Search results for "regulator"
showing 10 items of 1009 documents
Survival of Listeria monocytogenes in Soil Requires AgrA-Mediated Regulation
2015
ABSTRACT In a recent paper, we demonstrated that inactivation of the Agr system affects the patterns of survival of Listeria monocytogenes (A.-L. Vivant, D. Garmyn, L. Gal, and P. Piveteau, Front Cell Infect Microbiol 4:160, http://dx.doi.org/10.3389/fcimb.2014.00160 ). In this study, we investigated whether the Agr-mediated response is triggered during adaptation in soil, and we compared survival patterns in a set of 10 soils. The fate of the parental strain L. monocytogenes L9 (a rifampin-resistant mutant of L. monocytogenes EGD-e) and that of a Δ agrA deletion mutant were compared in a collection of 10 soil microcosms. The Δ agrA mutant displayed significantly reduced survival in these b…
Crosstalk of regulatory T cells and tolerogenic dendritic cells prevents contact allergy in subjects with low zone tolerance
2012
Background Allergic contact dermatitis is one of the most common occupational diseases. A main protective mechanism in those who do not develop allergic contact dermatitis is tolerance induction by repeated exposure to low doses of contact allergen, which is termed low zone tolerance (LZT). The mechanisms that determine the tolerance induction in subjects with LZT are still elusive. Objective We performed analysis of the role of CD4 + CD25 + forkhead box protein 3 (FOXP3)–positive regulatory T (Treg) cells and dendritic cells (DCs) in mice with LZT. Methods Mechanisms of tolerance induction were analyzed in a murine model of LZT by using FOXP3 and IL-10 reporter mice, as well as mice that a…
Regulatory T cells selectively preserve immune privilege of self-antigens during viral central nervous system infection.
2012
Abstract Regulatory T cells (Tregs) are important for the attenuation of immune reactions. During viral CNS infections, however, an indiscriminate maintenance of CNS immune privilege through Treg-mediated negative regulation could prevent autoimmune sequelae but impair the control of viral replication. We analyzed in this study the impact of Tregs on the development of acute viral encephalomyelitis, T cell-mediated antiviral protection, and prevention of CNS autoimmunity following intranasal infection with the gliatropic mouse hepatitis virus strain A59. To assess the contribution of Tregs in vivo, we specifically depleted CD4+Foxp3+ T cells in a diphtheria toxin-dependent manner. We found …
C-X-C Motif Chemokine Receptor 4 Blockade Promotes Tissue Repair After Myocardial Infarction by Enhancing Regulatory T Cell Mobilization and Immune-R…
2019
Background: Acute myocardial infarction (MI) elicits an inflammatory response that drives tissue repair and adverse cardiac remodeling. Inflammatory cell trafficking after MI is controlled by C-X-C motif chemokine ligand 12 (CXCL12) and its receptor, C-X-C motif chemokine receptor 4 (CXCR4). CXCR4 antagonists mobilize inflammatory cells and promote infarct repair, but the cellular mechanisms are unclear. Methods: We investigated the therapeutic potential and mode of action of the peptidic macrocycle CXCR4 antagonist POL5551 in mice with reperfused MI. We applied cell depletion and adoptive transfer strategies using lymphocyte-deficient Rag1 knockout mice; DEREG mice, which express a diphth…
SAHA/TRAIL combination induces detachment and anoikis of MDA-MB231 and MCF-7 breast cancer cells
2012
Abstract SAHA, an inhibitor of histone deacetylase activity, has been shown to sensitize tumor cells to apoptosis induced by TRAIL, a member of TNF-family. In this paper we investigated the effect of SAHA/TRAIL combination in two breast cancer cell lines, the ERα−positive MCF-7 and the ERα−negative MDA-MB231. Treatment of MDA-MB231 and MCF-7 cells with SAHA in combination with TRAIL caused detachment of cells followed by anoikis, a form of apoptosis which occurs after cell detachment, while treatment with SAHA or TRAIL alone did not produce these effects. The effects were more evident in MDA-MB231 cells, which were chosen for ascertaining the mechanism of SAHA/TRAIL action. Our results show…
Inducible and reversible inhibition of miRNA-mediated gene repression in vivo
2021
Although virtually all gene networks are predicted to be controlled by miRNAs, the contribution of this important layer of gene regulation to tissue homeostasis in adult animals remains unclear. Gain and loss of function experiments have provided key insights into the specific function of individual miRNAs, but effective genetic tools to study the functional consequences of global inhibition of miRNA activity in vivo are lacking. Here we report the generation and characterization of a genetically engineered mouse strain in which miRNA-mediated gene repression can be reversibly inhibited without affecting miRNA biogenesis or abundance. We demonstrate the usefulness of this strategy by invest…
The arbuscular mycorrhizal symbiosis promotes the systemic induction of regulatory defence-related genes in rice leaves and confers resistance to pat…
2011
Arbuscular mycorrhizal (AM) symbioses are mutualistic associations between soil fungi and most vascular plants. Their association benefits the host plant by improving nutrition, mainly phosphorus nutrition, and by providing increased capability to cope with adverse conditions. In this study, we investigated the transcriptional changes triggered in rice leaves as a result of AM symbiosis, focusing on the relevance of the plant defence response. We showed that root colonization by the AM fungus Glomus intraradices is accompanied by the systemic induction of genes that play a regulatory role in the host defence response, such as OsNPR1, OsAP2, OsEREBP and OsJAmyb. Genes involved in signal tran…
Respiration and low cAMP-dependent protein kinase activity are required for high-level expression of the peroxisomal thiolase gene in Saccharomyces c…
1996
Transcription of genes for peroxisomal proteins is repressed by glucose and induced by oleate. At least for the peroxisomal thiolase gene (POT1) there is a third regulatory mechanism, mediated by the transcription factor Adr1p, which is responsible for the high-level expression of the gene in stationary phase. Here we show that a region in the POT1 promoter that extends from positions -238 to -152 mediates this mechanism, and we suggest that Adr1p acts indirectly on POT1. We have also analyzed the role of the cAMP-dependent protein kinase (PKA) in the transcriptional regulation of POT1. PKA exerts a negative control: the high, unregulated PKA activity in a bcy1 mutant maintains POT1 transcr…
Cutting Edge: Trans-Signaling via the Soluble IL-6R Abrogates the Induction of FoxP3 in Naive CD4+CD25− T Cells
2007
Abstract Chronic inflammatory diseases may develop when regulatory T cells (Tregs) fail to control the balance between tolerance and immunity. Alternatively, activated immune cells might prevent the induction or activation of Tregs in such diseases. In this study, we demonstrate that trans-signaling into T cells via the soluble IL-6 receptor completely abrogates the de novo induction of adaptive Tregs. Mechanistically, IL-6 trans-signaling augmented the expression of the TGF-β signaling inhibitor SMAD7. Consequently, SMAD7 overexpression in T cells using newly created transgenic mice rendered CD4+CD25− T cells resistant to the induction of FoxP3. Finally, IL-6 trans-signaling inhibited Treg…
Large scale preparation of human MHC class II+ integrin beta(1)+ Tregs.
2010
Abstract The human CD4 + CD25 + FoxP3 + regulatory T cell population (Tregs) contains both MHC class II + and MHC class II − cells. MHC class II + Tregs belong to the integrin α 4 β 1 + subpopulation and exclusively execute contact-dependent suppressive activity. Here we present a method optimized for isolation of these MHC class II expressing Tregs from large leukaphereses products using magnetic microbeads that achieves a reproducible purity of more than 90% and enables the use of this small-sized Treg population in pre-clinical application and basic research.