Project description:Autism spectrum disorder (ASD) is characterized by a complex etiology, with genetic determinants significantly influencing its manifestation. Among these, the Scn2a gene emerges as a pivotal player, crucially involved in oligodendrocyte (OL) function. The present study elucidates the underexplored roles of Scn2a in OL functionality, subsequently affecting myelination and auditory neural processes. The results reveal a nuanced interplay between OLs and axons, where Scn2a deletion causes alterations in OL differentiation and myelination. This disruption, in turn, instigates changes in axonal properties and neuronal activities at the single cell level. Furthermore, OL-specific Scn2a deletion compromises the integrity of neural circuitry within auditory pathways, leading to auditory hypersensitivity—a common sensory abnormality observed in ASD. Through transcriptional profiling, we identified alterations in the expression of myelin-associated genes, highlighting the cellular consequences engendered by Scn2a deletion. In summary, the findings of this study provide unprecedented insights into the pathway from Scn2a deletion in OL to sensory abnormalities in ASD, underscoring the integral role of Scn2a-mediated OL myelination in auditory responses. This research thereby provides novel insights into the intricate tapestry of genetic and cellular interactions inherent in ASD.
Project description:Myelinating glia in the auditory system enclose auditory nerve fibers, providing an insulating effect that facilitates rapid transfer of auditory information from the ear to the brain. Here we show that noise exposure at the levels sufficient for inducing hearing loss cause a rapid cellular and molecular response on myelinating glia that precedes neuron degeneration. The response is characterized by inflammatory response, myelin dysmorphology and widespread changes in myelin-related gene expression. Another characteristic was change in expression of the quaking gene (QKI), which encodes a group of RNA binding proteins that are enriched in myelinating glia. Changes in QKI were accompanied by changes in numerous known and potential QKI target genes, including many genes associated with myelination. Our results implicate QKI as a critical early component in the noise response, influencing glia dysfunction that leads to auditory nerve demyelination and, ultimately, sensorineural hearing loss.
Project description:Myelination depends on maintenance of oligodendrocytes that arise from oligodendrocyte precursor cells (OPCs). We show that OPC-specific proliferation, morphology, and BMAL1 are time-of-day dependent. Knock out of Bmal1 in OPCs during development disrupts expression of genes associated with circadian rhythms, proliferation, density, morphology, and migration, leading to changes in OPC dynamics in a spatio-temporal manner. Furthermore, these deficits translate into thinner myelin, dysregulated cognitive and motor function, and increased sleep fragmentation. OPC-specificBmal1loss in adulthood does not alter OPC density at baseline but impairs remyelination of a demyelinated lesion driven by changes in OPC morphology and migration. Lastly, we show sleep fragmentation is associated with increased prevalence of the demyelinating disorder multiple sclerosis (MS), suggesting a link between MS and sleep that requires further investigation. These findings have broad mechanistic and therapeutic implications for brain disorders that include both myelin and sleep phenotypes.
Project description:We characterized the proteome of the auditory brainstem of a chick embryo on embryonic day 13, when apoptosis occurs in auditory nuclei. We identified caspase substrates by searching the peptidome for peptides C-terminal to caspase-typical cleavage sites.
Project description:Sound localization requires extremely precise development of auditory brainstem circuits, the molecular mechanisms of which are largely unknown. We previously demonstrated a novel requirement for non-apoptotic activity of the protease caspase-3 in chick auditory brainstem development. Here, we used mass spectrometry to identify proteolytic substrates of caspase-3 during chick auditory brainstem development. Functional annotation analysis revealed that our caspase-3 substrates were enriched more than two-fold for proteins associated with extracellular vesicles (EVs), membrane-bound nanoparticles that function in intercellular communication. The proteome of EVs isolated from the auditory brainstem contained caspase-3 and was highly enriched for the caspase-3 substrates identified here. Additionally, we identified two caspase-3 substrates with known functions in axon guidance, namely Neural Cell Adhesion Molecule (NCAM) and Neuronal-glial Cell Adhesion Molecule (Ng-CAM), that were found in auditory brainstem EVs and expressed in the auditory pathway alongside cleaved caspase-3. Taken together, these data suggest a novel developmental mechanism whereby caspase-3 influences auditory brainstem circuit formation through the proteolytic cleavage of EV proteins.
Project description:We postulated that specific differences in alternative splicing/exon usage in immune blood cells may be present in ASD boys, and this might differ in ASD boys with large total cerebral volumes (ASD_LTCV) versus ASD boys with normal total cerebral volumes (ASD_NTCV). Thus, we compared ASD and ASD sub-groups related to total cerebral volume to typically developing (TD) controls.
Project description:Autism Spectrum disorder (ASD) is a heterogeneous neurodevelopmental disorder where patients have impaired social behavior and communication, and restricted interests. Although various studies have been carried out to unveil the mechanisms associated with ASD, its pathophysiology is still poorly understood. Genetic variants on CNTNAP2 have been found and considered representative ASD genetic risk factors, and disruption of Cntnap2 causes ASD phenotypes in mice. Here, we performed an integrative multi-omics analysis by combining quantitative proteometabolomics data of Cntnap2 knockout (KO) mice with multi-omics data from ASD patients and forebrain organoids to elucidate Cntnap2-dependent molecular networks of ASD. First, we found Cntnap2-associated molecular signatures and cellular processes by conducting mass spectrometry-based proteometabolomic analysis of the medial prefrontal cortex of the Cntnap2 KO mouse model. Then, we narrowed these identified processes into bona fide ASD molecular processes by incorporating multi-omics data of ASD patients' prefrontal cortex. Further, we mapped cell-type-specific ASD networks by reanalyzing single-cell RNA-seq data of forebrain organoids derived from patients with CNTNAP2 mutation. Finally, we constructed a Cntnap2-associated ASD network model consisting of mitochondrial dysfunction, axonal impairment, and synaptic activity. Our results may shed light on understanding of the Cntnap2-dependent molecular networks of ASD.