title: Effects of estradiol and progesterone on gonadotropin LHβ- and FSHβ-subunit promoter activities in gonadotroph LβT2 cells.
abstract: OBJECTIVE
  Sex steroid hormones play roles in the regulation of pituitary hormone synthesis and secretion. Here we investigated the role of estradiol (E2) and progesterone (P4) on pituitary gonadotropin luteinizing hormone (LH)β- and follicle stimulating hormone (FSH)β-transcriptional activity in a single colony of gonadotroph LβT2 cells.
  
  
  METHODS
  Pituitary gonadotroph cell line, LβT2 cells were used in this study. Cells were transfected with LHβ- or FSHβ-subunit promoter region-linked luciferase vector, and stimulated with gonadotropin-releasing hormone (GnRH) in the presence or absence of sex steroids. Transcriptional activity for LHβ- and FSHβ-subunit were determined by luciferase assay. Effects of sex steroids on cell proliferation was also determined by measurement of 5-bromoe-2'-deoxyuridine (BrdU) incorporation.
  
  
  RESULTS
  The basal promoter activity of the LHβ subunit was not modulated by 10 nM E2, but gonadotropin releasing hormone (GnRH)-induced LHβ promoter activity was significantly increased by the same concentration of E2. Similarly, although the basal FSHβ promoter was not modulated by 10 nM E2, GnRH-induced FSHβ promoters were significantly potentiated in the presence of E2. One micromole E2 modulated neither basal nor GnRH-induced LHβ and FSHβ promoters. On the other hand, basal LHβ promoter activity was enhanced by 1 µM P4, but the stimulatory response of GnRH on LHβ promoters was significantly inhibited in the presence of 1 µM P4. Similar to LHβ promoters, the basal activity of the FSHβ promoter was increased by 1 µM P4; however, the response to GnRH was not modulated in the presence of P4. Ten micromoles P4 modified neither basal nor GnRH-induced promoter activity for LHβ and FSHβ. E2 had no antagonistic effect on P4-induced basal promoter activities of LHβ or FSHβ. A cell proliferation assay showed that neither E2 nor P4 modulated the growth of LβT2 cells, even in the presence or absence of GnRH.
  
  
  CONCLUSIONS
  These observations suggest that both E2 and P4 uniquely modulate basal and GnRH-stimulated gonadotropin promoters without affecting cell growth.
authors.affiliation: Department of Obstetrics and Gynecology, Shimane University School of Medicine, Izumo, Japan. kanasaki@med.shimane-u.ac.jp
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Kanasaki
authors.forename: Indri N
authors.initials: IN
authors.lastname: Purwana
authors.forename: Tselmeg
authors.initials: T
authors.lastname: Mijiddorj
authors.forename: Unurjargar
authors.initials: U
authors.lastname: Sukhbaatar
authors.forename: Aki
authors.initials: A
authors.lastname: Oride
authors.forename: Kohji
authors.initials: K
authors.lastname: Miyazaki
mesh_terms: D002461:Cell Line, Transformed; D049109:Cell Proliferation / Q000187:drug effects; D004958:Estradiol / Q000378:metabolism* / Q000494:pharmacology; D037201:Follicle Stimulating Hormone, beta Subunit / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D008156:Luciferases / Q000235:genetics; D037101:Luteinizing Hormone, beta Subunit / Q000235:genetics* / Q000378:metabolism; D010902:Pituitary Gland / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D011374:Progesterone / Q000378:metabolism* / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000502:physiology; D014162:Transfection
chemical_list: D037201:Follicle Stimulating Hormone, beta Subunit; D037101:Luteinizing Hormone, beta Subunit; D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D004958:Estradiol; D008156:Luciferases