Project description:Neuronal alternative splicing is a key gene regulatory mechanism in brain. Yet the spliceosome machinery is insufficient to fully specify splicing complexity. In considering the role of the epigenome in activity-dependent alternative splicing, we and others find the histone modification, H3K36me3, to be a putative splicing regulator. In the current study, we found that mouse cocaine self-administration caused widespread differential alternative splicing, concomitant with enrichment of H3K36me3 at differentially spliced junctions. Importantly, only targeted epigenetic editing can distinguish between a direct role of H3K36me3 in splicing and an indirect role via regulation of splice factor expression elsewhere on the genome. We targeted Srsf11, which was both alternatively spliced and H3K36me3 enriched in brain following cocaine self-administration. Results: Epigenetic editing of H3K36me3 at Srsf11 was sufficient to drive its alternative splicing and enhanced cocaine self-administration, establishing the direct causal relevance of H3K36me3 to alternative splicing of Srsf11 and to reward behavior.
Project description:Long-lasting changes in neuronal gene expression in brain reward regions, including the nucleus accumbens (NAc), contribute to the persistent functional changes in the addicted brain. Our group and others have demonstrated that altered expression or activity of several candidate transcription factors in NAc regulates drug responses. In a recent study from our group (Feng et al., 2014), involving large-scale genome-wide datasets, E2F3 was predicted as a prominent upstream regulator of cocaine-induced changes in gene expression and alternative splicing. Here, we show that E2F3a, but not E2F3b, expression in NAc regulates cocaine-induced locomotor and reward behavior. Furthermore, we demonstrate that E2F3a overexpression recapitulates a considerable portion of genome-wide transcriptional profiles and alternative splicing induced by cocaine administration. We further validate functional binding of E2F3a at several target genes following cocaine exposure. These novel findings support a crucial role for E2F3a in the regulation of cocaine-elicited behavioral states and molecular mechanisms.
Project description:Global changes in gene expression that underlie the circuit and behavioral dysregulation associated with cocaine addiction remain incompletely understood. Here, we determined how a history of cocaine self-administration (SA) “re-programs” transcriptome-wide responses at baseline and in response to cocaine re-exposure after prolonged withdrawal (WD). We assigned male mice to one of six groups: saline or cocaine SA + 24 hr WD; or saline/cocaine SA + 30 d WD + an acute saline/cocaine challenge within the previous drug-paired context. RNA-seq was then conducted on six interconnected brain reward regions. We focused on patterns of gene expression that were altered by cocaine SA, in particular, molecular targets that show priming or desensitization upon re-exposure to cocaine. Genes that were affected uniquely by acute cocaine after cocaine SA+WD displayed region-specific regulation. The greatest number of regulated genes were seen in nucleus accumbens, dorsal striatum, and basolateral amygdala. Further analysis revealed several transcription factors as key upstream regulators in these three regions, including several not previously implicated in cocaine action. Regulation of subsets of these primed and desensitized genes correlated robustly with SA behavior displayed by individual mice. For example, analysis of transcriptome-wide expression changes revealed that genes associated with cocaine intake respond to contextual information in a region-specific manner. This comprehensive picture of transcriptome-wide regulation by cocaine SA and WD throughout the brain’s reward circuitry provides new insight into the molecular basis of cocaine addiction, which will guide future studies of the key molecular pathways involved.
Project description:Maladaptive reward seeking is a hallmark of cocaine use disorder. To develop therapeutic targets, it is critical to understand the neurobiological changes specific to cocaine-seeking without altering the seeking of natural rewards, e.g., sucrose. The prefrontal cortex (PFC) and the nucleus accumbens core (NAcore) are known regions associated with cocaine- and sucrose-seeking ensembles, i.e., a sparse population of co-activated neurons. Within ensembles, transcriptomic alterations in the PFC and NAcore underlie the learning and persistence of cocaine- and sucrose-seeking behavior. However, transcriptomes exclusively driving cocaine seeking independent from sucrose seeking have not yet been defined using a within-subject approach. Using Ai14:cFos-TRAP2 transgenic mice in a dual cocaine and sucrose self-administration model, we fluorescently sorted (FACS) and characterized (RNAseq) the transcriptomes defining cocaine- and sucrose-seeking ensembles. We found reward- and region-specific transcriptomic changes that will help develop clinically relevant genetic approaches to decrease cocaine-seeking behavior without altering non-drug reward-based positive reinforcement.
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. 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: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.