Role of neuron-specific nucleosome remodeling in intellectual disability

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DESCRIPTION (provided by applicant): Intellectual disorders are characterized by impairments in cognition, social behaviors, and communication. Recent human exome sequencing studies have identified subunits of the polymorphic BAF complexes (mammalian SWI/SNF chromatin remodeling complex) that are frequently mutated in sporadic mental retardation and sporadic autism. Moreover, de novo mutations in various subunits of neuron-specific Brg1-associated factor (nBAF) nucleosome remodeling complex have been implicated in Coffin-Siris and Nicolaides-Baraitser syndromes, both of which are associated with intellectual disability. Together, these studies suggest that nBAF function is necessary for normal cognitive function. Nucleosome remodeling complexes modify chromatin structure and regulate expression by repositioning nucleosomes at the promoters of genes. Why disturbances to chromatin remodeling via mutations in BAF complexes result in cognitive dysfunction is unknown. Although an important topic in other fields (e.g. yeast genetics and cancer), nucleosome remodeling has received little attention in neuroscience. However, a major discovery was the identification of the first neuron-specific BAF complex, which was subsequently found to regulate gene expression required for the conversion of precursor cells into terminally differentiated neurons. Importantly, the nBAF complex has a subunit, BAF53b, which participates in making nBAF neuron- specific. This subunit is both neuron and nBAF complex specific, making it an ideal target for investigating the potential contributions of nBAF t synaptic physiology and behavior. Building on this point, we propose to test the hypothesis that BAF53b, after playing a key role in neuronal fate decisions during development, continues to regulate gene expression and does so in a manner critical to adult plasticity and memory. We propose three specific aims to test this hypothesis. In Aim 1, we will use genetically modified mice to examine the role of BAF53b in long-term memory. In Aim 2, we will examine the role of BAF53b in long-term potentiation, a form of synaptic plasticity. In Aim 3, we will use next generation sequencing, RNA seq, to determine what gene expression profiles are being regulated by BAF53b during memory consolidation. Together, the work under these aims will elucidate the contributions of BAF53b, and the nBAF complex in general, to memory processes, and thereby significantly contribute to the understanding of how mutations in the complex lead to cognitive impairments in humans.