Differential Inhibitor of Gβγ Signaling to AKT and ERK Derived from Phosducin-like Protein: EFFECT ON SPHINGOSINE 1-PHOSPHATE-INDUCED ENDOTHELIAL CELL MIGRATION AND IN VITRO ANGIOGENESIS

Abstract

Differential inhibitors of Gbetagamma-effector regions are required to dissect the biological contribution of specific Gbetagamma-initiated signaling pathways. Here, we characterize PhLP-M1-G149, a Gbetagamma-interacting construct derived from phosducin-like protein 1 (PhLP) as a differential inhibitor of Gbetagamma, which, in endothelial cells, prevented sphingosine 1-phosphate-induced phosphorylation of AKT, glycogen synthase kinase 3beta, cell migration, and tubulogenesis, while having no effect on ERK phosphorylation or hepatocyte growth factor-dependent responses. This construct attenuated the recruitment of phosphoinositide 3-kinase gamma (PI3Kgamma) to the plasma membrane and the signaling to AKT in response to Gbetagamma overexpression. In coimmunoprecipitation experiments, PhLP-M1-G149 interfered with the interaction between PI3Kgamma and Gbetagamma. Other PhLP-derived constructs interacted with Gbetagamma but were not effective inhibitors of Gbetagamma signaling to AKT or ERK. Our results indicate that PhLP-M1-G149 is a suitable tool to differentially modulate the Gbetagamma-initiated pathway linking this heterodimer to AKT, endothelial cell migration, and in vitro angiogenesis. It can be also useful to further characterize the molecular determinants of the Gbetagamma-PI3Kgamma interaction.