Mobility and cycling of synaptic protein-containing vesicles in axonal growth cone filopodia.
The spatial distribution and coordination of vesicular dynamics within growth cones are poorly understood. It has long been thought that membranous organelles are concentrated in the central regions of growth cones and excluded from filopodia; this view has dramatically shaped conceptual models of the cellular mechanisms of axonal growth and presynaptic terminal formation. To begin to test these models, we studied membrane dynamics within axonal growth cones of living rat cortical neurons. We demonstrate that growth cone filopodia contain vesicles that transport synaptic vesicle proteins bidirectionally along filopodia and fuse with the filopodial surface in response to focal stimulation, allowing for both local secretion of vesicular contents and rapid changes in the plasma membrane composition of individual filopodia. Our results suggest a new model in which growth cone filopodia are actively involved in both emitting and responding to local signals related to axon growth and early synapse formation.
Sabo
Shasta L
SL
Center for Neuroscience, University of California, Davis, 1544 Newton Court, Davis, California 95616, USA.
McAllister
A Kimberley
AK
D000818:Animals; D001369:Axons / Q000378:metabolism / Q000502:physiology*; D002465:Cell Movement / Q000502:physiology*; D002478:Cells, Cultured; D020439:Growth Cones / Q000378:metabolism / Q000502:physiology*; D008565:Membrane Proteins / Q000378:metabolism*; D017729:Presynaptic Terminals / Q000502:physiology*; D011554:Pseudopodia / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D013572:Synaptic Vesicles / Q000378:metabolism / Q000502:physiology
D008565:Membrane Proteins