MbIDGF,a novel member of the imaginal disc growth factor family in Mamestra brassicae,stimulates cell proliferation in two lepidopteran cell lines without insulin

摘要

Imaginal disc growth factor (IDGF) is a soluble polypeptide growth factor that was first identified from the conditioned medium of Drosophilia imaginal disc C1.8+ cells.Working with insulin,IDGF stimulated the growth of cultured imaginal disk cells,which suggested that IDGF might function as a cofactor of Drosophila insulin or insulin like peptide.Here we report a new member of the IDGF family,named MbIDGF,from the cabbage armyworm,Mamestra brassicae.Using a cloned cDNA of MbIDGF,recombinant MbIDGF protein was expressed in baculovirus-infected Sf9 cells and purified.Without insulin,the recombinant MbIDGF protein stimulated cell growth of SES-MaBr-4 and NIAS-MaBr-93 cell lines that were derived from the fat bodies and hemocytes of M.brassicae,in a dose-dependent manner.The saturation of growth stimulation by MbIDGF was attained for the two types of cells at 80ng/ml (0.8nM) and 300ng/ml (6nM),respectively.The results suggest that MbIDGF may stimulate the growth of lepidopteran cells by a new mechanism without associating with the insulin pathway.