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:CHD8 (chromodomain helicase DNA binding protein 8), which codes for a member of the CHD family of ATP-dependent chromatin-remodeling factors, is the most commonly mutated gene in autism spectrum disorders (ASD) identified in exome-sequencing studies. Loss of function mutations in the gene have also been found in schizophrenia (SZ) and intellectual disabilities, and affects cancer cell proliferation. To better understanding the molecular links between CHD8 functions and ASD, we have applied the CRISPR/Cas9 technology to knockout (KO) one copy of CHD8 in induced pluripotent stem cells (iPSCs) and build cerebral organoids, a model for the developing telencephalon. RNA-seq was carried out on KO organoids (CHD8+/-) and isogenic controls (CHD8+/+). Differentially expressed genes (DEGs) revealed an enrichment of genes involved in neurogenesis, forebrain development, Wnt/β-catenin signaling and axonal guidance. The SZ and bipolar disorder (BD) candidate gene TCF4 was significantly upregulated. Our CHD8 KO DEGs were significantly overlapped with those found in a transcriptome analysis using cerebral organoids derived from a family with idiopathic ASD and another transcriptome study using iPS cell-derived neurons from patients with BD, a condition characterized in a subgroup of patients by dysregulated WNT/β-catenin signaling. Overall, the findings show that distinct ASD, SZ and BD candidate genes converge on common molecular targets - an important consideration for developing novel therapeutics in genetically heterogeneous complex traits.
Project description:Chromodomain helicase DNA-binding 8 (CHD8) is one of the most frequently mutated genes causative of autism spectrum disorder (ASD). While its phenotypic spectrum often encompasses macrocephaly and hence implicates cortical abnormalities in this form of ASD, the neurodevelopmental impact of human CHD8 haploinsufficiency remains unexplored. Here we combined human cerebral organoids and single cell transcriptomics to define the effect of ASD-linked CHD8 mutations on human cortical development. We found that CHD8 haploinsufficiency causes a major disruption of neurodevelopmental trajectories with an accelerated generation of inhibitory neurons and a delayed production of excitatory neurons alongside the ensuing protraction of the proliferation phase. This imbalance may contribute to the significant enlargement of cerebral organoids in line with the macrocephaly observed in patients with CHD8 mutations. By adopting an isogenic design of patient-specific mutations and mosaic cerebral organoids, we define genotype-phenotype relationships and uncover their cell-autonomous nature. Finally, our results assign different CHD8-dependent molecular defects to particular cell types, pointing to an abnormal and extended program of proliferation and alternative splicing specifically affected in, respectively, the radial glial and immature neuronal compartments. By identifying temporally restricted cell-type specific effects of human CHD8 mutations, our study uncovers developmental alterations as reproducible endophenotypes for neurodevelopmental disease modelling.
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:Single cell ATAC-seq (scATAC-seq) was performed on bonobo induced pluripotent stem cells (iPSC) derived cerebral organoids. scATAC-seq was performed on day 60 (2 months old cerebral organoid) and day 120 (4 months old cerebral organoid).
Project description:Induced pluripotent stem cell (iPSC) derived organoid systems provide models to study human organ development. Single-cell transcriptome sequencing enables highly-resolved descriptions of cell state heterogeneity within these systems and computational methods can reconstruct developmental trajectories. However, new approaches are needed to directly measure lineage relationships in these systems. Here we establish an inducible dual channel lineage recorder, iTracer, that couples reporter barcodes, inducible CRISPR/Cas9 scarring, and single-cell transcriptomics to analyze state and lineage relationships in iPSC-derived systems. This data set include the iTracer data of 12 cerebral organoids.