Project description:Shank3 is an abundant excitatory postsynaptic scaffolding proteins implicated in various neurodevelopmental and psychiatric disorders, including ASD, Phelan-McDermid syndrome, intellectual disability, and schizophrenia. Shank3-mutant mice with a homozygous deletion of exons 14-16 (Shank3-HM mice) show ASD-like behavioral deficits and altered synaptic and neuronal functions, but little is known about how different ages, brain regions, and gene dosages contribute to transcriptomic phenotypes in these mice. Here, we performed RNA-Seq-based transcriptomic analyses of the prefrontal cortex, hippocampus, and striatum in adult Shank3 heterozygous- and homozygous-mutant mice. In addition, juvenile and adult Shank3 homozygous-mutant forebrain transcriptomes were compared. Juvenile and adult forebrain transcriptomes from Shank3 homozygous-mutant mice showed the patterns that are opposite and similar to those observed in ASD: reverse-ASD and ASD-like patterns, respectively. Here, the juvenile reverse-ASD pattern involved synaptic gene upregulations and ribosomal and mitochondrial downregulations, whereas the adult ASD-like pattern involved opposite changes. Gene set enrichment analyses (GSEA) of brain regional transcripts in adult Shank3-HT and Shank3-HM mice revealed that the cortical, hippocampal, and striatal transcripts show distinctly altered biological functions and ASD-related/risk gene expressions. The cortex and striatum display ASD-like patterns whereas the hippocampus displays reverse-ASD patterns. The cortical ASD-like pattern more strongly involves ASD-risk genes whereas the striatal ASD-like pattern more strongly involves astrocyte/microglia genes. Shank3-HT and Shank3-HM transcripts in a given brain region display largely similar patterns in biological functions and ASD-related/risk gene expressions, suggestive of small gene dosage effects. These results suggest that heterozygous and homozygous Shank3 deletions in mice lead to age, brain region, and gene dosage-differential transcriptomic changes.

Project description:Austism spectrum disorder (ASD) is a heterogeneous behavioral disease most commonly characterized by severe impairment of social engagement and the presence of repetitive activities. The molecular etiology of ASD is still largely unknown despite a strong genetic component. Part of the difficulty in turning genetics into disease mechanisms and potentially new therapeutics is the sheer number and diversity of the genes that have been associated with ASD and ASD symptoms. The goal of this work is to use shRNA-generated models of genetic defects proposed as causative for ASD to identify the common pathways that might explain how they produce a common clinical outcome. Transcript levels of Mecp2, Mef2a, Mef2d, Fmr1, Nlgn1, Nlgn3, Pten, and Shank3 were knocked-down in mouse primary neuron cultures using shRNA/lentivirus constructs. Whole genome expression analysis was conducted for each of the knock-down cultures as well as a mock-transduced culture and a culture exposed to a lentivirus expressing luciferase. Gene set enrichment and a causal reasoning engine were employed to indentify pathway level perturbations generated by the transcript knock-down. Quantitation of the shRNA targets confirmed the successful knock-down at the transcript and protein levels of at least 75% for each of the genes. After subtracting out potential artifacts caused by transfection and viral infection, gene set enrichment and causal reasoning engine analysis showed that a significant number of gene expression changes mapped to pathways associated with neurogenesis, long-term potentiation, and synaptic activity. This work demonstrates that despite the complex genetic nature of ASD, there are common molecular mechanisms that connect many of the best established autism candidate genes. By identifying the key regulatory checkpoints in the interlinking transcriptional networks underlying autism, we are better able to discover the ideal points of intervention that provide the broadest efficacy across the diverse population of autism patients. n=4 per group. Luciferase shRNA used as control group for shRNA to various gene targets.

Project description:Austism spectrum disorder (ASD) is a heterogeneous behavioral disease most commonly characterized by severe impairment of social engagement and the presence of repetitive activities. The molecular etiology of ASD is still largely unknown despite a strong genetic component. Part of the difficulty in turning genetics into disease mechanisms and potentially new therapeutics is the sheer number and diversity of the genes that have been associated with ASD and ASD symptoms. The goal of this work is to use shRNA-generated models of genetic defects proposed as causative for ASD to identify the common pathways that might explain how they produce a common clinical outcome. Transcript levels of Mecp2, Mef2a, Mef2d, Fmr1, Nlgn1, Nlgn3, Pten, and Shank3 were knocked-down in mouse primary neuron cultures using shRNA/lentivirus constructs. Whole genome expression analysis was conducted for each of the knock-down cultures as well as a mock-transduced culture and a culture exposed to a lentivirus expressing luciferase. Gene set enrichment and a causal reasoning engine were employed to indentify pathway level perturbations generated by the transcript knock-down. Quantitation of the shRNA targets confirmed the successful knock-down at the transcript and protein levels of at least 75% for each of the genes. After subtracting out potential artifacts caused by transfection and viral infection, gene set enrichment and causal reasoning engine analysis showed that a significant number of gene expression changes mapped to pathways associated with neurogenesis, long-term potentiation, and synaptic activity. This work demonstrates that despite the complex genetic nature of ASD, there are common molecular mechanisms that connect many of the best established autism candidate genes. By identifying the key regulatory checkpoints in the interlinking transcriptional networks underlying autism, we are better able to discover the ideal points of intervention that provide the broadest efficacy across the diverse population of autism patients.

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Disrupted extracellular matrix and cell cycle genes in autism-associated Shank3 deficiency can be rescued with Lithium

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