It is becoming clear that autism spectrum disorder (ASD) likely occurs due to dysfunction of developing synapses andsynaptic remodeling. Tuberous sclerosis complex (TSC) is a monogenetic disease with a high incidence of ASD. Toobtain a deeper understanding of the underlying pathogenic mechanisms of ASD, we propose to take advantage of aTSC mouse model, which is missing the Tsc1 gene only in the cerebellar Purkinje cells (PCs). These conditionalTSC mutant mice exhibit the common core characteristics of ASD: lack of interest in socializing, repetitivebehaviors, and cognitive inflexibility. Importantly, Tsc1-deficient PCs display increased spine density, aphenotype previously reported in patients with neurodevelopmental disorders; however the neuronal and non-neuronal mechanisms that contribute this process remain elusive. In this project, we will investigate twocomplimentary mechanisms that contribute to the synaptic and behavioral phenotypes in this newly developedTSC mouse model of ASD. In Aim 1, we will test the hypothesis that impaired autophagy, driven by excessmTOR signaling, prevents normal synaptic remodeling and leads to the increased dendritic spine density onPCs, which contribute to the behavioral abnormalities found in the PC-Tsc1 CKO mice. We will characterizethe rate of autophagy including autophagy of mitochondria (mitophagy), and modulate autophagypharmacologically to test whether we can improve the spine and behavioral phenotypes. In Aim 2, we turn tocell-extrinsic mechanisms and ask whether the interaction between mutant PCs and microglia, residentimmune cells and key mediators of synaptic remodeling, contributes to the spine and ASD-like phenotypes. Wehypothesize that Tsc1-deficient Purkinje cells lead to early disruption in microglia development and function,including their ability to prune and signal to synapses. Moreover, our preliminary findings suggest that microgliaactivation and inflammatory signaling further contribute to synaptic and ASD like phenotypes. We are uniquely positioned to explore the spatio-temporal relationship of microglia changes relative toTsc1-null PCs using a combination of novel transcriptional profiling (single cell Drop-Seq), and functionalassays. We will perform the first detailed transcriptional analysis of microglia and neurons from TSC patientsand compare these data with mouse models. Finally, we will determine whether specific manipulation ofautophagy and microglia dysfunction in PC-TSC cKO mice rescue synaptic and specific ASD- relevantbehaviors. We will leverage four IDDRC cores (Cellular Imaging, Molecular Genetics, NeurodevelopmentalBehavior and Clinical Translational Cores) and complimentary expertise of co-PIs, Sahin and Stevens andIDDRC collaborators. Together, these experiments will shed light on the cell intrinsic and extrinsic mechanismsmediating synaptic modeling and may inform new therapeutic targets and biomarkers for TSC and relatedneurodevelopmental disorders.
Interagency Autism Coordinating Committee (IACC)
Autism Research Database (AFD)
