Translational regulatory mechanisms in persistent forms of synaptic plasticity.

Memory and synaptic plasticity exhibit distinct temporal phases, with long-lasting forms distinguished by their dependence on macromolecular synthesis. Prevailing models for the molecular mechanisms underlying long-lasting synaptic plasticity have largely focused on transcriptional regulation. However, a growing body of evidence now supports a crucial role for neuronal activity-dependent mRNA translation, which may occur in dendrites for a subset of neuronal mRNAs. Recent work has begun to define the signaling mechanisms coupling synaptic activation to the protein synthesis machinery. The ERK and mTOR signaling pathways have been shown to regulate the activity of the general translational machinery, while the translation of particular classes of mRNAs is additionally controlled by gene-specific mechanisms. Rapid enhancement of the synthesis of a diverse array of neuronal proteins through such mechanisms provides the components necessary for persistent forms of LTP and LTD. These findings have important implications for the synapse specificity and associativity of protein synthesis-dependent changes in synaptic strength.