Role of Tet1 and 5-hydroxymethylcytosine in cocaine action (RNA-Seq)
Ontology highlight
ABSTRACT: Here we show that Tet1 is down-regulated in mouse nucleus accumbens (NAc), a key brain reward structure, by repeated cocaine administration which enhances behavioral responses to cocaine. Through genome-wide 5hmC profiling, we identified 5hmC changes selectively clustered in both enhancer and coding regions of genes with several annotated neural functions. By coupling with mRNA sequencing, we found cocaine-induced alterations in 5hmC correlate positively with alternative splicing. We also demonstrated that 5hmC alteration at certain genes lasts up to a month after cocaine exposure. RNA Nac samples were collected at various time points after 7 daily cocaoine ip administration for 5hmC and transcriptome analysis
Project description:Here we show that Tet1 is down-regulated in mouse nucleus accumbens (NAc), a key brain reward structure, by repeated cocaine administration which enhances behavioral responses to cocaine. Through genome-wide 5hmC profiling, we identified 5hmC changes selectively clustered in both enhancer and coding regions of genes with several annotated neural functions. By coupling with mRNA sequencing, we found cocaine-induced alterations in 5hmC correlate positively with alternative splicing. We also demonstrated that 5hmC alteration at certain genes lasts up to a month after cocaine exposure. DNA Nac samples were collected at various time points after 7 daily cocaoine ip administration for 5hmC and transcriptome analysis
Project description:Here we show that Tet1 is down-regulated in mouse nucleus accumbens (NAc), a key brain reward structure, by repeated cocaine administration which enhances behavioral responses to cocaine. Through genome-wide 5hmC profiling, we identified 5hmC changes selectively clustered in both enhancer and coding regions of genes with several annotated neural functions. By coupling with mRNA sequencing, we found cocaine-induced alterations in 5hmC correlate positively with alternative splicing. We also demonstrated that 5hmC alteration at certain genes lasts up to a month after cocaine exposure.
Project description:Here we show that Tet1 is down-regulated in mouse nucleus accumbens (NAc), a key brain reward structure, by repeated cocaine administration which enhances behavioral responses to cocaine. Through genome-wide 5hmC profiling, we identified 5hmC changes selectively clustered in both enhancer and coding regions of genes with several annotated neural functions. By coupling with mRNA sequencing, we found cocaine-induced alterations in 5hmC correlate positively with alternative splicing. We also demonstrated that 5hmC alteration at certain genes lasts up to a month after cocaine exposure.
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:ATP-dependent chromatin remodeling proteins are being implicated increasingly in the regulation of complex behaviors, including models of several psychiatric disorders. Here, we demonstrate that Baz1b, an accessory subunit of the ISWI family of chromatin remodeling complexes, is upregulated in the nucleus accumbens (NAc), a key brain reward region, in both chronic cocaine-treated mice and mice that are resilient to chronic social defeat stress. In contrast, no regulation is seen in mice that are susceptible to this chronic stress. Viral-mediated overexpression of Baz1b, along with its associated subunit Smarca5, in mouse NAc is sufficient to potentiate both rewarding responses to cocaine, including cocaine self-administration, and resilience to chronic social defeat stress. However, despite these similar, proreward behavioral effects, genome-wide mapping of BAZ1B in NAc revealed mostly distinct subsets of genes regulated by these chromatin remodeling proteins after chronic exposure to either cocaine or social stress. Together, these findings suggest important roles for BAZ1B and its associated chromatin remodeling complexes in NAc in the regulation of reward behaviors to distinct emotional stimuli and highlight the stimulus-specific nature of the actions of these regulatory proteins. BAZ1B (WSTF) ChIP-seq of mouse. Cocaine vs Saline, 3 biological replicates. In social defeat model: Normal control vs Susceptible vs Resilient, 3 biological replicates.
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: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:Repeated administration of the psychostimulant cocaine has been shown to produce persistent alterations in genome-wide transcriptional regulatory networks, chromatin remodeling activity and, ultimately, gene expression profiles in the brain’s reward circuitry. Virtually all previous investigations have centered on drug-mediated effects occurring throughout active euchromatic regions of the genome, such that very little is known concerning the impact of cocaine exposure on the regulation and maintenance of heterochromatin in adult brain. Here, we report that cocaine administration dramatically and dynamically alters heterochromatic histone H3 lysine 9 trimethylation (H3K9me3) in the nucleus accumbens (NAc), a key brain reward region. Furthermore, we demonstrate that repeated cocaine exposure induces persistent decreases in heterochromatization in this brain region, suggesting a potential role for heterochromatic regulation in the long-term actions of cocaine. To identify precise genomic loci affected by these alterations, chromatin immunoprecipitation followed by massively parallel DNA sequencing (ChIP-Seq) was performed on NAc. ChIP-Seq analyses confirmed the existence of the H3K9me3 mark mainly within inter-genic regions of the genome and identified specific patterns of cocaine-induced H3K9me3 regulation at repetitive genomic sequences. Cocaine-mediated decreases in H3K9me3 enrichment at specific genomic repeats (e.g., LI repeats) were further confirmed by the increased expression of LINE-1 and IAP retrotransposons in NAc. Such increases likely reflect global patterns of genomic de-stabilization in this brain region following repeated cocaine administration and open the door for future investigations into the epigenetic and genetic basis of drug addiction. Animals received daily i.p. injections of either 'saline' (7 treatments of saline) or 'repeated' cocaine (7 treatments of 20 mg/kg cocaine). 24 hours after the last dose, chromatin immunoprecipitation was performed utilizing previously validated methods. Each experimental condition was performed in either duplicate or triplicate (2 cocaine, 3 saline). Briefly, for each ChIP, bilateral 14-gauge NAc punches (anterior and posterior) were pooled from 5 mice (20 punches). Tissue was lightly fixed to cross-link DNA with associated proteins and the material was further sheared and immunoprecipitated using sheep anti-rabbit magnetic beads conjugated to an antibody that specifically recognizes H3K9me3. Resulting immunoprecipitated DNA and total (input) genomic DNA were prepared for ChIP-sequencing using an Illumina kit according to manufacturer’s instructions. 20 ng of starting material, as determined by PicoGreen concentrations, was used in each case. Briefly, each sample underwent end repair followed by addition of an A base to the 3’ end. Proprietary adapters were then ligated to the ends, followed by size selection on a 3% agarose gel. The range of excision was 175-225 bp. Following DNA clean up, samples were amplified with 21 cycles of PCR. Amplification and size selection were confirmed with a BioAnalyzer. 5 pM concentrations were used to generate clusters for sequencing analysis.
Project description:Substance use disorder (SUD) is a chronic neuropsychiatric condition characterized by long-lasting alterations in the neural circuitry regulating reward and motivation. Substantial work has focused on characterizing the molecular substrates which underlie these persistent changes in neural function and behavior; however, this work has overwhelmingly focused on male subjects, despite mounting clinical and preclinical evidence that females demonstrate dissimilar progression to SUD and responsivity to drugs of abuse, such as cocaine. Here, we show that sex is a critical biological variable that defines drug-induced plasticity in the NAc. Using quantitative mass spectrometry, we assessed the protein expression patterns altered by cocaine self-administration and demonstrate unique molecular profiles between males and females. We show that 1. Cocaine self-administration induces non-overlapping protein expression patterns in males and females and 2. Cocaine specifically acts on baseline sexual dimorphisms to exert these effects. Critically, we find that cocaine administration blunts not only basal sex-differences in the accumbens proteome, but also the pre-existing sex differences in behavior for natural rewards. Together, these data suggest that chronic cocaine is capable of rewriting baseline proteomic function to maintain cocaine-specific behaviors.
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.