Imaging the motility of dendritic protrusions and axon terminals: roles in axon sampling and synaptic competition.
Dendritic spines and filopodia display actin-based morphological plasticity. The function of this rapid motility is unknown. Its ubiquitous expression during development has led to the hypothesis that motility plays a role in synaptogenesis. We investigated this by simultaneously imaging presynaptic boutons and dendritic protrusions in acute hippocampal slices from GFP-M transgenic mice loaded with FM 1-43 followed by immunostaining. Postsynaptic motility was inversely correlated with the presence of stable synaptic contacts. Filopodia were highly motile and made transient interactions, whereas spines were less motile and had stable contacts, although they could still move together with a synaptic terminal. "Head morphing" of spines was associated with interactions with more than one presynaptic terminal. Our data indicate that filopodia motility could serve to transiently sample the surrounding neuropil, while the motility of established spines could mediate interactions with two axonal terminals. Spine "morphing" could therefore be the morphological signature for synaptic input competition in central synapses.
Konur
Sila
S
Department of Biological Sciences, Columbia University, New York, NY 10027, USA. sk841@columbia.edu
Yuste
Rafael
R
D000818:Animals; D002450:Cell Communication / Q000502:physiology; D002465:Cell Movement / Q000502:physiology*; D048430:Cell Shape / Q000502:physiology; D049229:Dendritic Spines / Q000502:physiology* / Q000648:ultrastructure; D004558:Electric Stimulation; D049452:Green Fluorescent Proteins; D006624:Hippocampus / Q000502:physiology* / Q000648:ultrastructure; D019044:Image Cytometry; D007150:Immunohistochemistry; D008564:Membrane Potentials / Q000502:physiology; D051379:Mice; D008822:Mice, Transgenic; D018613:Microscopy, Confocal; D009473:Neuronal Plasticity / Q000502:physiology; D009924:Organ Culture Techniques; D017729:Presynaptic Terminals / Q000502:physiology* / Q000648:ultrastructure; D011554:Pseudopodia / Q000502:physiology* / Q000648:ultrastructure; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds; D013570:Synaptic Membranes / Q000378:metabolism / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000502:physiology
C073804:FM1 43; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds; D049452:Green Fluorescent Proteins