Epidermal growth factor receptor binding and biological activity in the ovary of goldfish, Carassius auratus.
The receptor binding and biological activity of epidermal growth factor-urogastrone (EGF) was characterized in the follicle-enclosed goldfish oocyte. The binding of 125I-labeled mouse EGF (mEGF) to goldfish ovarian membrane preparation was peptide specific, saturable, reversible, and dependent on time and tissue concentration. Binding data analysis indicated the presence of a single class of high-affinity binding sites with an estimated equilibrium dissociation constant of 4.4 +/- 1.8 x 10(-10) M. The 125I-mEGF binding was displaced by unlabeled mEGF and by human recombinant transforming growth factor-alpha (hTGF-alpha). Both mEGF and hTGF-alpha were found to stimulate reinitiation of oocyte meiosis, as indicated by germinal vesicle breakdown (GVBD). Treatment with mEGF and hTGF-alpha stimulated GVBD from a basal level of 8.5 to approximately 30% with an estimated half-maximal effective dose for EGF of 5.80 +/- 0.82 + 10(-10) and for hTGF-alpha, 1.9 +/- 1.0 x 10(-10) M. Furthermore, treatment with mEGF marginally increased 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one (DHP)-induced GVBD without significantly influencing the gonadotropin-induced response. Treatment with either mEGF or hTGF-alpha significantly reduced human chorionic gonadotropin-stimulated testosterone production in a concentration-related manner. These data suggest that members of the EGF family may play a role in the regulation of ovarian function in goldfish.
Pati
D
D
Department of Biological Sciences, University of Calgary, Alberta Canada.
Balshaw
K
K
Grinwich
D L
DL
Hollenberg
M D
MD
Habibi
H R
HR
D000818:Animals; D001667:Binding, Competitive; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000378:metabolism / Q000502:physiology*; D005260:Female; D006054:Goldfish / Q000378:metabolism*; D006062:Gonadotropins / Q000494:pharmacology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006908:Hydroxyprogesterones / Q000494:pharmacology; D008540:Meiosis / Q000187:drug effects; D051379:Mice; D009865:Oocytes / Q000378:metabolism; D009994:Osmolar Concentration; D006080:Ovarian Follicle / Q000378:metabolism; D010053:Ovary / Q000166:cytology / Q000378:metabolism*; D013739:Testosterone / Q000096:biosynthesis; D016211:Transforming Growth Factor alpha / Q000494:pharmacology
D006062:Gonadotropins; D006908:Hydroxyprogesterones; D016211:Transforming Growth Factor alpha; C021012:17 alpha,20 beta-dihydroxypregn-4-en-3-one; D013739:Testosterone; D004815:Epidermal Growth Factor; D066246:ErbB Receptors