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A Gα12-specific Binding Domain in AKAP-Lbc and p114RhoGEF
Joseph W Martin1, Kyle S Cavagnini1, Douglas N Brawley1
1Department of Biology, University of North Carolina Asheville, One University Heights, Asheville NC 28804, USA.
Journal of Molecular Signaling
|May 4, 2019
Summary
AKAP-Lbc and p114RhoGEF bind Gα12 via a novel mechanism, distinct from RH-domain interactions. This identifies a new signaling pathway for Gα12 activation of non-RH RhoGEFs.
Area of Science:
- Molecular Biology
- Cell Signaling
- Cardiovascular Research
Background:
- AKAP-Lbc is a Rho-activating guanine nucleotide exchange factor (RhoGEF) crucial for heart development and fibrosis.
- Heterotrimeric G proteins Gα12/13 activate RhoGEFs via their RGS-homology (RH) domain.
- AKAP-Lbc, lacking an RH domain, binds Gα12 through an undefined mechanism.
Purpose of the Study:
- To elucidate the mechanism by which Gα12 binds and activates AKAP-Lbc.
- To identify the Gα12-binding region in AKAP-Lbc and related RhoGEFs.
- To characterize the specificity and cellular relevance of this novel interaction.
Main Methods:
- Site-directed mutagenesis of Gα12 and RhoGEFs.
- Co-immunoprecipitation assays to assess protein binding.
- Cellular signaling assays to evaluate Rho pathway activation.
- Analysis of chimeric G12/13 α subunits to map selectivity determinants.
Main Results:
- A novel Gα12-binding region was identified near the C-terminus of AKAP-Lbc, also present in p114RhoGEF.
- This binding mechanism is distinct from RH-domain interactions, as shown by mutant Gα12 selectivity.
- AKAP-Lbc and p114RhoGEF exhibit high specificity for Gα12 over Gα13.
- Gα12 demonstrated a more potent dominant-negative effect on p114RhoGEF signaling compared to Gα13 in cultured cells.
Conclusions:
- p114RhoGEF is identified as a novel Gα12 signaling effector.
- A conserved region in AKAP-Lbc and p114RhoGEF mediates Gα12 binding, defining a new signaling input pathway.
- This discovery provides insight into Gα12-mediated signaling in non-RH RhoGEFs, relevant to cardiovascular biology.
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