Systematic functional characterization of the intellectual disability-associated SWI/SNF complex reveals distinct roles for the BAP and PBAP complexes in post-mitotic memory forming neurons of the Drosophila mushroom body

Technology has led to rapid progress in the identification of genes involved in neurodevelopmental disorders like intellectual disability (ID), but our functional understanding of the causative genes is lagging. Here, we show that the SWI/SNF chromatin remodeling complex is one of the most overrepresented cellular components disrupted in ID. We systematically investigated the role of individual subunits of this large protein complex in post-mitotic memory forming neurons of the Drosophila mushroom body (MB). Using this approach, we have identified novel differential roles for the two prominent conformations of the Drosophila SWI/SNF complex, known as BAP and PBAP. The PBAP conformation is required post-mitotically for remodeling of the MBγ neurons during morphogenesis and is essential for both short and long-term memory. In contrast, the BAP conformation appears to preferentially effect long-term memory and is associated with MBγ neuron survival. Our results suggest that different subunits of the SWI/SNF complex may influence learning and memory through diverse and distinct roles in regulating structural plasticity, survival, and functionality of post-mitotic neurons. This study provides novel insight into the neuronal function of individual SWI/SNF subunits and will serve as a basis for understanding SWI/SNF-mediated gene regulatory mechanisms in post-mitotic neurons.