Estrogen Receptor (ER)

What is the Estrogen Receptor (ER)?

The estrogen receptor (ER) is a nuclear receptor that binds to steroid hormone estrogen (or estradiol) and regulates gene transcription. ER can be found throughout the body but is most associated with expression in the cells of female reproductive tissue and some cancer cells. ER is a cytosolic protein, that when activated translocates into the nucleus and binds to DNA to regulate the activity of its target genes. The estrogen receptor forms a homodimer and binds to specific sites in the DNA, strategically placed next to the genes that need to be regulated. Then, the receptor activates the transcriptional machinery and starts the production of messenger RNA. The two subtypes of the estrogen receptor, ERα and ERβ, have distinct tissue distributions and functions, and differ somewhat in their transcriptional activity and response to ligands.

ER’s Role in Disease

The estrogen receptor plays a critical role in the regulation of female reproductive function. As stated above, there are two subtypes of the estrogen receptor, ERα (ESR1) and ERβ (ESR2), which are encoded by separate genes and have distinct tissue distributions and functions. ERα is primarily expressed in the uterus, mammary gland, and ovary and plays a critical role in the regulation of female reproductive function. ERα is also expressed in other tissues, such as bone and the cardiovascular system, and has been shown to have roles in metabolism, inflammation, and carcinogenesis. ERβ, on the other hand, is expressed in a wide range of tissues, including the ovary, prostate, lung, and colon, and has been shown to have diverse roles in the regulation of cell growth, differentiation, and apoptosis.

ERβ has also been implicated in the regulation of inflammation, metabolism, and neuroprotection. While both ERα and ERβ share high homology in their ligand-binding domains and DNA-binding domains, they have distinct N-terminal domains and differ in their transcriptional activity and response to ligands. ERα has been shown to be a potent transcriptional activator, while ERβ has a weaker transcriptional activity and can act as a dominant-negative regulator of ERα signaling.

ER’s Role in Drug Discovery

Drugs that target the estrogen receptors are commonly used for hormone replacement therapy (HRT) and in the treatment of breast cancer, among other conditions. Selective estrogen receptor modulators (SERMs), such as tamoxifen and raloxifene, bind to ERs and have different effects depending on the conformational shape of the liganded receptor and tissue type, thus selectively modulating the estrogenic or antiestrogenic effects of SERMs. Estrogen receptor agonists, such as estradiol and conjugated estrogens, bind to and activate ERs, and are used for HRT to alleviate menopausal symptoms. Overall, drugs that interact with ERs have important clinical applications in a range of conditions, and continued research in this area holds promise for the development of novel therapeutic strategies. Phytoestrogens are commonly found in a variety of dietary sources, such as soy, flaxseeds, and legumes, and are marketed as dietary supplements.

Due to their ability to modulate estrogenic effects, they have been suggested as potential alternatives to HRT. However, their effectiveness and safety for human consumption are still under investigation, and there is ongoing debate regarding their potential benefits and risks. While some studies suggest that phytoestrogens may have beneficial effects on bone health, cardiovascular health, and menopausal symptoms, other studies suggest potential risks, such as interference with thyroid hormone function, increased risk of breast cancer, and adverse effects on male reproductive function. As with any dietary supplement, it is important to consult with a healthcare provider before using phytoestrogen supplements.

INDIGO’s ER Reporter Assays

INDIGO Biosciences offers cell-based luciferase reporter assay kits for both Estrogen Receptor Alpha and Estrogen Receptor Beta. Our assays provide an all-inclusive luciferase reporter system that includes, in addition to ER Reporter Cells, optimized media for use during cell culture and in diluting the user’s test samples, a reference agonist, Luciferase Detection Reagent, and a cell culture-ready assay plate.

INDIGO’s cell-based reporter assays allow scientists to screen and discover drugs that can be used to treat ER-related diseases. They provide an efficient way to examine a compound for its ability to regulate nuclear receptor activity in agonist, inverse-agonist, or antagonist mode using firefly luciferase reporter gene technology. Since the receptor binding controls the expression of the luciferase reporter gene, luciferase activity in the cells can be correlated directly with the activity of the receptor. Contact us today to learn more about our Estrogen Receptor assay kits and screening capabilities!