Purchase this article with an account.
Danielle M. Robertson, Meifang Zhu, H D. Cavanagh; Nuclear Localization of IGFBP3 and IGF-1R in Proliferating Corneal Epithelial Cells. Invest. Ophthalmol. Vis. Sci. 2011;52(14):308.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Insulin-like growth factor binding protein-3 (IGFBP3) has known roles in proliferation, cell migration and apoptosis, which are tissue and cell type specific. In the human corneal epithelium, IGFBP3 is differentially localized throughout the limbal and corneal epithelium. The purpose of this study is to characterize the subcellular localization of IGFBP3 and members of the insulin-like growth factor (IGF) system, IGF1 and IGF-1R, in cultured human corneal epithelial cells.
Human telomerized corneal epithelial cells (hTCEpi) were cultured in KGM-2 serum-free media. For localization studies, hTCEpi cells were seeded on glass coverslips and grown overnight or cultured on collagen-coated inserts in the presence of 1.15mM calcium. Localization of IGFBP3, IGF1, and the IGF-1R was determined by immunofluorescence. Nuclei were counter-stained using DRAQ5. Cells were imaged using laser scanning confocal microscopy. Localization of IGF-1R and IGFBP3 was confirmed by subcellular fractionation and western blot.
In subconfluent hTCEpi cells, IGFBP3 localized to the endoplasmic reticulum, nuclear membrane and nucleus. IGFBP3 expression was altered in cells undergoing mitosis. Triple-labeling experiments demonstrated co-localization of IGFBP3 with IGF1 and IGF-1R in the nucleus. Nuclear localized IGF-1R staining was weak to absent in hTCEpi cells following growth on collagen-coated inserts in the presence of increased calcium. In areas of multi-layering, IGF-1R localized to the plasma membrane in superficial cells. Subcellular fractionation confirmed the expression of IGFBP3 and IGF-1R in specific cellular compartments. Both IGFBP3 and IGF-1R were identified bound to nuclear chromatin.
IGFBP3 is expressed by proliferating corneal epithelial cells. The chromatin-bound nuclear co-localization suggests a role for IGFBP3 and IGF-1R in mediating proliferative events in the corneal epithelium.
This PDF is available to Subscribers Only