Functionally diverse dendritic mRNAs rapidly associate with ribosomes following a novel experience.

The subcellular localization and translation of messenger RNA (mRNA) supports functional differentiation between cellular compartments. In neuronal dendrites, local translation of mRNA provides a rapid and specific mechanism for synaptic plasticity and memory formation, and might be involved in the pathophysiology of certain brain disorders. Despite the importance of dendritic mRNA translation, little is known about which mRNAs can be translated in dendrites in vivo and when their translation occurs. Here we collect ribosome-bound mRNA from the dendrites of CA1 pyramidal neurons in the adult mouse hippocampus. We find that dendritic mRNA rapidly associates with ribosomes following a novel experience consisting of a contextual fear conditioning trial. High throughput RNA sequencing followed by machine learning classification reveals an unexpected breadth of ribosome-bound dendritic mRNAs, including mRNAs expected to be entirely somatic. Our findings are in agreement with a mechanism of synaptic plasticity that engages the acute local translation of functionally diverse dendritic mRNAs.