Effects of a Caenorhabditis elegans Dauer Pheromone Ascaroside on Physiology and Signal Transduction Pathways
Daumone is one of the three purified and artificially synthesized components of the Caenorhabditis elegans dauer pheromone. It affects the major signal transduction pathways known to discriminate between developmental arrest at the dauer stage and growth to the adult [the transforming growth factor beta (TGF-β) and daf-2/IGF1R pathways], just as natural pheromone extracts do. Transcription of daf-7/TGF-β is reduced in pre-dauer larvae, and nuclear localization of the DAF-16/FOXO transcription factor is increased in embryos and L1 larvae exposed to synthetic daumone. However, daumone does not require the cilia in the amphidial neurons to produce these effects nor does it require the Gα protein GPA-3 to induce dauer entry, although GPA-3 is required for dauer induction by natural dauer pheromone extracts. Synthetic daumone has physiological effects that have not been observed with natural pheromone. It is toxic at the concentrations required for bioassay and is lethal to mutants with defective cuticles. The molecular and physiological effects of daumone and natural dauer pheromone are only partially overlapping.
KeywordsASI neurons ASJ neurons Caenorhabditis elegans DAF-16 Dauer Dauer pheromone Daumone Gene expression Insulin signaling Physiology TGF-β Transcription
We thank Victor Jensen, Nigel O’Neil, and Donha Park for helpful discussions. Some nematode strains used in this work were provided by the Caenorhabditis Genetics Center, which is funded by the NIH National Center for Research Resources (NCRR). This work was supported by the Cordula and Gunter Paetzold University Graduate Fellowship and a Michael Smith Foundation for Health Research Senior Graduate Studentship to M.G. and the Canadian Institutes of Health Research (MOP 79458) to D.L.R.
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