title: Spatiotemporal expression analysis of nuclear estrogen receptors in the zebrafish ovary and their regulation in vitro by endocrine hormones and paracrine factors.
abstract: Estradiol (E2) stimulates luteinizing hormone receptor (lhcgr) expression via nuclear estrogen receptors (nERs) in the zebrafish ovary. We have demonstrated that endocrine hormones such as gonadotropin (hCG) and paracrine factors such as epidermal growth factor (EGF) and pituitary adenylate cyclase-activating peptide (PACAP) can modulate E2-induced lhcgr expression in vitro. These observations raised a question on whether these hormones and factors exert their effects via regulating the expression of nERs. In this study, we first characterized the spatiotemporal expression profiles of three nER subtypes in the zebrafish ovary, including esr1 (ERα), esr2a (ERβ2) and esr2b (ERβ1). All three nERs increased their expression at the pre-vitellogenic stage and peaked at mid- (esr1 and esr2a) or late vitellogenic (esr2b) stage, followed by a significant decline at the full-grown stage. RT-PCR analysis showed that esr1 and esr2b were exclusively expressed in the follicle layer while esr2a was expressed in both compartments. We then examined how E2, hCG, PACAP and EGF regulated the expression of nERs in cultured zebrafish follicle cells. E2 quickly increased esr1 but reduced esr2a and esr2b expression from 1.5 to 12h of treatment. Similarly, EGF down-regulated esr2a significantly at 1.5h and this effect was further intensified at 24h. hCG decreased the expression of all three nER subtypes with similar potency throughout the 24-h time-course. Interestingly, PACAP exerted a biphasic regulation on esr2a. Our present study suggests that nERs, especially esr2a, provide potential target points for other hormones and factors to modulate E2 activity during folliculogenesis in the zebrafish.
authors.affiliation: School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Ka-Cheuk
authors.initials: KC
authors.lastname: Liu
authors.affiliation: School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Shuk-Wa
authors.initials: SW
authors.lastname: Lau
authors.affiliation: Centre of Reproduction, Development and Aging (CRDA), Faculty of Health Sciences, University of Macau, Taipa, Macau, China; School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China. Electronic address: weige@umac.mo.
authors.forename: Wei
authors.initials: W
authors.lastname: Ge
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D004703:Endocrine System / Q000187:drug effects / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology*; D047628:Estrogen Receptor alpha / Q000235:genetics*; D047629:Estrogen Receptor beta / Q000235:genetics*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects*; D006062:Gonadotropins / Q000494:pharmacology; D018377:Neurotransmitter Agents / Q000494:pharmacology; D006080:Ovarian Follicle / Q000187:drug effects / Q000378:metabolism; D010053:Ovary / Q000187:drug effects / Q000378:metabolism*; D019899:Paracrine Communication; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D011974:Receptors, LH / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D015027:Zebrafish / Q000254:growth & development / Q000378:metabolism; D029961:Zebrafish Proteins / Q000235:genetics
chemical_list: D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D006062:Gonadotropins; D018377:Neurotransmitter Agents; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D012333:RNA, Messenger; D011974:Receptors, LH; D029961:Zebrafish Proteins; D004958:Estradiol; D004815:Epidermal Growth Factor
keywords: Esr1; Esr2a; Esr2b; Estrogen receptors; Ovary; Zebrafish