title: Regulation of a hitchhiking behavior by neuronal insulin and TGF-β signaling in the nematode Caenorhabditis elegans.
abstract: Free-living nematode Caenorhabditis elegans exhibits various behaviors to adapt to the fluctuating environment. When early larvae of C. elegans experience the harsh environmental condition, they develop to an alternative developmental stage called dauer, which shows nictation, a stage-specific waving behavior. Nictation enables dauers to attach to more mobile animals, which helps them disperse to other habitats beyond physical barriers. However, underlying molecular mechanisms that regulate nictation behavior are largely unknown. In this study, we show that insulin signaling and transforming growth beta (TGF-β) signaling, the two major parallel signaling pathways that mediate dauer development, are involved in the regulation of dauer-specific nictation behavior. Genetic analysis revealed that downregulation of insulin signaling enhanced nictation behavior. Heat-shock induced rescue experiments showed that the action period of the insulin signaling is before dauer formation. Surprisingly, lowering of TGF-β signaling inhibited the normal performance of nictation, suggesting that TGF-β signaling acts in an opposite way from that for dauer formation. Cell-specific rescue experiments revealed that two signaling pathways act in the nervous system and an epistasis experiment showed that TGF-β signaling is epistatic to insulin signaling. Taken together, we propose that the neuroendocrinal insulin signaling and TGF-β signaling regulate nictation behavior during development in response to environmental conditions.
authors.affiliation: Institute of Molecular Biology and Genetics, Department of Biological Sciences, Seoul National University, Seoul, South Korea.
authors.forename: Daehan
authors.initials: D
authors.lastname: Lee
authors.affiliation: Institute of Molecular Biology and Genetics, Department of Biological Sciences, Seoul National University, Seoul, South Korea.
authors.forename: Harksun
authors.initials: H
authors.lastname: Lee
authors.affiliation: Institute of Molecular Biology and Genetics, Department of Biological Sciences, Seoul National University, Seoul, South Korea.
authors.forename: Nari
authors.initials: N
authors.lastname: Kim
authors.affiliation: Institute of Molecular Biology and Genetics, Department of Biological Sciences, Seoul National University, Seoul, South Korea.
authors.forename: Daisy S
authors.initials: DS
authors.lastname: Lim
authors.affiliation: Institute of Molecular Biology and Genetics, Department of Biological Sciences, Seoul National University, Seoul, South Korea. Electronic address: elegans@snu.ac.kr.
authors.forename: Junho
authors.initials: J
authors.lastname: Lee
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D015398:Signal Transduction; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D054462:p21-Activated Kinases / Q000378:metabolism
chemical_list: D029742:Caenorhabditis elegans Proteins; C102095:DAF-7 protein, C elegans; D007328:Insulin; D016212:Transforming Growth Factor beta; D054462:p21-Activated Kinases
keywords: C. elegans; Dauer; Insulin signaling; Nictation behavior; Signaling pathway; TGF-β signaling