title: Insulin signaling is involved in hematopoietic regulation in an insect hematopoietic organ.
abstract: Only a few extracellular hematopoietic factors have been identified in insects. We previously developed an in vitro culture system for the larval hematopoietic organ (HPO) of the silkworm Bombyx mori, and found that cell proliferation is linked to hemocyte discharge from the HPO. In this study, we tested hematopoietic activity of bombyxin, a peptide in the insulin family. When silkworm HPO was cultured with synthetic bombyxin-II, the number of discharged hemocytes increased in a dose-dependent manner, indicating that bombyxin promoted cell proliferation in the HPO. However, a neutralization experiment using anti-bombyxin-II antibody revealed that bombyxin is not the primary effector in larval plasma. Similarly, bovine insulin showed hematopoietic activity. Addition of molting hormone, 20-hydroxyecdysone, circumstantially enhanced the hematopoietic activity of bombyxin and insulin. Bombyxin and insulin induced phosphorylation of different sets of proteins in the HPO, suggesting that their signaling pathways are different.
authors.affiliation: National Institute of Agrobiological Sciences, 1-2 Ohwashi, Tsukuba, Ibaraki 305-8634, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Nakahara
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Matsumoto
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Kanamori
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kataoka
authors.forename: Akira
authors.initials: A
authors.lastname: Mizoguchi
authors.forename: Makoto
authors.initials: M
authors.lastname: Kiuchi
authors.forename: Manabu
authors.initials: M
authors.lastname: Kamimura
mesh_terms: D000818:Animals; D012831:Bombyx / Q000502:physiology*; D002417:Cattle; D004441:Ecdysterone / Q000494:pharmacology; D006410:Hematopoiesis / Q000187:drug effects / Q000502:physiology*; D006434:Hemocytes / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology*; D007814:Larva / Q000502:physiology; D009479:Neuropeptides / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects
chemical_list: D007328:Insulin; D009479:Neuropeptides; C077536:bombyxin II; D004441:Ecdysterone