The Ataxia telangiectasia Gene Product Is Required for Oxidative Stress-induced G 1 and G 2 Checkpoint Function in Human Fibroblasts

Ataxia telangiectasia (AT) is an autosomal recessive disorder characterized by neuronal degeneration accompanied by ataxia, telangiectasias, acute cancer predisposition, and sensitivity to ionizing radiation (IR). Cells from individuals with AT show unusual sensitivity to IR, severely attenuated cell cycle checkpoint functions, and poor p53 induction in response to IR compared with normal human fibroblasts (NHFs). The gene mutated in AT (ATM) has been cloned, and its product, pATM, has IR-inducible kinase activity. The AT phenotype has been suggested to be a consequence, at least in part, of an inability to respond appropriately to oxidative damage. To test this hypothesis, we examined the ability of NHFs and AT dermal fibroblasts to respond to t-butyl hydroperoxide and IR treatment. AT fibroblasts exhibit, in comparison to NHFs, increased sensitivity to the toxicity of t-butyl hydroperoxide, as measured by colony-forming efficiency assays. Unlike NHFs, AT fibroblasts fail to show G(1) and G(2) phase checkpoint functions or to induce p53 in response to t-butyl hydroperoxide. Treatment of NHFs with t-butyl hydroperoxide activates pATM-associated kinase activity. Our results indicate that pATM is involved in responding to certain aspects of oxidative damage and in signaling this information to downstream effectors of the cell cycle checkpoint functions. Our data further suggest that some of the pathologies seen in AT could arise as a consequence of an inability to respond normally to oxidative damage

Gene expression response in target organ and whole blood varies as a function of target organ injury phenotype

Histopathology, clinical chemistry, hematology and gene expression data were collected from the rat liver and blood after treatment with eight known hepatotoxins

Acetaminophen dosing of humans results in blood transcriptome and metabolome changes consistent with impaired oxidative phosphorylation

The diagnosis and management of drug-induced liver injury (DILI) is hindered by the limited utility of traditional clinical chemistries. It has recently been shown that hepatotoxicants can produce compound-specific changes in the peripheral blood (PB) transcriptome in rodents, suggesting the blood transcriptome might provide new biomarkers of DILI. To investigate in humans, we used DNA microarrays as well as serum metabolomic methods to characterize changes in the transcriptome and metabolome in serial PB samples obtained from 6 healthy adults treated with a 4 g bolus dose of acetaminophen (APAP) and from 3 receiving placebo. Treatment did not cause liver injury as assessed by traditional liver chemistries. However, 48 hours after exposure, treated subjects showed marked down-regulation of genes involved in oxidative phosphorylation/mitochondrial function that was not observed in the placebos (p <1.66E-19). The magnitude of down-regulation was positively correlated with the percent of APAP converted to the reactive metabolite NAPQI (r = 0.739; p=0.058). In addition, unbiased analysis of the serum metabolome revealed an increase in serum lactate from 24 to 72 hours post dosing in the treated subjects alone (p<0.005). Similar PB transcriptome changes were observed in human overdose patients and rats receiving toxic doses

Hierarchical clustering of animals in the low dose/6 hour group using SVM-derived classifiers

Two-way hierarchical clustering using Ward's minimum variance as the heuristic criteria and Euclidean distance as the similarity metric was performed on all of the animals in the low dose/6 hour group using the blood expression values for the 160 transcripts identified as compound classifiers for this dose/time group by a SVM algorithm. The degree of relatedness between each sample is represented by the dendrogram (hierarchical tree) presented in this figure, wherein the height of each branch represents the distance between the two objects being connected.<p><b>Copyright information:</b></p><p>Taken from "Gene expression response in target organ and whole blood varies as a function of target organ injury phenotype"</p><p>http://genomebiology.com/2008/9/6/R100</p><p>Genome Biology 2008;9(6):R100-R100.</p><p>Published online 20 Jun 2008</p><p>PMCID:PMC2481421.</p><p></p

Hierarchical clustering of animals in the medium dose/6 hour group using SVM-derived classifiers

Two-way hierarchical clustering using Ward's minimum variance as the heuristic criteria and Euclidean distance as the similarity metric was performed on all of the animals in the medium dose/6 hour group using the liver expression values for the 160 transcripts identified as compound classifiers for this dose/time group by a SVM algorithm. The degree of relatedness between each sample is represented by the dendrogram (hierarchical tree) presented in this figure, wherein the height of each branch represents the distance between the two objects being connected.<p><b>Copyright information:</b></p><p>Taken from "Gene expression response in target organ and whole blood varies as a function of target organ injury phenotype"</p><p>http://genomebiology.com/2008/9/6/R100</p><p>Genome Biology 2008;9(6):R100-R100.</p><p>Published online 20 Jun 2008</p><p>PMCID:PMC2481421.</p><p></p

PCA of transcripts identified as differentially expressed across the 'Response to hepatocellular injury' category in blood

Blood expression data from the 30 transcripts identified as differentially expressed across the Response to hepatocellular injury category from all 318 treated rats were subjected to PCA. The first principal component is represented by the x-axis, while the second principal component is represented by the y-axis. Each individual animal is represented as a circle and the relationship between the color of the circle and the categorical scores for the Response to hepatocellular injury is illustrated in the key.<p><b>Copyright information:</b></p><p>Taken from "Gene expression response in target organ and whole blood varies as a function of target organ injury phenotype"</p><p>http://genomebiology.com/2008/9/6/R100</p><p>Genome Biology 2008;9(6):R100-R100.</p><p>Published online 20 Jun 2008</p><p>PMCID:PMC2481421.</p><p></p