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Nucleosome Repositioning: Nicotine- and Cocaine-induced Changes

ABSTRACT: SH-SY5Y, neuroblastoma cells, were exposed to nicotine for 10, 60, and 90 minutes or cocaine for 5, 20, 40, and 60 minutes. Drugs of abuse modify behavior by altering gene expression in the brain. Gene expression can be regulated by changes in DNA methylation as well as by histone modifications, which alter chromatin structure, DNA compaction and DNA accessibility. In order to better understand the molecular mechanisms directing drug-induced changes in chromatin structure, we examined DNA-nucleosome interactions within promoter regions of 858 genes in human neuroblastoma cells (SH-SY5Y) exposed to nicotine or cocaine. Widespread, drug- and time-resolved repositioning of nucleosomes was identified at the transcription start site and promoter region of multiple genes. Nicotine and cocaine produced unique and shared changes in terms of the numbers and types of genes affected, as well as repositioning of nucleosomes at sites which could increase or decrease the probability of gene expression based on DNA accessibility. Half of the drug-induced nucleosome positions approximated a theoretical model of nucleosome occupancy based on physical and chemical characteristics of the DNA sequence, whereas the basal or drug-naive positions were generally DNA sequence independent. Thus we suggest that nucleosome repositioning represents an initial dynamic genome-wide alteration of the transcriptional landscape preceding more selective downstream transcriptional reprogramming, which ultimately characterizes the cell- and tissue-specific responses to drugs of abuse.

ORGANISM(S): Homo sapiens

PROVIDER: GSE71795 | GEO | 2015/08/07

SECONDARY ACCESSION(S): PRJNA292096

REPOSITORIES: GEO

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Project description:In summary, we characterized genomic signatures of response to drugs of abuse and we found positive correlations between the drug-induced expression and various behavioral effects. These signatures are formed by two dynamically inducible transcriptional networks: (1) CREB/SRF-dependent gene pattern that appears to be related to drug-induced neuronal activity, (2) the pattern of genes controlled at least in part via release of glucocorticoids and androgens that are associated with rewarding and harmful drug effects. The discovery of co-expressed networks of genes allowed for the identification of master-switch controlling factors involved in molecular response to the drugs. Finally, using the pharmacological tools we were able to dissect and inhibit particular gene expression patterns from genomic profile. Type: Drug response, Time-course, Gene expression profiling with Illumina Microarrays Keywords: Addiction, Drugs of abuse, Time-course, Immediate Early Genes, Glucocorticoid receptor dependent genes, Cocaine, Heroin, Nicotine, Ethanol, Morphine, Methamphetamine The microarray experiment was performed to analyze time-course of drug-induced transcriptional response in C57BL/6J mouse striatum. Six the most addictive and harming drugs of abuse (morphine 20 mg/kg, heroin 10 mg/kg, ethanol 2 g/kg, nicotine 1 mg/kg, methamphetamine 2 mg/kg or cocaine 25 mg/kg, i.p.) were selected for the comparison. Drug doses were previously reported as rewarding in mice and further tested in our laboratory. To analyze dynamics of early, intermediate and relatively late changes of mRNA abundance the experiment was performed in four time points (1, 2, 4 and 8h after drug administration). To exclude influence of drug injection and circadian rhythm on gene expression profile, control groups of saline treated and naïve animals were prepared for each time point. Design of the experiment assumed pooling of two animals per each array and using of three independent arrays per group. To provide appropriate balance in the whole dataset groups were equally divided between the array hybridization batches. 'Complete' normalized data and non-normalized data (containing control rows not represented in Platform GPL6105) are linked below as supplementary files.

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Nucleosome Repositioning: Nicotine- and Cocaine-induced Changes

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