Differential regulation of gonadotropin receptors (fshr and lhcgr) by epidermal growth factor (EGF) in the zebrafish ovary
- Authors
- Liu, K.C., and Ge, W.
- ID
- ZDB-PUB-121016-4
- Date
- 2013
- Source
- General and comparative endocrinology 181: 288-294 (Journal)
- Registered Authors
- Ge, Wei
- Keywords
- egf, fshr, lhcgr, ovary, zebrafish
- MeSH Terms
-
- Animals
- Betacellulin
- Epidermal Growth Factor/pharmacology*
- Estradiol/pharmacology
- Female
- Heparin-binding EGF-like Growth Factor
- Intercellular Signaling Peptides and Proteins/pharmacology
- Ovarian Follicle/drug effects
- Ovarian Follicle/metabolism
- Ovary/metabolism*
- Receptors, Gonadotropin/genetics
- Receptors, Gonadotropin/metabolism*
- Zebrafish/genetics
- Zebrafish/metabolism*
- Zebrafish Proteins/genetics
- Zebrafish Proteins/metabolism*
- PubMed
- 23036736 Full text @ Gen. Comp. Endocrinol.
Epidermal growth factor (egf) is expressed in the zebrafish oocyte whereas its receptor EGF receptor (egfr) is expressed in the somatic follicle layer, strongly suggesting a role for Egf in the intrafollicular paracrine communication that mediates an oocyte-to-follicle cell signaling pathway. However, the exact function of Egf in the follicle remains largely unknown. The present study aimed to explore the possible role of Egf in regulating gonadotropin receptors (fshr and lhcgr) in cultured zebrafish follicle cells. EGF down-regulated lhcgr expression dose-dependently in a biphasic manner with significant effect observed at 1.5 and 24 h. The effect was mediated via Egfr on the follicle cells. On the contrary, EGF also tended to decrease fshr expression at 1.5 h but it appeared to up-regulate fshr at 24 h. The EGF suppression of lhcgr expression was functionally relevant as pre-exposure to EGF reduced the follicle cell responsiveness to LH/hCG. We have recently reported that estradiol (E2) strongly stimulated lhcgr expression in the zebrafish ovary. In the current study, we further demonstrated that EGF and other EGF family members, heparin-binding EGF-like growth factor (HBEGF), transforming growth factor α (TGFα) and betacellulin (BTC), all reduced basal and E2-induced lhcgr expression. This study provides evidence for a potential paracrine role of Egf and its related peptides in the zebrafish follicle. The oocyte-derived EGF family ligands may actively control the process of follicle growth and maturation by differentially controlling the expression of fshr and lhcgr in the follicle cells in a paracrine manner.