Project description:Truncating CHD8 mutations are amongst the highest confidence risk factors for autism spectrum disorders (ASD) identified to date. Here, we report that Chd8 heterozygous mice display increased brain size, motor delay, hypertelorism, pronounced hypoactivity, and anomalous responses to social stimuli. Whereas gene expression in the neocortex is only mildly affected at mid gestation, over 600 genes are differentially expressed in the early postnatal neocortex. Genes involved in cell adhesion and axon guidance are particularly prominent amongst the downregulated transcripts. Resting-state functional MRI identified increased synchronized activity in corticohippocampal and auditory-parietal networks in Chd8 heterozygous mutant mice, implicating altered connectivity as a potential mechanism underlying the behavioral phenotypes. Together, these data suggest that altered brain growth and diminished expression of important neurodevelopmental genes that regulate long-range brain wiring are followed by distinctive anomalies in functional brain connectivity in Chd8 +/− mice. Human imaging studies have reported altered functional connectivity in ASD patients, with long-range under-connectivity seemingly more frequent. Our data suggest that CHD8 haploinsufficiency represents a specific subtype of ASD where neuropsychiatric symptoms are underpinned by long-range over-connectivity.
Project description:Heterozygous CHD8 mutations are associated with autism and macrocephaly with high penetrance in the human population. The reported mutations may have loss-of-function (haploinsufficient), hypomorphic or dominant negative effects on protein function. To determine the effects of reducing CHD8 protein function below haploinsufficient levels on brain development, we established a Chd8 allelic series in the mouse. Chd8 heterozygous mice exhibited relatively subtle brain overgrowth and little gene expression changes in the embryonic neocortex. In comparison, mild Chd8 hypomorphs displayed significant postnatal lethality, with surviving animals exhibiting more pronounced brain hyperplasia, and significantly altered expression of over 2000 genes. Autism-associated genes were downregulated and neural progenitor proliferation genes upregulated. Severe Chd8 hypomorphs displayed even greater transcriptional dysregulation, affecting genes and pathways that largely overlapped with those dysregulated in the mild hypomorphs. By contrast, homozygous, conditional deletion of Chd8 in early neuronal progenitors resulted in the induction of p53 target genes, cell cycle exit, apoptosis and pronounced brain hypoplasia. Intriguingly, increased progenitor proliferation in hypomorphs was primarily restricted to TBR2+ intermediate progenitors, suggesting critical roles for CHD8 in regulating the expansion of this population. Given the importance of these progenitors in human cortical growth, this observation suggests that human brain development might be more sensitive to CHD8 deficiency than the mouse. We conclude that brain development is acutely sensitive to CHD8 dosage and that the varying sensitivities of different progenitor populations and cellular processes to CHD8 dosage can result in non-linear effects on gene transcription and brain growth.
Project description:Hundreds of genes have been associated with autism spectrum disorder (ASD), including loss-of-function mutations in chromodomain helicase DNA binding protein 8 (Chd8). Environmental factors also are implicated in autism risk and have the potential to exacerbate phenotypes in genetically sensitized backgrounds. Here we investigate transcriptional and behavioral phenotypes in a Chd8 haploinsufficient (Chd8V986*/+) mouse line exposed to the pesticide deltamethrin (DM) from conception to postnatal day 22. Vehicle-exposed Chd8V986*/+ mice displayed ASD-associated phenotypes, including anxiety-like behavior and altered sociability, replicating a previous study with this mouse line. A core set of genes was altered in Chd8V986*/+ mice at multiple ages, including Usp11, Wars2, Crlf2, and Eglf6, and proximity ligation data indicated direct binding of CHD8 to the 5’ region of these genes. Moreover, a neurodegenerative transcriptional phenotype was apparent in 12 and 18 month old Chd8V986*/+ mice. Following DM exposure, the mutant mice displayed an exacerbated phenotype in the elevated plus maze, and genes associated with vascular endothelial cells were downregulated in the cerebral cortex of older Chd8V986*/+ animals. Our study reveals a gene x environment interaction with a Chd8 haploinsufficient mouse line and points to the importance of investigating phenotypes in ASD animal models across the lifespan.
Project description:We examined the impact of germline heterozygous frameshift Chd8 mutation on neurodevelopment in mice. Adult Chd8+/del5 mice exhibited cognitive impairment correlated with increased cerebral cortex, hippocampus, and amygdala volume, but displayed normal social interactions and no repetitive behaviors. Network analysis of neurodevelopmental gene expression revealed widespread transcriptional changes in Chd8+/del5 mice across pathways disrupted in neurodevelopmental disorders, including neurogenesis, synaptic processes, and neuroimmune signaling. Among gene co-expression networks, we identified a module with peak expression in early brain development that featured dysregulation of genes enriched for promoter binding by Chd8 and associated with RNA processing, chromatin remodeling, and cell cycle. We validated increased neuronal proliferation and splicing alterations during Chd8+/del5 brain development. Our results show that Chd8+/del5 mice exhibit neurodevelopmental changes paralleling humans with CHD8 mutations and highlight widespread pathological consequences of Chd8 haploinsufficiency.
Project description:Chromodomain helicase DNA-binding protein 8 (CHD8), now considered a master transcriptional regulator for autism, is mutated in more autism probands (0.45%) than any other gene. We generated mutant mice with a human loss-of-function (LOF) mutation in Chd8 (Val986X, henceforth referred to as V986*). Heterozygous mutant mice (Chd8V986*/+) display features of ASD, including anxiety like behavior and macrocephaly. Perturbation of CHD8 also recapitulates increased sociability found in other CHD8 mutant animal models. Our study expands previously identified knowledge of CHD8 mutant mouse models by examining temporal alterations in the transcriptional profile of mouse cortical tissue resulting from a reduction in CHD8 expression. Dysregulation of major cellular processes uniquely includes a reduction in neuronal signaling, focal adhesion, and synaptic function genes early in development, that increase in expression into adulthood. At 12 months, heterozygous mice display decreased endoplasmic reticulum (ER) stress, decreased unfolded protein response (UPR) and increased MET signaling likely resulting from a combination of reduced CHD8 expression and reflecting an altered network structure formed early in development. These data provide greater insight into the role of CHD8 in brain function and how mutations in the gene can contribute to ASD etiology.
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:In this study, we developed two isogenic haploinsufficient CHD8+/– human embryonic stem cell lines (hESCs) that we induced into neurons (iNs) upon doxycycline-inducible overexpression of Neurogenin 2 and Neurogenin 1 (NEUROG2/1), and we profiled the key molecular alterations in chromatin accessibility (ATAC-seq) and expression (RNA-seq) resulting from the loss of CHD8, the most recurrently mutated gene in autism spectrum disorders (ASD).
Project description:In this study, we developed two isogenic haploinsufficient CHD8+/– human embryonic stem cell lines (hESCs) that we induced into neurons (iNs) upon doxycycline-inducible overexpression of Neurogenin 2 and Neurogenin 1 (NEUROG2/1), and we profiled the key molecular alterations in chromatin accessibility (ATAC-seq) and expression (RNA-seq) resulting from the loss of CHD8, the most recurrently mutated gene in autism spectrum disorders (ASD).
Project description:Disruptive mutations in the chromodomain helicase DNA binding protein 8 (CHD8) have been recurrently associated with Autism Spectrum Disorders (ASD). Here we investigated how chromatin reacts to CHD8 suppression by analyzing a panel of histone modifications in induced pluripotent stem cell-derived neural progenitors. CHD8 suppression led to significant reduction (47.82%) in histone H3K36me3 peaks at gene bodies, particularly impacting on transcriptional elongation chromatin states. H3K36me3 reduction specifically affects highly expressed, CHD8-bound genes and correlates with altered alternative splicing patterns of 408 genes implicated in “regulation of RNA splicing”, “mRNA catabolic process”. Interestingly, mass-spectrometry analysis uncovered a novel interaction between CHD8 and the splicing regulator Heterogeneous Nuclear Ribonucleoprotein L (hnRNPL), providing the first mechanistic insights to explain CHD8-suppression splicing phenotype, partially implicating SETD2, H3K36me3 methyltransferase. In summary, our results point toward broad molecular consequences of CHD8 suppression, entailing altered histone deposition/maintenance and RNA processing regulation as important regulatory processes in ASD.