IGF-I stimulates chemotaxis of human neuroblasts. Involvement of type 1 IGF receptor, IGF binding proteins, phosphatidylinositol-3 kinase pathway and plasmin system.
SH-SY5Y human neuroblastoma cells express IGF receptors, IGFs and IGF binding proteins (IGFBPs), and provide a model for studying the role of the IGF system in human neuronal development. We investigated the effect of IGF-I and des(1-3)IGF-I on the motility of SH-SY5Y cells by a cell migration assay based on the assessment of the number of cells which migrated across 8 microm pore size membranes and around an agarose drop. IGF-I and des(1-3)IGF-I stimulated neuroblast chemotaxis in a dose-dependent manner. Treatment of cells with these agents for 24 h resulted in a significant increase (IGF-I by 70% and des(1-3)IGF-I by 90%; P<0. 0001) in cell motility relative to control conditions. Addition of monoclonal antibody against type 1 IGF receptor (alpha-IR3), significantly (P<0.05) reduced the cell motility induced by IGF-I (by 30%) and des(1-3)IGF-I (by 70%). Wortmannin, a specific inhibitor of phosphatidylinositol (PI)-3 kinase intracellular signalling, also reduced the IGF-stimulated cell migration (by over 40%, P<0.01), indicating a key role of the PI-3 kinase pathway in mediating the IGF effect on neuroblast migration. Finally, cell treatment with plasminogen (PLG) markedly enhanced neuroblast migration (by over 200%, P<0.01), whereas incubation with the PLG inhibitor 4-(2-aminoethyl)-benzenesulphonyl fluoride reduced cell motility (by 80%, P<0.01), thus suggesting an involvement of PLG-dependent IGFBP proteolysis in the regulation of neuroblast motility. In conclusion, IGF-I is a potent stimulator of neuroblast migration through the activation of type 1 IGF receptor and the PI-3 kinase intracellular pathway. IGFBPs and the plasmin system seem to play a role in cell motility, although the nature and the extent of their involvement has yet to be elucidated.
Puglianiello
A
A
Laboratory of Paediatric Endocrinology, 'Tor Vergata' University, 00133-Rome, Italy.
Germani
D
D
Rossi
P
P
Cianfarani
S
S
D000911:Antibodies, Monoclonal; D002478:Cells, Cultured; D002633:Chemotaxis / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins / Q000502:physiology; D007334:Insulin-Like Growth Factor I / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010958:Plasminogen / Q000502:physiology; D015849:Plasminogen Inactivators / Q000502:physiology; D017526:Receptor, IGF Type 1 / Q000037:antagonists & inhibitors / Q000502:physiology
D000911:Antibodies, Monoclonal; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010958:Plasminogen; D015849:Plasminogen Inactivators; D017526:Receptor, IGF Type 1