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Human ERa Reporter Assay Kit

1 x-96 well format assays
3 x-32 assays in-96 well format
1 x-384 well format assays
1 x-96 well format assays
3 x-32 assays in-96 well format
1 x-384 well format assays

Product Description and Product Data

This is an all-inclusive cell-based luciferase reporter assay kit targeting the Human Estrogen Receptor Alpha (ER). INDIGO’s ER Alpha reporter assay utilizes proprietary mammalian cells that have been engineered to provide constitutive expression of the ER Alpha. In addition to ER Alpha Reporter Cells, this kit provides two 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. The principal application of this assay is in the screening of test samples to quantify any functional activity, either agonist or antagonist, that they may exert against human ER Alpha. This kit provides researchers with clear, reproducible results, exceptional cell viability post-thaw, and consistent results lot to lot. Kits must be stored at -80C. Do not store in liquid nitrogen. Note: reporter cells cannot be refrozen or maintained in extended culture.


  • Ready to Use Upon Receipt

  • Includes All Needed Components
  • Contains Transfected Reporter Cells
  • Eliminates Cell Licensing Fees
  • Clear, Reproducible Results
  • Consistent Results Lot to Lot

Product Specifications

Target TypeNuclear Hormone Receptor
Receptor FormNative
Assay ModeAgonist, Antagonist
Kit Components
  • ERa Reporter Cells
  • Cell Recovery Medium (CRM)
  • Compound Screening Medium (CSM)
  • 17b-Estradiol, (ref. agonist; in DMSO)
  • Detection Substrate
  • Detection Buffer
  • White, sterile, cell-culture ready assay plate
Shelf Life6 months
Orthologs AvailableYes
Shipping RequirementsDry Ice
Storage temperature-80C


Human ERα Reporter cells were treated with varying concentrations of the reference agonist 17β-Estradiol (provided), PPT (4,4'4"-(4-Propyl-[1H]-pyrazole-1,3,5-triyl tris-phenol; Tocris), and (R,R)-THC ([R,R]-5,11-diethyl-5,6,11,12-tetrahydro-2,8-chrysenediol; Tocris). Concentrated stocks of agonists were prepared in DMSO; the highest concentration of DMSO in assay wells was 0.1%. Luminescence was quantified and values of average relative light units (aRLU) and corresponding standard deviation (SD) were determined for each treatment concentration (n ≥ 3). All aRLU values were percent normalized to the aRLU value of the 17β-estradiol EC100 treatment concentration. GraphPad Prism was used to curve-fit data using the least-squares method of non-linear regression and to determine EC50 values. Z’ values were calculated as described by Zhang, et al. (1999).
Human ERα antagonist assays were performed using Endoxifen, Tamoxifen citrate, ICI182780 and MPP dihydrochloride (all from Tocris). Reporter cells were co-treated with a fixed EC75 concentration of the agonist 17β-Estradiol and varying concentrations of respective challenge antagonists. INDIGO’s Live Cell Multiplex Assay (#LCM-01) was also performed to confirm that the observed drop in RLU values resulted from receptor-specific inhibition, and not from compound-induced cytotoxicity (data not shown).

Target Background

ER-alpha is encoded by the human gene ESR1 (Estrogen Receptor 1). The estrogen receptor (ESR) is a ligand-activated transcription factor composed of several domains important for hormone binding, DNA binding, and activation of transcription. Alternative splicing results in several ESR1 mRNA transcripts, which differ primarily in their 5-prime untranslated regions. The translated receptors show less variability.

INDIGO’s Estrogen Receptor Alpha Reporter Assay Systems utilize proprietary mammalian cells engineered to express constitutive, high-level expression of the full length Human Estrogen Receptor 1 (NR3A1), a ligand-dependent transcription factor commonly referred to as ERα.

INDIGO’s Estrogen Receptor Alpha Reporter Cells include the luciferase reporter gene functionally linked to an ERα-responsive promoter. Thus, quantifying changes in luciferase expression in the treated reporter cells provides a sensitive surrogate measure of the changes in ERα activity. Luciferase gene expression occurs after ligand-bound ERα undergoes nuclear translocation, DNA binding, recruitment, and assembly of the co-activators and accessory factors required to form a functional transcription complex, culminating in expression of the target gene. Unlike some other cell-based assay strategies, the readout from INDIGO’s reporter cells demands the same orchestration of all intracellular molecular interactions and events that can be expected to occur in vivo.

The principle application of this assay product is in the screening of test samples to quantify functional activities, either agonist or antagonist, that they may exert against the human estrogen receptor alpha.


Tris(1,3-dichloro-2-propyl) phosphate (TDCPP) is an organophosphate flame retardant. The primary TDCPP metabolite, bis(1,3-dichloro-2-propyl) phosphate (BDCPP), is detectable in the urine of over 90 % of Americans. Epidemiological studies show sex-specific associations between urinary BDCPP levels and metabolic syndrome, which is an established risk factor for type 2 diabetes, heart disease, and stroke. We used a mouse model to determine whether TDCPP exposure disrupts glucose homeostasis. Six-week old male and female C57BL/6J mice were given ad libitum access to diets containing vehicle (0.1 % DMSO) and TDCPP resulting in the following treatment groups: 0 mg/kg/day, 0.02 mg/kg/day, 1 mg/kg/day, or 100 mg/kg/day. After being on the experimental diet for five weeks without interruption, body composition was analyzed, glucose and insulin tolerance tests were performed, and fasting glucose and insulin levels were quantified. TDCPP at 100 mg/kg/day caused male sex-specific adiposity, fasting hyperglycemia, and insulin resistance. TDCPP-induced modulation of nuclear receptor activation was investigated using an in vitro screen to identify potential mechanisms of metabolic disruption. TDCPP activated farnesoid X receptor (FXR) and pregnane X receptor (PXR), and inhibited the androgen receptor (AR). PXR target genes, but not FXR target genes, were upregulated in livers from mice exposed to 100 mg TDCPP/kg/day. Interestingly, PXR target genes were differentially expressed in livers from both males and females. It remains to be determined whether TDCPP-induced metabolic disruption occurs via modulation of nuclear receptor activity. Taken together, these studies build upon the association of TDCPP exposure and metabolic syndrome in humans by identifying sex-specific effects of TDCPP on glucose homeostasis in mice.
Ovarian insufficiency and ovariectomy are characterized by deregulated heat loss mechanisms. Unlike hormone therapy, ERr 731 (a standardized botanical extract of Siberian rhubarb Rheum rhaponticum L. high in rhaponticin) acts like a selective estrogen receptor modulator for ERβ receptors and may offer a higher degree of safety while maintaining the desired efficacy profile. In this study, we examined the relationship between oral administration of ERr 731 and the underlying components of skin vasomotion responses in an ovariectomized (OVX) rat model. ERr 731 dose-dependently reduced tail skin temperature (Tskin) values by an average of 1 °C. The rapid onset of this effect was observed in 1 and 3 mg/kg/day ERr 731 groups as early as day 2 of administration, and remained in place for the duration of the treatment (2 weeks). Substituting ERr 731 after E2 withdrawal helped maintain body temperature similarly to E2 alone, suggesting the usefulness of ERr 731 for replacing existing hormonal therapy in humans. ERr 731 also acted as a highly selective agonist for ERβ in the hypothalamus of OVX rats, as well as in ERα/β cell-based reporter assays. These data validate the OVX/Tskin rat model as a suitable screening platform to evaluate botanical and pharmaceutical treatments of menopause, while providing further evidence for the efficacy of ERr 731 towards alleviating vasomotor menopausal symptoms and improving wellbeing during the menopausal transition.

Also available as a service

Estrogen Receptor Alpha (ERa, NR3A1)

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