G protein-coupled receptor-promoted trafficking of Gbeta1gamma2 leads to AKT activation at endosomes via a mechanism mediated by Gbeta1gamma2-Rab11a interaction

• Published in: Molecular biology of the cell Vol. 19; no. 10; pp. 4188 - 4200
• Main Authors: García-Regalado, Alejandro, Guzmán-Hernández, María Luisa, Ramírez-Rangel, Iliana, Robles-Molina, Evelyn, Balla, Tamas, Vázquez-Prado, José, Reyes-Cruz, Guadalupe
• Format: Journal Article
• Language: English
• Published: United States 01.10.2008
• Subjects: Cell Line; Cell Membrane - metabolism; Cell Proliferation; Cell Survival; Endosomes - metabolism; GTP-Binding Protein beta Subunits - metabolism; GTP-Binding Protein gamma Subunits - metabolism; Humans; Microscopy, Fluorescence - methods; Models, Biological; Mutation; Protein Binding; Proto-Oncogene Proteins c-akt - metabolism; rab GTP-Binding Proteins - metabolism; Receptors, G-Protein-Coupled - metabolism; Two-Hybrid System Techniques
• ISSN: 1939-4586
• DOI: 10.1091/mbc.E07-10-1089

G-protein coupled receptors activate heterotrimeric G proteins at the plasma membrane in which most of their effectors are intrinsically located or transiently associated as the external signal is being transduced. This paradigm has been extended to the intracellular compartments by studies in yeast showing that trafficking of Galpha activates phosphatidylinositol 3-kinase (PI3K) at endosomal compartments, suggesting that vesicle trafficking regulates potential actions of Galpha and possibly Gbetagamma at the level of endosomes. Here, we show that Gbetagamma interacts with Rab11a and that the two proteins colocalize at early and recycling endosomes in response to activation of lysophosphatidic acid (LPA) receptors. This agonist-dependent association of Gbetagamma to Rab11a-positive endosomes contributes to the recruitment of PI3K and phosphorylation of AKT at this intracellular compartment. These events are sensitive to the expression of a dominant-negative Rab11a mutant or treatment with wortmannin, suggesting that Rab11a-dependent Gbetagamma trafficking promotes the activation of the PI3K/AKT signaling pathway associated with endosomal compartments. In addition, RNA interference-mediated Rab11a depletion, or expression of a dominant-negative Rab11a mutant attenuated LPA-dependent cell survival and proliferation, suggesting that endosomal activation of the PI3K/AKT signaling pathway in response to Gbetagamma trafficking, via its interaction with Rab11, is a relevant step in the mechanism controlling these fundamental events.