Gi/o GPCRs drive the formation of actin-rich tunneling nanotubes in cancer cells via a Gβγ/PKCα/FARP1/Cdc42 axis

Abstract

"The functional association between stimulation of G-protein coupled receptors (GPCRs) by eicosanoids and actin cytoskeleton reorganization remains largely unexplored. Using a model of human adrenocortical cancer cells, here we established that activation of the GPCR OXER1 by its natural agonist, the eicosanoid 5-oxo-eicosatetraenoic acid (5-oxo-ETE), leads to the formation of filopodia-like elongated projections connecting adjacent cells, known as tunneling nanotube (TNT)-like structures. This effect is reduced by pertussis toxin (PTX) and GUE1654, a biased antagonist for the Gβγ pathway downstream of OXER1 activation. We also observed PTX-dependent TNT biogenesis in response to lysophosphatidic acid (LPA), indicative of a general response driven by Gi/o-coupled GPCRs. TNT generation by either 5-oxo-ETE or LPA is partially dependent on the transactivation of the epidermal growth factor receptor (EGFR) and impaired by PI3K inhibition. Subsequent signaling analysis reveals a strict requirement of phospholipase C β3 (PLCβ3) and its downstream effector PKCα. Consistent with the established role of Rho small GTPases in the formation of actin-rich projecting structures, we identified the PI3K-regulated guanine nucleotide exchange factor (GEF) FARP1 as a GPCR effector essential for TNT formation, acting via Cdc42. Altogether, our study pioneers a link between Gi/o-coupled GPCRs and TNT development, and sheds light into the intricate signaling pathways governing the generation of specialized actin-rich elongated structures in response to bioactive signaling lipids."