Project description:Arrays comparing Pseudomonas aeruginosa growth in a defined synthetic cystic fibrosis sputum medium with and without aromatic amino acids. Additional arrays comparing wild-type Pseudomonas aeruginosa and phhR mutant P. aeruginosa in defined synthetic cystic fibrosis sputum medium.
Project description:Pseudomonas aeruginosa airway infection is the primary cause of death in Cystic Fibrosis (CF). During early infection P. aeruginosa produces multiple virulence factors, which cause acute pulmonary disease and are largely regulated by quorum sensing (QS) intercellular signalling networks. Longitudinal clinical studies have observed the loss, through adaptive mutation, of QS and QS-related virulence in late chronic infection. Although the mechanisms are not understood, infection with QS mutants has been linked to a worse outcome for CF patients. By comparing QS-active and QS-inactive P. aeruginosa CF isolates, we have identified novel virulence factors and pathways associated with QS disruption. In particular, we noted factors implicating increased intra-phagocyte survival. Our data present novel targets as candidates for future CF therapies. Some of these targets are already the subject of drug development programmes for the treatment of other bacterial pathogens and may provide cross-over benefit to the CF population. Refer to individual Series. This SuperSeries is composed of the following subset Series: GSE25128: Gene expression data from Pseudomonas aeruginosa strains isolated from cystic fibrosis lung infections GSE25129: Comparative genomic hybridisation data from Pseudomonas aeruginosa strains isolated from cystic fibrosis lung infections
Project description:Pseudomonas aeruginosa undergoes genetic change during chronic infection of the airways of cystic fibrosis (CF) patients. One common change is mutation of lasR. LasR is a transcriptional regulator that responds to one of the quorum sensing signals in P. aeruginosa, and regulates acute virulence factor expression as well as central metabolic functions. P. aeruginosa mutants in which lasR was inactivated emerged in the airways of CF patients early during chronic infection, and during growth in the laboratory on Luria-Bertani agar. Both environments are rich in amino acids. Inactivation of lasR in these isolates conferred a growth advantage with amino acids, a phenotype that could account for selection of lasR mutants both in vivo and in vitro. P. aeruginosa lasR mutants were identified by their distinctive colony morphology, including autolysis that correlated with an imbalance in 4-hydroxy-2-alkylquinolines (HAQs), and an iridescent metallic sheen likely caused by the accumulation of one such HAQ. The alterations in transcriptional profile due to inactivation of lasR were conserved in isolates from multiple young CF patients. P. aeruginosa lasR mutations may represent surrogate markers to delineate stages in the natural history of CF airway disease, each with different prognostic and therapeutic implications, analogous to the markers used to direct cancer treatment. Similar to cancer cell mutations that promote unrestricted growth, lasR mutations may promote unrestricted growth of P. aeruginosa in the CF airway by enabling more efficient utilization of available amino acids. Analyse the effects of mutation of the lasR gene in Pseudomonas aeruginosa isolates from cystic fibrosis patients by comparing the transcriptional profile of an isolate from a young patient with that of an isogenic engineered lasR mutant.
Project description:At mid-log phase (OD600 of 0.5), unique gene expression patterns were observed between these two strains with 3.4% of the transcripts (188/5570) expressed differentially. Of the 188 significantly varied (>1.8 fold) genes, 115 were up-regulated in 383 while 73 were up-regulated in 2192. Experiment Overall Design: The goal of this experiment was to identify the differentially expressed genes from two genetically similar but phenotypically distinct P. aeruginosa strains 383 and 2192. Two strains were isolated two days apart from the sputum of the same cystic fibrosis patient. Following proper culture RNA was extracted from the two strains. Affymetrix GeneChip Pseudomonas aeruginosa was used to examine the gene expression paterns of the two strains.
