Neuronal transport granules: Single occupancy vehicles

The study recently was published in Proceedings of the National Academy of Sciences.

Proteins involved in transmissions at the axon tips and synapses of neurons travel there in precursor form (known as messenger RNA, or mRNA) as cargo of a structure known as a transport granule. "The idea is that the mRNAs located at the synapse will be translated [into protein] on demand," explains Tyagi, an associate professor in the Department of Medicine at UMDNJ-New Jersey Medical School and at the school's Public Health Research Institute. "And if more than one copy of a protein is required on site," Tyagi adds, "it can be produced from a single mRNA."

Some investigators have suggested that these mRNAs carpool with others in the same granule. But the study by Tyagi and colleagues shows that these mRNAs proceed single file, with only one mRNA per granule. Although it may seem more efficient to transport multiple mRNAs in a single trip, this may not allow the neuron the flexibility it needs for the proper formation and functioning of synapses.

An increased understanding of how these mRNAs are transported to synapses may help scientists unravel the longstanding mystery behind memory generation, which requires the formation of new synapses and the modification of old ones.