Estradiol-mediated transcriptional activity

The test system was considerably less sensitive to endosulfan when mouse ER, rather than human ER, was used to mediate (3-gal activity (Ramamoorthy et al. 1997). In similar assays, endosulfan at 10 jM had no effect on (3-gal activity in yeast Saccharomyces) transfected with either the human or rainbow trout ER (Andersen et al. 1999). In addition, no effect was observed on transcriptional activation of HeLa cells transfected with plasmids containing an estrogen receptor as a responsive element (Shelby et al. 1996). Endosulfan also did not induce transient reporter gene expression in MCF-7 human breast cancer cells at an incubation concentration of 2.5 pM (Andersen et al. 1999). Maximum endosulfan-induced ER-mediated luciferase reporter gene expression occurred in vitro in a T47D human breast adenocarcinoma cell line at approximately 10 pM, while 50% expression of luciferase occurred at about 5.9 pM the maximum expression was approximately 59% of the effect from exposure to 0.03 nM estradiol (0.00003 pM) (Legler et al. 1999). Luciferase expression from combined treatment with endosulfan and dieldrin was additive over concentrations ranging from 3 to 8 pM. 

The mechanism of steroid receptor-mediated changes in transcription has occupied center stage over the last 40 years. Serious attention is only just beginning to be paid to the role of steroid receptors in other, often more rapid, processes that occur within minutes (15, 16), such as the estradiol-mediated activation of eNOS that proceeds in about 5 min (15). These types of responses are frequently called nongenomic to indicate that the steroid receptor does not interact with genomic... 

Estrogen (i.e. 17p-estradiol, 5) is an important hormone that mediates a wide variety of cellular responses through its binding to a specific nuclear estrogen receptor (ER).6 The hormone-bound ER forms an active dimer, which functions as a transcription factor that mediates biological response by binding to specific promoter elements of DNA to... 

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