The prevalence and specificity of local protein synthesis during neuronal synaptic plasticity

To supply proteins to their vast volume, neurons localize mRNAs and ribosomes in dendrites and axons. While local protein synthesis is required for synaptic plasticity, the abundance and distribution of ribosomes and nascent proteins near synapses remain elusive. Here, we quantified the occurrence of local translation and visualized the range of synapses supplied by nascent proteins during basal and plastic conditions. We detected dendritic ribosomes and nascent proteins at single-molecule resolution using DNA-PAINT and metabolic labeling. Both ribosomes and nascent proteins positively correlated with synapse density. Ribosomes were detected at similar to 85% of synapses with similar to 2 translational sites per synapse; similar to 50% of the nascent protein was detected near synapses. The amount of locally synthesized protein detected at a synapse correlated with its spontaneous Ca2+ activity. A multifold increase in synaptic nascent protein was evident following both local and global plasticity at respective scales, albeit with substantial heterogeneity between neighboring synapses.

Automated summary

Neurons localize mRNAs and ribosomes in dendrites and axons for local protein synthesis to supply synapses. Study shows that ribosomes and nascent proteins positively correlate with synapse density and the amount of locally synthesized protein relates to spontaneous Ca2+ activity at synapses. Local and global plasticity result in a multifold increase in synaptic nascent protein with substantial heterogeneity between neighboring synapses.