Persistent changes in synaptic strength are locally regulated by both protein degradation and synthesis; however, the coordination of these opposing limbs is poorly understood. Here, we found that the RISC protein MOV10 was present at synapses and was rapidly degraded by the proteasome in an NMDA-receptor-mediated activity-dependent manner. We designed a translational trap to capture those mRNAs whose spatiotemporal translation is regulated by MOV10. When MOV10 was suppressed, a set of mRNAs—including α-CaMKII, Limk1, and the depalmitoylating enzyme lysophospholipase1 (Lypla1)—selectively entered the polysome compartment. We also observed that Lypla1 mRNA is associated with the brain-enriched microRNA miR-138. Using a photoconvertible translation reporter, Kaede, we analyzed the activity-dependent protein synthesis driven by Lypla1 and α-CaMKII 3′UTRs. We established this protein synthesis to be MOV10 and proteasome dependent. These results suggest a unifying picture of a local translational regulatory mechanism during synaptic plasticity.
