The Journal Of Biological Chemistry
After activation of G protein–coupled receptors, G protein βγ dimers may translocate from the plasma membrane to the Golgi apparatus (GA). We recently report that this translocation activates extracellular signal–regulated protein kinases 1 and 2 (ERK1/2) via PI3Kγ; however, how Gβγ–PI3Kγ activates the ERK1/2 pathway is unclear. Here, we demonstrate that chemokine receptor CXCR4 activates ADP-ribosylation factor 1 (ARF1), a small GTPase important for vesicle-mediated membrane trafficking. This activation is blocked by CRISPR–Cas9-mediated knockout of the GA-translocating Gγ9 subunit. Inducible targeting of different Gβγ dimers to the GA can directly activate ARF1. CXCR4 activation and constitutive Gβγ recruitment to the GA also enhance ARF1 translocation to the GA. We further demonstrate that pharmacological inhibition and CRISPR–Cas9-mediated knockout of PI3Kγ markedly inhibit CXCR4-mediated and Gβγ translocation–mediated ARF1 activation. We also show that depletion of ARF1 by siRNA and CRISPR–Cas9 and inhibition of GA-localized ARF1 activation abolish ERK1/2 activation by CXCR4 and Gβγ translocation to the GA and suppress prostate cancer PC3 cell migration and invasion. Collectively, our data reveal a novel function for Gβγ translocation to the GA to activate ARF1 and identify GA-localized ARF1 as an effector acting downstream of Gβγ–PI3Kγ to spatiotemporally regulate G protein–coupled receptor signaling to mitogen-activated protein kinases.