Perplexing bodies

Processing bodies (P-bodies) have recently come to the fore as important cellular sites of mRNA degradation and translational silencing. Despite these central functions in the control of gene expression, the roles of P-bodies have only been characterized in a limited number of cell types and physiological contexts. Neurons are highly plastic cells that undergo dynamic changes as new connections are made or existing ones modified. This neuronal plasticity relies, in part, on the local synthesis of proteins from localized mRNAs. A strict control of the translation and turnover of these localized mRNAs, both in terms of which proteins are synthesized and when and where they are produced, is a key prerequisite for this process to be synapse-specific. Despite recent advances, the molecular mechanisms mediating this control remain largely elusive. The discovery of P-bodies in neuronal dendrites near synapses and their response to stimuli involved in neuronal plasticity raises the interesting hypothesis that P-bodies might be a component of the cellular machinery that controls neuronal plasticity and thereby processes such as learning and memory.