Two functional estrogen response elements are located upstream of the major chicken vitellogenin gene.

Abstract

We used a transient-expression assay to identify two estrogen response elements (EREs) associated with the major chicken vitellogenin gene (VTGII). Each element was characterized by its ability to confer estrogen responsiveness when cloned in either orientation next to a chimeric reporter gene consisting of the herpes simplex virus thymidine kinase promoter and the chloramphenicol acetyl transferase-coding region. Deletion analyses indicated that sequences necessary for the distal ERE resided within the region from -626 to -613 (nucleotide positions relative to the VTGII start site) whereas those necessary for the proximal ERE were within the region from -358 to -335. These distal and proximal elements contain, respectively, a perfect copy and an imperfect copy of the 13-base-pair sequence that is an essential feature of the EREs associated with two frog vitellogenin genes. These chicken VTGH EREs mapped near regions that were restructured at the chromatin level when the endogenous VTGII gene was expressed in the liver in response to estradiol. These data suggest a model for the tissue-specific expression of this estrogen-responsive gene.

Control of vitellogenin genes expression by sequences derived from transposable elements in rainbow trout

“…1). Sequence analysis between -1090 and +410 of a vtg gene did not reveal blocks of regulatory elements such as those described for the Xenopus and chicken genes [15,18]. No obvious similarity in the organization and sequence of the promoter region was observed between the rtvtg and other vertebrate vtg genes.…”

“…Because of their remarkable E2-mediated stimulation, vtg genes have for long been the model of choice to decipher the molecular mechanisms of transcriptional regulation by ERs. Most of our knowledge of the basic mechanisms of transcriptional regulation is based on Xenopus laevis and chicken vtg genes [15][16][17][18]. Besides, the tilapia vtg gene promoter [19] was shown to contain several regions exhibiting more than 70% similarity with the X. laevis vtgA2 gene promoter.…”

Toxicity of Endogenous and Environmental Estrogens: What Is the Role of Elemental Interactions?

“…Alternatively, one The paradigm noted above originally occurred to us from our studies on the EREs of hormone target genes. By way of background, the majority of experimental studies on EREs have used the so-called consensus ERE (c-ERE) originally identified in the vitellogenin genes of xenopus and chickens (9,10). This element is a 13-mer palindromic sequence, GGTCAnnnTGACC, that binds the estrogen receptor as a homodimer, confers estrogen inducibility to target genes, and is located in the 5'-flanking region of the endogenous genes (9-12).…”

Specific binding of estrogen receptor to the estrogen response element.

“…These sites of receptor interaction, called hormone response elements (HREs), are usually located upstream of the gene promoter and display enhancer properties (3,21,27,31). Regulatory estrogen response elements (EREs) have been localized by functional analyses in the 5'-flanking region of the vitellogenin genes ofXenopus laevis (21,22,27,34), the chicken vitellogenin II gene (2,21), and the rat prolactin gene (28,40). The EREs of the Xenopus vitellogenin Al and A2 genes and the chicken vitellogenin II gene are palindromic sequences with 5-base-pair (bp) stems separated by a 3-bp spacer.…”