It is becoming clear that autism spectrum disorder (ASD) likely occurs due to dysfunction of developing synapses and synaptic remodeling. Tuberous sclerosis complex (TSC) is a monogenetic disease with a high incidence of ASD. To obtain a deeper understanding of the underlying pathogenic mechanisms of ASD, we propose to take advantage of a TSC mouse model, which is missing the Tsc1 gene only in the cerebellar Purkinje cells (PCs). These conditional TSC mutant mice exhibit the common core characteristics of ASD: lack of interest in socializing, repetitive behaviors, and cognitive inflexibility. Importantly, Tsc1-deficient PCs display increased spine density, a phenotype 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 two complimentary mechanisms that contribute to the synaptic and behavioral phenotypes in this newly developed TSC mouse model of ASD.
In Aim 1, we will test the hypothesis that impaired autophagy, driven by excess mTOR signaling, prevents normal synaptic remodeling and leads to the increased dendritic spine density on PCs, which contribute to the behavioral abnormalities found in the PC-Tsc1 CKO mice. We will characterize the rate of autophagy including autophagy of mitochondria (mitophagy), and modulate autophagy pharmacologically to test whether we can improve the spine and behavioral phenotypes.
In Aim 2, we turn to cell-extrinsic mechanisms and ask whether the interaction between mutant PCs and microglia, resident immune cells and key mediators of synaptic remodeling, contributes to the spine and ASD-like phenotypes. We hypothesize 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 microglia activation 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 to Tsc1-null PCs using a combination of novel transcriptional profiling (single cell Drop-Seq), and functional assays. We will perform the first detailed transcriptional analysis of microglia and neurons from TSC patients and compare these data with mouse models. Finally, we will determine whether specific manipulation of autophagy and microglia dysfunction in PC-TSC cKO mice rescue synaptic and specific ASD- relevant behaviors. We will leverage four IDDRC cores (Cellular Imaging, Molecular Genetics, Neurodevelopmental Behavior and Clinical Translational Cores) and complimentary expertise of co-PIs, Sahin and Stevens and IDDRC collaborators. Together, these experiments will shed light on the cell intrinsic and extrinsic mechanisms mediating synaptic modeling and may inform new therapeutic targets and biomarkers for TSC and related neurodevelopmental disorders.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Specialized Center--Cooperative Agreements (U54)
Project #
5U54HD090255-04
Application #
9748886
Study Section
Special Emphasis Panel (ZHD1)
Project Start
Project End
Budget Start
2019-06-01
Budget End
2020-05-31
Support Year
4
Fiscal Year
2019
Total Cost
Indirect Cost
Name
Boston Children's Hospital
Department
Type
DUNS #
076593722
City
Boston
State
MA
Country
United States
Zip Code
02115
Schwartz, Talia S; Wojcik, Monica H; Pelletier, Renee C et al. (2018) Expanding the phenotypic spectrum associated with OPHN1 variants. Eur J Med Genet :
Marsh, Ashley P L; Edwards, Timothy J; Galea, Charles et al. (2018) DCC mutation update: Congenital mirror movements, isolated agenesis of the corpus callosum, and developmental split brain syndrome. Hum Mutat 39:23-39
Sveinsdóttir, Kristbjörg; Ley, David; Hövel, Holger et al. (2018) Relation of Retinopathy of Prematurity to Brain Volumes at Term Equivalent Age and Developmental Outcome at 2 Years of Corrected Age in Very Preterm Infants. Neonatology 114:46-52
Sieberg, Christine B; Taras, Caitlin; Gomaa, Aya et al. (2018) Neuropathic pain drives anxiety behavior in mice, results consistent with anxiety levels in diabetic neuropathy patients. Pain Rep 3:e651
Sourati, Jamshid; Gholipour, Ali; Dy, Jennifer G et al. (2018) Active Deep Learning with Fisher Information for Patch-wise Semantic Segmentation. Deep Learn Med Image Anal Multimodal Learn Clin Decis Support ( 11045:83-91
Koczkowska, Magdalena; Chen, Yunjia; Callens, Tom et al. (2018) Genotype-Phenotype Correlation in NF1: Evidence for a More Severe Phenotype Associated with Missense Mutations Affecting NF1 Codons 844-848. Am J Hum Genet 102:69-87
Liang, Liang; Fratzl, Alex; Goldey, Glenn et al. (2018) A Fine-Scale Functional Logic to Convergence from Retina to Thalamus. Cell 173:1343-1355.e24
Torres, Alcy; Brownstein, Catherine A; Tembulkar, Sahil K et al. (2018) De novo ATP1A3 and compound heterozygous NLRP3 mutations in a child with autism spectrum disorder, episodic fatigue and somnolence, and muckle-wells syndrome. Mol Genet Metab Rep 16:23-29
Shannon, Morgan L; Fame, Ryann M; Chau, Kevin F et al. (2018) Mice Expressing Myc in Neural Precursors Develop Choroid Plexus and Ciliary Body Tumors. Am J Pathol 188:1334-1344
Waszak, Sebastian M; Northcott, Paul A; Buchhalter, Ivo et al. (2018) Spectrum and prevalence of genetic predisposition in medulloblastoma: a retrospective genetic study and prospective validation in a clinical trial cohort. Lancet Oncol 19:785-798

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