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: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.
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: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 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: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:Methyl-CpG binding protein 2 (MeCP2) is a nuclear protein that binds to methylated cytosines and regulates gene expression. Normal brain function requires precise control of MeCP2 level. Loss of function mutations in the X-linked gene, MECP2 cause Rett Syndrome (RTT), a progressive neurological disorder. Increase in MeCP2 level leads to the neurological disorder MECP2 duplication syndrome (MDS). Despite the functional importance of MeCP2 in the brain, its transcriptional regulation remains poorly understood. Here, we utilized ATAC-seq in the mouse brain across development to identify five putative adult brain cis-regulatory elements (CREs) of Mecp2. We found that knocking out these CREs using CRISPR-Cas9 altered Mecp2 levels. Furthermore, two of the CREs were conserved in human, and when we delete either of these in mice, the animals show progressive neurological dysfunction. Deletion of one of the conserved CREs led to a decreased MeCP2 level and caused phenotypes similar, albeit milder, to those seen in Mecp2-null mice whereas the deletion of the second CRE led to an increased MeCP2 level and phenotypically resembled, but also milder than, MECP2 duplication mice. Deleting these two conserved CREs levels in human iPSC-derived neurons also similarly altered MECP2 levels. Taken together, our discovery of CREs that modulate Mecp2/MECP2 expression provides insight into regulation of Mecp2/MECP2 in the mouse brain and human neurons, respectively. These CREs could be candidate sites for non-coding mutations that lead to neurodevelopmental disorders characterized by partial features of RTT or MDS.
Project description:Rett syndrome is a human intellectual disability disorder that is associated with mutations in the X-linked MECP2 gene. Theepigenetic reader MeCP2 binds to methylated cytosines on the DNA and regulates chromatin organization. We have shownpreviously that MECP2 Rett syndrome missense mutations are impaired in chromatin binding and heterochromatinreorganization. Here, we performed a proteomics analysis of post-translational modifications of MeCP2 isolated from adult mousebrain. We show that MeCP2 carries various post-translational modifications, among them phosphorylation on S80 and S421, whichlead to minor changes in either heterochromatin binding kinetics or clustering. We found that MeCP2 is (di)methylated on severalarginines and that this modification alters heterochromatin organization. Interestingly, we identified the Rett syndrome mutationsite R106 as a dimethylation site. In addition, co-expression of protein arginine methyltransferases 1 and 6 lead to a decrease ofheterochromatin clustering. Altogether, we identified and validated novel modifications of MeCP2 in the brain and show that thesecan modulate its ability to bind as well as reorganize heterochromatin, which may play a role in the pathology of Rett syndrome.