Progesterone Receptor (PGR; NR3C3)

Progesterone Receptor Assay Services

The primary application of INDIGO’s cell-based nuclear receptor assays are to quantitatively assess the bioactivity of a test compound as an agonist (activator) or antagonist (inhibition of an agonist response) of a given receptor. Service assays include a positive control reference compound and ‘vehicle’ control for every experiment. A formal study report and all data files are provided to the client upon completion of the study. To receive a quote for your proposed study, complete & submit the online “Request a Quote” form or contact an INDIGO Customer Service Representative to discuss your desired study parameters.

PGR Service Assays: Human, Rat

Progesterone Receptor Background

INDIGO’s Human Progesterone Receptor (PGR) Reporter Assay System utilizes proprietary mammalian cells engineered to provide constitutive, high-level expression of human PGR (NR3C3), a ligand-dependent transcription factor.

INDIGO’s Reporter Cells include the luciferase reporter gene functionally linked to a PGR-responsive promoter. Thus, quantifying changes in luciferase expression in the treated reporter cells provides a sensitive surrogate measure of the changes in PGR activity. Luciferase gene expression occurs after ligand-bound PGR 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 in vitro binding assays, and 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.

For more information on PGR, visit the Nuclear Receptor Resource.

Synonyms: Progesterone Receptor, PGR, Human Progesterone Receptor, Human PGR, Human PR, NR3C3

Progesterone Receptor Assay Data

Agonist dose-response analyses of Human PGR. Agonist analyses of PGR Reporter Cells using Progesterone (provided), and Nomegestrol acetate (Tocris). In addition, to assess the level of background signal contributed by non-specific factors that may cause activation of the luciferase reporter gene, “mock” reporter cells were treated with Progesterone (mock reporter cells, which contain only the luciferase vector, are not provided with assay kits). Concentrated stocks prepared in DMSO were serially diluted in 5-fold decrements using CSM. Final assay concentrations for progesterone-treated cells ranged between 1,000 nM and 64 pM; assay concentrations of nomegestrol ranged between 1,000 nM and 2.4 pM. Luminescence was quantified and average relative light units (RLU) and corresponding standard deviation (SD) and Fold-Activation values were determined for each treatment concentration (n ≥ 6). Z’ values were calculated as described by Zhang, et al. (1999). Non-linear regression and EC50 analyses were performed using GraphPad Prism software. Mock reporter cells demonstrate no significant background luminescence (< 0.1% that of the reporter cells at ECMax). Thus, luminescence results strictly through ligand-activation of PGR expressed in these reporter cells. High Z' scores confirm the robust performance of this PGR Assay.

Validation of PGR Assay antagonist dose-response. Antagonist analysis of PGR Reporter Cells using Mifepristone (Tocris). Assay setup and quantification of PGR activity were performed following Protocol Variation 2 in the assay Technical Manual. To confirm that the observed dose-dependent increase in % inhibition resulted from PGR inhibition, not induced cell death, the relative numbers of live cells in each assay well were determined at the end of the treatment period using INDIGO's Live Cell Multiplex (LCM) Assay (#LCM-01). In brief: CSM was first supplemented with a 2x-EC75 concentration of progesterone. This medium was then used to prepare a 10-point, serial 4-fold dilution series of mifepristone to generate a range of 2x-concentration treatment media. Frozen PRReporter Cells were then thawed in CRM, and 100 µl of this cell suspension was dispensed into each well of the assay plate. Next, 100 µl of the prepared series of 2x-concentration treatment media were dispensed per well, combining with the reporter cells. The final assay concentration of mifepristone ranged between 10 µM and 40 pM, including a 'no antagonist' control (n ≥ 6 per treatment; highest [DMSO] < 0.1% f.c.). Each treatment also contained an assay concentration of 8.7 nM (~ EC75) progesterone as challenge agonist. Assay plates were incubated for ~23 hrs, then processed according to the LCM Assay protocol to quantify relative numbers of live cells per treatment condition. Plates were then further processed to quantify PGR activity for each treatment condition. Results: Mifepristone produced a dose-dependent increase in % inhibition of progesterone. The LCM Assay reveals no significant variance in the numbers of live cells per assay well, even up to the maximum treatment concentration of 10 µM. Hence, the measured increase in % inhibition of PGR activity can be attributed to dose-dependent inhibition of the progesterone receptor, and not to compound-induced cell death.

Progesterone Receptor Assay Services

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Research articles associated with PGR