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Characterization of binding and receptors for epidermal growth factor in smooth muscle
L B Nanney1, C M Stoscheck, L E King
1Department of Plastic Surgery, Vanderbilt University, Nashville, Tennessee.
Abstract:
The mitogenic and differentiation-inducing activities of epidermal growth factor (EGF) in epithelial tissues have been well described. Since non-mitogenic effects of EGF, especially in mesenchymal tissues such as smooth muscle are not well-known (Nanney et al. 1984), we have examined EGF-binding and receptors in smooth muscle from many sites. Specific EGF binding sites were detected by incubating small pieces of tissue with 125I-EGF; immunoreactive EGF receptors were detected by immunohistochemistry. In-situ localization of 125I-EGF binding sites and immunoreactive EGF receptors of smooth muscle cells in intact mammalian tissues were identical using either 125I-EGF autoradiography or anti-EGF receptor antibody in an immunoperoxidase method. Cultured rat aortic smooth muscle also contained specific EGF receptors as detected by their biological response to EGF-binding and internalization of 125I-EGF, as well as EGF-stimulated phosphorylation of a 170K protein. The presence of EGF receptors in a well-differentiated smooth muscle cell indicates that EGF may play a physiological, but non-mitogenic role in mammalian tissues in vivo.
Insights
Epidermal growth factor (EGF) receptors are present in mammalian smooth muscle. This suggests EGF plays a physiological, non-mitogenic role in these tissues, distinct from its effects on epithelial cells.
Area of Science:
- Cell biology
- Molecular biology
- Physiology
Background:
- Epidermal growth factor (EGF) is known for its mitogenic and differentiation-inducing effects in epithelial tissues.
- The non-mitogenic roles of EGF in mesenchymal tissues, like smooth muscle, are less understood.
Purpose of the Study:
- To investigate the presence and localization of EGF binding sites and receptors in mammalian smooth muscle.
- To determine if EGF has a functional role in smooth muscle cells.
Main Methods:
- Incubation of smooth muscle tissue with 125I-EGF to detect specific binding sites.
- Immunohistochemistry using anti-EGF receptor antibody to detect immunoreactive EGF receptors.
- Analysis of cultured rat aortic smooth muscle for EGF receptor-mediated biological responses.
Main Results:
- Specific EGF binding sites and EGF receptors were identified in smooth muscle from various mammalian sites.
- In situ localization of EGF binding and receptors in smooth muscle cells was consistent using autoradiography and immunohistochemistry.
- Cultured smooth muscle cells demonstrated EGF receptor presence through EGF binding, internalization, and stimulated protein phosphorylation.
Conclusions:
- Mammalian smooth muscle cells possess specific EGF receptors.
- EGF likely plays a physiological, non-mitogenic role in mammalian smooth muscle tissues in vivo.