Project description:The gene expression levels in murine bone marrow-derived dendritic cells treated with γ-PGA NPs were examined by oligonucleitide microarray and compared with those in the cells treated with other adjuvants. The gene expression of proinflammatory chemokines, cytokines, and costimulatory molecules was upregulated considerably in DCs treated with γ-PGA NPs. The upregulation pattern was similar to that in DCs treated with LPS but not in DCs treated with unparticulate γ-PGA. The activation of DCs by γ-PGA NPs was confirmed by real-time RT-PCR analysis for the genes related to TLR signaling. The effect of γ-PGA NPs on DCs was not annihilated by treating with polymixin B, an inhibitor of LPS. Furthermore, the immunization of mice with γ-PGA NPs carrying OVA significantly induced Ag-specific CD8+ T cells and Ag-specific production of IL-2, TNF-α, and IFN-γ from the cells. Such activities of γ-PGA NPs were more prominent, when compared to the immunization with OVA plus aluminum hydroxide or OVA plus CFA. These results suggest that γ-PGA NPs induce a CD8+ T cell response through activating innate immunity in a fashion different from that of LPS. Thus, γ-PGA NPs may be an attractive adjuvant to be further developed for vaccine therapy. Overall design: The gene expression in murine bone marrow-derived dendritic cell was measured at 6 hours after exposure to γ-PGA NPs (300 µg/ml), LPS(1 µg/ml ), or unparticulate γ-PGA(300 µg/ml). Three independent experiments were performed.
Project description:Clinical isolates of the porcine pathogen Actinobacillus pleuropneumoniae often form adherent colonies on agar plates due to expression of an operon, pgaABCD, encoding a poly-N-acetylglucosamine (PGA) extracellular matrix. The adherent colony phenotype, which correlates with the ability to form a biofilm on the surface of polystyrene plates, is lost following serial passage in broth culture, and repeated passage of the non-adherent variants on solid media does not result in reversion to the adherent colony phenotype. In order to investigate the regulation of PGA expression and biofilm formation in A. pleuropneumoniae, we screened a bank of transposon mutants of the non-adherent serovar 1 strain, S4074T, and identified mutations in two genes, rseA and hns, which resulted in formation of the adherent colony phenotype. In other bacteria, including the Enterobacteriaceae, H-NS acts as a global gene regulator, and RseA is a negative regulator of the extracytoplasmic stress response sigma factor, ?E. Transcription profiling of A. pleuropneumoniae rseA and hns mutants revealed that both ?E and H-NS independently regulate expression of the pga operon. Transcription of the pga operon is initiated from a ?E promoter site in the absence of H-NS, and up-regulation of ?E is sufficient to displace H-NS, allowing transcription to proceed. In A. pleuropneumoniae, H-NS does not act as a global gene regulator, but rather specifically regulates biofilm formation via repression of the pga operon. Positive regulation of the pga operon by ?E indicates that biofilm formation in is part of the extracytoplasmic stress response in A. pleuropneumoniae.
Project description:The gene expression levels in murine bone marrow-derived dendritic cells treated with γ-PGA NPs were examined by oligonucleitide microarray at 6, 12 and 24 hours. The gene expression of proinflammatory chemokines, cytokines, and costimulatory molecules was upregulated considerably in DCs treated with γ-PGA NPs at 6 hours. Overall design: The gene expression in murine bone marrow-derived dendritic cell was measured at 6, 12 and 24 hours after exposure to γ-PGA NPs (300 µg/ml). Three independent experiments were performed.
Project description:We identified the D-galacturonic acid (GA) responsive transcriptional activator GaaR of the saprotrophic fungus Aspergillus niger, which was found to be essential for growth on GA and polygalacturonic acid (PGA). Growth of the ΔgaaR strain was reduced on complex pectins. Genome-wide expression analysis showed that GaaR is required for the expression of genes necessary to release GA from PGA and more complex pectins, to transport GA into the cell and to induce the GA-catabolic pathway. Residual growth of ΔgaaR on complex pectins is likely due to expression of pectinases acting on rhamnogalacturonan and subsequent metabolism of the monosaccharides other than GA. Overall design: The GA-responsive transcriptional activator GaaR of A. niger was identified by in-silico homology search. Deletion analysis and transcriptomic profiling studies performed in this study showed that the A. niger GaaR ortholog is required for growth on GA and PGA and for the induction of the GA-regulon when grown on sugar beet pectin.
Project description:We analyze the transcriptomic response of the phytopathogenic enterobacterium Dickeya dadantii to a DNA supercoiling relaxation shock using the gyrase inhibitor novobiocin. The shock was applied to Dickeya cells grown in minimal medium supplemented with sucrose, in exponential or transition to stationary phase, and in minimal medium with sucrose + PGA (a pectin derivative) in transition to stationary phase.