Proper regulation of synaptic development and plasticity are fundamental to the function of neural circuits. Defects in synaptic growth are associated with a broad range of neurological disorders. However, the molecular mechanisms regulating synaptic growth are not well understood. Our research employs the Drosophila neuromuscular junction (NMJ) as a model system for dissecting the intrinsic and trans-synaptic mechanisms through which neurons and their targets coordinate the assembly and growth of synapses. We are currently focusing on:
1. Identification and characterization of novel regulators of synapse formation and function. The identification and characterization of novel regulators of synapse formation and function can expand our understanding of this intricate process in unexpected ways. To that end, we have conducted forward genetic screens for genes required for proper synapse development. We are now employing genetic, imaging, biochemical, electrophysiological and behavioral approaches to characterize the regulators we have identified.
One such gene is Fife, the Drosophila homolog of Piccolo, a core component of presynaptic active zones previously believed absent from invertebrate proteomes. We have found that Fife regulates synaptic architecture at active zones to control neurotransmitter release. We are currently working to understand the molecular mechanisms of Fife function and its role in synaptic plasticity.
2. Trans-synaptic regulation of growth factor signaling. It is well known that postsynaptic cells can regulate the size and strength of the synaptic inputs they receive through instructive signaling to presynaptic neurons. We have found that presynaptic neurons, rather than passive recipients of these cues, can control their level of responsiveness to signals from their postsynaptic partners through the endocytic regulation of growth factor receptors. We are studying the role of this mechanism in synapse development and plasticity in Drosophila and mammalian neurons.
3. Genome engineering. Genetic and molecular techniques to manipulate the genomes of organisms are invaluable tools for understanding gene function. In collaboration with the Wildonger and Harrison labs, we demonstrated that the bacterially derived CRISPR RNA-guided Cas9 nuclease can be employed to delete and replace genes in Drosophila, and that these genome modifications can be efficiently transmitted through the germline. We have since optimized tools and techniques for CRISPR-catalyzed homologous recombination and developed an online tool for identifying highly specific CRISPR target sites. We are currently focused on expanding and optimizing CRISPR/Cas9 genome engineering to overcome current technological barriers to understanding neural circuits. For more information visit the flyCRISPR website and discussion board.