Characterization of insulin-like growth factor-1 receptors in rabbit corneal epithelial cells.
Substance P (SP) and insulin-like growth factor-1 (IGF-1) synergistically facilitate corneal epithelial wound healing in vitro and in vivo. This synergism is mediated through the NK-1 receptors for SP, and IGF-1 does not modulate the binding affinity of NK-1 receptors. To clarify the effect of SP on the binding characteristics of IGF-1 receptors, the binding affinity and number of binding sites for IGF-1 in rabbit corneal epithelial cells were studied using a binding assay for(125)I-IGF-1. The binding affinity and number of binding sites for IGF-1 were determined by Scatchard plot analysis. Cultured rabbit corneal epithelial cells bound specifically to IGF-1. For IGF-1 in corneal epithelial cells, the binding affinity was 4 n m and the number of binding sites was 1x10(5)binding sites cell(-1). Although IGF-2 and insulin also bind to IGF-1 receptors, their affinities were, respectively, eight- and 300-fold lower than that of IGF-1. IGF-1 and IGF-2 stimulated corneal epithelial migration in the presence of SP, but insulin did not. Pretreatment of the corneal epithelial cells with SP (2x10(-5)m) failed to change the binding affinity or number of binding sites for IGF-1. These results demonstrated that corneal epithelial cells possess specific receptors for IGF-1. The synergistic effect of SP and IGF-1 on corneal epithelial wound healing does not result from regulation at the receptor level.
Nakamura
M
M
Department of Ophthalmology, Yamaguchi University School of Medicine, Ube City, Yamaguchi, Japan.
Chikama
T I
TI
Nishida
T
T
D000818:Animals; D001665:Binding Sites; D002478:Cells, Cultured; D004847:Epithelial Cells; D019573:Epithelium, Corneal / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D011817:Rabbits; D017526:Receptor, IGF Type 1 / Q000378:metabolism*; D013373:Substance P / Q000378:metabolism
D013373:Substance P; D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1