PUBLICATION

Synaptic activity and activity-dependent competition regulates axon arbor maturation, growth arrest, and territory in the retinotectal projection

Authors
Fredj, N.B., Hammond, S., Otsuna, H., Chien, C.B., Burrone, J., and Meyer, M.P.
ID
ZDB-PUB-100820-7
Date
2010
Source
The Journal of neuroscience : the official journal of the Society for Neuroscience   30(32): 10939-10951 (Journal)
Registered Authors
Chien, Chi-Bin, Otsuna, Hideo
Keywords
none
MeSH Terms
  • Tetanus Toxin/genetics
  • Embryo, Nonmammalian
  • Gene Expression Regulation, Developmental/drug effects
  • Gene Expression Regulation, Developmental/genetics
  • DNA-Binding Proteins/genetics
  • Pseudopodia/physiology
  • Axons/physiology*
  • Metalloendopeptidases/genetics
  • Synaptophysin/metabolism
  • Embryo, Mammalian
  • Superior Colliculi/cytology
  • Superior Colliculi/drug effects
  • Superior Colliculi/physiology*
  • Green Fluorescent Proteins/genetics
  • Cells, Cultured
  • Visual Pathways/drug effects
  • Visual Pathways/physiology
  • Zebrafish
  • Animals
  • Neurons/physiology*
  • Calcium/metabolism
  • Dizocilpine Maleate/pharmacology
  • Transfection/methods
  • Quaternary Ammonium Compounds
  • Analysis of Variance
  • Growth Cones/physiology
  • Zebrafish Proteins/genetics
  • Time Factors
  • Transcription Factors/genetics
  • Animals, Genetically Modified
  • Rats
  • Retina/cytology
  • Retina/drug effects
  • Retina/physiology*
  • Synapses/physiology*
  • Nystagmus, Optokinetic/drug effects
  • Nystagmus, Optokinetic/physiology
  • Rats, Sprague-Dawley
  • Excitatory Amino Acid Antagonists/pharmacology
  • Pyridinium Compounds
  • Hippocampus/cytology
PubMed
20702722 Full text @ J. Neurosci.
Abstract
In the retinotectal projection, synapses guide retinal ganglion cell (RGC) axon arbor growth by promoting branch formation and by selectively stabilizing branches. To ask whether presynaptic function is required for this dual role of synapses, we have suppressed presynaptic function in single RGCs using targeted expression of tetanus toxin light-chain fused to enhanced green fluorescent protein (TeNT-Lc:EGFP). Time-lapse imaging of singly silenced axons as they arborize in the tectum of zebrafish larvae shows that presynaptic function is not required for stabilizing branches or for generating an arbor of appropriate complexity. However, synaptic activity does regulate two distinct aspects of arbor development. First, single silenced axons fail to arrest formation of highly dynamic but short-lived filopodia that are a feature of immature axons. Second, single silenced axons fail to arrest growth of established branches and so occupy significantly larger territories in the tectum than active axons. However, if activity-suppressed axons had neighbors that were also silent, axonal arbors appeared normal in size. A similar reversal in phenotype was observed when single TeNT-Lc:EGFP axons are grown in the presence of the NMDA receptor antagonist MK801 [(+)-5-methyl-10,11- dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate]. Although expansion of arbor territory is prevented when neighbors are silent, formation of transient filopodia is not. These results suggest that synaptic activity by itself regulates filopodia formation regardless of activity in neighboring cells but that the ability to arrest growth and focusing of axonal arbors in the target is an activity-dependent, competitive process.
Genes / Markers
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Human Disease / Model
Sequence Targeting Reagents
Fish
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Engineered Foreign Genes
Mapping