Elsevier

Experimental Eye Research

Volume 63, Issue 6, December 1996, Pages 621-629
Experimental Eye Research

Regular article
IGF Enhancement of FGF-induced Fibre Differentiation and DNA Synthesis in Lens Explants

https://doi.org/10.1006/exer.1996.0156Get rights and content

Abstract

The aim of this study was to carry out an analysis of the effects of insulin-like growth factors (IGFs) on responses induced by FGF in lens epithelial explants. Central explants from postnatal rats were cultured with concentrations of FGF-2 known to stimulate fibre differentiation or cell proliferation, with and without IGF-I or IGF-II at concentrations ranging from 0–1000 ng ml−1. Fibre-specific β- and γ-crystallin accumulation was determined by ELISA after 5–10 days culture and [3H]thymidine incorporation was assessed at 18–24 hr. Generally, both FGF and IGF were added on day 0. In the absence of FGF, IGF induced significant DNA synthesis, but negligible fibre differentiation. When included with FGF, however, IGF synergistically enhanced both DNA synthesis and the accumulation of fibre-specific crystallins. For β-crystallin, it was shown that this enhancement reflected a substantial increase in the amount of crystallin in individual cells, not merely an increase in cell numbers. The potentiating effects of IGF-I and IGF-II were comparable. For the fibre differentiation response, it was shown that the cells remained responsive to the synergistic influence of IGF-1 for up to 4 days of culture. The dose response characteristics of the fibre differentiation response suggest that mediation occurs mainly through the IGF-I receptor. Because IGF, as well as FGF, is known to be present in the ocular media, IGF may have a role in modulating FGF-induced responses in the lens in vivo.

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For correspondence at: Department of Anatomy and Histology, University of Sydney, Sydney, NSW, Australia 2006.

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