Hippocampal synaptic and circuit mechanisms mediating Dyrk1a functions in social cognition

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Project Summary/Abstract Autism spectrum disorder (ASD) is a class of heterogeneous neurodevelopmental disorders that affects 1 in 54 children in the United States and is characterized by impaired social cognition, repetitive behaviors and seizure risk. Genetic studies and large-scale exome-sequencing efforts have identified haplo-insufficient loss of function (LOF) mutations in the Dual specificity tyrosine-phosphorylation-regulated kinase Dyrk1a gene in syndromic ASD. However, the functional impact of hemizygous Dyrk1a LOF on synaptic and circuit mechanisms underlying social cognition remain poorly understood. This challenge is magnified because Dyrk1a phosphorylates >70 substrates and Dyrk1a LOF is likely to disrupt many biological processes during development. Currently, there are no drugs that enhance or restore Dyrk1a function. Together, these observations underscore the need to identify cell-type and circuit-specific mechanisms that maybe targeted to reverse Dyrk1a associated social cognition impairments. This proposal seeks to bridge these gaps by identifying a Dyrk1a-dependent synaptic and circuit mechanism mediating social recognition that can be targeted in adulthood to reverse developmental loss of Dyrk1a-associated impairments in social cognition circuitry and behavior. The proposed Aims will build on our in vivo functional genetic epistasis analysis of Dyrk1a and one of its substrates, Ablim3, in hippocampal mossy fibers to test the role of this pathway in reversing circuit and social recognition memory impairments in adult Dyrk1a hemizygous mice that models Dyrk1a haploinsufficiency in ASD. Execution of the Aims harbors potential to guide gene therapy strategies targeting molecular and circuit substrates of Dyrk1a, Ablim3 and parvalbumin inhibitory neuron mediated GABAergic inhibition, in the adult brain as “Dyrk1a enhancers” to rescue social cognition impairments in ASD resulting from Dyrk1a haploinsufficiency.