Regulation of AMPA Receptor–Mediated Synaptic Transmission by Clathrin-Dependent Receptor Internalization

AbstractRedistribution of postsynaptic AMPA- (α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid–) subtype glutamate receptors may regulate synaptic strength at glutamatergic synapses, but the mediation of the redistribution is poorly understood. We show that AMPA receptors underwent clathrin-dependent endocytosis, which was accelerated by insulin in a GluR2 subunit–dependent manner. Insulin-stimulated endocytosis rapidly decreased AMPA receptor numbers in the plasma membrane, resulting in long-term depression (LTD) of AMPA receptor–mediated synaptic transmission in hippocampal CA1 neurons. Moreover, insulin-induced LTD and low-frequency stimulation–(LFS-) induced homosynaptic CA1 LTD were found to be mutually occlusive and were both blocked by inhibiting postsynaptic clathrin-mediated endocytosis. Thus, controlling postsynaptic receptor numbers through endocytosis may be an important mechanism underlying synaptic plasticity in the mammalian CNS