Project description:Gene expression analysis of wild-type and STING knock-out mouse bone marrow-derived macrophages (mBMDM) infected with Brucella abortus or transfected with Brucella abortus DNA. Genes whose expression are affected by Brucella abortus in a STING-dependent manner will be identified and signaling pathways regulated by STING will be elucidated.
Project description:We describe the isolation of sufficient Brucella abortus RNA from primary host cell environment using modified reported methods for RNA-seq analysis, and simultaneously characterize the transcriptional profiles of intracellular B. abortus and bone marrow-derived macrophages (BMM) from BALB/c mice at 24 h (replicative phase) post-infection.
Project description:Isogenic deletion and truncation of specific genes encoding RNases in Brucella abortus were analyzed for changes in gene expression. The main goal of this work is to determine the mRNAs that exhibit dysregulation when small regulatory RNAs (i.e., Bsr8) or RNases (i.e., RNaseE and RNaseJ) are invactivated in Brucella abortus. Small regulatory RNAs often control gene expression by binding directly to mRNAs to block translation or induce their degradation, and RNA from a deletion of one sRNA gene, bsr8, was analyzed to uncover the mRNAs that may be controlled by BsrB. RNases are enzymes that cleave RNAs during processing, turnover, and regulatory events, and RNaseE and RNaseJ appear to be important for B. abortus virulence. Therefore, to determine the mRNAs potentially targetd by these RNases, RNA from a strain harboring a RNaseE truncation and a strain carrying a deletion of rnaseJ were analyzed. In the end, the objective of this study was to gain insight into the regulatory patterns of specific B. abortus sRNAs and RNases.
Project description:Identification of host responses at the gene transcription level provides a molecular profile of the events that occur following infection. Brucella abortus is a facultative intracellular pathogen of macrophages that induces chronic infection in humans and domestic animals. Using microarray technology, the response of macrophages 4 hours following B. abortus infection was analyzed to identify early intracellular infection events that occur in macrophages. Of the more than 6,000 genes, we identified over 140 genes that were reproducibly differentially transcribed. First, an increase in the transcription of a number of pro-inflammatory cytokines and chemokines, such as TNF-α, IL-1β, IL-1α, and members of the SCY family of proteins, was evident that may constitute a general host recruitment of antibacterial defenses. Alternatively, Brucella may subvert newly arriving macrophages for additional intracellular infection. Second, transcription of receptors and cytokines associated with antigen presentation, e.g., MHC class II and IL-12p40, were not evident at this 4 hour period of infection. Third, Brucella inhibited transcription of various host genes involved in apoptosis, cell cycling, and intracellular vesicular trafficking. Identification of macrophage genes whose transcription was inhibited suggests that Brucella utilizes specific mechanisms to target certain cell pathways. In conclusion, these data suggest that B. abortus can alter macrophage pathways to recruit additional macrophages for future infection while simultaneously inhibiting apoptosis and innate immune mechanisms within the macrophage permitting intracellular survival of the bacterium. These results provide insights into the pathogenic strategies used by Brucella to survive long-term within a hostile environment. Keywords: Macrophage, intracellular pathogen, Brucella abortus, inflammatory immune response