Shared and divergent transcriptomic regulation in nucleus accumbens D1 and D2 medium spiny neurons by cocaine
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ABSTRACT: Substance use disorders (SUDs) induce widespread molecular dysregulation in nucleus accumbens (NAc), a brain region pivotal for coordinating motivation and reward, which is linked to neural and behavioral disturbances promoting addiction. Despite the overlapping symptomatology of SUDs, different drug classes exert partly unique influences on neural circuits, cell types, physiology, and gene expression. To better understand common and divergent molecular mechanisms governing SUD pathology, we characterized the cell-type-specific restructuring of the NAc transcriptional landscape after psychostimulant or opioid exposure. We combined fluorescence-activated nuclei sorting and RNA sequencing to profile NAc D1 and D2 medium spiny neurons (MSNs) across cocaine exposure paradigms, including initial exposure, prolonged withdrawal after repeated exposure, and re-exposure post-withdrawal. Our analyses reveal that D1 MSNs display many convergent transcriptional responses across the two drugs, whereas D2 MSNs manifest highly divergent responses, with morphine causing far more adaptations in this cell type.
Project description:Substance use disorders (SUDs) induce widespread molecular dysregulation in nucleus accumbens (NAc), a brain region pivotal for coordinating motivation and reward, which is linked to neural and behavioral disturbances promoting addiction. Despite the overlapping symptomatology of SUDs, different drug classes exert partly unique influences on neural circuits, cell types, physiology, and gene expression. To better understand common and divergent molecular mechanisms governing SUD pathology, we characterized the cell-type-specific restructuring of the NAc transcriptional landscape after psychostimulant or opioid exposure. We combined fluorescence-activated nuclei sorting and RNA sequencing to profile NAc D1 and D2 medium spiny neurons (MSNs) across morphine exposure paradigms, including initial exposure, prolonged withdrawal after repeated exposure, and re-exposure post-withdrawal. Our analyses reveal that D1 MSNs display many convergent transcriptional responses, whereas D2 MSNs manifest highly divergent responses, with morphine causing far more adaptations in this cell type.
Project description:Use of addictive substances often creates powerful and enduring associations with external cues that act as relapse triggers in individuals recovering from a substance use disorder (SUD). In the reward-associated brain region, the nucleus accumbens (NAc), drug use or drug-associated cue exposure activates a subset of D1 dopamine receptor-expressing medium spiny neurons (D1-MSNs), which typically promotes drug seeking, and a smaller subset of D2 dopamine receptor-expressing MSNs (D2-MSNs), which typically opposes drug seeking. The activity-regulated transcription factor, Neuronal PAS Domain Protein 4 (NPAS4), is activated in a small subset of NAc neurons during cocaine conditioning, and NAc NPAS4 is required for drug-context memories. Using a new Npas4-TRAP mouse combined with chemogenetics, we found that the during cocaine conditioning, the NPAS4-positive ensemble is required for drug-context associations. Single-cell transcriptomic analyses and in situ hybridization of NAc tissues from drug-conditioned mice revealed that NPAS4 is expressed predominantly in MSNs, and using cell type-specific molecular genetic approaches, we found that NPAS4 in D2-MSNs, but not D1-MSNs, was required for both drug-context associations and cue-reinstated cocaine seeking. Similarly, NPAS4 in NAc D2-MSNs, but not D1-MSNs, blocked cocaine experience-dependent strengthening of glutamatergic prefrontal cortical (PFC) inputs onto D2-MSNs. Analysis of differential gene expression in D2-MSNs revealed that NPAS4 and cocaine conditioning influence a gene expression program associated with synapses, dendrites, neuronal projections, dopamine, and cocaine. Together, our data reveal that NPAS4 functions during active cocaine use to maintain the imbalance of D1-MSN:D2-MSN activation and cue-induced drug seeking by suppressing excitatory drive onto relapse-opposing NAc D2-MSN circuits.
Project description:A hallmark of addiction is the ability of drugs of abuse to trigger relapse after periods of prolonged abstinence. Here, we describe a novel epigenetic mechanism whereby chronic cocaine exposure causes lasting chromatin and downstream transcriptional modifications in the nucleus accumbens (NAc), a critical brain region controlling motivation. We link prolonged withdrawal from cocaine to the depletion of the histone variant H2A.Z, coupled with increased genome accessibility and latent priming of gene transcription, in D1 dopamine receptor-expressing medium spiny neurons (D1 MSNs) that relate to aberrant gene expression upon drug relapse. The histone chaperone ANP32E removes H2A.Z from chromatin, and we demonstrate that D1 MSN-selective Anp32e knockdown prevents cocaine-induced H2A.Z depletion and blocks cocaine’s rewarding actions. By contrast, very different effects of cocaine exposure, withdrawal, and relapse were found for D2 MSNs. These findings establish histone variant exchange as an important mechanism and clinical target engaged by drugs of abuse to corrupt brain function and behavior.
Project description:A hallmark of addiction is the ability of drugs of abuse to trigger relapse after periods of prolonged abstinence. Here, we describe a novel epigenetic mechanism whereby chronic cocaine exposure causes lasting chromatin and downstream transcriptional modifications in the nucleus accumbens (NAc), a critical brain region controlling motivation. We link prolonged withdrawal from cocaine to the depletion of the histone variant H2A.Z, coupled with increased genome accessibility and latent priming of gene transcription, in D1 dopamine receptor-expressing medium spiny neurons (D1 MSNs) that relate to aberrant gene expression upon drug relapse. The histone chaperone ANP32E removes H2A.Z from chromatin, and we demonstrate that D1 MSN-selective Anp32e knockdown prevents cocaine-induced H2A.Z depletion and blocks cocaine’s rewarding actions. By contrast, very different effects of cocaine exposure, withdrawal, and relapse were found for D2 MSNs. These findings establish histone variant exchange as an important mechanism and clinical target engaged by drugs of abuse to corrupt brain function and behavior.
Project description:The striatum is the main input structure of the basal ganglia, receiving information from the cortex and the thalamus and consisting of D1- and D2- medium spiny neurons (MSNs). D1-MSNs and D2-MSNs are essential for motor control and cognitive behaviors and have implications in Parkinson’s Disease. In the present study, we demonstrated that Sp9 positive progenitors produced both D1-MSNs and D2-MSNs and that Sp9 expression was rapidly downregulated in postmitotic D1-MSNs. Furthermore, we found that sustained Sp9 expression in lateral ganglionic eminence (LGE) progenitor cells and their descendants led to promoting D2-MSNs identity and repressing D1-MSNs identity during striatal development. As a result, sustained Sp9 expression resulted in an imbalance between D1-MSNs and D2-MSNs in the mouse striatum. In addition, the fate-changed D2 like-MSNs survived normally in adulthood. Taken together, our finding supported that Sp9 was sufficient to promote D2-MSNs identity and repress D1-MSNs identity, and Sp9 was a negative regulator of D1-MSNs fate. The striatum is the main input structure of the basal ganglia, receiving information from the cortex and the thalamus and consisting of D1- and D2- medium spiny neurons (MSNs). D1-MSNs and D2-MSNs are essential for motor control and cognitive behaviors and have implications in Parkinson’s Disease. In the present study, we demonstrated that Sp9 positive progenitors produced both D1-MSNs and D2-MSNs and that Sp9 expression was rapidly downregulated in postmitotic D1-MSNs. Furthermore, we found that sustained Sp9 expression in lateral ganglionic eminence (LGE) progenitor cells and their descendants led to promoting D2-MSNs identity and repressing D1-MSNs identity during striatal development. As a result, sustained Sp9 expression resulted in an imbalance between D1-MSNs and D2-MSNs in the mouse striatum. In addition, the fate-changed D2 like-MSNs survived normally in adulthood. Taken together, our finding supported that Sp9 was sufficient to promote D2-MSNs identity and repress D1-MSNs identity, and Sp9 was a negative regulator of D1-MSNs fate.
Project description:The striatum is the main input structure of the basal ganglia, receiving information from the cortex and the thalamus and consisting of D1- and D2- medium spiny neurons (MSNs). D1-MSNs and D2-MSNs are essential for motor control and cognitive behaviors and have implications in Parkinson’s Disease. In the present study, we demonstrated that Sp9 positive progenitors produced both D1-MSNs and D2-MSNs and that Sp9 expression was rapidly downregulated in postmitotic D1-MSNs. Furthermore, we found that sustained Sp9 expression in lateral ganglionic eminence (LGE) progenitor cells and their descendants led to promoting D2-MSNs identity and repressing D1-MSNs identity during striatal development. As a result, sustained Sp9 expression resulted in an imbalance between D1-MSNs and D2-MSNs in the mouse striatum. In addition, the fate-changed D2 like-MSNs survived normally in adulthood. Taken together, our finding supported that Sp9 was sufficient to promote D2-MSNs identity and repress D1-MSNs identity, and Sp9 was a negative regulator of D1-MSNs fate.
Project description:Background The ability of neurons to respond to external stimuli involves adaptations of gene expression. Induction of the transcription factor, ΔFOSB, in the nucleus accumbens (NAc), a key brain reward region, is important for the development of drug addiction. However, a comprehensive map of ΔFOSB’s gene targets has not yet been generated. Methods We use CUT&RUN to map the genome-wide changes in ΔFOSB binding in the two main types of NAc neurons—D1 or D2 medium spiny neurons (MSNs)—after chronic cocaine exposure. To annotate genomic regions of ΔFOSB binding sites, we also examined the distributions of several histone modifications. Resulting datasets were leveraged for multiple bioinformatic analyses. Results The majority of ΔFOSB peaks occur outside of promoter regions, including intergenic regions, and are surrounded by epigenetic marks indicative of active enhancers. BRG1, the core subunit of the SWI/SNF chromatin remodeling complex, overlaps with ΔFOSB peaks, consistent with earlier studies of ΔFOSB’s interacting proteins. Chronic cocaine induces broad changes in ΔFOSB binding in both D1 and D2 NAc MSNs of male and female mice. In addition, in silico analyses predict that ΔFOSB cooperatively regulates gene expression with homeobox and T-box transcription factors. Conclusions These novel findings uncover key elements of ΔFOSB’s molecular mechanisms in transcriptional regulation at baseline and in response to chronic cocaine exposure. Further characterization of ΔFOSB’s collaborative transcriptional and chromatin partners specifically in D1 and in D2 MSNs will reveal a broader picture of the function of ΔFOSB and the molecular basis of drug addiction.
Project description:Background: Depression is the leading cause of disability which produces enormous health and economic burdens. In the reward circuitry, the nucleus accumbens (NAc) is a key brain region of depression pathophysiology, possibly based on differential activities of D1- or D2-type medium spiny neurons (MSNs). Methods: To separate D1- or D2-MSN specific transcriptomes in the NAc, RiboTag (RT) mice were crossed with D1- or D2-Cre lines and subjected to chronic social defeat stress. The cell-type specifically tagged ribosome-mRNA complex was pulled down by anti-HA antibody, and purified RNAs were subjected to RNA sequencing. Sequencing data were analyzed and defined differentially expressed genes (DEGs) were validated with RNAscope and viral overexpression in vivo. Results: Both MSN subtypes express distinct gene expression profiles according to stress groups. The DEGs are correlated with depression relevant gene ontology terms. Behavioral susceptibility and resilience are also correlated with subsets of DEGs, especially in D1-MSNs. Conclusions: Distinct subsets of genes are modulated in a cell-type specific manner in the NAc of depressed mice. Here we provided valuable transcriptome data sets for future studies on depression.
Project description:∆FosB, a transcription factor that accumulates in nucleus accumbens (NAc) after exposure to virtually every known rewarding substance, has been shown to directly control gene transcription and behavior downstream of both cocaine and opioid exposure but with potentially different roles in D1 and D2 medium spiny neurons (MSNs). To clarify MSN subtype-specific roles for ∆FosB, and investigate how these subtypes coordinate the actions of distinct classes of addictive drugs, we developed a CRISPR/Cas9-based epigenome editing tool to induce endogenous ∆FosB expression in vivo in the absence of drug exposure and performed RNA-sequencing on bulk male and female NAc tissue.
Project description:Opioid abuse produces enduring associations between the drug euphoria and features of the drug-taking experience, and these powerful associations can trigger relapse in individuals recovering from opioid use disorder. We show here that the epigenetic enzyme, histone deacetylase 5 (HDAC5), functions in the nucleus accumbens (NAc) during active heroin use to limit future relapse-like behavior. Moreover, enhancing HDAC5 function in NAc dramatically suppresses context-associated and reinstated heroin seeking behaviors, but it does not impact sucrose seeking. We also find that HDAC5 functions within dopamine D1 receptor-expressing medium spiny neurons (MSNs) to suppress cue-induced heroin seeking, but within dopamine D2 receptor-expressing MSNs to suppress drug-primed heroin seeking. Using cell type-specific transcriptomics analysis, we found that HDAC5 reduces expression of numerous genes linked to ion transport, and it decreases intrinsic excitability of NAc MSNs, suggesting that HDAC5 limits relapse vulnerability by suppressing NAc MSN firing rates during active heroin use. We used microarrays to define genes differentially expressed in the presence or absence of AAV2-DIO-HDAC5-3SA in both D1 and D2 cell-types derived from Nucleus accumbens following vTRAP.