RESUMEN
ABSTRACT: Preclinical and clinical work has demonstrated altered plasticity and activity in the nucleus accumbens (NAc) under chronic pain states, highlighting critical therapeutic avenues for the management of chronic pain conditions. In this study, we demonstrate that myocyte enhancer factor 2C (MEF2C), a master regulator of neuronal activity and plasticity, is repressed in NAc neurons after prolonged spared nerve injury (SNI). Viral-mediated overexpression of Mef2c in NAc neurons partially ameliorated sensory hypersensitivity and emotional behaviors in mice with SNI, while also altering transcriptional pathways associated with synaptic signaling. Mef2c overexpression also reversed SNI-induced potentiation of phasic dopamine release and neuronal hyperexcitability in the NAc. Transcriptional changes induced by Mef2c overexpression were different than those observed after desipramine treatment, suggesting a mechanism of action different from antidepressants. Overall, we show that interventions in MEF2C-regulated mechanisms in the NAc are sufficient to disrupt the maintenance of chronic pain states, providing potential new treatment avenues for neuropathic pain.
RESUMEN
Opioid use disorder (OUD) is a neuropsychological disease that has a devastating impact on public health. Substantial individual differences in vulnerability exist, the neurobiological substrates of which remain unclear. To address this question, we investigated genome-wide gene transcription (RNA-seq) and chromatin accessibility (ATAC-seq) in the medial prefrontal cortex (mPFC) of male and female rats exhibiting differential vulnerability in behavioral paradigms modeling different phases of OUD: Withdrawal-Induced Anhedonia (WIA), Demand, and Reinstatement. Ingenuity Pathway Analysis (IPA) of RNA-seq revealed greater changes in canonical pathways in Resilient (vs. Saline) rats in comparison to Vulnerable (vs. Saline) rats across 3 paradigms, suggesting brain adaptations that might contribute to resilience to OUD across its trajectory. Analyses of gene networks and upstream regulators implicated processes involved in oligodendrocyte maturation and myelination in WIA, neuroinflammation in Demand, and metabolism in Reinstatement. Motif analysis of ATAC-seq showed changes in chromatin accessibility to a small set of transcription factor (TF) binding sites as a function either of opioid exposure (i.e., morphine versus saline) generally or of individual vulnerability specifically. Some of these were shared across the 3 paradigms and others were unique to each. In conclusion, we have identified changes in biological pathways, TFs, and their binding motifs that vary with paradigm and OUD vulnerability. These findings point to the involvement of distinct transcriptional and epigenetic mechanisms in response to opioid exposure, vulnerability to OUD, and different stages of the disorder.
RESUMEN
Histone post-translational modifications are critical for mediating persistent alterations in gene expression. By combining unbiased proteomics profiling and genome-wide approaches, we uncovered a role for mono-methylation of lysine 27 at histone H3 (H3K27me1) in the enduring effects of stress. Specifically, mice susceptible to early life stress (ELS) or chronic social defeat stress (CSDS) displayed increased H3K27me1 enrichment in the nucleus accumbens (NAc), a key brain-reward region. Stress-induced H3K27me1 accumulation occurred at genes that control neuronal excitability and was mediated by the VEFS domain of SUZ12, a core subunit of the polycomb repressive complex-2, which controls H3K27 methylation patterns. Viral VEFS expression changed the transcriptional profile of the NAc, led to social, emotional, and cognitive abnormalities, and altered excitability and synaptic transmission of NAc D1-medium spiny neurons. Together, we describe a novel function of H3K27me1 in the brain and demonstrate its role as a "chromatin scar" that mediates lifelong stress susceptibility.
Asunto(s)
Histonas , Lisina , Núcleo Accumbens , Complejo Represivo Polycomb 2 , Estrés Psicológico , Animales , Histonas/metabolismo , Estrés Psicológico/metabolismo , Estrés Psicológico/genética , Ratones , Núcleo Accumbens/metabolismo , Metilación , Lisina/metabolismo , Complejo Represivo Polycomb 2/metabolismo , Complejo Represivo Polycomb 2/genética , Masculino , Ratones Endogámicos C57BL , Neuronas/metabolismo , Procesamiento Proteico-Postraduccional , Derrota SocialRESUMEN
Substance use disorder is characterized by a maladaptive imbalance wherein drug seeking persists despite negative consequences or drug unavailability. This imbalance correlates with neurobiological alterations some of which are amplified during forced abstinence, thereby compromising the capacity of extinction-based approaches to prevent relapse. Cocaine use disorder (CUD) exemplifies this phenomenon in which neurobiological modifications hijack brain reward regions such as the nucleus accumbens (NAc) to manifest craving and withdrawal-like symptoms. While increasing evidence links transcriptional changes in the NAc to specific phases of addiction, genome-wide changes in gene expression during withdrawal vs. extinction (WD/Ext) have not been examined in a context- and NAc-subregion-specific manner. Here, we used cocaine self-administration (SA) in rats combined with RNA-sequencing (RNA-seq) of NAc subregions (core and shell) to transcriptionally profile the impact of experiencing withdrawal in the home cage or in the previous drug context or experiencing extinction training. As expected, home-cage withdrawal maintained drug seeking in the previous drug context, whereas extinction training reduced it. By contrast, withdrawal involving repetitive exposure to the previous drug context increased drug-seeking behavior. Bioinformatic analyses of RNA-seq data revealed gene expression patterns, networks, motifs, and biological functions specific to these behavioral conditions and NAc subregions. Comparing transcriptomic analysis of the NAc of patients with CUD highlighted conserved gene signatures, especially with rats that were repetitively exposed to the previous drug context. Collectively, these behavioral and transcriptional correlates of several withdrawal-extinction settings reveal fundamental and translational information about potential molecular mechanisms to attenuate drug-associated memories.
RESUMEN
Psychosocial stress has profound effects on the body, including the immune system and the brain1,2. Although a large number of pre-clinical and clinical studies have linked peripheral immune system alterations to stress-related disorders such as major depressive disorder (MDD)3, the underlying mechanisms are not well understood. Here we show that expression of a circulating myeloid cell-specific proteinase, matrix metalloproteinase 8 (MMP8), is increased in the serum of humans with MDD as well as in stress-susceptible mice following chronic social defeat stress (CSDS). In mice, we show that this increase leads to alterations in extracellular space and neurophysiological changes in the nucleus accumbens (NAc), as well as altered social behaviour. Using a combination of mass cytometry and single-cell RNA sequencing, we performed high-dimensional phenotyping of immune cells in circulation and in the brain and demonstrate that peripheral monocytes are strongly affected by stress. In stress-susceptible mice, both circulating monocytes and monocytes that traffic to the brain showed increased Mmp8 expression following chronic social defeat stress. We further demonstrate that circulating MMP8 directly infiltrates the NAc parenchyma and controls the ultrastructure of the extracellular space. Depleting MMP8 prevented stress-induced social avoidance behaviour and alterations in NAc neurophysiology and extracellular space. Collectively, these data establish a mechanism by which peripheral immune factors can affect central nervous system function and behaviour in the context of stress. Targeting specific peripheral immune cell-derived matrix metalloproteinases could constitute novel therapeutic targets for stress-related neuropsychiatric disorders.
Asunto(s)
Trastorno Depresivo Mayor , Metaloproteinasa 8 de la Matriz , Monocitos , Estrés Psicológico , Animales , Humanos , Ratones , Trastorno Depresivo Mayor/sangre , Trastorno Depresivo Mayor/enzimología , Trastorno Depresivo Mayor/genética , Trastorno Depresivo Mayor/metabolismo , Espacio Extracelular/metabolismo , Metaloproteinasa 8 de la Matriz/sangre , Metaloproteinasa 8 de la Matriz/deficiencia , Metaloproteinasa 8 de la Matriz/genética , Metaloproteinasa 8 de la Matriz/metabolismo , Ratones Endogámicos C57BL , Monocitos/química , Monocitos/inmunología , Monocitos/metabolismo , Núcleo Accumbens/metabolismo , Núcleo Accumbens/patología , Tejido Parenquimatoso/metabolismo , Análisis de Expresión Génica de una Sola Célula , Conducta Social , Aislamiento Social , Estrés Psicológico/sangre , Estrés Psicológico/genética , Estrés Psicológico/inmunología , Estrés Psicológico/metabolismoRESUMEN
Chronic stress is a major risk factor for Major Depressive Disorder (MDD), and it has been shown to impact the immune system and cause microglia activation in the medial prefrontal cortex (mPFC) involved in the pathogenesis of depression. The aim of this study is to further investigate cellular and molecular mechanisms underlying persistent depression behavior in sex specific manner, which is observed clinically. Here, we report that both male and female mice exhibited depression-like behavior following exposure to chronic stress. However, only female mice showed persistent depression-like behavior, which was associated with microglia activation in mPFC, characterized by distinctive alterations in the phenotype of microglia. Given these findings, to further investigate the underlying molecular mechanisms associated with persistent depression-like behavior and microglia activation in female mice, we used translating-ribosome affinity purification (TRAP). We find that Toll like receptor 4 (TLR4) signaling is casually related to persistent depression-like behavior in female mice. This is supported by the evidence that the fact that genetic ablation of TLR4 expression in microglia significantly reduced the persistent depression-like behavior to baseline levels in female mice. This study tentatively supports the hypothesis that the TLR4 signaling in microglia may be responsible for the sex differences in persistent depression-like behavior in female.
Asunto(s)
Depresión , Trastorno Depresivo Mayor , Receptor Toll-Like 4 , Animales , Femenino , Masculino , Ratones , Trastorno Depresivo Mayor/metabolismo , Microglía/metabolismo , Transducción de Señal , Estrés Psicológico/metabolismo , Receptor Toll-Like 4/metabolismoRESUMEN
Injured neurons sense environmental cues to balance neural protection and axon regeneration, but the mechanisms are unclear. Here, we unveil aryl hydrocarbon receptor (AhR), a ligand-activated bHLH-PAS transcription factor, as molecular sensor and key regulator of acute stress response at the expense of axon regeneration. We demonstrate responsiveness of DRG sensory neurons to ligand-mediated AhR signaling, which functions to inhibit axon regeneration. Ahr deletion mimics the conditioning lesion in priming DRG to initiate axonogenesis gene programs; upon peripheral axotomy, Ahr ablation suppresses inflammation and stress signaling while augmenting pro-growth pathways. Moreover, comparative transcriptomics revealed signaling interactions between AhR and HIF-1α, two structurally related bHLH-PAS α units that share the dimerization partner Arnt/HIF-1ß. Functional assays showed that the growth advantage of AhR-deficient DRG neurons requires HIF-1α; but in the absence of Arnt, DRG neurons can still mount a regenerative response. We further unveil a link between bHLH-PAS transcription factors and DNA hydroxymethylation in response to peripheral axotomy, while neuronal single cell RNA-seq analysis revealed a link of the AhR regulon to RNA polymerase III regulation and integrated stress response (ISR). Altogether, AhR activation favors stress coping and inflammation at the expense of axon regeneration; targeting AhR can enhance nerve repair.
RESUMEN
Substance use disorders (SUDs) induce widespread molecular dysregulation in the nucleus accumbens (NAc), a brain region pivotal for coordinating motivation and reward. These molecular changes are thought to support lasting neural and behavioral disturbances that promote drug-seeking in addiction. However, different drug classes exert unique influences on neural circuits, cell types, physiology, and gene expression despite the overlapping symptomatology of SUDs. To better understand common and divergent molecular mechanisms governing SUD pathology, our goal was to survey cell-type-specific restructuring of the NAc transcriptional landscape in 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 and 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 across drug classes during exposure, whereas D2 MSNs manifest mostly divergent responses between cocaine and morphine, with morphine causing more adaptations in this cell type. Utilizing multiscale embedded gene co-expression network analysis (MEGENA), we discerned transcriptional regulatory networks subserving biological functions shared between cocaine and morphine. We observed largely integrative engagement of overlapping gene networks across drug classes in D1 MSNs, but opposite regulation of key D2 networks, highlighting potential therapeutic gene network targets within MSNs. These studies establish a landmark, cell-type-specific atlas of transcriptional regulation induced by cocaine and by morphine that can serve as a foundation for future studies towards mechanistic understanding of SUDs. Our findings, and future work leveraging this dataset, will pave the way for the development of targeted therapeutic interventions, addressing the urgent need for more effective treatments for cocaine use disorder and enhancing the existing strategies for opioid use disorder.
RESUMEN
Axon regeneration of dorsal root ganglia (DRG) neurons after peripheral axotomy involves reconfiguration of gene regulatory circuits to establish regenerative gene programs. However, the underlying mechanisms remain unclear. Here, through an unbiased survey, we show that the binding motif of Bmal1, a central transcription factor of the circadian clock, is enriched in differentially hydroxymethylated regions (DhMRs) of mouse DRG after peripheral lesion. By applying conditional deletion of Bmal1 in neurons, in vitro and in vivo neurite outgrowth assays, as well as transcriptomic profiling, we demonstrate that Bmal1 inhibits axon regeneration, in part through a functional link with the epigenetic factor Tet3. Mechanistically, we reveal that Bmal1 acts as a gatekeeper of neuroepigenetic responses to axonal injury by limiting Tet3 expression and restricting 5hmC modifications. Bmal1-regulated genes not only concern axon growth, but also stress responses and energy homeostasis. Furthermore, we uncover an epigenetic rhythm of diurnal oscillation of Tet3 and 5hmC levels in DRG neurons, corresponding to time-of-day effect on axon growth potential. Collectively, our studies demonstrate that targeting Bmal1 enhances axon regeneration.
Asunto(s)
Relojes Circadianos , Dioxigenasas , Epigénesis Genética , Regeneración Nerviosa , Células Receptoras Sensoriales , Animales , Ratones , Axones , Relojes Circadianos/genética , Regeneración Nerviosa/genéticaRESUMEN
Infection with the etiological agent of COVID-19, SARS-CoV-2, appears capable of impacting cognition in some patients with post-acute sequelae of SARS-CoV-2 (PASC). To evaluate neuropathophysiological consequences of SARS-CoV-2 infection, we examine transcriptional and cellular signatures in the Brodmann area 9 (BA9) of the frontal cortex and the hippocampal formation (HF) in SARS-CoV-2, Alzheimer's disease (AD), and SARS-CoV-2-infected AD individuals compared to age- and gender-matched neurological cases. Here, we show similar alterations of neuroinflammation and blood-brain barrier integrity in SARS-CoV-2, AD, and SARS-CoV-2-infected AD individuals. Distribution of microglial changes reflected by the increase in Iba-1 reveals nodular morphological alterations in SARS-CoV-2-infected AD individuals. Similarly, HIF-1α is significantly upregulated in the context of SARS-CoV-2 infection in the same brain regions regardless of AD status. The finding may help in informing decision-making regarding therapeutic treatments in patients with neuro-PASC, especially those at increased risk of developing AD.
Asunto(s)
Enfermedad de Alzheimer , COVID-19 , Humanos , SARS-CoV-2 , Barrera Hematoencefálica , Cognición , Progresión de la EnfermedadRESUMEN
Introduction: Infants exposed to opioids in utero are at high risk of exhibiting Neonatal Opioid Withdrawal Syndrome (NOWS), a combination of somatic withdrawal symptoms including high pitched crying, sleeplessness, irritability, gastrointestinal distress, and in the worst cases, seizures. The heterogeneity of in utero opioid exposure, particularly exposure to polypharmacy, makes it difficult to investigate the underlying molecular mechanisms that could inform early diagnosis and treatment of NOWS, and challenging to investigate consequences later in life. Methods: To address these issues, we developed a mouse model of NOWS that includes gestational and post-natal morphine exposure that encompasses the developmental equivalent of all three human trimesters and assessed both behavior and transcriptome alterations. Results: Opioid exposure throughout all three human equivalent trimesters delayed developmental milestones and produced acute withdrawal phenotypes in mice reminiscent of those observed in infants. We also uncovered different patterns of gene expression depending on the duration and timing of opioid exposure (3-trimesters, in utero only, or the last trimester equivalent only). Opioid exposure and subsequent withdrawal affected social behavior and sleep in adulthood in a sex-dependent manner but did not affect adult behaviors related to anxiety, depression, or opioid response. Discussion: Despite marked withdrawal and delays in development, long-term deficits in behaviors typically associated with substance use disorders were modest. Remarkably, transcriptomic analysis revealed an enrichment for genes with altered expression in published datasets for Autism Spectrum Disorders, which correlate well with the deficits in social affiliation seen in our model. The number of differentially expressed genes between the NOWS and saline groups varied markedly based on exposure protocol and sex, but common pathways included synapse development, the GABAergic and myelin systems, and mitochondrial function.
RESUMEN
Here, we construct genome-scale maps for R-loops, three-stranded nucleic acid structures comprised of a DNA/RNA hybrid and a displaced single strand of DNA, in the proliferative and differentiated zones of the human prenatal brain. We show that R-loops are abundant in the progenitor-rich germinal matrix, with preferential formation at promoters slated for upregulated expression at later stages of differentiation, including numerous neurodevelopmental risk genes. RNase H1-mediated contraction of the genomic R-loop space in neural progenitors shifted differentiation toward the neuronal lineage and was associated with transcriptomic alterations and defective functional and structural neuronal connectivity in vivo and in vitro. Therefore, R-loops are important for fine-tuning differentiation-sensitive gene expression programs of neural progenitor cells.
RESUMEN
Tricyclic antidepressants (TCAs), such as desipramine (DMI), are effective at managing neuropathic pain symptoms but often take several weeks to become effective and also lead to considerable side effects. Tianeptine (TIAN) is an atypical antidepressant that activates the mu-opioid receptor but does not produce analgesic tolerance or withdrawal in mice, nor euphoria in humans, at clinically-relevant doses. Here, we evaluate the efficacy of TIAN at persistently alleviating mechanical allodynia in the spared nerve injury (SNI) model of neuropathic pain, even well after drug clearance. After finding an accelerated onset of antiallodynic action compared to DMI, we used genetically modified mice to gain insight into RGS protein-associated pathways that modulate the efficacy of TIAN relative to DMI in models of neuropathic pain. Because we observed similar behavioral responses to both TIAN and DMI treatment in RGS4, RGSz1, and RGS9 knockout mice, we performed RNA sequencing on the NAc of TIAN- and DMI-treated mice after prolonged SNI to further clarify potential mechanisms underlying TIANs faster therapeutic actions. Our bioinformatic analysis revealed distinct transcriptomic signatures between the two drugs, with TIAN more directly reversing SNI-induced differentially expressed genes, and further predicted several upstream regulators that may be implicated in onset of action. This new understanding of the molecular pathways underlying TIAN action may enable the development of novel and more efficacious pharmacological approaches for the management of neuropathic pain.
Asunto(s)
Neuralgia , Humanos , Ratones , Animales , Neuralgia/tratamiento farmacológico , Antidepresivos/uso terapéutico , Hiperalgesia/tratamiento farmacológico , Antidepresivos Tricíclicos/farmacología , Antidepresivos Tricíclicos/uso terapéutico , Modelos Animales de EnfermedadRESUMEN
Opioid use disorder (OUD) looms as one of the most severe medical crises facing society. More effective therapeutics will require a deeper understanding of molecular changes supporting drug-taking and relapse. Here, we develop a brain reward circuit-wide atlas of opioid-induced transcriptional regulation by combining RNA sequencing (RNA-seq) and heroin self-administration in male mice modeling multiple OUD-relevant conditions: acute heroin exposure, chronic heroin intake, context-induced drug-seeking following abstinence, and relapse. Bioinformatics analysis of this rich dataset identified numerous patterns of transcriptional regulation, with both region-specific and pan-circuit biological domains affected by heroin. Integration of RNA-seq data with OUD-relevant behavioral outcomes uncovered region-specific molecular changes and biological processes that predispose to OUD vulnerability. Comparisons with human OUD RNA-seq and genome-wide association study data revealed convergent molecular abnormalities and gene candidates with high therapeutic potential. These studies outline molecular reprogramming underlying OUD and provide a foundational resource for future investigations into mechanisms and treatment strategies.
Asunto(s)
Heroína , Trastornos Relacionados con Opioides , Humanos , Ratones , Masculino , Animales , Heroína/efectos adversos , Estudio de Asociación del Genoma Completo , Encéfalo , Recompensa , RecurrenciaRESUMEN
Histone post-translational modifications are critical for mediating persistent alterations in gene expression. By combining unbiased proteomics profiling, and genome-wide approaches, we uncovered a role for mono-methylation of lysine 27 at histone H3 (H3K27me1) in the enduring effects of stress. Specifically, mice exposed to early life stress (ELS) or to chronic social defeat stress (CSDS) in adulthood displayed increased enrichment of H3K27me1, and transient decreases in H3K27me2, in the nucleus accumbens (NAc), a key brain-reward region. Stress induction of H3K27me1 was mediated by the VEFS domain of SUZ12, a core subunit of the polycomb repressive complex-2, which is induced by chronic stress and controls H3K27 methylation patterns. Overexpression of the VEFS domain led to social, emotional, and cognitive abnormalities, and altered excitability of NAc D1 mediums spiny neurons. Together, we describe a novel function of H3K27me1 in brain and demonstrate its role as a "chromatin scar" that mediates lifelong stress susceptibility.
RESUMEN
Intronic G4C2 hexanucleotide repeat expansions (HRE) of C9orf72 are the most common cause of familial variants of frontotemporal dementia/amyotrophic lateral sclerosis (FTD/ALS). G4C2 HREs in C9orf72 undergo non-canonical repeat-associated translation, producing dipeptide repeat (DPR) proteins, with various deleterious impacts on cellular homeostasis. While five different DPRs are produced, poly(glycine-arginine) (GR) is amongst the most toxic and is the only DPR to accumulate in the associated clinically relevant anatomical locations of the brain. Previous work has demonstrated the profound effects of a poly (GR) model of C9orf72 FTD/ALS, including motor impairment, memory deficits, neurodegeneration, and neuroinflammation. Neuroinflammation is hypothesized to be a driving factor in the disease course; microglia activation is present prior to symptom onset and persists throughout the disease. Here, using an established mouse model of C9orf72 FTD/ALS, we investigate the contributions of the nod-like receptor pyrin-containing 3 (NLRP3) inflammasome in the pathogenesis of FTD/ALS. We find that inflammasome-mediated neuroinflammation is increased with microglial activation, cleavage of caspase-1, production of IL-1ß, and upregulation of Cxcl10 in the brain of C9orf72 FTD/ALS mice. Excitingly, we find that genetic ablation of Nlrp3 significantly improved survival, protected behavioral deficits, and prevented neurodegeneration suggesting a novel mechanism involving HRE-mediated induction of innate immunity. The findings provide experimental evidence of the integral role of HRE in inflammasome-mediated innate immunity in the C9orf72 variant of FTD/ALS pathogenesis and suggest the NLRP3 inflammasome as a therapeutic target.
Asunto(s)
Esclerosis Amiotrófica Lateral , Demencia Frontotemporal , Animales , Ratones , Esclerosis Amiotrófica Lateral/metabolismo , Demencia Frontotemporal/genética , Demencia Frontotemporal/patología , Microglía/metabolismo , Inflamasomas , Proteína C9orf72/genética , Proteína con Dominio Pirina 3 de la Familia NLR/genética , Enfermedades Neuroinflamatorias , Expansión de las Repeticiones de ADN/genética , DipéptidosRESUMEN
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, 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 used CUT&RUN (cleavage under targets and release using nuclease) to map the genome-wide changes in ΔFOSB binding in the 2 main types of nucleus accumbens neurons-D1 or D2 medium spiny neurons-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 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, a finding consistent with earlier studies of ΔFOSB's interacting proteins. Chronic cocaine use induces broad changes in ΔFOSB binding in both D1 and D2 nucleus accumbens medium spiny neurons 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 D2 medium spiny neurons will reveal a broader picture of the function of ΔFOSB and the molecular basis of drug addiction.
Asunto(s)
Trastornos Relacionados con Cocaína , Cocaína , Ratones , Masculino , Femenino , Animales , Cocaína/farmacología , Cocaína/metabolismo , Ratones Transgénicos , Proteínas Proto-Oncogénicas c-fos/genética , Proteínas Proto-Oncogénicas c-fos/metabolismo , Núcleo Accumbens/metabolismo , Ratones Endogámicos C57BLRESUMEN
The complex nature of the transcriptional networks underlying addictive behaviors suggests intricate cooperation between diverse gene regulation mechanisms that go beyond canonical activity-dependent pathways. Here, we implicate in this process a nuclear receptor transcription factor, retinoid X receptor alpha (RXRα), which we initially identified bioinformatically as associated with addiction-like behaviors. In the nucleus accumbens (NAc) of male and female mice, we show that although its own expression remains unaltered after cocaine exposure, RXRα controls plasticity- and addiction-relevant transcriptional programs in both dopamine receptor D1- and D2-expressing medium spiny neurons, which in turn modulate intrinsic excitability and synaptic activity of these NAc cell types. Behaviorally, bidirectional viral and pharmacological manipulation of RXRα regulates drug reward sensitivity in both non-operant and operant paradigms. Together, this study demonstrates a key role for NAc RXRα in promoting drug addiction and paves the way for future studies of rexinoid signaling in psychiatric disease states.
Asunto(s)
Cocaína , Trastornos Mentales , Ratones , Masculino , Femenino , Animales , Núcleo Accumbens/metabolismo , Receptor alfa X Retinoide/genética , Receptor alfa X Retinoide/metabolismo , Neuronas/fisiología , Cocaína/farmacología , Receptores de Dopamina D1/metabolismo , Trastornos Mentales/metabolismo , Recompensa , Ratones Endogámicos C57BLRESUMEN
Psychosocial stress has profound effects on the body, including the peripheral immune system and the brain1,2. Although a large number of pre-clinical and clinical studies have linked peripheral immune system alterations to stress-related disorders such as major depressive disorder (MDD)3,4,5, the underlying mechanisms are not well understood. Here we show that a peripheral myeloid cell-specific proteinase, matrix metalloproteinase 8 (MMP8), is elevated in serum of subjects with MDD as well as in stress-susceptible (SUS) mice following chronic social defeat stress (CSDS). In mice, we show that this increase leads to alterations in extracellular space and neurophysiological changes in the nucleus accumbens (NAc), thereby altering social behaviour. Using a combination of mass cytometry and single-cell RNA-sequencing, we performed high-dimensional phenotyping of immune cells in circulation and brain and demonstrate that peripheral monocytes are strongly affected by stress. Both peripheral and brain-infiltrating monocytes of SUS mice showed increased Mmp8 expression following CSDS. We further demonstrate that peripheral MMP8 directly infiltrates the NAc parenchyma to control the ultrastructure of the extracellular space. Depleting MMP8 prevented stress-induced social avoidance behaviour and alterations in NAc neurophysiology and extracellular space. Collectively, these data establish a novel mechanism by which peripheral immune factors can affect central nervous system function and behaviour in the context of stress. Targeting specific peripheral immune cell-derived matrix metalloproteinases could constitute novel therapeutic targets for stress-related neuropsychiatric disorders.
RESUMEN
Opioid use disorder (OUD) looms as one of the most severe medical crises currently facing society. More effective therapeutics for OUD requires in-depth understanding of molecular changes supporting drug-taking and relapse. Recent efforts have helped advance these aims, but studies have been limited in number and scope. Here, we develop a brain reward circuit-wide atlas of opioid-induced transcriptional regulation by combining RNA sequencing (RNAseq) and heroin self-administration in male mice modeling multiple OUD-relevant conditions: acute heroin exposure, chronic heroin intake, context-induced drug-seeking following prolonged abstinence, and heroin-primed drug-seeking (i.e., "relapse"). Bioinformatics analysis of this rich dataset identified numerous patterns of molecular changes, transcriptional regulation, brain-region-specific involvement in various aspects of OUD, and both region-specific and pan-circuit biological domains affected by heroin. Integrating RNAseq data with behavioral outcomes using factor analysis to generate an "addiction index" uncovered novel roles for particular brain regions in promoting addiction-relevant behavior, and implicated multi-regional changes in affected genes and biological processes. Comparisons with RNAseq and genome-wide association studies from humans with OUD reveal convergent molecular regulation that are implicated in drug-taking and relapse, and point to novel gene candidates with high therapeutic potential for OUD. These results outline broad molecular reprogramming that may directly promote the development and maintenance of OUD, and provide a foundational resource to the field for future research into OUD mechanisms and treatment strategies.