Rab27a co-ordinates actin-dependent transport by controlling organelle-associated motors and track assembly proteins

Nat Commun. 2020 Jul 13;11(1):3495. doi: 10.1038/s41467-020-17212-6.


Cell biologists generally consider that microtubules and actin play complementary roles in long- and short-distance transport in animal cells. On the contrary, using melanosomes of melanocytes as a model, we recently discovered that the motor protein myosin-Va works with dynamic actin tracks to drive long-range organelle dispersion in opposition to microtubules. This suggests that in animals, as in yeast and plants, myosin/actin can drive long-range transport. Here, we show that the SPIRE-type actin nucleators (predominantly SPIRE1) are Rab27a effectors that co-operate with formin-1 to generate actin tracks required for myosin-Va-dependent transport in melanocytes. Thus, in addition to melanophilin/myosin-Va, Rab27a can recruit SPIREs to melanosomes, thereby integrating motor and track assembly activity at the organelle membrane. Based on this, we suggest a model in which organelles and force generators (motors and track assemblers) are linked, forming an organelle-based, cell-wide network that allows their collective activity to rapidly disperse the population of organelles long-distance throughout the cytoplasm.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / metabolism*
  • Cell Biology
  • Cytoskeleton / metabolism
  • HEK293 Cells
  • Humans
  • Microtubules / metabolism
  • Organelles
  • Phylogeny
  • rab27 GTP-Binding Proteins / genetics
  • rab27 GTP-Binding Proteins / metabolism*


  • Actins
  • rab27 GTP-Binding Proteins
  • RAB27A protein, human