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AMPA receptors are exocytosed in stimulated spines and adjacent dendrites in a Ras-ERK-dependent manner during long-term potentiation

Patterson, Michael A., Szatmari, Erzsebet M., Yasuda, Ryohei
Proceedings of the National Academy of Sciences of the United States of America 2010 v.107 no.36 pp. 15951-15956
calcium-calmodulin-dependent protein kinase, dendrites, exocytosis, fluorescence, image analysis, receptors, signal transduction
The exocytosis of AMPA receptors is a key step in long-term potentiation (LTP), yet the timing and location of exocytosis and the signaling pathways involved in exocytosis during synaptic plasticity are not fully understood. Here we combine two-photon uncaging with two-photon imaging of a fluorescent label of surface AMPA receptors to monitor individual AMPA receptor exocytosis events near spines undergoing LTP. AMPA receptors that reached the stimulated spine came from a combination of preexisting surface receptors (70-90%) and newly exocytosed receptors (10-30%). We observed exocytosis in both the dendrite and spine under basal conditions. The rate of AMPA receptor exocytosis increased ~5-fold during LTP induction and decayed to the basal level within ~1 min, both in the stimulated spine and in the dendrite within ~3 μm of the stimulated spine. AMPA receptors inserted in the spine were trapped in the spine in an activity-dependent manner. The activity-dependent exocytosis required the Ras-ERK pathway, but not CaMKII. Thus, diffusive Ras-ERK signaling presumably serves as an important means for signaling from synapses to dendritic shafts to recruit AMPA receptors into synapses during LTP.