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.
Project description:Activity-dependent neuroprotective protein (ADNP), essential for brain formation, is a frequent autism spectrum disorder (ASD)-mutated gene. ADNP associates with microtubule end binding proteins (EBs) through its SxIP motif, to regulate dendritic spine formation and brain plasticity. Here, we reveal SKIP, a novel 4 amino acid peptide representing an EB-binding site, as a replacement therapy in an outbred Adnp-deficient mouse model. We discovered, for the first time, axonal transport deficits in Adnp+/- mice (measured by manganese-enhanced magnetic resonance imaging), with significant male-female differences. Furthermore, the Adnp+/- mice exhibited impaired hippocampal expression of key ASD-linked genes including the serotonin transporter (Slc6a4), the calcium channel (VDCC) and the autophagy regulator, BECN1 (Beclin1), in a sex-dependent manner. RNA-seq evaluations corroborated, in part, immunohistochemical and functional results. Intranasal SKIP treatment normalized social memory in 8-9-month-old Adnp+/--treated mice to placebo-control levels, while protecting axonal transport and ameliorating changes in ASD-like gene expression. SKIP presents a novel lead compound for ASD drug development, a prevalent unmet medical need.
Project description:Autism spectrum disorder (ASD) is a disorder of brain development believed, in most cases, to be of genetic origin. We use induced pluripotent stem cells (iPSCs)-derived 3-dimensional neural cultures (organoids) in patients with ASD and macrocephaly to investigate neurodevelopmental alterations that cause this form of ASD. By using transcriptome analyses, we identified modules of co-expressed genes significantly upregulated in ASD patients compared to non-ASD first-degree family members.
Project description:Autism spectrum disorder (ASD) is a common, highly heritable neuro-developmental condition characterized by marked genetic heterogeneity. Thus, a fundamental question is whether autism represents an etiologically heterogeneous disorder in which the myriad genetic or environmental risk factors perturb common underlying molecular pathways in the brain. Here, we demonstrate consistent differences in transcriptome organization between autistic and normal brain by gene co-expression network analysis. Remarkably, regional patterns of gene expression that typically distinguish frontal and temporal cortex are significantly attenuated in the ASD brain, suggesting abnormalities in cortical patterning. We further identify discrete modules of co-expressed genes associated with autism: a neuronal module enriched for known autism susceptibility genes, including the neuronal specific splicing factor A2BP1/FOX1, and a module enriched for immune genes and glial markers. Using high-throughput RNA-sequencing we demonstrate dysregulated splicing of A2BP1-dependent alternative exons in ASD brain. Moreover, using a published autism GWAS dataset, we show that the neuronal module is enriched for genetically associated variants, providing independent support for the causal involvement of these genes in autism. In contrast, the immune-glial module showed no enrichment for autism GWAS signals, indicating a non-genetic etiology for this process. Collectively, our results provide strong evidence for convergent molecular abnormalities in ASD, and implicate transcriptional and splicing dysregulation as underlying mechanisms of neuronal dysfunction in this disorder. Total RNA was extracted from approximately 100mg of postmortem brain tissue representing Cerebellum (C), Frontal cortex (F), and Temporal cortex (T), from autistic and control individuals.
Project description:Autism spectrum disorder (ASD) is a common, highly heritable neurodevelopmental condition characterized by marked genetic heterogeneity. Thus, a fundamental question is whether autism represents an aetiologically heterogeneous disorder in which the myriad genetic or environmental risk factors perturb common underlying molecular pathways in the brain. Here, we demonstrate consistent differences in transcriptome organization between autistic and normal brain by gene co-expression network analysis. Remarkably, regional patterns of gene expression that typically distinguish frontal and temporal cortex are significantly attenuated in the ASD brain, suggesting abnormalities in cortical patterning. We further identify discrete modules of co-expressed genes associated with autism: a neuronal module enriched for known autism susceptibility genes, including the neuronal specific splicing factor A2BP1 (also known as FOX1), and a module enriched for immune genes and glial markers. Using high-throughput RNA sequencing we demonstrate dysregulated splicing of A2BP1-dependent alternative exons in the ASD brain. Moreover, using a published autism genome-wide association study (GWAS) data set, we show that the neuronal module is enriched for genetically associated variants, providing independent support for the causal involvement of these genes in autism. In contrast, the immune-glial module showed no enrichment for autism GWAS signals, indicating a non-genetic aetiology for this process. Collectively, our results provide strong evidence for convergent molecular abnormalities in ASD, and implicate transcriptional and splicing dysregulation as underlying mechanisms of neuronal dysfunction in this disorder. To identify potential A2BP1-dependent differential splicing events in ASD brain, we performed high-throughput RNA sequencing (RNA-Seq) on three autism samples with significant downregulation of A2BP1 (average fold change by quantitative RT-PCR = 5.9) and three control samples with average A2BP1 levels. The list of potential A2BP1-depending differential splicing events in ASD is given in the Supplementary file linked at the foot of this record.
Project description:Individualized outcome prediction classifiers were successfully constructed through expression profiling of 91 up-regulated and 67 down-regulated miRNAs in 5 autism spectrum disorder (ASD) cases and 5 controls. In the study presented here, a well-defined cohort of 5 autism spectrum disorder cases and 5 controls was used to acquire expression profiles of 91 up-regulated and 67 down-regulated miRNAs, leading to the first global miRNA expression profile of ASD in China.