Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Transcription profiling of S. cerevisiae (budding yeast) mutants reveals Isc1p plays a key role in hydrogen peroxide resistance and chronological lifespan through modulation of iron levels and programmed cell death

ABSTRACT: Changes in the transcriptome of Isc1p deficient mutants. The inositolphosphosphingolipid phospholipase C (Isc1p) of Saccharomyces cerevisiae belongs to the family of neutral sphingomyelinases that generates the bioactive sphingolipid ceramide. In this work the role of Isc1p in oxidative stress resistance and chronological lifespan was investigated. Loss of Isc1p resulted in a higher sensitivity to hydrogen peroxide that was associated with an increase in oxidative stress markers, namely intracellular oxidation, protein carbonylation and lipid peroxidation. Microarray analysis showed that Isc1p deficiency upregulated the iron regulon leading to increased levels of iron, which is known to catalyze the production of the highly reactive hydroxyl radicals via the Fenton reaction. In agreement, iron chelation suppressed hydrogen peroxide sensitivity of isc1D mutants. Cells lacking Isc1p also displayed a shortened chronological lifespan associated with oxidative stress markers and ageing of parental cells was correlated with a decrease in Isc1p activity. The analysis of DNA fragmentation and caspase activity showed that Isc1p deficiency increased apoptotic programmed cell death associated with oxidative stress and ageing. Furthermore, deletion of Yca1p metacaspase suppressed the oxidative stress sensitivity and premature ageing phenotypes of isc1D mutants. These results indicate that Isc1p plays an important role in the regulation of cellular redox homeostasis, through modulation of iron levels, and of apoptosis.

INSTRUMENT(S): Scanning hardware

ORGANISM(S): Saccharomyces cerevisiae

SUBMITTER: Vitor Costa

PROVIDER: E-MEXP-1136 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Isc1p plays a key role in hydrogen peroxide resistance and chronological lifespan through modulation of iron levels and apoptosis.

Almeida Teresa T Marques Marta M Mojzita Dominik D Amorim Maria A MA Silva Rui D RD Almeida Bruno B Rodrigues Pedro P Ludovico Paula P Hohmann Stefan S Moradas-Ferreira Pedro P Côrte-Real Manuela M Costa Vítor V

Molecular biology of the cell 20071227 3

The inositolphosphosphingolipid phospholipase C (Isc1p) of Saccharomyces cerevisiae belongs to the family of neutral sphingomyelinases that generates the bioactive sphingolipid ceramide. In this work the role of Isc1p in oxidative stress resistance and chronological lifespan was investigated. Loss of Isc1p resulted in a higher sensitivity to hydrogen peroxide that was associated with an increase in oxidative stress markers, namely intracellular oxidation, protein carbonylation, and lipid peroxid ...[more]

PMID: 18162582

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Project description:Escherichia coli O157 presents a number of specific problems in terms of food safety and public health. It has been found that E. coli O157 is more resistant to a number of the stresses encountered during food production such as heat, pH and osmotic shock. This greater resistance is thought to contribute to the low infectious dose of E. coli O157 (<100 organisms). Moreover, E. coli O157 is associated with debilitating conditions such as haemorrhagic colitis and haemoytic uraemic syndrome, particularly in children and the elderly. We have been studying the stress responses of E. coli O157:H7 (Sakai) and comparing with a commensal strain of E. coli K-12, MG1655. We found that E. coli O157 (Sakai) is more sensitive to oxidative stress than MG1655. A microarray study of these strains treated with sub-lethal concentrations (0.5mg/ml) of menadione revealed big differences in their responses. In E. coli O157 (Sakai), 540 genes responded significantly to the treatment compared to 121 genes in MG1655. One surprising finding from the microarray data was the observation that many iron-transport genes were up-regulated in E. coli O157 (Sakai) whereas relatively few were induced in MG1655 despite the fact that the bacteria were grown in a medium containing ample iron. We speculated that the induction of iron transport genes in an iron-rich medium might have contributed to the enhanced killing of E. coli O157 (Sakai) through triggering of a Fenton reaction. We speculated that the difference in sensitivity to oxidative stress might be due to differences in the intracellular iron content of E. coli O157 and MG1655. We found that E. coli O157 contains ~50% more iron than MG1655 and believe that during oxidative stress, this iron is released by damaged proteins. The greater levels of free iron in E. coli O157 will trigger a greater Fenton reaction that can damage the ferric uptake regulator (Fur), resulting in unregulated iron transport. In MG1655, the lower iron content results in a smaller Fenton reaction, enabling the cellular protection systems to limit damage and protect Fur. Overnight cultures of E. coli O157 (Sakai) and E. coli K-12 MG1655 were grown in Neidhardt's EZ Rich Defined Medium and diluted 1:100 in 50 ml fresh medium in 125 ml Ehrlenmeyer flasks. The cultures were shaken at 37C until the optical density (OD600) reached 0.4. Each culture was divided into 2 equal parts in identical flasks. One flask contained menadione bisulphite to a final concentration of 0.5 mg/ml; the other flask contained an equivalent volume of distilled water. The flasks were shaken for a further 10 mins and then treated with RNAprotect™ to stabilise the mRNA. The experiment was performed 3 times on different days. Six custom-made microarray slides were used in this study; each slide was hybridised with labelled cDNA made from mRNA taken from untreated and treated E. coli O157 (Sakai) or MG1655.

Dataset Information

Transcription profiling of S. cerevisiae (budding yeast) mutants reveals Isc1p plays a key role in hydrogen peroxide resistance and chronological lifespan through modulation of iron levels and programmed cell death

Publications

Isc1p plays a key role in hydrogen peroxide resistance and chronological lifespan through modulation of iron levels and apoptosis.

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