Binding properties and proliferative potency of insulin-like growth factor I in fetal mouse liver cells.
Specific high-affinity receptor(s) for insulin-like growth factor I have been identified in fetal mouse liver cells (FMLC) rich in late erythroid progenitors (CFU-E). Competition for [125I]IGF-I binding by IGFs and insulin demonstrated the presence of Type-I IGF receptors. Scatchard analysis of the binding data revealed a single class of receptors (Kd, 1.2 nM; R0, 600 sites per cell). Erythroid colony formation and DNA synthesis by these cells were enhanced by IGF-I alone or in combination with erythropoietin (Epo). Subfractionations of FMLC using Percoll density gradients showed that a significant part of [125I]IGF-I binding was observed in the CFU-E-enriched fraction and that the erythroid colony formation was mostly enhanced by IGF-I in the same fraction. IGF-I stimulated the phosphorylation of the beta-subunit of the Type-I receptors. These results indicate that IGF-I modulates the Epo-stimulated proliferation and differentiation of erythroid progenitors via its specific receptors.
D000818:Animals; D002455:Cell Division / Q000187:drug effects; D005333:Fetus / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000493:pharmacokinetics* / Q000494:pharmacology; D008099:Liver / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D051379:Mice / Q000196:embryology* / Q000378:metabolism; D008813:Mice, Inbred ICR; D010766:Phosphorylation; D011972:Receptor, Insulin / Q000378:metabolism; D017451:Receptors, Somatomedin; D013002:Somatomedins / Q000493:pharmacokinetics*
D017451:Receptors, Somatomedin; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D011972:Receptor, Insulin