Activity of Insulin Growth Factors and Shrimp Neurosecretory Organ Extracts on a Lepidopteran Cell Line

摘要

Ecdysteroids, or molting hormones, have been proven to be key differentiation regulators for epidermal cells in the postem- bryonic development of arthropods. Regulators of cell prolifera- tion, however, remain largely unknown. To date, no diffusible insect peptidic growth factors have been characterized. Molecules structurally related to insulin have been discovered in insects, as in other eucaryotes. We developed in vitro tests for the pre- liminary characterization of potential growth factors in arthro- pods by adapting the procedures designed to detect such factors in vertebrates to an insect cell line (IAL-pm2) established from imaginal discs of the Indian meal moth. We verified the ability of these tests to measure the proliferation of IAL-pm2 cells. We tested mammalian insulin and insulin-like growth factors (IGF-I, IGF-II). Following an arrest of cell proliferation by serum depri- vation, IGF-I and IGF-II caused partial resumption of the cell cycle, evidenced by DNA synthesis. In contrast, the addition of 20-hydroxyecdysone arrested the proliferation of the IAL-pm2 cells. The cell line was then used in a test for functional charac- terization of potential growth factors originating from the penaeid shrimp, Penaeus vannamei. Crude extracts of neurosecretory and nervous tissues, eyestalks, and ventral neural chain compensated for serum deprivation and stimulated completion of mitosis. Arch. Insect Biochem. Physiol. 34:313-328, 1997.