The genetic model of the nematode Caenorhabditis elegans once again proves its usefulness in determining functions for individual members of large protein families. This time, the function of the regulators of G protein signaling (RGS) that promote guanosine triphosphatase (GTPase) activity of G proteins in vitro were analyzed in vivo using genetic methods to overexpress or delete the genes of interest. Dong et al. demonstrate that three different RGS proteins control egg-laying behavior by regulating signaling through Gα0 that inhibits egg laying. A fourth RGS was previously known to regulate egg laying by influencing a Gαq pathway that promotes egg laying. Genetic analysis confirmed that rgs-1, rgs-2, and a third RGS gene called egl-10 all interacted with goa-1 to regulate egg laying and locomotor behavior. The regulation of GAO-1 by RGS-1 and RGS-2 was supported by in vitro assays demonstrating that these two RGS proteins could stimulate GOA-1 GTPase activity and the fact that all three proteins were expressed by the same neurons. Most interestingly, the authors show that EGL-10 controls egg laying under well-fed conditions, and RGS-1 and RGS-2 redundantly control the resumption of egg laying after periods of starvation. Thus, multiple RGS proteins regulate a single G protein target to fine-tune the system to be able to respond to environmental changes.
Dong, M.-Q., Chase, D., Patikoglou, G.A., and Koelle, M.R. (2000) Multiple RGS proteins alter neural G protein signaling to allow C. elegans to rapidly change behavior when fed. Genes Dev. 14: 2003-2014. [Abstract] [Full Text]