G o α regulates olfactory adaptation by antagonizing G q α-DAG signaling in Caenorhabditis elegans

The heterotrimeric G protein Go is abundantly expressed in the mammalian nervous system and modulates neural activities in response to various ligands. However, Go 's functions in living animals are less well understood. Here, we demonstrate that GOA-1 Go α has a fundamental role in olfactory adaptation inCaenorhabditis elegans . Impairment of GOA-1 Go α function and excessive activation of EGL-30 Gq α cause a defect in adaptation to AWC-sensed odorants. These pathways antagonistically modulate olfactory adaptation in AWC chemosensory neurons. Wild-type animals treated with phorbol esters and double-mutant animals of diacylglycerol (DAG) kinases,dgk-3 ;dgk-1 , also have a defect in adaptation, suggesting that elevated DAG signals disrupt normal adaptation. Constitutively active GOA-1 can suppress the adaptation defect ofdgk-3 ;dgk-1 double mutants, whereas it fails to suppress the adaptation defect of animals with constitutively active EGL-30, implying that GOA-1 acts upstream of EGL-30 in olfactory adaptation. Our results suggest that down-regulation of EGL-30–DAG signaling by GOA-1 underlies olfactory adaptation and plasticity of chemotaxis.