[
International Worm Meeting,
2021]
Lipopolysaccharides (LPS) of Salmonella enterica serotype typhimurium stimulates egg laying in C. elegansN2 strain. Among the 23 G protein alpha subunits in C. elegans, we found that GPA-11 is a component in the signaling pathway, since the loss-of-function mutant did not respond to LPS stimulation while displaying wildtype stimulated egg-laying response to serotonin. We dissected the mutant hermaphrodites at the adult stage which are usually selected for egg-laying assays and found that they bore similar number of eggs to that of N2 worms. This confirms that the blunted response to LPS egg-laying stimulation in the mutants was not due to any limited number of eggs stored in the uterus, but was because of the absence of functional GPA-11 protein. The mutant was known to respond poorly to the repellent octanol but are wild-type for other traits studied. Therefore, our reported observation reveals another defect of the mutant. Besides, the defective egg-laying response to the bacterial toxin LPS is likely to be linked to innate immunity, so the involvement of the chemosensation-related GPA-11 that is expressed in the chemosensory ASHs and ADL neurons suggests that there is an interaction between chemosensation and innate immune responses. Moreover, GPA-11 is epistatic to TPH-1 involved in serotonin biosynthesis, but the G protein-coupled receptor with which GPA-11 interacts is yet to be identified. The egg-laying system responsive to LPS stimulation may provide insights into this complete signaling pathway. It is also noteworthy that GPA-11 in another Caenorhabditis species, C. briggsae, is dysfunctional because of an altered translation frame resulted from an insertion in the first exon. Future investigation is needed for understanding the possible dispensability of GPA-11 in innate immunity and/or chemosensation in the genus.