Biotin tagging of MeCP2 reveals contextual insights into the Rett syndrome transcriptome
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ABSTRACT: Mutations in MECP2 cause Rett syndrome (RTT), a X-linked neurological disorder characterized by the regressive loss of neurodevelopmental milestones and acquired intellectual disability and motor impairments. However, the cellular heterogeneity of the mammalian brain impedes our understanding of how MECP2 mutations disrupt neuronal function and contribute to RTT. In response, we developed cell type-specific biotin tagging in mice bearing RTT-associated mutations and profiled nuclear transcriptomes in WT and mutant neurons. Although individual gene expression changes are largely specific to each mutation and cell type, higher-level transcriptional features remain conserved and correlate with RTT phenotypic severity. Furthermore, subcellular RNA populations support post-transcriptional compensation as a basis for the upregulation of long genes previously reported in RTT mutant neurons. Finally, we overcame the genetic mosacism associated with female RTT mouse models and identified functionally distinct gene expression changes in neighboring WT and mutant neurons, which altogether provide key contextual insights into RTT.
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.
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.
Project description:Mutations in the methyl-DNA-binding protein MECP2 cause the neurodevelopmental disorder Rett syndrome (RTT). How MECP2 contributes to transcriptional regulation in normal and disease states is unresolved; it has been reported to be an activator and a repressor. We describe here the first integrated CUT&Tag, transcriptome, and proteome analyses using human neurons with wild-type and mutant MECP2 molecules. MECP2 occupies CpG-rich promoter-proximal regions in over four thousand genes in human neurons, including a plethora of autism risk genes, together with RNA polymerase II (Pol II). MECP2 directly interacts with Pol II, and genes occupied by both proteins showed reduced expression in neurons with MECP2 patient mutations. We conclude that MECP2 acts as a positive cofactor for Pol II gene expression at many neuronal genes that harbor CpG-islands in promoter-proximal regions, and that RTT is due, in part, to the loss of gene activity at these genes in neurons.
Project description:Mutations in the methyl-DNA-binding protein MECP2 cause the neurodevelopmental disorder Rett syndrome (RTT). How MECP2 contributes to transcriptional regulation in normal and disease states is unresolved; it has been reported to be an activator and a repressor. We describe here the first integrated CUT&Tag, transcriptome, and proteome analyses using human neurons with wild-type and mutant MECP2 molecules. MECP2 occupies CpG-rich promoter-proximal regions in over four thousand genes in human neurons, including a plethora of autism risk genes, together with RNA polymerase II (Pol II). MECP2 directly interacts with Pol II, and genes occupied by both proteins showed reduced expression in neurons with MECP2 patient mutations. We conclude that MECP2 acts as a positive cofactor for Pol II gene expression at many neuronal genes that harbor CpG-islands in promoter-proximal regions, and that RTT is due, in part, to the loss of gene activity at these genes in neurons.
Project description:Mutations in the methyl-DNA-binding protein MECP2 cause the neurodevelopmental disorder Rett syndrome (RTT). How MECP2 contributes to transcriptional regulation in normal and disease states is unresolved; it has been reported to be an activator and a repressor. We describe here the first integrated CUT&Tag, transcriptome, and proteome analyses using human neurons with wild-type and mutant MECP2 molecules. MECP2 occupies CpG-rich promoter-proximal regions in over four thousand genes in human neurons, including a plethora of autism risk genes, together with RNA polymerase II (Pol II). MECP2 directly interacts with Pol II, and genes occupied by both proteins showed reduced expression in neurons with MECP2 patient mutations. We conclude that MECP2 acts as a positive cofactor for Pol II gene expression at many neuronal genes that harbor CpG-islands in promoter-proximal regions, and that RTT is due, in part, to the loss of gene activity at these genes in neurons.
Project description:Mutations in the methyl-DNA-binding protein MECP2 cause the neurodevelopmental disorder Rett syndrome (RTT). How MECP2 contributes to transcriptional regulation in normal and disease states is unresolved; it has been reported to be an activator and a repressor. We describe here the first integrated CUT&Tag, transcriptome, and proteome analyses using human neurons with wild-type and mutant MECP2 molecules. MECP2 occupies CpG-rich promoter-proximal regions in over four thousand genes in human neurons, including a plethora of autism risk genes, together with RNA polymerase II (Pol II). MECP2 directly interacts with Pol II, and genes occupied by both proteins showed reduced expression in neurons with MECP2 patient mutations. We conclude that MECP2 acts as a positive cofactor for Pol II gene expression at many neuronal genes that harbor CpG-islands in promoter-proximal regions, and that RTT is due, in part, to the loss of gene activity at these genes in neurons.
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. Evaluation of off-target effects of dCpf1-CTCF with crRNA targeting CTCF binding flanking MECP2 locus
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:Rett syndrome (RTT) is one of the most prevalent female mental disorders. De novo mutations in methyl CpG binding protein 2 (MeCP2) are a major cause of RTT. MeCP2 regulates gene expression as a transcription regulator as well as through long-range chromatin interaction. Because MeCP2 is present on the X chromosome, RTT is manifested in a X-linked dominant manner. Investigation using murine MeCP2 null models and post-mortem human brain tissues has contributed to understanding the molecular and physiological function of MeCP2. In addition, RTT models using human induced pluripotent stem cells derived from RTT patients (RTT-iPSCs) provide novel resources to elucidate the regulatory mechanism of MeCP2. Previously, we obtained clones of female RTT-iPSCs that express either wild type or mutant MECP2 due to the inactivation of one X chromosome. Reactivation of the X chromosome also allowed us to have RTT-iPSCs that express both wild type and mutant MECP2. Using these unique pluripotent stem cells, we investigated the regulation of gene expression by MeCP2 in pluripotent stem cells by transcriptome analysis. We found that MeCP2 regulates genes encoding mitochondrial membrane proteins. In addition, loss of function in MeCP2 results in de-repression of genes on the inactive X chromosome. Furthermore, we showed that each mutation in MECP2 affects a partly different set of genes. These studies suggest that fundamental cellular physiology is affected by mutations in MECP2 from very early fetal development and that a therapeutic approach targeting to unique forms of mutant MeCP2 is needed. RNA samples from normal ESCs/iPSCs, RTT-iPSCs and MeCP2 KD iPSCs were obtained. Gene expression of those cells were analyzed.
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