The GntR-like protein NorG has been shown to affect Staphylococcus aureus genes involved in the resistance to quinolones and beta-lactams such as those encoding the NorB and AbcA transporters. To identify the target genes regulated by NorG, we carried out transcriptional profiling assays using S. aureus RN6390 and its isogenic norG::cat mutant. Our data showed that NorG positively affected the transcription of global regulators mgrA, arlS, and sarZ. The three putative drug efflux pump genes most positively affected by NorG were the NorB efflux pump (5.1-fold), the MmpL-like protein SACOL2566 (5.2-fold), and the BcrA-like drug transporter SACOL2525 (5.7-fold). The S. aureus predicted MmpL protein showed 53% homology with the MmpL lipid transporter of Mycobacterium tuberculosis, and the putative SACOL2525 protein showed 87% homology with the bacitracin drug transporter BcrA of Staphylococcus hominis. Two pump genes most negatively affected by NorG were NorC (4-fold) and AbcA (6-fold). Other categories of genes such as those participating in amino acid, inorganic ion, or nucleotide transporters and metabolism, were also affected by NorG. Real-time RT-PCR assays for mgrA, arlS, sarZ, norB, norC, abcA, mmpL, and bcrA-like were carried out to verify microarray data and showed the same level of up- or down regulation by NorG. The norG mutant showed a twofold increase in the resistance to norfloxacin and rhodamine, both substrates of the NorC transporter, which is consistent with the resistance phenotype conferred by overexpression of norC on a plasmid. These data indicate that NorG has broad regulatory function in S. aureus.
Transcriptional profiling analysis of the global regulator NorG, a GntR-like protein of Staphylococcus aureus.
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View SamplesS. aureus biofilms are associated with the organism's ability to cause disease. Biofilm associated bacteria must cope with the host's innate immune system.
Global transcriptome analysis of Staphylococcus aureus biofilms in response to innate immune cells.
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View SamplesStaphylococcus aureus is a major human pathogen and resistant to numerous clinically used antibiotics. The first antibiotic developed for S. aureus infections was the nonribosomal petide secondary metabolite penicillin. We discovered cryptic nonribosomal peptide secondary metabolites, the aureusimines, made by S. aureus itself that are not antibiotics, but function as small molecule regulators of virulence factor expression. Using established rules and codes for nonribosomal peptide assembly we predicted these nonribosomal peptides, and used these predictions to identify them from S. aureus culture broths. Functional studies using global microarray and mouse bacteremia models established that the aureusimines control virulence factor expression and are necessary for productive infections. This is the first report of the aureusimines and has important implications for the treatment of drug resistant S. aureus. Targeting aureusimine synthesis may provide novel anti-infectives.
Staphylococcus aureus nonribosomal peptide secondary metabolites regulate virulence.
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View SamplesMore than 200 direct CodY target genes in Staphylococcus aureus were identified by genome-wide analysis of in vitro DNA binding. This analysis, which was confirmed for some genes by DNase I footprinting assays, revealed that CodY is a direct regulator of numerous transcription units associated with amino acid biosynthesis, transport of macromolecules and virulence. The virulence genes regulated by CodY fell into three groups. One group was dependent on the Agr system for its expression; these genes were indirectly regulated by CodY through its repression of the agr locus. A second group was regulated directly by CodY. The third group, which includes genes for alpha-toxin and capsule synthesis, was regulated by CodY in two ways, i.e., by direct repression and by repression of the agr locus. Since S. aureus CodY was activated in vitro by the branched chain amino acids and GTP, CodY appears to link changes in intracellular metabolite pools with the induction of numerous adaptive responses, including virulence.
Direct targets of CodY in Staphylococcus aureus.
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View SamplesThe S. aureus transcriptome was assessed for strains Newman (wild type) and Newman (sarZ) during both exponential (2hr) and early stationary (5hr) cell growth.
A new oxidative sensing and regulation pathway mediated by the MgrA homologue SarZ in Staphylococcus aureus.
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View SamplesThe Staphylococcus aureus two-component regulatory system, SrrAB, coordinates hypoxic responses during in vitro growth conditions.
Bacterial Hypoxic Responses Revealed as Critical Determinants of the Host-Pathogen Outcome by TnSeq Analysis of Staphylococcus aureus Invasive Infection.
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View SamplesOverexpression of a caspase-resistant form of Bcl-2 (D34A) in human umbilical vein endothelial cells (EC) implanted into immunodeficient mice promotes the maturation of human EC-lined microvessels invested by vascular smooth muscle cells (VSMC) of mouse origin. In contrast, EC implants not overexpressing Bcl-2 form only simple, uncoated EC tubes. Here we compare the phenotypes of vessels formed in vivo and the transcriptomes in vitro of EC expressing different forms of Bcl-2. Wild type Bcl-2, like the caspase resistant D34A Bcl-2 mutant, is anti-apoptotic in vitro and promotes VSMC recruitment in vivo, whereas a G145E mutant that has diminished anti-apoptotic activity in vitro does not promote vessel maturation in vivo. The D34A and wild type forms of Bcl-2, but not the G145E mutant form of Bcl-2 significantly regulate RNA transcripts previously associated with EC-VSMC interactions and VSMC biology, including matrix Gla protein, insulin like growth factor binding protein (IGFBP)-2, matrix metaloproteinase-14 (MMP14), ADAM17 and Stanniocalcin-1. These effects of Bcl-2 on the transcriptome are detected in EC cultured as angiogenic 3-D tubes but are attenuated in EC cultured as 2-D monolayers. Bcl-2-regulated transcription in EC may contribute to vascular maturation, and support design of tissue engineering strategies using EC.
Antiapoptotic activities of bcl-2 correlate with vascular maturation and transcriptional modulation of human endothelial cells.
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View SamplesLuteinising hormone (LH) is a key regulator of male fertility through its effects on testosterone secretion by Leydig cells. Mice in which the LH receptor is knocked out (LuRKO) show reduced testicular size, reduced testosterone, elevated serum LH, and a spermatogenic arrest that can be rescued by administration of testosterone. This study examines the onset of spermatogenic arrest in LuRKO males using transcriptional profiling of developing mutant and control testes. We also examine the initial stages of testosterone rescue of the phenotype, in order to identify key upstream regulators of testosterone-dependent spermatogenesis.
Transcriptional profiling of luteinizing hormone receptor-deficient mice before and after testosterone treatment provides insight into the hormonal control of postnatal testicular development and Leydig cell differentiation.
Specimen part
View SamplesMutation or deletion of Neurofibromin (NF1), an inhibitor of RAS signaling, frequently occurs in epithelial ovarian cancer (EOC), supporting therapies that target downstream RAS effectors, such as the RAF-MEK-ERK pathway. However, no comprehensive studies have been carried out testing the efficacy of MEK inhibition in NF1-deficient EOC. Here, we performed a detailed characterization of MEK inhibition in NF1-deficient EOC cell lines using kinome profiling and RNA sequencing. Our studies showed MEK inhibitors were ineffective at providing durable growth inhibition in NF1-deficient cells due to kinome reprogramming. MEKi-mediated destabilization of FOSL1 resulted in induced expression of RTKs and their downstream RAF and PI3K signaling overcoming MEKi therapy. MEKi synthetic enhancement screens identified BRD2 and BRD4 as integral mediators of the MEKi-induced RTK signatures. Inhibition of BET proteins using BET bromodomain inhibitors (BETi) blocked MEKi-induced RTK reprogramming, indicating BRD2 and BRD4 represent promising therapeutic targets in combination with MEKi to block resistance due to kinome reprogramming in NF1-deficient EOC. Overall design: Examination of the global effects on transcription in response to trametinib (GSK212) in A1847 cells.
Intrinsic Resistance to MEK Inhibition through BET Protein-Mediated Kinome Reprogramming in NF1-Deficient Ovarian Cancer.
Specimen part, Cell line, Treatment, Subject
View SamplesGene expression profiles of a single Arabidopsis genotype (Col-0) in response to isogenic Pseudomonas syringae strains expressing one of four different cloned avr genes was studied (avrRpt2, avrRpm1, avrPphB, avrRps4; responses mediated by the R genes RPS2, RPM1, RPS5 and RPS4 ).
Discovery of ADP-ribosylation and other plant defense pathway elements through expression profiling of four different Arabidopsis-Pseudomonas R-avr interactions.
Age, Specimen part, Disease, Disease stage
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