The G protein alpha chaperone and guanine-nucleotide exchange factor RIC-8 regulates cilia morphogenesis in < i > Caenorhabditis elegans < /i > sensory neurons

by Christina M. Campagna, Hayley McMahon, Inna Nechipurenko Heterotrimeric G ( αβγ) proteins are canonical transducers of G-protein-coupled receptor (GPCR) signaling and play critical roles in communication between cells and their environment. Many GPCRs and heterotrimeric G proteins localize to primary cilia and modulate cilia morphology via mechanisms that are not well un derstood. Here, we show that RIC-8, a cytosolic guanine nucleotide exchange factor (GEF) and chaperone for Gα protein subunits, shapes cilia membrane morphology in a subset ofCaenorhabditis elegans sensory neurons. Consistent with its role in ciliogenesis,C.elegans RIC-8 localizes to cilia in different sensory neuron types. Using domain mutagenesis, we demonstrate that while the GEF function alone is not sufficient, both the GEF and G α-interacting chaperone motifs of RIC-8 are required for its role in cilia morphogenesis. We identify ODR-3 as the RIC-8 Gα client and demonstrate that RIC-8 functions in the same genetic pathway with another component of the non-canonical G protein signaling AGS-3 to shape cilia morphology. Notab ly, despite defects in AWC cilia morphology,ags-3 null mutants exhibit normal chemotaxis toward benzaldehyde unlikeodr-3 mutant animals. Collectively, our findings describe a novel function for the evolutionarily conserved protein RIC-8 and non-canonical RIC-8-AGS-3-ODR-3 signaling in cilia morphogenesis and uncouple G α ODR-3 functions in ciliogenesis and olfaction.
Source: PLoS Genetics - Category: Genetics & Stem Cells Authors: Source Type: research