Ca2+ induces macropinocytosis via F-actin depolymerization during growth cone collapse.
Growth cone collapse occurs in repulsive axon guidance and is accompanied by a reduction in the surface area of the plasma membrane of growth cones. However, the mechanism of this reduction is unclear. Here, we show that during growth cone collapse, caffeine-induced Ca(2+) release from ryanodine-sensitive Ca(2+) stores triggers the formation of large vacuoles in growth cones by macropinocytosis, a clathrin-independent endocytosis for the massive retrieval of the cellular plasma membrane, and subsequent retrograde membrane transport. We observed a significant correlation of the area of caffeine-induced macropinosomes with growth cone collapse. We also detected macropinocytosis induced by semaphorin 3A, a typical repulsive cue, and correlation between the area of semaphorin 3A-induced macropinocytic vacuoles and growth cone collapse. Moreover, jasplakinolide, an inhibitor of F-actin depolymerization, blocked caffeine-induced macropinocytosis. We propose that the coordinated regulation of actin cytoskeletal reorganization and macropinocytosis-mediated retrograde membrane trafficking may contribute to Ca(2+)-induced axon growth inhibition.
Laboratory for Developmental Neurobiology, Brain Science Institute, The Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan. kabayama@brain.riken.jp
Hiroyuki
H
Kabayama
Takeshi
T
Nakamura
Makoto
M
Takeuchi
Hirohide
H
Iwasaki
Masahiko
M
Taniguchi
Naoko
N
Tokushige
Katsuhiko
K
Mikoshiba
D000199:Actins / Q000378:metabolism*; D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D000697:Central Nervous System Stimulants / Q000494:pharmacology; D002614:Chelating Agents / Q000378:metabolism; D002642:Chick Embryo; D003911:Dextrans / Q000737:chemistry / Q000378:metabolism; D004533:Egtazic Acid / Q000378:metabolism; D005727:Ganglia, Spinal / Q000166:cytology; D020439:Growth Cones / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D009474:Neurons / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D010873:Pinocytosis / Q000502:physiology*; D012433:Ryanodine / Q000494:pharmacology; D040121:Semaphorin-3A / Q000378:metabolism; D012710:Serum Albumin, Bovine / Q000378:metabolism; D013223:Statistics as Topic; D014617:Vacuoles / Q000378:metabolism
D000199:Actins; D000697:Central Nervous System Stimulants; D002614:Chelating Agents; D003911:Dextrans; D040121:Semaphorin-3A; D012433:Ryanodine; D012710:Serum Albumin, Bovine; D002110:Caffeine; D004533:Egtazic Acid; D002118:Calcium