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Title: Proteasome inhibition and oxidative biochemistry are synergistic triggers of metabolic heme toxicity (part 2)      
dateReleased:
08-21-2016
description:
Control of intracellular heme levels by extracellular scavenger proteins and intracellular heme oxygenases are essential functions during disease states with enhanced extracellular heme release. During severe hemolysis or rhabdomyolysis uncontrolled heme exposure can cause acute kidney injury and endothelial damage. The cytotoxic activity of heme has been primarily attributed to its pro-oxidative potential. However, the mechanisms of heme toxicity have never been systematically explored. Besides its redox reactivity, heme could also adversely alter cellular functions through its broad binding affinity to multiple non-hemoproteins. Such interactions may impair protein functions and support heme toxicity. In this study we mapped the gene expression profile of Hb triggered acute kidney injury in old blood transfused guinea pigs by serial analysis of gene expression (SAGE). Additionally, the toxic heme response of mouse embryo fibroblasts was systematically characterized on the gene and protein expression levels by gene array experiments and quantitative mass-spectrometry of stable isotope labeled cells. In all these studies, in addition to oxidative stress signals, the most significant signals were reproducibly found for biologic networks related to altered protein degradation, which ultimately triggers the response to unfolded proteins and apoptosis. These screening data could be mechanistically explained by heme-proteasome interactions and a proteasome inhibitor activity of heme. Proteasome inhibition drastically reduced the threshold of cellular toxicity during heme exposure. We therefore propose a novel model of heme toxicity whereby proteasome inhibition by the porphyrin fuels a vicious cycle of oxidative protein modification, accumulation of damaged proteins, cell damage and apoptosis. A two color common reference design was chosen with 2-8 independent biological replicates of each condition. Each experimental sample (Cy5 labeled) was hybridized against a non-treated reference sample (Cy3 labeled). To compensate for dye bias control arrays with competitively hybridized Cy3- and Cy5-labeled non-treated reference samples were used. The latter allowed for a very robust statistical analysis with pair-wise comparison of treatment array replicates versus the corresponding control array replicates.
privacy:
not applicable
aggregation:
instance of dataset
ID:
E-GEOD-50146
refinement:
raw
alternateIdentifiers:
50146
keywords:
functional genomics
dateModified:
09-12-2016
availability:
available
types:
gene expression
name:
Mus musculus
ID:
A-GEOD-10333
name:
Agilent-026655 Whole Mouse Genome Microarray 4x44K v2 (Feature Number version)
accessURL: https://www.ebi.ac.uk/arrayexpress/files/E-GEOD-50146/E-GEOD-50146.raw.1.zip
storedIn:
ArrayExpress
qualifier:
gzip compressed
format:
TXT
accessType:
download
authentication:
none
authorization:
none
accessURL: https://www.ebi.ac.uk/arrayexpress/files/E-GEOD-50146/E-GEOD-50146.processed.1.zip
storedIn:
ArrayExpress
qualifier:
gzip compressed
format:
TXT
accessType:
download
authentication:
none
authorization:
none
accessURL: https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE50146
storedIn:
Gene Expression Omnibus
qualifier:
not compressed
format:
HTML
accessType:
landing page
primary:
true
authentication:
none
authorization:
none
abbreviation:
EBI
homePage: http://www.ebi.ac.uk/
ID:
SCR:004727
name:
European Bioinformatics Institute
homePage: https://www.ebi.ac.uk/arrayexpress/
ID:
SCR:002964
name:
ArrayExpress

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