title: Recombinant E-peptides of pro-IGF-I have mitogenic activity.
abstract: In mammals, the post-translational proteolytic modification of many pro-hormones generates multiple peptides with similar or distinct biological activities. The production of mature insulin-like growth factor I (IGF-I) involves the cleavage of an E-peptide from pro-IGF-I. Although the IGF-I E-peptides are conserved among vertebrate species, their fate and biological roles have not been identified. To test whether the E-peptides possess any biological activity, three recombinant E-peptides of pro-IGF-I, namely Ea-2-, Ea-3- and Ea-4-peptides of rainbow trout, Oncorhynchus mykiss, were produced in vitro with a His-tag expression system and partially purified with an affinity Ni++ column. The mitogenic activity of each E-peptide was determined by (1) the stimulation of total DNA content increase as measured by a fluorometric method and/or (2) stimulation of [3H]-thymidine incorporation into DNA. Recombinant Ea-4-peptide elicited a dose-related increase in both mitogenic assays in NIH3T3 cells. To further test the specificity of the mitogenic activity of Ea-4-peptide, three other cell lines were used: retroviral transformed human embryonic kidney cells (293GP), human mammary gland tumor cells (MCF-7) and caprine mammary epithelial cells (CMEC). Similar levels of mitogenic activity were observed in all cell lines tested for Ea-4-peptide. Mitogenic activity was also observed with recombinant Ea-2- and Ea-3-peptides when assayed in NIH3T3 cells. These results suggest that E-peptides of rainbow trout pro-IGF-I possess mitogenic activity in heterologous systems.
authors.affiliation: Biotechnology Center and Department of Molecular and Cell Biology, University of Connecticut, Storrs 06269-3149, USA.
authors.forename: X C
authors.initials: XC
authors.lastname: Tian
authors.forename: M J
authors.initials: MJ
authors.lastname: Chen
authors.forename: A G
authors.initials: AG
authors.lastname: Pantschenko
authors.forename: T J
authors.initials: TJ
authors.lastname: Yang
authors.forename: T T
authors.initials: TT
authors.lastname: Chen
mesh_terms: D000818:Animals; D002460:Cell Line; D006041:Goats; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D008934:Mitogens / Q000494:pharmacology*; D017686:Oncorhynchus mykiss; D010446:Peptide Fragments / Q000494:pharmacology*; D011355:Prodrugs / Q000494:pharmacology*; D011498:Protein Precursors / Q000494:pharmacology*; D011994:Recombinant Proteins
chemical_list: D008934:Mitogens; D010446:Peptide Fragments; D011355:Prodrugs; D011498:Protein Precursors; D011994:Recombinant Proteins; C119953:pro-insulin-like growth factor I; D007334:Insulin-Like Growth Factor I