EcR expression in the prothoracicotropic hormone-producing neurosecretory cells of the Bombyx mori brain

FEBS J. 2006 Aug;273(16):3861-8. doi: 10.1111/j.1742-4658.2006.05398.x.


The steroid hormone 20-hydroxyecdysone (20E) initiates insect molting and metamorphosis through binding with a heterodimer of two nuclear receptors, the ecdysone receptor (EcR) and ultraspiracle (USP). Expression of the specific isoforms EcR-A and EcR-B1 governs steroid-induced responses in the developing cells of the silkworm Bombyx mori. Here, analysis of EcR-A and EcR-B1 expression during larval-pupal development showed that both genes were up-regulated by 20E in the B. mori brain. Whole-mount in situ hybridization and immunohistochemistry revealed that EcR-A and EcR-B1 mRNAs and proteins were exclusively located in two pairs of lateral neurosecretory cells in the larval brain known as the prothoracicotropic hormone (PTTH)- producing cells (PTPCs). In the pupal brain, EcR-A and EcR-B1 expression was detected in tritocerebral cells and optic lobe cells in addition to PTPCs. As PTTH controls ecdysone secretion by the prothoracic gland, these results indicate that 20E-responsive PTPCs are the master cells of insect metamorphosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bombyx / growth & development
  • Bombyx / physiology*
  • Brain / cytology
  • Brain / metabolism*
  • Ecdysterone / pharmacology
  • Gene Expression Regulation, Developmental*
  • Insect Hormones / metabolism*
  • Life Cycle Stages
  • Protein Isoforms / classification
  • Protein Isoforms / drug effects
  • Protein Isoforms / metabolism
  • Receptors, Steroid / classification
  • Receptors, Steroid / drug effects
  • Receptors, Steroid / metabolism*
  • Up-Regulation


  • Insect Hormones
  • Protein Isoforms
  • Receptors, Steroid
  • ecdysone receptor
  • Ecdysterone
  • prothoracicotropic hormone