Abstract
The development and structural plasticity of dendritic arbors are governed by several factors, including synaptic activity, neurotrophins and other growth-regulating molecules. The signal transduction pathways leading to dendritic structural changes are unknown, but likely include cytoskeleton regulatory components. To test whether GTPases regulate dendritic arbor development, we collected time-lapse images of single optic tectal neurons in albino Xenopus tadpoles expressing dominant negative or constitutively active forms of Rac, Cdc42 or RhoA. Analysis of images collected at two-hour intervals over eight hours indicated that enhanced Rac activity selectively increased branch additions and retractions, as did Cdc42 to a lesser extent. Activation of endogenous RhoA decreased branch extension without affecting branch additions and retractions, whereas dominant-negative RhoA increased branch extension. Finally, we provide data suggesting that RhoA mediates the promotion of normal dendritic arbor development by NMDA receptor activation.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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2-Amino-5-phosphonovalerate / pharmacology
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Actins / metabolism
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Animals
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Cell Size / drug effects
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Cytoskeleton / drug effects
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Cytoskeleton / metabolism
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Dendrites / drug effects
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Dendrites / enzymology*
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Dendrites / physiology*
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Dendrites / ultrastructure
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Enzyme Activation / genetics
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Genes, Dominant / genetics
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Humans
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Larva / cytology
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Larva / drug effects
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Mutation / genetics
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Neuronal Plasticity / drug effects
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Receptors, N-Methyl-D-Aspartate / antagonists & inhibitors
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Receptors, N-Methyl-D-Aspartate / physiology
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Signal Transduction / drug effects
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Superior Colliculi / cytology*
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Superior Colliculi / drug effects
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Superior Colliculi / enzymology
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Superior Colliculi / metabolism
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Vaccinia virus / genetics
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Xenopus laevis
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cdc42 GTP-Binding Protein / genetics
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cdc42 GTP-Binding Protein / metabolism
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rac GTP-Binding Proteins / genetics
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rac GTP-Binding Proteins / metabolism
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rho GTP-Binding Proteins / genetics
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rho GTP-Binding Proteins / metabolism*
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rhoA GTP-Binding Protein / genetics
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rhoA GTP-Binding Protein / metabolism
Substances
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Actins
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Receptors, N-Methyl-D-Aspartate
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Recombinant Fusion Proteins
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2-Amino-5-phosphonovalerate
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cdc42 GTP-Binding Protein
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rac GTP-Binding Proteins
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rho GTP-Binding Proteins
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rhoA GTP-Binding Protein