Revealing acute consequences of rapid degradation of synaptic fusion proteins at individual synapses using Auxin-Inducible Degron 2 technology

Roles of particular proteins in synaptic organization and function are commonly studied by knock-out, knock-down or overexpression strategies. Such approaches are typically protracted, associated with adaptive changes and challenge the ability to observe acute consequences at individual synapses. Here we describe the use of Auxin-Inducible Degron 2 (AID2) technology and coexpressed reporters to study real-time effects of rapidly degrading postsynaptic density proteins at individual synapses. We establish the capacity of AID2 technology to rapidly degrade postsynaptic scaffold fusion proteins in cultured neurons and in vivo. We show that acute PSD-95 or gephyrin degradation leads to concomitant loss of AMPA or GABA_A receptors from the same synapses. Unexpectedly, we find that acute GKAP, but not PSD-95 degradation, is associated with scaffold size reductions at the same synapses. Our findings demonstrate the utility of approaches based on acute degradation and live imaging for studying the roles of select proteins in synaptic organization.