Strand specific sequencing illustrates the complex transcriptional response of Legionella pneumophila during infection
Ontology highlight
ABSTRACT:
ORGANISM(S): Legionella pneumophila
PROVIDER: GSE27232 | GEO | 2011/02/11
SECONDARY ACCESSION(S): PRJNA137479
REPOSITORIES: GEO
Similar Datasets
Project description:Legionella pneumophila is a Gram-negative facultative intracellular human pathogen with a distinct biphasic lifestyle. One of its primary environmental hosts in the free-living amoeba Acanthamoeba castellanii and its infection by L. pneumophila mimics that seen in human macrophages. Here we present analysis of strand specific sequencing of the transcriptional response of L. pneumophila in broth growth and in infection of A. castellanii. Examination of 2 infection and 3 broth growth time points
2011-02-11 | E-GEOD-27232 | biostudies-arrayexpress
Project description:Legionella pneumophila are important opportunistic pathogens for which environmental reservoirs such as protists are crucial for the infection of humans. Free-living amoebae are considered key hosts providing nutrients and shelter for highly efficient intracellular proliferation of L. pneumophila, which eventually leads to lysis of the amoeba host cell. Yet, the significance of other bacterial players for L. pneumophila ecology is poorly understood. In this study we used a ubiquitous amoeba and their bacterial endosymbiont to investigate the impact of this common association on L. pneumophila infection. We demonstrate that Acanthamoeba castellanii harboring the chlamydial symbiont Protochlamydia amoebophila were able to erase L. pneumophila and, in contrast to symbiont-free amoebae, survived the infection and were able to resume growth. Environmental amoeba isolates harboring P. amoebophila were equally well-protected, and fresh environmental isolates of L. pneumophila were equally well-erased, suggesting ecological relevance of this symbiont-mediated protection. We further show that protection was not mediated by impaired L. pneumophila uptake. Instead, we observed reduced virulence of L. pneumophila released from symbiont-containing amoebae that is strongly supported by transcriptome data. Interference with transition to the transmissive phase is thus likely the basis for this protection. Finally, our data indicate that the defensive response of amoebae harboring P. amoebophila leaves the amoebae with superior fitness reminiscent of immunological memory. Given that mutualistic associations between bacteria and amoebae are widely distributed, P. amoebophila and potentially other amoeba endosymbionts could be key elements in shaping environmental survival, abundance and virulence of this important pathogen thereby affecting frequency of human infection.
2019-04-14 | GSE125876 | GEO
Project description:Legionella pneumophila is the causative agent of Legionnaires’ disease, an acute pulmonary infection. L. pneumophila is able to infect and multiply in both phagocytic protozoan, such as Acanthamoeba castellanii, and mammalian professional phagocytes. The best-known virulence determinant used by L. pneumophila to infect host cells is a Type IVb translocation system named Icm/Dot, which is used to modify the host cell functions to the benefit of the bacteria. To date the Icm/Dot systeme is known to translocate more than 100 effectors. While the transcriptional response of Legionella to the intracellular environement of A. castelannii as already been investigated, much less is known of how Legionella reacts transcriptionnally inside human macrophages. In this study, the transcriptome of L. pneumophila was monitored during exponential and post-exponential phase in rich AYE broth and during infection of human cultured macrophages by using microarray and a RNA amplification procedure called SCOTS to allow for the study of conditions of low bacterial loads. Among the genes induced intracellularly are those involved in amino acid synthesis pathway leading to L-arginine, L-histidne and L-proline as well as many transport system involved in amino acid and iron uptake. The Icm/Dot systems is not differentially expressed inside cells compare to the E phase control but the effectors are strongly induced. The intracellular transcriptome was further used to identify putative new Icm/Dot effectors and translocation was show to occur for 3 of them. This study provides a comprehensive view of how L. pneumophila react to the human macrophages intracellular environment.
2011-01-01 | GSE23029 | GEO
Project description:Through RNA-sequencing we compared A. castellanii infected with wild type L. pneumophila to A. castellanii infected with an isogenic dotA mutant strain, which is unable to replicate intracellularly. We identified clear morphological and transcriptional changes in A. castellanii over the course of infection. Genes differentially expressed during infection fell into fundamental biological processes, such as small GTPase signalling, cytoskeleton dynamics, metabolism and cell proliferation. Members of the Sirtuin family of class III histone deacetylases were upregulated by A. castellanii throughout wild type L. pneumophila infection. sir6f expression was important for A. castellanii proliferation during infection and L. pneumophila replication
2020-07-11 | GSE154179 | GEO
Project description:Legionella pneumophila is the causative agent of Legionnaires’ disease, an acute pulmonary infection. L. pneumophila is able to infect and multiply in both phagocytic protozoan, such as Acanthamoeba castellanii, and mammalian professional phagocytes. The best-known virulence determinant used by L. pneumophila to infect host cells is a Type IVb translocation system named Icm/Dot, which is used to modify the host cell functions to the benefit of the bacteria. To date the Icm/Dot systeme is known to translocate more than 100 effectors. While the transcriptional response of Legionella to the intracellular environement of A. castelannii as already been investigated, much less is known of how Legionella reacts transcriptionnally inside human macrophages. In this study, the transcriptome of L. pneumophila was monitored during exponential and post-exponential phase in rich AYE broth and during infection of human cultured macrophages by using microarray and a RNA amplification procedure called SCOTS to allow for the study of conditions of low bacterial loads. Among the genes induced intracellularly are those involved in amino acid synthesis pathway leading to L-arginine, L-histidne and L-proline as well as many transport system involved in amino acid and iron uptake. The Icm/Dot systems is not differentially expressed inside cells compare to the E phase control but the effectors are strongly induced. The intracellular transcriptome was further used to identify putative new Icm/Dot effectors and translocation was show to occur for 3 of them. This study provides a comprehensive view of how L. pneumophila react to the human macrophages intracellular environment. The aim of this work was to study the gene expression profile of Legionella during infection of macrophages infected at a low multiplicity of infection (MOI). SCOTS is a method that allows amplification of small amounts of bacterial RNA from infected host cells, while discarding host cell transcripts and ribosomal RNA. Before infection, macrophages derived from the THP-1 monocyte cell line were pre-treated with antibodies against the L. pneumophila major outer membrane protein, which increases the efficiency of bacterial entry into host cells . After 2 hours of infection, the macrophages were washed and treated with gentamicin for 1 hour, to synchronize the infection and kill extracellular bacteria, and cells were washed 3 times and fresh medium was added. Samples for the first time point (T0) were collected after the gentamicin treatment. Samples were also collected after 6h (T6) and 18h (T18). Samples from all conditions, including growth in AYE broth to exponential (E) or post exponential (PE) phase, were treated with three consecutive rounds of SCOTS and the resulting cDNA was labeled and hybridized to the microarray slides. As a reference channel, labeled gDNA was also hybridized. For each condition studied, three independent biological replicates and two technical replicates were analyzed, resulting in six replicates for each condition. The data was background subtracted and normalized by calculating the contribution of each spot to the total intensity and the ratio to gDNA was recorded. A one tailed student's T test was used for statistical analysis and the ratio between test conditions (PE, T0, T6 and T18) and the control conditions (E phase or T0) was calculated.
2011-01-01 | E-GEOD-23029 | biostudies-arrayexpress
Project description:The social amoeba Dictyostelium discoideum is vulnerable to infection by the pathogen that causes Legionnaire's Disease, Legionella pneumophila. Dictystelium cells lacking the dual-specificity phospahatase DupA are at least partially resistant to infection, and strikingly the expression profile of uninfected dupA null cells mirrors the profile of infected wild-type cells to a considerable extent. This suggests that DupA has a key role in regulating host defence systems.
2009-09-24 | E-TABM-509 | biostudies-arrayexpress
Project description:The bacterium Legionella pneumophila is capable of intracellular replication within freshwater protozoa as well as human alveolar macrophages, the latter of which results in the serious pneumonia Legionnaires’ disease. A primary factor involved in these host cell interactions is the Dot/Icm Type IV secretion system that is responsible for translocating effector proteins needed to establish and maintain the bacterial replicative niche. Several regulatory factors have been identified to control the expression of the Dot/Icm system and effectors, one of which is the CpxRA two-component system, suggesting essentiality for virulence. However, studies elsewhere have shown that L. pneumophila strains harboring mutated cpxRA genes have minimal to no impact on L. pneumophila intracellular growth in protozoa and macrophages. In this study, we generated L. pneumophila cpxR, cpxA, and cpxRA in-frame null mutant strains to further delineate the role of the CpxRA system in bacterial survival and virulence. Surprisingly, we found that cpxR and cpxRA are essential for intracellular replication within Acanthamoeba castellanii, but not in U937 macrophage-like cells. Transcriptome analysis revealed that CpxRA regulates a large number of virulence-associated proteins including a number of Dot/Icm effectors as well as 14 Type II secreted substrates. Furthermore, the cpxR and cpxRA mutants were more sodium resistant than wildtype, and cpxRA expression reaches maximal levels during post-exponential phase. Taken together, our findings suggest the CpxRA system is a key contributor to L. pneumophila virulence via virulence factor regulation.
2016-09-16 | GSE73873 | GEO
Project description:Legionella pneumophila is a Gram-negative, environmental bacterium, which causes the life-threatening pneumonia Legionnaires’ disease. The facultative intracellular bacterium forms biofilms and employs the Icm/Dot type IV secretion system (T4SS) to replicate in amoebae and macrophages. The Legionella quorum sensing (Lqs) system and the transcription factor LvbR form a regulatory network controlling various traits, including bacterial motility, virulence and biofilm architecture. Here we show by comparative proteomics that in biofilms formed by L. pneumophila mutant strains lacking LvbR or the response regulator LqsR, proteins encoded by the 133 kb fitness island and components of the flagellum (FlaA) are downregulated. Confocal microscopy revealed that the ∆lqsR or ∆flaA mutant strains formed biofilms of the same patchy morphology as the parental strain JR32, while the ∆lvbR mutant forms a mat-like biofilm as previously shown. Acanthamoeba castellanii amoebae migrated more slowly through biofilms formed by the ∆lvbR, ∆lqsR or ∆flaA mutant strains, and amoebae migration was impaired in biofilms formed by L. pneumophila lacking a functional Icm/Dot T4SS (∆icmT) or the secreted effector proteins LegG1 and PpgA. Amoebae migrating through biofilms formed by JR32, ∆lvbR or ∆icmT were decorated by clusters of bacteria, while amoebae in ∆lqsR or ∆flaA biofilms were not. Taken together, the Lqs system, LvbR, FlaA and the Icm/Dot T4SS regulate migration of A. castellanii through L. pneumophila biofilms, and – with the exception of the T4SS – also regulate bacterial cluster formation on the amoeba. Hence, amoebae migration through L. pneumophila biofilms is regulated by bacterial quorum sensing, virulence and motility.
2022-06-08 | PXD030337 | Pride
Project description:Legionella pneumophila was exposed for 3h to 160 ug/ml of CuO nanoparticle. Untreated samples are used as the control condition.
2013-03-04 | GSE41966 | GEO
