Project description:Despite addiction being one of the most prevalent and debilitating disorders worldwide, effective treatments are lacking. Repeated cocaine exposure induces maladaptive transcriptional regulation within the brainâ??s reward circuitry, such as the nucleus accumbens (NAc), and epigenetic mechanisms, such as histone acetylation or methylation on Lys (K) residues, have been linked to these lasting actions of cocaine. However, in contrast to K methylation, the functional role of histone Arg (R) methylation remains unexplored in addiction models and poorly understood in brain in general. Here we show that protein-R-methyltransferase-6 (PRMT6) and its associated histone mark, asymmetric dimethylation of R2 on histone H3 (H3R2me2a), are decreased in the NAc of mice and rats after repeated cocaine exposure, as well as in the NAc of cocaine-addicted humans. PRMT6 downregulation occurs selectively in NAc medium spiny neurons expressing dopamine D2 receptors (D2-MSNs) and serves to protect against cocaine-induced addictive-like behavioral abnormalities. Using ChIP-seq, we demonstrate that reduced H3R2me2a binding at gene targets in NAc after repeated cocaine is strongly correlated with increased binding of H3K4me3, and identify Src kinase signaling inhibitor 1 (Srcin1 or p140Cap) as a key gene for these chromatin modifications. Cocaine induction of Srcin1 in NAc, which is associated with reduced Src signaling, decreases cocaine reward, the motivation to self administer cocaine, and cocaine-induced changes in NAc MSN dendritic spines. These results suggest that this suppression of Src signaling in NAc D2-MSNs, via PRMT6 and H3R2me2a downregulation, functions as a homeostatic brake to restrain cocaine action, and provide novel candidates for the development of new treatments for cocaine addiction. H3R2me2A ChIP-seq of mouse. Cocaine vs Saline, 3 biological replicates.
Project description:Despite addiction being one of the most prevalent and debilitating disorders worldwide, effective treatments are lacking. Repeated cocaine exposure induces maladaptive transcriptional regulation within the brain’s reward circuitry, such as the nucleus accumbens (NAc), and epigenetic mechanisms, such as histone acetylation or methylation on Lys (K) residues, have been linked to these lasting actions of cocaine. However, in contrast to K methylation, the functional role of histone Arg (R) methylation remains unexplored in addiction models and poorly understood in brain in general. Here we show that protein-R-methyltransferase-6 (PRMT6) and its associated histone mark, asymmetric dimethylation of R2 on histone H3 (H3R2me2a), are decreased in the NAc of mice and rats after repeated cocaine exposure, as well as in the NAc of cocaine-addicted humans. PRMT6 downregulation occurs selectively in NAc medium spiny neurons expressing dopamine D2 receptors (D2-MSNs) and serves to protect against cocaine-induced addictive-like behavioral abnormalities. Using ChIP-seq, we demonstrate that reduced H3R2me2a binding at gene targets in NAc after repeated cocaine is strongly correlated with increased binding of H3K4me3, and identify Src kinase signaling inhibitor 1 (Srcin1 or p140Cap) as a key gene for these chromatin modifications. Cocaine induction of Srcin1 in NAc, which is associated with reduced Src signaling, decreases cocaine reward, the motivation to self administer cocaine, and cocaine-induced changes in NAc MSN dendritic spines. These results suggest that this suppression of Src signaling in NAc D2-MSNs, via PRMT6 and H3R2me2a downregulation, functions as a homeostatic brake to restrain cocaine action, and provide novel candidates for the development of new treatments for cocaine addiction.
Project description:Increasing evidence supports a role for altered gene expression in mediating the lasting effects of cocaine on the brain, and recent work has demonstrated the involvement of chromatin modifications in these alterations. However, all such studies to date have been restricted by their reliance on microarray technologies which have intrinsic limitations. Here, we used advanced sequencing methods, RNA-seq and ChIP-seq, to obtain an unprecedented view of cocaine-induced changes in gene expression and associated adaptations in numerous modes of chromatin regulation in the nucleus accumbens, a key brain reward region. We identify unique combinations of chromatin changes, or signatures, that accompany cocaine’s regulation of gene expression, including the dramatic involvement of pre-mRNA alternative splicing in cocaine action. Together, this delineation of the cocaine-induced epigenome in the nucleus accumbens reveals several novel modes of drug regulation, thereby providing new insight into the biological basis of cocaine addiction. More broadly, the combinatorial chromatin and transcriptional approaches that we describe serve as an important resource for the field, as they can be applied to other systems to reveal novel transcriptional and epigenetic mechanisms of neuronal regulation. ChIP-seq of 6 marks (H3K27me3, H3K36me3, H3K4me1, H3K4me3, H3K9me2, RNApolII) were done on mouse nucleus accumbens 24 hr after 7 day daily cocaine ip injection with saline as control. Three replicates for each condition.
Project description:Increasing evidence supports a role for altered gene expression in mediating the lasting effects of cocaine on the brain, and recent work has demonstrated the involvement of chromatin modifications in these alterations. However, all such studies to date have been restricted by their reliance on microarray technologies which have intrinsic limitations. Here, we used advanced sequencing methods, RNA-seq and ChIP-seq, to obtain an unprecedented view of cocaine-induced changes in gene expression and associated adaptations in numerous modes of chromatin regulation in the nucleus accumbens, a key brain reward region. We identify unique combinations of chromatin changes, or signatures, that accompany cocaineM-bM-^@M-^Ys regulation of gene expression, including the dramatic involvement of pre-mRNA alternative splicing in cocaine action. Together, this delineation of the cocaine-induced epigenome in the nucleus accumbens reveals several novel modes of drug regulation, thereby providing new insight into the biological basis of cocaine addiction. More broadly, the combinatorial chromatin and transcriptional approaches that we describe serve as an important resource for the field, as they can be applied to other systems to reveal novel transcriptional and epigenetic mechanisms of neuronal regulation. Total RNA was isolated from mouse nucleus accumbens 24 hr after 7 day daily cocaine or saline control ip injection for mRNA sequencing by following illumina RNA seq kit protocol. Another batch of acute cocaine RNA-seq was performed using the same parameters except the treatment group was given 6 days of saline injection followed by 1 day of cocaine injection. The acute cocaine batch serves as control experiments.
Project description:DNA methylation profiling of nucleus Accumbens of rats that self administered cocaine, were subjected to 30 withdrawal days, were treated with aCSF, RG108 or SAM and were subjected to extinction tests. The groups consist of: 1. Rats that self-administered cocaine for 10 days and that were subjected to a withdrawal period of 30 days, were injected in the nucleus accumbens with aCSF and were subjected to an extinction test for assessment of cue-induced cocaine-seeking behavior (aCSF) 2. Rats that self-administered cocaine for 10 days and that were subjected to a withdrawal period of 30 days, were injected in the nucleus accumbens with RG108 and were subjected to an extinction test for assessment of cue-induced cocaine-seeking behavior (RG108) 3. Rats that self-administered cocaine for 10 days and that were subjected to a withdrawal period of 30 days, were injected in the nucleus accumbens with SAM and were subjected to an extinction test for assessment of cue-induced cocaine-seeking behavior (SAM)
Project description:We cataloged miRNA expression in the nucleus accumbens and at striatal synapses in control and chronically cocaine-treated mice. We identified cocaine-responsive miRNAs, synaptically-enriched and depleted miRNA families, and confirmed cocaine-induced changes in protein expression for several predicted synaptic target genes. Analysis of small RNA from Mus musculus nucleus accumbens (NAc) and postsynaptic densities (PSD) with and without chronic cocaine treatment.
Project description:Many of the long-term effects of cocaine on the brain's reward circuitry have been shown to be mediated by alterations in gene expression. Several chromatin modifications, including histone acetylation and methylation, have been implicated in this regulation, but the effect of other histone modifications remains poorly understood. Poly(ADP-ribose) polymerase-1 (PARP-1), a ubiquitous and abundant nuclear protein, catalyzes the synthesis of a negatively charged polymer called poly(ADP-ribose) or PAR on histones and other substrate proteins and forms transcriptional regulatory complexes with several other chromatin proteins. Here, we identify an essential role for PARP-1 in cocaine-induced molecular, neural, and behavioral plasticity. Repeated cocaine administration, including self-administration, increased global levels of PARP-1 and its mark PAR in mouse nucleus accumbens (NAc), a key brain reward region. Using PARP-1 inhibitors and viral-mediated gene transfer, we established that PARP-1induction in NAc mediates enhanced behavioral responses to cocaine, including increased self-administration of the drug. Using chromatin immunoprecipitation sequencing, we demonstrated a global, genome-wide enrichment of PARP-1 in NAc of cocaine-exposed mice and identified several PARP-1 target genes that could contribute to the lasting effects of cocaine. Specifically, we identified sidekick-1-important for synaptic connections during development-as a critical PARP-1 target gene involved in cocaine's behavioral effects as well as in its ability to induce dendritic spines on NAc neurons. These findings establish the involvement of PARP-1 and PARylation in the long-term actions of cocaine. c57bl/6 mice were given IP injections of chronic cocaine 20mg/kg once per day for 7 days and sacrificed 30 minutes after the final dose of cocaine. Control animals were given saline for 7 days and sacrificed 30 minutes after the final dose of saline. Nucleus accumbens (NAc) tissue was collected and then PARP-1 ChIP-seq was performed. Three sequencing replicates were performed on each group.
Project description:Genetic association studies, pharmacological investigations and analysis of mice-lacking individual genes have made it clear that Cocaine administration and Withdrawal have a profound impact on multiple neurotransmitter systems. The GABAergic medium spiny neurons of the nucleus accumbens (NAc) exhibit changes in the expression of genes encoding receptors for glutamate and in the signaling pathways triggered by dopamine binding to G-protein-coupled dopamine receptors. Deep sequence analysis provides a sensitive, quantitative and global analysis of the effects of Cocaine on the NAc transcriptome. RNA prepared from the NAc of adult male mice receiving daily injections of Saline or Cocaine, or Cocaine followed by a period of Withdrawal, was used for high-throughput sequence analysis. Changes were validated by quantitative polymerase chain reaction or Western blot. On the basis of pathway analysis, a preponderance of the genes affected by Cocaine and Withdrawal was involved in the cadherin, heterotrimeric G-protein and Wnt signaling pathways. Distinct subsets of cadherins and protocadherins exhibited a sustained increase or decrease in expression. Sustained down-regulation of several heterotrimeric G-protein β- and γ-subunits was observed. In addition to altered expression of receptors for small molecule neurotransmitters, neuropeptides and endocannabinoids, changes in the expression of plasma membrane transporters and vesicular neurotransmitter transporters were also observed. The effects of chronic Cocaine and Withdrawal on the expression of genes essential to cholinergic, glutamatergic, GABAergic, peptidergic and endocannabinoid signaling are as profound as their effects on dopaminergic transmission. Simultaneous targeting of multiple Withdrawal-specific changes in gene expression may facilitate development of new therapeutic approaches that are better able to prevent relapse. High-throughput sequence analysis of RNA prepared from the nucleus accumbens of adult male mice receiving daily injections of Saline or Cocaine, or Cocaine followed by a period of Withdrawal. Nucleus accumbens libraries were sequenced in nine lanes (three technical replicates per sample) on an Illumina GAIIx using a 37-cycle paired-end sequencing protocol. Replicates were analyzed for intra-sample disparity and read data from all three lanes were then merged into one composite data file per sample; intra-sample coefficient of determination, R2 ≥ 0.98. The composite file was used for subsequent analyses.
Project description:Gene expression profiling in dopaminergic brain structures of rats self-administering cocaine. Effect of histone deacetylase inhibition We have shown that injection of the HDAC inhibitor trichostatin A (TsA) to rats is sufficient to decrease their motivation to self-administer cocaine. The aim of the present study was to investigate alterations in gene expression patterns in the Anterior Cingulate Cortex and Nucleus Accumbens of rats self-administering cocaine and treated repeatedly with TsA, and compare them with rats taking only cocaine. We used Affymetrix microarrays to identify genes the expression of which was up-regulated or downregulated during this process. Drug self-administration was performed in dark operant chambers under a fixed-ratio 1 schedule of reinforcement that was carried out for 4 days during daily 2 h sessions. Each nosepoke into the active hole triggered the i.v. delivery of a 40 μl cocaine solution (0,3 mg/kg/injection) under the control of the computer. Rats were sacrificed 2 h after the 4th self-administration session; the anterior cingulate cortex and the nucleus accumbens were then dissected. Two treatments comparison
Project description:Changes in gene expression contribute to the long-lasting regulation of the brain's reward circuitry seen in drug addiction, however, the specific genes regulated and the transcriptional mechanisms underlying such regulation remain poorly understood. Here, we used chromatin immunoprecipitation coupled with promoter microarray analysis to characterize genome-wide epigenetic changes in the mouse nucleus accumbens, a crucial brain reward region, after repeated cocaine administration. Our findings reveal several interesting principles of gene regulation by cocaine and of the role of Î?FosB and CREB, two prominent cocaine-induced transcription factors, in this brain region. Mice were treated with cocaine or saline. Chromatin immunoprecipitation was performed for acetylated histone H3 and H4 as described previously (Kumar et al., 2005) with minor modifications. Immunoprecipitated DNA was amplified via ligation-mediated PCR and hybridized to Nimblgen mouse MM5 promoter arrays. 2 biological replicates per condition.