Selective uncoupling of G alpha 12 from Rho-mediated signaling.


Journal Article

The heterotrimeric G protein G(12) has been implicated in such cellular regulatory processes as cytoskeletal rearrangement, cell-cell adhesion, and oncogenic transformation. Although the activated alpha-subunit of G(12) has been shown to interact directly with a number of protein effectors, the roles of many of these protein-protein interactions in G(12)-mediated cell physiology are poorly understood. To begin dissecting the specific cellular pathways engaged upon G(12) activation, we produced a series of substitution mutants in the regions of Galpha(12) predicted to play a role in effector binding. Here we report the identification and characterization of an altered form of Galpha(12) that is functionally uncoupled from signaling through the monomeric G protein Rho, a protein known to propagate several Galpha(12)-mediated signals. This mutant of Galpha(12) 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 Galpha(12) 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 beta-catenin release from the cytoplasmic domain of cadherin. This identification of a variant of Galpha(12) that is selectively uncoupled from one signaling pathway while retaining signaling capacity through a separate pathway will facilitate investigations into the mechanisms through which G(12) proteins mediate diverse biological responses.

Full Text

Duke Authors

Cited Authors

  • Meigs, TE; Juneja, J; DeMarco, CT; Stemmle, LN; Kaplan, DD; Casey, PJ

Published Date

  • May 6, 2005

Published In

Volume / Issue

  • 280 / 18

Start / End Page

  • 18049 - 18055

PubMed ID

  • 15746095

Pubmed Central ID

  • 15746095

International Standard Serial Number (ISSN)

  • 0021-9258

Digital Object Identifier (DOI)

  • 10.1074/jbc.M500445200


  • eng

Conference Location

  • United States