Gβγ translocation to the Golgi apparatus activates ARF1 to spatiotemporally regulate G protein-coupled receptor signaling to MAPK

After activation of G protein-coupled receptors, G protein beta gamma 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 PI3K gamma; however, how G beta gamma-PI3K gamma 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 G gamma 9 subunit. Inducible targeting of different G beta gamma dimers to the GA can directly activate ARF1. CXCR4 activation and constitutive G beta gamma recruitment to the GA also enhance ARF1 translocation to the GA. We further demonstrate that pharmacological inhibition and CRISPR-Cas9-mediated knockout of PI3K gamma markedly inhibit CXCR4-mediated and G beta gamma 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 G beta gamma translocation to the GA and suppress prostate cancer PC3 cell migration and invasion. Collectively, our data reveal a novel function for G beta gamma translocation to the GA to activate ARF1 and identify GA-localized ARF1 as an effector acting downstream of G beta gamma-PI3K gamma to spatiotemporally regulate G protein-coupled receptor signaling to mitogen-activated protein kinases.