Research Project
10350606
Project Summary/ Abstract The overall goal of this project is to identify the molecular determinants that act in the neuron and/or its target to promote the context-specific synaptic arbor elaboration and maintenance required for proper function. Once neurons find their synaptic partners, synaptic terminals must expand to an appropriate size to maintain synaptic fidelity. While the guidance cues that direct axons to their target area are well characterized, less is known about the molecular mechanisms that produce the stereotyped growth patterns unique to each synaptic terminal arbor. The clear link between dysfunction in circuit maintenance/synaptic transmission and neurological disease, such as autism and schizophrenia, underscores the urgency in delineating these molecular pathways. The strategy proposed to investigate this important developmental process is to examine how the Dpr and DIP subfamilies of Ig-domain cell-surface proteins (CSPs), instruct synaptic terminal elaboration and function. I will leverage the relative simplicity of the Drosophila neuromuscular circuit and the powerful genetic tools available to examine these questions with single-synapse resolution. My central hypothesis is that these CSPs initially determine target-specific synaptic arbor elaboration, and concurrently, organize synaptic active zones. To test this hypothesis, I will focus on DIP-? since my preliminary data suggests novel roles for DIP-? in both processes. In Aim 1, I will utilize cell-specific reporters to examine all motor neurons that express DIP-? to determine DIP-??s role is in instructing elaboration of specific synaptic terminal arbors. I will employ a candidate based genetic screen in order to uncover potential mechanisms. In Aim 2, I will characterize DIP-??s role in forming new and/or sculpting existing active zones through localization of a core active zone scaffolding protein. Additionally, I will perform simultaneous electrophysiological recordings and optogenetics to analyze motor neuron specific responses. From these studies, I anticipate unraveling new roles for DIPs in synapse specific elaboration and synaptogenesis. This proposal is innovative in that it combines interdisciplinary approaches, including electrophysiology, biochemistry, single-cell genetic manipulations, and microscopy, to elucidate fundamental mechanisms governing synaptic arbor expansion and neurotransmission. This research is significant because it addresses a long-held question in developmental neurobiology: how do discrete synaptic arbors of the same neuron acquire unique morphologies. Lastly, this project provides an ideal training opportunity to support my long-term professional goal of becoming an independent investigator focused on elucidating novel molecular mechanisms that underlie neural circuit development, and importantly, contributes to our understanding of how these molecular pathways can be disrupted to reveal disease etiologies.
