ERK/MAPK regulates ecdysteroid and sorbitol metabolism for embryonic diapause termination in the silkworm, Bombyx mori.
The eggs of the silkworm Bombyx mori undergo a state of suspended overt development and diminished metabolism called "diapause" to escape adverse environmental conditions. Termination of Bombyx embryonic diapause requires 2-3 months of low temperature (5 degrees C), but the molecular mechanisms underlying diapause termination are unknown. Diapause termination requires a decrease in the sorbitol concentration, which arrests embryonic development, and the secretion factors from yolk cells that promote embryonic development. In the present study, we report that 20-hydroxyecdysone promoted the development of denuded embryos and that ecdysteroid-phosphate phosphatase (EPPase), which is a key enzyme for active ecdysteroid production, was induced by incubation of diapausing eggs at 5 degrees C. In dechorionated egg cultures, extracellular signal-regulated kinase (ERK), which is activated by incubating diapausing eggs at 5 degrees C, regulated sorbitol-glycogen conversion, ecdysteroid secretion via gene transcription of key enzymes, sorbitol dehydrogenase-2, and EPPase, suggesting that ERK has a key role in diapause termination.
Department of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, Ueda, Nagano 386-8567, Japan. yoshihiro.fujiwara@nifty.com
Yoshihiro
Y
Fujiwara
Yoshiaki
Y
Tanaka
Ken-ichi
K
Iwata
Raquel O
RO
Rubio
Toshinobu
T
Yaginuma
Okitsugu
O
Yamashita
Kunihiro
K
Shiomi
D000818:Animals; D012831:Bombyx / Q000196:embryology* / Q000378:metabolism / Q000502:physiology; D003080:Cold Temperature; D026461:Ecdysteroids / Q000378:metabolism* / Q000502:physiology; D004441:Ecdysterone / Q000502:physiology; D004530:Egg Yolk / Q000502:physiology; D047108:Embryonic Development / Q000502:physiology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000502:physiology*; D005260:Female; D015870:Gene Expression; D006003:Glycogen / Q000096:biosynthesis; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D013012:Sorbitol / Q000378:metabolism*
D026461:Ecdysteroids; D013012:Sorbitol; D004441:Ecdysterone; D006003:Glycogen; D048049:Extracellular Signal-Regulated MAP Kinases; C476613:ecdysteroid-phosphate phosphatase; D010744:Phosphoric Monoester Hydrolases