Prenylation-deficient G protein gamma subunits disrupt GPCR signaling in the zebrafish

Prenylation of G protein gamma (gamma) subunits is necessary for the membrane localization of heterotrimeric G proteins and for functional heterotrimeric G protein coupled receptor (GPCR) signaling. To evaluate GPCR signaling pathways during development, we injected zebrafish embryos with mRNAs encoding G gamma subunits mutated so that they can no longer be prenylated. Low-level expression of these prenylation-deficient G gamma subunits driven either ubiquitously or specifically in the primordial germ cells (PGCs) disrupts GPCR signaling and manifests as a PGC migration defect. This disruption results in a reduction of calcium accumulation in the protrusions of migrating PGCs and a failure of PGCs to directionally migrate. When co-expressed with a prenylation-deficient G gamma, 8 of the 17 wildtype G gamma isoforms individually confer the ability to restore calcium accumulation and directional migration. These results suggest that while the G gamma subunits possess the ability to interact with G Beta (beta) proteins, only a subset of wildtype G gamma proteins are stable within PGCs and can interact with key signaling components necessary for PGC migration. This in vivo study highlights the functional redundancy of these signaling components and demonstrates that prenylation-deficient G gamma subunits are an effective tool to investigate the roles of GPCR signaling events during vertebrate development. (C) 2009 Elsevier Inc. All rights reserved.