Nanoscale cellular and molecular fingerprints of synaptic diversity

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Functional synaptic diversity is critical for routing and encoding sensory information in the brain. Yet, the molecular and biophysical underpinnings of such diversity remain unexplored. We hypothesize that nanoscale variations in the number and location of active zone scaffold proteins, as well as synapse-specific expression of the molecular machinery controlling their fusion, contribute to functional synaptic diversity. Using the mouse somatosensory cortex and cerebellum we will identify the molecular and biophysical mechanisms underlying the diversity of inhibitory and excitatory synapses (strong and weak), which are responsible for sensory perception. Many candidate molecules influencing synaptic behavior have been identified in the drosophila model system. Here we propose to use super-resolution imaging of synaptic molecules to identify their binding partners and characterize their nanoscale architecture (molecular fingerprint), which ultimately influences the distance between calcium channels and synaptic vesicles. In order to establish a structure function relationship, we will estimate coupling distances using combining optical and biophysical approaches at single boutons. Finally, causal experiments will be performed by genetic alteration (Crisper/Cas9 gene editing) of key active zone scaffold proteins to confirm their specific role in setting coupling distance. We expect to elucidate general molecular rules defining functional diversity throughout the brain. Because of the involvement of presynaptic proteins in several brain disorders and the molecular nature and cross-brain breadth of our study, this research will provide a foundation for therapeutic future interventions.