An upstream region of the rat luteinizing hormone β gene binds estrogen receptor and confers estrogen responsiveness

摘要: Abstract Regulation of gonadotropin gene expression by sex steroids may occur via direct effects on the pituitary and/or indirect steroid hypothalamus. To study estrogen regulation rat luteinizing hormone beta (LH beta) gene, we performed receptor-DNA binding studies and transient transfer experiments. Nitrocellulose filter were with purified receptor from calf uterus labeled fragments LH gene. Dose-dependent specific to occurred only containing a common 284-base region -1388 -1105 bases upstream transcriptional start site. This DNA contained 15-base imperfect palindromic (GGACACCATCTGTCC) sequence similarity other estrogen-responsive elements. Biological function was tested inserting portions 5'-flanking next herpes simplex virus thymidine kinase promoter fused chloramphenicol acetyltransferase beta-tkCAT) performing experiments GH3 cell line. Promoter activity in beta-tkCAT constructs sequences -2013 -613, or -613 either orientation, exhibited stimulation 17 beta-estradiol (E2) treatment; contrast, -885 not regulated E2. Positive E2 dose- time-dependent stimulation, maximum 2- 6-fold effect achieved after 48 h treatment 10(-8) M The appeared be required for this biological response. Stimulation did L cells undetectable levels receptor, but cotransfection an construct vector human cDNA. These demonstrate that can bind confer hormonal responsiveness heterologous promoter. Thus, positive directly at level