Project description:To investigate the molecular basis for the B cell developmental arrest in Pax5R31Q/– mice, we performed RNA-sequencing (RNA-seq) with ex vivo sorted Pax5+/+ and Pax5R31Q/– pro-B cells. We identified Pax5-activated and Pax5-repressed genes that were no longer properly regulated by the Pax5-R31Q protein in Pax5R31Q/– pro-B cells. Notably, these genes were only a subset of the activated and repressed genes identified by comparing Pax5+/+ and Pax5–/– pro-B cells, which raised the question whether binding of the Pax5-R31Q protein may be selectively lost at the subset of deregulated genes in Pax5R31Q/– pro-B cells. By using a Pax5 paired domain antibody for chromatin immunoprecipitation coupled with deep sequencing (ChIP-seq) of short-term cultured Pax5+/+ and Pax5R31Q/– pro-B cells, we identified all associated Pax5 binding sites. Common Pax5 peaks had a similar Pax5-binding density in contrast to the strong binding difference observed at the unique peaks present in Pax5+/+ pro-B cells. To investigate a correlation between the loss of Pax5 binding and gene expression, we focused our analysis on Pax5 peaks in the TSS region of activated genes. We systematically investigated the correlation between loss of Pax5 binding at the TSS and down-regulation of gene expression in Pax5R31Q/– pro-B cells. The ratio of Pax5 binding between Pax5R31Q/– and Pax5+/+ pro-B cells at the TSS of these activated genes was significantly reduced compared to that of expressed non-regulated genes. We next explored whether the Pax5-binding difference at the TSS also correlated with the magnitude of gene expression difference. The loss of Pax5 binding at the TSS also correlated with the degree of expression change in Pax5R31Q/– pro-B cells compared to Pax5+/+ pro-B cells. We conclude therefore that the selective DNA-binding of Pax5-R31Q is responsible for the observed gene expression differences in Pax5R31Q/– pro-B cells.
Project description:To assess the clinical impact of splice-altering noncoding mutations in autism spectrum disorder (ASD), we used a deep learning framework (SpliceAI) to predict the splice-altering potential of de novo mutations in 3,953 individuals with ASD from the Simons Simplex Collection. To validate these predictions, we selected 36 individuals that harbored predicted de-novo cryptic splice mutations; each individual represented the only case of autism within their immediate family. We obtained peripheral blood-derived lymphoblastoid cell lines (LCLs) and performed high-depth mRNA sequencing (approximately 350 million 150 bp single-end reads per sample). We used OLego to align the reads against a reference created from hg19 by substituting de novo variants of each individual with the corresponding alternate allele.
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: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: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:Chromosomal abnormalities have been identified in some individuals with Autism Spectrum Disorder (ASD), but their full etiologic role is unknown. Submicroscopic copy number variation (CNV) represents a considerable source of genetic variation in the human genome that contributes to phenotypic differences and disease susceptibility. To explore the contribution CNV imbalances in ASD, we genotyped unrelated ASD index cases using the Affymetrix GeneChip® 500K single nucleotide polymorphism (SNP) mapping array. Keywords: Whole Genome Mapping SNP Genotyping Array
Project description:Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by social communication deficits and repetitive behaviors. MicroRNAs (miRNAs) have been recently recognized as potential biomarkers of ASD as they are dysregulated in various tissues of individuals with ASD. However, it remains unclear whether miRNA expression is altered in individuals with high-functioning ASD. Here, we investigated the miRNA expression profile in peripheral blood from adults with high-functioning ASD, and age and gender-matched healthy controls. Our findings may provide insights regarding the molecular clues for recognizing high-functioning ASD.
Project description:Autism spectrum disorders (ASD) are a group of genetic disorders often overlapping with other neurological conditions. We previously described abnormalities in the branched chain amino acid (BCAA) catabolic pathway as a cause of ASD. Here we show that the solute carrier transporter 7a5 (SLC7A5), a large neutral amino acid transporter localized at the blood brain barrier (BBB), has an essential role in maintaining normal levels of brain BCAAs. In mice, deletion of Slc7a5 from the endothelial cells of the BBB leads to decreased levels of brain BCAAs, abnormal mRNA translation and severe neurological abnormalities. Furthermore, we identified several patients with autistic traits and motor delay carrying deleterious homozygous mutations in the SLC7A5 gene. Finally, we demonstrate that BCAA intracerebroventricular administration ameliorates abnormal behaviors in adult mutant mice. Our data elucidate a neurological syndrome defined by SLC7A5 mutations and support an essential role for the BCAA in human brain function.