EcR expression in the prothoracicotropic hormone-producing neurosecretory cells of the Bombyx mori brain.
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.
Hossain
Monwar
M
Division of Life Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Japan.
Shimizu
Sakiko
S
Fujiwara
Haruhiko
H
Sakurai
Sho
S
Iwami
Masafumi
M
D000818:Animals; D012831:Bombyx / Q000254:growth & development / Q000502:physiology*; D001921:Brain / Q000166:cytology / Q000378:metabolism*; D004441:Ecdysterone / Q000494:pharmacology; D018507:Gene Expression Regulation, Developmental; D007301:Insect Hormones / Q000378:metabolism*; D008018:Life Cycle Stages; D020033:Protein Isoforms / Q000145:classification / Q000187:drug effects / Q000378:metabolism; D011987:Receptors, Steroid / Q000145:classification / Q000187:drug effects / Q000378:metabolism*; D015854:Up-Regulation
D007301:Insect Hormones; D020033:Protein Isoforms; D011987:Receptors, Steroid; C055469:ecdysone receptor; D004441:Ecdysterone; C009089:prothoracicotropic hormone