RT Journal Article
SR Electronic
T1 The Monomeric G-Proteins Rac1 and/or Cdc42 Are Required for the Inhibition of Voltage-Dependent Calcium Current by Bradykinin
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 4094
OP 4100
DO 10.1523/JNEUROSCI.17-11-04094.1997
VO 17
IS 11
A1 Malgorzata A. Wilk-Blaszczak
A1 William D. Singer
A1 Timothy Quill
A1 Billy Miller
A1 Jeffrey A. Frost
A1 Paul C. Sternweis
A1 Francesco Belardetti
YR 1997
UL http://www.jneurosci.org/content/17/11/4094.abstract
AB Although regulation of voltage-dependent calcium current (ICa,V) by neurotransmitters is a ubiquitous mechanism among nerve cells, the signaling pathways involved are not well understood. We have determined previously that in a neuroblastoma-glioma hybrid cell line (NG108-15), the heterotrimeric G-protein G13 mediates the inhibition ofICa,V produced by bradykinin (BK) via an unknown mechanism. Various reports indicate that G13 can couple to RhoA, Rac1, and Cdc42, which are closely related members of the Rho family of monomeric G-proteins. We have investigated their role as signaling intermediates in the pathway used by BK to inhibitICa,V. Using immunoblot analysis and the PCR, we found evidence that RhoA, Rac1, and Cdc42 all are expressed in NG108-15 cells. Intracellularly perfused recombinant Rho-GDI (an inhibitor of guanine nucleotide exchange specific for the Rho family) attenuated the inhibition of ICa,V by BK. These findings indicate that activation of RhoA, Rac1, or Cdc42 may be required for the response to BK. To determine whether any of these monomeric G-proteins mediate the response to BK, we have intracellularly applied blocking antibodies specific for each of the candidate proteins. Only the anti-Rac1 antibody blocked the response to BK. In parallel experiments, peptides corresponding to the C-terminal regions of Rac1 and Cdc42 blocked the same response. These data indicate a novel functional contribution of Rac1 and possibly also of Cdc42 to the inhibition of ICa,V by neurotransmitters.