufflinks comparing the 4 control with the 4 treated samples.
β-Catenin is required for T-cell leukemia initiation and MYC transcription downstream of Notch1.
No sample metadata fieldsView Samples
The bHLH transcription factor stem cell leukemia gene (Scl) is a master regulator for hematopoiesis essential for hematopoietic specification and proper differentiation of the erythroid and megakaryocyte lineages. However, the critical downstream targets of Scl remain undefined. Here, we identified a novel Scl target gene, transcription factor myocyte enhancer factor 2 C (Mef2C) from Sclfl/fl fetal liver progenitor cell lines. Analysis of Mef2C-/- embryos showed that Mef2C, in contrast to Scl, is not essential for specification into primitive or definitive hematopoietic lineages. However, adult VavCre+Mef2Cfl/fl mice exhibited platelet defects similar to those observed in Scl deficient mice. The platelet counts were reduced, while platelet size was increased and the platelet shape and granularity was altered. Furthermore, megakaryopoiesis was severely impaired in vitro. ChIP-on-chip analysis revealed that Mef2C is directly regulated by Scl in megakaryocytic cells, but not in erythroid cells. In addition, an Scl independent requirement for Mef2C in B-lymphoid homeostasis was observed in Mef2C-deficient mice, characterized as severe age-dependent reduction of specific B cell progenitor populations reminiscent of premature aging. In summary, this work identifies Mef2C as an integral member of hematopoietic transcription factors with distinct upstream regulatory mechanisms and functional requirements in megakaryocyte and B-lymphoid lineages.
Mef2C is a lineage-restricted target of Scl/Tal1 and regulates megakaryopoiesis and B-cell homeostasis.
No sample metadata fieldsView Samples
The routine workflow for invasive cancer diagnostics is based on biopsy processing by formalin fixation and subsequent paraffin embedding. Formalin-fixed paraffin-embedded (FFPE) tissue samples are easy to handle, stable and particularly suitable for morphologic evaluation, immunohistochemistry and in situ hybridization. However, it has become a paradigm that these samples cannot be used for genome-wide expression analysis with microarrays. To oppose this view, we present a pilot microarray study using FFPE core needle biopsies from breast cancers as RNA source. We found that microarray probes interrogating sequences near the poly-A-tail of the transcribed genes were well suitable to measure RNA levels in FFPE core needle biopsies. For the ER and the HER2 gene, we observed strong correlations between RNA levels measured in these probe sets and protein expression determined by immunohistochemistry (p = 0.000003 and p = 0.0022). Further, we have identified a signature of 364 genes that correlated with ER protein status and a signature of 528 genes that correlated with HER2 protein status. Many of these genes (ER: 60%) could be confirmed by analysis of an independent publicly available data set. Finally, a hierarchical clustering of the biopsies with respect to three recently reported gene expression grade signatures resulted in widely stable low and high expression grade clusters that correlated with the pathological tumor grade. These findings support the notion that clinically relevant information can be gained from microarray based gene expression profiling of FFPE cancer biopsies. This opens new opportunities for the integration of gene expression analysis into the workflow of invasive cancer diagnostics as well as translational research in the setting of clinical studies.
Genome-wide gene expression profiling of formalin-fixed paraffin-embedded breast cancer core biopsies using microarrays.
Disease stageView Samples
Purpose: To investigate the effect of transcorneal electrical stimulation (TES) on the retina of wildtype Brown Norway (BN) rats by gene expression profiling.
Gene expression profiling of the retina after transcorneal electrical stimulation in wild-type Brown Norway rats.
Sex, AgeView Samples