The chromatin modifier CHD8 targets autism risk genes during human neurodevelopmentM-BM-
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ABSTRACT: Whole-exome sequencing studies have implicated chromatin modifiers and transcriptional regulators in autism spectrum disorder (ASD) through the identification of de novo loss of function mutations in affected individuals. Many of these genes are co-expressed in mid-fetal human cortex, suggesting ASD risk genes converge in regulatory networks that are perturbed in ASD during neurodevelopment. To elucidate such networks we mapped promoters and enhancers bound by the chromodomain helicase CHD8, which is strongly enriched in ASD-associated de novo loss of function mutations, using ChIP-seq in mid-fetal human brain, human neural stem cells (hNSCs), and embryonic mouse cortex. We find that CHD8 targets are strongly enriched for ASD risk genes that converge in ASD-associated co-expression networks in human midfetal cortex. CHD8 knockdown in hNSCs results in significant dysregulation of ASD risk genes targeted by CHD8, as well as additional genes important for neurodevelopment, including members of the Wnt/M-NM-2-catenin signaling pathway. Integration of CHD8 binding data with genetic and gene co-expression data in ASD risk models provides support for additional ASD risk genes. Together, our results suggest that loss of CHD8 function contributes to ASD through regulatory perturbation of other ASD risk genes during human cortical development. Two biological replicates for each ChIP with appropriate Input control Four biological replicates for each condition in knockdown experiments (Ctrl construct, Chd8 target C, and Chd8 target G)
Project description:CHD8, encoding Chromodomain helicase DNA binding protein 8, is a top autism spectrum disorders (ASDs) risk gene. To better understanding the molecular links between CHD8 functions and ASD, we have applied the CRISPR/Cas9 technology to knockout one copy of CHD8 in induced pluripotent stem cells (iPSCs) to mimic the loss of function status that would exist in the developing human embryo prior to neuronal differentiation. Transcriptome profiling (RNA-seq) in neural progenitors and early differentiating neurons revealed that CHD8 hemizygosity (CHD8+/-) affected the expression of several thousands of genes, enriched for functions of neural development, β-catenin/Wnt signaling, extracellular matrix, and skeletal system development. Moreover, CHD8 regulates multiple genes implicated in ASD, schizophrenia and genes associated with brain volume. iPSCs derived from a healthy subject were transduced with CRISPR/Cas9 vectors with single guide RNA sequences to target the N-terminal of CHD8 protein to generate truncated mutation seach of the two target sequences. Two clones, one with a 2-bp (KO1) and the other with a 10-bp (KO2) heterozygous deletion were found.The CHD8+/- iPSC lines were used to generate NPCs and early differentiating neurons for RNA-seq analysis, together with samples prepared from the parental clones, for a total of 8 samples (two biological replicates of wild-type (WT) and CHD8+/- at two neurodevelopmental stages).
Project description:Whole-exome sequencing studies have implicated chromatin modifiers and transcriptional regulators in autism spectrum disorder (ASD) through the identification of de novo loss of function mutations in affected individuals. Many of these genes are co-expressed in mid-fetal human cortex, suggesting ASD risk genes converge in regulatory networks that are perturbed in ASD during neurodevelopment. To elucidate such networks we mapped promoters and enhancers bound by the chromodomain helicase CHD8, which is strongly enriched in ASD-associated de novo loss of function mutations, using ChIP-seq in mid-fetal human brain, human neural stem cells (hNSCs), and embryonic mouse cortex. We find that CHD8 targets are strongly enriched for ASD risk genes that converge in ASD-associated co-expression networks in human midfetal cortex. CHD8 knockdown in hNSCs results in significant dysregulation of ASD risk genes targeted by CHD8, as well as additional genes important for neurodevelopment, including members of the Wnt/β-catenin signaling pathway. Integration of CHD8 binding data with genetic and gene co-expression data in ASD risk models provides support for additional ASD risk genes. Together, our results suggest that loss of CHD8 function contributes to ASD through regulatory perturbation of other ASD risk genes during human cortical development.
Project description:We used cerebral organoids generated from wildtype and CHD8 +/- human ES cells to study the effects of CHD8, one of the top ASD risk genes, on early cortical development. CHD8 +/- hESC were generated using the CRISPR/Cas9 system to create a deletion within the helicase domain. Cerebral organoids were generated according to the protocol from Lancaster et al 2013 with minor modifications.
Project description:Autism spectrum disorder (ASD) is a common and etiologically heterogeneous neurodevelopmental disorder. Although many genetic causes have been identified (>200 ASD-risk genes), no single gene mutation accounts for >1% of all ASD cases. A role for epigenetic mechanisms in ASD etiology is supported by the fact that many ASD-risk genes function as epigenetic regulators and evidence that epigenetic dysregulation can interrupt normal brain development. To investigate the epigenome in patients with ASD, genome-wide DNA methylation (DNAm) was assessed using the Illumina Infinium HumanMethylation450K array in blood from individuals with ASD of heterogeneous, undefined etiology (n=52) and individuals with 16p11.2 deletions (16p11.2del, n=9) or pathogenic variants in the chromatin modifier CHD8 (CHD8+/-, n=7), two of the most common genomic variants conferring increased risk for ASD. DNAm patterns did not clearly distinguish heterogeneous ASD cases from controls. However, the homogeneous genetically-defined 16p11.2del and CHD8+/- subgroups each exhibited unique DNAm signatures that distinguished 16p11.2del or CHD8+/- individuals from both heterogeneous ASD and control groups with high sensitivity and specificity. These signatures also classified additional 16p11.2del (n=9) and CHD8 (n=9) variants as pathogenic or benign. Our findings that DNAm alterations in each signature targets unique genes in biological pathways relevant to neural development support their functional relevance. Furthermore, genes identified in our CHD8+/- DNAm signature in blood overlapped differentially expressed genes in CHD8+/- human-induced pluripotent cell-derived neurons and cerebral organoids from independent studies. Our study constitutes a novel approach for ASD molecular classification that elucidates the vital cross-talk between genetics and epigenetics in the etiology of ASD.
Project description:Truncating mutations of CHD8, encoding a chromodomain helicase, and of many other genes with diverse functions, are strong-effect risk factors for autism spectrum disorder (ASD), suggesting multiple mechanisms of pathogenesis. We explored the transcriptional networks that CHD8 regulates in neural progenitor cells (NPCs) by reducing its expression and then integrating transcriptome sequencing (RNA-seq) with genome-wide CHD8 binding (ChIP-seq). Suppressing CHD8 to levels comparable with loss of a single allele caused altered expression of 1,756 genes, 64.9% of which were up-regulated. CHD8 showed widespread binding to chromatin, with 7,324 replicated sites that marked 5,658 genes. Integration of these data suggests that a limited array of direct regulatory effects of CHD8 produced a much larger network of secondary expression changes. Genes indirectly down-regulated (i.e., without CHD8 binding sites) reflect pathways involved in brain development, including synapse formation, neuron differentiation, cell adhesion, and axon guidance, whereas CHD8-bound genes are strongly associated with chromatin modification and transcriptional regulation. Genes associated with ASD were strongly enriched among indirectly down-regulated loci (pM-BM- =M-BM- 1.01x10-9) and CHD8-bound genes (p = 4.34x10-3), which align with previously identified co-expression modules during fetal development. We also find an intriguing enrichment of cancer related gene-sets among CHD8-bound genes (p < 1.9x10-11). In vivo suppression of chd8 in zebrafish produced macrocephaly comparable to that of humans with inactivating mutations. These data indicate that heterozygous disruption of CHD8 precipitates a network of gene expression changes involved in neurodevelopmental pathways in which many ASD-associated genes may converge on shared mechanisms of pathogenesis. ChIP-seq for CHD8 using three different antibodies, and the related protein CHD7, in human iPSC-derived NPCs treated with shRNA targeting GFP (which were used as control cells for an shRNA knockdown RNA-seq experiment that was part of the overall study)
Project description:Truncating mutations of CHD8, encoding a chromodomain helicase, and of many other genes with diverse functions, are strong-effect risk factors for autism spectrum disorder (ASD), suggesting multiple mechanisms of pathogenesis. We explored the transcriptional networks that CHD8 regulates in neural progenitor cells (NPCs) by reducing its expression and then integrating transcriptome sequencing (RNA-seq) with genome-wide CHD8 binding (ChIP-seq). Suppressing CHD8 to levels comparable with loss of a single allele caused altered expression of 1,756 genes, 64.9% of which were up-regulated. CHD8 showed widespread binding to chromatin, with 7,324 replicated sites that marked 5,658 genes. Integration of these data suggests that a limited array of direct regulatory effects of CHD8 produced a much larger network of secondary expression changes. Genes indirectly down-regulated (i.e., without CHD8 binding sites) reflect pathways involved in brain development, including synapse formation, neuron differentiation, cell adhesion, and axon guidance, whereas CHD8-bound genes are strongly associated with chromatin modification and transcriptional regulation. Genes associated with ASD were strongly enriched among indirectly down-regulated loci (p = 1.01x10-9) and CHD8-bound genes (p = 4.34x10-3), which align with previously identified co-expression modules during fetal development. We also find an intriguing enrichment of cancer related gene-sets among CHD8-bound genes (p < 1.9x10-11). In vivo suppression of chd8 in zebrafish produced macrocephaly comparable to that of humans with inactivating mutations. These data indicate that heterozygous disruption of CHD8 precipitates a network of gene expression changes involved in neurodevelopmental pathways in which many ASD-associated genes may converge on shared mechanisms of pathogenesis. RNA-seq in NPCs treated with shRNAs targeting CHD8. For controls, NPCs were treated with shRNAs targeting GFP and LacZ. Infection and sequencing was carried out in two separate batches, with one GFP and one LacZ sample in each batch. All samples were sequenced in two technical replicates.
Project description:Disruptive variants in the chromodomain helicase CHD8, which acts as a transcriptional regulator during neurodevelopment, are strongly associated with risk for autism spectrum disorder (ASD). Loss of CHD8 function is hypothesized to perturb gene regulatory networks in the developing brain, thereby contributing to ASD etiology. However, insight into the cell type-specific transcriptional effects of CHD8 loss of function remains limited. We used single-cell and single-nucleus RNA-sequencing to globally profile gene expression and identify dysregulated genes in the embryonic and juvenile wild type and Chd8+/− mouse cortex, respectively. Chd8 and other ASD risk-associated genes showed a convergent expression trajectory that was largely conserved between the mouse and human developing cortex, increasing from the progenitor zones to the cortical plate. Genes associated with risk for neurodevelopmental disorders and genes involved in neuron projection development, chromatin remodeling, signaling, and migration were dysregulated in Chd8+/− embryonic day (E) 12.5 radial glia. Genes implicated in synaptic organization and activity were dysregulated in Chd8+/− postnatal day (P) 25 deep- and upper-layer excitatory neurons, suggesting a delay in synaptic maturation or impaired synaptogenesis due to CHD8 loss of function. Our findings reveal a complex pattern of transcriptional dysregulation in Chd8+/− developing cortex, potentially with distinct biological impacts on progenitors and maturing neurons in the excitatory neuronal lineage.
Project description:Disruptive variants in the chromodomain helicase CHD8, which acts as a transcriptional regulator during neurodevelopment, are strongly associated with risk for autism spectrum disorder (ASD). Loss of CHD8 function is hypothesized to perturb gene regulatory networks in the developing brain, thereby contributing to ASD etiology. However, insight into the cell type-specific transcriptional effects of CHD8 loss of function remains limited. We used single-cell and single-nucleus RNA-sequencing to globally profile gene expression and identify dysregulated genes in the embryonic and juvenile wild type and Chd8+/− mouse cortex, respectively. Chd8 and other ASD risk-associated genes showed a convergent expression trajectory that was largely conserved between the mouse and human developing cortex, increasing from the progenitor zones to the cortical plate. Genes associated with risk for neurodevelopmental disorders and genes involved in neuron projection development, chromatin remodeling, signaling, and migration were dysregulated in Chd8+/− embryonic day (E) 12.5 radial glia. Genes implicated in synaptic organization and activity were dysregulated in Chd8+/− postnatal day (P) 25 deep- and upper-layer excitatory neurons, suggesting a delay in synaptic maturation or impaired synaptogenesis due to CHD8 loss of function. Our findings reveal a complex pattern of transcriptional dysregulation in Chd8+/− developing cortex, potentially with distinct biological impacts on progenitors and maturing neurons in the excitatory neuronal lineage.
Project description:Disruptive variants in the chromodomain helicase CHD8, which acts as a transcriptional regulator during neurodevelopment, are strongly associated with risk for autism spectrum disorder (ASD). Loss of CHD8 function is hypothesized to perturb gene regulatory networks in the developing brain, thereby contributing to ASD etiology. However, insight into the cell type-specific transcriptional effects of CHD8 loss of function remains limited. We used single-cell and single-nucleus RNA-sequencing to globally profile gene expression and identify dysregulated genes in the embryonic and juvenile wild type and Chd8+/− mouse cortex, respectively. Chd8 and other ASD risk-associated genes showed a convergent expression trajectory that was largely conserved between the mouse and human developing cortex, increasing from the progenitor zones to the cortical plate. Genes associated with risk for neurodevelopmental disorders and genes involved in neuron projection development, chromatin remodeling, signaling, and migration were dysregulated in Chd8+/− embryonic day (E) 12.5 radial glia. Genes implicated in synaptic organization and activity were dysregulated in Chd8+/− postnatal day (P) 25 deep- and upper-layer excitatory neurons, suggesting a delay in synaptic maturation or impaired synaptogenesis due to CHD8 loss of function. Our findings reveal a complex pattern of transcriptional dysregulation in Chd8+/− developing cortex, potentially with distinct biological impacts on progenitors and maturing neurons in the excitatory neuronal lineage.
Project description:Mutations in the gene encoding the chromatin remodeler CHD8 are a highly penetrant risk factor for autism spectrum disorder (ASD). Although cerebellar abnormalities have been involved in ASD pathogenesis, the underlying mechanisms of CHD8 in the regulation of cerebellar function has remained unknown, however. Here we show that the cerebellar granule neurons–specific deletion of Chd8 manifests reduced proliferation and differentiation of granule neuron progenitors, leading to cerebellar hypoplasia and motor coordination defects in mice. CHD8 was found to regulate the expression of neuronal genes and to be required for maturation of cerebellar granule neurons. Furthermore, we found that CHD8 is preferentially bound to promoter regions and is necessary for modulation of local chromatin accessibilities at promoter regions of active gene. Our results thus uncover a critical role for CHD8 in cerebellar development and have important implications for understanding the cerebellar contributions to ASD pathogenesis.