Insulin-like growth factor-1 (IGF-1) specifically binds to bovine lens epithelial cells and increases the number of fibronectin receptor sites.
The purpose of the study was to determine the quantitative characteristics of IGF-1 binding sites in lens cells and to investigate its ability to modulate cell growth, in particular by inducing integrin expression. Studies were carried out in bovine lens epithelial cells in culture. IGF-1 receptor binding parameters were measured from saturation experiments with 125I-IGF-1. Scatchard plot indicates one class of high affinity sites (Kd = 2.5 +/- 1.5 nM). In addition, we showed that this growth factor was synthesized and released by lens cells. The characteristics of the receptor sites are in accordance with the effects of the growth factor (e.g. stimulation of DNA synthesis) in the range of nM concentrations. Moreover, by incubating cells with IGF-1 (12 nM) for 40 hr we demonstrated that the expression of integrin, the fibronectin receptor, was activated (N = 885 +/- 169 x 10(3) sites/cell vs N = 453 +/- 105 x 10(3) sites/cell in control cultures) without modification of its affinity (Kd congruent to 16 x 10(-8) M). These new data emphasize the role of IGF-1 in the regulation of migration, proliferation and differentiation of mature lens cells.
Palmade
F
F
Laboratoire de Physiologie Cellulaire, Université Montpellier I, France.
Sechoy-Chambon
O
O
Coquelet
C
C
Bonne
C
C
D000818:Animals; D002417:Cattle; D002454:Cell Differentiation; D002455:Cell Division; D002465:Cell Movement; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D004848:Epithelium / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000378:metabolism* / Q000494:pharmacology; D007908:Lens, Crystalline / Q000187:drug effects / Q000378:metabolism*; D017526:Receptor, IGF Type 1 / Q000378:metabolism; D017469:Receptors, Fibronectin / Q000378:metabolism*; D013936:Thymidine / Q000378:metabolism
D005353:Fibronectins; D017469:Receptors, Fibronectin; D007334:Insulin-Like Growth Factor I; D004247:DNA; D017526:Receptor, IGF Type 1; D013936:Thymidine