Genome-wide activity-dependent MeCP2 phosphorylation regulates nervous system development and function [visual cortex]
Ontology highlight
ABSTRACT: Autism spectrum disorders such as Rett syndrome (RTT) have been hypothesized to arise from defects in experience-dependent synapse maturation. RTT is caused by mutations in MECP2, a nuclear protein that becomes phosphorylated at S421 in response to neuronal activation. We show here that disruption of MeCP2 S421 phosphorylation in vivo results in defects in synapse development and behavior, implicating activity-dependent regulation of MeCP2 in brain development and RTT. We investigated the mechanism by which S421 phosphorylation regulates MeCP2 function and show by chromatin immunoprecipitation-sequencing that this modification occurs on MeCP2 bound across the genome. The phosphorylation of MeCP2 S421 appears not to regulate the expression of specific genes; rather, MeCP2 functions as a histone-like factor whose phosphorylation may facilitate a genome-wide response of chromatin to neuronal activity during nervous system development. We propose that RTT results in part from a loss of this experience-dependent chromatin remodeling. Gene expression analysis of RNA isolated from P17 mouse visual cortex was performed comparing global gene expression between Wild-Type and MeCP2 S421A knock-in mice.
Project description:Autism spectrum disorders such as Rett syndrome (RTT) have been hypothesized to arise from defects in experience-dependent synapse maturation. RTT is caused by mutations in MECP2, a nuclear protein that becomes phosphorylated at S421 in response to neuronal activation. We show here that disruption of MeCP2 S421 phosphorylation in vivo results in defects in synapse development and behavior, implicating activity-dependent regulation of MeCP2 in brain development and RTT. We investigated the mechanism by which S421 phosphorylation regulates MeCP2 function and show by chromatin immunoprecipitation-sequencing that this modification occurs on MeCP2 bound across the genome. The phosphorylation of MeCP2 S421 appears not to regulate the expression of specific genes; rather, MeCP2 functions as a histone-like factor whose phosphorylation may facilitate a genome-wide response of chromatin to neuronal activity during nervous system development. We propose that RTT results in part from a loss of this experience-dependent chromatin remodeling. Gene expression analysis of RNA isolated from P17 mouse visual cortex was performed comparing global gene expression between Wild-Type and MeCP2 S421A knock-in mice. We isolated RNA from the visual cortex of 4 wild-type and 4 MeCP2 S421A littermate P17 Mice, and analyzed mRNA expression using the Affymetrix Mouse Gene 1.0 ST microarray platform.
Project description:Autism spectrum disorders such as Rett syndrome (RTT) have been hypothesized to arise from defects in experience-dependent synapse maturation. RTT is caused by mutations in MECP2, a nuclear protein that becomes phosphorylated at S421 in response to neuronal activation. We show here that disruption of MeCP2 S421 phosphorylation in vivo results in defects in synapse development and behavior, implicating activity-dependent regulation of MeCP2 in brain development and RTT. We investigated the mechanism by which S421 phosphorylation regulates MeCP2 function and show by chromatin immunoprecipitation-sequencing that this modification occurs on MeCP2 bound across the genome. The phosphorylation of MeCP2 S421 appears not to regulate the expression of specific genes; rather, MeCP2 functions as a histone-like factor whose phosphorylation may facilitateM-CM-^BM-BM- a genome-wide response of chromatin to neuronal activity during nervous system development. We propose that RTT results in part from a loss of this experience-dependent chromatin remodeling. To examine MeCP2 binding across the neuronal genome and where on the genome MeCP2 is phosphorylated at Serine 421 in response to neuronal activity we performed anti-total MeCP2 and anti-phospho-Serine 421 specific Chromatin immunoprecipitation from cultured cortical neurons that were either left unstimulated or membrane depolarized for 2 hours by addition of 55mM KCl to the media. ChIP DNA was verified for successful IP by qPCR then cloned and sequenced using ABI SOLiD system 4. ChIP was performed from E16 +7DIV disociated cortical cultures from one or two independent dissections using an anti-c-terminal antiserum recognizing MeCP2 independent of its phosphorylation state or with an anti-pS421 antiserum that specifically immunoprecipitates MeCP2 phosphorylated at serine 421. Samples were qPCR validated and sequenced using ABI SOLiD system 4 library preparation and sequencing.
Project description:Autism spectrum disorders such as Rett syndrome (RTT) have been hypothesized to arise from defects in experience-dependent synapse maturation. RTT is caused by mutations in MECP2, a nuclear protein that becomes phosphorylated at S421 in response to neuronal activation. We show here that disruption of MeCP2 S421 phosphorylation in vivo results in defects in synapse development and behavior, implicating activity-dependent regulation of MeCP2 in brain development and RTT. We investigated the mechanism by which S421 phosphorylation regulates MeCP2 function and show by chromatin immunoprecipitation-sequencing that this modification occurs on MeCP2 bound across the genome. The phosphorylation of MeCP2 S421 appears not to regulate the expression of specific genes; rather, MeCP2 functions as a histone-like factor whose phosphorylation may facilitate a genome-wide response of chromatin to neuronal activity during nervous system development. We propose that RTT results in part from a loss of this experience-dependent chromatin remodeling. To examine MeCP2 binding across the neuronal genome and where on the genome MeCP2 is phosphorylated at Serine 421 in response to neuronal activity we performed anti-total MeCP2 and anti-phospho-Serine 421 specific Chromatin immunoprecipitation from cultured cortical neurons that were either left unstimulated or membrane depolarized for 2 hours by addition of 55mM KCl to the media. ChIP DNA was verified for successful IP by qPCR then cloned and sequenced using ABI SOLiD system 4.
Project description:Mutations in MECP2 give rise to Rett syndrome (RTT), an X-linked neurodevelop- mental disorder that results in broad cognitive impairments in females. While the exact etiology of RTT symptoms remains unknown, one possible explanation for its clinical presentation is that loss of MeCP2 causes miswiring of neural circuits due to defects in the brain’s capacity to respond to changes in neuronal activity and sensory experience. Here, we show that MeCP2 is phosphorylated at four residues in the brain (S86, S274, T308, and S421) in response to neuronal activity, and we generate a quadruple knock-in (QKI) mouse line in which all four activity-dependent sites are mutated to alanines to prevent phosphorylation. QKI mice do not display overt RTT phenotypes or detectable gene expression changes in two brain regions. However, electrophysiological recordings from the retinogeniculate synapse of QKI mice reveal that while synapse elimination is initially normal at P14, it is significantly compromised at P20. Notably, this phenotype is distinct from the synapse refinement defect previously reported for Mecp2 null mice, where synapses initially refine but then regress after the third postnatal week. We thus propose a model in which activity-induced phosphorylation of MeCP2 is critical for the proper timing of retinogeniculate synapse maturation specifically during the early postnatal period.
Project description:Mutations in MECP2 give rise to Rett syndrome (RTT), an X-linked neurodevelop- mental disorder that results in broad cognitive impairments in females. While the exact etiology of RTT symptoms remains unknown, one possible explanation for its clinical presentation is that loss of MeCP2 causes miswiring of neural circuits due to defects in the brain’s capacity to respond to changes in neuronal activity and sensory experience. Here, we show that MeCP2 is phosphorylated at four residues in the brain (S86, S274, T308, and S421) in response to neuronal activity, and we generate a quadruple knock-in (QKI) mouse line in which all four activity-dependent sites are mutated to alanines to prevent phosphorylation. QKI mice do not display overt RTT phenotypes or detectable gene expression changes in two brain regions. However, electrophysiological recordings from the retinogeniculate synapse of QKI mice reveal that while synapse elimination is initially normal at P14, it is significantly compromised at P20. Notably, this phenotype is distinct from the synapse refinement defect previously reported for Mecp2 null mice, where synapses initially refine but then regress after the third postnatal week. We thus propose a model in which activity-induced phosphorylation of MeCP2 is critical for the proper timing of retinogeniculate synapse maturation specifically during the early postnatal period.
Project description:Mutations in MECP2 give rise to Rett syndrome (RTT), an X-linked neurodevelop- mental disorder that results in broad cognitive impairments in females. While the exact etiology of RTT symptoms remains unknown, one possible explanation for its clinical presentation is that loss of MeCP2 causes miswiring of neural circuits due to defects in the brain’s capacity to respond to changes in neuronal activity and sensory experience. Here, we show that MeCP2 is phosphorylated at four residues in the brain (S86, S274, T308, and S421) in response to neuronal activity, and we generate a quadruple knock-in (QKI) mouse line in which all four activity-dependent sites are mutated to alanines to prevent phosphorylation. QKI mice do not display overt RTT phenotypes or detectable gene expression changes in two brain regions. However, electrophysiological recordings from the retinogeniculate synapse of QKI mice reveal that while synapse elimination is initially normal at P14, it is significantly compromised at P20. Notably, this phenotype is distinct from the synapse refinement defect previously reported for Mecp2 null mice, where synapses initially refine but then regress after the third postnatal week. We thus propose a model in which activity-induced phosphorylation of MeCP2 is critical for the proper timing of retinogeniculate synapse maturation specifically during the early postnatal period.
Project description:Mutations of MECP2 (Methyl-CpG Binding Protein 2) cause Rett Syndrome. As a chromatin associated multifunctional protein, how MeCP2 integrates external signals and regulates neuronal function remain unclear. While neuronal activity-induced phosphorylation of MeCP2 at serine 421 (S421) has been reported, the full spectrum of MeCP2 phosphorylation together with the in vivo function of such modifications are yet to be revealed. Here we report the identification of several novel MeCP2 phosphorylation sites in normal and epileptic brains from multiple species. We demonstrate that serine 80 (S80) phosphorylation of MeCP2 is critical as its mutation into alanine (S80A) in transgenic knock-in mice leads to locomotor deficits. S80A mutation attenuates MeCP2 chromatin association at several gene promoters in resting neurons and leads to transcription changes of a small number of genes. Calcium influx in neurons causes dephosphorylation at S80, potentially contributing to its dissociation from the chromatin. We postulate that phosphorylation of MeCP2 modulates its dynamic function in neurons transiting between resting and active states within neural circuits that underlie behaviors. E 15.5 Mecp2 -/y cortical neurons were infected with lentivirus expressing wild-type and S80A mutant MeCP2 at similar protein expression level. 2 biological independent samples and dye swap were used for this set (GSM367413) and replicate 2 set (GSM367414).
Project description:Disruption of the MECP2 gene leads to Rett syndrome (RTT), a severe neurological disorder with features of autism. MECP2 encodes a methyl-DNA-binding protein that is proposed to function as a transcriptional repressor, but, despite numerous studies examining neuronal gene expression in MeCP2 mutants, no coherent model has emerged for how MeCP2 regulates transcription. Here we identify a genome-wide length-dependent increase in the expression of long genes in neurons lacking MeCP2. This gene misregulation occurs in human RTT brains and correlates with onset and severity of phenotypes in Mecp2 mutant mice, suggesting that the disruption of long gene expression contributes to RTT pathology. We present evidence that MeCP2 represses long genes by binding to brain-enriched, methylated CA dinucleotides within genes and show that loss of methylated CA in the brain recapitulates gene expression defects observed in MeCP2 mutants. We find that long genes encode proteins with neuronal functions, and overlap substantially with genes that have been implicated in autism and Fragile X syndrome. Reversing the overexpression of long genes in neurons lacking MeCP2 can improve some RTT-associated cellular deficits. These findings suggest that a function of MeCP2 in the mammalian brain is to temper the expression of genes in a length-dependent manner, and that mutations in MeCP2 and possibly other autism genes may cause neurological dysfunction by disrupting the expression of long genes in the brain. MeCP2 ChIP-seq from the forebrain and cerebellum of wild-type mice.
Project description:Disruption of the MECP2 gene leads to Rett syndrome (RTT), a severe neurological disorder with features of autism. MECP2 encodes a methyl-DNA-binding protein that is proposed to function as a transcriptional repressor, but, despite numerous studies examining neuronal gene expression in MeCP2 mutants, no coherent model has emerged for how MeCP2 regulates transcription. Here we identify a genome-wide length-dependent increase in the expression of long genes in neurons lacking MeCP2. This gene misregulation occurs in human RTT brains and correlates with onset and severity of phenotypes in Mecp2 mutant mice, suggesting that the disruption of long gene expression contributes to RTT pathology. We present evidence that MeCP2 represses long genes by binding to brain-enriched, methylated CA dinucleotides within genes and show that loss of methylated CA in the brain recapitulates gene expression defects observed in MeCP2 mutants. We find that long genes encode proteins with neuronal functions, and overlap substantially with genes that have been implicated in autism and Fragile X syndrome. Reversing the overexpression of long genes in neurons lacking MeCP2 can improve some RTT-associated cellular deficits. These findings suggest that a function of MeCP2 in the mammalian brain is to temper the expression of genes in a length-dependent manner, and that mutations in MeCP2 and possibly other autism genes may cause neurological dysfunction by disrupting the expression of long genes in the brain. Bisulfite-seq from mouse cortex and cerebellum
Project description:Rett syndrome (RTT) is an X-linked neurodevelopmental disorder caused by loss-of-function heterozygous mutations of MECP2. Reactivation of the silent wild-type MECP2 allele on the inactive X chromosome (Xi) represents a promising therapeutic opportunity for female RTT patients. Here, we applied a multiplex epigenome editing approach to reactivate MECP2 on Xi. Demethylation of the MECP2 promoter by dCas9-Tet1 with target sgRNA reactivated MECP2 on Xi in RTT hESCs without detectable off-target effects at the transcriptome level. Neurons derived from methylation edited RTT hESCs reversed the smaller soma size and electrophysiological abnormalities. Insulation of the methylation edited MECP2 locus in RTT neurons by dCpf1-CTCF with target crRNA stabilized MECP2 reactivation and rescued the RTT-related neuronal defects, providing a proof-of-concept study for multiplex epigenome editing to treat RTT.