In vitro and in vivo stimulation of extracellular signal-regulated kinase (ERK) by the prothoracicotropic hormone in prothoracic gland cells and its developmental regulation in the silkworm, Bombyx mori.
In this study, we investigated activation of the extracellular signal-regulated kinase (ERK) by the prothoracicotropic hormone (PTTH) in prothoracic gland cells of the silkworm, Bombyx mori. The results showed that the PTTH stimulated ERK phosphorylation as this depends on time and dose and ecdysteroidogenic activity. The ERK phosphorylation inhibitors, PD 98059 and U0126, blocked both basal and PTTH-stimulated ERK phosphorylation and ecdysteroidogenesis. In addition, activation of glandular ERK phosphorylation by the PTTH appeared to be developmentally regulated with the refractoriness of gland cells to the PTTH occurring during the latter stages of both the fourth and last larval instars. Moreover, in vitro activation of ERK phosphorylation of prothoracic glands by the PTTH was also verified by in vivo experiments: injection of the PTTH into day 6 last instar larvae greatly increased the activity of glandular ERK phosphorylation and ecdysteroidogenesis. These results suggest that development-specific changes in ERK phosphorylation may play a role in PTTH stimulation of ecdysteroidogenesis.
Lin
Ju-Ling
JL
Department of Zoology, National Museum of Natural Science, 1 Kuan Chien Road, Taichung 404, Taiwan, ROC.
Gu
Shi-Hong
SH
D000818:Animals; D012831:Bombyx / Q000201:enzymology / Q000502:physiology*; D002070:Butadienes / Q000494:pharmacology; D026461:Ecdysteroids / Q000096:biosynthesis*; D004702:Endocrine Glands / Q000201:enzymology / Q000502:physiology; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D005419:Flavonoids / Q000494:pharmacology; D007301:Insect Hormones / Q000502:physiology*; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology
D002070:Butadienes; D026461:Ecdysteroids; D005419:Flavonoids; D007301:Insect Hormones; D009570:Nitriles; D047428:Protein Kinase Inhibitors; C113580:U 0126; C009089:prothoracicotropic hormone; D048049:Extracellular Signal-Regulated MAP Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one