Activity-dependent expression of brain-derived neurotrophic factor in dendrites: facts and open questions.

Long-lasting synaptic changes in transmission and morphology at the basis of memory storage, require delivery of newly synthesized proteins to affected synapses. Although many of these proteins are generated in the cell body, several key molecules for plasticity can be delivered in the form of silent mRNAs at synapses in extra somatic compartments where they are locally translated. One of such mRNAs encodes brain-derived neurotrophic factor (BDNF), a key molecule in neuronal development, learning and memory. A single BDNF protein is produced from several splice variants having a different 5' untranslated region. These mRNA variants have a different subcellular localization (soma, proximal or distal dendritic compartment) and may represent a spatial code for a local control of BDNF availability. This review will highlight current knowledge on the mechanisms of spatial and temporal regulation of activity-dependent BDNF mRNA localization in dendrites in relation with synaptic plasticity.