Homo- and hetero-oligomerization of PDZ-RhoGEF, LARG and p115RhoGEF by their C-terminal region regulates their in vivo Rho GEF activity and transforming potential

Oncogene. 2004 Jan 8;23(1):233-40. doi: 10.1038/sj.onc.1207012.

Abstract

PDZ-RhoGEF, LARG, and p115RhoGEF are members of a newly identified family of Rho-guanine nucleotide exchange factors (GEFs) exhibiting a unique structural feature consisting of the presence of an area of similarity to regulators of G protein signaling (RGS). This RGS-like (RGL) domain provides a functional motif by which Galpha(12) and Galpha(13) can bind and regulate the activity of these RhoGEFs, thus providing a direct link from these heterotrimeric G proteins to Rho. PDZ-RhoGEF and LARG can also be phosphorylated by tyrosine kinases, including FAK, and associate with Plexin B, a semaphorin receptor, which controls axon guidance during development, through their PDZ domain, thereby stimulating Rho. Interestingly, while characterizing a PDZ-RhoGEF antiserum, we found that a transfected PDZ-RhoGEF construct associated with the endogenous PDZ-RhoGEF. Indeed, we observed that PDZ-RhoGEF and LARG can form homo- and hetero-oligomers, whereas p115RhoGEF can only homo-oligomerize, and that this intermolecular interaction was mediated by their unique C-terminal regions. Deletion of the C-terminal tail of PDZ-RhoGEF had no significant effect on the GEF catalytic activity towards Rho in vitro, but resulted in a drastic increase in the ability to stimulate a serum response element reporter and the accumulation of the GTP-bound Rho in vivo. Furthermore, removal of the C-termini of each of the three RGL-containing GEFs unleashed their full transforming potential. Together, these findings suggest the existence of a novel mechanism controlling the activity of PDZ-RhoGEF, LARG, and p115RhoGEF, which involves homo- and hetero-oligomerization through their inhibitory C-terminal region.

MeSH terms

  • Animals
  • Cell Line
  • Cell Transformation, Neoplastic*
  • Guanine Nucleotide Exchange Factors / chemistry*
  • Guanine Nucleotide Exchange Factors / physiology
  • Humans
  • Mice
  • NIH 3T3 Cells
  • Phosphorylation
  • Receptors, Glutamate / chemistry*
  • Receptors, Glutamate / physiology
  • Rho Guanine Nucleotide Exchange Factors
  • Structure-Activity Relationship

Substances

  • ARHGEF11 protein, human
  • ARHGEF12 protein, human
  • Arhgef12 protein, mouse
  • Guanine Nucleotide Exchange Factors
  • Receptors, Glutamate
  • Rho Guanine Nucleotide Exchange Factors