title: Evidence for the synthesis of a somatomedin similar to insulin-like growth factor I by chick embryo liver cells.
abstract: Chick embryo liver cells were incubated in serum-free and hormone-free medium and shown to produce a mitogen starting after the first day in culture. This mitogen was purified by gel filtration and ion-exchange chromatography and identified by several assay systems as a somatomedin similar to human insulin-like growth factor I (IGF-I). This somatomedin stimulates thymidine incorporation into DNA of chick fibroblasts, it reacts in an IGF-specific protein binding assay and it cross-reacts immunologically with antibodies prepared against human IGF-I, but not with those against IGF-II. Its behaviour on ion-exchange chromatography and on sodium dodecylsulfate/polyacrylamide gel electrophoresis is indistinguishable from that of authentic human IGF-I. Concomitantly with the mitogenic activity, chick liver cells produce IGF-binding protein. Addition of purified human IGF-I to the liver cells inhibits production of the binding protein. Chick liver cells may thus be used to study synthesis and regulation of IGF and its binding protein.
mesh_terms: D000818:Animals; D001681:Biological Assay; D002478:Cells, Cultured; D002642:Chick Embryo; D007328:Insulin; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D008934:Mitogens; D010455:Peptides; D011863:Radioimmunoassay; D011869:Radioligand Assay; D013002:Somatomedins / Q000096:biosynthesis*; D013936:Thymidine / Q000378:metabolism
chemical_list: D007328:Insulin; D008934:Mitogens; D010455:Peptides; D013002:Somatomedins; D013936:Thymidine