Nongenomic action of an insect steroid hormone in steroid-induced programmed cell death.
Programmed cell death (PCD) of the silkworm silk glands is triggered by the insect steroid hormone, 20-hydroxyecdysone (20E), and proceeds sequentially through cell shrinkage, nuclear condensation, DNA fragmentation, nuclear fragmentation and apoptotic body formation. A protein synthesis inhibitor, cycloheximide (CHX, 2 mM) induced a cell death that exhibited only nuclear and DNA fragmentation. A concentration of 0.2 mM CHX was ineffective at inducing the cell death when added alone, but in the presence of 20E, a cell death similar to that induced by 2 mM CHX was resulted with accompanying nuclear condensation. Since 2 and 0.2 mM CHX inhibited protein synthesis equally, the DNA and nuclear fragmentation appear to be mediated by a nongenomic action of 20E. In addition, we show a possible involvement of Ca2+-PKC-caspase-3 like protease pathway in the nongenomic action. The data suggest that 20E-induced PCD is accomplished through the integration of genomic and nongenomic actions.
Iga
Masatoshi
M
Division of Life Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakumamachi, Kanazawa 920-1192, Japan. iga@stu.kanazawa-u.ac.jp
Iwami
Masafumi
M
Sakurai
Sho
S
D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D012831:Bombyx; D002118:Calcium / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D061945:Caspase Inhibitors; D002478:Cells, Cultured / Q000166:cytology / Q000187:drug effects; D003513:Cycloheximide / Q000494:pharmacology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004441:Ecdysterone / Q000494:pharmacology*; D007814:Larva / Q000166:cytology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism
D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D004441:Ecdysterone; D004247:DNA; D003513:Cycloheximide; D011493:Protein Kinase C; D053148:Caspase 3; D002118:Calcium