Galpha(12) and galpha(13) inhibit Ca(2+)-dependent exocytosis through Rho/Rho-associated kinase-dependent pathway.
The release of neurotransmitters is known to be regulated by activation of heterotrimeric G protein-coupled receptors, although precise mechanisms have not yet been elucidated. To assess the role of the G(12) family of heterotrimeric G proteins in the regulation of neurotransmitter release, we established PC12 cell lines that expressed constitutively active Galpha(12) or Galpha(13) using an isopropyl-beta-D-thiogalactoside-inducible expression system. In the cells, expression of constitutively active Galpha(12) or Galpha(13) inhibited the high K(+)-evoked [(3)H]dopamine release without any effect on the high K(+)-induced increase in intracellular Ca(2+) concentration. A Ca(2+) ionophore ionomycin-induced [(3)H]dopamine release was also inhibited by the expression of active Galpha(12) or Galpha(13). These inhibitory effects of Galpha(12) and Galpha(13) on [(3)H]dopamine release were mimicked by the expression of constitutively active RhoA. In addition, Y-27632, and inhibitor of Rho-associated kinase, a downstream Rho effector, completely abolished the inhibition of [(3)H]dopamine release by Galpha(12), Galpha(13), and RhoA. These results indicate that Ca(2+)-dependent exocytosis is regulated by Galpha(12) and Galpha(13) through a Rho/Rho-associated kinase-dependent pathway.
Yamaguchi
Y
Y
Laboratory of Molecular Neurobiology, Graduate School of Biostudies, Kyoto University, Kyoto, Japan.
Katoh
H
H
Yasui
H
H
Aoki
J
J
Nakamura
K
K
Negishi
M
M
D000818:Animals; D002118:Calcium / Q000502:physiology*; D020013:Calcium Signaling; D004298:Dopamine / Q000378:metabolism*; D005089:Exocytosis; D044365:GTP-Binding Protein alpha Subunits, G12-G13; D020962:Heterotrimeric GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D016716:PC12 Cells; D011188:Potassium / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection; D020741:rho GTP-Binding Proteins / Q000378:metabolism*; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
D047908:Intracellular Signaling Peptides and Proteins; D011994:Recombinant Proteins; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D044365:GTP-Binding Protein alpha Subunits, G12-G13; D020962:Heterotrimeric GTP-Binding Proteins; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein; D011188:Potassium; D002118:Calcium; D004298:Dopamine