Cargo crowding at actin-rich regions along axons causes local traffic jams

Traffic. 2018 Mar;19(3):166-181. doi: 10.1111/tra.12544. Epub 2018 Feb 12.


Steady axonal cargo flow is central to the functioning of healthy neurons. However, a substantial fraction of cargo in axons remains stationary up to several minutes. We examine the transport of precursors of synaptic vesicles (pre-SVs), endosomes and mitochondria in Caenorhabditis elegans touch receptor neurons, showing that stationary cargo are predominantly present at actin-rich regions along the neuronal process. Stationary vesicles at actin-rich regions increase the propensity of moving vesicles to stall at the same location, resulting in traffic jams arising from physical crowding. Such local traffic jams at actin-rich regions are likely to be a general feature of axonal transport since they also occur in Drosophila neurons. Repeated touch stimulation of C. elegans reduces the density of stationary pre-SVs, indicating that these traffic jams can act as both sources and sinks of vesicles. This suggests that vesicles trapped in actin-rich regions are functional reservoirs that may contribute to maintaining robust cargo flow in the neuron. A video abstract of this article can be found at: Video S1; Video S2.

Keywords: Caenorhabditis elegans; Drosophila melanogaster; actin; axonal transport; neuronal stimulation; physical crowding; precursors of synaptic vesicles; reservoirs; stationary cargo; stationary vesicles; touch receptor neurons; traffic jams.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / metabolism
  • Animals
  • Axonal Transport*
  • Caenorhabditis elegans
  • Drosophila
  • Endosomes / metabolism
  • Mitochondria / metabolism
  • Synaptic Vesicles / metabolism


  • Actins