Project description:This study uses microarray analyses to examine transcriptional responses of Mycobacterium tuberculosis complex clinical isolates to phagosomal cues encountered inside resting murine bone marrow-derived macrophages 24hr post-infection. Transcript levels of intracellular mycobacteria were compared to extracellular bacteria of the same strain (An aliquot of the inoculum used to infect macrophages was incubated in the absence of macrophages for 24hr in an identical flask). Set of arrays that are part of repeated experiments Keywords: Biological Replicate Biological Replicate Computed
Project description:This study uses microarray analyses to examine transcriptional responses of Mycobacterium tuberculosis complex clinical isolates to phagosomal cues encountered inside resting murine bone marrow-derived macrophages 24hr post-infection. Transcript levels of intracellular mycobacteria were compared to extracellular bacteria of the same strain (An aliquot of the inoculum used to infect macrophages was incubated in the absence of macrophages for 24hr in an identical flask). Set of arrays that are part of repeated experiments Keywords: Biological Replicate
Project description:This study uses microarray analyses to examine transcriptional responses of Mycobacterium tuberculosis complex clinical isolates to phagosomal cues encountered inside activated (IFN-gamma+LPS) murine bone marrow-derived macrophages 24hr post-infection. Transcript levels of intracellular mycobacteria were compared to extracellular bacteria of the same strain (An aliquot of the inoculum used to infect macrophages was incubated in the absence of macrophages for 24hr in an identical flask). Set of arrays that are part of repeated experiments Keywords: Biological Replicate Biological Replicate Computed
Project description:This study uses microarray analyses to examine transcriptional responses of Mycobacterium tuberculosis complex clinical isolates to phagosomal cues encountered inside activated (IFN-gamma+LPS) murine bone marrow-derived macrophages 24hr post-infection. Transcript levels of intracellular mycobacteria were compared to extracellular bacteria of the same strain (An aliquot of the inoculum used to infect macrophages was incubated in the absence of macrophages for 24hr in an identical flask). Set of arrays that are part of repeated experiments Keywords: Biological Replicate
Project description:New strategies are required to reduce the worldwide burden of tuberculosis. Intracellular survival and replication of Mycobacterium tuberculosis after macrophage phagocytosis is a fundamental step in the complex host-pathogen interactions that lead to granuloma formation and disease. Greater understanding of how the bacterium survives and thrives in these environments will inform novel drug and vaccine discovery programmes. Here, we use in-depth RNA sequencing of Mycobacterium bovis BCG from human THP-1 macrophages to describe the mycobacterial adaptations to the intracellular environment. We identify 329 significantly differentially regulated genes, highlighting cholesterol catabolism, methyl-citrate cycle and iron homeostasis as important for mycobacteria inside macrophages. Focused analysis of PE/PPE and cytochrome P450 gene families highlight additional pathways that are upregulated (35 and five respectively) 24h after infection. Comparison of the intracellular transcriptome to gene essentiality and immunogenicity studies identified 15 potential targets that are both required for intracellular survival and induced on infection, and eight genes upregulated that have been demonstrated to be immunogenic in TB patients. Further insight into these new and established targets will support drug and vaccine development efforts.
Project description:Following phagocytosis by macrophages, Mycobacterium tuberculosis (Mtb) senses the intracellular environment and remodels its gene expression for growth in the phagosome. Abramovitch et.al. in this current study identified an Acid and Phagosome Regulated (aprABC) locus that is unique to the Mtb complex and whose gene expression is induced during growth in acidic environments in vitro and in macrophages. The authors propose a model where phoP senses the acidic pH of the phagosome and induces aprABC expression to fine-tune processes unique for intracellular adaptation of Mtb complex bacteria. This study uses microarray analyses to compare transcriptional responses of wild type Mycobacterium tuberculosis (CDC1551) to aprABC locus deletion mutants and the phoP transposon mutant. The bacteria were grown to early log phase in vented T-75 standing flasks containing 12 mL of pH 7.0 7H9 OADC medium. Transcript levels of the wild type bacteria were compared to the following mutants: aprABC null, aprBC null, aprC null, phoP::Tn mutant.
Project description:Following phagocytosis by macrophages, Mycobacterium tuberculosis (Mtb) senses the intracellular environment and remodels its gene expression for growth in the phagosome. Abramovitch et.al. in this current study identified an Acid and Phagosome Regulated (aprABC) locus that is unique to the Mtb complex and whose gene expression is induced during growth in acidic environments in vitro and in macrophages. The authors propose a model where phoP senses the acidic pH of the phagosome and induces aprABC expression to fine-tune processes unique for intracellular adaptation of Mtb complex bacteria.
Project description:Mycobacterium tuberculosis thrives within macrophages by residing in phagosomes and preventing them from maturing and fusing with lysosomes. A parallel transcriptional survey of intracellular mycobacteria and their host macrophages revealed signatures of heavy metal poisoning. In particular, mycobacterial genes encoding heavy metal efflux P-type ATPases CtpC, CtpG, and CtpV, and host cell metallothioneins and zinc exporter ZnT1, were induced during infection. Consistent with this pattern of gene modulation, we observed a burst of free zinc inside macrophages, and intraphagosomal zinc accumulation within a few hours postinfection. Zinc exposure led to rapid CtpC induction, and ctpC deficiency caused zinc retention within the mycobacterial cytoplasm, leading to impaired intracellular growth of the bacilli. Thus, the use of P(1)-type ATPases represents a M. tuberculosis strategy to neutralize the toxic effects of zinc in macrophages. We propose that heavy metal toxicity and its counteraction might represent yet another chapter in the host-microbe arms race. [Data is also available from http://bugs.sgul.ac.uk/E-BUGS-122]
