A molecular mechanism to diversify Ca2+ signaling downstream of Gs protein-coupled receptors
Julian Brands, Sergi Bravo, Lars Jürgenliemke, Lukas Grätz, Hannes Schihada, Fabian Frechen, Judith Alenfelder, Cy Pfeil, Paul Georg Ohse, Suzune Hiratsuka, Kouki Kawakami, Luna C. Schmacke, Nina Heycke, Asuka Inoue, Gabriele M. König, Alexander Pfeifer, Dagmar Wachten, Gunnar Schulte, Torsten Steinmetzer, Val J. Watts, Jesús Gomeza, Katharina Simon, Evi Kostenis
Abstract
Abstract A long-held tenet in inositol-lipid signaling is that cleavage of membrane phosphoinositides by phospholipase Cβ (PLCβ) isozymes to increase cytosolic Ca 2+ in living cells is exclusive to Gq- and Gi-sensitive G protein-coupled receptors (GPCRs). Here we extend this central tenet and show that Gs-GPCRs also partake in inositol-lipid signaling and thereby increase cytosolic Ca 2+ . By combining CRISPR/Cas9 genome editing to delete Gα s , the adenylyl cyclase isoforms 3 and 6, or the PLCβ1-4 isozymes, with pharmacological and genetic inhibition of Gq and G11, we pin down Gs-derived Gβγ as driver of a PLCβ2/3-mediated cytosolic Ca 2+ release module. This module does not require but crosstalks with Gα s -dependent cAMP, demands Gα q to release PLCβ3 autoinhibition, but becomes Gq-independent with mutational disruption of the PLCβ3 autoinhibited state. Our findings uncover the key steps of a previously unappreciated mechanism utilized by mammalian cells to finetune their calcium signaling regulation through Gs-GPCRs.