Selective Uncoupling of Gα12 from Rho-mediated Signaling

The heterotrimeric G protein G12 has been implicated in such cellular regulatory processes as cytoskeletal rearrangement, cell-cell adhesion, and oncogenic transformation. Although the activated α-subunit of G12 has been shown to interact directly with a number of protein effectors, the roles of man...

Full description

Saved in:
Bibliographic Details
Published inThe Journal of biological chemistry Vol. 280; no. 18; pp. 18049 - 18055
Main Authors Meigs, Thomas E., Juneja, Juhi, DeMarco, C. Todd, Stemmle, Laura N., Kaplan, Daniel D., Casey, Patrick J.
Format Journal Article
LanguageEnglish
Published Elsevier Inc 01.05.2005
Online AccessGet full text

Cover

Loading…
More Information
Summary:The heterotrimeric G protein G12 has been implicated in such cellular regulatory processes as cytoskeletal rearrangement, cell-cell adhesion, and oncogenic transformation. Although the activated α-subunit of G12 has been shown to interact directly with a number of protein effectors, the roles of many of these protein-protein interactions in G12-mediated cell physiology are poorly understood. To begin dissecting the specific cellular pathways engaged upon G12 activation, we produced a series of substitution mutants in the regions of Gα12 predicted to play a role in effector binding. Here we report the identification and characterization of an altered form of Gα12 that is functionally uncoupled from signaling through the monomeric G protein Rho, a protein known to propagate several Gα12-mediated signals. This mutant of Gα12 fails to bind the Rho-specific guanine nucleotide exchange factors p115RhoGEF and LARG (leukemia-associated RhoGEF), fails to stimulate Rho-dependent transcriptional activation, and fails to trigger activation of RhoA and the Rho-mediated cellular responses of cell rounding and c-jun N-terminal kinase activation. Importantly, this mutant of Gα12 retains coupling to the effector protein E-cadherin, as evidenced by its ability both to bind E-cadherin in vitro and to disrupt E-cadherin-mediated cell-cell adhesion. Furthermore, this mutant retains the ability to trigger β-catenin release from the cytoplasmic domain of cadherin. This identification of a variant of Gα12 that is selectively uncoupled from one signaling pathway while retaining signaling capacity through a separate pathway will facilitate investigations into the mechanisms through which G12 proteins mediate diverse biological responses.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M500445200