A GDP/GTP exchange protein for the Rab3 small G protein family up-regulates a postdocking step of synaptic exocytosis in central synapses.
The Rab3 GDP/GTP exchange protein (Rab3 GEP) activates the Rab3 small GTP-binding protein (G protein) family, including Rab3A that is an important member controlling synaptic vesicle trafficking. Here, we examined the role of Rab3 GEP in regulating neurotransmitter release in autapses of mouse hippocampal neurons in culture. The release probability was markedly reduced in Rab3 GEP-/- neurons, whereas the readily releasable pool size was not different between WT and Rab3 GEP-/- neurons, indicating that Rab3 GEP up-regulates a postdocking step of synaptic exocytosis. Because Rab3A reportedly down-regulates Ca(2+)-triggered fusion of synaptic vesicles, these results provide evidence for a role of Rab3 GEP in the postdocking process distinct from Rab3A activation.
Yamaguchi
Kazuhiko
K
Laboratory for Memory and Learning, Brain Science Institute (BSI), Institute of Physical and Chemical Research (RIKEN), Saitama 351-0198, Japan.
Tanaka
Miki
M
Mizoguchi
Akira
A
Hirata
Yoshihiro
Y
Ishizaki
Hiroyoshi
H
Kaneko
Kumi
K
Miyoshi
Jun
J
Takai
Yoshimi
Y
D000818:Animals; D002118:Calcium / Q000378:metabolism; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology*; D005089:Exocytosis; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000502:physiology*; D006624:Hippocampus / Q000166:cytology; D051379:Mice; D018345:Mice, Knockout; D009474:Neurons / Q000502:physiology; D013569:Synapses; D015854:Up-Regulation; D020692:rab3 GTP-Binding Proteins / Q000378:metabolism*
D020662:Guanine Nucleotide Exchange Factors; D020692:rab3 GTP-Binding Proteins; D002118:Calcium