SYNAPTIC ACTIVATION CAUSES THE MESSENGER-RNA FOR THE IEG ARC TO LOCALIZE SELECTIVELY NEAR ACTIVATED POSTSYNAPTIC SITES ON DENDRITES

Polyribosomal complexes beneath postsynaptic sites on dendrites provid e a substrate for local translation of particular mRNAs, but the signa ls that target mRNAs to synapses remain to be defined. Here, we report that high frequency activation of the perforant path projections to t he dentate gyrus causes newly synthesized mRNA for the immediate-early gene (IEG) Are to localize selectively in activated dendritic segment s. Newly synthesized Are protein also accumulates in the portion of th e dendrite that had been synaptically activated. The targeting of Are mRNA was not disrupted by locally inhibiting protein synthesis, indica ting that the signals for mRNA localization reside in the mRNA itself. This novel mechanism through which newly synthesized mRNA is precisel y targeted to activated synapses is well suited to play a role in the enduring forms of activity-dependent synaptic modification that requir e protein synthesis.