Histone acetylation and other modifications of the chromatin are important regulators of gene expression and, consequently, may contribute to drug-induced behaviors and neuroplasticity. Previous studies have shown that a reduction on histone deacetylase (HDAC) activity results on the enhancement of some psychostimulant-induced behaviors. In the present study, we extend those seminal findings by showing that the administration of the HDAC inhibitor sodium butyrate enhances morphine-induced locomotor sensitization and conditioned place preference. In contrast, this compound has no effects on the development of morphine tolerance and dependence. Similar effects were observed for cocaine and ethanol-induced behaviors. These behavioral changes were accompanied by a selective boosting of a component of the transcriptional program activated by chronic morphine administration that included circadian clock genes and other genes relevant in addictive behavior. Our results support an specific role for histone acetylation and the epigenetic modulation of transcription at a reduced number of biologically relevant loci on non-homeostatic, long lasting, drug-induced behavioral plasticity. To further investigate the molecular bases of sodium butyrate action on long-lasting behavioral responses to morphine, we screened for potential substrates of their interaction by performing a genome-wide comparison of the striatal transcriptome after chronic administration of morphine in the absence or presence of sodium butyrate.
Selective boosting of transcriptional and behavioral responses to drugs of abuse by histone deacetylase inhibition.
Sex, Age, Specimen part
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Genomic landscape of transcriptional and epigenetic dysregulation in early onset polyglutamine disease.
Sex, Age, Specimen part
View SamplesTranscriptional dysregulation is an important early feature of polyglutamine diseases. One of its proposed causes is defective neuronal histone acetylation, but important aspects of this hypothesis, such as the precise genomic topography of acetylation deficits
Genomic landscape of transcriptional and epigenetic dysregulation in early onset polyglutamine disease.
Sex, Age, Specimen part
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Genomic targets, and histone acetylation and gene expression profiling of neural HDAC inhibition.
Sex, Age, Specimen part, Treatment
View SamplesHistone deacetylase inhibitors (HDACis) have been shown to potentiate hippocampal-dependent memory and synaptic plasticity and to ameliorate cognitive deficits and degeneration in animal models for different neuropsychiatric conditions. However, the impact of these drugs on hippocampal histone acetylation and gene expression profiles at the genomic level, and the molecular mechanisms that underlie their specificity and beneficial effects in neural tissue, remains obscure. Here, we mapped four relevant histone marks (H3K4me3, AcH3K9,14, AcH4K12 and pan-AcH2B) in hippocampal chromatin and investigated at the whole-genome level the impact of HDAC inhibition on acetylation profiles and basal and activity-driven gene expression. HDAC inhibition caused a dramatic histone hyperacetylation that was largely restricted to active loci pre-marked with H3K4me3 and AcH3K9,14. In addition, the comparison of Chromatin immunoprecipitation sequencing and gene expression profiles indicated that Trichostatin A-induced histone hyperacetylation, like histone hypoacetylation induced by histone acetyltransferase deficiency, had a modest impact on hippocampal gene expression and did not affect the transient transcriptional response to novelty exposure. However, HDAC inhibition caused the rapid induction of a homeostatic gene program related to chromatin deacetylation. These results illuminate both the relationship between hippocampal gene expression and histone acetylation and the mechanism of action of these important neuropsychiatric drugs.
Genomic targets, and histone acetylation and gene expression profiling of neural HDAC inhibition.
Specimen part
View SamplesMethods: CaMKIIa-creERT2 (Erdmann et al., 2007) and Dicer1f/f (Harfe et al., 2005) were crossed to produce inducible forebrain-restricted Dicer1 knockout mice (Dicer-ifKO) mice. Hippocampal mRNA profiles of 3-month-old wild-type (WT) and (Dicer-ifKO) mice were generated by deep sequencing, in triplicate, using Illumina HiSeq 2500. Each sample included total RNA isolated from the hippocampus of 3 mice. In total, 12 mice per genotype were used. The sequence reads that passed quality filters were mapped to reference genome (GRCm38/mm10) using Bowtie 2 (2.0.5) and TopHat (2.0.6). SAM/BAM files were further processed with Samtools (0.1.18). Read count quantitations were obtained using Seqmonk (0.26.0). Normalization of read counts and differential expression analysis between genotypes was carried out using DESeq2 R package from Bioconductor (Release 2.13). qRT–PCR validation was performed using SYBR Green assays. Results: We mapped about 13-14 million sequence reads per sample to the mouse genome (build GRCm38/mm10) and quantified 76,938 annotated transcripts. DESeq2 R package was used to normalize the counts and perform the differential expression. Differential analysis output was filtered by FDR threshold (padj < 0.1). This approach led us to identify 641 gene isoforms, corresponding to 314 genes that were differentially regulated in the mouse hippocampus upon Dicer ablation. Conclusions: We extend here the characterization of inducible forebrain-restricted Dicer1 mutants confirming the initial memory improvement. Moreover, we describe several novel phenotypes associated with early Dicer loss in the mature brain including an exacerbated response to seizures, increased CA1 neuron excitability, a pronounced weight gain and enhanced induction of immediate early genes (IEGs) in relevant neuronal nuclei. To identify candidate genes that could explain these phenotypes, we conducted two complementary genomic screens for the miRNAs primarily affected and their targets. Overall, our results explain both the initial and late consequences of Dicer loss in excitatory neurons and indicate that Dicer and the miRNA system play a critical role regulating neuronal homeostasis and responsiveness. Overall design: Hippocampal mRNA profiles of 3-month-old wild-type (WT) and Dicer-ifKO (3 weeks upon tamoxifen administration) male mice were generated by deep sequencing, in triplicate, using Illumina HiSeq 2500. Each sample included total RNA isolated from the hippocampus of 3 mice. In total, 12 mice per genotype were used.
Blocking miRNA Biogenesis in Adult Forebrain Neurons Enhances Seizure Susceptibility, Fear Memory, and Food Intake by Increasing Neuronal Responsiveness.
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View SamplesThe epigenetic changes of the chromatin represent an attractive molecular substrate for adaptation to the environment. We examined here the role of CBP, a histone acetyltransferase involved in mental retardation, in the genesis and maintenance of long-lasting systemic and behavioral adaptations to environmental enrichment (EE). Morphological and behavioral analyses demonstrated that EE ameliorates deficits associated to CBP-deficiency. However, CBP-deficient mice also showed a strong defect in environment-induced neurogenesis and impaired EE-enhanced spatial navigation and patter separation ability. These defects correlated with an attenuation of the transcriptional program induced in response to EE and with deficits in histone acetylation at the promoters of EE-regulated, neurogenesis-related genes. Additional experiments in CBP restricted and inducible knockout mice indicated that environment-induced adult neurogenesis is extrinsically regulated by CBP function in mature granule cells. Overall, our experiments demonstrate that the environment alters gene expression by impinging on activities involved in modifying the epigenome and identify CBP-dependent transcriptional neuroadaptation as an important mediator of EE-induced benefits, a finding with important implications for mental retardation therapeutics.
CBP is required for environmental enrichment-induced neurogenesis and cognitive enhancement.
Sex, Age, Specimen part
View SamplesQuantitative Analysis of cortical transcriptomes through Next Generation Sequencing (RNA-Seq) from wild-type mice, wild-type mice treated with IL1b (200 ng/mouse, 14h), IL-1R8-/- mice and IL-1R8-/- mice treated with IL1b antagonist Anakinra (25 mg/kg per day for 3 consecutive days, i.p. administration). mRNA profiles of cortical tissue from adult wild-type mice, wild-type mice treated with IL1b (200 ng/kg, 14h), IL-1R8-/- mice (Garlanda et al., 2004), and IL-1R8-/- mice treated with Anakinra (25 mg/kg per day for 3 consecutive days, i.p. administration) were generated by next-generation sequencing (RNA-seq) using Illumina HiSeq 2500 apparatus in paired-end configuration (2x125bp). Each condition was assessed in triplicate (12 mRNA-seq libraries) and, to reduce biological variability, each mRNA library was generated from pooled total RNA isolated from cortical tissue of 3 individual mice. In total, 9 mice per condition were used. Libraries were stranded and multiplexed. To increase sequencing depth, libraries were sequenced in two different lanes. All the libraries were loaded in each of the two lanes. Quality control of the raw data was performed with FastQC (http://www.bioinformatics.babraham.ac.uk/projects/fastqc/). Libraries were trimmed for adapter removal using Trimmomatic (Bolger et al., 2014) and mapped to reference genome (Ensembl GRCm38) using TopHat2 (Kim et al., 2013) and Bowtie2 (Langmead et al., 2009). Library sizes of primary mapped reads were between 70 and 96 million reads. Samtools was used to manipulate BAM files (Li et al., 2009). For calling of differentially expressed genes (DEG), mapped reads were counted with HTSeq v0.6.1 (Anders et al., 2014) and count tables were analysed using DeSeq2 v1.10.1 R-package (Love et al., 2014) with a design of one factor with four levels (“wild-type”, “wild-type + IL1?”, “IL-1R8-/-”, “IL-1R8-/- + Anakinra"), and differences between groups were tested using contrasts for wild-type + IL1b versus wild-type; IL-1R8-/- versus wild-type; IL-1R8-/- + Kineret versus wild-type. For consideration of differentially regulated genes between conditions, we used adjusted p-value < 0.1 or adjusted p-value < 0.05 as indicated in the manuscript. Overall design: mRNA profiles in adult mouse cerebral cortex of wild type (WT), WT mice treated with IL1b (200 ng/kg, 14h), IL-1R8-/- mice, and IL-1R8-/- mice treated with IL1b antagonist Anakinra (25 mg/kg per day for 3 consecutive days, i.p. administration) were generated by deep sequencing, in triplicate, using Illumina HiSeq 2500. Each sample was prepared by pooling cortical tissue from 3 idenpendent mice.
Lack of IL-1R8 in neurons causes hyperactivation of IL-1 receptor pathway and induces MECP2-dependent synaptic defects.
Treatment, Subject
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Loss of neuronal 3D chromatin organization causes transcriptional and behavioural deficits related to serotonergic dysfunction.
Sex, Specimen part
View SamplesThe interior of the eukaryotic cell nucleus is a highly organized 3D structure. In mature hippocampal and cortical pyramidal neurons, transcriptionally silent DNA is typically compacted in a few clusters referred to as chromocenters that are strongly stained with DNA intercalating agents like DAPI and whose function is still uncertain. We found that this 3D structure was severely disrupted by the incorporation of the chimeric histone H2BGFP into neuronal chromatin. Experiments in inducible and forebrain restricted bitransgenic mice demonstrated that the expression of this histone alters the higher-order organization of neuronal heterochromatin and causes a complex behavioral phenotype that includes hyperactivity, and social interaction, prepulse inhibition and cognitive defects. This phenotype was associated with highly specific transcriptional deficits that affected several serotonin receptor genes located at the edge of gene desert regions. Pharmacological and electrophysiological experiments indicate that this epigenetically-induced hyposerotonergic state may underlie the behavioral defects. Our results suggest a new role for perinuclear heterochromatin and chromocenter organization in the epigenetic regulation of neuronal gene expression and mental illness.
Loss of neuronal 3D chromatin organization causes transcriptional and behavioural deficits related to serotonergic dysfunction.
Specimen part
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