title: Characterization of sea bass FSHβ 5' flanking region: transcriptional control by 17β-estradiol.
abstract: The sea bass follicle-stimulating hormone 5' flanking region (sbFSHβ 5' FR) was cloned and characterized in order to study the molecular mechanisms underlying transcriptional regulation of the sbFSHβ gene. Analysis of the ~3.5 kb of this region revealed the presence of several putative cis-acting elements, including steroid hormone response elements, cAMP response elements, pituitary-specific transcription factor response elements, activator protein-1 response elements and TATA sequence. Deleted constructs containing ~3.5 kb of the sbFSHβ 5' FR fused to a luciferase reporter gene were transiently transfected into human embryonic kidney (HEK 293) and mouse mature gonadotrope (LβT2) cell lines. The sbFSHβ 5' FR was efficiently expressed under basal conditions in LβT2 but not in HEK 293, pointing to both positive and negative regulatory elements. In order to elucidate the estrogen-mediated sbFSHβ transcriptional activity, in vitro treatments with 17β-estradiol were carried out on primary cultures of pituitary cells and LβT2 cells transiently expressing luciferase under the control of sbFSHβ 5' FR. Overall, these results demonstrate that 17β-estradiol inhibits sbFSHβ gene expression directly at the level of the pituitary. However, it was also shown that estrogen did not induce changes of the sbFSH promoter-directed luciferase activity, suggesting that sbFSHβ 5'FR (~3.5 kb) activity is cell type dependent and its estrogen regulation could require cis-acting elements located upstream of the promoter region, which is characterized in this article.
authors.affiliation: Department of Fish Physiology and Biotechnology, Instituto de Acuicultura de Torre de la Sal (IATS), CSIC, Torre de la Sal, 12595 Ribera de Cabanes, Castellón, Spain.
authors.forename: Borja
authors.initials: B
authors.lastname: Muriach
authors.forename: Manuel
authors.initials: M
authors.lastname: Carrillo
authors.forename: Silvia
authors.initials: S
authors.lastname: Zanuy
authors.forename: José Miguel
authors.initials: JM
authors.lastname: Cerdá-Reverter
mesh_terms: D024506:5' Flanking Region; D000818:Animals; D001483:Base Sequence; D001492:Bass / Q000235:genetics* / Q000378:metabolism; D002478:Cells, Cultured; D004958:Estradiol / Q000378:metabolism*; D029941:Fish Proteins / Q000378:metabolism*; D005640:Follicle Stimulating Hormone / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D008297:Male; D008969:Molecular Sequence Data
chemical_list: D029941:Fish Proteins; D004958:Estradiol; D005640:Follicle Stimulating Hormone