A novel action of collapsin: collapsin-1 increases antero- and retrograde axoplasmic transport independently of growth cone collapse.
Chick collapsin-1, a member of the semaphorin family, has been implicated in axonal pathfinding as a repulsive guidance cue. Collapsin-1 induces growth cone collapse via a pathway which may include CRMP-62 and heterotrimeric G proteins. CRMP-62 protein is related to UNC-33, a nematode neuronal protein required for appropriately directed axonal extension. Mutations in unc-33 affect neural microtubules, the basic cytoskeletal elements for axoplasmic transport. Using computer-assisted video-enhanced differential interference contrast microscopy, we now demonstrate that collapsin-1 potently promotes axoplasmic transport. Collapsin-1 doubles the number of antero- and retrograde-transported organelles but not their velocity. Collapsin-1 decreases the number of stationary organelles, suggesting that the fraction of time during which a particle is moving is increased. Collapsin-1-stimulated transport occurs by a mechanism distinct from that causing growth cone collapse. Pertussis toxin (PTX) but not its B oligomer blocks collapsin-induced growth cone collapse. The holotoxin does not affect collapsin-stimulated axoplasmic transport. Mastoparan and a myelin protein NI-35 induce PTX-sensitive growth cone collapse but do not stimulate axoplasmic transport. These results provide evidence that collapsin has a unique property to activate axonal vesicular transport systems. There are at least two distinct pathways through which collapsin exerts its actions in developing neurons.
Goshima
Y
Y
Department of Pharmacology, Yokohama City University School of Medicine, Yokohama, Japan.
Kawakami
T
T
Hori
H
H
Sugiyama
Y
Y
Takasawa
S
S
Hashimoto
Y
Y
Kagoshima-Maezono
M
M
Takenaka
T
T
Misu
Y
Y
Strittmatter
S M
SM
D000818:Animals; D001370:Axonal Transport / Q000187:drug effects*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D019204:GTP-Binding Proteins / Q000378:metabolism; D005727:Ganglia, Spinal / Q000166:cytology; D006023:Glycoproteins / Q000494:pharmacology*; D036341:Intercellular Signaling Peptides and Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D009185:Myelin Proteins / Q000494:pharmacology; D009414:Nerve Growth Factors / Q000494:pharmacology; D016501:Neurites / Q000187:drug effects / Q000502:physiology*; D015388:Organelles / Q000378:metabolism; D010455:Peptides; D037342:Pertussis Toxin; D040121:Semaphorin-3A; D010566:Virulence Factors, Bordetella / Q000494:pharmacology; D014862:Wasp Venoms / Q000494:pharmacology
D006023:Glycoproteins; D036341:Intercellular Signaling Peptides and Proteins; D009185:Myelin Proteins; D009414:Nerve Growth Factors; D010455:Peptides; D040121:Semaphorin-3A; D010566:Virulence Factors, Bordetella; D014862:Wasp Venoms; C037500:mastoparan; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins