Role of SNARE Interactions in Central Synapse Function

Project-Summary Recent studies have identified a large number of variants in SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) machinery components such as SNAP25 that give rise to intractable early childhood brain disorders. In this project, we will use rodent hippocampal neurons as well as human embryonic stem cell derived neurons and a unique SNAP25 variant knock-in mouse model, to fully define the synaptic transmission and plasticity deficits associated with key disease causing SNAP25 variants and evaluate their responsiveness to neurotherapeutics. Importantly, our studies have identified SNAP25 variants that dramatically alter spontaneous release with limited or no effect on properties of action potential evoked neurotransmission. As spontaneous release process is a key determinant of synapses' homeostatic state and responsiveness to certain neurotherapeutics, we expect that the effects of these mutations will go beyond their immediate impact on the release process and alter synaptic plasticity as well as treatment response. Overall, we aim to test the hypothesis that disease causing neurotransmitter release machinery variants elicit crucial downstream signaling defects altering plasticity mechanisms that affect responsiveness to therapeutics via three Specific Aims. The first aim will address synaptic mechanisms adversely affected by SNAP25 variants using electrophysiology, single synapse optical imaging, electron-microscopy and super-resolution imaging. The second aim will focus on examining SNAP25 variant induced synaptic deficits in human neurons. In this system, we will evaluate the impact of experimental therapeutics that elicit homeostatic synaptic plasticity on SNAP25 variant induced deficits. Finally, aim 3 will examine circuit specific synaptic transmission and plasticity deficits in a unique SNAP25 variant mouse model. Information attained from these studies will provide new insight to the synaptic substrates that are affected not only by these disorders but also a number of neuropsychiatric and neurological disorders with synaptic abnormalities including major depressive disorder, autism, schizophrenia and neurodegeneration.