Project description:Mycobacterium tuberculosis, the causative agent of tuberculosis accounts for 1.5 million annual deaths worldwide. The two well-characterized strains of the parental H37 strain namely, H37Ra and H37Rv show different pathogenic phenotypes. In order to identify factors that are responsible for virulence, we compared the proteome and the phosphoproteome profiles of virulent (H37Rv) and virulence attenuated (H37Ra) strains of M. tuberculosis. Quantitative proteomic analysis resulted in the identification and quantitation of 2,709 proteins and 505 phosphosites. Comparative analysis revealed over 5-fold overexpression of several proteins associated with virulence. Our data indicates that there are definable molecular differences between H37Rv and H37Ra strains at both the proteome and phosphoproteome levels which may explain the virulence and phenotypic differences.
Project description:Host macrophage transcriptional responses to intracellular pathogens remain poorly characterized. We screened transcriptional enhancers engaged in response to M. tuberculosis (Mtb) infection by ChIPseq analysis of histone H3 lysine 4 monomethylation (H3K4me1). De novo monomethylation during infection was associated with genes implicated in host defense and apoptosis. These regions were enriched for binding sites for ETS transcription factor family members and response elements for nuclear receptors, including liver X receptors (LXRs) and peroxisomal proliferator activated receptors (PPARs), many of which were encompassed by transposable elements. LXRa expression was strongly induced by infection, whereas that of PPARs was unaffected. LXR DNA binding and NCoR corepressor recruitment increased proportionately in infected cells but coactivator association was unchanged, consistent with a lack of induction of endogenous agonists. However, treatment of infected cells with LXR agonist T0901317 strongly increased coactivator recruitment and induced a gene expression program characterized by enhanced innate immune signaling and lipid metabolism. Remarkably, T0901317 treatment selectively induced apoptosis in infected macrophages, and was accompanied by Mtb death, reducing mycobacterial burden 18-fold relative to vehicle 5d after infection. These studies define macrophage transcriptional responses to Mtb infection, and suggest that tissue-specific LXRa agonists may be efficacious in clinical management of tuberculosis.
Project description:Human peripheral blood mononuclear cells were cultured in presence of H37Ra strain at 37oC, 5%CO2. Cellular aggregates were collected at 24h, and RNA extracted and hybridized to Affymetrix microarrays (HG-U133). Raw data from microarray experiments was analyzed with dCHIP and SAM programs to determine the significance of changes at the biological context.
Project description:Human peripheral blood mononuclear cells were cultured in presence of H37Ra strain at 37oC, 5%CO2. Cellular aggregates were collected at 24h, and RNA extracted and hybridized to Affymetrix microarrays (HG-U133). Raw data from microarray experiments was analyzed with dCHIP and SAM programs to determine the significance of changes at the biological context. PBMCs were exposed in triplicate to H37Ra strain. PBMCs from the same donor were cultured in triplicate at the same conditions than treated samples. RNA was extracted from each sample and hybridized to Affymetrix Human arrays.
Project description:The result validated the connections between mutations, gene expression and mycobacterial pathogenicity, and identified new possible virulence-associated pathways in M. tuberculosis.
Project description:M. tuberculosis H37Ra, an avirulent tubercle bacillus, is a commonly used model to investigate virulence attenuation in M. tuberculosis. Comparative high-throughput studies have earlier correlated its avirulence to the presence of specific mutations or absence of certain proteins. However, a recent sequencing study of H37Ra has disproved several genomic differences earlier reported to be associated with virulence. This warrants further investigations on the H37Ra proteome as well. In this study, we carried out an integrated analysis of the genome, transcriptome and proteome of H37Ra. In addition to confirming single nucleotide variations and insertion-deletions that were reported earlier, our study provides novel insights into the mutation spectrum in the promoter regions of 7 genes. In all, we provide protein coding evidence for 3,199 proteins representing ~79% of the total predicted gene count. Transcriptome analysis revealed the expression of 3,945 high-confidence transcripts including several transcripts mapping to the genome that were previously thought to be non-coding. We identified 9 genes whose coding potential was hitherto reported to be absent in H37Ra . These include 2 putative virulence factors belonging to ESAT-6 like family of proteins. Furthermore, proteogenomic analysis enabled us to identify 63 novel proteins coding genes and correct 25 existing gene models in H37Ra genome. A majority of these were found to be conserved in the virulent strain H37Rv as well as in other mycobacterial sp. suggesting that that the differences in the virulent and avirulent strains of M. tuberculosis are not entirely dependent on the expression of certain proteins or their absence but may possibly be ascertained to functional changes.
Project description:In this study, RNA sequencing (Transcriptome sequencing) was employed to investigate the global transcriptome changes in the macrophages during the different strains of M.tb infection. THP-1 cells derived macrophages were exposed to the virulent M.tb strain H37Rv (Rv) or the avirulent M.tb strain H37Ra (Ra), and the M.tb BCG vaccine strain was used as a control. The cDNA libraries were prepared from M.tb infected macrophages and then sequenced.
Project description:Mycobacterium tuberculosis relies on the ESX-1 secretion system for survival, multiplication in and escape from macrophages. In this work we investigate the role of the EspB protein, encoded within the esx-1 gene cluster, in virulence and ESX-1 substrate secretion in M. tuberculosis H37Rv. Genetic, proteomic and immunological data show that, contrary to previous reports, an espB knock-out mutant is only partially attenuated in ex vivo infection models, where EsxA, EsxB and EspC antigen presentation is not affected, and secretes the major virulence factor EsxA. Additionally, we demonstrate that EspB does not require an intact and functional ESX-1 apparatus for being secreted in H37Rv and in M. bovis BCG, as opposed to other strains such as CDC1551 and Erdman, thereby suggesting that other ESX systems may be involved in the process. Overall our findings highlight unexplored differences in the secretion profiles of various mycobacterial strains and underscore the plasticity of ESX-dependent secretion in mycobacteria.
Project description:In this study we compared the transcriptome of bovine macrophages infected with two Mycobacterium bovis strains of variable virulence, co-cultured with autologous lymphocytes. We used the highly virulent M. bovis strain called Mb04-303 and the attenuated Mb534 strain. We first observed that only the infection of bovine macrophages with the virulent strain, Mb04-303, induced in peripheral bovine mononuclear cells a powerful innate immune response capable of controlling the intracellular mycobacterial replication.By RNAseq analysis we found that infections with Mb04-303 downregulated the KEAP1-NFE2L2 pathway that encodes a transcriptional factor involved in antioxidant genes and inflammasome activation and upregulated the type 1 interferon signalling pathway, compared to the infections with the attenuated Mb534 strain. T