title: MET is required for the maximal action of 20-hydroxyecdysone during Bombyx metamorphosis.
abstract: Little is known about how the putative juvenile hormone (JH) receptor, the bHLH-PAS transcription factor MET, is involved in 20-hydroxyecdysone (20E; the molting hormone) action. Here we report that two MET proteins found in the silkworm, Bombyx mori, participate in 20E signal transduction. Met is 20E responsive and its expression peaks during molting and pupation, when the 20E titer is high. As found with results from RNAi knockdown of EcR-USP (the ecdysone receptor genes), RNAi knockdown of Met at the early wandering stage disrupts the 20E-triggered transcriptional cascade, preventing tissue remodeling (including autophagy, apoptosis and destruction of larval tissues and generation of adult structures) and causing lethality during the larval-pupal transition. MET physically interacts with EcR-USP. Moreover, MET, EcR-USP and the 20E-response element (EcRE) form a protein-DNA complex, implying that MET might modulate 20E-induced gene transcription by interacting with EcR-USP. In conclusion, the 20E induction of MET is required for the maximal action of 20E during Bombyx metamorphosis.
authors.affiliation: Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Enen
authors.initials: E
authors.lastname: Guo
authors.forename: Qianyu
authors.initials: Q
authors.lastname: He
authors.forename: Shumin
authors.initials: S
authors.lastname: Liu
authors.forename: Ling
authors.initials: L
authors.lastname: Tian
authors.forename: Zhentao
authors.initials: Z
authors.lastname: Sheng
authors.forename: Qin
authors.initials: Q
authors.lastname: Peng
authors.forename: Jingmin
authors.initials: J
authors.lastname: Guan
authors.forename: Mingan
authors.initials: M
authors.lastname: Shi
authors.forename: Kang
authors.initials: K
authors.lastname: Li
authors.forename: Lawrence I
authors.initials: LI
authors.lastname: Gilbert
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Yang
authors.initials: Y
authors.lastname: Cao
authors.forename: Sheng
authors.initials: S
authors.lastname: Li
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D012831:Bombyx / Q000502:physiology*; D004441:Ecdysterone / Q000235:genetics / Q000378:metabolism*; D007605:Juvenile Hormones / Q000235:genetics / Q000378:metabolism*; D008675:Metamorphosis, Biological / Q000235:genetics*; D018978:Molting / Q000235:genetics
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D004441:Ecdysterone; D007605:Juvenile Hormones