Reorganization of postmitotic neuronal chromatin accessibility for maturation of serotonergic identity
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PROVIDER: PRJNA770644 | ENA |
REPOSITORIES: ENA
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Project description:Assembly of transcriptomes encoding unique neuronal identities requires selective accessibility of transcription factors to cis-regulatory sequences in nucleosome-embedded postmitotic chromatin. Yet, the mechanisms controlling postmitotic neuronal chromatin accessibility are poorly understood. Here, we show that unique distal enhancers define the Pet1 neuron lineage that generates serotonin (5-HT) neurons. Heterogeneous single cell chromatin landscapes are established early in postmitotic Pet1 neurons and reveal the putative regulatory programs driving Pet1 neuron subtype identities. Distal enhancer accessibility is highly dynamic as Pet1 neurons mature, suggesting the existence of regulatory factors that reorganize postmitotic neuronal chromatin. We find that Pet1 and Lmx1b control chromatin accessibility to select Pet1-lineage specific enhancers for 5-HT neurotransmission. Additionally, these factors are required to maintain chromatin accessibility during early maturation suggesting that postmitotic neuronal open chromatin is unstable and requires continuous regulatory input. Together our findings reveal postmitotic transcription factors that reorganize accessible chromatin for neuron specialization.
2022-04-14 | GSE185737 | GEO
Project description:Areas and layers of the cerebral cortex are specified by genetic programs that are initiated in progenitor cells and then, implemented in postmitotic neurons. Here, we report that Tbr1, a transcription factor expressed in postmitotic projection neurons, exerts positive and negative control over both regional (areal) and laminar identity. Tbr1 null mice exhibited profound defects of frontal cortex and layer 6 differentiation, as indicated by down-regulation of gene-expression markers such as Bcl6 and Cdh9. Conversely, genes that implement caudal cortex and layer 5 identity, such as Bhlhb5 and Fezf2, were up-regulated in Tbr1 mutants. Tbr1 implements frontal identity in part by direct promoter binding and activation of Auts2, a frontal cortex gene implicated in autism. Tbr1 regulates laminar identity in part by downstream activation or maintenance of Sox5, an important transcription factor controlling neuronal migration and corticofugal axon projections. Similar to Sox5 mutants, Tbr1 mutants exhibit ectopic axon projections to the hypothalamus and cerebral peduncle. Together, our findings show that Tbr1 coordinately regulates regional and laminar identity of postmitotic cortical neurons. Mouse E14.5 neocortices and Postnatal day (P) 0.5 brains: E14.5 neocortices KO, 3; E14.5 neocortices WT, 3; Postnatal day (P) 0.5 brains frontal WT, 4; Postnatal day (P) 0.5 brains frontal KO, 4; Postnatal day (P) 0.5 brains parietal WT, 4; Postnatal day (P) 0.5 brains parietal KO, 4; Postnatal day (P) 0.5 brains occipital WT, 4; Postnatal day (P) 0.5 brains occipital KO, 4.
2010-07-27 | E-GEOD-22371 | biostudies-arrayexpress
Project description:Areas and layers of the cerebral cortex are specified by genetic programs that are initiated in progenitor cells and then, implemented in postmitotic neurons. Here, we report that Tbr1, a transcription factor expressed in postmitotic projection neurons, exerts positive and negative control over both regional (areal) and laminar identity. Tbr1 null mice exhibited profound defects of frontal cortex and layer 6 differentiation, as indicated by down-regulation of gene-expression markers such as Bcl6 and Cdh9. Conversely, genes that implement caudal cortex and layer 5 identity, such as Bhlhb5 and Fezf2, were up-regulated in Tbr1 mutants. Tbr1 implements frontal identity in part by direct promoter binding and activation of Auts2, a frontal cortex gene implicated in autism. Tbr1 regulates laminar identity in part by downstream activation or maintenance of Sox5, an important transcription factor controlling neuronal migration and corticofugal axon projections. Similar to Sox5 mutants, Tbr1 mutants exhibit ectopic axon projections to the hypothalamus and cerebral peduncle. Together, our findings show that Tbr1 coordinately regulates regional and laminar identity of postmitotic cortical neurons.
2010-07-27 | GSE22371 | GEO
Project description:Histone variants, which can be expressed outside of S-phase and deposited DNA synthesis-independently, provide long-term histone replacement in postmitotic cells, including neurons. Beyond replenishment, histone variants also play active roles in gene regulation by modulating chromatin states or enabling nucleosome turnover. Here, we uncover crucial roles for the histone H3 variant H3.3 in neuronal development. We find that newborn cortical excitatory neurons, which have only just completed replication-coupled deposition of canonical H3.1 and H3.2, substantially accumulate H3.3 immediately post mitosis. Co-deletion of H3.3-encoding genes H3f3a and H3f3b from newly postmitotic neurons abrogates H3.3 accumulation, markedly alters the histone posttranslational modification (PTM) landscape, and causes widespread disruptions to the establishment of the neuronal transcriptome. These changes coincide with developmental phenotypes in neuronal identities and axon projections. Thus, preexisting, replication-dependent histones are insufficient for establishing neuronal chromatin and transcriptome; de novo H3.3 is required. Stage-dependent deletion of H3f3a and H3f3b from (1) cycling neural progenitor cells, (2) neurons immediately post mitosis, or (3) several days later, reveals the first postmitotic days to be a critical window for de novo H3.3. After H3.3 accumulation within this developmental window, co-deletion of H3f3a and H3f3b does not lead to immediate H3.3 loss, but causes progressive H3.3 depletion over several months without widespread transcriptional disruptions or cellular phenotypes. Our study thus uncovers key developmental roles for de novo H3.3 in establishing neuronal chromatin, transcriptome, identity, and connectivity immediately post mitosis that are distinct from its role in maintaining total histone H3 levels over the neuronal lifespan.
2022-07-27 | GSE181331 | GEO
Project description:Neurons of the CNS must maintain their distinct identity over an entire lifespan. Apart from instructive information provided by transcription factors driving neuron specific genes, other gene programs need to be permanently silenced. The mechanisms governing enduring gene-silencing in neurons are largely unknown, as are the consequences if they fail. Here we show that loss of the Polycomb repressive complex 2 (PRC2) obligate unit Eed in differentiated murine midbrain dopamine (mDA) neurons resulted in progressive loss of the H3K27me3 histone modification followed by upregulation of PRC2 targets, also highly enriched for the constitutive heterochromatin H3K9me3 modification. This was followed by reduced expression of mDA neuron-identity genes, particularly evident in the Substantia nigra pars compacta. Consequently, mDA-neuronal function was severely disrupted, causing parkinsonian-like motor skill deficits. Deletion of Eed in differentiated serotonergic (5HT) neurons resulted in a similar upregulation of PRC2-targets and reduced expression of genes defining 5HT neurons, which promoted loss of serotonergic identity followed by loss of function and altered behaviour. Overall, our results reveal that PRC2 inactivation leads to a selective and progressive loss of mDA or 5HT neuronal identity and function, but not to any loss of cells. Thus, our study shows that PRC2-dependent maintenance of neuronal identity is essential and safeguards against expression of other non-relevant gene programs and loss of neuronal function.
2022-07-11 | GSE189329 | GEO
Project description:Neurons of the CNS must maintain their distinct identity over an entire lifespan. Apart from instructive information provided by transcription factors driving neuron specific genes, other gene programs need to be permanently silenced. The mechanisms governing enduring gene-silencing in neurons are largely unknown, as are the consequences if they fail. Here we show that loss of the Polycomb repressive complex 2 (PRC2) obligate unit Eed in differentiated murine midbrain dopamine (mDA) neurons resulted in progressive loss of the H3K27me3 histone modification followed by upregulation of PRC2 targets, also highly enriched for the constitutive heterochromatin H3K9me3 modification. This was followed by reduced expression of mDA neuron-identity genes, particularly evident in the Substantia nigra pars compacta. Consequently, mDA-neuronal function was severely disrupted, causing parkinsonian-like motor skill deficits. Deletion of Eed in differentiated serotonergic (5HT) neurons resulted in a similar upregulation of PRC2-targets and reduced expression of genes defining 5HT neurons, which promoted loss of serotonergic identity followed by loss of function and altered behaviour. Overall, our results reveal that PRC2 inactivation leads to a selective and progressive loss of mDA or 5HT neuronal identity and function, but not to any loss of cells. Thus, our study shows that PRC2-dependent maintenance of neuronal identity is essential and safeguards against expression of other non-relevant gene programs and loss of neuronal function.
2022-07-11 | GSE189017 | GEO
Project description:Neurons of the CNS must maintain their distinct identity over an entire lifespan. Apart from instructive information provided by transcription factors driving neuron specific genes, other gene programs need to be permanently silenced. The mechanisms governing enduring gene-silencing in neurons are largely unknown, as are the consequences if they fail. Here we show that loss of the Polycomb repressive complex 2 (PRC2) obligate unit Eed in differentiated murine midbrain dopamine (mDA) neurons resulted in progressive loss of the H3K27me3 histone modification followed by upregulation of PRC2 targets, also highly enriched for the constitutive heterochromatin H3K9me3 modification. This was followed by reduced expression of mDA neuron-identity genes, particularly evident in the Substantia nigra pars compacta. Consequently, mDA-neuronal function was severely disrupted, causing parkinsonian-like motor skill deficits. Deletion of Eed in differentiated serotonergic (5HT) neurons resulted in a similar upregulation of PRC2-targets and reduced expression of genes defining 5HT neurons, which promoted loss of serotonergic identity followed by loss of function and altered behaviour. Overall, our results reveal that PRC2 inactivation leads to a selective and progressive loss of mDA or 5HT neuronal identity and function, but not to any loss of cells. Thus, our study shows that PRC2-dependent maintenance of neuronal identity is essential and safeguards against expression of other non-relevant gene programs and loss of neuronal function.
2022-07-11 | GSE189328 | GEO
Project description:The genesis of broad neuronal classes from multipotential neural progenitor cells has been extensively studied, but less is known about the diversification of a single neuronal class into multiple types. We used single-cell RNA-seq to study how newly-born (postmitotic) mouse retinal ganglion cell (RGC) precursors diversify into ~45 discrete types. Computational analysis provides evidence that RGC type identity is not specified at mitotic exit, but acquired by gradual, asynchronous fate restriction of postmitotic multipotential precursors. Some types are not identifiable until a week after they are generated. Immature RGCs may be specified to project ipsilaterally or contralaterally to the rest of the brain before their type identity has been determined. Optimal transport inference identifies groups of RGC precursors with largely non-overlapping fates, distinguished by selectively expressed transcription factors that could act as fate determinants. Our study provides a framework for investigating the molecular diversification of discrete types within a neuronal class.
2022-02-01 | GSE185671 | GEO
Project description:Serotonergic antidepressant drugs have been commonly used to treat mood and anxiety disorders, and increasing evidence suggests potential use of these drugs beyond current antidepressant therapeutics. Facilitation of adult neurogenesis in the hippocampal dentate gyrus has been suggested to be a candidate mechanism of action of antidepressant drugs, but this mechanism may be only one of the broad effects of antidepressants. Here we show a distinct unique action of the serotonergic antidepressant fluoxetine in transforming the phenotype of mature dentate granule cells. Chronic treatments of adult mice with fluoxetine strongly reduced expression of the mature granule cell marker calbindin. The fluoxetine treatment induced active somatic membrane properties resembling immature granule cells and markedly reduced synaptic facilitation that characterizes the mature dentate-to-CA3 signal transmission. These changes cannot be explained simply by an increase in newly generated immature neurons, but best characterized as "dematuration" of mature granule cells. This granule cell dematuration developed along with increases in the efficacy of serotonin in 5-HT(4) receptor-dependent neuromodulation and was attenuated in mice lacking the 5-HT(4) receptor. Our results suggest that serotonergic antidepressants can reverse the established state of neuronal maturation in the adult hippocampus, and up-regulation of 5-HT(4) receptor-mediated signaling may play a critical role in this distinct action of antidepressants. Such reversal of neuronal maturation could affect proper functioning of the mature hippocampal circuit, but may also cause some beneficial effects by reinstating neuronal functions that are lost during development.
| S-EPMC2889553 | biostudies-literature
Project description:The functional and transcriptional maturation of neurons is a prolonged process that extends well beyond mitotic exit and terminal fate commitment of progenitors. The differentiation of cerebellar granule neurons (CGNs) in the postnatal mouse cerebellum provides a useful model to identify chromatin mechanisms that orchestrate temporal changes in transcription as postmitotic CGNs mature. Here we report that CGN maturation is associated with dynamic changes in the genomic distribution of histone H3 lysine 27 trimethylation (H3K27me3), a modification best known for its role in repressing alternative fates during cell specification. H3K27me3 is gained rapidly in newly postmitotic CGNs at progenitor-expressed genes that are repressed in neurons. H3K27me3 is lost more gradually at the promoters of a subset of neuronal genes that are transcriptionally induced upon CGN maturation. The loss of H3K27me3 is facilitated by the lysine demethylase KDM6B, and genes that are induced in maturing CGNs show impaired expression in the cerebellum of conditional KDM6B knockout mice. Genes that lose H3K27me3 gain H3K27 acetylation and binding of the pro-maturation ZIC1/2 transcription factors, suggesting that developmental loss of H3K27me3 may be required to permit the onset of transcriptional maturation. Interestingly, pharmacological inhibition of the H3K27 methyltransferase EZH2 in early postmitotic CGNs not only blocked the repression of progenitor genes but also impaired the induction of mature CGN genes. These data show that regulation of H3K27me3 functions in developing postmitotic neurons beyond the period of cell fate commitment to regulate the dynamics of gene expression programs that underlie functional neuronal maturation.
2022-10-11 | GSE212440 | GEO