title: Modulatory effects of bombyxin on ecdysteroidogenesis in Bombyx mori prothoracic glands.
abstract: In the present study, we investigated the modulatory effects of ecdysteroidogenesis of prothoracic glands (PGs) by bombyxin, an endogenous insulin-like peptide in the silkworm, Bombyx mori. The results showed that bombyxin stimulated ecdysteroidogenesis during a long-term incubation period and in a dose-dependent manner. Moreover, the injection of bombyxin into day 4-last instar larvae increased ecdysteroidogenesis 24h after the injection, indicating its possible in vivo function. Phosphorylation of the insulin receptor and Akt, and the target of rapamycin (TOR) signaling were stimulated by bombyxin, and stimulation of Akt phosphorylation and TOR signaling appeared to be dependent on phosphatidylinositol 3-kinase (PI3K). Bombyxin inhibited the phosphorylation of adenosine 5'-monophosphate-activated protein kinase (AMPK), and the inhibition appeared to be PI3K-independent. Bombyxin-stimulated ecdysteroidogenesis was blocked by either an inhibitor of PI3K (LY294002) or a chemical activator of AMPK (5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside, AICAR), indicating involvement of the PI3K/Akt and AMPK signaling pathway. Bombyxin did not stimulate extracellular signal-regulated kinase (ERK) signaling of PGs. Bombyxin, but not prothoracicotropic hormone (PTTH) stimulated cell viability of PGs. In addition, bombyxin treatment also affected mRNA expression levels of insulin receptor, Akt, AMPKα, -β, and -γ in time-dependent manners. These results suggest that bombyxin modulates ecdysteroidogenesis in B. mori PGs during development.
authors.affiliation: Department of Biology, National Museum of Natural Science,1 Kuan-Chien Road, Taichung 404-19, Taiwan, ROC. Electronic address: gu330@mail.nmns.edu.tw.
authors.forename: Shi-Hong
authors.initials: SH
authors.lastname: Gu
authors.affiliation: Chung Hwa University of Medical Technology, 89 Wen-Hwa 1st Road, Jen-Te Township, Tainan County 717, Taiwan, ROC.
authors.forename: Chien-Hung
authors.initials: CH
authors.lastname: Chen
authors.affiliation: Department of Biology, National Museum of Natural Science,1 Kuan-Chien Road, Taichung 404-19, Taiwan, ROC.
authors.forename: Yun-Chin
authors.initials: YC
authors.lastname: Hsieh
authors.affiliation: Department of Biology, National Museum of Natural Science,1 Kuan-Chien Road, Taichung 404-19, Taiwan, ROC.
authors.forename: Pei-Ling
authors.initials: PL
authors.lastname: Lin
authors.affiliation: Department of Biology, National Museum of Natural Science,1 Kuan-Chien Road, Taichung 404-19, Taiwan, ROC.
authors.forename: Shun-Chieh
authors.initials: SC
authors.lastname: Young
mesh_terms: D000620:Aminoimidazole Carboxamide / Q000819:agonists / Q000031:analogs & derivatives; D000818:Animals; D012831:Bombyx / Q000254:growth & development / Q000378:metabolism*; D002867:Chromones / Q000494:pharmacology; D026461:Ecdysteroids / Q000096:biosynthesis*; D004702:Endocrine Glands / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D007301:Insect Hormones / Q000096:biosynthesis; D019476:Insect Proteins / Q000378:metabolism; D007814:Larva / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D009479:Neuropeptides / Q000494:pharmacology*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D012265:Ribonucleotides / Q000819:agonists; D015398:Signal Transduction
chemical_list: D002867:Chromones; D026461:Ecdysteroids; D007301:Insect Hormones; D019476:Insect Proteins; D009025:Morpholines; D009479:Neuropeptides; D000081082:Phosphoinositide-3 Kinase Inhibitors; D012265:Ribonucleotides; C075028:bombyxins; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D000620:Aminoimidazole Carboxamide; C009089:prothoracicotropic hormone; D048049:Extracellular Signal-Regulated MAP Kinases; C031143:AICA ribonucleotide
keywords: Bombyx mori; Bombyxin; Ecdysone; Insulin; Prothoracic glands; Signal transduction