An RNA-recognition motif protein from Helicobacter pylori binds single-stranded RNAs and stabilizes a pathogenicity island-encoded small RNA
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ABSTRACT:
ORGANISM(S): Helicobacter pylori
PROVIDER: GSE63834 | GEO | 2020/11/25
REPOSITORIES: GEO
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Project description:In this study several putative targets of the RRM protein RbpH (HP0827/HPG27_786) were identified. RNA binding targets of RbpH in two strains of H. pylori (G27 and 26695) were identified using RIP-seq.
2020-11-25 | GSE63833 | GEO
Project description:In this study several putative targets of the RRM protein RbpH (HPG27_786) were identified. Potential targets of RbpH in H. pylori (G27) were identified using total RNA-seq.
2020-11-25 | GSE63832 | GEO
Project description:Helicobacter pylori is a very successful human-specific bacterium worldwide. Infections of the stomach with this pathogen can induce pathologies, including chronic gastritis, peptic ulcers and even gastric cancer. Highly virulent H. pylori strains encode the cytotoxin-associated gene (cag)-pathogenicity island, which expresses a type IV secretion system (T4SS). This T4SS forms a syringe-like pilus structure for the injection of virulence factors such as the CagA effector protein into host target cells. This is achieved by a number of T4SS proteins, including CagI, CagL, CagY and CagA, which by itself binds the host cell integrin member ?(1) followed by delivery of CagA across the host cell membrane. A role of CagA interaction with phosphatidylserine has also been shown to be important for the injection process. After delivery, CagA becomes phosphorylated by oncogenic tyrosine kinases and mimics a host cell factor for the activation or inactivation of some specific intracellular signalling pathways. We review recent progress aiming to characterize the CagA-dependent and CagA-independent signalling capabilities of the T4SS, which include the induction of membrane dynamics, disruption of cell-cell junctions and actin-cytoskeletal rearrangements, as well as pro-inflammatory, cell cycle-related and anti-apoptotic transcriptional responses. The contribution of these signalling pathways to pathogenesis during H. pylori infections is discussed.
| S-EPMC3070773 | biostudies-literature
Project description:Many Gram-negative pathogens harbor type IV secretion systems (T4SS) that translocate bacterial virulence factors into host cells to hijack cellular processes. The pathology of the gastric pathogen Helicobacter pylori strongly depends on a T4SS encoded by the cag pathogenicity island. This T4SS forms a needle-like pilus, and its assembly is accomplished by multiple protein-protein interactions and various pilus-associated factors that bind to integrins followed by delivery of the CagA oncoprotein into gastric epithelial cells. Recent studies revealed the crystal structures of six T4SS proteins and pilus formation is modulated by iron and zinc availability. All these T4SS interactions are crucial for deregulating host signaling events and disease progression. New developments in T4SS functions and their importance for pathogenesis are discussed.
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Project description:BACKGROUND:cag pathogenicity island (PAI) is reported to be a major virulence factor of Helicobacter pylori. AIM:To characterise cagA and the cag PAI in Japanese H pylori strains. METHODS:H pylori isolates from Japanese patients were evaluated for CagA by immunoblot, for cagA transcription by northern blot, and for cagA and 13 other cag PAI genes by Southern blot. cagA negative strains from Western countries were also studied. Induction of interleukin-8 secretion from gastric epithelial cells was also investigated. RESULTS:All Japanese strains retained cagA. Fifty nine of 63 (94%) strains had all the cag PAI genes. In the remaining four, cag PAI was partially deleted, lacking cagA transcripts and not producing CagA protein. Details of the PAI of these strains were checked; three lacked cagB to cagQ (cagI) and continuously cagS to cag13 (cagII), and the remaining one lacked cagB to cag8. Western cagA negative strains completely lacked cag PAI including cagA. Nucleotide sequence analysis in one strain in which the cag PAI was partially deleted showed that the partial deletion contained 25 kb of cag PAI and the cagA promoter. Interleukin-8 induction was lower with the cag PAI partial deletion strains than with the intact ones. All Japanese cag PAI deleted strains were derived from patients with non-ulcer dyspepsia, whereas 41 of 59 (70%) CagA-producing strains were from patients with peptic ulcers or gastric cancer (p<0.05). CONCLUSIONS:Most Japanese H pylori strains had the intact cag PAI. However, some lacked most of the cag PAI in spite of the presence of cagA. Thus the presence of the cagA gene is not an invariable marker of cag PAI related virulence in Japanese strains.
| S-EPMC1727424 | biostudies-literature
Project description:TC1: gastric epithelial (AGS) cells infected with wild type H. pylori (G27) and isogenic mutants in cagA and vacA for 0, 0.5, 3, 6, and 12 hours. Total RNA was used to make single stranded Cy5 labelled probe and compared to Cy3 labelled probe from uninfected AGS cells. Hybridizations of G27 (trial 4) and cagA- (trial 3) timecourses were done in parallel. A technical replicate of the G27 time course (trial 5) and hybridization of vacA- (trial 3) time course were done in parallel. The cagA 6 and 12 hour time points were technically replicated (trial 4) (the cagA 6 hour sample of trial 3 was lost). TC2: Biological replication and expansion of TC1, using more isogenic mutants and timepoints. AGS cells were mock infected, infected with G27, and isogenic mutants in cagN, cagA, cagE, and a deletion of the cag PAI for 0. 1, 3, 6, 12, and 24 hours. Probe synthesis and hybridization was done as in TC1. Note: there may have been a sample mix-up with PAI 12, swapping it with G27 or cagN 12. Groups of assays that are related as part of a time series. Keywords: time_series_design
2005-11-04 | GSE3556 | GEO
Project description:Helicobacter pylori infects over half the world's population and causes a wide range of diseases, including gastritis, peptic ulcer, and two forms of gastric cancer. H. pylori infection elicits a variety of phenotypic responses in cultured gastric epithelial cells, including the expression of proinflammatory genes and changes in the actin cytoskeleton. Both of these responses are mediated by the type IV secretion system (TFSS) encoded by the cag pathogenicity island (cag PAI). We used human cDNA microarrays to examine the temporal transcriptional profiles of gastric AGS cells infected with H. pylori strain G27 and a panel of isogenic mutants to dissect the contributions of various genes in the cag PAI. Infection with G27 induced expression of genes involved in the innate immune response, cell shape regulation, and signal transduction. A mutant lacking the cagA gene, which encodes an effector molecule secreted by the TFSS and required for the host cell cytoskeletal response, induced the expression of fewer cytoskeletal genes. A mutant lacking cagE, which encodes a structural component of the TFSS, failed to up-regulate a superset of host genes, including the cagA-dependent genes, and many of the immune response genes. A mutant lacking the entire cag PAI failed to induce both the cagE-dependent genes and several transiently expressed cagE independent genes. Host cell transcriptional profiling of infection with isogenic strains offered a detailed molecular picture of H. pylori infection and provided insight into potential targets of individual virulence determinants such as tyrosine kinase and Rho GTPase signaling molecules.
| S-EPMC137556 | biostudies-literature
Project description:The Helicobacter pyloricag pathogenicity island (cag PAI) encodes a type IV secretion system that is more commonly found in strains isolated from patients with gastroduodenal disease than from those with asymptomatic gastritis. Genome-wide organization of the transcriptional units in H. pylori strain 26695 was recently established using RNA sequence analysis (Sharma et al., 2010). Here we used quantitative reverse-transcription polymerase chain reaction of open reading frames and intergenic regions to identify putative cag PAI operons in H. pylori; these operons were analyzed further by transcript profiling after deletion of selected promoter regions. Additionally, we used a promoter-trap system to identify functional cag PAI promoters. The results demonstrated that expression of genes on the H. pyloricag PAI varies by nearly five orders of magnitude and that the organization of cag PAI genes into transcriptional units is conserved among several H. pylori strains, including, 26695, J99, G27, and J166. We found evidence for 20 transcripts within the cag PAI, many of which likely overlap. Our data suggests that there are at least 11 operons: cag1-4, cag3-4, cag10-9, cag8-7, cag6-5, cag11-12, cag16-17, cag19-18, cag21-20, cag23-22, and cag25-24, as well as five monocistronic genes (cag4, cag13, cag14, cag15, and cag26). Additionally, the location of four of our functionally identified promoters suggests they are directing expression of, in one case, a truncated version of cag26 and in the other three, transcripts that are antisense to cag7, cag17, and cag23. We verified expression of two of these antisense transcripts, those antisense to cag17 and cag23, by reverse-transcription polymerase chain reaction. Taken together, our results suggest that the cag PAI transcriptional profile is generally conserved among H. pylori strains, 26695, J99, G27, and J166, and is likely complex.
| S-EPMC3417554 | biostudies-literature
Project description:Several genes including the cagA in the cag pathogenicity island (cag PAI) of Helicobacter pylori are thought to be associated with the gastroduodenal diseases and hence variation in the genetic structure of the cag PAI might be responsible for different clinical outcomes. Our study was undertaken to characterize the cag PAI of H. pylori strains from duodenal ulcer (DU) patients and asymptomatic or non-ulcer dyspepsia (NUD/AV) subjects from Kolkata, India. Strains isolated from 52 individuals (30DU and 22NUD/AV) were analyzed by PCR using 83 different primers for the entire cag PAI and also by dot-blot hybridization. Unlike H. pylori strains isolated from other parts of India, 82.6% of the strains used in this study had intact cag PAI, 9.6% had partially deleted cag PAI, and 7.7% of the strains lacked the entire cag PAI. Dot-blot hybridization yielded positive signals in 100% and 93.8% of PCR-negative strains for HP0522-523 and HP0532-HP0534 genes, respectively. An intact cagA promoter region was also detected in all cagA-positive strains. Furthermore, the expression of cagA mRNA was confirmed by RT-PCR for the representative strains from both DU and NUD/AV subjects indicating the active cagA promoter regions of these strains. A total of 66.7% of Kolkata strains produced a ?390-bp shorter amplicon than the standard strain 26695 for the HP0527 gene, homologue of virB10. However, sequence analyses confirmed that the deletion did not alter the reading frame of the gene, and mRNA transcripts were detected by RT-PCR analysis. The strains isolated from DU and NUD/AV express CagA protein and possess a functional type IV secretion system, as revealed by Western blot analyses. Interestingly, no significant differences in cag PAI genetic structure were found between DU and NUD/AV individuals suggesting that other bacterial virulence factors, host susceptibility, and environmental determinants also influence the disease outcome at least in certain geographical locations.
| S-EPMC3062673 | biostudies-literature
Project description:The severity of Helicobacter pylori-related disease is correlated with the presence of a cag pathogenicity island (PAI). Genetic diversity within the cag PAI may have a modifying effect on the pathogenic potential of the infecting strain. We analyzed the complete cag PAI sequences of 11 representative Japanese strains according to their vacA genotypes and clinical effects and examined the relationship between the diversity of the cag PAI and clinical features. The cag PAI genes were divided into two major groups, a Western and a Japanese group, by phylogenetic analysis based on the entire cag PAI sequences. The predominant Japanese strains formed a Japanese cluster which was different from the cluster formed by Western strains. The diversity of the cag PAI was associated with the vacA and cagA genotypes. All strains with the s1c vacA genotype were in the Japanese cluster. In addition, all strains with the East Asian-type cagA genotype were also in the Japanese cluster. Patients infected with the Japanese-cluster strain had high-grade gastric mucosal atrophy. These results suggest that a distinct diversity of the cag PAI of H. pylori is present among Japanese strains and that this diversity may be involved in the development of atrophic gastritis and may increase the risk for gastric cancer.
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