Project description:Autism spectrum disorder (ASD) and mental retardation (MR) represent clinically distinct neurodevelopmental disorders with a complex genetic etiology. Using microarrays we identified de novo copy number variations in the SHANK2 synaptic scaffolding gene in two unrelated ASD and MR patients; DNA sequencing of SHANK2 revealed additional variants including a de novo nonsense mutation and 7 rare inherited changes. Our findings further link common genes between ASD and intellectual disability.
Project description:Heterozygous loss-of-function mutations in the synaptic scaffolding gene SHANK2 are strongly associated with autism spectrum disorder (ASD). To investigate their effect on synaptic connectivity, we generated cortical neurons from induced pluripotent stem cells (iPSC) derived from neurotypic and ASD-affected donors. We developed Sparse coculture for Connectivity (SparCon) assays where SHANK2 and control neurons were differentially labeled and sparsely seeded together on a lawn of unlabeled control neurons. We observed striking increases in total synapse number and dendrite complexity. Dendrite length increases were exacerbated by IGF1 or BDNF treatment. Increased excitatory synapse function in haploinsufficient SHANK2 neurons was phenocopied in gene-edited knockout SHANK2 neurons. Gene correction of an ASD SHANK2 mutation rescued excitatory synapse function supporting a role for SHANK2 as a negative regulator of connectivity in developing human neurons. The transcriptome in these isogenic SHANK2 neurons was deeply perturbed in synaptic and plasticity gene sets and ASD gene modules, and activity dependent dendrite extension was defective. Our unexpected findings provide evidence for hyperconnectivity and profoundly altered transcriptome in SHANK2 neurons derived from ASD subjects.
Project description:Shank2 is an abundant postsynaptic scaffolding protein known to regulate excitatory synaptic assembly and function and is implicated in autism spectrum disorders (ASD). Whereas patient Shank2 mutations in autistic individuals are heterozygous, Shank2 functions studied in mice have mainly relied on the results from homozygous mutant mice, largely because of relatively strong synaptic and behavioral phenotypes. Moreover, although synaptic changes at juvenile and adult Shank2-mutant mice seem to be largely similar, it remains unclear whether there are any age-dependent changes across these stages at the molecular level. To address these questions, we attempted RNA-Seq analyses of the transcriptomes in the prefrontal cortex of both heterozygous and homozygous Shank2-mutant mice lacking exons 6 and 7 at juvenile and adult stages. The results indicate that heterozygous, but not homozygous, juvenile Shank2-mutant mice show strong transcriptomic changes that promote excitatory synaptic transmission and suppress ASD-related gene expressions. In contrast, adult Shank2-mutant mice show largely similar and dosage-dependent transcriptomic changes.
Project description:Gene expression in blood of children with autism spectrum disorder (ASD) was studied. Transcriptional profiles were compared with age and gender matched, typically developing children from the general population (GP) or IQ matched children with mental retardation or developmental delay (MR/DD). Experiment Overall Design: Transcriptional profiles were compared with age and gender matched, typically developing children from the general population (GP) or IQ matched children with mental retardation or developmental delay (MR/DD)
Project description:Gene expression in blood of children with autism spectrum disorder (ASD) was studied. Transcriptional profiles were compared with age and gender matched, typically developing children from the general population (GP) or IQ matched children with mental retardation or developmental delay (MR/DD). Keywords: autism analysis
Project description:Shank2 is an abundant excitatory postsynaptic scaffolding protein implicated in neurodevelopmental disorders, including autism spectrum disorders (ASD), intellectual disability, developmental delay, and schizophrenia. Shank2-mutant mice with a homozygous deletion of exons 6 and 7 (Shank2-HM mice) show ASD-like behavioral deficits and altered synaptic functions, although little is known about how different brain regions contribute to Shank2-mutant phenotypes. Here we attempted transcriptomic analyses of the prefrontal cortex, hippocampus, and striatum in adult Shank2-heterozygous/HT and Shank2-homozygous/HM mice. The mutant cortex, hippocampus, and striatum displayed distinct sets of differentially expressed genes associated with neuronal and synaptic functions in a gene dosage-differential manner. Gene set enrichment analyses of cortical Shank2-HT transcripts revealed increased synaptic gene expression and transcriptomic changes that are opposite to those observed in ASD (reverse-ASD), whereas cortical Shank2-HM transcripts displayed decreased synaptic gene expression and ASD-like transcriptomic patterns. The hippocampal Shank2-HT transcripts displayed minimally altered synaptic gene expression and mixed ASD-like and reverse-ASD patterns, whereas the Shank2-HM-hippocampus showed increased synaptic gene expression and reverse-ASD patterns. The striatal Shank2-HT/HM transcriptomes were largely similar to the hippocampal transcriptomes, although the main changes were observed in cell-type-specific genes, unlike the hippocampal changes mainly involving ASD-related/risk genes. These results indicate that heterozygous and homozygous Shank2 deletions in mice lead to brain region- and gene dosage-differential transcriptomic changes.
Project description:Fragile X syndrome (FXS), caused by mutations in fragile X mental retardation 1 gene (FMR1), is a prevailing genetic disorder of intellectual disability and autism. Analysis of transcriptome outcome (differentially expressed genes between WT and Fmr1 KO hippocampal neuron) associated with FXS reveal promising value of gene signature-based computation in repurposing drugs for potential practical treatment.
Project description:Heterozygous loss-of-function mutations in the synaptic scaffolding gene SHANK2 are strongly associated with autism spectrum disorder (ASD). To investigate their effect on synaptic connectivity, we generated cortical neurons from induced pluripotent stem cells (iPSC) derived from neurotypic and ASD-affected donors. We developed Sparse coculture for Connectivity (SparCon) assays where SHANK2 and control neurons were differentially labeled and sparsely seeded together on a lawn of unlabeled control neurons. We observed striking increases in dendrite length, dendrite complexity, total synapse number, and frequency of spontaneous excitatory postsynaptic currents. These findings were phenocopied in gene-edited homozygous SHANK2 knockout cells and rescued by gene correction of an ASD SHANK2 muation, supporting a role for SHANK2 as a regulator of connectivity in developing human neurons. Dendrite length increases were exacerbated by IGF1, TG003, or BDNF, and suppressed by DHPG treatment. The transcriptome in these isogenic SHANK2 neurons was deeply perturbed in synapse, plasticity, and neuronal morphogenesis gene sets and ASD gene modules, and activity-dependent dendrite extension was impaired. Our unexpected findings provide evidence for hyperconnectivity and profoundly altered transcriptome in SHANK2 neurons derived from ASD subjects.
| EGAS00001003436 | EGA
Project description:Brain somatic mutations associated with autism spectrum disorder