title: Transcriptional regulation of the epiregulin gene in the rat ovary.
abstract: Ovarian follicular development is initiated by FSH secreted from the pituitary gland. The FSH-induced follicular development involves granulosa cell proliferation and differentiation. We demonstrated that a growth factor of epidermal growth factor (EGF) family epiregulin was rapidly induced in the primary culture of rat ovarian granulosa cells by FSH within 1 h. Epiregulin gene expression was also observed in granulosa cells of antral ovarian follicles from pregnant mare's serum gonadotropin-primed rats in vivo. To analyze the regulation of gene expression of epiregulin, we isolated and characterized the rat epiregulin gene of 22.1 kb, including 3.8 kb of 5'-upstream region as well as all five exons and four introns. We determined the transcriptional start site of rat epiregulin gene by primer extension analysis and then characterized the upstream promoter region of the gene. By using a luciferase reporter system, deletion and mutation analyses of rat epiregulin gene promoter region revealed that 125 bp upstream of transcriptional start site was essential, and that two CT boxes and one GT box within this region were important for the gene expression. We also demonstrated by EMSAs that Sp1/Sp3 proteins were involved in the epiregulin gene expression via the upstream sequence. Involvement of Sp1/Sp3 was also demonstrated that transfection of Sp1 or Sp3 expression plasmids dramatically increased the epiregulin gene promoter activities about 90- or 7.9-fold, respectively, in Drosophila SL2 cells that lack endogenous Sp family proteins. Such an increase in the promoter activity was also observed in mammalian cells when NIH-3T3 cells were used. In conclusion, we demonstrated here for the first time that EGF-type growth factor epiregulin is rapidly and strongly induced in the ovarian granulosa cells by FSH stimulation, and that two CT boxes and one GT box present in the upstream region are essential for the promoter activity of rat epiregulin. We also demonstrated that Sp family members play crucial roles in the epiregulin promoter activity through the CT boxes. The restricted and hormonally regulated expression of epiregulin in the rat ovarian granulosa cells may correspond to the physiological relevance of this peptide growth factor to the FSH-induced ovarian follicular growth and maturation.
authors.affiliation: Department of Biochemistry, Fukui Medical University, Shimoaizuki, Matsuoka, Fukui 910-1193, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Sekiguchi
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Mizutani
authors.forename: Kazuya
authors.initials: K
authors.lastname: Yamada
authors.forename: Takashi
authors.initials: T
authors.lastname: Yazawa
authors.forename: Hiroko
authors.initials: H
authors.lastname: Kawata
authors.forename: Miki
authors.initials: M
authors.lastname: Yoshino
authors.forename: Takashi
authors.initials: T
authors.lastname: Kajitani
authors.forename: Takashi
authors.initials: T
authors.lastname: Kameda
authors.forename: Takashi
authors.initials: T
authors.lastname: Minegishi
authors.forename: Kaoru
authors.initials: K
authors.lastname: Miyamoto
mesh_terms: D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology; D004330:Drosophila; D004815:Epidermal Growth Factor / Q000235:genetics*; D066260:Epiregulin; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D017353:Gene Deletion; D005786:Gene Expression Regulation / Q000187:drug effects; D017930:Genes, Reporter; D006064:Gonadotropins, Equine / Q000494:pharmacology; D006107:Granulosa Cells / Q000378:metabolism; D017403:In Situ Hybridization; D008156:Luciferases / Q000235:genetics; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010053:Ovary / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D051381:Rats; D017208:Rats, Wistar; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000502:physiology; D051705:Sp3 Transcription Factor; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D004268:DNA-Binding Proteins; D066260:Epiregulin; C587882:Ereg protein, rat; D006064:Gonadotropins, Equine; D016329:Sp1 Transcription Factor; C497123:Sp3 protein, rat; D014157:Transcription Factors; D051705:Sp3 Transcription Factor; D005576:Colforsin; D004815:Epidermal Growth Factor; D005640:Follicle Stimulating Hormone; D008156:Luciferases