GPCR Signaling in C. elegans and Its Implications in Immune Response

The ability to sense environmental cues is central to the survival of living organisms. G-protein-coupled receptors (GPCRs) are, by far, the most diverse class of sensory receptors and play an important role in surveillance. As Caenorhabditis elegans lives in soil and feeds on bacteria, it must have strategies to differentiate between nutritious vs pathogenic bacteria. In C. elegans, lacking professional immune cells, GPCRs play a very important role in defense responses, for survival against pathogens. Here, we review a rich body of research to show that C. elegans uses GPCRs in different tissues for immune surveillance, immune homeostasis, as well as behavioral responses. Nematode sensory neurons and GPCRs can sense both pathogen-associated molecules as well as damage-associated molecular patterns during infection. Both fight and flight responses, activated upon exposure to pathogens, are driven by GPCRs and trimeric G proteins in the sensory neurons.