Molecular Basis of Estrogen Regulation of Hageman Factor XII Gene Expression

Estrogen therapy has been reported to cause multiple alterations hemostasis and to increase blood levels of several procoagulants, including Hageman factor [factor XII (FXII)]. Liver FXII gene ex- pression has been investigated in ovariectomized rats, treated or not with 17gestradiol. A 6-fold stimulation of FXII gene transcription was observed in treated compared to untreated animals, indicating 17P-estradiol is able to induce FXII gene expression in uiuo. We have recently shown that human FXII promoter contains an imperfect palindrome, 5'-GGGCAnnnTGACC-3', at position -43/F31 resem- bling the consensus estrogen-responsive element (ERE). Portions of different length of the FXII promoter were fused to the chloramphen- acetyltransferase (CAT) coding sequence and transiently cotrans- fected with human estrogen receptor (ER) into NIH3T3 and HepG2 cells in the presence or absence of 17P-estradiol. A 230-base pair fragment of FXII promoter, spanning nucleotides - 181/49, conferred ing that a functional ERE resides in this region. Cognate receptors, such as those for thyroid hormone or retinoic acid, did not stimulate CAT activity. Gel mobility assays demonstrated a specific interaction between ER and the 230-bp FXII promoter fragment containing the putative ERE palindrome. Similar results were obtained when an oligonucleotide spanning the consensus ERE was used; the complex between ER and FXII promoter sequences was supershifted after the addition of an anti-ER monoclonal antibody. Insertion of FXII-ERE into the heterologous thymidine kinase promoter conferred a strong estrogen responsiveness that was abolished by mutations of the 5'- half of the palindrome. These results represent the first demonstra- tion at the molecular level of the regulation of a blood coagulation factor gene by 17P-estradiol as well as the first identification of a functional ERE within this class of genes. (Endocrinology 136: 5076- 5083, 1995)