Abstract
Large clostridial cytotoxins and protein overexpression were used to probe for involvement of Ras-related GTPases (guanosine triphosphate) in synaptic transmission in cultured rat hippocampal neurons. The toxins TcdA-10463 (inactivates Rho, Rac, Cdc42, Rap) and TcsL-1522 (inactivates Ral, Rac, Ras, R-Ras, Rap) both inhibited autaptic responses. In a proportion of the neurons (25%, TcdA-10463; 54%, TcsL-1522), the inhibition was associated with a shift from activity-dependent depression to facilitation, indicating that the synaptic release probability was reduced. Overexpression of a dominant negative Ral mutant, Ral A28N, caused a strong inhibition of autaptic responses, which was associated with a shift to facilitation in a majority (80%) of the neurons. These results indicate that Ral, along with at least one other non-Rab GTPase, participates in presynaptic regulation in hippocampal neurons.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Alanine / genetics
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Animals
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Arabidopsis Proteins / pharmacology
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Asparagine / genetics
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Bacterial Toxins / pharmacology
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Blotting, Western / methods
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Carbon Isotopes / pharmacology
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Cells, Cultured
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Drug Interactions
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Electric Stimulation / methods
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Enterotoxins / pharmacology
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Excitatory Amino Acid Agonists / pharmacology
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Gene Expression Regulation / genetics
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Gene Expression Regulation / physiology
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Glucose / metabolism
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Hippocampus / cytology*
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Membrane Potentials / drug effects
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Membrane Potentials / physiology
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Membrane Potentials / radiation effects
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Mutation / physiology
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Neural Inhibition / drug effects
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Neural Inhibition / physiology*
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Neurons / drug effects
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Neurons / physiology*
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Patch-Clamp Techniques / methods
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Rats
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Synaptic Transmission / drug effects
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Synaptic Transmission / physiology*
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Toxins, Biological / pharmacology
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Transfection / methods
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alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / pharmacology
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gamma-Aminobutyric Acid / pharmacology
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ral GTP-Binding Proteins / physiology*
Substances
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Arabidopsis Proteins
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Bacterial Toxins
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Carbon Isotopes
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Enterotoxins
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Excitatory Amino Acid Agonists
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TSCL protein, Arabidopsis
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Toxins, Biological
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tcdA protein, Clostridium difficile
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gamma-Aminobutyric Acid
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Asparagine
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alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid
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ral GTP-Binding Proteins
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Glucose
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Alanine