Project description:The present study reports the gene expression data of Mycobacterium tuberculosis H37Rv and H37RvΔdosSΔdosT (DKO) grown on 0.2 % acetate/glucose under aerobic/hypoxic conditions. Acetate was reported to be present in granulomas of Mycobacterium tuberculosis infected guinea pigs which are also hypoxic. By exposing Mycobacterium tuberculosis H37Rv and H37RvΔdosSΔdosT to different combinations of granulomatous stresses (acetate/glucose and aerobic/hypoxic conditions) alongwith other experimental data, we were able to delineate a new signaling pathway that activates DevR (DosR) regulon through Acetyl phosphate. The presence of two pathways highlights the importance of targeting DevR and not DevS/DosT for intercepting DevRST signalling cascade.
Project description:This SuperSeries is composed of the following subset Series: GSE36341: mRNA degradation in Mycobacterium tuberculosis under aerobic conditions GSE36342: mRNA degradation in Mycobacterium smegmatis under aerobic conditions GSE36343: mRNA degradation in Mycobacterium tuberculosis during cold and hypoxic stress GSE36344: mRNA degradation in Mycobacterium tuberculosis with DosR ectopically induced Refer to individual Series
Project description:The innate mechanisms used by Mycobacterium tuberculosis to persist during periods of non-proliferation are central to understanding the physiology of the bacilli during latent disease. We have used whole genome expression profiling to expose adaptive mechanisms initiated by M. tuberculosis in two common models of M. tuberculosis non-proliferation. The first of these models was a standard growth curve in which gene expression changes were followed from exponential growth through the transition to stationary phase. In the second model, we followed the adaptive process of M. tuberculosis during transition from aerobic growth to a state of anaerobic non-replicating persistence. The most striking finding from these experiments was the strong induction of the entire DosR "dormancy" regulon over approximately 20 days during the long transition to an anaerobic state. This is contrasted by the muted overall response to aerated stationary phase with only a partial dormancy regulon response. From the results presented here we conclude that the respiration-limited environment of the oxygen-depleted NRP model recreates at least one fundamental factor for which the genome of M. tuberculosis encodes a decisive adaptive program.
Project description:The innate mechanisms used by Mycobacterium tuberculosis to persist during periods of non-proliferation are central to understanding the physiology of the bacilli during latent disease. We have used whole genome expression profiling to expose adaptive mechanisms initiated by M. tuberculosis in two common models of M. tuberculosis non-proliferation. The first of these models was a standard growth curve in which gene expression changes were followed from exponential growth through the transition to stationary phase. In the second model, we followed the adaptive process of M. tuberculosis during transition from aerobic growth to a state of anaerobic non-replicating persistence. The most striking finding from these experiments was the strong induction of the entire DosR dormancy regulon over approximately 20 days during the long transition to an anaerobic state. This is contrasted by the muted overall response to aerated stationary phase with only a partial dormancy regulon response. From the results presented here we conclude that the respiration-limited environment of the oxygen-depleted NRP model recreates at least one fundamental factor for which the genome of M. tuberculosis encodes a decisive adaptive program. Keywords: comparative genome hybridization design and stimulus or stress design
Project description:In Mycobacterium tuberculosis, the sensor kinases DosT and DosS activate the transcriptional regulator DosR, resulting in the induction of the DosR regulon, important for anaerobic survival and perhaps latent infection. The individual and collective roles of these sensors has been postulated biochemically, but their roles have remained unclear in vivo. This work demonstrates distinct and additive roles for each sensor during anaerobic dormancy. Both sensors are necessary for wild type levels of DosR regulon induction, and concomitantly, full induction of the regulon is required for wild type anaerobic survival. In the anaerobic model, DosT plays an early role, responding to hypoxia. DosT then induces the regulon and with it DosS, which sustains and further induces the regulon. DosT then loses its functionality as oxygen becomes limited, and DosS alone maintains induction of the genes from that point forward. Thus, M. tuberculosis has evolved a system whereby it responds to hypoxic conditions in a stepwise fashion as it enters an anaerobic state.
Project description:Transcriptional profiling of H37Rv (WT), Mut1 and Comp1 bacteria under aerobic (Aer/0 day, i.e 0 D) and hypoxic conditions (Hyp/5 days standing culture, i.e 5 D). Mut1: H37Rv carrying devR gene disruption by in frame insertion of kanamycin resistance cassette and expressing DevRN-Kan fusion protein. Comp1: Mut1 complemented with low copy number plasmid carrying devR gene expressed from its native constitutive upstream promoter. (Reference: Majumdar et al., 2010, PLoS One 5:e9448). Goal is to compare transcriptional patterns of WT, Mut1 and Comp1 strains under aerobic (0 D) and hypoxic (5 D) conditions in vitro. Two color and One-color experiments,Organism: Mycobacterium tuberculosis, Genotypic Technology designed Custom Mycobacterium tuberculosis H37Rv Whole Genome 8x15k GE Microarray (AMADID-020181)
Project description:Background: Conflicting results have been reported about the role of the two-component sensor and transcriptional regulator DosS/DosR, controlling the expression of the dormancy DosR regulon, for in vivo virulence of M. tuberculosis. Here, we have used a new approach to further analyze the relevance of the dosRS system, by driving DosR (Rv3133c) expression under the control of a constitutive promoter (phsp60). Methodology/Principal Findings: M. tuberculosis H37Rv constitutively expressing the transcriptional regulator DosR (Mtb::DosR) was compared to wild type M. tuberculosis (Mtb+/+) for in vitro growth kinetics and expression of the target genes of the DosR dormancy regulon, for in vivo virulence and for immunogenicity in mice. Under aerobic conditions, hsp60-driven DosR induced the expression of 28 out of 39 tested DosR regulon genes. In vitro growth characteristics were comparable for both strains, but Mtb::DosR showed an attenuated in vivo phenotype in immunocompetent mice, as indicated by reduced bacterial replication, reduced pulmonary immunopathology, reduced cachexia and significantly prolonged survival time as compared Mtb+/+. In immunodeficient SCID mice, Mtb::DosR was fully virulent. RT-qPCR analysis revealed a strong and comparable pulmonary TNF-?? and IL-23 expression following intratracheal infection, whereas IL-12 and IL-17 expression was slightly higher with wild type Mtb+/+. Finally, mice persistently infected with Mtb::DosR for 8 months showed five to tenfold higher lung IFN-?? responses against ten of the 48 DosR regulon encoded antigens (Rv1733c, Rv1734, Rv1738, Rv1996, Rv1997, Rv2029c, Rv2623, Rv2627c, Rv2628 and Rv3127) than mice actively infected with Mtb+/+. In spleen however, DosR regulon encoded antigen specific IFN-?? responses were similar in both groups. Conclusions/Significance. Collectively, these results suggest that increased DosR regulon encoded antigen specific pulmonary T cell responses are responsible for the attenuated phenotype of Mtb::DosR and that infection with Mtb::DosR could be used as a new animal model for studying key aspects of latent tuberculosis.