A presynaptic role for FMRP during protein synthesis-dependent long-term plasticity in Aplysia.

By selectively down-regulating Fragile X mental retardation protein (FMRP) in individual Aplysia neurons at the sensory-to-motor neuron synapse reconstituted in co-cultures, we demonstrate that FMRP functions both pre- and postsynaptically to constrain the expression of long-term synaptic depression induced by repeated pulses of FMRF-amide. Our findings suggest that FMRP can participate in the regulation of enduring synaptic plasticity that underlies the storage of certain types of long-term memory.