title: Characterization and identification of EGF-receptors as an integral component of membrane structure of human endometrial stromal cells in vitro.
abstract: The epidermal growth factor EGF is a well known mitogenic agent, elicits significant biological responses in intact animals, organs and cell cultures, and might be involved in the endometrial receptivity for successful embryo implantation. Although immunohistological and binding studies have detected EGF-binding activity in endometrial tissues, the nature of the EGF- binding site has not been fully investigated. Therefore, this study was performed to characterize and identify the nature of the endometrial stromal cell EGF-binding activity and to demonstrate EGF effects on stromal cell growth under in vitro conditions. Stimulation of cellular proliferation with EGF in various concentrations for 6 days revealed a significant increase of the proliferation rate up to 150% of that found in control subjects in a dose-dependent fashion, reaching a maximum stimulation at 10 nM EGF. Binding studies with labelled 125I-EGF confirmed the localization of the EGF-binding site in the membrane fraction of stromal cells. Furthermore, this binding activity was found to be a ligand-saturable molecular species with a dissociation constant of about 1.75 nM, and with a high specificity to EGF ligands. Affinity cross-linking studies revealed that the stromal cell membrane EGF-binding component is a protein molecule of 170,000 daltons, and has no subunit structure bound with disulphide bridges. The electrophoretic migration pattern of this molecule corresponds to EGF-receptor species already identified in other cells and tissues. This was further documented by specific reactivity with EGF-receptor antibodies and EGF/alpha-TGF peptides as well. In conclusion, the EGF-binding activity of stromal cell membranes has the nature and identity of EGF-receptor species, and is a functionally integral component of the stromal cell membrane structure.
authors.affiliation: Department of Obstetrics and Gynecology, Klinikum Grosshadern, Ludwig Maximilians University, Munich, Germany.
authors.forename: G A
authors.initials: GA
authors.lastname: Singer
authors.forename: T
authors.initials: T
authors.lastname: Strowitzki
mesh_terms: D001667:Binding, Competitive; D002455:Cell Division / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism*; D003432:Cross-Linking Reagents; D004717:Endometrium / Q000166:cytology*; D004815:Epidermal Growth Factor / Q000378:metabolism / Q000494:pharmacology*; D066246:ErbB Receptors / Q000378:metabolism*; D005260:Female; D006801:Humans; D007700:Kinetics; D017154:Stromal Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
chemical_list: D003432:Cross-Linking Reagents; D004815:Epidermal Growth Factor; D066246:ErbB Receptors