Mycobacterium bovis transcriptional response to nitric oxide
Ontology highlight
ABSTRACT: We used microarray hybridization to analyze the expression pattern of M. bovis after exposure to nitric oxide. In M. tuberculosis, this treatment has been shown to induce a response similar to the hypoxic stress. Results showed the up-regulation of 51 genes belonging to the DosR regulon. The most remarkable difference with M. tuberculosis was the lack of expression of narX and narK2 in M. bovis, both genes related to survival during hypoxic stress. We further confirm this by qRT-PCR and also explore differential activity at promoter level.
Project description:We used microarray hybridization to analyze the expression pattern of M. bovis after exposure to nitric oxide. In M. tuberculosis, this treatment has been shown to induce a response similar to the hypoxic stress. Results showed the up-regulation of 51 genes belonging to the DosR regulon. The most remarkable difference with M. tuberculosis was the lack of expression of narX and narK2 in M. bovis, both genes related to survival during hypoxic stress. We further confirm this by qRT-PCR and also explore differential activity at promoter level. Four independent biological replicates were analyzed for each condition, and two dye-swap experiments were included.
Project description:In this report we demonstrated that under aerobic conditions, Mycobacterium bovis BCG expressing an hsp60-driven second copy of the hypoxia-related transcriptional regulator DosR increased 2-fold or greater the expression of 38 out of the 48 genes belonging to the DosR regulon, including the latency antigens Rv1733c, Rv2029, Rv2627, and Rv2628. Expression of DosR under these conditions slightly delayed in vitro growth, but did not promote a non-replicating state as opposed to microaerobic and hypoxic adaptation. Our results suggest BCG producing DosR can be cultured under standard in vitro conditions, allowing evaluation of this strain as a latency-specific vaccine candidate.
Project description:Rationale: Tuberculosis has a devastating impact on global health by claiming nearly 1.4 million lives each year. During infection Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis, produces heterogenous populations some of which don’t produce colonies on agar but grow in liquid media and often require supplementation with culture supernatants or recombinant Resuscitation-promoting factor, thus defined as differentially culturable bacilli. Objectives: to evaluate whether exposure to nitric oxide (NO), a well-known host defence molecule, alters mycobacterial growth phenotypes and drives generation of Rpf-dependent differentially culturable bacilli. Methods: a novel NO donor was synthesised and tested against Mtb and Mycobacterium bovis BCG in vitro, followed by growth assays, flow cytometry analysis and assessment of transcriptomic responses. Resuscitation-promoting factor (Rpf) inhibitors were used to characterise the role of Rpf proteins in the reactivation of NO-treated mycobacteria. Mycobacterial phenotypes were also investigated during infection of THP-1 macrophages activated with retinoic acid and vitamin D3. Measurements and Main Results: differentially culturable mycobacteria were generated after exposure to the novel NO donor or during infection of activated THP-1 cells. Resuscitation of these differentially culturable bacilli was largely abolished by specific Rpf inhibitors. Transcriptomic analysis revealed redox-associated stress signatures mediated by SigH and SigF, with significant down-regulation of ribosome and cell wall architecture genes, including rpfA, rpfB and rpfE, and induction of genes involved in response to thiol stress, sulphur metabolism and iron acquisition. Conclusion: Our study provides mechanistic insights into the generation of Rpf-dependent Mtb during tuberculosis and outlines a critical role of NO in this process.
Project description:In this report we demonstrated that under aerobic conditions, Mycobacterium bovis BCG expressing an hsp60-driven second copy of the hypoxia-related transcriptional regulator DosR increased 2-fold or greater the expression of 38 out of the 48 genes belonging to the DosR regulon, including the latency antigens Rv1733c, Rv2029, Rv2627, and Rv2628. Expression of DosR under these conditions slightly delayed in vitro growth, but did not promote a non-replicating state as opposed to microaerobic and hypoxic adaptation. Our results suggest BCG producing DosR can be cultured under standard in vitro conditions, allowing evaluation of this strain as a latency-specific vaccine candidate. Set of arrays that are part of repeated experiments
Project description:To study the entire transcriptional and translational M. tuberculosis response from initial survival to eventual escape from nitric oxide (NO) stress, we exposed exponentially growing M. tuberculosis to 1 mM diethylenetriamine/nitric oxide (DETA/NO) and followed the adaptive response over 48 hours. Samples were obtained from two independent experiments performed in triplicate and we sampled aliquots for transcriptome profiling by RNA sequencing at 20 min, 2 h and 24 h and for mass spectrometry-based shotgun proteomics at 20 min, 40 min, 1 h, 2 h, 4 h, 8 h, 12 h, 24 h and 48 h post NO exposure.
Project description:The purpose of this study was to understand the impact of prrA overexpression on global M. tuberculosis transcriptional response to nitric oxide.
Project description:Mycobacterium tuberculosis is an intracellular human pathogen with the ability to resist and adapt to many adverse conditions it encounters upon infection. Among these, overcoming the production of nitric oxide by macrophages could be key for M. tuberculosis success. We have challenged M. tuberculosis with a sub-lethal concentration of nitric oxide and followed the transcriptomic response through RNA-seq for 48 hours.
Project description:Mycobacterium tuberculosis is the causative agent of tuberculosis, a disease that affects one-third of the world’s population. The sole extant vaccine for tuberculosis is the live attenuated Mycobacterium bovis bacille Calmette-Guerin (BCG). We examined 13 representative BCG strains from around the world to ascertain their ability to express DosR-regulated dormancy antigens. These are known to be recognized by T-cells of M. tuberculosis infected individuals, especially those harboring latent infections. Differences in expression of these antigens could be valuable for use as diagnostic markers to distinguish BCG vaccination from latent tuberculosis. We determined that all BCG strains were defective for induction of two dormancy genes, narK2 (Rv1737c) and narX (Rv1736c). NarK2 is known to be necessary for nitrate respiration during anaerobic dormancy. Analysis of the narK2/X promoter region revealed a base substitution mutation in all tested BCG strains and M. bovis in comparison to the M. tuberculosis sequence. We also show that nitrate reduction by BCG strains during dormancy was greatly reduced compared to M. tuberculosis and varied between tested strains. Several dormancy regulon transcriptional differences were also identified among the strains, as well as variation in their growth and survival. These findings demonstrate defects in DosR regulon expression during dormancy and phenotypic variation between commonly used BCG vaccine strains. 12 different BCG strains were examined as well as M. tuberculosis H37Rv and M. bovis. Two arrays per strain were analyzed, one with the addition of nitric oxide and the other utilizing hypoxia treatment, both conditions shown to induce expression of the dormancy regulon. The reference sample for each array was log phase M. tuberculosis H37Rv.
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 purpose of this study is to comprehensively elucidate the role of nitric oxide and nitric oxide synthase isoforms in pulmonary emphysema using cap analysis of gene expression (CAGE) sequencing.