Project description:Pathogenic heterozygous missense mutations in the DNM1 gene result in a novel form of epileptic encephalopathy. DNM1 encodes for the large GTPase dynamin-1, an enzyme with an obligatory role in the endocytosis of synaptic vesicles (SVs) at mammalian nerve terminals. Pathogenic DNM1 mutations cluster within regions required for its essential GTPase activity, implicating disruption of this enzyme activity as being central to epileptic encephalopathy. We reveal that the most prevalent pathogenic mutation in the GTPase domain of DNM1, R237W, disrupts dynamin-1 enzyme activity and SV endocytosis when overexpressed in central neurons. To determine how this dominant-negative heterozygous mutant impacted cell, circuit and behaviour when expressed from its endogenous locus, we generated a mouse carrying the R237W mutation. Neurons isolated from heterozygous mice displayed dysfunctional SV endocytosis, which translated into altered excitatory neurotransmission and seizure-like phenotypes. Importantly, these phenotypes were corrected at the cell, circuit and in vivo level by the drug, BMS-204352, which accelerates SV endocytosis in wild-type neurons. This study therefore provides the first direct link between dysfunctional SV endocytosis and epilepsy, and importantly reveals that SV endocytosis is a viable therapeutic route for monogenic intractable epilepsies.
Project description:Aristaless-related homeobox (ARX) is an X-linked gene encoding a bi-functional morphogenetic transcription factor with a key role in neuronal migration and brain development. Mutations in ARX have been identified in patients with X-linked Lissencephaly with Abnormal Genitalia (XLAG) and Early-infantile epileptic encephalopathy (EIEE). The aim of this project was to perform a proteomic analysis in whole neonatal brains isolated from XLAG and EIEE mouse models, ArxKO/Y and Arx(GCG)7/Y, to compare the mutant proteome profiles versus the wild-type ones by LC-MS/MS. By comparing the two proteomics profiles, common and different protein regulations emerged. Collectively, these findings could provide novel molecular insights into the proteomic mechanisms underlying XLAG and EIEE pathogenesis and may accelerate the design of pathway-guided therapeutic interventions for ARX-endophenotypes.
Project description:De novo mutations of the voltage-gated sodium channel SCN8A cause severe developmental and epileptic encephalopathy (DEE). Since pathogenic variants have gain-of-function effects on SCN8A activity, reduction of SCN8A expression is an effective therapeutic strategy. We previously described an antisense oligonucleotide (ASO) that delays seizure onset in a mouse model of SCN8A-DEE when administered at postnatal day 2. To investigate the potential effectiveness of post-onset ASO treatment, we first examined the extent of differential gene expression in hippocampus during the pre-onset period. Hippocampal single-nucleus RNA-sequencing detected only minor expression changes after the two month pre-seizure period. ASO treatments that were initiated after seizure onset were protective in the Scn8a mutant mice during the 12 month observation period. As an alternative treatment for down-regulation of Scn8a, we administered a single dose of an AAV10 virus expressing Scn8a shRNA. The viral shRNA was protective against seizures and lethality during the 12 month observation period. These data indicate that reduction of SCN8A expression, either by repeated administration of ASO or a single dose of shRNA virus, may be effective for longterm control of SCN8A-DEE.
Project description:De novo mutations of the voltage-gated sodium channel SCN8A cause severe developmental and epileptic encephalopathy (DEE). Since pathogenic variants have gain-of-function effects on SCN8A activity, reduction of SCN8A expression is an effective therapeutic strategy. We previously described an antisense oligonucleotide (ASO) that delays seizure onset in a mouse model of SCN8A-DEE when administered at postnatal day 2. To investigate the potential effectiveness of post-onset ASO treatment, we first examined the extent of differential gene expression in hippocampus during the pre-onset period. Hippocampal single-nucleus RNA-sequencing detected only minor expression changes after the two month pre-seizure period. ASO treatments that were initiated after seizure onset were protective in the Scn8a mutant mice during the 12 month observation period. As an alternative treatment for down-regulation of Scn8a, we administered a single dose of an AAV10 virus expressing Scn8a shRNA. The viral shRNA was protective against seizures and lethality during the 12 month observation period. These data indicate that reduction of SCN8A expression, either by repeated administration of ASO or a single dose of shRNA virus, may be effective for longterm control of SCN8A-DEE.
Project description:Scn1b null mice are a model of a severe developmental and epileptic encephalopathy called Dravet Syndrome (DS). The goal of this study was to identify changes in gene expression between Scn1b wild-type and Scn1b null mice before seizure onset (postnatal day 10)
Project description:We generated cerebral organoids from genetically engineered human embryonic stem cells (hESCs), modeling the devastating WOREE syndrome (DEE28), as a prototype for genetic epileptic encephalopathies (EEs). Transcriptome analysis of mutated organoids compared to the WT revealed molecular changes related to both early infantile EEs and specifically to WOREE syndrome.
Project description:Scn1b null mice are a model of a severe developmental and epileptic encephalopathy called Dravet Syndrome (DS). The goal of this study was to identify changes in gene expression between Scn1b wild-type and Scn1b null mice before seizure onset (postnatal day 10) in cortical layer VI, a region known to have differences in excitability in Scn1b null mice. RNA-Seq identified 21 genes, primarily extracellular matrix genes, which were differentially expressed between the two genotypes.
Project description:Epilepsy causes altered gene expression; transient adenosine treatment inhibits progression of epileptogenesis Hippocampus of epileptic rat is hypermethylated compared to naïve; adenosine treatment causes hypomethylation Metylation state in epileptic rats (9 weeks post kainic acid induced status epilepticus) was compared to naïve (untreated) rats and epileptic rats treated with adenosine for 5 days