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:We used a microarray to compare bulk gene expression differences between ASD+/+ and ASD+/- tumor stroma. We observed enrichment for neutrophil transcripts in ASD+/- stroma compared to ASD+/+
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:Oligodendrocyte (OL) differentiation and myelin development are complex events regulated by numerous signal transduction factors. Here, we report that phosphoinositide-3 kinase enhancer L (PIKE-L) is required for OL development and myelination. PIKE-L expression is up-regulated when oligodendrocyte progenitor cells commit to differentiation. Conversely, depleting phosphoinositide-3 kinase enhancer (PIKE) expression by shRNA prevents oligodendrocyte progenitor cell differentiation. In both conventional PIKE knockout (PIKE(-/-)) and OL-specific PIKE knockout mice, the number of OLs is reduced in the corpus callosum. PIKE(-/-) OLs also display defects when forming myelin sheath on neuronal axons during neonatal development, which is partially rescued when PTEN is ablated. In addition, Akt/mTOR signaling is impaired in OL-enriched tissues of the PIKE(-/-) mutant, leading to reduced expression of critical proteins for myelin development and hypomyelination. Moreover, myelin repair of lysolecithin-induced lesions is delayed in PIKE(-/-) brain. Thus, PIKE plays pivotal roles to advance OL development and myelinogenesis through Akt/mTOR activation.
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.