Activity of insulin growth factors and shrimp neurosecretory organ extracts on a lepidopteran cell line

Abstract

Ecdysteroids, or molting hormones, have been proven to be key differentiation regulators for epidermal cells in the postembryonic development of arthropods. Regulators of cell proliferation, 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 preliminary characterization of potential growth factors in arthropods by adapting the procedures designed to detect such factors in vertebrates to an insect cell line (IAL‐PID2) established from imaginal discs of the Indian meal moth. We verified the ability of these tests to measure the proliferation of IAL‐PID2 cells. We tested mammalian insulin and insulin‐like growth factors (IGF‐I, IGF‐II). Following an arrest of cell proliferation by serum deprivation, 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‐PID2 cells. The cell line was then used in a test for functional characterization 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. © 1997 Wiley‐Liss, Inc.

Rhythmic autocrine activity in cultured insect epidermal cells

“…When IAL-PID2 cells were synchronized under experimental conditions described previously (Hatt et al, 1997), a periodic production of ecdysteroids was observed over 36 h corresponding roughly to the doubling time of the cell population. Two maxima were observed 4 and 32 h after cell cycle resumption following the arrest in G1 caused by serum deprivation.…”

“…In the other half, used as controls, FBS-supplemented medium was added. As already demonstrated (Hatt et al, 1997), growth of the cell population gradually ceased from 16 to 48 h following serum deprivation, whereas cell number almost doubled during the same period of time in controls (Fig 3A).…”

“…The cells ceased to proliferate and accumulated prior to entry into S phase. Addition of FBS allowed the cells to reenter the cell cycle with good synchrony (Hatt et al, 1994(Hatt et al, , 1997.…”

Synchronization of Plodia interpunctella lepidopteran cells and effects of 20‐hydroxyecdysone

“…A protocol of cell synchronization by serum deprivation has been established from the IAL‐PID2 cell line derived from imaginal discs of the Indian meal moth Plodia interpunctella (Lynn & Oberlander, 1983) and used in conjunction with studies on 20E action. Serum deprivation brought IAL‐PID2 cells to a quiescence phase in which most of cells were in the G0/G1 stage (Hatt et al ., 1997). The addition of fetal bovine serum (FBS) triggered cell cycle resumption and a majority of cells were recovered in S phase after an 8 h period following FBS supplement.…”

“…The addition of fetal bovine serum (FBS) triggered cell cycle resumption and a majority of cells were recovered in S phase after an 8 h period following FBS supplement. Nevertheless, this synchrony was short lived and several separate peaks of labelled mitotic cells could be detected (Hatt et al ., 1997; Auzoux‐Bordenave et al ., 2002). However, under these conditions of synchronization, a period of cell sensitivity to 20E was determined at the beginning of G2/M phase in correlation with the antiproliferative effect of 20E (Auzoux‐Bordenave et al ., 2002).…”