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Ultraviolet-B (290-320 nm)-irradiation inhibits epidermal growth-factor binding to mammalian cells
M S Matsui1, L Laufer, S Scheide
1Department of Dermatology, Columbia University, New York, New York 10032.
Abstract:
Mitogens, such as polypeptide growth factors and phorbol ester tumor promoters, act by binding to specific receptors and inducing a pleiotropic response in cultured mammalian cells, which results in the induction of cellular proliferation. An early effect of such agents is the inhibition of binding of epidermal growth factor (EGF) to its receptor. Ultraviolet radiation has also been shown to induce a proliferative response in vivo and in vitro and to act as a tumor promoter in animal skin. We, therefore, examined the effect of ultraviolet radiation (UVB - 290-320 nm) on EGF binding to cells in culture. We found that UVB (100-300 J/m2) induced a rapid, dose-dependent inhibition of EGF binding in a mouse fibroblast cell line, which resulted from a decrease in both number and affinity of binding sites. Phosphorylation of the EGF receptor by protein kinase C (PKC) is not likely to be the mechanism for inhibition, since UVB treatment did not result in PKC activation or modulation of phorbol diester binding.
Insights
Ultraviolet B (UVB) radiation rapidly inhibits epidermal growth factor (EGF) binding to its receptor in mouse cells. This effect stems from reduced binding site number and affinity, not protein kinase C activation.
Area of Science:
- Cell Biology
- Molecular Biology
- Dermatology
Background:
- Mitogens like growth factors stimulate cell proliferation by binding to specific receptors.
- Epidermal growth factor (EGF) receptor binding is an early target for mitogenic agents.
- Ultraviolet radiation (UVB) is known to promote cell proliferation and tumor development.
Purpose of the Study:
- To investigate the impact of UVB radiation on EGF binding to its receptor in cultured cells.
- To determine the mechanism behind UVB-induced alterations in EGF receptor interaction.
Main Methods:
- Exposure of a mouse fibroblast cell line to varying doses of UVB radiation (100-300 J/m2).
- Measurement of EGF binding to its receptor before and after UVB exposure.
- Assessment of protein kinase C (PKC) activation and phorbol diester binding following UVB treatment.
Main Results:
- UVB radiation caused a rapid, dose-dependent inhibition of EGF binding.
- The inhibition of EGF binding was attributed to a decrease in both the number and affinity of EGF receptors.
- UVB exposure did not activate PKC or alter phorbol diester binding, suggesting PKC is not involved.
Conclusions:
- UVB radiation significantly impairs EGF receptor function in mouse fibroblasts.
- The mechanism of inhibition involves changes in receptor quantity and binding characteristics, independent of PKC signaling.
- These findings highlight a novel pathway through which UVB may influence cellular processes like proliferation and tumor promotion.