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GSE35371
Escherichia coli str. k-12 substr. mg1655
58 Downloadable Samples
Affymetrix E. coli Genome 2.0 Array (ecoli2)
Description
The widespread use of electricity raises the question of whether or not 50 Hz (power line frequency in Europe) magnetic fields (MFs) affect organisms. We investigated the transcription of Escherichia coli K-12 MG1655 in response to extremely low-frequency (ELF) MFs. Fields generated by three signal types (sinusoidal continuous, sinusoidal intermittent, and power line intermittent; all at 50 Hz, 1 mT), were applied and gene expression was monitored at the transcript level using an Affymetrix whole-genome microarray. Bacterial cells were grown continuously in a chemostat (dilution rate D = 0.4 h-1) fed with glucose-limited minimal medium and exposed to 50 Hz MFs with a homogenous flux density of 1 mT. For all three types of MFs investigated, neither bacterial growth (determined using optical density) nor culturable counts were affected. Likewise, no statistically significant change (fold-change > 2, P 0.01) in the expression of 4,358 genes and 714 intergenic regions represented on the gene chip was detected after MF exposure for 2.5 h (1.4 generations) or 15 h (8.7 generations). Moreover, short-term exposure (8 min) to the sinusoidal continuous and power line intermittent signal neither affected bacterial growth nor showed evidence for reliable changes in transcription. In conclusion, our experiments did not indicate that the different tested MFs (50 Hz, 1 mT) affected the transcription of E. coli.
Publication Title
Genome-wide transcription analysis of Escherichia coli in response to extremely low-frequency magnetic fields.
Sample Metadata Fields
Treatment
View Samples- Homo sapiens
- 117 Downloadable Samples
- Affymetrix Human Genome U133 Plus 2.0 Array (hgu133plus2)
Description
Apo2L/TRAIL stimulates cancer-cell death through the proapoptotic receptors DR4 and DR5, but the determinants of tumor susceptibility to this ligand are not fully defined. mRNA expression of the peptidyl O-glycosyl transferase GALNT14 correlated with Apo2L/TRAIL sensitivity in pancreatic carcinoma, non-small cell lung carcinoma and melanoma cell lines (P < 0.00009; n=83), and up to 30% of samples from various human malignancies displayed GALNT14 overexpression. RNA interference of GALNT14 reduced cellular Apo2L/TRAIL sensitivity, whereas overexpression increased responsiveness. Biochemical analysis of DR5 identified several ectodomain O-GalNAc-Gal-Sialic acid structures. Sequence comparison predicted conserved extracellular DR4 and DR5 O-glycosylation sites; progressive mutation of the DR5 sites attenuated apoptosis signaling. O-glycosylation promoted ligand-stimulated clustering of DR4 and DR5, which mediated recruitment and activation of the apoptosis-initiating protease caspase-8. These results uncover a novel link between death receptor O-glycosylation and apoptosis signaling, providing potential predictive biomarkers for Apo2L/TRAIL-based cancer therapy.
Publication Title
Death-receptor O-glycosylation controls tumor-cell sensitivity to the proapoptotic ligand Apo2L/TRAIL.
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